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Sample records for acs nearby galaxy

  1. The ACS Nearby Galaxy Survey Treasury

    CERN Document Server

    Dalcanton, Julianne J; Seth, Anil C; Dolphin, Andrew; Holtzman, Jon; Rosema, Keith; Skillman, Evan D; Cole, Andrew; Girardi, Leo; Gogarten, Stephanie M; Karachentsev, Igor D; Olsen, Knut; Weisz, Daniel; Christensen, Charlotte; Freeman, Ken; Gilbert, Karoline; Gallart, Carme; Harris, Jason; Hodge, Paul; de Jong, Roelof S; Karachentseva, Valentina; Mateo, Mario; Stetson, Peter B; Tavarez, Maritza; Zaritsky, Dennis; Governato, Fabio; Quinn, Thomas

    2009-01-01

    The ACS Nearby Galaxy Survey Treasury (ANGST) is a systematic survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D14 million stars. In this paper we present the details of the sample selection, imaging, data reduction, and the resulting photometric catalogs, along with an analysis of the photometric uncertainties (systematic and random), for both t he ACS and WFPC2 imaging. We also present uniformly derived relative distances measured from the apparent magnitude of the TRGB.

  2. The ACS Nearby Galaxy Survey Treasury IV. The Star Formation History of NGC 2976

    CERN Document Server

    Williams, Benjamin F; Stilp, Adrienne; Gilbert, Karoline M; Roskar, Rok; Seth, Anil C; Weisz, Daniel; Dolphin, Andrew; Gogarten, Stephanie M; Skillman, Evan; Holtzman, Jon

    2009-01-01

    We present resolved stellar photometry of NGC 2976 obtained with the Advanced Camera for Surveys (ACS) as part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. The data cover the radial extent of the major axis of the disk out to 6 kpc, or ~6 scale lengths. The outer disk was imaged to a depth of M_F606W ~ 1, and an inner field was imaged to the crowding limit at a depth of M_F606W ~ -1. Through detailed analysis and modeling of these CMDs we have reconstructed the star formation history of the stellar populations currently residing in these portions of the galaxy, finding similar ancient populations at all radii but significantly different young populations at increasing radii. In particular, outside of the well-measured break in the disk surface brightness profile, the age of the youngest population increases with distance from the galaxy center, suggesting that star formation is shutting down from the outside-in. We use our measured star formation history, along with H I surface density measuremen...

  3. The ACS Nearby Galaxy Survey Treasury VIII. The Global Star Formation Histories of 60 Dwarf Galaxies in the Local Volume

    CERN Document Server

    Weisz, Daniel R; Williams, Benjamin F; Gilbert, Karoline M; Skillman, Evan D; Seth, Anil C; Dolphin, Andrew E; McQuinn, Kristen B W; Gogarten, Stephanie M; Holtzman, Jon; Rosema, Keith; Cole, Andrew; Karachentsev, Igor D; Zaritsky, Dennis

    2011-01-01

    We present uniformly measured star formation histories (SFHs) of 60 nearby (D~4Mpc) dwarf galaxies based on CMDs of resolved stellar populations from images taken with HST as part of the ACS Nearby Galaxy Survey Treasury program (ANGST). This volume-limited sample contains 12 dSph/dE, 5 dwarf spiral, 28 dI, 12 transition, and 3 tidal dwarf galaxies. From the best fit SFHs we find three significant results: (1) the average dwarf galaxy formed >50% of its stars by z~2 and 60% of its stars by z~1, regardless of current morphological type; (2) the mean SFHs of dIs, dTrans, and dSphs are similar over most of cosmic time, with the clearest differences appearing during the most recent 1 Gyr; and (3) the mean values are inconsistent with simple SFH models, e.g., exponentially declining SFRs. The mean SFHs are in general agreement with the cosmic SFH, although we observe offsets near z~1 that could be evidence that low mass systems experienced delayed star formation relative to more massive galaxies. The sample shows ...

  4. The ACS Nearby Galaxy Survey Treasury V. Radial Star Formation History of NGC 300

    CERN Document Server

    Gogarten, Stephanie M; Williams, Benjamin F; Roskar, Rok; Holtzman, Jon; Seth, Anil C; Dolphin, Andrew; Weisz, Daniel; Cole, Andrew; Debattista, Victor P; Gilbert, Karoline M; Olsen, Knut; Skillman, Evan; de Jong, Roelof S; Karachentsev, Igor D; Quinn, Thomas R

    2010-01-01

    We present new Hubble Space Telescope (HST) observations of NGC 300 taken as part of the ACS Nearby Galaxy Survey Treasury (ANGST). Individual stars are resolved in these images down to an absolute magnitude of M_F814W = 1.0 (below the red clump). We determine the star formation history of the galaxy in 6 radial bins by comparing our observed color-magnitude diagrams (CMDs) with synthetic CMDs based on theoretical isochrones. We find that the stellar disk out to 5.4 kpc is primarily old, in contrast with the outwardly similar galaxy M33. We determine the scale length as a function of age and find evidence for inside-out growth of the stellar disk: the scale length has increased from 1.1 +/- 0.1 kpc 10 Gyr ago to 1.3 +/- 0.1 kpc at present, indicating a buildup in the fraction of young stars at larger radii. As the scale length of M33 has recently been shown to have increased much more dramatically with time, our results demonstrate that two galaxies with similar sizes and morphologies can have very different ...

  5. THE ACS NEARBY GALAXY SURVEY TREASURY. IX. CONSTRAINING ASYMPTOTIC GIANT BRANCH EVOLUTION WITH OLD METAL-POOR GALAXIES

    International Nuclear Information System (INIS)

    In an attempt to constrain evolutionary models of the asymptotic giant branch (AGB) phase at the limit of low masses and low metallicities, we have examined the luminosity functions and number ratios between AGB and red giant branch (RGB) stars from a sample of resolved galaxies from the ACS Nearby Galaxy Survey Treasury. This database provides Hubble Space Telescope optical photometry together with maps of completeness, photometric errors, and star formation histories for dozens of galaxies within 4 Mpc. We select 12 galaxies characterized by predominantly metal-poor populations as indicated by a very steep and blue RGB, and which do not present any indication of recent star formation in their color-magnitude diagrams. Thousands of AGB stars brighter than the tip of the RGB (TRGB) are present in the sample (between 60 and 400 per galaxy), hence, the Poisson noise has little impact in our measurements of the AGB/RGB ratio. We model the photometric data with a few sets of thermally pulsing AGB (TP-AGB) evolutionary models with different prescriptions for the mass loss. This technique allows us to set stringent constraints on the TP-AGB models of low-mass, metal-poor stars (with M sun, [Fe/H]∼sun. This is also in good agreement with recent observations of white dwarf masses in the M4 old globular cluster. These constraints can be added to those already derived from Magellanic Cloud star clusters as important mileposts in the arduous process of calibrating AGB evolutionary models.

  6. The ACS Nearby Galaxy Survey Treasury I. The Star Formation History of the M81 Outer Disk

    CERN Document Server

    Williams, Benjamin F; Seth, Anil C; Weisz, Daniel; Dolphin, Andrew; Skillman, Evan; Harris, Jason; Holtzman, Jon; Girardi, Leo; de Jong, Roelof S; Olsen, Knut; Cole, Andrew; Gallart, Carme; Gogarten, Stephanie M; Hidalgo, Sebastian L; Mateo, Mario; Rosema, Keith; Stetson, Peter B; Quinn, Thomas

    2008-01-01

    The ACS Nearby Galaxy Survey Treasury (ANGST) is a large Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) treasury program to obtain resolved stellar photometry for a volume-limited sample of galaxies out to 4 Mpc. As part of this program, we have obtained deep ACS imaging of a field in the outer disk of the large spiral galaxy M81. The field contains the outskirts of a spiral arm as well as an area containing no current star formation. Our imaging results in a color-magnitude diagram (CMD) reaching to F814W = 28.8 and F606W = 29.5, one magnitude fainter than the red clump. Through detailed modeling of the full CMD, we quantify the age and metallicity distribution of the stellar populations contained in the field. The mean metallicity in the field is -1~100 Myr. We discuss the measured evolution of the M81 disk in the context of surveys of high-redshift disk galaxies and deep stellar photometry of other nearby galaxies. All of these indicate that massive spiral disks are mostly formed by z~1 and...

  7. The History of Star Formation in Galaxy Disks in the Local Volume as Measured by the ACS Nearby Galaxy Survey Treasury

    OpenAIRE

    Williams, Benjamin F; Dalcanton, Julianne J.; Johnson, L C; Weisz, Daniel R.; Seth, Anil C.; Dolphin, Andrew; Gilbert, Karoline M.; Skillman, Evan; Rosema, Keith; Gogarten, Stephanie M.; Holtzman, Jon; De Jong, Roelof S.

    2011-01-01

    We present a measurement of the age distribution of stars residing in spiral disks and dwarf galaxies. We derive a complete star formation history of the ~140 Mpc^3 covered by the volume-limited sample of galaxies in the Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury (ANGST). The total star formation rate density history is dominated by the large spirals in the volume, although the sample consists mainly of dwarf galaxies. Our measurement shows a factor of ~3 drop at z~2, in ...

  8. THE ACS NEARBY GALAXY SURVEY TREASURY. XI. THE REMARKABLY UNDISTURBED NGC 2403 DISK

    International Nuclear Information System (INIS)

    We present detailed analysis of color-magnitude diagrams of NGC 2403, obtained from a deep (m ∼–6 M☉ yr–1 kpc–2). Furthermore, we find that the cumulative stellar mass of the disk was formed at similar times at all radii. We compare these characteristics of NGC 2403 to those of its ''morphological twins'', NGC 300 and M 33, showing that the structure and age distributions of the NGC 2403 disk are more similar to those of the relatively isolated system NGC 300 than to those of the Local Group analog M 33. We also discuss the environments and HI morphologies of these three nearby galaxies, comparing them to integrated light studies of larger samples of more distant galaxy disks. Taken together, the physical properties and evolutionary history of NGC 2403 suggest that the galaxy has had no close encounters with other M 81 group members and may be falling into the group for the first time.

  9. The ACS Nearby Galaxy Survey Treasury VI. The Ancient Star Forming disk of NGC 404

    CERN Document Server

    Williams, Benjamin F; Gilbert, Karoline M; Stilp, Adrienne; Dolphin, Andrew; Seth, Anil C; Weisz, Daniel; Skillman, Evan

    2010-01-01

    We present HST/WFPC2 observations across the disk of the nearby isolated dwarf S0 galaxy NGC 404, which hosts an extended gas disk. Our deepest field reaches the red clump and main-sequence stars with ages 10 Gyr) population. Detailed modeling of the color-magnitude diagram suggests that ~70% of the stellar mass in the NGC 404 disk formed by z~2 (10 Gyr ago) and at least ~90% formed prior to z~1 (8 Gyr ago). These results indicate that the stellar populations of the NGC 404 disk are on average significantly older than those of other nearby disk galaxies, suggesting that early and late type disks may have different long-term evolutionary histories, not simply differences in their recent star formation rates. Comparisons of the spatial distribution of the young stellar mass and FUV emission in GALEX images show that the brightest FUV regions contain the youngest stars, but that some young stars (<160 Myr) lie outside of these regions. FUV luminosity appears to be strongly affected by both age and stellar mas...

  10. The ACS Nearby Galaxy Survey Treasury VII. The NGC 4214 Starburst and the Effects of Star Formation History on Dwarf Morphology

    OpenAIRE

    Williams, Benjamin F; Dalcanton, Julianne J.; Gilbert, Karoline M.; Seth, Anil C.; Weisz, Daniel R.; Evan D. Skillman; Dolphin, Andrew E.

    2011-01-01

    We present deep Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) optical observations obtained as part of the ACS Nearby Galaxy Survey Treasury (ANGST) as well as early release Wide Field Camera 3 (WFC3) ultra-violet and infrared observations of the nearby dwarf starbursting galaxy NGC 4214. Our data provide a detailed example of how covering such a broad range in wavelength provides a powerful tool for constraining the physical properties of stellar populations. The deepest data ...

  11. THE ACS NEARBY GALAXY SURVEY TREASURY. XI. THE REMARKABLY UNDISTURBED NGC 2403 DISK

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Benjamin F.; Dalcanton, Julianne J.; Stilp, Adrienne; Radburn-Smith, David [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Dolphin, Andrew [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85706 (United States); Skillman, Evan D., E-mail: ben@astro.washington.edu, E-mail: jd@astro.washington.edu, E-mail: adrienne@astro.washington.edu, E-mail: dolphin@raytheon.com, E-mail: skillman@astro.umn.edu [Department of Astronomy, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States)

    2013-03-10

    We present detailed analysis of color-magnitude diagrams of NGC 2403, obtained from a deep (m {approx}< 28) Hubble Space Telescope (HST) Wide Field Planetary Camera 2 observation of the outer disk of NGC 2403, supplemented by several shallow (m {approx}< 26) HST Advanced Camera for Surveys fields. We derive the spatially resolved star formation history of NGC 2403 out to 11 disk scale lengths. In the inner portions of the galaxy, we compare the recent star formation rates (SFRs) we derive from the resolved stars with those measured using GALEX FUV + Spitzer 24{mu} fluxes, finding excellent agreement between the methods. Our measurements also show that the radial gradient in recent SFR mirrors the disk exponential profile to 11 scale lengths with no break, extending to SFR densities a factor of {approx}100 lower than those that can be measured with GALEX and Spitzer ({approx}2 Multiplication-Sign 10{sup -6} M{sub Sun} yr{sup -1} kpc{sup -2}). Furthermore, we find that the cumulative stellar mass of the disk was formed at similar times at all radii. We compare these characteristics of NGC 2403 to those of its ''morphological twins'', NGC 300 and M 33, showing that the structure and age distributions of the NGC 2403 disk are more similar to those of the relatively isolated system NGC 300 than to those of the Local Group analog M 33. We also discuss the environments and HI morphologies of these three nearby galaxies, comparing them to integrated light studies of larger samples of more distant galaxy disks. Taken together, the physical properties and evolutionary history of NGC 2403 suggest that the galaxy has had no close encounters with other M 81 group members and may be falling into the group for the first time.

  12. The History of Star Formation in Galaxy Disks in the Local Volume as Measured by the ACS Nearby Galaxy Survey Treasury

    CERN Document Server

    Williams, Benjamin F; Johnson, L C; Weisz, Daniel R; Seth, Anil C; Dolphin, Andrew; Gilbert, Karoline M; Skillman, Evan; Rosema, Keith; Gogarten, Stephanie M; Holtzman, Jon; de Jong, Roelof S

    2011-01-01

    We present a measurement of the age distribution of stars residing in spiral disks and dwarf galaxies. We derive a complete star formation history of the ~140 Mpc^3 covered by the volume-limited sample of galaxies in the Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury (ANGST). The total star formation rate density history is dominated by the large spirals in the volume, although the sample consists mainly of dwarf galaxies. Our measurement shows a factor of ~3 drop at z~2, in approximate agreement with results from other measurement techniques. While our results show that the overall star formation rate density has decreased since z~1, the measured rates during this epoch are higher than those obtained from other measurement techniques. This enhanced recent star formation rate appears to be largely due to an increase in the fraction of star formation contained in low-mass disks at recent times. Finally, our results indicate that despite the differences at recent times, the epoch of formation o...

  13. The ACS Nearby Galaxy Survey Treasury XI. The Remarkably Undisturbed NGC 2403 Disk

    CERN Document Server

    Williams, Benjamin F; Stilp, Adrienne; Dolphin, Andrew; Skillman, Evan D; Radburn-Smith, David

    2013-01-01

    We present detailed analysis of color-magnitude diagrams of NGC2403, obtained from a deep (m<28) Hubble Space Telescope (HST) Wide Field Planetary Camera 2 observation of the outer disk of NGC2403, supplemented by several shallow (m<26) HST Advanced Camera for Surveys fields. We derive the spatially resolved star formation history of NGC2403 out to 11 disk scale lengths. In the inner portions of the galaxy, we compare the recent star formation rates (SFRs) we derive from the resolved stars with those measured using GALEX FUV + Spitzer 24-micron fluxes, finding excellent agreement between the methods. Our measurements also show that the radial gradient in recent SFR mirror s the disk exponential profile to 11 scale lengths with no break, extending to SFR densities a factor of 100 lower than those that can be measured with GALEX and Spitzer (2x10^{-6} M_{\\sun} yr^{-1} kpc^{-2}). Furthermore, we find that the cumulative stellar mass of the disk was formed at similar times at all radii. We compare these cha...

  14. Nuclear activity in nearby galaxies

    NARCIS (Netherlands)

    Filho, Mercedes Esteves

    2003-01-01

    The main focus of this thesis has been the search for and study of low luminosity AGN. We have detected severa low luminosity AGN in nearby galaxies, revealing that this type of activity can occur in a broad range of galaxy types and powers. Furthermore, we have been able to establish importan const

  15. Satellite galaxies in nearby groups of galaxies

    CERN Document Server

    Vennik, J

    2015-01-01

    We analyse distribution, kinematics and star-formation (SF) properties of satellite galaxies in three different samples of nearby groups. We find that studied groups are generally well approximated by low-concentration NFW model, show a variety of LOS velocity dispersion profiles and signs of SF quenching in outskirts of dwarf satellite galaxies.

  16. The ACS Nearby Galaxy Survey Treasury VII. The NGC 4214 Starburst and the Effects of Star Formation History on Dwarf Morphology

    CERN Document Server

    Williams, Benjamin F; Gilbert, Karoline M; Seth, Anil C; Weisz, Daniel R; Skillman, Evan D; Dolphin, Andrew E

    2011-01-01

    We present deep Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) optical observations obtained as part of the ACS Nearby Galaxy Survey Treasury (ANGST) as well as early release Wide Field Camera 3 (WFC3) ultra-violet and infrared observations of the nearby dwarf starbursting galaxy NGC 4214. Our data provide a detailed example of how covering such a broad range in wavelength provides a powerful tool for constraining the physical properties of stellar populations. The deepest data reach the ancient red clump at M_F814W -0.2. All of the optical data reach the main sequence turnoff for stars younger than ~300 Myr, and the blue He burning sequence for stars younger than 500 Myr. The full CMD-fitting analysis shows that all three fields in our data set are consistent with ~75% of the stellar mass being older than 8 Gyr, in spite of showing a wide range in star formation rates at the present day. Thus, our results suggest that the scale length of NGC 4214 has remained relatively constant for many Gyr. A...

  17. Nuclear Activity in Nearby Galaxies

    Directory of Open Access Journals (Sweden)

    Thaisa Bergmann Storchi

    2001-01-01

    Full Text Available I discuss some recent observational results in the research of nearby active galactic nuclei (AGN. These results cover three main topics: (i evidences for the current paradigm for AGN´s, which includes a nuclear supermassive blackhole (SMBH fed via an accretion disk; (ii evidence that this paradigm may also apply to LINER´s, the lowest luminous AGN´s and to normal galaxies; (iii evidences of how the fueling of the SMBH occurs and its relation to recent and intermediate age (106 to 108 yrs old episodes of star formation.

  18. The AGN Population in Nearby Galaxies

    NARCIS (Netherlands)

    Filho, Mercedes; Barthel, Peter; Ho, Luis

    2006-01-01

    In order to determine the incidence of black hole accretion-driven nuclear activity in nearby galaxies, we have compiled radio data for the LINERs, composite LINER,/Hn and Seyfert galaxies from a complete magnitude-limited sample of bright nearby galaxies (Palomar sample). Our results show an overal

  19. Surface photometry of new nearby dwarf galaxies

    CERN Document Server

    Makarova, L N; Grebel, E K; Barsunova, O Y

    2002-01-01

    We present CCD surface photometry of 16 nearby dwarf galaxies, many of which were only recently discovered. Our sample comprises both isolated galaxies and galaxies that are members of nearby galaxy groups. The observations were obtained in the Johnson B and V bands (and in some cases in Kron-Cousins I). We derive surface brightness profiles, total magnitudes, and integrated colors. For the 11 galaxies in our sample with distance estimates the absolute B magnitudes lie in the range of -10>Mb>-13. The central surface brightness ranges from 22.5 to 27.0 mag/sq.arcsec. Most of the dwarf galaxies show exponential light profiles with or without a central light depression. Integrated radial color gradients, where present, appear to indicate a more centrally concentrated younger population and a more extended older population.

  20. HUBBLE SPACE TELESCOPE ACS IMAGING OF THE GOALS SAMPLE: QUANTITATIVE STRUCTURAL PROPERTIES OF NEARBY LUMINOUS INFRARED GALAXIES WITH LIR > 1011.4 L☉

    International Nuclear Information System (INIS)

    A Hubble Space Telescope/Advanced Camera for Surveys study of the structural properties of 85 luminous and ultraluminous (LIR > 1011.4 L☉) infrared galaxies (LIRGs and ULIRGs) in the Great Observatories All-sky LIRG Survey (GOALS) sample is presented. Two-dimensional GALFIT analysis has been performed on F814W ''I-band'' images to decompose each galaxy, as appropriate, into bulge, disk, central point-spread function (PSF) and stellar bar components. The fraction of bulge-less disk systems is observed to be higher in LIRGs (35%) than in ULIRGs (20%), with the disk+bulge systems making up the dominant fraction of both LIRGs (55%) and ULIRGs (45%). Further, bulge+disk systems are the dominant late-stage merger galaxy type and are the dominant type for LIRGs and ULIRGs at almost every stage of galaxy-galaxy nuclear separation. The mean I-band host absolute magnitude of the GOALS galaxies is –22.64 ± 0.62 mag (1.8+1.4-0.4 L*I), and the mean bulge absolute magnitude in GOALS galaxies is about 1.1 mag fainter than the mean host magnitude. Almost all ULIRGs have bulge magnitudes at the high end (–20.6 to –23.5 mag) of the GOALS bulge magnitude range. Mass ratios in the GOALS binary systems are consistent with most of the galaxies being the result of major mergers, and an examination of the residual-to-host intensity ratios in GOALS binary systems suggests that smaller companions suffer more tidal distortion than the larger companions. We find approximately twice as many bars in GOALS disk+bulge systems (32.8%) than in pure-disk mergers (15.9%) but most of the disk+bulge systems that contain bars are disk-dominated with small bulges. The bar-to-host intensity ratio, bar half-light radius, and bar ellipticity in GOALS galaxies are similar to those found in nearby spiral galaxies. The fraction of stellar bars decreases toward later merger stages and smaller nuclear separations, indicating that bars are destroyed as the merger advances. In contrast, the fraction of

  1. HST/ACS Observations of Star Formation Driven Outflows in Nearby Edge-on Spiral Galaxies: Dependence of Halo Morphology on Star Formation Activity

    OpenAIRE

    Rossa, Joern; Dahlem, Michael; Dettmar, Ralf-Juergen; van der Marel, Roeland P.

    2008-01-01

    (Abridged). We present new high spatial resolution narrowband imaging observations of extraplanar diffuse ionized gas (eDIG) in four late-type, actively star forming edge-on spirals, obtained with ACS on-board HST. Our F658N (H-alpha) observations reveal a multitude of structures on both small and large scales. Whereas all four galaxies have been studied with ground-based telescopes before, here the small scale structure of the extended emission line gas is presented for the first time at a s...

  2. HST/ACS Observations of Star Formation Driven Outflows in Nearby Edge-on Spiral Galaxies: Dependence of Halo Morphology on Star Formation Activity

    CERN Document Server

    Rossa, Joern; Dettmar, Ralf-Juergen; van der Marel, Roeland P

    2008-01-01

    (Abridged). We present new high spatial resolution narrowband imaging observations of extraplanar diffuse ionized gas (eDIG) in four late-type, actively star forming edge-on spirals, obtained with ACS on-board HST. Our F658N (H-alpha) observations reveal a multitude of structures on both small and large scales. Whereas all four galaxies have been studied with ground-based telescopes before, here the small scale structure of the extended emission line gas is presented for the first time at a spatial resolution of 0.05", corresponding to 5.0 pc at the mean distance to the target galaxies. The eDIG morphology is very different for all four targets, probably as a result of their different levels of star formation activity. We find that the morphology of the eDIG, in particular the break-up of diffuse emission into filaments in galaxy halos, shows a strong dependence on the level of star formation activity per unit area, and eDIG can be arranged into a morphological sequence. NGC4634 and NGC5775 have the highest S...

  3. Infrared Galaxies in the Nearby Universe

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We used the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) to study the morphological properties of 1137 nearby infrared (IR) galaxies, most of which are brighter than 15.9 mag in r-band. This sample was drawn from a cross-correlation of the Infra-Red Astronomical Satellite (IRAS) point source catalog redshift survey with DR5 at z(≤)0.08. Based on this IR galaxy sample, we constructed five volume-limited sub-samples with IR luminosity ranging from 109.5L⊙ to 1012L⊙. By deriving the IR luminosity functions (LF) for different morphological types, we found that normal spiral galaxies are the dominant population below LIR~ 8 × 1010 L⊙; while the fraction of barred spiral galaxies increases with increasing IR luminosity and becomes dominant in spiral galaxies beyond LIR(≈) 5×1010L⊙. As the IR luminosity decreases, the IR galaxies become more compact and have lower stellar masses. The analysis also shows that normal spiral galaxies give the dominant contribution to the total comoving IR energy density in the nearby universe, while, in contrast, the contribution from peculiar galaxies is only 39%.

  4. Orbital masses of nearby luminous galaxies

    International Nuclear Information System (INIS)

    We use observational properties of galaxies accumulated in the Updated Nearby Galaxy Catalog to derive a dark matter mass of luminous galaxies via motions of their companions. The data on orbital-to-stellar mass ratio are presented for 15 luminous galaxies situated within 11 Mpc from us: the Milky Way, M31, M81, NGC 5128, IC342, NGC 253, NGC 4736, NGC 5236, NGC 6946, M101, NGC 4258, NGC 4594, NGC 3115, NGC 3627, and NGC 3368, as well as for a composite suite around other nearby galaxies of moderate and low luminosity. The typical ratio for these galaxies is M orb/M * = 31, corresponding to the mean local density of matter Ω m = 0.09, i.e., one-third of the global cosmic density. This quantity seems to be rather an upper limit of dark matter density, since the peripheric population of the suites may suffer from the presence of fictitious unbound members. We note that the Milky Way and M31 halos have lower dimensions and lower stellar masses than those of the other 13 nearby luminous galaxies. However, the dark-to-stellar mass ratio for both the Milky Way and M31 is typical for other neighboring luminous galaxies. The distortion in the Hubble flow, observed around the Local Group and five other neighboring groups, yields their total masses within the radius of a zero velocity surface, R 0; these masses are slightly lower than the orbital and virial values. This difference may be due to the effect of dark energy producing a kind of 'mass defect' within R 0.

  5. Suites of dwarfs around Nearby giant galaxies

    International Nuclear Information System (INIS)

    The Updated Nearby Galaxy Catalog (UNGC) contains the most comprehensive summary of distances, radial velocities, and luminosities for 800 galaxies located within 11 Mpc from us. The high density of observables in the UNGC makes this sample indispensable for checking results of N-body simulations of cosmic structures on a ∼1 Mpc scale. The environment of each galaxy in the UNGC was characterized by a tidal index Θ1, depending on the separation and mass of the galaxy's main disturber (MD). We grouped UNGC galaxies with a common MD in suites, and ranked suite members according to their Θ1. All suite members with positive Θ1 are assumed to be physical companions of the MD. About 58% of the sample are members of physical groups. The distribution of suites by the number of members, n, follows a relation N(n) ∼ n –2. The 20 most populated suites contain 468 galaxies, i.e., 59% of the UNGC sample. The fraction of MDs among the brightest galaxies is almost 100% and drops to 50% at MB = –18m. We discuss various properties of MDs, as well as galaxies belonging to their suites. The suite abundance practically does not depend on the morphological type, linear diameter, or hydrogen mass of the MD, the tightest correlation being with the MD dynamical mass. Dwarf galaxies around MDs exhibit well-known segregation effects: the population of the outskirts has later morphological types, richer H I contents, and higher rates of star formation activity. Nevertheless, there are some intriguing cases where dwarf spheroidal galaxies occur at the far periphery of the suites, as well as some late-type dwarfs residing close to MDs. Comparing simulation results with galaxy groups, most studies assume the Local Group is fairly typical. However, we recognize that the nearby groups significantly differ from each other and there is considerable variation in their properties. The suites of companions around the Milky Way and M31, consisting of the Local Group, do not quite seem to

  6. Molecular gas in nearby powerful radio galaxies

    CERN Document Server

    Leon, S; Combes, F; Van Trung, D

    2001-01-01

    We report the detection of CO(1-0) and CO(2-1) emission from the central region of nearby 3CR radio galaxies (z$<$ 0.03). Out of 21 galaxies, 8 have been detected in, at least, one of the two CO transitions. The total molecular gas content is below 10$^9$ \\msun. Their individual CO emission exhibit, for 5 cases, a double-horned line profile that is characteristic of an inclined rotating disk with a central depression at the rising part of its rotation curve. The inferred disk or ring distributions of the molecular gas is consistent with the observed presence of dust disks or rings detected optically in the cores of the galaxies. We reason that if their gas originates from the mergers of two gas-rich disk galaxies, as has been invoked to explain the molecular gas in other radio galaxies, then these galaxies must have merged a long time ago (few Gyr or more) but their remnant elliptical galaxies only recently (last 10$^7$ years or less) become active radio galaxies. Instead, we argue the the cannibalism of g...

  7. Symposium “Mapping the Galaxy and Nearby Galaxies”

    CERN Document Server

    Wada, Keiichi; ASTROPHYSICS AND SPACE SCIENCE PROCEEDINGS

    2008-01-01

    This is a proceedings book of the symposium "Mapping the Galaxy and Nearby Galaxies" held on Ishigaki Island, Okinawa, Japan, on June 25 – 30, 2006. The symposium focused on mapping the interstellar media and other components in galaxies. Latest results of the following main topics are presented in the volume: Our Galaxy -- mass distribution, local ISM, supermassive black holes and their environments Central part of nearby galaxies -- ISM around starbursts, fueling mechanisms Nearby Galaxies -- molecular gas and star formation, gas dynamics Galactic environment and evolution -- formation of our Galaxy, origin of supermassive black holes The nature of the Dark Matter component -- effects on the internal structures of galaxies

  8. WINGS: WFIRST Infrared Nearby Galaxy Survey

    Science.gov (United States)

    Williams, Benjamin

    WFIRST's combination of wide field and high resolution will revolutionize the study of nearby galaxies. We propose to produce and analyze simulated WFIRST data of nearby galaxies and their halos to maximize the scientific yield in the limited observing time available, ensuring the legacy value of WFIRST's eventual archive. We will model both halo structure and resolved stellar populations to optimize WFIRST's constraints on both dark matter and galaxy formation models in the local universe. WFIRST can map galaxy structure down to ~35 mag/square arcsecond using individual stars. The resulting maps of stellar halos and accreting dwarf companions will provide stringent tests of galaxy formation and dark matter models on galactic (and even sub-galactic) scales, which is where the most theoretical tension exists with the Lambda-CDM model. With a careful, coordinated plan, WFIRST can be expected to improve current sample sizes by 2 orders of magnitude, down to surface brightness limits comparable to those currently reached only in the Local Group, and that are >4 magnitudes fainter than achievable from the ground due to limitations in star-galaxy separation. WFIRST's maps of galaxy halos will simultaneously produce photometry for billions of stars in the main bodies of galaxies within 10 Mpc. These data will transform studies of star formation histories that track stellar mass growth as a function of time and position within a galaxy. They also will constrain critical stellar evolution models of the near-infrared bright, rapidly evolving stars that can contribute significantly to the integrated light of galaxies in the near-infrared. Thus, with WFIRST we can derive the detailed evolution of individual galaxies, reconstruct the complete history of star formation in the nearby universe, and put crucial constraints on the theoretical models used to interpret near-infrared extragalactic observations. We propose a three-component work plan that will ensure these gains by

  9. Hα Imaging of Nearby Seyfert Host Galaxies

    Science.gov (United States)

    Theios, Rachel L.; Malkan, Matthew A.; Ross, Nathaniel R.

    2016-05-01

    We used narrowband (Δλ = 70 Å) interference filters with the CCD imaging camera on the Nickel 1.0 m telescope at Lick Observatory to observe 31 nearby (z extinction. We separated the Hα emission line of the “nucleus” (central 100-1000 pc) from that of the host galaxy. The extended Hα emission is expected to be powered by newly formed hot stars, and indeed correlates well with other indicators of current star formation rates (SFRs) in these galaxies: extended 7.7 μm polycyclic aromatic hydrocarbon, total far-infrared, and radio luminosity. Relative to what would be expected from recent star formation, there is a 0.8 dex excess of radio emission in our Seyfert galaxies. The Hα luminosity we measured in the centers of our galaxies is dominated by the active galactic nucleus (AGN), and is linearly correlated with the hard X-ray luminosity. There is, however, an upward offset of 1 dex in this correlation for the Seyfert 1s, because their nuclear Hα emission includes a strong additional contribution from the broad-line region. We found a correlation between SFR and AGN luminosity. In spite of selection effects, we concluded that the absence of bright Seyfert nuclei in galaxies with low SFRs is real, albeit only weakly significant. Finally, we used our measured spatial distributions of Hα emission to determine what these Seyfert galaxies would look like when observed through fixed apertures (e.g., a spectroscopic fiber) at high redshifts. We found that although all of these Seyfert galaxies would be detectable emission-line galaxies at any redshift, most of them would appear to be dominated by (>67%) their H ii region emission. Only the most luminous AGNs (log(L Hα /erg s-1) > 41.5) would still be identified as such at z ˜ 0.3.

  10. The NICMOS Snapshot Survey of nearby Galaxies

    CERN Document Server

    Böker, T; Sparks, W

    1999-01-01

    We present ``snapshot'' observations with the NearInfrared Camera and MultiObject Spectrometer (NICMOS) on board the Hubble Space Telescope (HST) of 94 nearby galaxies from the Revised Shapley Ames Catalog. Images with 0.2 as resolution were obtained in two filters, a broad-band continuum filter (F160W, roughly equivalent to the H-band) and a narrow band filter centered on the Paschen alpha line (F187N or F190N, depending on the galaxy redshift) with the 51x51 as field of view of the NICMOS camera 3. A first-order continuum subtraction is performed, and the resulting line maps and integrated Paschen alpha line fluxes are presented. A statistical analysis indicates that the average Paschen alpha surface brightness {\\bf in the central regions} is highest in early-type (Sa-Sb) spirals.

  11. LABOCA observations of nearby, active galaxies

    CERN Document Server

    Weiss, A; Guesten, R; Menten, K M; Schuller, F; Siringo, G; Kreysa, E

    2008-01-01

    We present large scale 870 micron maps of the nearby starburst galaxies NGC253, NGC4945 and the nearest giant elliptical radio galaxy Centaurus A (NGC 5128) obtained with the newly commissioned Large Apex Bolometer Camera (LABOCA) operated at the APEX telescope. Our continuum images reveal for the first time the distribution of cold dust at a angular resolution of 20" across the entire optical disks of NGC253 and NGC4945 out to a radial distance of 10' (7.5 kpc). In NGC5128 our LABOCA image also shows, for the first time at submillimeter wavelengths, the synchrotron emission associated with the radio jet and the inner radio lobes. From an analysis of the 870 micron emission in conjunction with ISO-LWS, IRAS and long wavelengths radio data we find temperatures for the cold dust in the disks of all three galaxies of 17-20 K, comparable to the dust temperatures in the disk of the Milky Way. The total gas mass in the three galaxies is determined to be 2.1, 4.2 and 2.8 x 10^9 solar masses for NGC253, NGC4945 and N...

  12. MaNGA: Mapping Nearby Galaxies at Apache Point Observatory

    CERN Document Server

    Weijmans, Anne-Marie

    2015-01-01

    MaNGA (Mapping Nearby Galaxies at APO) is a galaxy integral-field spectroscopic survey within the fourth generation Sloan Digital Sky Survey (SDSS-IV). It will be mapping the composition and kinematics of gas and stars in 10,000 nearby galaxies, using 17 differently sized fiber bundles. MaNGA's goal is to provide new insights in galaxy formation and evolution, and to deliver a local benchmark for current and future high-redshift studies.

  13. MaNGA: Mapping Nearby Galaxies at Apache Point Observatory

    Science.gov (United States)

    Weijmans, A.-M.; MaNGA Team

    2016-10-01

    MaNGA (Mapping Nearby Galaxies at APO) is a galaxy integral-field spectroscopic survey within the fourth generation Sloan Digital Sky Survey (SDSS-IV). It will be mapping the composition and kinematics of gas and stars in 10,000 nearby galaxies, using 17 differently sized fiber bundles. MaNGA's goal is to provide new insights in galaxy formation and evolution, and to deliver a local benchmark for current and future high-redshift studies.

  14. Gravitational Lensing by Nearby Clusters of Galaxies

    CERN Document Server

    Cypriano, E S; Campusano, L E; Kneib, J P; Giovanelli, R; Haynes, M P; Dale, D A; Hardy, E; Cypriano, Eduardo S.; Sodré, Laerte; Campusano, Luis E.; Kneib, Jean-Paul; Giovanelli, Riccardo; Haynes, Martha P.; Dale, Daniel A.; Hardy, Eduardo

    2001-01-01

    We present an estimation of the expected number of arcs and arclets in a sample of nearby (z<0.1) clusters of galaxies, that takes into account the magnitude limit of the objects as well as seeing effects. We show that strong lensing effects are not common, but also they are not as rare as usually stated. Indeed, for a given cluster, they present a strong dependence with the magnitude limit adopted in the analysis and the seeing of the observations. We also describe the procedures and results of a search for lensing effects in a sample of 33 clusters spanning the redshift range of 0.014 to 0.076, representative of the local cluster distribution. This search produced two arc candidates. The first one is in A3408 (z=0.042), the same arc previously discovered by Campusano & Hardy (1996), with z=0.073 and associated to the brightest cluster galaxy. The second candidate is in the cluster A3266 (z=0.059) and is near a bright elliptical outside the cluster center, requiring the presence of a very massive sub-...

  15. Molecular Gas & Star Formation in Nearby Galaxies

    CERN Document Server

    Wong, T; Thornley, Michele D.; Wong, Tony

    2004-01-01

    We review recent observations of molecular gas in nearby galaxies and their implications for the star formation law on large (>1 kpc) scales. High-resolution data provided by millimetre interferometers are now adding to the basic understanding that has been provided by single-dish telescopes. In particular, they confirm the good correlation between star formation rate (SFR) and molecular gas surface densities, while at the same time revealing a greater degree of heterogeneity in the CO distribution. Galaxies classified as SAB or SB tend to show radial CO profiles that peak sharply in the inner ~20 arcsec, indicative of bar-driven inflow. The observed Schmidt law index of ~1.5 may result from a nearly linear relation between SFR and H_2 mass coupled with a modest dependence of the molecular gas fraction on the total gas density. The normalisation of the Schmidt law, giving the characteristic timescale for star formation, may stem from the generic nature of interstellar turbulence.

  16. HUBBLE SURVEYS DYING STARS IN NEARBY GALAXY

    Science.gov (United States)

    2002-01-01

    From ground-based telescopes, the glowing gaseous debris surrounding dying, sun-like stars in a nearby galaxy, called the Large Magellanic Cloud, appear as small, shapeless dots of light. But through the 'eyes' of NASA's Hubble Space Telescope, these bright dots take on a variety of shapes, from round- to pinwheel-shaped clouds of gas. Using Hubble's Space Telescope Imaging Spectrograph, scientists probed the glowing gas surrounding 27 dying stars, called planetary nebulae, in the Large Magellanic Cloud. The observations represent the most detailed study of planetary nebulae outside the Milky Way. The six objects in the picture illustrate the assortment of planetary nebulae identified in the galaxy. SMP 16, 30, and 93 are examples of a bipolar nebula, twin lobes of gas projecting away from a dying star. SMP 10 has a pinwheel shape and is known as a 'point-symmetric' nebula. SMP 4 has an elliptical appearance, and SMP 27, consisting of four lobes of gas, is called a 'quadrupolar' nebula. The lines point to the objects' locations in the Large Magellanic Cloud. A ground-based observatory snapped the picture of this galaxy. In the pictures of the planetary nebulae, color corresponds to temperature. Blue represents hotter regions of the nebulae and red, cooler. Scientists are probing these illuminated stellar relics in our neighboring galaxy because they are at relatively the same distance - about 168,000 light-years -- from Earth. Knowing the distance to these objects allows scientists to compare their shapes and sizes, and precisely determine the brightness of their central stars. For this reason, even though these glowing remains of dying stars are about 50 times farther away than the stunning planetary nebulae photographed in the Milky Way, they are of invaluable importance. By sampling this population, scientists noticed that the bipolar nebulae are richer in some heavier elements, such as neon, than those with a more spherical shape. At the dawn of the universe

  17. HUBBLE SURVEYS DYING STARS IN NEARBY GALAXY

    Science.gov (United States)

    2002-01-01

    From ground-based telescopes, the glowing gaseous debris surrounding dying, sun-like stars in a nearby galaxy, called the Large Magellanic Cloud, appear as small, shapeless dots of light. But through the 'eyes' of NASA's Hubble Space Telescope, these bright dots take on a variety of shapes, from round- to pinwheel-shaped clouds of gas. Using Hubble's Space Telescope Imaging Spectrograph, scientists probed the glowing gas surrounding 27 dying stars, called planetary nebulae, in the Large Magellanic Cloud. The observations represent the most detailed study of planetary nebulae outside the Milky Way. The six objects in the picture illustrate the assortment of planetary nebulae identified in the galaxy. SMP 16, 30, and 93 are examples of a bipolar nebula, twin lobes of gas projecting away from a dying star. SMP 10 has a pinwheel shape and is known as a 'point-symmetric' nebula. SMP 4 has an elliptical appearance, and SMP 27, consisting of four lobes of gas, is called a 'quadrupolar' nebula. The lines point to the objects' locations in the Large Magellanic Cloud. A ground-based observatory snapped the picture of this galaxy. In the pictures of the planetary nebulae, color corresponds to temperature. Blue represents hotter regions of the nebulae and red, cooler. Scientists are probing these illuminated stellar relics in our neighboring galaxy because they are at relatively the same distance - about 168,000 light-years -- from Earth. Knowing the distance to these objects allows scientists to compare their shapes and sizes, and precisely determine the brightness of their central stars. For this reason, even though these glowing remains of dying stars are about 50 times farther away than the stunning planetary nebulae photographed in the Milky Way, they are of invaluable importance. By sampling this population, scientists noticed that the bipolar nebulae are richer in some heavier elements, such as neon, than those with a more spherical shape. At the dawn of the universe

  18. FIR colours and SEDs of nearby galaxies observed with Herschel

    OpenAIRE

    Boselli, A.; Ciesla, L.; Buat, V.; Cortese, L.; Auld, R.; Baes, Maarten; Bendo, GJ; S. Bianchi; Bock, J.; Bomans, DJ; Bradford, M; Castro-Rodriguez, N.; Chanial, P.; Charlot, S.; Clemens, M.

    2010-01-01

    We present infrared colours (in the 25-500 mu m spectral range) and UV to radio continuum spectral energy distributions of a sample of 51 nearby galaxies observed with SPIRE on Herschel. The observed sample includes all morphological classes, from quiescent ellipticals to active starbursts. Active galaxies have warmer colour temperatures than normal spirals. In ellipticals hosting a radio galaxy, the far-infrared (FIR) emission is dominated by the synchrotron nuclear emission. The colour temp...

  19. A Survey of nearby, nearly face-on spiral galaxies

    Science.gov (United States)

    Garmire, Gordon

    2014-09-01

    This is a continuation of a survey of nearby, nearly face-on spiral galaxies. The main purpose is to search for evidence of collisions with small galaxies that show up in X-rays by the generation of hot shocked gas from the collision. Secondary objectives include study of the spatial distribution point sources in the galaxy and to detect evidence for a central massive blackhole.

  20. FIR colours and SEDs of nearby galaxies observed with Herschel

    OpenAIRE

    Boselli, A.; Bock, J.; Bradford, M; Fadda, D.; Levenson, L.; Lu, N.; Schulz, B.; Wright, G.

    2010-01-01

    We present infrared colours (in the 25−500 μm spectral range) and UV to radio continuum spectral energy distributions of a sample of 51 nearby galaxies observed with SPIRE on Herschel. The observed sample includes all morphological classes, from quiescent ellipticals to active starbursts. Active galaxies have warmer colour temperatures than normal spirals. In ellipticals hosting a radio galaxy, the far-infrared (FIR) emission is dominated by the synchrotron nuclear emission. The colour temper...

  1. Star Formation in Nearby Isolated Galaxies

    CERN Document Server

    Karachentsev, I D; Melnyk, O V; Courtois, H M

    2013-01-01

    We use the FUV fluxes measured with the GALEX to study the star formation properties of galaxies collected in the "Local Orphan Galaxies" catalog (LOG). Among 517 LOG galaxies having radial velocities V(LG) 15 degr, 428 objects have been detected in FUV. We briefly discuss some scaling relations between the specific star formation rate (SSFR) and stellar mass, HI-mass, morphology, and surface brightness of galaxies situated in extremely low density regions of the Local Supercluster. Our sample is populated with predominantly late-type, gas-rich objects with the median morphological type of Sdm. Only 5% of LOG galaxies are classified as early types: E, S0, S0/a, however, they systematically differ from normal E and S0 galaxies by lower luminosity and presence of gas and dust. We find that almost all galaxies in our sample have their SSFR below 0.4 [Gyr^{-1}]. This limit is also true even for a sample of 270 active star-burst Markarian galaxies situated in the same volume. The existence of such a quasi-Eddingt...

  2. The Evolution of Nearby Dwarf Galaxies

    NARCIS (Netherlands)

    Tolstoy, E.; Koleva, M; Prugniel, P; Vauglin,

    2011-01-01

    Within the Local Universe galaxies can be studied in great detail star by star. The Colour-Magnitude Diagram synthesis analysis method is well established as the most accurate way to determine the detailed star formation history of galaxies going back to the earliest times. This approach has benefit

  3. Molecular gas in nearby powerful radio galaxies

    CERN Document Server

    Ocana-Flaquer, B; Lim, L; Dinh-V-Trung,; Combes, F

    2009-01-01

    Powerful radio-AGN are normally hosted by massive elliptical galaxies which are usually very poor in molecular gas. Nevertheless the gas is needed in the very center to feed the nuclear activity. Thus it is important to study the origin, the distribution and the kinematics of the molecular gas in such objects. We have performed at the IRAM-30m telescope a survey of the CO(1-0) and CO(2-1) emission in the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio-continuum fluxes. The main result of this survey is the very low content in molecular gas of such galaxies compared to FIR selected galaxies. The median value of the molecular gas mass, taking into account the upper limits, is 1x10^8 Msun; if we calculate it for all the galaxies together, and if we separate them into FR-I and FR-II type galaxies, an important difference is found between them. Moreover, the CO spectra indicates the presence of a central molecular gas disk in these radio galaxies. Our results contrast ...

  4. Extended HI disks in nearby spiral galaxies

    CERN Document Server

    Bosma, A

    2016-01-01

    In this short write-up, I will concentrate on a few topics of interest. In the 1970s I found very extended HI disks in galaxies such as NGC 5055 and NGC 2841, out to 2 - 2.5 times the Holmberg radius. Since these galaxies are warped, a "tilted ring model" allows rotation curves to be derived, and evidence for dark matter to be found. The evaluation of the amount of dark matter is hampered by a disk-halo degeneracy, which can possibly be broken by observations of velocity dispersions in both the MgI region and the CaII region.

  5. Environmental Effects on Late-Type Galaxies in Nearby Clusters

    CERN Document Server

    Boselli, A

    2006-01-01

    The transformations taking place in late-type galaxies in the environment of rich clusters of galaxies at z=0 are reviewed. From the handful of late-type galaxies that inhabit local clusters, whether they were formed in-situ and survived as such, avoiding transformation or even destruction or if they are newcomers that recently infall from outside, we can learn an important lesson on the latest stages of galaxy evolution. We start by reviewing the observational scenario, covering the broadest possible stretch of the electromagnetic spectrum, from the gas tracers, the star formation tracers, the old star tracers and the dust. Strong emphasis is given to the three nearby, well studied clusters Virgo, A1367 and Coma, representative of different evolutionary stages, from unrelaxed, spiral rich (Virgo) to relaxed, spiral poor clusters (Coma). We continue by providing a review of models of galaxy interactions relevant to clusters of galaxies. Prototypes of various mechanisms and processes are discussed and their ty...

  6. Star Formation and Gas Accretion in Nearby Galaxies

    CERN Document Server

    Yim, Kijeong

    2016-01-01

    In order to quantify the relationship between gas accretion and star formation, we analyse a sample of 29 nearby galaxies from the WHISP survey which contains galaxies with and without evidence for recent gas accretion. We compare combined radial profiles of FUV (GALEX) and IR 24 {\\mu}m (Spitzer) characterizing distributions of recent star formation with radial profiles of CO (IRAM, BIMA, or CARMA) and HI (WSRT) tracing molecular and atomic gas contents to examine star formation efficiencies in symmetric (quiescent), asymmetric (accreting), and interacting (tidally disturbed) galaxies. In addition, we investigate the relationship between star formation rate and HI in the outer discs for the three groups of galaxies. We confirm the general relationship between gas surface density and star formation surface density, but do not find a significant difference between the three groups of galaxies.

  7. Spherical Accretion in Nearby Weakly Active Galaxies

    CERN Document Server

    Moscibrodzka, M A

    2005-01-01

    We consider the sample of weakly active galaxies situated in 'Local Universe' collected in the paper of Pellegrini (2005) with inferred accretion efficiencies from $10^{-2}$ to $10^{-7}$. We apply a model of spherically symmetrical Bondi accretion for given parameters ($M_{BH}$,$T_{\\infty}$,$\\rho_{\\infty}$,) taken from observation. We calculate spectra emitted by the gas accreting onto its central objects using Monte Carlo method including synchrotron and bremsstrahlung photons as seed photons. We compare our results with observed nuclear X-ray luminosities $L_{X,nuc}$ (0.3-10 keV) of the sample. Model is also tested for different external medium parameters ($\\rho_{\\infty}$ and $T_{\\infty}$) and different free parameters of the model. Our model is able to explain most of the observed nuclear luminosities $L_X$ under an assumption that half of the compresion energy is transfered directly to the electrons.

  8. The Dragonfly Nearby Galaxies Survey. II. Ultra diffuse galaxies near the elliptical galaxy NGC 5485

    CERN Document Server

    Merritt, Allison; Danieli, Shany; Abraham, Roberto; Zhang, Jielai; Karachentsev, I D; Makarova, L N

    2016-01-01

    We present the unexpected discovery of four ultra diffuse galaxies (UDGs) in a group environment. We recently identified seven extremely low surface brightness galaxies in the vicinity of the spiral galaxy M101, using data from the Dragonfly Telephoto Array. The galaxies have effective radii of $10"-38"$ and central surface brightnesses of $25.6-27.7$ mag arcsec$^{-2}$ in g-band. We subsequently obtained follow-up observations with $HST$ to constrain the distances to these galaxies. Four remain persistently unresolved even with the spatial resolution of $HST$/ACS, which implies distances of $D > 17.5$ Mpc. We show that the galaxies are most likely associated with a background group at $\\sim 27$ Mpc containing the massive ellipticals NGC 5485 and NGC 5473. At this distance, the galaxies have sizes of $2.6-4.9$ kpc, and are classified as UDGs, similar to the populations that have been revealed in clusters such as Coma, Virgo and Fornax, yet even more diffuse. The discovery of four UDGs in a galaxy group demonst...

  9. Mapping Extinction and Star Formation Rates of Nearby Galaxies

    Science.gov (United States)

    Ridenour, Anthony; Takamiya, M.

    2010-01-01

    Star Formation Rate (SFR) is a physical characteristic of galaxies vital to our understanding of such problems as the evolution of the Universe. In computing SFRs obscuring dust systematically lowers them at shorter wavelengths compared to longer wavelengths. This issue of dust extinction has been handled well by multi-wavelength studies of nearby galaxies. Star Formation Rate measurements of distant galaxies are currently reliant on the emission of visible spectroscopic lines like Hα and [OII] after correction for extinction. However, if the visible light is completely obscured an incorrect assumption may be drawn; namely that there is neither SFR nor extinction. The work purposed here is to calibrate the SFR ascertained from Hα emission in nearby galaxies and compare it to radio and infrared emission. The Balmer decrement, or the ratio of Hβ to Hα emission, used to determine extinction, will also be studied and compared to infrared images. 30 nearby galaxies will be sampled and 2-D maps and Balmer decrements will be formed to do two things: measure SFRs and determine differences between Hα and infrared emission, and explore in what ways this difference corresponds with such things as the radio SFR, galaxy luminosity and morphological type. The accuracy of Hα as a SFR indicator and its determination as a sound tool in measuring SFRs of distant galaxies can both be quantified by interpreting these maps. Dr. Marianne Takamiya, the principal investigator and my mentor, secured funds through a grant to the University of Hawai'i at Hilo from The Research Corporation for Science Advancement Cottrell College Science Awards for this research.

  10. Making galaxies passive: Insights from resolved studies of nearby galaxies

    OpenAIRE

    Querejeta, Miguel

    2016-01-01

    The rapid suppression of star formation, or quenching, is thought to be an important process in the evolution of the most massive galaxies, but the mechanisms involved are still hotly debated. Here, we consider two agents that control star formation and can ultimately lead to its suppression: AGN feedback and galaxy mergers. In the first part of the thesis, we study the interplay between stellar structure, nuclear activity, and molecular gas in the context of AGN feeding and feedback. We ...

  11. A UNIVERSAL NEUTRAL GAS PROFILE FOR NEARBY DISK GALAXIES

    International Nuclear Information System (INIS)

    Based on sensitive CO measurements from HERACLES and H I data from THINGS, we show that the azimuthally averaged radial distribution of the neutral gas surface density (ΣHI+ ΣH2) in 33 nearby spiral galaxies exhibits a well-constrained universal exponential distribution beyond 0.2 × r25 (inside of which the scatter is large) with less than a factor of two scatter out to two optical radii r25. Scaling the radius to r25 and the total gas surface density to the surface density at the transition radius, i.e., where ΣHI and ΣH2 are equal, as well as removing galaxies that are interacting with their environment, yields a tightly constrained exponential fit with average scale length 0.61 ± 0.06 r25. In this case, the scatter reduces to less than 40% across the optical disks (and remains below a factor of two at larger radii). We show that the tight exponential distribution of neutral gas implies that the total neutral gas mass of nearby disk galaxies depends primarily on the size of the stellar disk (influenced to some degree by the great variability of ΣH2 inside 0.2 × r25). The derived prescription predicts the total gas mass in our sub-sample of 17 non-interacting disk galaxies to within a factor of two. Given the short timescale over which star formation depletes the H2 content of these galaxies and the large range of r25 in our sample, there appears to be some mechanism leading to these largely self-similar radial gas distributions in nearby disk galaxies.

  12. Comparing [C II] , HI, and CO Dynamics of Nearby Galaxies

    OpenAIRE

    Blok, W.J.G. de; Walter, F.; Smith, J. -D. T.; Herrera-Camus, R.; Bolatto, A. D.; Requena-Torres, M. A.; Crocker, A. F.; Croxall, K. V.; Kennicutt, R.C.; Koda, J.; Armus, L.; Boquien, M.; Dale, D.; Kreckel, K.; Meidt, S.

    2016-01-01

    The H I and CO components of the interstellar medium (ISM) are usually used to derive the dynamical mass M_(dyn) of nearby galaxies. Both components become too faint to be used as a tracer in observations of high-redshift galaxies. In those cases, the 158 μm line of atomic carbon ([C II]) may be the only way to derive M_(dyn). As the distribution and kinematics of the ISM tracer affects the determination of M_(dyn), it is important to quantify the relative distributions of H I, CO, and [C II]...

  13. From nearby to distant galaxies: kinematical and dynamical studies

    CERN Document Server

    Epinat, Benoit

    2009-01-01

    Kinematical studies of low and high redshift galaxies enables to probe galaxy formation and evolution scenarios. Integral field spectroscopy is a powerful tool to study with accuracy nearby galaxies kinematics. Recent observations also gives a new 2D vision of high redshift galaxies kinematics. This work mostly relies on the kinematical sample of galaxies GHASP. This control sample, composed of 203 local spiral and irregular galaxies in low density environments observed with Fabry-Perot techniques in the Ha line (6563 A), is by now the largest sample of Fabry-Perot data. After a revue on Fabry-Perot interferometry and a presentation of new data reduction procedures, my implications on both 3D-NTT Fabry-Perot instrument and the wide field spectrograph project (WFSpec) for galaxy evolution study with the european ELT are developed. The second section is dedicated to GHASP data. This sample have been fully reduced and analysed using new methods. The kinematical analysis of 2D kinematical maps has been undertaken...

  14. Starbursts versus Truncated Star Formation in Nearby Clusters of Galaxies

    CERN Document Server

    Rose, J A; Caldwell, N; Chaboyer, B; Rose, James A.; Gaba, Alejandro E.; Caldwell, Nelson; Chaboyer, Brian

    2001-01-01

    We present long-slit spectroscopy, B and R bandpass imaging, and 21 cm observations of a sample of early-type galaxies in nearby clusters which are known to be either in a star-forming phase or to have had star formation which recently terminated. From the long-slit spectra, obtained with the Blanco 4-m telescope, we find that emission lines in the star-forming cluster galaxies are significantly more centrally concentrated than in a sample of field galaxies. The broadband imaging reveals that two currently star-forming early-type galaxies in the Pegasus I cluster have blue nuclei, again indicating that recent star formation has been concentrated. In contrast, the two galaxies for which star formation has already ended show no central color gradient. The Pegasus I galaxy with the most evident signs of ongoing star formation (NGC7648), exhibits signatures of a tidal encounter. Neutral hydrogen observations of that galaxy with the Arecibo radiotelescope reveal the presence of ~4 x 10^8 solar masses of HI. Arecib...

  15. An IceCube Search for Dark Matter Annihilation in nearby Galaxies and Galaxy Clusters

    CERN Document Server

    Aartsen, M G; Abdou, Y; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Beatty, J J; Bechet, S; Tjus, J Becker; Becker, K -H; Benabderrahmane, M L; BenZvi, S; Berghaus, P; Berley, D; Bernardini, E; Bernhard, A; Bertrand, D; Besson, D Z; Binder, G; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohaichuk, S; Bohm, C; Bose, D; Böser, S; Botner, O; Brayeur, L; Bretz, H -P; Brown, A M; Bruijn, R; Brunner, J; Carson, M; Casey, J; Casier, M; Chirkin, D; Christov, A; Christy, B; Clark, K; Clevermann, F; Coenders, S; Cohen, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; Day, M; De Clercq, C; De Ridder, S; Desiati, P; de Vries, K D; de With, M; DeYoung, T; D'\\iaz-Vélez, J C; Dunkman, M; Eagan, R; Eberhardt, B; Eisch, J; Ellsworth, R W; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Golup, G; Gonzalez, J G; Goodman, J A; Góra, D; Grandmont, D T; Grant, D; Groß, A; Ha, C; Ismail, A Haj; Hallen, P; Hallgren, A; Halzen, F; Hanson, K; Heereman, D; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Jagielski, K; Japaridze, G S; Jero, K; Jlelati, O; Kaminsky, B; Kappes, A; Karg, T; Karle, A; Kelley, J L; Kiryluk, J; Kläs, J; Klein, S R; Köhne, J -H; Kohnen, G; Kolanosk, H; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Krings, K; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Landsman, H; Larson, M J; Lesiak-Bzdak, M; Leuermann, M; Leute, J; Lünemann, J; Macías, O; Madsen, J; Maggi, G; Maruyama, R; Mase, K; Matis, H S; McNally, F; Meagher, K; Merck, M; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Niederhausen, H; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Omairat, A; O'Murchadha, A; Paul, L; Pepper, J A; Heros, C Pérez de los; Pfendner, C; Pieloth, D; Pinat, E; Posselt, J; Price, P B; Przybylski, G T; Rädel, L; Rameez, M; Rawlins, K; Redl, P; Reimann, R; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Rodrigues, J P; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Salameh, T; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schöneberg, S; Schönwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Sestayo, Y; Seunarine, S; Shanidze, R; Sheremata, C; Smith, M W E; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stasik, A; Stezelberger, T; Stokstad, R G; Stößl, A; Strahler, E A; Ström, R; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Tepe, A; Ter-Antonyan, S; Tešić, G; Tilav, S; Toale, P A; Toscano, S; Unger, E; Usner, M; Vallecorsa, S; van Eijndhoven, N; Van Overloop, A; van Santen, J; Vehring, M; Voge1, M; Vraeghe, M; Walck, C; Waldenmaier, T; Wallraff, M; Weaver, Ch; Wellons, M; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zierke, S; Zoll, M

    2013-01-01

    We present the results of a first search for self-annihilating dark matter in nearby galaxies and galaxy clusters using a sample of high energy neutrinos acquired in 339.8 days of livetime during 2009/10 with the IceCube neutrino observatory in its 59-string configuration. The targets of interest include the Virgo and Coma galaxy clusters, the Andromeda galaxy and several dwarf galaxies. We obtain upper limits on the cross section as function of the WIMP mass between 300 GeV and 100 TeV for the annihilation into b bbar, W+W-, \\tau+\\tau-, \\mu+\\mu- and \

  16. The Mitchell Spectrograph: Studying Nearby Galaxies with the VIRUS Prototype

    Directory of Open Access Journals (Sweden)

    Guillermo A. Blanc

    2013-01-01

    Full Text Available The Mitchell Spectrograph (a.k.a. VIRUS-P on the 2.7 m Harlan J. Smith telescope at McDonald Observatory is currently the largest field of view (FOV integral field unit (IFU spectrograph in the world (1.7′×1.7′. It was designed as a prototype for the highly replicable VIRUS spectrograph which consists of a mosaic of IFUs spread over a 16′ diameter FOV feeding 150 spectrographs similar to the Mitchell. VIRUS will be deployed on the 9.2 meter Hobby-Eberly Telescope (HET and will be used to conduct the HET Dark Energy Experiment (HETDEX. Since seeing first light in 2007 the Mitchell Spectrograph has been widely used, among other things, to study nearby galaxies in the local universe where their internal structure and the spatial distribution of different physical parameters can be studied in great detail. These observations have provided important insight into many aspects of the physics behind the formation and evolution of galaxies and have boosted the scientific impact of the 2.7 meter telescope enormously. Here I review the contributions of the Mitchell Spectrograph to the study of nearby galaxies, from the investigation the spatial distribution of dark matter and the properties of supermassive black holes, to the studies of the process of star formation and the chemical composition of stars and gas in the ISM, which provide important information regarding the formation and evolution of these systems. I highlight the fact that wide field integral field spectrographs on small and medium size telescopes can be powerful cost effective tools to study the astrophysics of galaxies. Finally I briefly discuss the potential of HETDEX for conducting studies on nearby galaxies. The survey parameters make it complimentary and competitive to ongoing and future surveys like SAMI and MANGA.

  17. The Neutral ISM in Nearby Luminous Compact Blue Galaxies

    CERN Document Server

    Garland, C A; Williams, J P; Guzmán, R; Castander, F J

    2003-01-01

    We observed 20 nearby Luminous Compact Blue Galaxies (LCBGs) in HI and CO(J=2-1) with the GBT and JCMT. These ~L^star galaxies are blue, high surface brightness, starbursting, high metallicity galaxies with an underlying older stellar population. They are common at z~1, but rare in the local Universe. It has been proposed that intermediate redshift LCBGs may be the progenitors of local dwarf ellipticals or low luminosity spirals, or that they may be more massive disks forming from the center outward to become L^star galaxies. To discriminate among various possible evolutionary scenarios, we have measured the dynamical masses and gas depletion time scales of this sample of nearby LCBGs. We find that local LCBGs span a wide range of dynamical masses, from 4 x 10^9 to 1 x 10^11 M_solar (measured within R_25). Molecular gas in local LCBGs is depleted quite quickly, in 30 to 200 million years. The molecular plus atomic gas is depleted in 30 million to 10 billion years; however, ~80% of the local LCBGs deplete thei...

  18. Spiral structure in nearby galaxies II. comparative analysis and conclusions

    CERN Document Server

    Kendall, S; Kennicutt, R C

    2014-01-01

    This paper presents a detailed analysis of two-armed spiral structure in a sample of galax- ies from the Spitzer Infrared Nearby Galaxies Survey (SINGS), with particular focus on the relationships between the properties of the spiral pattern in the stellar disc and the global struc- ture and environment of the parent galaxies. Following Paper I we have used a combination of Spitzer Space Telescope mid-infrared imaging and visible multi-colour imaging to isolate the spiral pattern in the underlying stellar discs, and we examine the systematic behaviours of the observed amplitudes and shapes (pitch angles) of these spirals. In general, spiral morphology is found to correlate only weakly at best with morphological parameters such as stellar mass, gas fraction, disc/bulge ratio, and vflat. In contrast to weak correlations with galaxy structure a strong link is found between the strength of the spiral arms and tidal forcing from nearby companion galaxies. This appears to support the longstanding suggestion that ei...

  19. HI emission and absorption in nearby, gas-rich galaxies

    CERN Document Server

    Reeves, S N; Allison, J R; Koribalski, B S; Curran, S J; Pracy, M B

    2015-01-01

    We present the results of a targeted search for intervening HI absorption in six nearby, gas-rich galaxies using the Australia Telescope Compact Array (ATCA). The sightlines searched have impact parameters of 10-20 kpc. By targeting nearby galaxies we are also able to map their HI emission, allowing us to directly relate the absorption-line detection rate to the extended HI distribution. The continuum sightlines intersect the HI disk in four of the six galaxies, but no intervening absorption was detected. Of these four galaxies, we find that three of the non-detections are the result of the background source being too faint. In the fourth case we find that the ratio of the spin temperature to the covering factor ($T_{\\mathrm{S}}/f$) must be much higher than expected ($\\gtrsim$5700 K) in order to explain the non-detection. We discuss how the structure of the background continuum sources may have affected the detection rate of HI absorption in our sample, and the possible implications for future surveys. Future...

  20. Radial gas motions in The HI Nearby Galaxy Survey (THINGS)

    CERN Document Server

    Schmidt, Tobias M; Klessen, Ralf S; de Blok, W J G

    2016-01-01

    The study of 21cm line observations of atomic hydrogen allows detailed insight into the kinematics of spiral galaxies. We use sensitive high-resolution VLA data from The HI Nearby Galaxy Survey (THINGS) to search for radial gas flows primarily in the outer parts (up to $3\\times r_{25}$) of ten nearby spiral galaxies. Inflows are expected to replenish the gas reservoir and fuel star formation under the assumption that galaxies evolve approximately in steady state. We carry out a detailed investigation of existing tilted ring fitting schemes and discover systematics that can hamper their ability to detect signatures of radial flows. We develop a new Fourier decomposition scheme that fits for rotational and radial velocities and simultaneously determines position angle and inclination as a function of radius. Using synthetic velocity fields we show that our novel fitting scheme is less prone to such systematic errors and that it is well suited to detect radial inflows in disks. We apply our fitting scheme to ten...

  1. The Origin of Neutral Hydrogen Clouds in Nearby Galaxy Groups: Exploring the Range Of Galaxy Interactions

    CERN Document Server

    Chynoweth, Katie M; Polisensky, Emil; Langston, Glen

    2011-01-01

    We combine high resolution N-body simulations with deep observations of neutral hydrogen (HI) in nearby galaxy groups in order to explore two well-known theories of HI cloud formation: HI stripping by galaxy interactions and dark matter minihalos with embedded HI gas. This paper presents new data from three galaxy groups, Canes Venatici I, NGC 672, and NGC 45, and assembles data from our previous galaxy group campaign to generate a rich HI cloud archive to compare to our simulated data. We find no HI clouds in the Canes Venatici I, NGC 672, or NGC 45 galaxy groups. We conclude that HI clouds in our detection space are most likely to be generated through recent, strong galaxy interactions. We find no evidence of HI clouds associated with dark matter halos above M_HI = 10^6 M_Sun, within +/- 700 km/s of galaxies, and within 50 kpc projected distance of galaxies.

  2. Galaxy Distances in the Nearby Universe Corrections For Peculiar Motions

    CERN Document Server

    Marinoni, C; Giuricin, G; Costantini, B

    1998-01-01

    By correcting the redshift--dependent distances for peculiar motions through a number of peculiar velocity field models, we recover the true distances of a wide, all-sky sample of nearby galaxies (~ 6400 galaxies with velocities cz<5500 km/s), which is complete up to the blue magnitude B=14 mag. Relying on catalogs of galaxy groups, we treat ~2700 objects as members of galaxy groups and the remaining objects as field galaxies. We model the peculiar velocity field using: i) a cluster dipole reconstruction scheme; ii) a multi--attractor model fitted to the Mark II and Mark III catalogs of galaxy peculiar velocities. According to Mark III data the Great Attractor has a smaller influence on local dynamics than previously believed, whereas the Perseus-Pisces and Shapley superclusters acquire a specific dynamical role. Remarkably, the Shapley structure, which is found to account for nearly half the peculiar motion of the Local Group, is placed by Mark III data closer to the zone of avoidance with respect to its ...

  3. Scaling Relations between Gas and Star Formation in Nearby Galaxies

    CERN Document Server

    Bigiel, F; Walter, F

    2010-01-01

    High resolution, multi-wavelength maps of a sizeable set of nearby galaxies have made it possible to study how the surface densities of HI, H2 and star formation rate (Sigma_HI, Sigma_H2, Sigma_SFR) relate on scales of a few hundred parsecs. At these scales, individual galaxy disks are comfortably resolved, making it possible to assess gas-SFR relations with respect to environment within galaxies. Sigma_H2, traced by CO intensity, shows a strong correlation with Sigma_SFR and the ratio between these two quantities, the molecular gas depletion time, appears to be constant at about 2Gyr in large spiral galaxies. Within the star-forming disks of galaxies, Sigma_SFR shows almost no correlation with Sigma_HI. In the outer parts of galaxies, however, Sigma_SFR does scale with Sigma_HI, though with large scatter. Combining data from these different environments yields a distribution with multiple regimes in Sigma_gas - Sigma_SFR space. If the underlying assumptions to convert observables to physical quantities are m...

  4. H{\\alpha} Imaging of Nearby Seyfert Host Galaxies

    CERN Document Server

    Theios, R L; Ross, N R

    2016-01-01

    We used narrowband interference filters with the CCD imaging camera on the Nickel 1.0 meter telescope at Lick Observatory to observe 31 nearby (z < 0.03) Seyfert galaxies in the 12 {\\mu}m Active Galaxy Sample. We obtained pure emission line images of each galaxy in order to separate H{\\alpha} emission from the nucleus from that of the host galaxy. The extended H{\\alpha} emission is expected to be powered by newly formed hot stars, and correlates well with other indicators of current star formation in these galaxies: 7.7 {\\mu}m PAH, far-infrared, and radio luminosity. Relative to what would be expected from recent star formation, there is a 0.8 dex excess of radio emission in our Seyfert galaxies. The nuclear H{\\alpha} luminosity is dominated by the AGN, and is correlated with the hard X-ray luminosity. There is an upward offset of 1 dex in this correlation for the Seyfert 1s due to a strong contribution from the Broad Line Region. We found a correlation between star formation rate and AGN luminosity. In sp...

  5. Metallicities of galaxies in the nearby Lynx-Cancer void

    CERN Document Server

    Kniazev, A; Tepliakova, A; Burenkov, A

    2010-01-01

    Does the void environment have a sizable effect on the evolution of dwarf galaxies? If yes, the best probes should be the most fragile least massive dwarfs. We compiled a sample of about one hundred dwarfs with M_B in the range -12 to -18 mag, falling within the nearby Lynx-Cancer void. The goal is to study their evolutionary parameters -- gas metallicity and gas mass-fraction, and to address the epoch of the first substantial episode of Star Formation. Here we present and discuss the results of O/H measurements in 38 void galaxies, among which several the most metal-poor galaxies are found with the oxygen abundances of 12+log(O/H)=7.12-7.3 dex.

  6. FIR colours and SEDs of nearby galaxies observed with Herschel

    CERN Document Server

    Boselli, A; Buat, V; Cortese, L; Auld, R; Baes, M; Bendo, G J; Bianchi, S; Bock, J; Bomans, D J; Bradford, M; Castro-Rodriguez, N; Chanial, P; Charlot, S; Clemens, M; Clements, D; Corbelli, E; Cooray, A; Cormier, D; Dariush, A; Davies, J; De Looze, I; Alighieri, S di Serego; Dwek, E; Eales, S; Elbaz, D; Fadda, D; Fritz, J; Galametz, M; Galliano, F; Garcia-Appadoo, D A; Gavazzi, G; Gear, W; Giovanardi, C; Glenn, J; Gomez, H; Griffin, M; Grossi, M; Hony, S; Hughes, T M; Hunt, L; Isaak, K; Jones, A; Levenson, L; Lu, N; Madden, S C; O'Halloran, B; Okumura, K; Oliver, S; Page, M; Panuzzo, P; Papageorgiou, A; Parkin, T; Perez-Fournon, I; Pierini, D; Pohlen, M; Rangwala, N; Rigby, E; Roussel, H; Rykala, A; Sabatini, S; Sacchi, N; Sauvage, M; Schulz, B; Schirm, M; Smith, M W L; Spinoglio, L; Stevens, J; Sundar, S; Symeonidis, M; Trichas, M; Vaccari, M; Verstappen, J; Vigroux, L; Vlahakis, C; Wilson, C; Wozniak, H; Wright, G; Xilouris, E M; Zeilinger, W; Zibetti, S

    2010-01-01

    We present infrared colours (in the 25-500 mic spectral range) and UV to radio continuum spectral energy distributions of a sample of 51 nearby galaxies observed with SPIRE on Herschel. The observed sample includes all morphological classes, from quiescent ellipticals to active starbursts. Active galaxies have warmer colour temperatures than normal spirals. In ellipticals hosting a radio galaxy, the far-infrared (FIR) emission is dominated bynthe synchrotron nuclear emission. The colour temperature of the cold dust is higher in quiescent E-S0a than in star-forming systems probably because of the different nature of their dust heating sources (evolved stellar populations, X-ray, fast electrons) and dust grain properties. In contrast to the colour temperature of the warm dust, the f350/f500 index sensitive to the cold dust decreases with star formation and increases with metallicity, suggesting an overabundance of cold dust or an emissivity parameter beta<2 in low metallicity, active systems.

  7. Planck Early Results: The Planck View of Nearby Galaxies

    CERN Document Server

    Ade, P A R; Arnaud, M; Ashdown, M; Aumont, J; Baccigalupi, C; Balbi, A; Banday, A J; Barreiro, R B; Bartlett, J G; Battaner, E; Benabed, K; Benoît, A; Bernard, J -P; Bersanelli, M; Bhatia, R; Bock, J J; Bonaldi, A; Bond, J R; Borrill, J; Bouchet, F R; Bucher, M; Burigana, C; Cabella, P; Cardoso, J -F; Catalano, A; Cayón, L; Challinor, A; Chamballu, A; Chary, R -R; Chiang, L -Y; Christensen, P R; Clements, D L; Colombi, S; Couchot, F; Coulais, A; Crill, B P; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Gasperis, G; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Désert, F -X; Dickinson, C; Dole, H; Donzelli, S; Doré, O; Dörl, U; Douspis, M; Dupac, X; Efstathiou, G; En\\sslin, T A; Finelli, F; Forni, O; Frailis, M; Franceschi, E; Galeotta, S; Ganga, K; Giard, M; Giardino, G; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Hansen, F K; Harrison, D; Helou, G; Henrot-Versillé, S; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hovest, W; Hoyland, R J; Huffenberger, K M; Jaffe, A H; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knox, L; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Leach, S; Leonardi, R; Linden-V\\ornle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; MacTavish, C J; Madden, S; Maffei, B; Maino, D; Mandolesi, N; Mann, R; Maris, M; Martínez-González, E; Masi, S; Matarrese, S; Matthai, F; Mazzotta, P; Melchiorri, A; Mendes, L; Mennella, A; Miville-Deschênes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, A; Naselsky, P; Natoli, P; Netterfield, C B; N\\orgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; Osborne, S; Pajot, F; Partridge, B; Pasian, F; Patanchon, G; Peel, M; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Poutanen, T; Prézeau, G; Prunet, S; Puget, J -L; Reach, W T; Rebolo, R; Reinecke, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Rowan-Robinson, M; Rubi\; Rusholme, B; Sandri, M; Savini, G; Scott, D; Seiffert, M D; Shellard, P; Smoot, G F; Starck, J -L; Stivoli, F; Stolyarov, V; Sudiwala, R; Sygnet, J -F; Tauber, J A; Terenzi, L; Toffolatti, L; Tomasi, M; Torre, J -P; Tristram, M; Tuovinen, J; Türler, M; Umana, G; Valenziano, L; Varis, J; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Yvon, D; Zacchei, A; Zonca, A

    2011-01-01

    The all-sky coverage of the Planck Early Release Compact Source Catalogue (ERCSC) provides an unsurpassed survey of galaxies at submillimetre (submm) wavelengths, representing a major improvement in the numbers of galaxies detected, as well as the range of far-IR/submm wavelengths over which they have been observed. We here present the first results on the properties of nearby galaxies using these data. We match the ERCSC catalogue to IRAS-detected galaxies in the Imperial IRAS Faint Source Redshift Catalogue (IIFSCz), so that we can measure the spectral energy distributions (SEDs) of these objects from 60 to 850 microns. This produces a list of 1717 galaxies with reliable associations between Planck and IRAS, from which we select a subset of 468 for SED studies, namely those with strong detections in the three highest frequency Planck bands and no evidence of cirrus contamination. The SEDs are fitted using parametric dust models to determine the range of dust temperatures and emissivities. We find evidence f...

  8. MaNGA: Mapping Nearby Galaxies at Apache Point Observatory

    Science.gov (United States)

    Bundy, Kevin

    2015-04-01

    I describe a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory). One of three core programs in the 6-year SDSS-IV project† that began on July 1st, 2014, MaNGA will deploy 17 fiber-bundle IFUs across the Sloan 2.5m Telescope's 3 degree field-of-view, targeting a mass-selected sample with a median redshift of 0.03, typical spatial resolution of 1-2 kpc, and a per-fiber signal-to-noise ratio of 4-8 in the outskirts of target galaxies. For each galaxy in the sample, MaNGA will provide maps and measured gradients of the composition and dynamics of both stars and gas. I discuss early results that highlight MaNGA's potential to shed light on the ionization and chemical enrichment of gas in galaxies, spatial patterns in their star formation histories, and the internal makeup of stellar populations. MaNGA's unprecedented data set will not only provide powerful new insight on galaxy formation and evolution but will serve as a valuable benchmark for future high-z observations from large telescopes and space-based facilities.

  9. Black Holes at the Centers of Nearby Dwarf Galaxies

    CERN Document Server

    Moran, Edward C; Sugarman, Hannah R; Velez, Darik O; Eracleous, Michael

    2014-01-01

    Using a distance-limited portion of the Sloan Digital Sky Survey (SDSS) Data Release 7, we have identified 28 active galactic nuclei (AGNs) in nearby (d < 80 Mpc) low-mass, low-luminosity dwarf galaxies. The accreting objects at the galaxy centers are expected to be intermediate-mass black holes (IMBHs) with M_BH < 1e6 M_sun. The AGNs were selected using several optical emission-line diagnostics after careful modeling of the continuum present in the spectra. We have limited our survey to objects with spectral characteristics similar to those of Seyfert nuclei, excluding emission-line galaxies with ambiguous spectra that could be powered by stellar processes. The host galaxies in our sample are thus the least massive objects in the very local universe certain to contain central black holes. Given our focus on the nearest objects included in the SDSS, our survey is more sensitive to low-luminosity emission than previous optical searches for AGNs in low-mass galaxies. The [O III] lambda5007 luminosities of...

  10. The Nuclear Activities of Nearby S0 Galaxies

    CERN Document Server

    Xiao, Mengyuan; Chen, Yanmei; Zhou, Luwenjia

    2016-01-01

    We present a study of nuclear activities in nearby S0 galaxies. After cross-matching the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) with the Third Reference Catalog of Bright Galaxies (RC3) and visually checking the SDSS images, we derive a sample of 583 S0 galaxies with the central spectrophotometric information. In order to separate nebular emission lines from the underlying stellar contribution, we fit the stellar population model to the SDSS spectra of these S0 galaxies. According to the BPT diagram, we find that $8\\%$ of S0 galaxies show central star-forming activity, while the fractions of Seyfert, Composite and LINERs are 2\\%, 8\\%, and 21.4\\%, respectively. We also find that star-forming S0s have the lowest stellar masses, over one magnitude lower than the others, and that the active S0s locate mainly in the sparse environment, while the normal S0s in the dense environment, which might suggest that the environment plays an important role in quenching star formation and/or AGN activity in S0 gal...

  11. Lyman alpha Emitting Galaxies in the Nearby Universe

    CERN Document Server

    Hayes, Matthew

    2015-01-01

    The Lya emission line of HI is intrinsically the brightest feature in the spectrum of astrophysical nebulae, making it a very attractive observational tool with which to survey galaxies. Moreover as a UV resonance line, Lya possesses several unique characteristics that make it useful to study the ISM and ionizing stellar population at all cosmic epochs. In this review I present a summary of Lya observations of galaxies in the nearby universe. At UV magnitudes reachable with current facilities, only ~5% of the local galaxy population shows a Lya equivalent width (EW_Lya) that exceeds 20\\AA. This fraction increases dramatically at higher z, but only in the local universe can we study galaxies in detail and assemble unprecedented multi-wavelength datasets. I discuss many local Lya observations, showing that when galaxies show net Lya emission, they ubiquitously produce large halos of scattered Lya, that dominate the integrated luminosity. We discuss how global EW_Lya and the Lya escape fraction (fescLya) are hig...

  12. Radial Star Formation Histories in Fifteen Nearby Galaxies

    CERN Document Server

    Dale, Daniel A; Egan, Arika A; Hatlestad, Alan J; Herzog, Laura J; Leung, Andrew S; McLane, Jacob N; Phenicie, Christopher; Roberts, Jareth S; Barnes, Kate L; Boquien, Mederic; Calzetti, Daniela; Cook, David O; Kobulnicky, Henry A; Staudaher, Shawn M; van Zee, Liese

    2015-01-01

    New deep optical and near-infrared imaging is combined with archival ultraviolet and infrared data for fifteen nearby galaxies mapped in the Spitzer Extended Disk Galaxy Exploration Science survey. These images are particularly deep and thus excellent for studying the low surface brightness outskirts of these disk-dominated galaxies with stellar masses ranging between 10^8 and 10^11 Msun. The spectral energy distributions derived from this dataset are modeled to investigate the radial variations in the galaxy colors and star formation histories. Taken as a whole, the sample shows bluer and younger stars for larger radii until reversing near the optical radius, whereafter the trend is for redder and older stars for larger galacto-centric distances. These results are consistent with an inside-out disk formation scenario coupled with an old stellar outer disk population formed through radial migration and/or the cumulative history of minor mergers and accretions of satellite dwarf galaxies. However, these trends...

  13. Ultraviolet Radiative Transfer Modeling of Nearby Galaxies with Extraplanar Dusts

    CERN Document Server

    Shinn, Jong-Ho

    2015-01-01

    In order to examine their relation to the host galaxy, the extraplanar dust of six nearby galaxies are modeled, employing a three dimensional Monte Carlo radiative transfer code. The targets are from the highly-inclined galaxies that show dust-scattered ultraviolet halos, and the archival Galaxy Evolution Explorer FUV band images were fitted with the model. The observed images are in general well reproduced by two dust layers and one light-source layer, whose vertical and radial distributions have exponential profiles. We obtained several important physical parameters, such as star formation rate (SFR_UV), face-on optical depth, and scale-heights. Three galaxies (NGC 891, NGC 3628, and UGC 11794) show clear evidence for the existence of extraplanar dust layer. However, it is found that the rest three targets (IC 5249, NGC 24, and NGC 4173) do not necessarily need a thick dust disk to model the ultraviolet (UV) halo, because its contribution is too small and the UV halo may be caused by the wing part of the GA...

  14. Infrared colour properties of nearby radio-luminous galaxies

    CERN Document Server

    Yang, Xiao-hong; Huang, Yan

    2015-01-01

    By combining the data of the Two Micron All Sky Survey (2MASS), the Wide Field Infrared Survey Explorer (WISE) and the Akari satellite, we study the infrared colour properties of a sample of 2712 nearby radio-luminous galaxies (RLGs). These RLGs are divided into radio-loud (RL) active galactic nuclei (AGNs), mainly occurring at redshifts of $0.05$ 3.0. We also analyse the MIR colours of RL AGNs divided into low- and high-excitation radio galaxies (LERGs and HERGs, respectively). The ([3.4]-[4.6])$-$([4.6]-[12]) diagram clearly shows separate distributions of LERGs and HERGs and a region of overlap, which suggests that LERGs and HERGs have different MIR properties. LERGs are responsible for the double-core distribution of RL AGNs on the ([3.4]-[4.6])$-$([4.6]-[12]) diagram. In addition, we also suggest 90$-$140$\\mu$m band spectral index $\\alpha(90,140)<-1.4$ as a criterion of selecting nearby active galaxies with non-thermal emissions at FIR wavelengths.

  15. Comparing [CII], HI, and CO dynamics of nearby galaxies

    CERN Document Server

    de Blok, W J G; Smith, J -D T; Herrera-Camus, R; Bolatto, A D; Requena-Torres, M A; Crocker, A F; Croxall, K V; Kennicutt, R C; Koda, J; Armus, L; Boquien, M; Dale, D; Kreckel, K; Meidt, S

    2016-01-01

    The HI and CO components of the interstellar medium (ISM) are usually used to derive the dynamical mass M_dyn of nearby galaxies. Both components become too faint to be used as a tracer in observations of high-redshift galaxies. In those cases, the 158 $\\mu$m line of atomic carbon [CII] may be the only way to derive M_dyn. As the distribution and kinematics of the ISM tracer affects the determination of M_dyn, it is important to quantify the relative distributions of HI, CO and [CII]. HI and CO are well-characterised observationally, however, for [CII] only very few measurements exist. Here we compare observations of CO, HI, and [CII] emission of a sample of nearby galaxies, drawn from the HERACLES, THINGS and KINGFISH surveys. We find that within R_25, the average [CII] exponential radial profile is slightly shallower than that of the CO, but much steeper than the HI distribution. This is also reflected in the integrated spectrum ("global profile"), where the [CII] spectrum looks more like that of the CO tha...

  16. The Effect of Nearby Voids on Galaxy Number Counts

    CERN Document Server

    Bucklein, Brian K; Hintz, Eric G

    2016-01-01

    The size, shape and degree of emptiness of void interiors sheds light on the details of galaxy formation. A particularly interesting question is whether void interiors are completely empty or contain a dwarf population. However the nearby voids that are most conducive for dwarf searches have large angular diameters, on the order of a steradian, making it difficult to redshift-map a statistically significant portion of their volume to the magnitude limit of dwarf galaxies. As part of addressing this problem, we investigate here the usefulness of number counts in establishing the best locations to search inside nearby (d < 300 Mpc) galaxy voids, utilizing Wolf plots of log(n < m) vs. m as the basic diagnostic. To illustrate expected signatures, we consider the signature of three void profiles, "cut out", "built up", and "universal profile" carved into Monte-Carlo Schechter function models. We then investigate the signatures of voids in the Millennium Run dark matter simulation and the Sloan Digital Sky Su...

  17. Comparing [C II] , HI, and CO Dynamics of Nearby Galaxies

    Science.gov (United States)

    de Blok, W. J. G.; Walter, F.; Smith, J.-D. T.; Herrera-Camus, R.; Bolatto, A. D.; Requena-Torres, M. A.; Crocker, A. F.; Croxall, K. V.; Kennicutt, R. C.; Koda, J.; Armus, L.; Boquien, M.; Dale, D.; Kreckel, K.; Meidt, S.

    2016-08-01

    The H i and CO components of the interstellar medium (ISM) are usually used to derive the dynamical mass {M}{{dyn}} of nearby galaxies. Both components become too faint to be used as a tracer in observations of high-redshift galaxies. In those cases, the 158 μm line of atomic carbon ([C ii]) may be the only way to derive {M}{{dyn}}. As the distribution and kinematics of the ISM tracer affects the determination of {M}{{dyn}}, it is important to quantify the relative distributions of H i, CO, and [C ii]. H i and CO are well-characterized observationally, however, for [C ii] only very few measurements exist. Here we compare observations of CO, H i, and [C ii] emission of a sample of nearby galaxies, drawn from the HERACLES, THINGS, and KINGFISH surveys. We find that within R 25, the average [C ii] exponential radial profile is slightly shallower than that of the CO, but much steeper than the H i distribution. This is also reflected in the integrated spectrum (“global profile”), where the [C ii] spectrum looks more like that of the CO than that of the H i. For one galaxy, a spectrally resolved comparison of integrated spectra was possible; other comparisons were limited by the intrinsic line-widths of the galaxies and the coarse velocity resolution of the [C ii] data. Using high-spectral-resolution SOFIA [C ii] data of a number of star forming regions in two nearby galaxies, we find that their [C ii] linewidths agree better with those of the CO than the H i. As the radial extent of a given ISM tracer is a key input in deriving {M}{{dyn}} from spatially unresolved data, we conclude that the relevant length-scale to use in determining {M}{{dyn}} based on [C ii] data, is that of the well-characterized CO distribution. This length scale is similar to that of the optical disk.

  18. Understanding the Structure and Evolution of Nearby Disk Galaxies

    Science.gov (United States)

    Zheng, Zheng

    2014-01-01

    In order to understand the structure and evolution of disk galaxies, we studied the stellar and gaseous components as well as the star formation rate in nearby disk galaxies. We used PS1 medium deep survey images to derive five-band (grizy) surface brightness profiles down to 30 ABmag/arcsec^2 for about 700 galaxies. From these stellar mass and mass-to-light ratio radial profiles are derived. The stellar mass radial profiles tend to bend-up at large radii, this often traces an extended old stellar population. The mass-to-light ratio profiles tend to rise outside the r25 radii. We also find a larger fraction of up-bending surface brightness profiles than Polen & Trujillo (2006). This may be because their sample is biased towards low surface brightness galaxies. We used HIPASS data as well as VLA HI 21cm data to study the gas component and dynamics of disk galaxies. We used the GALEX UV images to study the star formation of a HI-selected star-forming sample of about 400 galaxies, compiling a database of FUV and NUV radial profiles and related parameters. We used this to study the star forming efficiency (SFE, star formation rate per unit area divided by gas surface mass density) of the sample galaxies. We found that the UV based SFE has a tighter relationship with HI mass than an H_alpha based SFE as typically used in previous studies and the UV SFE is flat across wide range of stellar mass. We constructed a simple model to predict the distribution of interstellar medium and star formation rate in an equilibrium disk with constant two-fluid Toomre Q. This model can reproduces the SFE relations we derived.

  19. Resolving the Milky Way and Nearby Galaxies with WFIRST

    Science.gov (United States)

    Kalirai, Jasonjot

    High-resolution studies of nearby stellar populations have served as a foundation for our quest to understand the nature of galaxies. Today, studies of resolved stellar populations constrain fundamental relations -- such as the initial mass function of stars, the time scales of stellar evolution, the timing of mass loss and amount of energetic feedback, the color-magnitude relation and its dependency on age and metallicity, the stellar-dark matter connection in galaxy halos, and the build up of stellar populations over cosmic time -- that represent key ingredients in our prescription to interpret light from the Universe and to measure the physical state of galaxies. More than in any other area of astrophysics, WFIRST will yield a transformative impact in measuring and characterizing resolved stellar populations in the Milky Way and nearby galaxies. The proximity and level of detail that such populations need to be studied at directly map to all three pillars of WFIRST capabilities - sensitivity from a 2.4 meter space based telescope, resolution from 0.1" pixels, and large 0.3 degree field of view from multiple detectors. Our WFIRST GO Science Investigation Team (F) will develop three WFIRST (notional) GO programs related to resolved stellar populations to fully stress WFIRST's Wide Field Instrument. The programs will include a Survey of the Milky Way, a Survey of Nearby Galaxy Halos, and a Survey of Star-Forming Galaxies. Specific science goals for each program will be validated through a wide range of observational data sets, simulations, and new algorithms. As an output of this study, our team will deliver optimized strategies and tools to maximize stellar population science with WFIRST. This will include: new grids of IR-optimized stellar evolution and synthetic spectroscopic models; pipelines and algorithms for optimal data reduction at the WFIRST sensitivity and pixel scale; wide field simulations of MW environments and galaxy halos; cosmological simulations

  20. Magnetic fields in nearby normal galaxies: Energy equipartition

    OpenAIRE

    Basu, Aritra; Roy, Subhashis

    2013-01-01

    We present maps of total magnetic field using 'equipartition' assumptions for five nearby normal galaxies at sub-kpc spatial resolution. The mean magnetic field is found to be ~11 \\mu G. The field is strongest near the central regions where mean values are ~20--25 \\mu G and falls to ~15 \\mu G in disk and ~10 \\mu G in the outer parts. There is little variation in the field strength between arm and interarm regions, such that, in the interarms, the field is < 20 percent weaker than in the arms....

  1. Full stellar kinematical profiles of central parts of nearby galaxies

    Science.gov (United States)

    Vudragović, A.; Samurović, S.; Jovanović, M.

    2016-09-01

    Context. We present the largest catalog of detailed stellar kinematics of the central parts of nearby galaxies, which includes higher moments of the line-of-sight velocity distribution (LOSVD) function represented by the Gauss-Hermite series. The kinematics is measured on a sample of galaxies selected from the Arecibo Legacy Fast ALFA (Alfalfa) survey using spectroscopy from the Sloan Digital Sky Survey (SDSS DR7). Aims: The SDSS DR7 offers measurements of the LOSVD based on the assumption of a pure Gaussian shape of the broadening function caused by the combination of rotational and random motion of the stars in galaxies. We discuss the consequences of this oversimplification since the velocity dispersion, one of the measured quantities, often serves as the proxy to important modeling parameters such as the black-hole mass and the virial mass of galaxies. Methods: The publicly available pPXF code is used to calculate the full kinematical profile for the sample galaxies including higher moments of their LOSVD. Both observed and synthetic stellar libraries were used and the related template mismatch problem is discussed. Results: For the whole sample of 2180 nearby galaxies reflecting morphological distribution characteristic for the local Universe, we successfully recovered stellar kinematics of their central parts, including higher order moments of the LOSVD function, for signal-to-noise above 50. Conclusions: We show the consequences of the oversimplification of the LOSVD function with Gaussian function on the velocity dispersion for the empirical and the synthetic stellar library. For the empirical stellar library, this approximation leads to an increase in the virial mass of 13% on average, while for the synthetic library the effect is weaker, with an increase of 9% on average. Systematic erroneous estimates of the velocity dispersion comes from the use of the synthetic stellar library instead of the empirical one and is much larger than the value imposed by

  2. The environment of nearby Blue Compact Dwarf Galaxies

    CERN Document Server

    Lopez-Sanchez, Angel R; van Eymeren, Janine; Esteban, Cesar; Popping, Attila; Hibbard, John

    2009-01-01

    We are obtaining deep multiwavelength data of a sample of nearby blue compact dwarf galaxies (BCDGs) combining broad-band optical/NIR and H$\\alpha$ photometry, optical spectroscopy and 21-cm radio observations. Here we present HI results obtained with the Australia Telescope Compact Array for some BCDGs, all showing evident interaction features in their neutral gas component despite the environment in which they reside. Our analysis strongly suggests that interactions with or between low-luminosity dwarf galaxies or HI clouds are the main trigger mechanism of the star-forming bursts in BCDGs; however these dwarf objects are only detected when deep optical images and complementary HI observations are performed. Are therefore BCDGs real isolated systems?

  3. Mid-J CO Emission in Nearby Seyfert Galaxies

    CERN Document Server

    Pereira-Santaella, M; Busquet, G; Glenn, J; Isaak, K; Kamenetzky, J; Rangwala, N; Schirm, M R P; Baes, M; Barlow, M J; Boselli, A; Cooray, A; Cormier, D

    2013-01-01

    We study for the first time the complete sub-millimeter spectra (450 GHz to 1550 GHz) of a sample of nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) onboard Herschel. The CO ladder (from Jup = 4 to 12) is the most prominent spectral feature in this range. These CO lines probe warm molecular gas that can be heated by ultraviolet photons, shocks, or X-rays originated in the active galactic nucleus or in young star-forming regions. In these proceedings we investigate the physical origin of the CO emission using the averaged CO spectral line energy distribution (SLED) of six Seyfert galaxies. We use a radiative transfer model assuming an isothermal homogeneous medium to estimate the molecular gas conditions. We also compare this CO SLED with the predictions of photon and X-ray dominated region (PDR and XDR) models.

  4. The Red and Featureless Outer Disks of Nearby Spiral Galaxies

    Science.gov (United States)

    Watkins, Aaron E.; Mihos, J. Christopher; Harding, Paul

    2016-07-01

    We present results from deep, wide-field surface photometry of three nearby (D = 4-7 Mpc) spiral galaxies: M94 (NGC 4736), M64 (NGC 4826), and M106 (NGC 4258). Our imaging reaches a limiting surface brightness of {μ }B ˜ 28-30 mag arcsec-2 and probes colors down to {μ }B ˜ 27.5 mag arcsec-2. We compare our broadband optical data to available ultraviolet and high column density H i data to better constrain the star-forming history and stellar populations of the outermost parts of each galaxy’s disk. Each galaxy has a well-defined radius beyond which little star formation occurs and the disk light appears both azimuthally smooth and red in color, suggestive of old, well-mixed stellar populations. Given the lack of ongoing star formation or blue stellar populations in these galaxies’ outer disks, the most likely mechanisms for their formation are dynamical processes such as disk heating or radial migration, rather than inside-out growth of the disks. This is also implied by the similarity in outer disk properties despite each galaxy showing distinct levels of environmental influence, from a purely isolated galaxy (M94) to one experiencing weak tidal perturbations from its satellite galaxies (M106) to a galaxy recovering from a recent merger (M64), suggesting that a variety of evolutionary histories can yield similar outer disk structure. While this suggests a common secular mechanism for outer disk formation, the large extent of these smooth, red stellar populations—which reach several disk scale lengths beyond the galaxies’ spiral structure—may challenge models of radial migration given the lack of any nonaxisymmetric forcing at such large radii.

  5. The Red and Featureless Outer Disks of Nearby Spiral Galaxies

    CERN Document Server

    Watkins, Aaron E; Harding, Paul

    2016-01-01

    We present results from deep, wide-field surface photometry of three nearby (D=4--7 Mpc) spiral galaxies: M94 (NGC 4736), M64 (NGC 4826), and M106 (NGC 4258). Our imaging reaches limiting surface brightnesses of $\\mu_{B} \\sim$ 28 -- 30 mag arcsec$^{-2}$ and probes colors down to $\\mu_{B} \\sim$ 27.5 mag arcsec$^{-2}$. We compare our broadband optical data to available ultraviolet and high column-density HI data to better constrain the star forming history and stellar populations of the outermost parts of each galaxy's disk. Each galaxy has a well-defined radius beyond which little star formation occurs and the disk light appears both azimuthally smooth and red in color, suggestive of old, well-mixed stellar populations. Given the lack of ongoing star formation or blue stellar populations in these galaxies' outer disks, the most likely mechanisms for their formation are dynamical processes such as disk heating or radial migration, rather than inside-out growth of the disks. This is also implied by the similarit...

  6. The Nuclear Near-Infrared Spectral Properties of Nearby Galaxies

    CERN Document Server

    Mason, R E; Martins, L; Riffel, R; Martin, O Gonzalez; Almeida, C Ramos; Dutra, D Ruschel; Ho, L C; Thanjavur, K; Flohic, H; Alonso-Herrero, A; Lira, P; McDermid, R; Riffel, R A; Schiavon, R P; Winge, C; Hoenig, M D; Perlman, E

    2015-01-01

    We present spectra of the nuclear regions of 50 nearby (D = 1 - 92 Mpc, median = 20 Mpc) galaxies of morphological types E to Sm. The spectra, obtained with the Gemini Near-IR Spectrograph on the Gemini North telescope, cover a wavelength range of approximately 0.85-2.5 microns at R~1300--1800. There is evidence that most of the galaxies host an active galactic nucleus (AGN), but the range of AGN luminosities (log (L2-10 keV [erg/s]) = 37.0-43.2) in the sample means that the spectra display a wide variety of features. Some nuclei, especially the Seyferts, exhibit a rich emission-line spectrum. Other objects, in particular the type 2 Low Ionisation Nuclear Emission Region galaxies, show just a few, weak emission lines, allowing a detailed view of the underlying stellar population. These spectra display numerous absorption features sensitive to the stellar initial mass function, as well as molecular bands arising in cool stars, and many other atomic absorption lines. We compare the spectra of subsets of galaxie...

  7. Lyman Alpha Emitting Galaxies in the Nearby Universe

    Science.gov (United States)

    Hayes, Matthew

    2015-07-01

    The Lyman alpha emission line (Lyα) of neutral hydrogen (Hi) is intrinsically the brightest emission feature in the spectrum of astrophysical nebulae, making it a very attractive observational feature with which to survey galaxies. Moreover as an ultraviolet resonance line, Lyα possesses several unique characteristics that make it useful to study the properties of the interstellar medium and ionising stellar population at all cosmic epochs. In this review, I present a summary of Lyα observations of galaxies in the nearby universe. By ultraviolet continuum selection, at the magnitudes reachable with current facilities, only ≈ 5% of the local galaxy population shows a Lyα equivalent width (W Lyα) that exceeds 20 Å. This fraction increases dramatically at higher redshifts, but only in the local universe can we study galaxies in detail and assemble unprecedented multi-wavelength datasets. I discuss many local Lyα observations, showing that when galaxies show net Lyα emission, they ubiquitously also produce large-scale halos of scattered Lyα, that dominate the integrated luminosity. Concerning global measurements, we discuss how W Lyα and the Lyα escape fraction (f Lyα esc) are higher (W Lyα ≳ 20 Å and f Lyα esc ≳ 10%) in galaxies that represent the less massive and younger end of the distribution for local objects. This is connected with various properties, such that Lyα-emitting galaxies have lower metal abundances (median value of 12 + log(O/H) ~ 8.1) and dust reddening. However, the presence of galactic outflows/winds is also vital to Doppler shift the Lyα line out of resonance with the atomic gas, and high W Lyα is found only among galaxies with winds faster than ~ 50 km s-1. The empirical evidence is then assembled into a coherent picture, and the requirement for star-formation-driven feedback is discussed in the context of an evolutionary sequence where the interstellar medium is accelerated and/or subject to hydrodynamical instabilities

  8. The Dragonfly Nearby Galaxies Survey. I. Substantial variation in the diffuse stellar halos around spiral galaxies

    CERN Document Server

    Merritt, Allison; Abraham, Roberto; Zhang, Jielai

    2016-01-01

    Galaxies are thought to grow through accretion; as less massive galaxies are disrupted and merge over time, their debris results in diffuse, clumpy stellar halos enveloping the central galaxy. Here we present a study of the variation in the stellar halos of galaxies, using data from the Dragonfly Nearby Galaxies Survey (DNGS). The survey consists of wide field, deep ($\\mu_{g} > 31$ mag arcsec$^{-2}$) optical imaging of nearby galaxies using the Dragonfly Telephoto Array. Our sample includes eight spiral galaxies with stellar masses similar to that of the Milky Way, inclinations of $16-90$ degrees and distances between $7-18$ Mpc. We construct stellar mass surface density profiles from the observed $g$-band surface brightness in combination with the $g-r$ color as a function of radius, and compute the halo fractions from the excess stellar mass (relative to a disk$+$bulge fit) beyond $5$ half-mass radii. We find a mean halo fraction of $0.009 \\pm 0.005$ and a large RMS scatter of $1.01^{+0.9}_{-0.26}$ dex. The...

  9. Dark matter searches with Cherenkov telescopes: nearby dwarf galaxies or local galaxy clusters?

    CERN Document Server

    Sanchez-Conde, Miguel A; Zandanel, F; Gomez, Mario E; Prada, F

    2011-01-01

    In the last few years, most of the attention in gamma-ray dark matter (DM) searches has been devoted to neutralino annihilations in nearby dwarf galaxies. However, massive galaxy clusters in the local Universe may constitute very good targets as well. The main aim of this work is to compare both dwarf galaxies and local galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies and galaxy clusters, and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman~1 appears as the best candidate in the sample and, given the morphology of its annihilation signal, it is also one of the objects more readily observable by IACTs. As for galaxy clusters, Virgo represents the one with the hi...

  10. MAPPING DUST THROUGH EMISSION AND ABSORPTION IN NEARBY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Kreckel, Kathryn; Groves, Brent; Schinnerer, Eva; Meidt, Sharon E.; Tabatabaei, Fatemeh S. [Max Planck Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Johnson, Benjamin D. [Institut d' Astrophysique de Paris, UMR 7095, 98 bis Bvd Arago, F-75014 Paris (France); Aniano, Gonzalo [Institut d' Astrophysique Spatiale (IAS), Batiment 121, Universite Paris-Sud 11 and CNRS (UMR 8617), F-91405 Orsay (France); Calzetti, Daniela [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Croxall, Kevin V. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Draine, Bruce T. [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001 (United States); Gordon, Karl D. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Crocker, Alison F.; Smith, J. D. T. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Dale, Daniel A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Hunt, Leslie K. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Kennicutt, Robert C., E-mail: kreckel@mpia.de [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2013-07-01

    Dust has long been identified as a barrier to measuring inherent galaxy properties. However, the link between dust and attenuation is not straightforward and depends on both the amount of dust and its distribution. Herschel imaging of nearby galaxies undertaken as part of the KINGFISH project allows us to map the dust as seen in emission with unprecedented sensitivity and {approx}1 kpc resolution. We present here new optical integral field unit spectroscopy for eight of these galaxies that provides complementary 100-200 pc scale maps of the dust attenuation through observation of the reddening in both the Balmer decrement and the stellar continuum. The stellar continuum reddening, which is systematically less than that observed in the Balmer decrement, shows no clear correlation with the dust, suggesting that the distribution of stellar reddening acts as a poor tracer of the overall dust content. The brightest H II regions are observed to be preferentially located in dusty regions, and we do find a correlation between the Balmer line reddening and the dust mass surface density for which we provide an empirical relation. Some of the high-inclination systems in our sample exhibit high extinction, but we also find evidence that unresolved variations in the dust distribution on scales smaller than 500 pc may contribute to the scatter in this relation. We caution against the use of integrated A{sub V} measures to infer global dust properties.

  11. Molecular Gas and Star Formation in Nearby Disk Galaxies

    CERN Document Server

    Leroy, Adam K; Sandstrom, Karin; Schruba, Andreas; Munoz-Mateos, Juan-Carlos; Bigiel, Frank; Bolatto, Alberto; Brinks, Elias; de Blok, W J G; Meidt, Sharon; Rix, Hans-Walter; Rosolowsky, Erik; Schinnerer, Eva; Schuster, Karl-Friedrich; Usero, Antonio

    2013-01-01

    We compare molecular gas traced by 12CO(2-1) maps from the HERACLES survey, with tracers of the recent star formation rate (SFR) across 30 nearby disk galaxies. We demonstrate a first-order linear correspondence between Sig_mol and Sig_SFR but also find important second-order systematic variations in the apparent molecular gas depletion time, t_dep^mol = Sig_mol / Sig_SFR. At our 1 kpc common resolution, CO correlates closely with many tracers of the recent SFR. Weighting each line of sight equally and using a fixed, Milky Way alpha_CO, our data yield a molecular gas depletion time, t_dep^mol=Sig_mol/Sig_SFR ~ 2.2 Gyr with 0.3 dex scatter, in good agreement with literature data. We apply a forward-modeling approach to constrain the power-law index, N, that relates the SFR surface density and the molecular gas surface density and find N=1+/-0.15 for our full data set with some variation from galaxy to galaxy. However, we caution that a power law treatment oversimplifies the topic given that we observe correlat...

  12. The Carnegie-Irvine Galaxy Survey. III. The Three-Component Structure of Nearby Elliptical Galaxies

    CERN Document Server

    Huang, Song; Peng, Chien Y; Li, Zhao-Yu; Barth, Aaron J

    2012-01-01

    Motivated by recent developments in our understanding of the formation and evolution of massive galaxies, we explore the detailed photometric structure of a representative sample of 94 bright, nearby elliptical galaxies, using high-quality optical images from the Carnegie-Irvine Galaxy Survey. The sample spans a range of environments and stellar masses, from M* = 10^{10.2} to 10^{12.0} solar mass. We exploit the unique capabilities of two-dimensional image decomposition to explore the possibility that local elliptical galaxies may contain photometrically distinct substructure that can shed light on their evolutionary history. Compared with the traditional one-dimensional approach, these two-dimensional models are capable of consistently recovering the surface brightness distribution and the systematic radial variation of geometric information at the same time. Contrary to conventional perception, we find that the global light distribution of the majority (>75%) of elliptical galaxies is not well described by ...

  13. Faint Galaxies in deep ACS observations

    CERN Document Server

    Benítez, N; Bouwens, R; Menanteau, F; Blakeslee, J P; Gronwall, C; Illingworth, G D; Meurer, G; Broadhurst, T J; Clampin, M; Franx, M; Hartig, G F; Magee, D; Sirianni, M; Ardila, D R; Bartko, F; Brown, R A; Burrows, C J; Cheng, E S; Cross, N J G; Feldman, P D; Golimowski, D A; Infante, L; Kimble, R A; Krist, J E; Lesser, M P; Levay, Z G; Martel, A R; Miley, G K; Postman, M; Rosati, P; Sparks, W B; Tran, H D; Tsvetanov, Z I; Zheng, R L

    2003-01-01

    We present the analysis of the faint galaxy population in the Advanced Camera for Surveys (ACS) Early Release Observation fields VV 29 (UGC 10214) and NGC 4676. Here we attempt to thoroughly consider all aspects relevant for faint galaxy counting and photometry, developing methods which are based on public software and that are easily reproducible by other astronomers. Using simulations we determine the best SExtractor parameters for the detection of faint galaxies in deep HST observations, paying special attention to the issue of deblending, which significantly affects the normalization and shape of the number count distribution. We confirm, as claimed by Bernstein, Freedman and Madore (2002), that Kron-like magnitudes, such as the ones generated by SExtractor, can miss more than half of the light of faint galaxies, what dramatically affects the slope of the number counts. We present catalogs for the VV 29 and NGC 4676 fields with photometry in the g,V and I bands. We also show that combining the bayesian so...

  14. Mass-Models of Five Nearby Dwarf Irregular Galaxies

    CERN Document Server

    Côté, S; Carignan, C; Cote, Stephanie; Freeman, Ken; Carignan, Claude

    1997-01-01

    Five nearby dwarf irregular galaxies, amongst the recently surveyed dwarf members of the Sculptor and Centaurus A groups (at 2.5 Mpc and 3.5 Mpc), have been imaged in neutral hydrogen (HI) with the Australia Telescope and the Very Large Array. These objects have absolute magnitudes M_B in the range -14.9 to -12.7, yet they are clearly rotationally supported, with maximum rotation velocities ranging from 43 km/s to 67 km/s. Multi-component mass-models have been fitted to the rotation curves. We investigate the properties of their dark matter halos, and the scaling laws of the dark matter halos parameters.

  15. The Dragonfly nearby Galaxies Survey. I. Substantial Variation in the Diffuse Stellar Halos around Spiral Galaxies

    Science.gov (United States)

    Merritt, Allison; van Dokkum, Pieter; Abraham, Roberto; Zhang, Jielai

    2016-10-01

    Galaxies are thought to grow through accretion; as less massive galaxies are disrupted and merge over time, their debris results in diffuse, clumpy stellar halos enveloping the central galaxy. Here we present a study of the variation in the stellar halos of galaxies, using data from the Dragonfly Nearby Galaxies Survey (DNGS). The survey consists of wide field, deep ({μ }g\\gt 31 mag arcsec‑2) optical imaging of nearby galaxies using the Dragonfly Telephoto Array. Our sample includes eight spiral galaxies with stellar masses similar to that of the Milky Way, inclinations of 16-19 degrees and distances between 7-18 Mpc. We construct stellar mass surface density profiles from the observed g-band surface brightness in combination with the g ‑ r color as a function of radius, and compute the halo fractions from the excess stellar mass (relative to a disk+bulge fit) beyond 5 half-mass radii. We find a mean halo fraction of 0.009 ± 0.005 and a large rms scatter of {1.01}-0.26+0.9 dex. The peak-to-peak scatter of the halo fraction is a factor of \\gt 100—while some galaxies feature strongly structured halos resembling that of M31, three of the eight have halos that are completely undetected in our data. We conclude that spiral galaxies as a class exhibit a rich variety in stellar halo properties, implying that their assembly histories have been highly non-uniform. We find no convincing evidence for an environmental or stellar mass dependence of the halo fraction in the sample.

  16. Observations of Cold Dust in Nearby Elliptical Galaxies

    Science.gov (United States)

    Leeuw, Lerothodi L.; Sansom, Anne E.; Robson, E. Ian; Haas, Martin; Kuno, Nario

    2004-09-01

    Spectral energy distribution (SED) analyses that include new millimeter to far-infrared (FIR) observations obtained with continuum instruments on the Nobeyama and James Clerk Maxwell Telescopes and the Infrared Space Observatory are presented for seven nearby (shortwave radio data obtained from the NASA/IPAC Extragalactic Database (NED). The radio to infrared SEDs are best-fitted by power law plus graybody models of dust residing in the central galactic regions within a 2.4 kpc diameter and with temperatures between ~21 and 28 K, emissivity index ~=2, and masses from ~1.6 to 19×105Msolar. The emissivity index is consistent with dust constituting amorphous silicate and carbonaceous grains previously modeled for stellar-heated dust observed in the Galaxy and other nearby extragalactic sources. Using updated dust absorption coefficients for this type of dust, dust masses are estimated that are similar to those determined from earlier FIR data alone, even though the latter results implied hotter dust temperatures. Fluxes and masses that are consistent with the new FIR and submillimeter data are estimated for dust cooler than 20 K within the central galactic regions. Tighter physical constraints for such cold, diffuse dust (if it exists) with low surface brightness will need sensitive FIR to submillimeter observations with the Spitzer Space Telescope, SCUBA2, or ALMA.

  17. Resolved Near-Infrared Stellar Populations in Nearby Galaxies

    CERN Document Server

    Dalcanton, Julianne J; Melbourne, Jason L; Girardi, Léo; Dolphin, Andy; Rosenfield, Philip A; Boyer, Martha L; de Jong, Roelof S; Gilbert, Karoline; Marigo, Paola; Olsen, Knut; Seth, Anil C; Skillman, Evan

    2011-01-01

    We present near-infrared (NIR) color-magnitude diagrams (CMDs) for the resolved stellar populations within 26 fields of 23 nearby galaxies (<4 Mpc), based on F110W and F160W images from Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). The CMDs sample both old dormant and young star-forming populations. We match key NIR CMD features with their counterparts in optical CMDs, and identify the red core Helium burning (RHeB) sequence as a significant contributor to the NIR flux in stellar populations younger than a few 100 Myrs old, suggesting that star formation can drive surprisingly rapid variations in the NIR mass-to-light ratio. The NIR luminosity of star forming galaxies is therefore not necessarily proportional to the stellar mass. We note that these individual bright RHeB stars may be misidentified as old stellar clusters in low resolution imaging. We also discuss the CMD location of asymptotic giant branch (AGB) stars, and the separation of AGB sub-populations using a combination of optic...

  18. The Mitchell Spectrograph: Studying Nearby Galaxies with the VIRUS Prototype

    CERN Document Server

    Blanc, Guillermo A

    2014-01-01

    The Mitchell Spectrograph (a.k.a. VIRUS-P) on the 2.7m Harlan J. Smith telescope at McDonald Observatory is currently the largest field of view (FOV) integral field unit (IFU) spectrograph in the world (1.7'x1.7'). It was designed as a prototype for the highly replicable VIRUS spectrograph which consists of a mosaic of IFUs spread over a 16' diameter FOV feeding 150 spectrographs similar to the Mitchell. VIRUS will be deployed on the 9.2 meter Hobby-Eberly Telescope (HET) and will be used to conduct the HET Dark Energy Experiment (HETDEX). Since seeing first light in 2007 the Mitchell Spectrograph has been widely used, among other things, to study nearby galaxies in the local universe where their internal structure and the spatial distribution of different physical parameters can be studied in great detail. These observations have provided important insight into many aspects of the physics behind the formation and evolution of galaxies and have boosted the scientific impact of the 2.7 meter telescope enormous...

  19. Chandra Examines Black Holes Large and Small in Nearby Galaxy

    Science.gov (United States)

    2001-05-01

    Probing a large, nearby galaxy in the constellation of Circinus, NASA’s Chandra X-ray Observatory presents a new view of both the galaxy’s supermassive black hole and a host of potential smaller black holes sprinkled throughout its spiral arms. The results include the first detection of a black hole’s periodic variability in X-rays outside our galactic neighborhood. Astronomers from Penn State University used Chandra to discover a variable object within the dozen or so X-ray emitting sources sprinkled throughout the Circinus galaxy. The intensity of X-rays from this source changes on a cycle of 7.5 hours - the first time this "periodic variability" has been detected at X-ray wavelengths in an object outside the "Local Group" of galaxies. And, along with its brightness, this evidence strongly suggests that the system contains a black hole some 50 times the mass of the Sun. "Extremely luminous X-ray sources such as this one appear to be common among other galaxies," said Franz Bauer, a postdoctoral scholar at Penn State and lead author of a July 2001 paper in The Astronomical Journal. "But until Chandra, we have never had an instrument that could clearly identify whether they were simply massive X-ray binary systems, or if they represented a new class of objects" "The periodic variability in the Chandra data of Circinus provides us with a key signature that these objects are indeed X-ray binary systems," continued Bauer. "This is important because black holes with masses much larger than 10 times the mass of the Sun such as this one are difficult to explain under current theories of star formation and destruction. Definitively finding a periodic signal in one allows us to test some of our past assumptions." The X-ray data acquired by two independent teams -- one at Penn State and George Mason University and the other at the University of Maryland -- also provide evidence that strongly supports the "unified model," a theory in which a large doughnut-shaped ring

  20. The Chemical Anatomy of Nuclei of Nearby Barred Spiral Galaxies

    Science.gov (United States)

    Meier, D. S.; Turner, J. L.

    2004-12-01

    We present images of the millimeter lines of eight molecules---C2H, C34S, N2H+, CH3OH, HNCO, HNC, HC3N, and SO---in the nuclei of the nearby barred spiral galaxies, IC 342 and Maffei 2, made with the OVRO and BIMA arrays. These maps are compared to obtain a picture of changes in chemistry on sizescales of individual giant molecular clouds (GMCs) within a nucleus and between nuclei of similar morphological type. Emission from all species except SO are detected in both galaxies. Marked differences in morphology between the observed species are seen in both galaxies. A principal component analysis (PCA) is performed to quantify differences among the images. In IC 342, the PCA reveals that while all molecules are zeroth order correlated, that is, trace dense GMCs, there are three distinct groups of molecules distinguished by the location of their emission within the nucleus. N2H+ and HNC are widespread and bright, tracing all of the GMCs. C2H and C34S, tracers of photo-dissociation region chemistry, originate exclusively from the central ˜ 5'' ring illuminated by the 60 Myr, massive central cluster. CH3OH (and HNCO), a typical tracer of grain processing, correlates well with the expected locations of bar-induced orbital shocks. In Maffei 2, the PCA demonstrates that its chemistry is quite similar to IC 342, with the molecules tending to couple together in the same groups and with the same structural components of the nucleus. C2H dominates from the central starburst region, but is significantly more extended than IC 342 because its star formation is more extended. The correlation between HNCO and CH3OH in Maffei 2 is even strongly than in IC 342, being entirely dominated by the bar ends and orbit intersections. This provides strong evidence that HNCO is formed by the same processes as CH3OH. Funding for this research is provided by the Laboratory for Astronomical Imaging at the University of Illinois through the NSF grant AST-0228953, and by NSF grants AST-0071276 and

  1. A Supermassive Black Hole in a Nearby Galaxy

    Science.gov (United States)

    2001-03-01

    ISAAC Inspects the Center of Centaurus A Summary The nearby galaxy Centaurus A harbours a supermassive black hole at its centre . Using the ISAAC instrument at the ESO Very Large Telescope (VLT) , an international team of astronomers [1] has peered right through the spectacular dust lane of the peculiar galaxy Centaurus A , located approximately 11 million light-years away. They were able to probe the thin disk of gas that surrounds the very center of this galaxy. The new measurements show that the compact nucleus in the middle weighs more than 200 million solar masses ! This is too much just to be due to normal stars. The astronomers thus conclude the existence of a supermassive black hole lurking at the centre of Centaurus A . PR Photo 08a/01 : Visual image of the centre of Centaurus A . PR Photo 08b/01 : ISAAC spectrum of the centre of Centaurus A . PR Photo 08c/01 : The corresponding rotation curve from which the mass of the black hole was deduced. A well studied galaxy with a hidden center ESO PR Photo 08a/01 ESO PR Photo 08a/01 [Preview - JPEG: 352 x 400 pix - 160k] [Normal - JPEG: 704 x 800 pix - 376k] Caption : PR Photo 08a/01 shows a small area in the direction of the heavily obscured centre of the peculiar radio galaxy Centaurus A , as seen in visual light. It measures about 80 x 80 arcsec 2 , or 4400 x 4400 light-year 2 at the distance of this galaxy, and has been reproduced from exposures made with the FORS2 multi-mode instrument at the 8.2-m VLT KUEYEN telescope at Paranal. The full field may be seen in PR Photo 05b/00. Technical information about this photo is available below. The galaxy Centaurus A (NGC 5128) is one of the most studied objects in the southern sky. The unique appearance of this galaxy was already noticed by the famous British astronomer John Herschel in 1847 who catalogued the southern skies and made a comprehensive list of "nebulae". A fine photo of Centaurus A from the VLT was published last year as PR Photo 05b/00. Herschel could

  2. The Observational Mass Function of Nearby Galaxy Clusters

    CERN Document Server

    Girardi, M; Giuricin, G; Mardirossian, F; Mezzetti, M

    1998-01-01

    We present a new determination of the mass function of galaxy clusters, based on optical virial mass estimates for a large sample of 152 nearby (z M_lim)=(6.3\\pm 1.2) 10^{-6} (h^{-1} Mpc)^{-3} for cluster masses estimated within a 1.5 h^{-1} Mpc radius. Our mass function is intermediate between the two previous estimates by Bahcall & Cen (1993) and by Biviano et al. (1993). Based on the Press--Schechter approach, we use this mass function to constrain the amplitude of the fluctuation power spectrum at the cluster scale. After suitably convolving the PS predictions with observational errors on cluster masses and COBE--normalizing the fluctuation power spectrum, we find sigma_8=(0.60\\pm 0.04) Omega_0^{-0.46+0.09Omega_0} for flat low--density models and \\sigma_8=(0.60\\pm 0.04) Omega_0^{-0.48+0.17Omega_0} for open models (at the 90% c.l.).

  3. HUBBLE PEEKS INTO A STELLAR NURSERY IN A NEARBY GALAXY

    Science.gov (United States)

    2002-01-01

    HUBBLE PEEKS INTO A STELLAR NURSERY IN A NEARBY GALAXY NASA's Hubble Space Telescope has peered deep into a neighboring galaxy to reveal details of the formation of new stars. Hubble's target was a newborn star cluster within the Small Magellanic Cloud, a small galaxy that is a satellite of our own Milky Way. The new images show young, brilliant stars cradled within a nebula, or glowing cloud of gas, cataloged as N 81. These massive, recently formed stars inside N 81 are losing material at a high rate, sending out strong stellar winds and shock waves and hollowing out a cocoon within the surrounding nebula. The two most luminous stars, seen in the Hubble image as a very close pair near the center of N 81, emit copious ultraviolet radiation, causing the nebula to glow through fluorescence. Outside the hot, glowing gas is cooler material consisting of hydrogen molecules and dust. Normally this material is invisible, but some of it can be seen in silhouette against the nebular background, as long dust lanes and a small, dark, elliptical-shaped knot. It is believed that the young stars have formed from this cold matter through gravitational contraction. Few features can be seen in N 81 from ground-based telescopes, earning it the informal nick-name 'The Blob.' Astronomers were not sure if just one or a few hot stars were embedded in the cloud, or if it was a stellar nursery containing a large number of less massive stars. Hubble's high-resolution imaging shows the latter to be the case, revealing that numerous young, white-hot stars---easily visible in the color picture---are contained within N 81. This crucial information bears strongly on theories of star formation, and N 81 offers a singular opportunity for a close-up look at the turbulent conditions accompanying the birth of massive stars. The brightest stars in the cluster have a luminosity equal to 300,000 stars like our own Sun. Astronomers are especially keen to study star formation in the Small Magellanic

  4. MOLECULAR GAS AND STAR FORMATION IN NEARBY DISK GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, Adam K.; Munoz-Mateos, Juan-Carlos [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Walter, Fabian; Sandstrom, Karin; Meidt, Sharon; Rix, Hans-Walter; Schinnerer, Eva [Max Planck Institute fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Schruba, Andreas [California Institute for Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Bigiel, Frank [Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Bolatto, Alberto [Department of Astronomy, University of Maryland, College Park, MD (United States); Brinks, Elias [Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); De Blok, W. J. G. [Astrophysics, Cosmology and Gravity Centre, Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa); Rosolowsky, Erik [University of British Columbia, Okanagan Campus, Kelowna, BC (Canada); Schuster, Karl-Friedrich [IRAM, 300 rue de la Piscine, F-38406 St. Martin d' Heres (France); Usero, Antonio [Observatorio Astronomico Nacional, C/ Alfonso XII, 3, E-28014 Madrid (Spain)

    2013-08-01

    We compare molecular gas traced by {sup 12}CO (2-1) maps from the HERACLES survey, with tracers of the recent star formation rate (SFR) across 30 nearby disk galaxies. We demonstrate a first-order linear correspondence between {Sigma}{sub mol} and {Sigma}{sub SFR} but also find important second-order systematic variations in the apparent molecular gas depletion time, {tau}{sub dep}{sup mol}={Sigma}{sub mol}/{Sigma}{sub SFR}. At the 1 kpc common resolution of HERACLES, CO emission correlates closely with many tracers of the recent SFR. Weighting each line of sight equally, using a fixed {alpha}{sub CO} equivalent to the Milky Way value, our data yield a molecular gas depletion time, {tau}{sub dep}{sup mol}={Sigma}{sub mol}/{Sigma}{sub SFR}{approx}2.2 Gyr with 0.3 dex 1{sigma} scatter, in very good agreement with recent literature data. We apply a forward-modeling approach to constrain the power-law index, N, that relates the SFR surface density and the molecular gas surface density, {Sigma}{sub SFR}{proportional_to}{Sigma}{sub mol}{sup N}. We find N = 1 {+-} 0.15 for our full data set with some scatter from galaxy to galaxy. This also agrees with recent work, but we caution that a power-law treatment oversimplifies the topic given that we observe correlations between {tau}{sub dep}{sup mol} and other local and global quantities. The strongest of these are a decreased {tau}{sub dep}{sup mol} in low-mass, low-metallicity galaxies and a correlation of the kpc-scale {tau}{sub dep}{sup mol} with dust-to-gas ratio, D/G. These correlations can be explained by a CO-to-H{sub 2} conversion factor ({alpha}{sub CO}) that depends on dust shielding, and thus D/G, in the theoretically expected way. This is not a unique interpretation, but external evidence of conversion factor variations makes this the most conservative explanation of the strongest observed {tau}{sub dep}{sup mol} trends. After applying a D/G-dependent {alpha}{sub CO}, some weak correlations between {tau}{sub dep

  5. The JCMT Nearby Galaxies Legacy Survey II: Warm Molecular Gas and Star Formation in Three Field Spiral Galaxies

    CERN Document Server

    Warren, B E; Israel, F P; Serjeant, S; Bendo, G J; Brinks, E; Clements, D L; Irwin, J A; Knapen, J H; Leech, J; Matthews, H E; Mühle, S; Mortimer, A M J; Petitpas, G; Sinukoff, E; Spekkens, K; Tan, B K; Tilanus, R P J; Usero, A; van der Werf, P P; Vlahakis, C; Wiegert, T; Zhu, M

    2010-01-01

    We present the results of large-area CO J=3-2 emission mapping of three nearby field galaxies, NGC 628, NGC 3521, and NGC 3627, completed at the James Clerk Maxwell Telescope as part of the Nearby Galaxies Legacy Survey. These galaxies all have moderate to strong CO J=3-2 detections over large areas of the fields observed by the survey, showing resolved structure and dynamics in their warm/dense molecular gas disks. All three galaxies were part of the Spitzer Infrared Nearby Galaxies Survey sample, and as such have excellent published multi-wavelength ancillary data. These data sets allow us to examine the star formation properties, gas content, and dynamics of these galaxies on sub-kiloparsec scales. We find that the global gas depletion times for dense/warm molecular gas in these galaxies is consistent with other results for nearby spiral galaxies, indicating this may be independent of galaxy properties such as structures, gas compositions, and environments. Similar to the results from the THINGS HI survey,...

  6. Extending the Nearby Galaxy Heritage with WISE: First Results from the WISE Enhanced Resolution Galaxy Atlas

    CERN Document Server

    Jarrett, T H; Tsai, C W; Petty, S; Cluver, M; Assef, Roberto J; Benford, D; Blain, A; Bridge, C; Donoso, E; Eisenhardt, P; Koribalski, B; Lake, S; Neill, James D; Seibert, M; Sheth, K; Stanford, S; Wright, E

    2012-01-01

    The Wide-field Infrared Survey Explorer (WISE) mapped the entire sky at mid-infrared wavelengths 3.4, 4.6, 12 and 22 microns. The mission was primarily designed to extract point sources, leaving resolved and extended sources unexplored. We have begun a dedicated WISE Enhanced Resolution Galaxy Atlas (WERGA) project to fully characterize large, nearby galaxies and produce a legacy image atlas and source catalogue. Here we demonstrate the first results of the project for a sample of 17 galaxies, chosen to be of large angular size, diverse morphology, color, stellar mass and star formation. It includes many well-studied galaxies, such as M51, M81, M83, M87, M101, IC342. Photometry and surface brightness decomposition is carried out after special super-resolution processing, achieving spatial fidelity similar to that of Spitzer-IRAC. We present WISE, Spitzer and GALEX photometric and characterization measurements, combining the measurements to study the global properties. We derive star formation rates using the ...

  7. Mapping Nearby Galaxies at APO: The MaNGA IFU Galaxy Survey

    Science.gov (United States)

    Law, David R.; MaNGA Team

    2014-01-01

    MaNGA is a new survey that will begin in August 2014 as part of SDSS-IV with the aim of obtaining integral-field spectroscopy for an unprecedented sample of 10,000 nearby galaxies. MaNGA's key goals are to understand the "life cycle" of present day galaxies from imprinted clues of their birth and assembly, through their ongoing growth via star formation and merging, to their death from quenching at late times. To achieve these goals, MaNGA will channel the impressive capabilities of the SDSS-III BOSS spectrographs in a fundamentally new direction by marshaling the unique power of 2D spectroscopy. MaNGA will deploy 17 pluggable Integral Field Units (IFUs) made by grouping fibers into hexagonal bundles ranging from 19 to 127 fibers each. The spectra obtained by MaNGA will cover the wavelength range 3600-10,000 Angstroms (with a velocity resolution of ~ 60 km/s) and will characterize the internal composition and the dynamical state of a sample of 10,000 galaxies with stellar masses greater than 10^9 Msun and an average redshift of z ~ 0.03. Such IFU observations enable a leap forward because they provide an added dimension to the information available for each galaxy. MaNGA will provide two-dimensional maps of stellar velocity and velocity dispersion, mean stellar age and star formation history, stellar metallicity, element abundance ratio, stellar mass surface density, ionized gas velocity, ionized gas metallicity, star formation rate, and dust extinction for a statistically powerful sample. This legacy dataset will address urgent questions in our understanding of galaxy formation, including 1) The formation history of galaxy subcomponents, including the disk, bulge, and dark matter halo, 2) The nature of present-day galaxy growth via merging and gas accretion, and 3) The processes responsible for terminating star formation in galaxies. Finally, MaNGA will also play a vital role in the coming era of advanced IFU instrumentation, serving as the low-z anchor for

  8. Dark Matter Searches with Cherenkov Telescopes: Nearby Dwarf Galaxies or Local Galaxy Clusters?

    International Nuclear Information System (INIS)

    In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC 5813 and NGC 5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for present and future IACTs in the framework of the constrained minimal supersymmetric standard model. We

  9. Dark matter searches with Cherenkov telescopes: nearby dwarf galaxies or local galaxy clusters?

    International Nuclear Information System (INIS)

    In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC 5813 and NGC 5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for present and future IACTs in the framework of the constrained minimal supersymmetric standard model. We

  10. Dark Matter Searches with Cherenkov Telescopes: Nearby Dwarf Galaxies or Local Galaxy Clusters?

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Conde, Miguel A.; /KIPAC, Menlo Park /SLAC /IAC, La Laguna /Laguna U., Tenerife; Cannoni, Mirco; /Huelva U.; Zandanel, Fabio; /IAA, Granada; Gomez, Mario E.; /Huelva U.; Prada, Francisco; /IAA, Granada

    2012-06-06

    In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC 5813 and NGC 5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for present and future IACTs in the framework of the constrained minimal supersymmetric standard model. We

  11. WINGS: A WIde-field Nearby Galaxy-cluster Survey. II. Deep optical photometry of 77 nearby clusters

    Science.gov (United States)

    Varela, J.; D'Onofrio, M.; Marmo, C.; Fasano, G.; Bettoni, D.; Cava, A.; Couch, W. J.; Dressler, A.; Kjærgaard, P.; Moles, M.; Pignatelli, E.; Poggianti, B. M.; Valentinuzzi, T.

    2009-04-01

    Context: This is the second paper of a series devoted to the WIde Field Nearby Galaxy-cluster Survey (WINGS). WINGS is a long term project which is gathering wide-field, multi-band imaging and spectroscopy of galaxies in a complete sample of 77 X-ray selected, nearby clusters (0.04 Issac Newton Telescope (2.5 m-INT) sited at Roque de los Muchachos (La Palma, Spain), and the MPG/ESO-2.2 m Telescope sited at La Silla (Chile). Appendices are only available in electronic form at http://www.aanda.org Catalog is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/497/667

  12. High-J CO SLEDs in nearby infrared bright galaxies observed by Herschel-PACS

    CERN Document Server

    Mashian, N; Sternberg, A; Janssen, A; Hailey-Dunsheath, S; Fischer, J; Contursi, A; Gonzalez-Alfonso, E; Gracia-Carpio, J; Poglitsch, A; Veilleux, S; Davies, R; Genzel, R; Lutz, D; Tacconi, L; Verma, A; Weiß, A; Polisensky, E; Nikola, T

    2014-01-01

    We report the detection of far-infrared (FIR) CO rotational emission from nearby active galactic nuclei (AGN) and starburst galaxies, as well as several merging systems and Ultra-Luminous Infrared Galaxies (ULIRGs). Using Herschel-PACS, we have detected transitions in the J$_{upp}$ = 14 - 20 range ($\\lambda \\sim$ 130 - 185 $\\mu$m, $\

  13. The host galaxy/AGN connection in nearby early-type galaxies. Is there a miniature radio-galaxy in every "core" galaxy?

    OpenAIRE

    Balmaverde, B.; Capetti, A.

    2005-01-01

    This is the second of a series of three papers exploring the connection between the multiwavelength properties of AGN in nearby early-type galaxies and the characteristics of their hosts. In Capetti et al. (2005) we presented a study of the surface brightness profiles for the 65 objects with available archival HST images out of the 116 radio-detected galaxies. We classified early-type galaxies into ``core'' and ``power-law'' galaxies, discriminating on the basis of the slope of their nuclear ...

  14. Constraints on decaying dark matter from Fermi observations of nearby galaxies and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Dugger, Leanna; Profumo, Stefano [Department of Astronomy and Department of Physics, University of California Berkeley, 601 Campbell Hall, Berkeley, CA (United States); Jeltema, Tesla E., E-mail: greentee01@gmail.com, E-mail: tesla@ucolick.org, E-mail: profumo@scipp.ucsc.edu [UCO/Lick Observatories, 1156 High St., Santa Cruz, CA 95064 (United States)

    2010-12-01

    We analyze the impact of Fermi gamma-ray observations (primarily non-detections) of selected nearby galaxies, including dwarf spheroidals, and of clusters of galaxies on decaying dark matter models. We show that the fact that galaxy clusters do not shine in gamma rays puts the most stringent limits available to-date on the lifetime of dark matter particles for a wide range of particle masses and decay final states. In particular, our results put strong constraints on the possibility of ascribing to decaying dark matter both the increasing positron fraction reported by PAMELA and the high-energy feature in the electron-positron spectrum measured by Fermi. Observations of nearby dwarf galaxies and of the Andromeda Galaxy (M31) do not provide as strong limits as those from galaxy clusters, while still improving on previous constraints in some cases.

  15. Constraints on Decaying Dark Matter from Fermi Observations of Nearby Galaxies and Clusters

    CERN Document Server

    Dugger, Leanna; Profumo, Stefano

    2010-01-01

    We analyze the impact of Fermi gamma-ray observations (primarily non-detections) of selected nearby galaxies, including dwarf spheroidals, and of clusters of galaxies on decaying dark matter models. We show that the fact that galaxy clusters do not shine in gamma rays puts the most stringent limits available to-date on the lifetime of dark matter particles for a wide range of particle masses and decay final states. In particular, our results rule out the possibility of ascribing to decaying dark matter both the increasing positron fraction reported by PAMELA and the high-energy feature in the electron-positron spectrum measured by Fermi. Observations of nearby dwarf galaxies and of the Andromeda Galaxy (M31) do not provide as strong constraints as those from galaxy clusters, while still improving on previous limits in some cases.

  16. The structure of nearby clusters of galaxies Hierarchical clustering and an application to the Leo region

    CERN Document Server

    Materne, J

    1978-01-01

    A new method of classifying groups of galaxies, called hierarchical clustering, is presented as a tool for the investigation of nearby groups of galaxies. The method is free from model assumptions about the groups. The scaling of the different coordinates is necessary, and the level from which one accepts the groups as real has to be determined. Hierarchical clustering is applied to an unbiased sample of galaxies in the Leo region. Five distinct groups result which have reasonable physical properties, such as low crossing times and conservative mass-to-light ratios, and which follow a radial velocity- luminosity relation. Only 4 out of 39 galaxies were adopted as field galaxies. (27 refs).

  17. New Low Surface Brightness Dwarf Galaxies Detected Around Nearby Spirals

    OpenAIRE

    Karachentsev, I. D.; Riepe, P.; Zilch, T.; Blauensteiner, M.; Elvov, M.; Hochleitner, P.; Hubl, B.; Kerschhuber, G.; Küppers, S.; Neyer, F.; Pölzl, R.; Remmel, P.; Schneider, O.; Sparenberg, R.; Trulson, U.

    2015-01-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC,672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC,2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their abs...

  18. Nearby galaxies as pointers to a better theory of cosmic evolution.

    Science.gov (United States)

    Peebles, P J E; Nusser, Adi

    2010-06-01

    The great advances in the network of cosmological tests show that the relativistic Big Bang theory is a good description of our expanding Universe. However, the properties of nearby galaxies that can be observed in greatest detail suggest that a better theory would describe a mechanism by which matter is more rapidly gathered into galaxies and groups of galaxies. This more rapid growth occurs in some theoretical ideas now under discussion.

  19. Properties of H II Regions in the Centers of Nearby Galaxies

    CERN Document Server

    Ho, L C; Sargent, W L W; Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W.

    1997-01-01

    As part of an optical spectroscopic survey of nearby, bright galaxies, we have identified a sample of over 200 emission-line nuclei having optical spectra resembling those of giant extragalactic H II regions. Such "H II nuclei," powered by young, massive stars, are found in a substantial fraction of nearby galaxies, especially those of late Hubble type. This paper summarizes the observational characteristics of H II nuclei, contrasts the variation of their properties with Hubble type, and compares the nuclear H II regions with those found in galaxy disks. Similarities and differences between H II nuclei and luminous starburst nuclei are additionally noted.

  20. Planck early results. XVI. The Planck view of nearby galaxies

    DEFF Research Database (Denmark)

    Bucher, M.; Delabrouille, J.; Giraud-Héraud, Y.;

    2011-01-01

    Theall-sky coverage of the Planck Early Release Compact Source Catalogue (ERCSC) provides an unsurpassed survey of galaxies at submillimetre (submm) wavelengths, representing a major improvement in the numbers of galaxies detected, as well as the range of far-IR/submm wavelengths over which they ...

  1. The Dwarf Galaxy Population in Nearby Groups. The data

    CERN Document Server

    Carrasco, E R; Infante, L; Carrasco, Eleazar R.; Oliveira, Claudia M. de; Infante, Leopoldo

    2006-01-01

    We used V and I CCD photometry to search for low-surface brightness dwarf galaxies (LSBD) in the central ( 22.5 V mag/arcsec^2, h > 1.5 arcsec, and diameters larger than 1.2 h^-1 kpc. Twenty of the eighty galaxies are extended LSB galaxies that were detected only on smoothed images, after masking all high surface brightness objects. The completeness in the detection is ~80% for galaxies with V<=20 and 22.5galaxies in smoothed images instead. The detected LSBD galaxies are highly concentrated towards the center of the four groups in the inner 250 h^-1 kpc. The best fit power-law slope of the surface density distribution is, on average, beta ~ -1.5 (R < 250 h^-1 kpc), in agreement with the values found for satellites dwarfs around isolated E/S0 galaxies and in X-ray groups. The LSBD galaxies in the Mv-mu0 plane does not show a clear c...

  2. The Halos and Environments of Nearby Galaxies (HERON) Survey

    CERN Document Server

    Rich, R Michael; Bullock, James; Burkert, Andreas; Collins, Michelle; de Groot, Laura; Kennefick, Julia; Koch, Andreas; Longstaff, Francis; Sales, Laura

    2016-01-01

    We have used dedicated 0.7m telescopes in California and Israel to image the halos of ~200 galaxies in the Local Volume to 29 mag/sq arcsec, the sample mainly drawn from the 2MASS Large Galaxy Atlas (LGA). We supplement the LGA sample with dwarf galaxies and more distant giant ellipticals. Low surface brightness halos exceeding 50 kpc in diameter are found only in galaxies more luminous than L* and classic interaction signatures are relatively infrequent. Halo diameter is correlated with total galaxy luminosity. Extended low surface brightness halos are present even in galaxies as faint as M_V=-18. Edge-on galaxies with boxy bulges tend to lack extended spheroidal halos, while those with large classical bulges exhibit extended round halos, supporting the notions that boxy or barlike bulges originate from disks. Most face-on spiral galaxies present features that appear to be irregular extensions of spiral arms, although rare cases show smooth boundaries with no sign of star formation. Although we serendipitous...

  3. VLA-ANGST: A high-resolution HI Survey of Nearby Dwarf Galaxies

    CERN Document Server

    Ott, Juergen; Warren, Steven R; Skillman, Evan D; Dalcanton, Julianne J; Walter, Fabian; de Blok, W J G; Koribalski, Baerbel; West, Andrew A

    2012-01-01

    We present the "Very Large Array survey of Advanced Camera for Surveys Nearby Galaxy Survey Treasury galaxies (VLA-ANGST)." VLA-ANGST is a National Radio Astronomy Observatory Large Program consisting of high spectral (0.6-2.6 km/s) and spatial (~6") resolution observations of neutral, atomic hydrogen (HI) emission toward 35 nearby dwarf galaxies from the ANGST survey. ANGST is a systematic HST survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D\\lesssim4 Mpc). VLA-ANGST provides VLA HI observations of the sub-sample of ANGST galaxies with recent star formation that are observable from the northern hemisphere and that were not observed in the "The HI Nearby Galaxy Survey" (THINGS). The overarching scientific goal of VLA-ANGST is to investigate fundamental characteristics of the neutral interstellar medium (ISM) of dwarf galaxies. Here we describe the VLA observations, the data reduction, and the final VLA-ANGST data products. We pre...

  4. New Low Surface Brightness Dwarf Galaxies Detected Around Nearby Spirals

    CERN Document Server

    Karachentsev, I D; Zilch, T; Blauensteiner, M; Elvov, M; Hochleitner, P; Hubl, B; Kerschhuber, G; Küppers, S; Neyer, F; Pölzl, R; Remmel, P; Schneider, O; Sparenberg, R; Trulson, U; Willems, G; Ziegler, H

    2015-01-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC,672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC,2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their absolute magnitudes are in the range of -8.6 > M_B > -13.3, their effective diameters are 0.4-4.7 kpc, and the average surface brightness is 26.1 mag/sq arcsec. The mean linear projected separation of the satellite candidates from the host galaxies is 73 kpc. Our spectroscopic observations of two LSB dwarfs with the Russian 6-meter telescope confirm their physical connection to the host galaxies NGC,891 and NGC,2683.

  5. New low surface brightness dwarf galaxies detected around nearby spirals

    Science.gov (United States)

    Karachentsev, I. D.; Riepe, P.; Zilch, T.; Blauensteiner, M.; Elvov, M.; Hochleitner, P.; Hubl, B.; Kerschhuber, G.; Küppers, S.; Neyer, F.; Pölzl, R.; Remmel, P.; Schneider, O.; Sparenberg, R.; Trulson, U.; Willems, G.; Ziegler, H.

    2015-10-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their absolute magnitudes are in the range of -8.6 > M B > -13.3, their effective diameters are 0.4-4.7 kpc, and the average surface brightness is 26ṃ1/□″. The mean linear projected separation of the satellite candidates from the host galaxies is 73 kpc. Our spectroscopic observations of two LSB dwarfs with the Russian 6-meter telescope confirm their physical connection to the host galaxies NGC891 and NGC2683.

  6. The Nature of Starbursts: I. The Star Formation Histories of Eighteen Nearby Starburst Dwarf Galaxies

    CERN Document Server

    McQuinn, Kristen B W; Cannon, John M; Dalcanton, Julianne; Dolphin, Andrew; Hidalgo-Rodríguez, Sebastian; Holtzman, Jon; Stark, David; Weisz, Daniel; Williams, Benjamin

    2010-01-01

    We use archival HST observations of resolved stellar populations to derive the star formation histories (SFHs) of 18 nearby starburst dwarf galaxies. In this first paper we present the observations, color-magnitude diagrams, and the SFHs of the 18 starburst galaxies, based on a homogeneous approach to the data reduction, differential extinction, and treatment of photometric completeness. We adopt a star formation rate (SFR) threshold normalized to the average SFR of the individual system as a metric for classifying starbursts in SFHs derived from resolved stellar populations. This choice facilitates finding not only currently bursting galaxies but also "fossil" bursts increasing the sample size of starburst galaxies in the nearby (D100 Myr temporal baseline is thus fundamental to any starburst definition or identification method. The longer lived bursts rule out rapid "self-quenching" of starbursts on global scales. The bursting galaxies' gas consumption timescales are shorter than the Hubble time for all but...

  7. THE ADVANCED CAMERA FOR SURVEYS NEARBY GALAXY SURVEY TREASURY. IV. THE STAR FORMATION HISTORY OF NGC 2976

    International Nuclear Information System (INIS)

    We present resolved stellar photometry of NGC 2976 obtained with the Advanced Camera for Surveys (ACS) as part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. The data cover the radial extent of the major axis of the disk out to 6 kpc, or ∼6 scale lengths. The outer disk was imaged to a depth of MF606W ∼ 1, and an inner field was imaged to the crowding limit at a depth of MF606W ∼ -1. Through detailed analysis and modeling of the resulting color-magnitude diagrams, we have reconstructed the star formation history (SFH) of the stellar populations currently residing in these portions of the galaxy, finding similar ancient populations at all radii but significantly different young populations at increasing radii. In particular, outside of the well-measured break in the disk surface brightness profile, the age of the youngest population increases with distance from the galaxy center, suggesting that star formation is shutting down from the outside-in. We use our measured SFH, along with H I surface density measurements, to reconstruct the surface density profile of the disk during previous epochs. Comparisons between the recovered star formation rates and reconstructed gas densities at previous epochs are consistent with star formation following the Schmidt law during the past 0.5 Gyr, but with a drop in star formation efficiency at low gas densities, as seen in local galaxies at the present day. The current rate and gas density suggest that rapid star formation in NGC 2976 is currently in the process of ceasing from the outside-in due to gas depletion. This process of outer disk gas depletion and inner disk star formation was likely triggered by an interaction with the core of the M81 group ∼>1 Gyr ago that stripped the gas from the galaxy halo and/or triggered gas inflow from the outer disk toward the galaxy center.

  8. A novel approach for identifying host galaxies of nearby FRBs

    CERN Document Server

    Rane, Akshaya

    2016-01-01

    We report on a search for host galaxies of a subset of Rotating Radio Transients (RRATs) that possess a dispersion measure (DM) near or above the maximum Galactic value in their direction. These RRATs could have an extragalactic origin and therefore be Fast Radio Bursts (FRBs). The sizes of related galaxies on the sky at such short distances are comparable to the beam size of a single-dish telescope (for example, the $7.0'$ radius of the Parkes beam). Hence the association, if found, could be more definitive as compared to finding host galaxies for more distant FRBs. We did not find any host galaxy associated with six RRATs near the maximum Galactic DM. This result is consistent with the fact that the probability of finding an FRB host galaxy within this volume is also very small. We propose that future follow-up observations of such RRATs be carried out in searching for local host galaxies as well as the sources of FRBs.

  9. DGSAT: Dwarf Galaxy Survey with Amateur Telescopes. I. Discovery of low surface brightness systems around nearby spiral galaxies

    Science.gov (United States)

    Javanmardi, B.; Martinez-Delgado, D.; Kroupa, P.; Henkel, C.; Crawford, K.; Teuwen, K.; Gabany, R. J.; Hanson, M.; Chonis, T. S.; Neyer, F.

    2016-04-01

    Context. We introduce the Dwarf Galaxy Survey with Amateur Telescopes (DGSAT) project and report the discovery of eleven low surface brightness (LSB) galaxies in the fields of the nearby galaxies NGC 2683, NGC 3628, NGC 4594 (M 104), NGC 4631, NGC 5457 (M 101), and NGC 7814. Aims: The DGSAT project aims to use the potential of small-sized telescopes to probe LSB features around large galaxies and to increase the sample size of the dwarf satellite galaxies in the Local Volume. Methods: Using long exposure images, fields of the target spiral galaxies are explored for extended LSB objects. After identifying dwarf galaxy candidates, their observed properties are extracted by fitting models to their light profiles. Results: We find three, one, three, one, one, and two new LSB galaxies in the fields of NGC 2683, 3628, 4594, 4631, 5457, and 7814, respectively. In addition to the newly found galaxies, we analyse the structural properties of nine already known galaxies. All of these 20 dwarf galaxy candidates have effective surface brightnesses in the range 25.3 ≲ μe ≲ 28.8 mag arcsec-2 and are fit with Sersic profiles with indices n ≲ 1. Assuming that they are in the vicinity of the above mentioned massive galaxies, their r-band absolute magnitudes, their effective radii, and their luminosities are in the ranges -15.6 ≲ Mr ≲ -7.8, 160 pc ≲ Re ≲ 4.1 kpc, and 0.1 × 106 ≲ (L/L⊙)r ≲ 127 × 106, respectively. To determine whether these LSB galaxies are indeed satellites of the above mentioned massive galaxies, their distances need to be determined via further observations. Conclusions: Using small telescopes, we are readily able to detect LSB galaxies with similar properties to the known dwarf galaxies of the Local Group.

  10. Hunting for Supermassive Black Holes in Nearby Galaxies with the Hobby-Eberly Telescope

    CERN Document Server

    Bosch, Remco van den; Gültekin, Kayhan; Yıldırım, Akin; Walsh, Jonelle

    2015-01-01

    We have conducted an optical long-slit spectroscopic survey of 1022 galaxies using the 10m Hobby-Eberly Telescope (HET) at McDonald Observatory. The main goal of the HET Massive Galaxy Survey (HETMGS) is to find nearby galaxies that are suitable for black hole mass measurements. In order to measure accurately the black hole mass, one should kinematically resolve the region where the black hole dominates the gravitational potential. For most galaxies, this region is much less than an arcsecond. Thus, black hole masses are best measured in nearby galaxies with telescopes that obtain high-spatial resolution. The HETMGS focuses on those galaxies predicted to have the largest sphere-of-influence, based on published stellar velocity dispersions or the galaxy fundamental plane. To ensure coverage over galaxy types, the survey targets those galaxies across a face-on projection of the fundamental plane. We present the sample selection and resulting data products from the long-slit observations, including central stell...

  11. Magnetic Fields in a Sample of Nearby Spiral Galaxies

    CERN Document Server

    Van Eck, Cameron; Shukurov, Anvar; Fletcher, Andrew

    2014-01-01

    Both observations and modelling of magnetic fields in the diffuse interstellar gas of spiral galaxies are well developed but the theory has been confronted with observations for only a handful of individual galaxies. There is now sufficient data to consider statistical properties of galactic magnetic fields. We have collected data from the literature on the magnetic fields and interstellar media (ISM) of 20 spiral galaxies, and tested for various physically motivated correlations between magnetic field and ISM parameters. Clear correlations emerge between the total magnetic field strength and molecular gas density as well as the star formation rate. The magnetic pitch angle exhibits correlations with the total gas density, the star formation rate and the strength of the axisymmetric component of the mean magnetic field. The total and mean magnetic field strengths exhibit noticeable degree of correlation, suggesting a universal behaviour of the degree of order in galactic magnetic fields. We also compare the p...

  12. Mass-to-light ratios of nearby groups of galaxies

    CERN Document Server

    Materne, J

    1980-01-01

    The application of a probability density function gives the possibility of determining groups of galaxies and membership probabilities of the galaxies in a reliable unbiased way. For the five nearest groups so defined, the mean mass-to-light ratio was derived using the concept of negative energy. These groups have a mass-to- light ratio of 16 M/sub (.)//L/sub (.)/. The probability function gives also the possibility of deriving masses of groups in a direct and independent way. (22 refs).

  13. Quark Nugget Dark Matter: Comparison with radio observations of nearby galaxies

    CERN Document Server

    Lawson, K

    2015-01-01

    It has been recently claimed that radio observations of nearby spiral galaxies essentially rule out a dark matter source for the galactic haze. Here we consider the low energy thermal emission from a quark nugget dark matter model in the context of microwave emission from the galactic centre and radio observations of nearby Milky Way like galaxies. We demonstrate that observed emission levels do not strongly constrain this specific dark matter candidate across a broad range of the allowed parameter space in drastic contrast with conventional dark matter models based on the WIMP paradigm.

  14. A NuSTAR survey of nearby ultraluminous infrared galaxies

    DEFF Research Database (Denmark)

    Teng, Stacy H.; Rigby, Jane R.; Stern, Daniel;

    2015-01-01

    We present a Nuclear Spectroscopic Telescope Array (NuSTAR), Chandra, and XMM-Newton survey of nine of the nearest ultraluminous infrared galaxies (ULIRGs). The unprecedented sensitivity of NuSTAR at energies above 10 keV enables spectral modeling with far better precision than was previously pos...

  15. Spectra of Nearby Galaxies Measured with a New Very Broadband Receiver

    CERN Document Server

    Narayanan, Gopal; Erickson, Neal R; Chung, Aeree; Heyer, Mark H; Yun, Min; Irvine, William M; 10.1017/S1743921308021698

    2008-01-01

    Three-millimeter-wavelength spectra of a number of nearby galaxies have been obtained at the Five College Radio Astronomy Observatory (FCRAO) using a new, very broadband receiver. This instrument, which we call the Redshift Search Receiver, has an instantaneous bandwidth of 36 GHz and operates from 74 to 110.5 GHz. The receiver has been built at UMass/FCRAO to be part of the initial instrumentation for the Large Millimeter Telescope (LMT) and is intended primarily for determination of the redshift of distant, dust-obscured galaxies. It is being tested on the FCRAO 14m by measuring the 3mm spectra of a number of nearby galaxies. There are interesting differences in the chemistry of these galaxies.

  16. The Galactic Center compared with nuclei of nearby galaxies

    CERN Document Server

    Combes, F

    2016-01-01

    Understanding our Galactic Center is easier with insights from nearby galactic nuclei. Both the star formation activity in nuclear gas disks, driven by bars and nuclear bars, and the fueling of low-luminosity AGN, followed by feedback of jets, driving molecular outflows, were certainly present in our Galactic Center, which appears now quenched. Comparisons and diagnostics are reviewed, in particular of m=2 and m=1 modes, lopsidedness, different disk orientations, and fossil evidences of activity and feedback.

  17. Percolation Properties of Nearby Large-Scale Structures: Every Galaxy has a Neighbour

    CERN Document Server

    Fairall, A; Pretorius, M L; Wiehahn, M; McBride, V; de Vaux, G; Woudt, P A; Fairall, Anthony

    2004-01-01

    The distribution of nearby (cz < 7500 km/s) galaxies has been explored by minimal spanning trees; allowance has been made for the drastic decrease of data with distance. The investigation finds that all galaxies are members of irregular elongated large-scale structures; there are no `field galaxies'. Based on our local large-scale structure, every galaxy appears to have a neighbouring galaxy within <100 km/s (1.4 h_{70}^{-1} Mpc) of redshift space, and thereby all galaxies are found to lie in filaments or tree configurations. Every large-scale structure appears to have a neighbouring large-scale structure within <700 km/s (10 h_{70}^{-1} Mpc), such that large-scale structures interconnect to form a continuous labyrinth.

  18. What Powers the Compact Radio Emission in Nearby Elliptical and S0 Galaxies?

    OpenAIRE

    Ho, Luis C.

    1998-01-01

    Many nearby early-type (elliptical and S0) galaxies contain weak (milli-Jansky level) nuclear radio sources on scales a few hundred parsecs or less. The origin of the radio emission, however, has remained unclear, especially in volume-limited samples that select intrinsically less luminous galaxies. Both active galactic nuclei and nuclear star formation have been suggested as possible mechanisms for producing the radio emission. This paper utilizes optical spectroscopic information to address...

  19. Host Galaxies of Type Ia Supernovae from the Nearby Supernova Factory

    Science.gov (United States)

    Childress, M.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Gangler, E.; Guy, J.; Hsiao, E. Y.; Kerschhaggl, M.; Kim, A. G.; Kowalski, M.; Loken, S.; Nugent, P.; Paech, K.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.; Wu, C.

    2013-06-01

    We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory. Combining Galaxy Evolution Explorer (GALEX) UV data with optical and near-infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high-precision redshifts, gas-phase metallicities, and Hα-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from Sloan Digital Sky Survey (SDSS) for stellar masses log(M */M ⊙) > 8.5 where the relation is well defined. The star formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, though this comparison is limited by systematic uncertainties in SFR measurements. Our analysis indicates that SN Ia host galaxies are, on average, typical representatives of normal field galaxies.

  20. ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. III. AN EXTREMELY METAL DEFICIENT GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Skillman, Evan D.; Berg, Danielle A.; Olive, Keith A.; McQuinn, Kristen B. W., E-mail: skillman@astro.umn.edu, E-mail: berg@astro.umn.edu, E-mail: olive@physics.umn.edu, E-mail: kmcquinn@astro.umn.edu [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States); and others

    2013-07-01

    We present KPNO 4 m and LBT/MODS spectroscopic observations of an H II region in the nearby dwarf irregular galaxy Leo P discovered recently in the Arecibo ALFALFA survey. In both observations, we are able to accurately measure the temperature sensitive [O III] {lambda}4363 line and determine a ''direct'' oxygen abundance of 12 + log(O/H) = 7.17 {+-} 0.04. Thus, Leo P is an extremely metal deficient (XMD) galaxy, and, indeed, one of the most metal deficient star-forming galaxies ever observed. For its estimated luminosity, Leo P is consistent with the relationship between luminosity and oxygen abundance seen in nearby dwarf galaxies. Leo P shows normal {alpha} element abundance ratios (Ne/O, S/O, and Ar/O) when compared to other XMD galaxies, but elevated N/O, consistent with the ''delayed release'' hypothesis for N/O abundances. We derive a helium mass fraction of 0.2509{sup +0.0184}{sub -0.0123}, which compares well with the WMAP + BBN prediction of 0.2483 {+-} 0.0002 for the primordial helium abundance. We suggest that surveys of very low mass galaxies compete well with emission line galaxy surveys for finding XMD galaxies. It is possible that XMD galaxies may be divided into two classes: the relatively rare XMD emission line galaxies which are associated with starbursts triggered by infall of low-metallicity gas and the more common, relatively quiescent XMD galaxies like Leo P, with very low chemical abundances due to their intrinsically small masses.

  1. DGSAT: Dwarf Galaxy Survey with Amateur Telescopes I. Discovery of low surface brightness systems around nearby spiral galaxies

    CERN Document Server

    Javanmardi, B; Kroupa, P; Henkel, C; Crawford, K; Teuwen, K; Gabany, R J; Hanson, M; Neyer, F

    2015-01-01

    Context: We introduce the Dwarf Galaxy Survey with Amateur Telescopes (DGSAT) project and report the discovery of eleven Low Surface Brightness (LSB) galaxies in the fields of the nearby galaxies NGC 2683, NGC 3628, NGC 4594 (M104), NGC 4631, NGC 5457 (M101), and NGC7814. Aims: The DGSAT project aims at using the potential of small-sized telescopes to probe LSB features around large galaxies and to increase the sample size of the dwarf satellite galaxies in the Local Volume. Methods: Using long exposure images centred on the target, its field is explored for extended low surface brightness objects. After identifying dwarf galaxy candidates, their observed properties are extracted by fitting models to their light profiles. Results: We find three, one, three, one, one, and two new LSB galaxies in the fields of NGC 2683, 3628, 4594, 4631, 5457, and 7814, respectively. In addition to the newly found galaxies, we analyse the structural properties of 9 already known galaxies. All of these 20 dwarf galaxy candidates...

  2. Surface brightness fluctuation distances for nearby dwarf elliptical galaxies

    CERN Document Server

    Jerjen, H; Takalo, L; Coleman, M; Valtonen, M J; Jerjen, Helmut; Rekola, Rami; Takalo, Leo; Coleman, Matthew; Valtonen, Mauri

    2001-01-01

    We obtained B and R-band CCD images for the dwarf elliptical (dE) galaxies DDO44, UGC4998, KK98_77, DDO71, DDO113, and UGC7356 at the NOT. Using Fourier analysis technique we measure stellar R-band surface brightness fluctuations (SBFs) and magnitudes in 29 different fields of the galaxies. Independent tip of the red giant branch distances for DDO44, KK98_77, DDO71 are used to convert their set of apparent into absolute SBF magnitudes. The results are combined with the local (B-R) colours and compared with the (B-R)-\\bar{M}_R relation for mainly old, metal-poor stellar populations as predicted by Worthey's population synthesis models using Padova isochrones. While the colour dependency of the theoretical relation is confirmed by the empirical data, we find a systematic zero point offset between observations and theory in the sense that models are too faint by 0.13+-0.02 mag. Based on these findings we establish a new semiempirical calibration of the SBF method as distance indicator for dE galaxies with an est...

  3. Probing the Central Regions of Nearby Compact Elliptical Galaxies

    CERN Document Server

    Davidge, T J; McGregor, P J

    2008-01-01

    K-band spectroscopic observations recorded with NIFS+ALTAIR on Gemini North are used to probe the central arcsec of the compact elliptical galaxies NGC 4486B, NGC 5846A, and M32. The angular resolution of these data is ~0.1 arcsec FWHM. The central stellar contents of NGC 4486B and NGC 5846A are similar, in the sense that they occupy the same regions of the (Ca I, 12CO), (Na I, 12CO) and (13CO, 12CO) diagrams. The NGC 4486B and NGC 5846A observations depart from the sequence defined by solar neighborhood giants in the (Na I, 12CO) diagram, in a sense that is consistent with both galaxies having non-solar chemical mixtures. For comparison, the M32 data is consistent with a chemical enrichment history like that in the Galactic disk; M32 could not have formed from the stripping of a larger elliptical galaxy. The behaviour of the near-infrared line indices as a function of radius is also investigated. The radial gradients that are present in NGC 4486B and NGC 5846A at large radii break down or reverse within the ...

  4. GALEX UV Color Relations for Nearby Early-Type Galaxies

    CERN Document Server

    Donas, J; Rich, R M; Yi, S K; Lee, Y W; Boselli, A; De Paz, A G; Boissier, S; Charlot, S; Salim, S; Bianchi, L; Barlow, T A; Forster, K; Friedman, P G; Heckman, T M; Madore, B F; Martin, D C; Milliard, B; Morrissey, P; Neff, S G; Schiminovich, D; Seibert, M; Small, T; Szalay, A S; Welsh, B Y; Wyder, T K; Donas, Jose; Deharveng, Jean-Michel; Yi, Sukyoung K.; Lee, Young-Wook; Boselli, Alessandro; Paz, Armando Gil de; Boissier, Samuel; Charlot, Stephane; Salim, Samir; Bianchi, Luciana; Barlow, Tom A.; Forster, Karl; Friedman, Peter G.; Heckman, Timothy M.; Madore, Barry F.; Milliard, Bruno; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Seibert, Mark; Small, Todd; Szalay, Alex S.; Welsh, Barry Y.; Wyder, Ted K.

    2006-01-01

    We use GALEX/optical photometry to construct color-color relationships for early-type galaxies sorted by morphological type. We have matched objects in the GALEX GR1 public release and the first IR1.1 internal release, with the RC3 early-type galaxies having a morphological type -5.5galaxies with a reliable GALEX pipeline photometry in the far-UV and near-UV bands. This sample is divided into Ellipticals (-5.5

  5. Water vapor in nearby infrared galaxies as probed by Herschel

    CERN Document Server

    Yang, Chentao; Omont, A; Liu, Daizhong; Isaak, K G; Downes, D; van der Werf, P P; Lu, Nanyao

    2013-01-01

    We report the first systematic study of the submillimeter water vapor rotational emission lines in infrared (IR) galaxies based on the Fourier Transform Spectrometer (FTS) data of {\\it Herschel} SPIRE. Among the 176 galaxies with publicly available FTS data, 45 have at least one H$_2$O emission line detected. The H$_2$O line luminosities range from $\\sim 1 \\times 10^5$ L$_{\\odot}$ to $\\sim 5 \\times 10^7$ L$_{\\odot}$ while the total IR luminosities (L$_\\mathrm{IR}$) have a similar spread ($\\sim$1-300 $\\times 10^{10}$ L$_{\\odot}$). In addition, emission lines of H$_2$O$^+$ and H$_2^{18}$O are also detected. H$_2$O is found, for most galaxies, to be the strongest molecular emitter after CO in FTS spectra. The luminosity of the five most important H$_2$O lines is near-linearly correlated with L$_\\mathrm{IR}$ no matter strong AGN signature is present or not. However, the luminosity of H$_2$O(2$_{11}-2_{02}$) and H$_2$O(2$_{20}-2_{11}$) appears to increase slightly faster than linear with L$_\\mathrm{IR}$. Although ...

  6. Far-infrared colours of nearby late-type galaxies in the Herschel Reference Survey

    OpenAIRE

    Boselli, A.; Ciesla, L.; Cortese, L.; Buat, V.; Boquien, M.; Bendo, GJ; Boissier, S.; Eales, S; Gavazzi, G.; Hughes, TM; Pohlen, M.; Smith, MWL; Baes, Maarten; S. Bianchi; Clements, DL

    2012-01-01

    We study the far infrared (60-500 mu m) colours of late-type galaxies in the Herschel Reference Survey, a K-band selected, volume limited sample of nearby galaxies. The far infrared colours are correlated with each other, with tighter correlations for the indices that are closer in wavelength. We also compare the different colour indices to various tracers of the physical properties of the target galaxies, such as the surface brightness of the ionising and non-ionising stellar radiation, the ...

  7. FIR colours of nearby late-type galaxies in the Herschel Reference Survey

    OpenAIRE

    Boselli, A.; Ciesla, L.; Cortese, L.; Buat, V.; Boquien, M.; G.J. Bendo; Boissier, S.; Eales, S; Gavazzi, G.; Hughes, T. M.; Pohlen, M.; Smith, M. W. L.; Baes, M.; S. Bianchi; Clements, D. L.

    2012-01-01

    We study the far infrared (60-500 $\\mu$m) colours of late-type galaxies in the $Herschel$ Reference Survey, a K-band selected, volume limited sample of nearby galaxies. The far infrared colours are correlated with each other, with tighter correlations for the indices that are closer in wavelength. We also compare the different colour indices to various tracers of the physical properties of the target galaxies, such as the surface brightness of the ionising and non-ionising stellar radiation, ...

  8. Extraplanar diffuse ionized gas in a small sample of nearby edge-on galaxies

    OpenAIRE

    Rossa, J.; Dettmar, R. -J.

    2000-01-01

    We present narrowband H-alpha imaging data of a small survey of nearby edge-on spiral galaxies, aiming at the detection of `extraplanar' diffuse ionized gas (DIG). A few of our studied edge-on spirals show signs of disk-halo interaction (DHI), where extended line emission far above the galactic plane of these galaxies is detected. In some cases an extraplanar diffuse ionized gas (eDIG) layer is discovered, e.g., NGC4634, NGC 3044, while other galaxies show only filamentary features reaching i...

  9. VizieR Online Data Catalog: Optical supernova remnants in nearby galaxies (Vucetic+, 2015)

    Science.gov (United States)

    Vucetic, M. M.; Arbutina, B.; Urosevic, D.

    2015-09-01

    To estimate the contribution from SNRs to the total Hα emission used to determine SFRs in a galaxy, we searched the literature for all galaxies that have optically identified SNRs. In total, there are 25 of them (excluding the Milky Way). In following tables we give data for 18 nearby galaxies which have been surveyed for optical supernova remnants (SNRs). In each table we give coordinates, Hα fluxes, diameters and [SII]/Hα emission line ratios for detected SNRs, found in literature. (19 data files).

  10. Optical observations of the nearby galaxy IC342 with narrow band [SII] and Hα filters. I

    Directory of Open Access Journals (Sweden)

    Vučetić M.M.

    2013-01-01

    Full Text Available We present observations of a portion of the nearby spiral galaxy IC342 using narrow band [SII] and Hα filters. These observations were carried out in November 2011 with the 2m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper we report coordinates, diameters, Hα and [SII] fluxes for 203 HII regions detected in two fields of view in IC342 galaxy. The number of detected HII regions is 5 times higher than previously known in these two parts of the galaxy. [Projekat Ministarstva nauke Republike Srbije, br. 176005: Emission nebulae: structure and evolution

  11. Constraining Stellar Feedback: Shock-ionized Gas in Nearby Starburst Galaxies

    CERN Document Server

    Hong, Sungryong; Gallagher, John S; Martin, Crystal L; Conselice, Christopher J; Pellerin, Anne

    2013-01-01

    (abridged) We investigate the properties of feedback-driven shocks in 8 nearby starburst galaxies using narrow-band imaging data from the Hubble Space Telescope (HST). We identify the shock--ionized component via the line diagnostic diagram \\oiii/\\hb vs. \\sii (or \

  12. The Frequency of Tidal Features Associated with Nearby Luminous Elliptical Galaxies from a Statistically Complete Sample

    CERN Document Server

    Tal, Tomer; Nelan, Jenica; Bezanson, Rachel

    2009-01-01

    We present a deep broadband optical imaging study of a complete sample of luminous elliptical galaxies (M_B<-20) at distances 15 Mpc - 50 Mpc, selected from the Tully catalog of nearby galaxies. The images are flat to ~0.35% across the 20' field and reach a V band depth of 27.7 mag arcsec^-2. We derive an objective tidal interaction parameter for all galaxies and find that 73% of them show tidal disturbance signatures in their stellar bodies. This is the first time that such an analysis is done on a statistically complete sample and it confirms that tidal features in ellipticals are common even in the local Universe. From the dynamical time of the sample galaxies at the innermost radius where tidal features are detected we estimate the mass assembly rate of nearby ellipticals to be dM/M 0.2 per Gyr with large uncertainty. We explore the relation between gravitational interaction signatures and the galaxy environment and find that galaxies in clusters are less disturbed than group and field galaxies. We als...

  13. THE TRUE DURATIONS OF STARBURSTS: HUBBLE SPACE TELESCOPE OBSERVATIONS OF THREE NEARBY DWARF STARBURST GALAXIES

    International Nuclear Information System (INIS)

    The duration of a starburst is a fundamental parameter affecting the evolution of galaxies yet, to date, observational constraints on the durations of starbursts are not well established. Here we study the recent star formation histories of three nearby dwarf galaxies to rigorously quantify the duration of their starburst events using a uniform and consistent approach. We find that the bursts range from ∼200 to ∼400 Myr in duration resolving the tension between the shorter timescales often derived observationally with the longer timescales derived from dynamical arguments. If these three starbursts are typical of starbursts in dwarf galaxies, then the short timescales (3-10 Myr) associated with starbursts in previous studies are best understood as 'flickering' events which are simply small components of the larger starburst. In this sample of three nearby dwarfs, the bursts are not localized events. All three systems show bursting levels of star formation in regions of both high and low stellar density. The enhanced star formation moves around the galaxy during the bursts and covers a large fraction of the area of the galaxy. These massive, long-duration bursts can significantly affect the structure, dynamics, and chemical evolution of the host galaxy and can be the progenitors of 'superwinds' that drive much of the recently chemically enriched material from the galaxy into the intergalactic medium.

  14. The role of cold gas and environment on the stellar mass - metallicity relation of nearby galaxies

    CERN Document Server

    Hughes, T M; Boselli, A; Gavazzi, G; Davies, J I

    2012-01-01

    We investigate the relationship between stellar mass, metallicity and gas content for a magnitude- and volume-limited sample of 260 nearby late-type galaxies in different environments, from isolated galaxies to Virgo cluster members. We derive oxygen abundance estimates using new integrated, drift-scan optical spectroscopy and the base metallicity calibrations of Kewley & Ellison (2008). Combining these measurements with ultraviolet to near-infrared photometry and HI 21 cm line observations, we examine the relations between stellar mass, metallicity, gas mass fraction and star formation rate. We find that, at fixed stellar mass, galaxies with lower gas fractions typically also possess higher oxygen abundances. We also observe a relationship between gas fraction and metal content, whereby gas-poor galaxies are typically more metal-rich, and demonstrate that the removal of gas from the outskirts of spirals increases the observed average metallicity by approximately 0.1 dex. Although some cluster galaxies ar...

  15. Infrared Signature of Active Massive Black Holes in Nearby Dwarf Galaxies

    CERN Document Server

    Marleau, Francine R; Bianconi, Matteo; Habas, Rebecca

    2014-01-01

    We have identified 314 nearby galaxies that display the infrared signature of black hole activity. Of these, twelve lie within a distance of 11 Mpc, the nearest being EW Eri located only 50 kpc away. Using the Wide-field Infrared Survey Explorer (WISE) All-Sky Release Source Catalog, we examine the IR colors of a sample of known nearby dwarf galaxies in order to identify both unobscured (type 1) and obscured (type 2) active galactic nuclei in these low-mass systems. We estimate the stellar and black hole masses for our nearby dwarf galaxy sample and find that activity is detected in galaxies with stellar masses from 10^5 to 10^9 M_sun and that this activity is due to black holes with masses in the range 10^2-10^6 M_sun. The black hole masses probed here are several orders of magnitude smaller than previously reported for centrally located massive black holes. We examine the stellar mass versus black hole mass relationship in this low galaxy mass regime, and find that the existing relation extends to these low...

  16. Low dark matter content of the nearby early-type galaxy NGC 821

    Directory of Open Access Journals (Sweden)

    Samurović S.

    2014-01-01

    Full Text Available In this paper we analyze the kinematics and dynamics of the nearby early-type galaxy NGC 821 based on its globular clusters (GCs and planetary nebulae (PNe. We use PNe and GCs to extract the kinematics of NGC 821 which is then used for the dynamical modelling based on the Jeans equation. We apply the Jeans equation using the Newtonian mass-follows-light approach assuming constant mass-to-light ratio and find that using such an approach we can successfully fit the kinematic data. The inferred constant mass-to-light ratio, 4:2 < M=LB < 12:4 present throughout the whole galaxy, implies the lack of significant amount of dark matter. We also used three different MOND approaches and found that we can fit the kinematic data without the need for additional, dark, component. [Projekat Ministarstva nauke Republike Srbije, br. 176021: Visible and invisible matter in nearby galaxies: theory and observations

  17. NGC 1277: A MASSIVE COMPACT RELIC GALAXY IN THE NEARBY UNIVERSE

    Energy Technology Data Exchange (ETDEWEB)

    Trujillo, Ignacio; Vazdekis, Alexandre [Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205-La Laguna, Tenerife (Spain); Ferré-Mateu, Anna [Subaru Telescope, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Balcells, Marc [Isaac Newton Group of Telescopes, E-38700 Santa Cruz de La Palma, Canary Islands (Spain); Sánchez-Blázquez, Patricia, E-mail: trujillo@iac.es [Departamento de Física Teórica, Universidad Autónoma de Madrid, E-28049, Cantoblanco, Madrid (Spain)

    2014-01-10

    As early as 10 Gyr ago, galaxies with more than 10{sup 11} M {sub ☉} of stars already existed. While most of these massive galaxies must have subsequently transformed through on-going star formation and mergers with other galaxies, a small fraction (≲0.1%) may have survived untouched until today. Searches for such relic galaxies, useful windows to explore the early universe, have been inconclusive to date: galaxies with masses and sizes like those observed at high redshift (M {sub *} ≳ 10{sup 11} M {sub ☉}; R{sub e} ≲ 1.5 kpc) have been found in the local universe, but their stars are far too young for the galaxy to be a relic galaxy. This paper explores the first case of a nearby galaxy, NGC 1277 (at a distance of 73 Mpc in the Perseus galaxy cluster), which fulfills many criteria to be considered a relic galaxy. Using deep optical spectroscopy, we derive the star formation history along the structure of the galaxy: the stellar populations are uniformly old (>10 Gyr) with no evidence for more recent star formation episodes. The metallicity of their stars is super-solar ([Fe/H] = 0.20 ± 0.04 with a smooth decline toward the outer regions) and α-enriched ([α/Fe] = 0.4 ± 0.1). This suggests a very short formation time scale for the bulk of the stars in this galaxy. This object also rotates very fast (V {sub rot} ∼ 300 km s{sup –1}) and has a large central velocity dispersion (σ > 300 km s{sup –1}). NGC 1277 allows the exploration in full detail of properties such as the structure, internal dynamics, metallicity, and initial mass function as they were at ∼10-12 Gyr ago when the first massive galaxies were built.

  18. A NuSTAR Survey of Nearby Ultraluminous Infrared Galaxies

    Science.gov (United States)

    Teng, Stacy H.; Rigby, Jane R.; Stern, Daniel; Ptak, Andrew; Alexander, D. M.; Bauer, Franz E.; Boggs, Stephen E.; Brandt, W. Niel; Christensen, Finn E.; Comastri, Andrea; Craig, William W.; Farrah, Duncan; Gandhi, Poshak; Hailey, Charles J.; Harrison, Fiona A.; Hickox, Ryan C.; Koss, Michael; Luo, Bin; Treister, Ezequiel; Zhang, William W.

    2015-11-01

    We present a Nuclear Spectroscopic Telescope Array (NuSTAR), Chandra, and XMM-Newton survey of nine of the nearest ultraluminous infrared galaxies (ULIRGs). The unprecedented sensitivity of NuSTAR at energies above 10 keV enables spectral modeling with far better precision than was previously possible. Six of the nine sources observed were detected sufficiently well by NuSTAR to model in detail their broadband X-ray spectra, and recover the levels of obscuration and intrinsic X-ray luminosities. Only one source (IRAS 13120-5453) has a spectrum consistent with a Compton-thick active galactic nucleus (AGN), but we cannot rule out that a second source (Arp 220) harbors an extremely highly obscured AGN as well. Variability in column density (reduction by a factor of a few compared to older observations) is seen in IRAS 05189-2524 and Mrk 273, altering the classification of these borderline sources from Compton-thick to Compton-thin. The ULIRGs in our sample have surprisingly low observed fluxes in high-energy (>10 keV) X-rays, especially compared to their bolometric luminosities. They have lower ratios of unabsorbed 2-10 keV to bolometric luminosity, and unabsorbed 2-10 keV to mid-IR [O iv] line luminosity than do Seyfert 1 galaxies. We identify IRAS 08572+3915 as another candidate intrinsically X-ray weak source, similar to Mrk 231. We speculate that the X-ray weakness of IRAS 08572+3915 is related to its powerful outflow observed at other wavelengths.

  19. A NuSTAR SURVEY OF NEARBY ULTRALUMINOUS INFRARED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Stacy H.; Rigby, Jane R.; Ptak, Andrew [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Alexander, D. M. [Department of Physics, Durham University, Durham, DH1 3LE (United Kingdom); Bauer, Franz E. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 306, Santiago 22 (Chile); Boggs, Stephen E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Brandt, W. Niel; Luo, Bin [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Christensen, Finn E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Comastri, Andrea [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Farrah, Duncan [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Gandhi, Poshak [School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ (United Kingdom); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Hickox, Ryan C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Koss, Michael [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); and others

    2015-11-20

    We present a Nuclear Spectroscopic Telescope Array (NuSTAR), Chandra, and XMM-Newton survey of nine of the nearest ultraluminous infrared galaxies (ULIRGs). The unprecedented sensitivity of NuSTAR at energies above 10 keV enables spectral modeling with far better precision than was previously possible. Six of the nine sources observed were detected sufficiently well by NuSTAR to model in detail their broadband X-ray spectra, and recover the levels of obscuration and intrinsic X-ray luminosities. Only one source (IRAS 13120–5453) has a spectrum consistent with a Compton-thick active galactic nucleus (AGN), but we cannot rule out that a second source (Arp 220) harbors an extremely highly obscured AGN as well. Variability in column density (reduction by a factor of a few compared to older observations) is seen in IRAS 05189–2524 and Mrk 273, altering the classification of these borderline sources from Compton-thick to Compton-thin. The ULIRGs in our sample have surprisingly low observed fluxes in high-energy (>10 keV) X-rays, especially compared to their bolometric luminosities. They have lower ratios of unabsorbed 2–10 keV to bolometric luminosity, and unabsorbed 2–10 keV to mid-IR [O iv] line luminosity than do Seyfert 1 galaxies. We identify IRAS 08572+3915 as another candidate intrinsically X-ray weak source, similar to Mrk 231. We speculate that the X-ray weakness of IRAS 08572+3915 is related to its powerful outflow observed at other wavelengths.

  20. Dust evolution processes constrained by extinction curves in nearby galaxies

    CERN Document Server

    Hou, Kuan-Chou; Michałowski, Michał J

    2016-01-01

    Extinction curves, especially those in the Milky Way (MW), the Large Magellanic Cloud (LMC), and the Small Magellanic Cloud (SMC), have provided us with a clue to the dust properties in the nearby Universe. We examine whether or not these extinction curves can be explained by well known dust evolution processes. We treat the dust production in stellar ejecta, destruction in supernova shocks, dust growth by accretion and coagulation, and dust disruption by shattering. To make a survey of the large parameter space possible, we simplify the treatment of the grain size distribution evolution by adopting the `two-size approximation', in which we divide the grain population into small ($\\lesssim 0.03~\\mu$m) and large ($\\gtrsim 0.03~\\mu$m) grains. It is confirmed that the MW extinction curve can be reproduced in reasonable ranges for the time-scale of the above processes with a silicate-graphite mixture. This indicates that the MW extinction curve is a natural consequence of the dust evolution through the above proc...

  1. A NuSTAR Survey of Nearby Ultraluminous Infrared Galaxies

    CERN Document Server

    Teng, Stacy H; Stern, Daniel; Ptak, Andrew; Alexander, D M; Bauer, Franz E; Boggs, Stephen E; Brandt, W Niel; Christensen, Finn E; Comastri, Andrea; Craig, William W; Farrah, Duncan; Gandhi, Poshak; Hailey, Charles J; Harrison, Fiona A; Hickox, Ryan C; Koss, Michael; Luo, Bin; Treister, Ezequiel; Zhang, William W

    2015-01-01

    We present a NuSTAR, Chandra, and XMM--Newton survey of nine of the nearest ultraluminous infrared galaxies (ULIRGs). The unprecedented sensitivity of NuSTAR at energies above 10 keV enables spectral modeling with far better precision than was previously possible. Six of the nine sources observed were detected sufficiently well by NuSTAR to model in detail their broadband X-ray spectra, and recover the levels of obscuration and intrinsic X-ray luminosities. Only one source (IRAS 13120--5453) has a spectrum consistent with a Compton--thick AGN, but we cannot rule out that a second source (Arp 220) harbors an extremely highly obscured AGN as well. Variability in column density (reduction by a factor of a few compared to older observations) is seen in IRAS 05189--2524 and Mrk 273, altering the classification of these border-line sources from Compton-thick to Compton-thin. The ULIRGs in our sample have surprisingly low observed fluxes in high energy (>10 keV) X-rays, especially compared to their bolometric lumino...

  2. Dust evolution processes constrained by extinction curves in nearby galaxies

    Science.gov (United States)

    Hou, Kuan-Chou; Hirashita, Hiroyuki; Michałowski, Michał J.

    2016-09-01

    Extinction curves, especially those in the Milky Way (MW), the Large Magellanic Cloud (LMC), and the Small Magellanic Cloud (SMC), have provided us with a clue to the dust properties in the nearby Universe. We examine whether or not these extinction curves can be explained by well-known dust evolution processes. We treat the dust production in stellar ejecta, destruction in supernova shocks, dust growth by accretion and coagulation, and dust disruption by shattering. To make a survey of the large parameter space possible, we simplify the treatment of the grain size distribution evolution by adopting the "two-size approximation," in which we divide the grain population into small (≲0.03 μm) and large (≳0.03 μm) grains. It is confirmed that the MW extinction curve can be reproduced in reasonable ranges for the time-scale of the above processes with a silicate-graphite mixture. This indicates that the MW extinction curve is a natural consequence of the dust evolution through the above processes. We also find that the same models fail to reproduce the SMC/LMC extinction curves. Nevertheless, this failure can be remedied by giving higher supernova destruction rates for small dust particles dust and considering amorphous carbon for carbonaceous dust; these modifications in fact fall in line with previous studies. Therefore, we conclude that the current dust evolution scenario composed of the aforementioned processes is successful in explaining the extinction curves. All the extinction curves favor efficient interstellar processing of dust, especially strong grain growth by accretion and coagulation.

  3. Large-scale HI in nearby radio galaxies : segregation in neutral gas content with radio source size

    NARCIS (Netherlands)

    Emonts, B. H. C.; Morganti, R.; Oosterloo, T. A.; van der Hulst, J. M.; van Moorsel, G.; Tadhunter, C. N.

    2007-01-01

    We present results of a study of neutral hydrogen ( HI) in a complete sample of nearby non-cluster radio galaxies. We find that radio galaxies with large amounts of extended HI (M-HI >= 109 M-circle dot) all have a compact radio source. The host galaxies of the more extended radio sources, all of Fa

  4. Host Galaxies of Type Ia Supernovae from the Nearby Supernova Factory

    CERN Document Server

    Childress, M J; Antilogus, P; Aragon, C; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Cellier-Holzem, F; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Guy, J; Hsiao, E Y; Kerschhaggl, M; Kim, A G; Kowalski, M; Loken, S; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Runge, K; Scalzo, R; Smadja, G; Tao, C; Thomas, R C; Weaver, B A; Wu, C

    2013-01-01

    We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory (SNfactory). Combining GALEX UV data with optical and near infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star-formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high precision redshifts, gas-phase metallicities, and Halpha-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from SDSS for stellar masses log(M_*/M_Sun)>8.5 where the relation is well-defined. The star-formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, thou...

  5. ALFALFA Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo~P. III. An Extremely Metal Deficient Galaxy

    CERN Document Server

    Skillman, Evan D; Berg, Danielle A; Pogge, Richard W; Haurberg, Nathalie C; Cannon, John M; Aver, Erik; Olive, Keith A; Giovanelli, Riccardo; Haynes, Martha P; Adams, Elizabeth A K; McQuinn, Kristen B W; Rhode, Katherine L

    2013-01-01

    We present KPNO 4-m and LBT/MODS spectroscopic observations of an HII region in the nearby dwarf irregular galaxy Leo P discovered recently in the Arecibo ALFALFA survey. In both observations, we are able to accurately measure the temperature sensitive [O III] 4363 Angstrom line and determine a "direct" oxygen abundance of 12 + log(O/H) = 7.17 +/- 0.04. Thus, Leo P is an extremely metal deficient (XMD) galaxy, and, indeed, one of the most metal deficient star-forming galaxies ever observed. For its estimated luminosity, Leo P is consistent with the relationship between luminosity and oxygen abundance seen in nearby dwarf galaxies. Leo P shows normal alpha element abundance ratios (Ne/O, S/O, and Ar/O) when compared to other XMD galaxies, but elevated N/O, consistent with the "delayed release" hypothesis for N/O abundances. We derive a helium mass fraction of 0.2509 +0.0184 -0.0123 which compares well with the WMAP + BBN prediction of 0.2483 +/- 0.0002 for the primordial helium abundance. We suggest that surve...

  6. The host galaxy/AGN connection in nearby early-type galaxies. Is there a miniature radio-galaxy in every "core" galaxy?

    CERN Document Server

    Balmaverde, B

    2005-01-01

    This is the second of a series of three papers exploring the connection between the multiwavelength properties of AGN in nearby early-type galaxies and the characteristics of their hosts. In Capetti et al. (2005) we presented a study of the surface brightness profiles for the 65 objects with available archival HST images out of the 116 radio-detected galaxies. We classified early-type galaxies into ``core'' and ``power-law'' galaxies, discriminating on the basis of the slope of their nuclear brightness profiles. Here we focus on the 29 core galaxies (hereafter CoreG). We used HST and Chandra data to isolate their nuclear emission. The CoreG invariably host radio-loud nuclei, with an average radio-loudness parameter of Log R = 3.6. The optical and X-ray nuclear luminosities correlate with the radio-core power, smoothly extending the analogous correlations already found for low luminosity radio-galaxies. This supports the interpretation of a common non-thermal origin of the nuclear emission also for CoreG. The ...

  7. The nearby Galaxy structure toward the Vela Gum nebula

    Science.gov (United States)

    Giorgi, E. E.; Solivella, G. R.; Perren, G. I.; Vázquez, R. A.

    2015-10-01

    We report on UBVI photometry and spectroscopy for MK classification purposes carried out in the fields of five open clusters projected against the Vela Gum in the Third Galactic Quadrant of the Galaxy. They are Ruprecht 20, Ruprecht 47, Ruprecht 60, NGC 2660 and NGC 2910. We could improve/confirm the parameters of these objects derived before. Ruprecht 20 is not a real physical entity, in agreement with earlier suggestions. Ruprecht 47, a young cluster in the Galactic plane, at 4.4 kpc from the Sun is quite farther than in previous distance estimations and becomes, therefore, a member of the Puppis OB2 association. For the first time Ruprecht 60 was surveyed in UBVI photometry. We found it to be placed at 4.2 kpc from the Sun of about and 1 Gyr old. NGC 2660 is another old object in our survey for which distance and age are coincident with previous findings. NGC 2910 turns out to be a young cluster of Vela OB1 association at a distance of 1.4 kpc approximately and 60 Myr old. The spectroscopic parallax method has been applied to several stars located in the fields of four out of the five clusters to get their distances and reddenings. With this method we found two blue stars in the field of NGC 2910 at distances that make them likely members of Vela OB1 too. Also, projected against the fields of Ruprecht 20 and Ruprecht 47 we have detected other young stars favoring not only the existence of Puppis OB1 and OB2 but conforming a young stellar group at ∼ 1 kpc from the Sun and extending for more than 6 kpc outward the Galaxy. If this is the case, there is a thickening of the thin Galactic disk of more than 300 pc at just 2-3 kpc from the Sun. Ruprecht 60 and NGC 2660 are too old objects that have no physical relation with the associations under discussion. An astonishing result has been the detection in the background of Ruprecht 47 of a young star at the impressive distance of 9.5 kpc from the Sun that could be a member of the innermost part of the Outer Arm

  8. Cool dust heating and temperature mixing in nearby star-forming galaxies

    CERN Document Server

    Hunt, L K; Bianchi, S; Gordon, K D; Aniano, G; Calzetti, D; Dale, D A; Helou, G; Hinz, J L; Kennicutt, R C; Roussel, H; Wilson, C D; Bolatto, A; Boquien, M; Croxall, K V; Galametz, M; de Paz, A Gil; Koda, J; Munoz-Mateos, J C; Sandstrom, K M; Sauvage, M; Vigroux, L; Zibetti, S

    2014-01-01

    Physical conditions of the interstellar medium in galaxies are closely linked to the ambient radiation field and the heating of dust grains. In order to characterize dust properties in galaxies over a wide range of physical conditions, we present here the radial surface brightness profiles of the entire sample of 61 galaxies from Key Insights into Nearby Galaxies: Far-Infrared Survey with Herschel (KINGFISH). The main goal of our work is the characterization of the grain emissivities, dust temperatures, and interstellar radiation fields responsible for heating the dust. After fitting the dust and stellar radial profiles with exponential functions, we fit the far-infrared spectral energy distribution (SED) in each annular region with single-temperature modified black bodies using both variable (MBBV) and fixed (MBBF) emissivity indices beta, as well as with physically motivated dust models. Results show that while most SED parameters decrease with radius, the emissivity index beta also decreases with radius in...

  9. Structure, dynamical impact and origin of magnetic fields in nearby galaxies in the SKA era

    CERN Document Server

    Beck, Rainer; Colafrancesco, Sergio; Dettmar, Ralf-Jürgen; Ferrière, Katia; Fletcher, Andrew; Heald, George; Heesen, Volker; Horellou, Cathy; Krause, Marita; Lou, Yu-Qing; Mao, Sui Ann; Paladino, Rosita; Schinnerer, Eva; Sokoloff, Dmitry; Stil, Jeroen; Tabatabaei, Fatemeh

    2015-01-01

    Magnetic fields are an important ingredient of the interstellar medium (ISM). Besides their importance for star formation, they govern the transport of cosmic rays, relevant to the launch and regulation of galactic outflows and winds, which in turn are pivotal in shaping the structure of halo magnetic fields. Mapping the small-scale structure of interstellar magnetic fields in many nearby galaxies is crucial to understand the interaction between gas and magnetic fields, in particular how gas flows are affected. Elucidation of the magnetic role in, e.g., triggering star formation, forming and stabilising spiral arms, driving outflows, gas heating by reconnection and magnetising the intergalactic medium has the potential to revolutionise our physical picture of the ISM and galaxy evolution in general. Radio polarisation observations in the very nearest galaxies at high frequencies (>= 3 GHz) and with high spatial resolution (<= 5") hold the key here. The galaxy survey with SKA1 that we propose will also be a...

  10. Booms and Busts: the Burstiness of Star Formation in Nearby Dwarf Galaxies

    CERN Document Server

    Cole, Andrew A

    2009-01-01

    In this review I summarise recent advances in our understanding of the importance of starburst events to the evolutionary histories of nearby galaxies. Ongoing bursts are easily diagnosed in emission-line surveys, but assessing the timing and intensity of fossil bursts requires more effort, usually demanding color-magnitude diagrams or spectroscopy of individual stars. For ages older than ~1 Gyr, this type of observation is currently limited to the Local Group and its immediate surroundings. However, if the Local Volume is representative of the Universe as a whole, then studies of the age and metallicity distributions of star clusters and resolved stellar populations should give statistical clues as to the frequency and importance of bursts to the histories of galaxies in general. Based on starburst statistics in the literature and synthetic colour-magnitude diagram studies of Local Group galaxies, I attempt to distinguish between systemic starbursts that strongly impact galaxy evolution and stochastic bursts...

  11. AN INFRARED CENSUS OF DUST IN NEARBY GALAXIES WITH SPITZER (DUSTINGS). I. OVERVIEW

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Martha L.; Sonneborn, George [Observational Cosmology Laboratory, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); McQuinn, Kristen B. W.; Gehrz, Robert D.; Skillman, Evan [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street SE, University of Minnesota, Minneapolis, MN 55455 (United States); Barmby, Pauline [Department of Physics and Astronomy, University of Western Ontario, London, ON, N6A 3K7 (Canada); Bonanos, Alceste Z. [IAASARS, National Observatory of Athens, GR-15236 Penteli (Greece); Gordon, Karl D.; Meixner, Margaret [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Groenewegen, M. A. T. [Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels (Belgium); Lagadec, Eric [Laboratoire Lagrange, UMR7293, Univ. Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d' Azur, F-06300 Nice (France); Lennon, Daniel [ESA—European Space Astronomy Centre, Apdo. de Correo 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Marengo, Massimo [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Sloan, G. C. [Astronomy Department, Cornell University, Ithaca, NY 14853-6801 (United States); Van Loon, Jacco Th. [Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG (United Kingdom); Zijlstra, Albert, E-mail: martha.boyer@nasa.gov [Jodrell Bank Centre for Astrophysics, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom)

    2015-01-01

    Nearby resolved dwarf galaxies provide excellent opportunities for studying the dust-producing late stages of stellar evolution over a wide range of metallicity (–2.7 ≲ [Fe/H] ≲ –1.0). Here, we describe DUSTiNGS (DUST in Nearby Galaxies with Spitzer): a 3.6 and 4.5 μm post-cryogen Spitzer Space Telescope imaging survey of 50 dwarf galaxies within 1.5 Mpc that is designed to identify dust-producing asymptotic giant branch (AGB) stars and massive stars. The survey includes 37 dwarf spheroidal, 8 dwarf irregular, and 5 transition-type galaxies. This near-complete sample allows for the building of statistics on these rare phases of stellar evolution over the full metallicity range. The photometry is >75% complete at the tip of the red giant branch for all targeted galaxies, with the exception of the crowded inner regions of IC 10, NGC 185, and NGC 147. This photometric depth ensures that the majority of the dust-producing stars, including the thermally pulsing AGB stars, are detected in each galaxy. The images map each galaxy to at least twice the half-light radius to ensure that the entire evolved star population is included and to facilitate the statistical subtraction of background and foreground contamination, which is severe at these wavelengths. In this overview, we describe the survey, the data products, and preliminary results. We show evidence for the presence of dust-producing AGB stars in eight of the targeted galaxies, with metallicities as low as [Fe/H] = –1.9, suggesting that dust production occurs even at low metallicity.

  12. Hubble Residuals of Nearby SN Ia Are Correlated with Host Galaxy Masses

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Patrick L.; /KIPAC, Menlo Park /SLAC; Hicken, Malcolm; /Harvard-Smithsonian Ctr. Astrophys.; Burke, David L.; /KIPAC, Menlo Park /SLAC; Mandel, Kaisey S.; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2010-05-03

    From Sloan Digital Sky Survey u{prime} g{prime} r{prime} i{prime} z{prime} imaging, we estimate the stellar masses of the host galaxies of 70 low redshift SN Ia (0.015 < z < 0.08) from the hosts absolute luminosities and mass-to-light ratios. These nearby SN were discovered largely by searches targeting luminous galaxies, and we find that their host galaxies are substantially more massive than the hosts of SN discovered by the flux-limited Supernova Legacy Survey. Testing four separate light curve fitters, we detect {approx}2.5{sigma} correlations of Hubble residuals with both host galaxy size and stellar mass, such that SN Ia occurring in physically larger, more massive hosts are {approx}10% brighter after light curve correction. The Hubble residual is the deviation of the inferred distance modulus to the SN, calculated from its apparent luminosity and light curve properties, away from the expected value at the SN redshift. Marginalizing over linear trends in Hubble residuals with light curve parameters shows that the correlations cannot be attributed to a light curve-dependent calibration error. Combining 180 higher-redshift ESSENCE, SNLS, and HigherZ SN with 30 nearby SN whose host masses are less than 10{sup 10.8} M{circle_dot} n a cosmology fit yields 1 + w = 0.22{sub -0.108}{sup +0.152}, while a combination where the 30 nearby SN instead have host masses greater than 10{sup 10.8} M{circle_dot} yields 1 + w = ?0.03{sub -0.143}{sup +0.217}. Progenitor metallicity, stellar population age, and dust extinction correlate with galaxy mass and may be responsible for these systematic effects. Host galaxy measurements will yield improved distances to SN Ia.

  13. Star Formation in Dwarf Galaxies of the Nearby Centaurus A Group

    CERN Document Server

    Cote, Stephanie; Skillman, Evan D; Miller, Bryan W

    2009-01-01

    We present Halpha narrow-band imaging of 17 dwarf irregular galaxies (dIs) in the nearby Centaurus A Group. Although all large galaxies of the group have a current or recent enhanced star formation episode, the dIs have normal star formation rates and do not contain a larger fraction of dwarf starbursts than other nearby groups. Relative distances between dIs and larger galaxies of the group can be computed in 3D since most of them have now fairly accurately known distances. We find that the dI star formation rates do not depend on local environment, and in particular they do not show any correlation with the distance of the dI to the nearest large galaxy of the group. There is a clear morphology-density relation in the Centaurus A Group, similarly to the Sculptor and Local Groups, in the sense that dEs/dSphs tend to be at small distances from the more massive galaxies of the group, while dIs are on average at larger distances. We find four transition dwarfs in the Group, dwarfs that show characteristics of b...

  14. HERSCHEL FAR-INFRARED AND SUBMILLIMETER PHOTOMETRY FOR THE KINGFISH SAMPLE OF NEARBY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Dale, D. A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Aniano, G.; Draine, B. T. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Engelbracht, C. W.; Hinz, J. L.; Montiel, E. J. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Krause, O.; Groves, B. A. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Roussel, H. [Institut d' Astrophysique de Paris, UMR7095 CNRS, Universite Pierre and Marie Curie, 98 bis Boulevard Arago, 75014 Paris (France); Appleton, P. N. [NASA Herschel Science Center, IPAC, California Institute of Technology, Pasadena, CA 91125 (United States); Armus, L.; Beirao, P. [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States); Bolatto, A. D. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Brandl, B. R. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Calzetti, D.; Crocker, A. F. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Croxall, K. V. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Galametz, M. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Gordon, K. D. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Hao, C.-N., E-mail: ddale@uwyo.edu [Tianjin Astrophysics Center, Tianjin Normal University, Tianjin 300387 (China); and others

    2012-01-20

    New far-infrared and submillimeter photometry from the Herschel Space Observatory is presented for 61 nearby galaxies from the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) sample. The spatially integrated fluxes are largely consistent with expectations based on Spitzer far-infrared photometry and extrapolations to longer wavelengths using popular dust emission models. Dwarf irregular galaxies are notable exceptions, as already noted by other authors, as their 500 {mu}m emission shows evidence for a submillimeter excess. In addition, the fraction of dust heating attributed to intense radiation fields associated with photodissociation regions is found to be (21 {+-} 4)% larger when Herschel data are included in the analysis. Dust masses obtained from the dust emission models of Draine and Li are found to be on average nearly a factor of two higher than those based on single-temperature modified blackbodies, as single blackbody curves do not capture the full range of dust temperatures inherent to any galaxy. The discrepancy is largest for galaxies exhibiting the coolest far-infrared colors.

  15. Finding {\\eta} Car Analogs in Nearby Galaxies Using Spitzer: I. Candidate Selection

    CERN Document Server

    Khan, Rubab; Kochanek, C S

    2012-01-01

    The late-stage evolution of the most massive stars such as {\\eta} Carinae is controlled by the effects of mass loss, which may be dominated by poorly understood eruptive mass ejections. Understanding this population is challenging because no true analogs of {\\eta} Car have been clearly identified in the Milky Way or other galaxies. We utilize Spitzer IRAC images of 7 nearby (= 40 M_sun star undergoes such eruptions given our initial results. In Paper II we will characterize the candidates through further analysis and follow-up observations, and there is no barrier to increasing the galaxy sample by an order of magnitude.

  16. The SLUGGS survey: Exploring the metallicity gradients of nearby early-type galaxies to large radii

    CERN Document Server

    Pastorello, Nicola; Foster, Caroline; Brodie, Jean P; Usher, Christopher; Romanowsky, Aaron J; Strader, Jay; Arnold, Jacob A

    2014-01-01

    Stellar metallicity gradients in the outer regions of galaxies are a critical tool for disentangling the contributions of in-situ and ex-situ formed stars. In the two-phase galaxy formation scenario, the initial gas collapse creates steep metallicity gradients, while the accretion of stars formed in satellites tends to flatten these gradients in the outskirts, particularly for massive galaxies. This work presents the first compilation of extended metallicity profiles over a wide range of galaxy mass. We use the DEIMOS spectrograph on the Keck telescope in multi-slit mode to obtain radial stellar metallicity profiles for 22 nearby early-type galaxies. From the calcium triplet lines in the near-infrared we measure the metallicity of the starlight up to 3 effective radii. We find a relation between the outer metallicity gradient and galaxy mass, in the sense that lower mass systems show steeper metallicity gradients than more massive galaxies. This result is consistent with a picture in which the ratio of ex-sit...

  17. The radio properties of a complete, X-ray selected sample of nearby, massive elliptical galaxies

    CERN Document Server

    Dunn, Robert; Taylor, Greg; Shurkin, Kathleen; Gentile, Gianfranco; Fabian, Andy; Reynolds, Chris

    2010-01-01

    We investigate the radio properties of a complete sample of nearby, massive, X-ray bright elliptical and S0 galaxies. Our sample contains 18 galaxies with ROSAT All-Sky Survey X-ray fluxes Fx_(0.1-2.4 keV) > 3 x 10^(-12) erg/s/cm^2, within a distance of 100 Mpc. For these galaxies, we have complete (18/18) VLA radio and Chandra X-ray coverage. Nuclear radio emission is detected from 17/18 of the galaxies. Ten of the galaxies exhibit extended radio emission; of these ten, all but one also exhibit clear evidence of interaction of the radio source with the surrounding, X-ray emitting gas. Among the seven galaxies with unresolved radio sources, one has clear, and one has small, cavity-like features in the Chandra X-ray images; a third has a disturbed X-ray morphology. Using a radio luminosity limit equivalent to L_(1.4 Ghz) > 10^(23) W/Hz to calculate the radio-loud fraction, we find that this misses the majority of the radio detected galaxies in the sample. We determine integrated radio-to-X-ray flux ratios for ...

  18. SKA studies of nearby galaxies: star-formation, accretion processes and molecular gas across all environments

    CERN Document Server

    Beswick, R J; Perez-Torres, M A; Richards, A M S; Aalto, S; Alberdi, A; Argo, M K; van Bemmel, I; Conway, J E; Dickinson, C; Fenech, D M; Gray, M D; Klockner, H-R; Murphy, E J; Muxlow, T W B; Peel, M; Rushton, A P; Schinnerer, E

    2014-01-01

    The SKA will be a transformational instrument in the study of our local Universe. In particular, by virtue of its high sensitivity (both to point sources and diffuse low surface brightness emission), angular resolution and the frequency ranges covered, the SKA will undertake a very wide range of astrophysical research in the field of nearby galaxies. By surveying vast numbers of nearby galaxies of all types with $\\mu$Jy sensitivity and sub-arcsecond angular resolutions at radio wavelengths, the SKA will provide the cornerstone of our understanding of star-formation and accretion activity in the local Universe. In this chapter we outline the key continuum and molecular line science areas where the SKA, both during phase-1 and when it becomes the full SKA, will have a significant scientific impact.

  19. Theoretical Explanation of the Cosmic Ray Perpendicular Diffusion Coefficient in the Nearby Starburst Galaxy NGC 253

    OpenAIRE

    Buffie, Kaitlynn; Heesen, Volker; Shalchi, Andreas

    2012-01-01

    Diffusion coefficients are usually used to describe the propagation of Cosmic Rays through the Universe. Whereas such transport parameters can be obtained from experiments in the Solar System, it is difficult to determine diffusion coefficients in the Milky Way or in external galaxies. Recently a value for the perpendicular diffusion coefficient in the nearby starburst halaxy NGC 253 has been proposed. In the present paper we reproduce this value theoretically by using an advanced analytical ...

  20. From Nearby Low Luminosity AGN to High Redshift Radio Galaxies: Science Interests with SKA

    CERN Document Server

    Kharb, P; Singh, V; Bagchi, J; Chandra, C H Ishwara; Hota, A; Konar, C; Wadadekar, Y; Shastri, P; Das, M; Baliyan, K; Nath, B B; Pandey-Pommier, M

    2016-01-01

    We present detailed science cases that a large fraction of the Indian AGN community is interested in pursuing with the upcoming Square Kilometre Array (SKA). These interests range from understanding low luminosity active galactic nuclei in the nearby Universe to powerful radio galaxies at high redshifts. Important unresolved science questions in AGN physics are discussed. Ongoing low-frequency surveys with the SKA pathfinder telescope GMRT, are highlighted.

  1. Resolving the extended stellar halos of nearby galaxies: the wide-field PISCeS survey

    CERN Document Server

    Crnojević, D; Caldwell, N; Guhathakurta, P; McLeod, B; Seth, A; Simon, J D; Strader, J; Toloba, E

    2015-01-01

    In the wide-field Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), we investigate the resolved stellar halos of two nearby galaxies (the elliptical Centaurus A and the spiral Sculptor, D $\\sim3.7$ Mpc) out to a projected galactocentric radius of 150 kpc with Magellan/Megacam. The survey has led to the discovery of $\\sim$20 faint satellites to date, plus prominent streams and substructures in two environments that are substantially different from the Local Group, i.e. the Centaurus A group dominated by an elliptical and the loose Sculptor group of galaxies. These discoveries clearly attest to the importance of past and ongoing accretion processes in shaping the halos of these nearby galaxies, and provide the first census of their satellite systems down to an unprecedented $M_V<-8$. The detailed characterization of the stellar content, shape and gradients in the extended halos of Sculptor, Centaurus A, and their dwarf satellites provides key constraints on theoretical models of galaxy formation a...

  2. Resolving the extended stellar halos of nearby galaxies: the wide-field PISCeS survey†

    Science.gov (United States)

    Crnojević, D.; Sand, D. J.; Caldwell, N.; Guhathakurta, P.; McLeod, B.; Seth, A.; Simon, J. D.; Strader, J.; Toloba, E.

    2016-08-01

    In the wide-field Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), we investigate the resolved stellar halos of two nearby galaxies (the elliptical Centaurus A and the spiral Sculptor, D ~ 3.7 Mpc) out to a projected galactocentric radius of 150 kpc with Magellan/Megacam. The survey has led to the discovery of ~20 faint satellites to date, plus prominent streams and substructures in two environments that are substantially different from the Local Group, i.e. the Centaurus A group dominated by an elliptical and the loose Sculptor group of galaxies. These discoveries clearly attest to the importance of past and ongoing accretion processes in shaping the halos of these nearby galaxies, and provide the first census of their satellite systems down to an unprecedented MV < -8. The detailed characterization of the stellar content, shape and gradients in the extended halos of Sculptor, Centaurus A, and their dwarf satellites provides key constraints on theoretical models of galaxy formation and evolution.

  3. X-ray and Ultraviolet Properties of AGN in Nearby Dwarf Galaxies

    CERN Document Server

    Baldassare, Vivienne F; Gallo, Elena; Greene, Jenny E

    2016-01-01

    We present new Chandra X-ray Observatory and Hubble Space Telescope observations of eight optically selected broad-line AGN candidates in nearby dwarf galaxies ($z<0.055$). Including archival Chandra observations of three additional sources, our sample contains all ten galaxies from Reines et al. (2013) with both broad H$\\alpha$ emission and narrow-line AGN ratios (6 AGNs, 4 Composites), as well as one low-metallicity dwarf galaxy with broad H$\\alpha$ and narrow-line ratios characteristic of star formation. All eleven galaxies are detected in X-rays. Nuclear X-ray luminosities range from $L_{0.5-7 \\rm{keV}}\\approx5\\times10^{39}$ to $1\\times10^{42}$ $\\rm{erg}\\rm{s^{-1}}$. In all cases except for the star forming galaxy, the nuclear X-ray luminosities are significantly higher than would be expected from X-ray binaries, providing strong confirmation that AGN and composite dwarf galaxies do indeed host actively accreting BHs. Using our estimated BH masses (which range from $\\sim7\\times10^{4}-1\\times10^{6}~M_{\\...

  4. Observational Constraints on the Molecular Gas Content in Nearby Starburst Dwarf Galaxies

    CERN Document Server

    McQuinn, Kristen B W; Dalcanton, Julianne J; Dolphin, Andrew E; Cannon, John M; Holtzman, Jon; Weisz, Daniel R; Williams, Benjamin F

    2012-01-01

    Using star formation histories derived from optically resolved stellar populations in nineteen nearby starburst dwarf galaxies observed with the Hubble Space Telescope, we measure the stellar mass surface densities of stars newly formed in the bursts. By assuming a star formation efficiency (SFE), we then calculate the inferred gas surface densities present at the onset of the starbursts. Assuming a SFE of 1%, as is often assumed in normal star-forming galaxies, and assuming that the gas was purely atomic, translates to very high HI surface densities (~10^2-10^3 Msun pc^-2), which are much higher than have been observed in dwarf galaxies. This implies either higher values of SFE in these dwarf starburst galaxies or the presence of significant amounts of H_2 in dwarfs (or both). Raising the assumed SFEs to 10% or greater (in line with observations of more massive starbursts associated with merging galaxies), still results in HI surface densities higher than observed in 10 galaxies. Thus, these observations app...

  5. An atlas of Hubble space telescope ultraviolet images of nearby galaxies

    CERN Document Server

    Maoz, D; Ho, L C; Macchetto, F D; Rix, H W; Schneider, D P; Maoz, Dan; Filippenko, Alexei V; Ho, Luis C; Macchetto, F Duccio; Rix, Hans Walter; Schneider, Donald P

    1996-01-01

    We present an atlas of UV (\\sim 2300 \\AA) images, obtained with the Hubble Space Telescope (HST) Faint Object Camera, of the central 22''\\times 22'' of 110 galaxies. The observed galaxies are an unbiased selection constituting about one half of a complete sample of all large (D>6') and nearby (V< 2000 km s^{-1}) galaxies. This is the first extensive UV imaging survey of normal galaxies. The data are useful for studying star formation, low-level nuclear activity, and UV emission by evolved stellar populations in galaxies. At the HST resolution (\\sim 0.05''), the images display an assortment of morphologies and UV brightnesses. These include bright nuclear point sources, compact young star clusters scattered in the field or arranged in circumnuclear rings, centrally-peaked diffuse light distributions, and galaxies with weak or undetected UV emission. We measure the integrated \\sim 2300 \\AA\\ flux in each image, classify the UV morphology, and examine trends between these parameters and the optical properties ...

  6. Extraplanar diffuse ionized gas in a small sample of nearby edge-on galaxies

    CERN Document Server

    Rossa, J

    2000-01-01

    We present narrowband H-alpha imaging data of a small survey of nearby edge-on spiral galaxies, aiming at the detection of `extraplanar' diffuse ionized gas (DIG). A few of our studied edge-on spirals show signs of disk-halo interaction (DHI), where extended line emission far above the galactic plane of these galaxies is detected. In some cases an extraplanar diffuse ionized gas (eDIG) layer is discovered, e.g., NGC4634, NGC 3044, while other galaxies show only filamentary features reaching into the halo (e.g., IC 2531) and some galaxies show no sign of eDIG at all. The extraplanar distances of the DIG layer in our narrowband H-alpha images reach values of z<= 2 kpc above the galactic plane. The derived star formation rates (SFRs) from the H-alpha flux of the studied galaxies range from 0.05-0.7 M_{sun}/yr, neglecting a correction for internal absorption. The variation of the SFR values among our sample galaxies reflects the diversity of star formation within this sample. A diagnostic diagram is introduced...

  7. The interstellar medium and star formation in nearby galaxies. Ludwig Biermann Award Lecture 2013

    Science.gov (United States)

    Bigiel, F.; Cormier, D.; Schmidt, T.

    In this overview article we present some of the key projects we pursue in our Emmy Noether group. Our work is focused on nearby galaxies, where we use multi-wavelength, state-of-the-art survey data to probe distribution, abundance and properties of gas and dust in the interstellar medium (ISM) on [Si II] kpc scales. We study the average, radial distributions of atomic (H I) and molecular hydrogen (H2) across the disks of spiral galaxies and assess local (on 1 kpc scales) correlations between H I, H2 and star formation rate (SFR) surface densities across the inner, optical disks of our sample of [Si II] 30 spiral galaxies. The short H2 depletion times ([Si II] 2 Gyr) we find raises the question of if and how star formation is refueled in galactic disks. We look for such signatures of radial gas flows in our H I data and find compelling evidence at least in one case. We extend and compare our gas-SFR studies to the outer disks of galaxies, where conditions change significantly in the ISM, e.g., low metallicity and dust abundance. We focus on star formation at low-metallicity further with detailed ISM studies in dwarf galaxies, where we combine spectroscopic observations in the infrared with detailed modelling to learn about composition and detailed physical properties of the ISM. Of particular interest is the question of what drives large scale star formation in galaxies at low metallicity.

  8. Gradients of stellar population properties and evolution clues in a nearby galaxy M101

    International Nuclear Information System (INIS)

    Multiband photometric images from ultraviolet and optical to infrared are collected to derive spatially resolved properties of the nearby Scd-type galaxy M101. With evolutionary stellar population synthesis models, two-dimensional distributions and radial profiles of age, metallicity, dust attenuation, and star formation timescale in the form of the Sandage star formation history are obtained. When fitting with the models, we use the IRX-A FUV relation, found to depend on a second parameter of birth rate b (ratio of present- and past-averaged star formation rates), to constrain the dust attenuation. There are obvious parameter gradients in the disk of M101, which supports the theory of an 'inside-out' disk growth scenario. Two distinct disk regions with different gradients of age and color are discovered, similar to another late-type galaxy, NGC 628. The metallicity gradient of the stellar content is flatter than that of H II regions. The stellar disk is optically thicker inside than outside and the global dust attenuation of this galaxy is lower compared with galaxies of similar and earlier morphological type. We note that a variational star formation timescale describes the real star formation history of a galaxy. The timescale increases steadily from the center to the outskirt. We also confirm that the bulge in this galaxy is a disk-like pseudobulge, whose evolution is likely to be induced by some secular processes of the small bar which is relatively young, metal-rich, and contains much dust.

  9. What Powers the Compact Radio Emission in Nearby Elliptical and S0 Galaxies?

    CERN Document Server

    Ho, L C

    1999-01-01

    Many nearby early-type (elliptical and S0) galaxies contain weak (milli-Jansky level) nuclear radio sources on scales a few hundred parsecs or less. The origin of the radio emission, however, has remained unclear, especially in volume-limited samples that select intrinsically less luminous galaxies. Both active galactic nuclei and nuclear star formation have been suggested as possible mechanisms for producing the radio emission. This paper utilizes optical spectroscopic information to address this issue. A substantial fraction of the early-type galaxies surveyed with the Very Large Array by Wrobel & Heeschen (1991) exhibits detectable optical emission lines in their nuclei down to very sensitive limits. Comparison of the observed radio continuum power with that expected from the thermal gas traced by the optical emission lines implies that the bulk of the radio emission is nonthermal. Both the incidence and the strength of optical line emission correlate with the radio power. At a fixed line luminosity, e...

  10. A Search for "Dwarf" Seyfert Nuclei. VI. Properties of Emission-Line Nuclei in Nearby Galaxies

    CERN Document Server

    Ho, L C; Sargent, W L W; Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W.

    2003-01-01

    We use the database from Paper III to quantify the global and nuclear properties of emission-line nuclei in the Palomar spectroscopic survey of nearby galaxies. We show that the host galaxies of Seyferts, LINERs, and transition objects share remarkably similar large-scale properties and local environments. The distinguishing traits emerge on nuclear scales. Compared with LINERs, Seyfert nuclei are an order of magnitude more luminous and exhibit higher electron densities and internal extinction. We suggest that Seyfert galaxies possess characteristically more gas-rich circumnuclear regions, and hence a more abundant fuel reservoir and plausibly higher accretion rates. The differences between the ionization state of the narrow emission-line regions of Seyferts and LINERs can be partly explained by the differences in their nebular properties. Transition-type objects are consistent with being composite (LINER/\\hii) systems. With very few exceptions, the stellar population within the central few hundred parsecs of...

  11. Probing the magnetic field of the nearby galaxy pair Arp 269

    CERN Document Server

    Nikiel-Wroczyński, B; Soida, M; Urbanik, M; Knapik, J

    2016-01-01

    We present a multiwavelength radio study of the nearby galaxy pair Arp 269 (NGC 4490/85). High sensitivity to extended structures gained by using the merged interferometric and single- dish maps allowed us to reveal a previously undiscovered extension of the radio continuum emission. Its direction is significantly different from that of the neutral gas tail, suggesting that different physical processes might be involved in their creation. The population of radio- emitting electrons is generally young, signifying an ongoing, vigorous star formation -- this claim is supported by strong magnetic fields (over 20 {\\mu}G), similar to the ones found in much larger spiral galaxies. From the study of the spectral energy distribution, we conclude that the electron population in the intergalactic bridge between member galaxies originates from the disc areas, and therefore its age (approximately 3.7--16.9 Myr, depending on the model used) reflects the time-scale of the interaction. We have also discovered an angularly ne...

  12. HST/ACS Lyman alpha imaging of the nearby starburst ESO338-IG04

    CERN Document Server

    Hayes, M; Mas-Hesse, J M; Kunth, D; Leitherer, C; Petrosian, A

    2005-01-01

    ESO338-IG04 is a well known, local, luminous Blue Compact Galaxy. It has a complex morphology and contains a central young starburst with compact young star clusters. The galaxy was imaged using HST/ACS in the Lyman alpha line and continuum. Using the Starburst99 synthetic spectra and other imaging data from HST/WFPC2 we developed a technique that allows us to make the first photometrically valid continuum subtraction for the LYa line. Our results are in qualitative agreement with the models of LYa escape being regulated by kinematical properties of the interstellar medium. The line-only image shows LYa in both emission and absorption. Notably, emission is seen from central bright young clusters and is in spatial agreement with the features present in a longslit spectrum taken with HST/STIS. Diffuse LYa emission regions are seen surrounding the central starburst where photons escape after one or more resonant scatterings in HI. These regions dominate the total LYa output. Photometry reveals a total LYa flux o...

  13. Galaxy evolution in nearby galaxy groups. III. A GALEX view of NGC 5846, the largest group in the local universe

    CERN Document Server

    Marino, Antonietta; Rampazzo, Roberto; Bianchi, Luciana

    2016-01-01

    We explore the co-evolution of galaxies in nearby groups (V < 3000 km/s) with a multi-wavelength approach. We analyze GALEX far-UV (FUV) and near-UV (NUV) imaging and SDSS u,g,r,i,z data of groups spanning a large range of dynamical phases. We characterize the photometric properties of spectroscopically-confirmed galaxy members and investigate the global properties of the groups through a dynamical analysis. Here we focus on NGC 5846, the third most massive association of Early-Type Galaxies (ETG) after the Virgo and Fornax clusters. The group, composed of 90 members, is dominated by ETGs (about 80 per cent), and among ETGs about 40\\% are dwarfs. Results are compared with those obtained for three groups in the LeoII cloud, which are radically different both in member-galaxy population and dynamical properties. The FUV-NUV cumulative colour distribution and the normalized UV luminosity function (LF) significantly differ due to the different fraction of late-type galaxy population. The UV LF of NGC 5846 rese...

  14. The JCMT Nearby Galaxies Legacy Survey IV. Velocity Dispersions in the Molecular Interstellar Medium in Spiral Galaxies

    CERN Document Server

    Wilson, C D; Irwin, J; Knapen, J H; Israel, F P; Serjeant, S; Attewell, D; Bendo, G J; Brinks, E; Butner, H M; Clements, D L; Leech, J; Matthews, H E; Muehle, S; Mortier, A M J; Parkin, T J; Petitpas, G; Tan, B K; Tilanus, R P J; Usero, A; Vaccari, M; van der Werf, P; Wiegert, T; Zhu, M

    2010-01-01

    An analysis of large-area CO J=3-2 maps from the James Clerk Maxwell Telescope for 12 nearby spiral galaxies reveals low velocity dispersions in the molecular component of the interstellar medium. The three lowest luminosity galaxies show a relatively flat velocity dispersion as a function of radius while the remaining nine galaxies show a central peak with a radial fall-off within 0.2-0.4 r(25). Correcting for the average contribution due to the internal velocitydispersions of a population of giant molecular clouds, the average cloud-cloud velocity dispersion across the galactic disks is 6.1 +/- 1.0 km/s (standard deviation 2.9 km/s), in reasonable agreement with previous measurements for the Galaxy andM33. The cloud-cloud velocity dispersion derived from the CO data is on average two times smaller than the HI velocity dispersion measured in the same galaxies. The low cloud-cloudvelocity dispersion implies that the molecular gas is the critical component determining the stability of the galactic disk against...

  15. OBSERVATIONAL CONSTRAINTS ON THE MOLECULAR GAS CONTENT IN NEARBY STARBURST DWARF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    McQuinn, Kristen B. W.; Skillman, Evan D. [Department of Astronomy, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Benjamin F. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Holtzman, Jon, E-mail: kmcquinn@astro.umn.edu [Department of Astronomy, New Mexico State University, Box 30001, Department 4500, 1320 Frenger Street, Las Cruces, NM 88003 (United States)

    2012-06-01

    Using star formation histories derived from optically resolved stellar populations in 19 nearby starburst dwarf galaxies observed with the Hubble Space Telescope, we measure the stellar mass surface densities of stars newly formed in the bursts. By assuming a star formation efficiency (SFE), we then calculate the inferred gas surface densities present at the onset of the starbursts. Assuming an SFE of 1%, as is often assumed in normal star-forming galaxies, and assuming that the gas was purely atomic, translates to very high H I surface densities ({approx}10{sup 2}-10{sup 3} M{sub Sun} pc{sup -2}), which are much higher than have been observed in dwarf galaxies. This implies either higher values of SFE in these dwarf starburst galaxies or the presence of significant amounts of H{sub 2} in dwarfs (or both). Raising the assumed SFEs to 10% or greater (in line with observations of more massive starbursts associated with merging galaxies), still results in H I surface densities higher than observed in 10 galaxies. Thus, these observations appear to require that a significant fraction of the gas in these dwarf starbursts galaxies was in the molecular form at the onset of the bursts. Our results imply molecular gas column densities in the range 10{sup 19}-10{sup 21} cm{sup -2} for the sample. In the galaxies where CO observations have been made, these densities correspond to values of the CO-H{sub 2} conversion factor (X{sub CO}) in the range >(3-80) Multiplication-Sign 10{sup 20} cm{sup -2} (K km s{sup -1}){sup -1}, or up to 40 Multiplication-Sign greater than Galactic X{sub CO} values.

  16. The frequency and properties of young tidal dwarf galaxies in nearby gas-rich groups

    Science.gov (United States)

    Lee-Waddell, K.; Spekkens, K.; Chandra, P.; Patra, N.; Cuillandre, J.-C.; Wang, J.; Haynes, M. P.; Cannon, J.; Stierwalt, S.; Sick, J.; Giovanelli, R.

    2016-08-01

    We present high-resolution Giant Metrewave Radio Telescope (GMRT) H I observations and deep Canada-France-Hawaii Telescope (CFHT) optical imaging of two galaxy groups: NGC 4725/47 and NGC 3166/9. These data are part of a multi-wavelength unbiased survey of the gas-rich dwarf galaxy populations in three nearby interacting galaxy groups. The NGC 4725/47 group hosts two tidal knots and one dwarf irregular galaxy (dIrr). Both tidal knots are located within a prominent H I tidal tail, appear to have sufficient mass (Mgas ≈ 108 M⊙) to evolve into long-lived tidal dwarf galaxies (TDGs) and are fairly young in age. The NGC 3166/9 group contains a TDG candidate, AGC 208457, at least three dIrrs and four H I knots. Deep CFHT imaging confirms that the optical component of AGC 208457 is bluer - with a 0.28 mag g - r colour - and a few Gyr younger than its purported parent galaxies. Combining the results for these groups with those from the NGC 871/6/7 group reported earlier, we find that the H I properties, estimated stellar ages and baryonic content of the gas-rich dwarfs clearly distinguish tidal features from their classical counterparts. We optimistically identify four potentially long-lived tidal objects associated with three separate pairs of interacting galaxies, implying that TDGs are not readily produced during interaction events as suggested by some recent simulations. The tidal objects examined in this survey also appear to have a wider variety of properties than TDGs of similar mass formed in current simulations of interacting galaxies, which could be the result of pre- or post-formation environmental influences.

  17. THE IMPACT OF MOLECULAR GAS ON MASS MODELS OF NEARBY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Frank, B. S.; Blok, W. J. G. de [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Walter, F. [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Leroy, A. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Carignan, C., E-mail: frank@astron.nl [Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa)

    2016-04-15

    We present CO velocity fields and rotation curves for a sample of nearby galaxies, based on data from HERACLES. We combine our data with THINGS, SINGS, and KINGFISH results to provide a comprehensive sample of mass models of disk galaxies inclusive of molecular gas. We compare the kinematics of the molecular (CO from HERACLES) and atomic (H i from THINGS) gas distributions to determine the extent to which CO may be used to probe the dynamics in the inner part of galaxies. In general, we find good agreement between the CO and H i kinematics, with small differences in the inner part of some galaxies. We add the contribution of the molecular gas to the mass models in our galaxies by using two different conversion factors α{sub CO} to convert CO luminosity to molecular gas mass surface density—the constant Milky Way value and the radially varying profiles determined in recent work based on THINGS, HERACLES, and KINGFISH data. We study the relative effect that the addition of the molecular gas has on the halo rotation curves for Navarro–Frenk–White and the observationally motivated pseudo-isothermal halos. The contribution of the molecular gas varies for galaxies in our sample—for those galaxies where there is a substantial molecular gas content, using different values of α{sub CO} can result in significant differences to the relative contribution of the molecular gas and hence the shape of the dark matter halo rotation curves in the central regions of galaxies.

  18. Observations of dwarfs in nearby voids: implications for galaxy formation and evolution

    CERN Document Server

    Pustilnik, Simon A

    2014-01-01

    The intermediate results of the ongoing study of deep samples of ~200 galaxies residing in nearby voids, are presented. Their properties are probed via optical spectroscopy, ugri surface photometry, and HI 21-cm line measurements, with emphasis on their evolutionary status. We derive directly the hydrogen mass M(HI), the ratio M(HI)/L_B and the evolutionary parameter gas-phase O/H. Their luminosities and integrated colours are used to derive stellar mass M(*) and the second evolutionary parameter -- gas mass-fraction f_g. The colours of the outer parts, typically representative of the galaxy oldest stellar population, are used to estimate the upper limits on time since the beginning of the main SF episode. We compare properties of void galaxies with those of the similar late-type galaxies in denser environments. Most of void galaxies show smaller O/H for their luminosity, in average by ~30%, indicating slower evolution. Besides, the fraction of ~10% of the whole void sample or ~30% of the least luminous void ...

  19. A Pilot Survey of Stellar Tidal Streams in Nearby Spiral Galaxies

    Science.gov (United States)

    Martínez-Delgado, David; Gabany, R. Jay; Peñarrubia, Jorge; Rix, Hans-Walter; Majewski, Steven R.; Trujillo, Ignacio; Pohlen, Michael

    Within the hierarchical framework for galaxy formation, merging and tidal interactions are expected to shape large galaxies to this day. While major mergers are quite rare at present, minor mergers and satellite disruptions-which result in stellar streams-should be common, and are indeed seen in both the Milky Way and the Andromeda Galaxy. As a pilot study, we have carried out ultra-deep, wide-field imaging of some spiral galaxies in the Local Volume, which has revealed external views of such stellar tidal streams at unprecedented detail, with data taken at small robotic telescopes (0.1-0.5m) that provide exquisite surface brightness sensitivity. The goal of this project is to undertake the first systematic and comprehensive imaging survey of stellar tidal streams, from a sample of˜50 nearby Milky Way-like spiral galaxies within 15Mpc, that features a surface brightness sensitivity of˜30mag/arcsec2. The survey will result in estimates of the incidence, size/geometry and stellar luminosity/mass distribution of such streams. This will not only put our Milky Way and M31 in context but, for the first time, also provide an extensive statistical basis for comparison with state-of-the-art, self-consistent cosmological simulations of this phenomenon.

  20. A Search for Stellar Dust Production in Leo P, a Nearby Analog of High Redshift Galaxies

    Science.gov (United States)

    Boyer, Martha; McDonald, Iain; McQuinn, Kristen; Skillman, Evan; Sonneborn, George; Srinivasan, Sundar; van Loon, Jacco Th.; Zijlstra, Albert; Sloan, Greg

    2016-08-01

    The origin of dust in the early Universe is a matter of debate. One of the main potential dust contributors are Asymptotic Giant Branch (AGB) stars, and several studies have been devoted to investigating whether and how AGB dust production changes in metal-poor environments. Of particular interest are the most massive AGB stars (8-10 Msun), which can in principle enter the dust-producing phase lifetimes of these stars. The recently discovered galaxy Leo P provides an irresistible opportunity to search for these massive AGB stars: Leo P is a gas-rich, star-forming galaxy, it is nearby enough for resolved star photometry with Spitzer, and its interstellar medium is 0.4 dex more metal-poor than any other accessible star-forming galaxy. Models predict ~3 massive AGB stars may be present in Leo P, and optical HST observations reveal 7 candidates. We propose to use Spitzer to determine whether these stars are dusty, providing valuable constraints to the dust contribution from AGB stars up to at least redshift 3.2, or 11.7 Gyr ago, when massive spheroidals and Galactic globular clusters were still forming. This is a gain of 2.8 Gyr compared to other accessible galaxies. We also request 1 orbit of joint HST time to confirm whether the AGB candidates in Leo P are indeed massive AGB stars belonging to the galaxy. These observations will provide information crucial for potential JWST followup spectroscopy.

  1. The frequency and properties of young tidal dwarf galaxies in nearby gas-rich groups

    CERN Document Server

    Lee-Waddell, K; Chandra, P; Patra, N; Cuillandre, J -C; Wang, J; Haynes, M P; Cannon, J; Stierwalt, S; Sick, J; Giovanelli, R

    2016-01-01

    We present high-resolution Giant Metrewave Radio Telescope (GMRT) HI observations and deep Canada-France-Hawaii Telescope (CFHT) optical imaging of two galaxy groups: NGC 4725/47 and NGC 3166/9. These data are part of a multi-wavelength unbiased survey of the gas-rich dwarf galaxy populations in three nearby interacting galaxy groups. The NGC 4725/47 group hosts two tidal knots and one dIrr. Both tidal knots are located within a prominent HI tidal tail, appear to have sufficient mass (M_gas~10^8 M_sol) to evolve into long-lived tidal dwarf galaxies (TDGs) and are fairly young in age. The NGC 3166/9 group contains a TDG candidate, AGC 208457, at least three dIrrs and four HI knots. Deep CFHT imaging confirms that the optical component of AGC 208457 is bluer -- with a 0.28 mag g-r colour -- and a few Gyr younger than its purported parent galaxies. Combining the results for these groups with those from the NGC 871/6/7 group reported earlier, we find that the HI properties, estimated stellar ages and baryonic con...

  2. An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS), I. Overview

    CERN Document Server

    Boyer, Martha L; Barmby, Pauline; Bonanos, Alceste Z; Gehrz, Robert D; Gordon, Karl D; Groenewegen, M A T; Lagadec, Eric; Lennon, Daniel; Marengo, Massimo; Meixner, Margaret; Skillman, Evan; Sloan, G C; Sonneborn, George; van Loon, Jacco Th; Zijlstra, Albert

    2014-01-01

    Nearby resolved dwarf galaxies provide excellent opportunities for studying the dust-producing late stages of stellar evolution over a wide range of metallicity (-2.7 75% complete at the tip of the Red Giant Branch for all targeted galaxies, with the exception of the crowded inner regions of IC 10, NGC 185, and NGC 147. This photometric depth ensures that the majority of the dust-producing stars, including the thermally-pulsing AGB stars, are detected in each galaxy. The images map each galaxy to at least twice the half-light radius to ensure that the entire evolved star population is included and to facilitate the statistical subtraction of background and foreground contamination, which is severe at these wavelengths. In this overview, we describe the survey, the data products, and preliminary results. We show evidence for the presence of dust-producing AGB stars in 8 of the targeted galaxies, with metallicities as low as [Fe/H] = -1.9, suggesting that dust production occurs even at low metallicity.

  3. Alma observations of nearby luminous infrared galaxies with various agn energetic contributions using dense gas tracers

    International Nuclear Information System (INIS)

    We present the results of our ALMA Cycle 0 observations, using HCN/HCO+/HNC J = 4-3 lines, of six nearby luminous infrared galaxies with various energetic contributions from active galactic nuclei (AGNs) estimated from previous infrared spectroscopy. These lines are very effective for probing the physical properties of high-density molecular gas around the hidden energy sources in the nuclear regions of these galaxies. We find that HCN to HCO+ J = 4-3 flux ratios tend to be higher in AGN-important galaxies than in starburst-dominated regions, as was seen at the J = 1-0 transition, while there is no clear difference in the HCN-to-HNC J = 4-3 flux ratios among observed sources. A galaxy with a starburst-type infrared spectral shape and very large molecular line widths shows a high HCN-to-HCO+ J = 4-3 flux ratio, which could be due to turbulence-induced heating. We propose that enhanced HCN J = 4-3 emission relative to HCO+ J = 4-3 could be used to detect more energetic activity than normal starbursts, including deeply buried AGNs, in dusty galaxy populations.

  4. The Impact of Molecular Gas on Mass Models of Nearby Galaxies

    CERN Document Server

    Frank, Bradley S; Walter, F; Leroy, A; Carignan, C

    2015-01-01

    We present CO velocity fields and rotation curves for a sample of nearby galaxies, based on data from the HERACLES survey. We combine our data with literature THINGS, SINGS and KINGFISH results to provide a comprehensive sample of mass models of disk galaxies inclusive of molecular gas. We compare the kinematics of the molecular (CO from HERACLES) and atomic (${\\rm H{\\scriptstyle I}}$ from THINGS) gas distributions to determine the extent to which CO may be used to probe the dynamics in the inner part of galaxies. In general, we find good agreement between the CO and ${\\rm H{\\scriptstyle I}}$ kinematics with small differences in the inner part of some galaxies. We add the contribution of the molecular gas to the mass models in our galaxies by using two different conversion factors $\\mathrm{\\alpha_{CO}}$ to convert CO luminosity to molecular gas mass surface density - the constant Milky Way value and the radially varying profiles determined in recent work based on THINGS, HERACLES and KINGFISH data. We study t...

  5. Nearby Clumpy, Gas Rich, Star Forming Galaxies: Local Analogs of High Redshift Clumpy Galaxies

    CERN Document Server

    Garland, C A; Mac Low, M -M; Kreckel, K; Rabidoux, K; Guzmán, R

    2015-01-01

    Luminous compact blue galaxies (LCBGs) have enhanced star formation rates and compact morphologies. We combine Sloan Digital Sky Survey data with HI data of 29 LCBGs at redshift z~0 to understand their nature. We find that local LCBGs have high atomic gas fractions (~50%) and star formation rates per stellar mass consistent with some high redshift star forming galaxies. Many local LCBGs also have clumpy morphologies, with clumps distributed across their disks. Although rare, these galaxies appear to be similar to the clumpy star forming galaxies commonly observed at z~1-3. Local LCBGs separate into three groups: 1. Interacting galaxies (~20%); 2. Clumpy spirals (~40%); 3. Non-clumpy, non-spirals with regular shapes and smaller effective radii and stellar masses (~40%). It seems that the method of building up a high gas fraction, which then triggers star formation, is not the same for all local LCBGs. This may lead to a dichotomy in galaxy characteristics. We consider possible gas delivery scenarios and sugges...

  6. Hydrogen fluoride toward luminous nearby galaxies: NGC 253 and NGC 4945

    Energy Technology Data Exchange (ETDEWEB)

    Monje, R. R.; Lis, D. C.; Phillips, T. G. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125-4700 (United States); Lord, S. [Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States); Falgarone, E. [LERMA/LRA, Ecole Normale Supérieure and Observatoire de Paris, 24 rue Lhomond, F-75005 Paris (France); Neufeld, D. A. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Güsten, R., E-mail: raquel@caltech.edu [Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)

    2014-04-10

    We present the detection of hydrogen fluoride (HF) in two luminous nearby galaxies, NGC 253 and NGC 4945 using the Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory. The HF line toward NGC 253 has a P-Cygni profile, while an asymmetric absorption profile is seen toward NGC 4945. The P-Cygni profile in NGC 253 suggests an outflow of molecular gas with a mass of M(H{sub 2}){sub out} ∼ 1 × 10{sup 7} M {sub ☉} and an outflow rate as large as M-dot ∼6.4 M {sub ☉} yr{sup –1}. In the case of NGC 4945, the axisymmetric velocity components in the HF line profile are compatible with the interpretation of a fast-rotating nuclear ring surrounding the nucleus and the presence of inflowing gas. The gas falls into the nucleus with an inflow rate of ≤1.2 M {sub ☉} yr{sup –1}, inside an inner radius of ≤200 pc. The gas accretion rate to the central active galactic nucleus is much smaller, suggesting that the inflow may be triggering a nuclear starburst. From these results, the HF J = 1-0 line is seen to provide an important probe of the kinematics of absorbing material along the sight-line to nearby galaxies with bright dust continuum and a promising new tracer of molecular gas in high-redshift galaxies.

  7. Herschel Far-Infrared and Sub-millimeter Photometry for the KINGFISH Sample of Nearby Galaxies

    CERN Document Server

    Dale, D A; Engelbracht, C W; Hinz, J L; Krause, O; Montiel, E J; Roussel, H; Appleton, P N; Armus, L; Beirao, P; Bolatto, A D; Brandl, B R; Calzetti, D; Crocker, A F; Croxall, K V; Draine, B T; Galametz, M; Gordon, K D; Groves, B A; Hao, C -N; Helou, G; Hunt, L K; Johnson, B D; Kennicutt, R C; Koda, J; Leroy, A K; Li, Y; Meidt, S E; Miller, A E; Murphy, E J; Rahman, N; Rix, H -W; Sandstrom, K M; Sauvage, M; Schinnerer, E; Skibba, R A; Smith, J -D T; Tabatabaei, F S; Walter, F; Wilson, C D; Wolfire, M G; Zibetti, S

    2011-01-01

    New far-infrared and sub-millimeter photometry from the Herschel Space Observatory is presented for 61 nearby galaxies from the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) sample. The spatially-integrated fluxes are largely consistent with expectations based on Spitzer far-infrared photometry and extrapolations to longer wavelengths using popular dust emission models. Dwarf irregular galaxies are notable exceptions, as already noted by other authors, as their 500um emission shows evidence for a sub-millimeter excess. In addition, the fraction of dust heating attributed to intense radiation fields associated with photo-dissociation regions is found to be (21+/-4)% larger when Herschel data are included in the analysis. Dust masses obtained from the dust emission models of Draine & Li are found to be on average nearly a factor of two higher than those based on single-temperature modified blackbodies, as single blackbody curves do not capture the full range of dust tempera...

  8. Rotational Dynamics and Star Formation in the Nearby Dwarf Galaxy NGC 5238

    CERN Document Server

    Cannon, John M; Teich, Yaron G; Ball, Catherine; Banovetz, John; Brock, Annika; Eisner, Brian A; Fitzgibbon, Kathleen; Miazzo, Masao; Nizami, Asra; Reilly, Bridget; Ruvolo, Elizabeth; Singer, Quinton

    2016-01-01

    We present new HI spectral line images of the nearby low-mass galaxy NGC 5238, acquired with the Karl G. Jansky Very Large Array (VLA). Located at a distance of 4.51+/-0.04 Mpc, NGC 5238 is an actively star-forming galaxy with widespread H-alpha and UV continuum emission. The source is included in many ongoing and recent nearby galaxy surveys, but until this work the spatially resolved qualities of its neutral interstellar medium have remained unstudied. Our HI images resolve the disk on physical scales of ~400 pc, allowing us to undertake a detailed comparative study of the gaseous and stellar components. The HI disk is asymmetric in the outer regions, and the areas of high HI mass surface density display a crescent-shaped morphology that is slightly offset from the center of the stellar populations. The HI column density exceeds 10^21 cm^-2 in much of the disk. We quantify the degree of co-spatiality of dense HI gas and sites of ongoing star formation as traced by far-UV and H-alpha emission. The neutral ga...

  9. The Nature of Starbursts. I. The Star Formation Histories of Eighteen Nearby Starburst Dwarf Galaxies

    Science.gov (United States)

    McQuinn, Kristen B. W.; Skillman, Evan D.; Cannon, John M.; Dalcanton, Julianne; Dolphin, Andrew; Hidalgo-Rodríguez, Sebastian; Holtzman, Jon; Stark, David; Weisz, Daniel; Williams, Benjamin

    2010-09-01

    We use archival Hubble Space Telescope observations of resolved stellar populations to derive the star formation histories (SFHs) of 18 nearby starburst dwarf galaxies. In this first paper, we present the observations, color-magnitude diagrams (CMDs), and the SFHs of the 18 starburst galaxies, based on a homogeneous approach to the data reduction, differential extinction, and treatment of photometric completeness. We adopt a star formation rate (SFR) threshold normalized to the average SFR of the individual system as a metric for classifying starbursts in SFHs derived from resolved stellar populations. This choice facilitates finding not only the currently bursting galaxies but also "fossil" bursts increasing the sample size of starburst galaxies in the nearby (D fossil bursts. From our reconstructed SFHs, it is evident that the elevated SFRs of a burst are sustained for hundreds of Myr with variations on small timescales. A long >100 Myr temporal baseline is thus fundamental to any starburst definition or identification method. The longer lived bursts rule out rapid "self-quenching" of starbursts on global scales. The bursting galaxies' gas consumption timescales are shorter than the Hubble time for all but one galaxy confirming the short-lived nature of starbursts based on fuel limitations. Additionally, we find that the strength of the Hα emission usually correlates with the CMD-based SFR during the last 4-10 Myr. However, in four cases, the Hα emission is significantly less than what is expected for models of starbursts; the discrepancy is due to the SFR changing on timescales of a few Myr. The inherently short timescale of the Hα emission limits identifying galaxies as starbursts based on the current characteristics which may or may not be representative of the recent SFH of a galaxy. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the

  10. SDSS1133: An Unusually Persistent Transient in a Nearby Dwarf Galaxy

    CERN Document Server

    Koss, Michael; Mushotzky, Richard; Hung, Chao Ling; Veilleux, Sylvain; Trakhtenbrot, Benny; Schawinski, Kevin; Stern, Daniel; Smith, Nathan; Li, Yanxia; Man, Allison; Filippenko, Alexei V; Mauerhan, Jon C; Stanek, Kris; Sanders, David

    2014-01-01

    We have discovered an unusual source offset by 0.8 kpc from a nearby dwarf galaxy while performing a survey to detect recoiling black holes. The object, SDSS J113323.97+550415.8, exhibits broad emission lines and strong variability. While originally classified as a supernova (SN) because of its nondetection in 2005, we detect it in recent and past observations over 63 yr. Using high-resolution adaptive optics observations, we constrain the source emission region to be 10 yr), larger than that of unusually luminous supernovae such as SN 1988Z, suggesting one of the most extreme episodes of pre-SN mass loss ever discovered.

  11. Carbon abundances and radial gradients in NGC300 and other nearby spiral galaxies

    CERN Document Server

    Cipriano, L Toribio San; Esteban, C

    2014-01-01

    We present preliminary results of deep echelle spectrophotometry of a sample of HII regions along the disk of the Scd galaxy NGC300 obtained with the Ultraviolet and Visual Echelle Spectrograph (UVES) at the Very Large Telescope (VLT) with the aim of detect and measure very faint OII and CII permitted lines. We focus this study on the C and O abundances obtained from faint optical recombination lines (ORLs) instead of the most commonly used collisionally excited lines (CELs). We have derived the ionic abundances of C++ from the CII 4267 angstrom RL and O++ from the multiplet 1 of OII around 4649 angstrom in several objects. Finally, we have computed the radial gradients of C/H, O/H and C/O ratios in NGC300 from RLs, which has allowed the comparison with similar data obtained by our group in other nearby spiral galaxies.

  12. The host galaxy/AGN connection in nearby early-type galaxies. Is there a miniature radio-galaxy in every "core" galaxy?

    Science.gov (United States)

    Balmaverde, B.; Capetti, A.

    2006-02-01

    This is the second of a series of three papers exploring the connection between the multiwavelength properties of AGN in nearby early-type galaxies and the characteristics of their hosts. We selected two samples with 5 GHz VLA radio flux measurements down to 1 mJy, reaching levels of radio luminosity as low as 1036 erg s-1. In Paper I we presented a study of the surface brightness profiles for the 65 objects with available archival HST images out of the 116 radio-detected galaxies. We classified early-type galaxies into "core" and "power-law" galaxies, discriminating on the basis of the slope of their nuclear brightness profiles, following the Nukers scheme. Here we focus on the 29 core galaxies (hereafter CoreG). We used HST and Chandra data to isolate their optical and X-ray nuclear emission. The CoreG invariably host radio-loud nuclei, with an average radio-loudness parameter of Log R = L5 {GHz} / LB ˜ 3.6. The optical and X-ray nuclear luminosities correlate with the radio-core power, smoothly extending the analogous correlations already found for low luminosity radio-galaxies (LLRG) toward even lower power, by a factor of ˜ 1000, covering a combined range of 6 orders of magnitude. This supports the interpretation of a common non-thermal origin of the nuclear emission also for CoreG. The luminosities of the nuclear sources, most likely dominated by jet emission, set firm upper limits, as low as L/L_Edd ˜ 10-9 in both the optical and X-ray band, on any emission from the accretion process. The similarity of CoreG and LLRG when considering the distributions host galaxies luminosities and black hole masses, as well as of the surface brightness profiles, indicates that they are drawn from the same population of early-type galaxies. LLRG represent only the tip of the iceberg associated with (relatively) high activity levels, with CoreG forming the bulk of the population. We do not find any relationship between radio-power and black hole mass. A minimum black hole

  13. Recent star formation in nearby 3CR radio-galaxies from UV HST observations

    CERN Document Server

    Baldi, Ranieri D

    2008-01-01

    We analyzed HST images of 31 nearby (z <~ 0.1) 3CR radio-galaxies. We compared their UV and optical images to detect evidence of recent star formation. Six objects were excluded because they are highly nucleated or had very low UV count rates. After subtracting the emission from their nuclei and/or jets, 12 of the remaining 25 objects, presenting an UV/optical colors NUV - r < 5.4, are potential star-forming candidates. Considering the contamination from other AGN-related processes (UV emission lines, nebular continuum, and scattered nuclear light), there are 6 remaining star-forming "blue" galaxies. We then divide the radio galaxies, on the basis of the radio morphology, radio power, and diagnostic optical line ratios, into low and high excitation galaxies, LEG and HEG. While there is no correlation between the FR type (or radio power) and color, the FR type is clearly related to the spectroscopic type. In fact, all HEG (with one possible exception) show morphological evidence of recent star formation ...

  14. Revised Mass-to-Light Ratios For Nearby Galaxy Groups and Clusters

    CERN Document Server

    Shan, Yutong; Courteau, Stephane

    2014-01-01

    We present a detailed investigation of the cluster stellar mass-to-light (M*/L) ratio and cumulative stellar masses, derived on a galaxy-by-galaxy basis, for 12 massive (M500 ~ 10^14 - 10^15 Msun), nearby clusters with available optical imaging data from the Sloan Digital Sky Survey Data Release 10 and X-ray data from the Chandra X-ray Observatory. Our method involves a statistical cluster membership using both photometric and spectroscopic redshifts when available to maximize completeness whilst minimizing contamination effects. We show that different methods of estimating the stellar mass-to-light ratio from observed photometry result in systematic discrepancies in the total stellar masses and average mass-to-light ratios of cluster galaxies. Nonetheless, all conversion methodologies point to a lack of correlation between M*/Li and total cluster mass, even though low-mass groups contain relatively more blue galaxies. We also find no statistically significant correlation between M*/Li and the fraction of blu...

  15. The nuclear and integrated far-infrared emission of nearby Seyfert galaxies

    CERN Document Server

    García-González, J; Hernán-Caballero, A; Pereira-Santaella, M; Ramos-Almeida, C; Pulido, J A Acosta; Díaz-Santos, T; Esquej, P; González-Martín, O; Ichikawa, K; López-Rodríguez, E; Povic, M; Roche, P F; Sánchez-Portal, M

    2016-01-01

    We present far-infrared (FIR) $70-500\\,\\mu$m imaging observations obtained with Herschel/PACS and SPIRE of 33 nearby (median distance of 30 Mpc) Seyfert galaxies from the Revised Shapley-Ames (RSA) catalogue. We obtain the FIR nuclear ($r=1\\,$kpc and $r=2\\,$kpc) and integrated spectral energy distributions (SEDs). We estimate the unresolved nuclear emission at 70 $\\mu$m and we fit the nuclear and integrated FIR SEDs with a grey body model. We find that the integrated FIR emission of the RSA Seyferts in our sample is dominated by emission from the host galaxy, with dust properties similar to those of normal galaxies (non AGN). We use four criteria to select galaxies whose nuclear $70\\,\\mu$m emission has a significant AGN contribution: (1) elevated 70/160 $\\mu$m flux ratios, (2)spatially resolved, high dust temperature gradient, (3) $70\\,\\mu$m excess emission with respect to the fit of the FIR SEDs with a grey body, and (4) excess of nuclear SFR obtained from $70\\,\\mu$m over SFR from mid-infrared indicators. 16...

  16. Satellite accretion in action: a tidally disrupting dwarf spheroidal around the nearby spiral galaxy NGC 253

    CERN Document Server

    Romanowsky, Aaron J; Martin, Nicolas F; Morales, Gustavo; Jennings, Zachary G; GaBany, R Jay; Brodie, Jean P; Grebel, Eva K; Schedler, Johannes; Sidonio, Michael

    2015-01-01

    We report the discovery of NGC 253-dw2, a dwarf spheroidal (dSph) galaxy candidate undergoing tidal disruption around a nearby spiral galaxy, NGC 253 in the Sculptor group: the first such event identified beyond the Local Group. The dwarf was found using small-aperture amateur telescopes, and followed up with Suprime-Cam on the 8 m Subaru Telescope in order to resolve its brightest stars. Using g- and R_c-band photometry, we detect a red giant branch consistent with an old, metal-poor stellar population at a distance of ~ 3.5 Mpc. From the distribution of likely member stars, we infer a highly elongated shape with a semi-major axis half-light radius of (2 +/- 0.4) kpc. Star counts also yield a luminosity estimate of ~ 2x10^6 L_Sun,V (M_V ~ -10.7). The morphological properties of NGC 253-dw2 mark it as distinct from normal dSphs and imply ongoing disruption at a projected distance of ~ 50 kpc from the main galaxy. Our observations support the hierarchical paradigm wherein massive galaxies continously accrete l...

  17. The Effect of Structure and Star Formation on the Gas Content of Nearby Galaxies

    CERN Document Server

    Brown, Toby; Cortese, Luca; Kilborn, Virginia; Haynes, Martha P; Giovanelli, Riccardo

    2015-01-01

    We revisit the main HI-to-stellar mass ratio (gas fraction) scaling relations, taking advantage of the HI spectral stacking technique to understand the dependence of gas content on the structural and star formation properties of nearby galaxies. This work uses a volume-limited, multi-wavelength sample of ~25,000 galaxies, selected according to stellar mass (10^9 M_sol < M_* < 10^11.5 M_sol) and redshift (0.02 < z < 0.05) from the Sloan Digital Sky Survey, and with HI data from the Arecibo Legacy Fast ALFA survey. We bin according to multiple parameters of galaxies spanning the full gas-poor to -rich regime in order to disentangle the dominance of different components and processes in influencing gas content. For the first time, we show that the scaling relations of gas fraction with stellar mass and stellar surface density are primarily driven by a combination of the underlying galaxy bimodality in specific star formation rate and the integrated Kennicutt-Schmidt law. Finally, we produce tentative...

  18. A Deeper Look at Faint H$\\alpha$ Emission in Nearby Dwarf Galaxies

    CERN Document Server

    Lee, Janice C; McDonald, Michael; Hilbert, Bryan

    2016-01-01

    We present deep H$\\alpha$ imaging of three nearby dwarf galaxies, carefully selected to optimize observations with the Maryland-Magellan Tunable Filter (MMTF) on the Magellan 6.5m telescope. An effective bandpass of $\\sim$13\\AA\\ is used, and the images reach 3$\\sigma$ flux limits of $\\sim$8$\\times10^{-18}$ ergs s$^{-1}$ cm$^{-2}$, which is about an order of magnitude lower than standard narrowband observations obtained by the most recent generation of local H$\\alpha$ galaxy surveys. The observations were originally motivated by the finding that the H$\\alpha$/FUV flux ratio of galaxies systematically declines as global galactic properties such as the star formation rate and stellar mass decrease. The three dwarf galaxies selected for study have star formation rates, that when calculated from their H$\\alpha$ luminosities using standard conversion recipes, are $\\sim$50\\% of those based on the FUV. Follow-up studies of many of the potential causes for the trends in the H$\\alpha$/FUV flux ratio have been performed...

  19. The Abundance Properties of Nearby Late-Type Galaxies.I. The Data

    CERN Document Server

    Pilyugin, L S; Kniazev, A Y

    2014-01-01

    We investigate the oxygen and nitrogen abundance distributions across the optical disks of 130 nearby late-type galaxies using around 3740 published spectra of HII regions. We use these data in order to provide homogeneous abundance determinations for all objects in the sample, including HII regions in which not all of the usual diagnostic lines were measured. Examining the relation between N and O abundances in these galaxies we find that the abundances in their centres and at their isophotal R_25 disk radii follow the same relation. The variation in N/H at a given O/H is around 0.3 dex. We suggest that the observed spread in N/H may be partly caused by the time delay between N and O enrichment and the different star formation histories in galaxies of different morphological types and dimensions. We study the correlations between the abundance properties (central O and N abundances, radial O and N gradients) of a galaxy and its morphological type and dimension.

  20. SMT CO (2-1) Observations of Nearby Star-Forming Galaxies

    CERN Document Server

    Jiang, Xue-Jian; Gu, Qiusheng; Wang, Junzhi; Zhang, Zhi-Yu

    2014-01-01

    We present CO $J$=2-1 observations towards 32 nearby gas-rich star-forming galaxies selected from the ALFALFA and WISE catalogs, using the Sub-millimeter Telescope. Our sample is selected to be dominated by intermediate-$M_{\\rm *}$ galaxies. The scaling-relations between molecular gas, atomic gas and galactic properties (stellar mass, NUV$- r$ and WISE color W3$-$W2) are examined and discussed. Our results show that (1). In the galaxies with stellar mass $M_{\\rm *}$ $\\leqslant 10^{10}$ $M_{\\odot}$, HI fraction ($f_{\\rm HI}$ $\\equiv$ $M_{\\rm HI}$/$M_{\\rm *}$) is significantly higher than that of more massive galaxies, while H$_2$ gas fraction ($f_{\\rm H_2}$ $\\equiv$ $M_{\\rm H_2}$/$M_{\\rm *}$) remain nearly unchanged. (2). Comparing with $f_{\\rm H_2}$, $f_{\\rm HI}$ correlates better with both $M_{\\rm *}$ and NUV$- r$. (3). A new parameter, WISE color W3$-$W2 (12\\,$\\mu$m$-$4.6\\,$\\mu$m) is introduced, which is similar to NUV$- r$ in tracing star formation activity, and we find that W3$-$W2 has a tighter anti-corr...

  1. Globular clusters as tracers of the halo assembly of nearby central cluster galaxies

    CERN Document Server

    Hilker, Michael

    2015-01-01

    The properties of globular cluster systems (GCSs) in the core of the nearby galaxy clusters Fornax and Hydra I are presented. In the Fornax cluster we have gathered the largest radial velocity sample of a GCS system so far, which enables us to identify photometric and kinematic sub-populations around the central galaxy NGC 1399. Moreover, ages, metallicities and [alpha/Fe] abundances of a sub-sample of 60 bright globular clusters (GCs) with high S/N spectroscopy show a multi-modal distribution in the correlation space of these three parameters, confirming heterogeneous stellar populations in the halo of NGC 1399. In the Hydra I cluster very blue GCs were identified. They are not uniformly distributed around the central galaxies. 3-color photometry including the U-band reveals that some of them are of intermediate age. Their location coincides with a group of dwarf galaxies under disruption. This is evidence of a structurally young stellar halo 'still in formation', which is also supported by kinematic measure...

  2. Probing the magnetic field of the nearby galaxy pair Arp 269

    Science.gov (United States)

    Nikiel-Wroczyński, B.; Jamrozy, M.; Soida, M.; Urbanik, M.; Knapik, J.

    2016-06-01

    We present a multiwavelength radio study of the nearby galaxy pair Arp 269 (NGC 4490/85). High sensitivity to extended structures gained by using the merged interferometric and single-dish maps allowed us to reveal a previously undiscovered extension of the radio continuum emission. Its direction is significantly different from that of the neutral gas tail, suggesting that different physical processes might be involved in their creation. The population of radio-emitting electrons is generally young, signifying an ongoing, vigorous star formation - this claim is supported by strong magnetic fields (over 20 μG), similar to the ones found in much larger spiral galaxies. From the study of the spectral energy distribution, we conclude that the electron population in the intergalactic bridge between member galaxies originates from the disc areas, and therefore its age (approximately 3.7-16.9 Myr, depending on the model used) reflects the time-scale of the interaction. We have also discovered an angularly near compact steep source - which is a member of a different galaxy pair - at a redshift of approximately 0.125.

  3. Chandra and Very Large Array Observations of the Nearby Sd Galaxy NGC 45

    Science.gov (United States)

    Pannuti, Thomas G.; Swartz, Douglas A.; Laine, Seppo; Schlegel, Eric M.; Lacey, Christina K.; Moffitt, William P.; Sharma, Biswas; Lackey-Stewart, Aaron M.; Kosakowski, Alekzander R.; Filipović, Miroslav D.; Payne, Jeffrey L.

    2015-09-01

    We present an analysis of high angular resolution observations made in the X-ray and the radio with the Chandra X-ray Observatory and the Karl Jansky Very Large Array (VLA), respectively, of the nearby spiral galaxy NGC 45. This galaxy is the third that we have considered in a study of the supernova remnant (SNR) populations of nearby spiral galaxies and the present work represents the first detailed analysis of the discrete X-ray and radio source populations of this galaxy. We analyzed data sets from the three pointed observations made of this galaxy with Chandra along with a merged data set obtained from combining these data sets: the total effective exposure time of the merged data set is 63515 s. A total of 25 discrete X-ray sources are found in the entire field of view of the ACIS-S3 chip, with 16 sources found within the visual extent of the galaxy. We estimate that as many as half of the sources detected in the entire field of view of the ACIS-S3 chip and seven of the sources detected in the optical extent of NGC 45 may be background sources. We analyzed the spectral properties of the discrete X-ray sources within the galaxy and conclude that the majority of these sources are X-ray binaries. We have searched for counterparts at different wavelengths to the discrete X-ray sources and we find two associations: one with a star cluster and the other with a background galaxy. We have found one source that is clearly variable within one observation and seven that are seen to vary from one observation to another. We also conduct a photometric analysis to determine the near-infrared fluxes of the discrete X-ray sources in Spitzer Infrared Array Camera channels. We constructed a cumulative luminosity function of the discrete X-ray sources seen toward NGC 45: taking into account simultaneously the luminosity function of background sources, the fitted slope of the cumulative luminosity function Γ = -1.3{}-1.6+0.7 (all error bounds correspond to 90% confidence

  4. The mass of the central black hole in the nearby Seyfert galaxy NGC 5273

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, Misty C.; Horenstein, Daniel; Bazhaw, Craig; Manne-Nicholas, Emily R.; Ou-Yang, Benjamin J.; Anderson, Matthew; Jones, Jeremy; Norris, Ryan P.; Parks, J. Robert; Saylor, Dicy; Teems, Katherine G.; Turner, Clay, E-mail: bentz@astro.gsu.edu [Department of Physics and Astronomy, Georgia State University, 25 Park Place, Suite 600, Atlanta, GA 30303 (United States)

    2014-11-20

    We present the results of a reverberation-mapping program targeting NGC 5273, a nearby early-type galaxy with a broad-lined active galactic nucleus (AGN). Over the course of the monitoring program, NGC 5273 showed strong variability that allowed us to measure time delays in the responses of the broad optical recombination lines to changes in the continuum flux. A weighted average of these measurements results in a black hole mass determination of M {sub BH} = (4.7 ± 1.6) × 10{sup 6} M {sub ☉}. An estimate of the size of the black hole sphere of influence in NGC 5273 puts it just at the limit of the resolution achievable with current ground-based large aperture telescopes. NGC 5273 is therefore an important future target for a black hole mass determination from stellar dynamical modeling, especially because it is the only nearby early-type galaxy hosting an AGN with a reverberation-based mass, allowing the best comparison for the masses determined from these two techniques.

  5. The Mass of the Central Black Hole in the Nearby Seyfert Galaxy NGC5273

    CERN Document Server

    Bentz, Misty C; Bazhaw, Craig; Manne-Nicholas, Emily R; Ou-Yang, Benjamin J; Anderson, Matthew; Jones, Jeremy; Norris, Ryan P; Parks, J Robert; Saylor, Dicy; Teems, Katherine G; Turner, Clay

    2014-01-01

    We present the results of a reverberation-mapping program targeting NGC5273, a nearby early-type galaxy with a broad-lined active galactic nucleus. Over the course of the monitoring program, NGC5273 showed strong variability that allowed us to measure time delays in the responses of the broad optical recombination lines to changes in the continuum flux. A weighted average of these measurements results in a black hole mass determination of $M_{\\rm BH} = (4.7 \\pm 1.6) \\times 10^6$ M$_{\\odot}$. An estimate of the size of the black hole sphere of influence in NGC5273 puts it just at the limit of the resolution achievable with current ground-based large aperture telescopes. NGC5273 is therefore an important future target for a black hole mass determination from stellar dynamical modeling, especially because it is the only nearby early-type galaxy hosting an AGN with a reverberation-based mass, allowing the best comparison for the masses determined from these two techniques.

  6. A Survey of the Molecular ISM Properties of Nearby Galaxies using the Herschel FTS

    CERN Document Server

    Kamenetzky, J; Glenn, J; Maloney, P R; Conley, A

    2014-01-01

    The 12CO J=4-3 to J=13-12 lines of the interstellar medium from nearby galaxies, newly observable with the Herschel SPIRE Fourier Transform Spectrometer (FTS), offer an opportunity to study warmer, more luminous molecular gas than that traced by 12CO J=1-0. Here we present a survey of 17 nearby infrared-luminous galaxy systems (21 pointings). In addition to photometric modeling of dust, we modeled full 12CO spectral line energy distributions from J=1-0 to J=13-12 with two components of warm and cool CO gas, and included LTE analysis of [CI], [CII], [NII] and H2 lines. CO is emitted from a low-pressure/high-mass component traced by the low-J lines and a high-pressure/low-mass component which dominates the luminosity. We found that, on average, the ratios of the warm/cool pressure, mass, and 12CO luminosity are 60 +/- 30, 0.11 +/- 0.02, and 15.6 +/- 2.7. The gas-to-dust-mass ratios are < 120 throughout the sample. The 12CO luminosity is dominated by the high-J lines and is 4 $\\times 10^{-4}$ LFIR on average....

  7. A CENSUS OF BROAD-LINE ACTIVE GALACTIC NUCLEI IN NEARBY GALAXIES: COEVAL STAR FORMATION AND RAPID BLACK HOLE GROWTH

    International Nuclear Information System (INIS)

    We present the first quantified, statistical map of broad-line active galactic nucleus (AGN) frequency with host galaxy color and stellar mass in nearby (0.01 < z < 0.11) galaxies. Aperture photometry and z-band concentration measurements from the Sloan Digital Sky Survey are used to disentangle AGN and galaxy emission, resulting in estimates of uncontaminated galaxy rest-frame color, luminosity, and stellar mass. Broad-line AGNs are distributed throughout the blue cloud and green valley at a given stellar mass, and are much rarer in quiescent (red sequence) galaxies. This is in contrast to the published host galaxy properties of weaker narrow-line AGNs, indicating that broad-line AGNs occur during a different phase in galaxy evolution. More luminous broad-line AGNs have bluer host galaxies, even at fixed mass, suggesting that the same processes that fuel nuclear activity also efficiently form stars. The data favor processes that simultaneously fuel both star formation activity and rapid supermassive black hole accretion. If AGNs cause feedback on their host galaxies in the nearby universe, the evidence of galaxy-wide quenching must be delayed until after the broad-line AGN phase.

  8. The JCMT Nearby Galaxies Legacy Survey I. Star Forming Molecular Gas in Virgo Cluster Spiral Galaxies

    CERN Document Server

    Wilson, C D; Israel, F P; Serjeant, S; Bendo, G; Brinks, E; Clements, D; Courteau, S; Irwin, J; Knapen, J H; Leech, J; Matthews, H E; Muehle, S; Mortier, A M J; Petitpas, G; Sinukoff, E; Spekkens, K; Tan, B K; Tilanus, R P J; Usero, A; Van der Werf, P P; Wiegert, T; Zhu, M

    2008-01-01

    We present large-area maps of the CO J=3-2 emission obtained at the James Clerk Maxwell Telescope for four spiral galaxies in the Virgo Cluster. We combine these data with published CO J=1-0, 24 micron, and Halpha images to measure the CO line ratios, molecular gas masses, and instantaneous gas depletion times. For three galaxies in our sample (NGC 4254, NGC4321, and NGC 4569), we obtain molecular gas masses of 7E8-3E9 Msun and disk-averaged instantaneous gas depletion times of 1.1-1.7 Gyr. We argue that the CO J=3-2 line is a better tracer of the dense star forming molecular gas than the CO J=1-0 line, as it shows a better correlation with the star formation rate surface density both within and between galaxies. NGC 4254 appears to have a larger star formation efficiency(smaller gas depletion time), perhaps because it is on its first passage through the Virgo Cluster. NGC 4569 shows a large-scale gradient in the gas properties traced by the CO J=3-2/J=1-0 line ratio, which suggests that its interaction with ...

  9. The abundance and spatial distribution of ultra-diffuse galaxies in nearby galaxy clusters

    CERN Document Server

    van der Burg, Remco F J; Hoekstra, Henk

    2016-01-01

    Recent observations have highlighted a significant population of faint but large (r_eff>1.5 kpc) galaxies in the Coma cluster. The origin of these Ultra Diffuse Galaxies (UDGs) remains puzzling, as the interpretation of these observational results has been hindered by the subjective selection of UDGs, and the limited study of only the Coma (and some examples in the Virgo-) cluster. In this paper we extend the study of UDGs using eight clusters in the redshift range 0.044galaxies. We find that the abundance of the UDGs we can detect increases with cluster mass, reaching ~200 in typical haloes of M200~10^15 Msun. The cluster UDGs have colours consistent with the cluster red sequence, and have a steep size distribution that declines as n ~ r_eff^-3.4. Their radial distribution is significantly st...

  10. Astrochemistry and star formation in nearby galaxies: from galaxy disks to hot nuclei

    Science.gov (United States)

    Aalto, S.

    2016-05-01

    Studying the molecular phase of the interstellar medium in galaxies is fundamental for the understanding of the onset and evolution of compact and extended star formation, and of the growth of supermassive black holes. Molecular line emission is an excellent tracer of chemical, physical and dynamical conditions in the cold neutral gas. Key molecules in extragalactic studies are e.g. HCN, HCO+, HC3N, SiO, CH3OH, H2O. Furthermore, we can use IR excited molecular emission to probe the very inner regions of luminous infrared galaxies allowing us to get past the optically thick dust barrier of the compact obscured nuclei where lines of CO, HCN and HCO+ in their vibrational ground state (ν=0) may be self-absorbed. Finally, molecular outflows and their chemistry are briefly discussed - including new ALMA results on for example the outflow of the lenticular galaxy NGC1377 and a study of the chemistry of the outflow of the quasar Mrk231.

  11. KINGFISH -- Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel: Survey Description and Image Atlas

    CERN Document Server

    Kennicutt, R C; Aniano, G; Appleton, P; Armus, L; Beirao, P; Bolatto, A D; Brandl, B; Crocker, A; Croxall, K; Dale, D A; Meyer, J Dononvan; Draine, B T; Engelbracht, C W; Galametz, M; Gordon, K D; Groves, B; Hao, C -N; Helou, G; Hinz, J; Hunt, L K; Johnson, B; Koda, J; Krause, O; Leroy, A K; Li, Y; Meidt, S; Montiel, E; Murphy, E J; Rahman, N; Rix, H -W; Roussel, H; Sandstrom, K; Sauvage, M; Schinnerer, E; Skibba, R; Smith, J -D T; Srinivasan, S; Vigroux, L; Walter, F; Wilson, C D; Wolfire, M; Zibetti, S

    2011-01-01

    The KINGFISH project (Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel) is an imaging and spectroscopic survey of 61 nearby (d < 30 Mpc) galaxies, chosen to cover a wide range of galaxy properties and local interstellar medium (ISM) environments found in the nearby Universe. Its broad goals are to characterize the ISM of present-day galaxies, the heating and cooling of their gaseous and dust components, and to better understand the physical processes linking star formation and the ISM. KINGFISH is a direct descendant of the Spitzer Infrared Nearby Galaxies Survey (SINGS), which produced complete Spitzer imaging and spectroscopic mapping and a comprehensive set of multi-wavelength ancillary observations for the sample. The Herschel imaging consists of complete maps for the galaxies at 70, 100, 160, 250, 350, and 500 microns. The spectal line imaging of the principal atomic ISM cooling lines ([OI]63um, [OIII]88um, [NII]122,205um, and [CII]158um) covers the subregions in the centers and di...

  12. The nuclear and integrated far-infrared emission of nearby Seyfert galaxies

    Science.gov (United States)

    García-González, J.; Alonso-Herrero, A.; Hernán-Caballero, A.; Pereira-Santaella, M.; Ramos-Almeida, C.; Acosta-Pulido, J. A.; Díaz-Santos, T.; Esquej, P.; González-Martín, O.; Ichikawa, K.; López-Rodríguez, E.; Povic, M.; Roche, P. F.; Sánchez-Portal, M.

    2016-06-01

    We present far-infrared (FIR) 70-500 μm imaging observations obtained with Herschel/Photodetector Array Camera (PACS) and Spectral and Photometric Imaging REceiver (SPIRE) of 33 nearby (median distance of 30 Mpc) Seyfert galaxies from the Revised Shapley-Ames (RSA) catalogue. We obtain the FIR nuclear (r = 1 kpc and r = 2 kpc) and integrated spectral energy distributions (SEDs). We estimate the unresolved nuclear emission at 70 μm and we fit the nuclear and integrated FIR SEDs with a grey body model. We find that the integrated FIR emission of the RSA Seyferts in our sample is dominated by emission from the host galaxy, with dust properties similar to those of normal galaxies (non-AGN). We use four criteria to select galaxies whose nuclear 70 μm emission has a significant AGN contribution: (1) elevated 70/160 μm flux ratios, (2) spatially resolved, high dust temperature gradient, (3) 70 μm excess emission with respect to the fit of the FIR SEDs with a grey body, and (4) excess of nuclear SFR obtained from 70 μm over SFR from mid-infrared indicators. 16 galaxies (48 per cent of the initial sample) satisfy at least one of these conditions, whereas 10 satisfy half or more. After careful examination of these, we select six bona fide candidates (18 per cent of the initial sample) and estimate that ˜40-70 per cent of their nuclear (r = 1-2 kpc) 70 μm emission is contributed by dust heated by the AGN.

  13. A survey of the molecular ISM properties of nearby galaxies using the Herschel FTS

    International Nuclear Information System (INIS)

    The 12CO J = 4 → 3 to J = 13 → 12 lines of the interstellar medium from nearby galaxies, newly observable with the Herschel SPIRE Fourier transform spectrometer, offer an opportunity to study warmer, more luminous molecular gas than that traced by 12CO J = 1 → 0. Here we present a survey of 17 nearby infrared-luminous galaxy systems (21 pointings). In addition to photometric modeling of dust, we modeled full 12CO spectral line energy distributions from J = 1 → 0 to J = 13 → 12 with two components of warm and cool CO gas, and included LTE analysis of [C I], [C II], [N II], and H2 lines. CO is emitted from a low-pressure/high-mass component traced by the low-J lines and a high-pressure/low-mass component that dominates the luminosity. We found that, on average, the ratios of the warm/cool pressure, mass, and 12CO luminosity are 60 ± 30, 0.11 ± 0.02, and 15.6 ± 2.7. The gas-to-dust-mass ratios are <120 throughout the sample. The 12CO luminosity is dominated by the high-J lines and is 4 × 10–4 L FIR on average. We discuss systematic effects of single-component and multi-component CO modeling (e.g., single-component J ≤ 3 models overestimate gas pressure by ∼0.5 dex), as well as compare to Galactic star-forming regions. With this comparison, we show the molecular interstellar medium of starburst galaxies is not simply an ensemble of Galactic-type giant molecular clouds. The warm gas emission is likely dominated by regions resembling the warm extended cloud of Sgr B2.

  14. A survey of the molecular ISM properties of nearby galaxies using the Herschel FTS

    Energy Technology Data Exchange (ETDEWEB)

    Kamenetzky, J. [Also at Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA. (United States); Rangwala, N. [Visiting Scientist, Space Science and Astrobiology Division, NASA Ames Research Center. (United States); Glenn, J.; Maloney, P. R.; Conley, A., E-mail: jkamenetzky@as.arizona.edu [Center for Astrophysics and Space Astronomy, University of Colorado at Boulder, 389-UCB, Boulder, CO (United States)

    2014-11-10

    The {sup 12}CO J = 4 → 3 to J = 13 → 12 lines of the interstellar medium from nearby galaxies, newly observable with the Herschel SPIRE Fourier transform spectrometer, offer an opportunity to study warmer, more luminous molecular gas than that traced by {sup 12}CO J = 1 → 0. Here we present a survey of 17 nearby infrared-luminous galaxy systems (21 pointings). In addition to photometric modeling of dust, we modeled full {sup 12}CO spectral line energy distributions from J = 1 → 0 to J = 13 → 12 with two components of warm and cool CO gas, and included LTE analysis of [C I], [C II], [N II], and H{sub 2} lines. CO is emitted from a low-pressure/high-mass component traced by the low-J lines and a high-pressure/low-mass component that dominates the luminosity. We found that, on average, the ratios of the warm/cool pressure, mass, and {sup 12}CO luminosity are 60 ± 30, 0.11 ± 0.02, and 15.6 ± 2.7. The gas-to-dust-mass ratios are <120 throughout the sample. The {sup 12}CO luminosity is dominated by the high-J lines and is 4 × 10{sup –4} L {sub FIR} on average. We discuss systematic effects of single-component and multi-component CO modeling (e.g., single-component J ≤ 3 models overestimate gas pressure by ∼0.5 dex), as well as compare to Galactic star-forming regions. With this comparison, we show the molecular interstellar medium of starburst galaxies is not simply an ensemble of Galactic-type giant molecular clouds. The warm gas emission is likely dominated by regions resembling the warm extended cloud of Sgr B2.

  15. A time domain experiment with Swift: monitoring of seven nearby galaxies

    Science.gov (United States)

    Andreoni, I.; D'Avanzo, P.; Campana, S.; Branchesi, M.; Bernardini, M. G.; Della Valle, M.; Mannucci, F.; Melandri, A.; Tagliaferri, G.

    2016-03-01

    Context. Focused on the study of transient sources, time domain astronomy today is one of the most active and growing areas of research in astronomy. Most of the present and planned surveys aimed at carrying out time domain studies work in the optical band and founded their searching strategies on fixed cadences. Although nothing similar currently exists in the X-ray and ultraviolet (UV) bands, the Swift satellite is certainly the most appropriate available instrument to carry out such surveys. Aims: We aimed to detect a supernova (SN) shock breakout (SBO) in nearby galaxies. The SBO marks the first escape of radiation from the blast wave that breaks through the photosphere of the star and launches the SN ejecta. The detection of an SBO is a diagnostic for the radius of the progenitor star and the ratio of explosion energy to ejecta mass. It also allows us to determine the onset of the explosion with an accuracy of a few hours to a few seconds. Methods: Using the XRT and UVOT instruments onboard the Swift satellite, we carried out a weekly cadenced, six-month monitoring of seven nearby galaxies: NGC 1084, NGC 2207/IC 2163, NGC 2770, NGC 4303/M 61, NGC 3147, NGC 3690, and NGC 6754. We searched for variable or transient sources in the collected data. These galaxies were selected because they are close (distance ≤50 Mpc), small enough to fit in the Swift/UVOT field of view, and are hosts of at least three SNe in the past 20 yr. Results: We found no evidence for an SN SBO event. Five objects located within the light of the sample galaxies were found to be variable in the X-ray and/or in the UV. These include mainly background active galactic nucleus and unresolved ULX in NGC 3690. In addition to these objects, we found two variable Galactic sources: the known nova CP Draconis (which experienced an outburst during our monitoring) and an uncatalogued eclipsing binary. Conclusions: Despite the lack of SBO detections, the results of our explorative study encourage the

  16. A Search for "Dwarf" Seyfert Nuclei; 5, Demographics of Nuclear Activity in Nearby Galaxies

    CERN Document Server

    Ho, L C; Sargent, W L W; Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W.

    1997-01-01

    We use the sample of emission-line nuclei derived from a recently completed optical spectroscopic survey of nearby galaxies to quantify the incidence of local (z = 0) nuclear activity. Consistent with previous studies, we find detectable amounts of ionized gas in the central few hundred parsecs of most (86%) galaxies. Half of the objects can be classified as H II or star-forming nuclei and the other half as some form of AGN, of which we distinguish three classes --- Seyfert nuclei, LINERs, and transition objects. The population of AGNs consequently is very large; approximately 43% of the galaxies in our survey can be regarded as "active." Most of the objects have much lower luminosities than AGNs commonly studied; the median luminosity of the narrow H-alpha line, after correcting for extinction, is only 2 x 10^39 erg/s. Our sample therefore occupies the extreme faint end of the AGN luminosity function. We detect signatures of a broad-line region, as revealed by visible broad H-alpha emission, in $\\sim$ 20% of...

  17. A time domain experiment with Swift: monitoring of seven nearby galaxies

    CERN Document Server

    Andreoni, Igor; Campana, Sergio; Branchesi, Marica; Bernardini, Maria Grazia; Della Valle, Massimo; Mannucci, Filippo; Melandri, Andrea; Tagliaferri, Gianpiero

    2016-01-01

    We aimed to detect a supernova (SN) shock breakout (SBO) with observations in time domain. The SBO marks the first escape of radiation from the blast wave that breaks through the photosphere of the star and launches the SN ejecta, and peaks in the ultraviolet and soft X-ray bands. The detection of a SBO allows determining the onset of the explosion with an accuracy from a few hours to a few seconds. Using the XRT and UVOT instruments onboard the Swift satellite we carried out a weekly cadenced, six months lasting monitoring of seven nearby (distance <50 Mpc) galaxies, namely NGC1084, NGC2207/IC2163, NGC2770, NGC4303/M61, NGC3147, NGC3690, NGC6754. We searched for variable/transient sources in the collected data. We found no evidence for a SN SBO event, but we discovered five objects located within the light of the sample galaxies that are variable in the X-ray and/or in the UV. Our sample galaxies are within the Universe volume that will be reached by the forthcoming advanced gravitational waves (GW) detec...

  18. Far-UV to mid-IR properties of nearby radio galaxies

    CERN Document Server

    de Ruiter, Hans R; Fanti, Roberto; Fanti, Carla

    2015-01-01

    We investigate whether the far-UV continuum of nearby radio galaxies reveals evidence for the presence of star forming or non-stellar components. If a UV excess due to an extra radiation component exists we compare this with other properties such as radio power, optical spectral type and the strength of the emission lines. We also discuss the possible correlation between the ultra-violet flux, IR properties and central black hole mass. We use two sampes of low luminosity radio galaxies with comparable redshifts ($z < 0.2$). Spectral Energy Distributions are constructed using a number of on-line databases: GALEX, SDSS, 2MASS, and WISE. The parameter $XUV$ is introduced, which measures the excess slope of the UV continuum between 4500 and 2000 \\AA, with respect to the UV radiation produced by the underlying old galaxy component. We find that the UV excess is usually small or absent in low luminosity sources, but sets in abruptly at the transition radio power above which we find mostly FRII sources. $XUV$ beh...

  19. The flaring HI disk of the nearby spiral galaxy NGC 2683

    CERN Document Server

    Vollmer, B; Ibata, R

    2015-01-01

    New deep VLA D array HI observations of the highly inclined nearby spiral galaxy NGC 2683 are presented. Archival C array data were processed and added to the new observations. To investigate the 3D structure of the atomic gas disk, we made different 3D models for which we produced model HI data cubes. The main ingredients of our best-fit model are (i) a thin disk inclined by 80 degrees; (ii) a crude approximation of a spiral and/or bar structure by an elliptical surface density distribution of the gas disk; (iii) a slight warp in inclination; (iv) an exponential flare; and (v) a low surface-density gas ring. The slope of NGC 2683's flare is comparable, but somewhat steeper than those of other spiral galaxies. NGC 2683's maximum height of the flare is also comparable to those of other galaxies. On the other hand, a saturation of the flare is only observed in NGC 2683. Based on the comparison between the high resolution model and observations, we exclude the existence of an extended atomic gas halo around the ...

  20. Distances to nearby galaxies combining fragmentary data using four different methods

    CERN Document Server

    Huterer, D; Schechter, P L; Huterer, Dragan; Sasselov, Dimitar D; Schechter, Paul L

    1995-01-01

    The primary distance indicators are established in our Galaxy and the Local Group. There are at least four different methods which give good distances: methods using proper motions, RR Lyraes, Cepheid variables, and Type II supernovae. However the data on independent distances is very fragmentary, due partly to nature and partly to technological limits. As a result the data are rarely put together in a consistent way; instead, the discussion of distance scales is often focused on one or two methods or on individual objects. Hence the question: what is the current situation with our overall knowledge of distances to the nearby galaxies? We try to answer this question by combining the fragmentary data from all four methods for fifteen objects: the galactic center, the globular clusters M2, M3, M4, M13, M22, M92, and 47 Tuc, the galaxies IC1613, M31, M33, M81, M100 and M101, and the Large Magellanic Cloud. We pay special attention to covariances among the different distance estimates. This most complete combinat...

  1. A search for HI absorption in nearby radio galaxies using HIPASS

    CERN Document Server

    Allison, J R; Meekin, A M

    2014-01-01

    Using archival data from the HI Parkes All Sky Survey (HIPASS) we have searched for 21 cm-line absorption in 204 nearby radio and star-forming galaxies with continuum flux densities greater than $S_{1.4} \\approx 250$ mJy within the redshift range $0 < cz < 12\\,000$ km s$^{-1}$. By applying a detection method based on Bayesian model comparison, we successfully detect and model absorption against the radio-loud nuclei of four galaxies, of which the Seyfert 2 galaxy 2MASX J130804201-2422581 was previously unknown. All four detections were achieved against compact radio sources, which include three active galactic nuclei (AGNs) and a nuclear starburst, exhibiting high dust and molecular gas content. Our results are consistent with the detection rate achieved by the recent ALFALFA HI absorption pilot survey by Darling et al. and we predict that the full ALFALFA survey should yield more than 3-4 times as many detections as we have achieved here. Furthermore, we predict that future all-sky surveys on the SKA p...

  2. The first time domain experiment with Swift: monitoring of seven nearby galaxies

    Science.gov (United States)

    Andreoni, I.; D’Avanzo, P.; Campana, S.; Branchesi, M.; Bernardini, MG; Delia Valle, M.; Mannucci, F.; Melandri, A.; Tagliaferri, G.

    2016-05-01

    We aimed to detect a supernova (SN) shock breakout (SBO) with observations in time domain. The SBO marks the first escape of radiation from the blast wave that breaks through the photosphere of the star and launches the SN ejecta, and peaks in the ultraviolet and soft X-ray bands. The detection of a SBO allows to determine the onset of the explosion with an accuracy from a few hours to a few seconds. Using the XRT and UVOT instruments onboard the Swift satellite we carried out a weekly cadenced, six months lasting monitoring of seven nearby (distance ≤ 50Mpc) galaxies, namely NGC1084, NGC2207/IC2163, NGC 2770, NGC4303/M61, NGC 3147, NGC 3690, NGC 6754. We searched for variable/transient sources in the collected data. We found no evidence for a SN SBO event, but we discovered five objects located within the light of the sample galaxies that are variable in the X-ray and/or in the UV. Our sample galaxies are within the Universe volume that will be reached by the forthcoming advanced gravitational waves (GW) detectors (a-LIGO/a-Virgo), thus this work provides an example on how to carry out Swift surveys useful to detect the GW signal from SNe, and to detect counterparts to GW triggers.

  3. Ultraluminous X-ray bursts in two ultracompact companions to nearby elliptical galaxies

    CERN Document Server

    Irwin, Jimmy A; Sivakoff, Gregory R; Romanowsky, Aaron J; Lin, Dacheng; Speegle, Tyler; Prado, Ian; Mildebrath, David; Strader, Jay; Liu, Jifeng; Miller, Jon M

    2016-01-01

    An X-ray flaring source was found near the galaxy NGC 4697. Two flares were seen, separated by four years. The flux increased by a factor of 90 on a timescale of about one minute. Both flares were very brief. There is no optical counterpart at the position of the flares, but if the source was at the distance of NGC 4697, the luminosities were 10^39 erg/s. Here we report the results of a search of archival X-ray data for 70 nearby galaxies looking for similar such flares. We found two flaring sources in globular clusters or ultra-compact dwarf companions of parent elliptical galaxies. One source flared once to a peak luminosity of 9 x 10^40 erg/s, while the other flared five times to 10^40 erg/s. All of the flare rise times were <1 minute, and they then decayed over about an hour. When not flaring, the sources appear to be normal accreting neutron star or black hole X-ray binaries, but they are located in old stellar populations, unlike the magnetars, anomalous X-ray pulsars or soft gamma repeaters that hav...

  4. HALOGAS: HI Observations and Modeling of the Nearby Edge-on Spiral Galaxy NGC 4565

    CERN Document Server

    Zschaechner, Laura K; Heald, George H; Gentile, Gianfranco; Jòzsa, Gyula

    2012-01-01

    We present 21-cm observations and models of the neutral hydrogen in NGC 4565, a nearby, edge-on spiral galaxy, as part of the Westerbork Hydrogen Accretion in LOcal GAlaxieS (HALOGAS) survey. These models provide insight concerning both the morphology and kinematics of HI above, as well as within, the disk. NGC 4565 exhibits a distinctly warped and asymmetric disk with a flaring layer. Our modeling provides no evidence for a massive, extended HI halo. We see evidence for a bar and associated radial motions. Additionally, there are indications of radial motions within the disk, possibly associated with a ring of higher density. We see a substantial decrease in rotational velocity with height above the plane of the disk (a lag) of -40 +5/-20 km/s/kpc and -30 +5/-30 km s/kpc in the approaching and receding halves, respectively. This lag is only seen within the inner ~4.75' (14.9 kpc) on the approaching half and ~4.25' (13.4 kpc) on the receding, making this a radially shallowing lag, which is now seen in the HI ...

  5. Calculation of Velocity Dispersion of the Nearby Galaxies Using Different Stellar Template Libraries

    Directory of Open Access Journals (Sweden)

    Lalovic, A.

    2010-06-01

    Full Text Available We present the central velocity dispersion measurements of the nearby galaxies from the Sloan Digital Sky Survey (SDSS. Using the sample from the paper by Ho et al. 2009, we have selected 23 galaxies for which we calculate the velocity dispersion. We have used the Penalized Pixel-Fitting code(Cappellari and Emsellem2004 to measure the velocity dispersion throughout the four chosen spectral regions: (3800,4568{AA}, (4568,5336{AA}, (5336,6104and (6104,6872{AA}. In all these regions, we have separately calculated dispersions and corresponding errors. We found that the measured values may vary with the change of spectral region, but, if weighted properly with the measure of the goodness of the fit, the final results will be shifted coloser to those for the best fitting regions. We have also tested how the use of different spectral libraries (Miles, Valdes and Elodie databases influences measurements and we showed that they do not affect measurements much. However, Elodie stellar library introduces the smallest errors in the velocity dispersion and it is the most stable throughout all four spectral regions. For these reasons it should be used preferentially when dealing with the SDSS spectra. We compare the results with the above mentioned paper and find a reasonable agreement. The agreement with the dispersions available in the HyperLeda database is very poor. The best agreement is obtained with SDSS measurements. We believe that our measurements are useful since SDSS velocity dispersions measurements are not available for many galaxies and the method of calculation of the velocity dispersion outlined in this work enables calculation of velocity dispersion for any galaxy. Of course, spectra with signal-to-noise ratio below 20 should be taken with caution.

  6. Galaxy Secular Mass Flow Rate Determination Using the Potential-Density Phase Shift Approach: Application to Six Nearby Spiral Galaxies

    CERN Document Server

    Zhang, Xiaolei

    2016-01-01

    Using the potential-density phase shift approach developed by the present authors in earlier publications, we estimate the magnitude of radial mass accretion/excretion rates across the disks of six nearby spiral galaxies having a range of Hubble types. Our goal is to examine these rates in the context of bulge building and secular morphological evolution along the Hubble sequence. Stellar surface density maps of the sample galaxies are derived from SINGS 3.6um and SDSS i-band images. Corresponding molecular and atomic gas surface densities are derived from published CO(1-0) and HI interferometric observations of the BIMA SONG, THINGS, and VIVA surveys. The mass flow rate calculations utilize a volume-type torque integral to calculate the angular momentum exchange rate between the basic state disk matter and density wave modes. The potential-density phase shift approach yields angular momentum transport rates several times higher than those estimated using the Lynden-Bell and Kalnajs (1972) approach. The curre...

  7. XMM-Newton observations of ultraluminous X-ray sources in nearby galaxies

    CERN Document Server

    Foschini, L; Ho, L C; Bassani, L; Cappi, M; Dadina, M; Gianotti, F; Malaguti, G; Panessa, F; Piconcelli, E; Stephen, J B; Trifoglio, M

    2002-01-01

    An XMM-Newton study of ultraluminous X-ray sources (ULX) has been performed in a sample of 10 nearby Seyfert galaxies. Eighteen ULX have been found with positional uncertainty of about 4". The large collecting area of XMM-Newton makes the statistics sufficient to perform spectral fitting with simple models in 8 cases. The main results of the present minisurvey strengthen the theory that the ULX could be accreting black holes in hard or soft state. In some cases, the contribution of the ULX to the overall X-ray flux appears to be dominant with respect to that of the active nucleus. In addition, 6 ULX present probable counterparts at other wavelengths (optical/infrared, radio). A multiwavelength observing strategy is required to better assess the nature of these sources.

  8. Halpha LEGUS: An Halpha Imaging Survey of Nearby Galaxies with HST

    Science.gov (United States)

    Lee, Janice C.; Chandar, Rupali; Krumholz, Mark R.; Thilker, David A.; Bright, Stacey N.; Halpha LEGUS

    2016-06-01

    We present first results from the Halpha LEGUS program, an HST narrowband survey of 30 nearby galaxies aimed at probing the relationship between young stars and the warm ionized interstellar medium (ISM). The superb resolution of HST enables the study of HII regions on the parsec scales where feedback from massive stellar populations is injected into the ISM. The span of the sample, which covers a large range in morphology, star formation rate, stellar mass, metallicity, and interaction state, allows for exploration of the possible dependencies of HII region evolution on galactic environment. We give an overview of the sample, observations, and initial characterization of HII region properties, all of which build on the foundation of HST NUV, U, B, V, I imaging obtained by the parent Legacy ExtraGalactic Ultraviolet Survey.

  9. Morphological studies of the galaxy populations in distant "Butcher-Oemler" clusters with HST. II. AC103, AC118 and AC114 at z=0.31

    CERN Document Server

    Couch, W J; Smail, I; Ellis, Richard S; Sharples, R M

    1997-01-01

    We present new results of a program to study the detailed morphologies of galaxies in intermediate redshift clusters and hence understand the physical origin of the enhanced star formation in these environments at earlier epochs. Deep, high resolution imagery has been obtained of 3 rich clusters, AC103,AC118 & AC114 at z=0.31, using the WFPC2 on HST. For AC103 & AC118, single pointings covering a central 0.5x0.5Mpc have been obtained; for AC114, 4 pointings covering a 1.2x0.7Mpc area have been obtained, allowing the more outer regions of a distant cluster to be studied. Hubble types plus evidence for dynamical interactions and/or structural abnormalities have been determined visually for all galaxies down to R=22.25 in AC103 & AC118 and R=23.0 in AC114.We find the numbers of spirals (Sa-Sdm) in our clusters to be up to 4x higher than that seen in present-day clusters; only in the virialised core of our most massive regular cluster, AC114, do we see morphological fractions approaching those of the ...

  10. Investigating the relation between CO (3-2) and far-infrared luminosities for nearby merging galaxies using ASTE

    Science.gov (United States)

    Michiyama, Tomonari; Iono, Daisuke; Nakanishi, Kouichiro; Ueda, Junko; Saito, Toshiki; Ando, Misaki; Kaneko, Hiroyuki; Yamashita, Takuji; Matsuda, Yuichi; Hatsukade, Bunyo; Kikuchi, Kenichi; Komugi, Shinya; Muto, Takayuki

    2016-09-01

    We present the new single-dish CO (3-2) emission data obtained toward 19 early-stage and 7 late-stage nearby merging galaxies using the Atacama Submillimeter Telescope Experiment (ASTE). Combining with the single-dish and interferometric data of galaxies observed in previous studies, we investigate the relation between the CO (3-2) luminosity (L^' }_CO(3-2)) and the far-infrared luminosity (LFIR) in a sample of 29 early-stage and 31 late-stage merging galaxies, and 28 nearby isolated spiral galaxies. We find that normal isolated spiral galaxies and merging galaxies have different slopes (α) in the log L^' }_CO(3-2)-log LFIR plane (α ˜ 0.79 for spirals and ˜1.12 for mergers). The large slope (α > 1) for merging galaxies can be interpreted as evidence for increasing star formation efficiency (SFE = L_FIR/L^' }_CO(3-2)) as a function of LFIR. Comparing our results with sub-kpc-scale local star formation and global starburst activity in the high-z universe, we find deviations from the linear relationship in the log L^' }_CO(3-2)-log LFIR plane for the late-stage mergers and high-z star-forming galaxies. Finally, we find that the average SFE gradually increases from isolated galaxies to merging galaxies and to high-z submillimeter galaxies/quasi-stellar objects. By comparing our findings with results from numerical simulations, we suggest that: (1) inefficient starbursts triggered by disk-wide dense clumps occur in the early stage of interaction, and (2) efficient starbursts triggered by central concentration of gas occur in the final stage. A systematic high spatial resolution survey of diffuse- and dense-gas tracers is the key to confirming this scenario.

  11. Dynamics of Nearby Groups of Galaxies: the role of the cosmological constant

    CERN Document Server

    Peirani, Sébastien

    2008-01-01

    (context) Different cosmological data are consistent with an accelerated expansion produced by an exotic matter-energy component, dubbed "dark-energy''. A cosmological constant is a possibility since it satisfies most of the observational constraints. (aims) In this work, the consequences of such a component in the dynamics of groups of galaxies is investigated, aiming to detect possible effects in scales of the order of few Mpc. (methods) The Lema\\^itre-Tolman model was modified by the inclusion of the cosmological constant term and, from the numerical solution of the equations of motion, a velocity-distance relation was obtained. This relation depends on two parameters: the central core mass and the Hubble parameter. The non-linear fit of such a relation to available data permitted to obtain masses for five nearby groups of galaxies and for the Virgo cluster as well as estimates of the Hubble constant. (results) The analysis of the present results indicates that the velocity-distance relation derived from t...

  12. Mapping the cold dust temperatures and masses of nearby Kingfish galaxies with Herschel

    CERN Document Server

    Galametz, M; Albrecht, M; Aniano, G; Armus, L; Bertoldi, F; Calzetti, D; Crocker, A F; Croxall, K V; Dale, D A; Meyer, J Donovan; Draine, B T; Engelbracht, C W; Hinz, J L; Roussel, H; Skibba, R A; Tabatabaei, F S; Walter, F; Weiss, A; Wilson, C D; Wolfire, M G

    2012-01-01

    Taking advantage of the sensitivity and angular resolution of the Herschel Space Observatory at far-infrared and submm wavelengths, we aim to characterize the physical properties of cold dust within nearby galaxies and study the robustness of the parameters we derive using different modified blackbody models. For a pilot subsample of the KINGFISH program, we perform 2 temperature fits of the Spitzer and Herschel photometric data (24 to 500um), with a warm and a cold component, globally and in each resolution element.At global scales, we observe ranges of values for beta_c(0.8 to 2.5) and Tc(19.1 to 25.1K).We compute maps of our parameters with beta fixed or free to test the robustness of the temperature and dust surface density maps we deduce. When the emissivity is fixed, we observe temperature gradients as a function of radius.When the emissivity is fitted as a free parameter, barred galaxies tend to have uniform fitted emissivities.Gathering resolved elements in a Tc-beta_c diagram underlines an anti-corre...

  13. Thick Disks, and an Outflow, of Dense Gas in the Nuclei of Nearby Seyfert Galaxies

    CERN Document Server

    Lin, Ming-Yi; Burtscher, L; Contursi, A; Genzel, R; González-Alfonso, E; Graciá-Carpio, J; Janssen, A; Lutz, D; de Xivry, G Orban; Rosario, D; Schnorr-Müller, A; Sternberg, A; Sturm, E; Tacconi, L

    2016-01-01

    We discuss the dense molecular gas in central regions of nearby Seyfert galaxies, and report new arcsec resolution observations of HCN(1-0) and HCO$^+$(1-0) for 3 objects. In NGC 3079 the lines show complex profiles as a result of self-absorption and saturated continuum absorption. H$^{13}$CN reveals the continuum absorption profile, with a peak close to the galaxy's systemic velocity that traces disk rotation, and a second feature with a blue wing extending to $-350$km s$^{-1}$ that most likely traces a nuclear outflow. The morphological and spectral properties of the emission lines allow us to constrain the dense gas dynamics. We combine our kinematic analysis for these 3 objects, as well as another with archival data, with a previous comparable analysis of 4 other objects, to create a sample of 8 Seyferts. In 7 of these, the emission line kinematics imply thick disk structures on radial scales of $\\sim$100pc, suggesting such structures are a common occurrence. We find a relation between the circumnuclear L...

  14. The Rise of SN 2014J in the Nearby Galaxy M 82

    Science.gov (United States)

    A.Goobar; Johansson, J.; Amanullah, R.; Cao, Y.; Perley, D.A.; Kasliwal, M. M.; Ferreti, R.; Nugent, P. E.; Harris, C.; Cenko, S. B.

    2014-01-01

    We report on the discovery of SN 2014J in the nearby galaxy M 82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova over a wide range of the electromagnetic spectrum. Optical, near-IR and mid-IR observations on the rising lightcurve, orchestrated by the intermediate Palomar Transient Factory (iPTF), show that SN 2014J is a spectroscopically normal Type Ia supernova, albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the lightcurve rise. Similarly to other highly reddened Type Ia supernovae, a low value of total-to-selective extinction, R (sub V) less than or approximately equal to 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from HST with special emphasis on the sources nearest to the SN location.

  15. Host Galaxy Properties and Hubble Residuals of Type Ia Supernovae from the Nearby Supernova Factory

    CERN Document Server

    Childress, M J; Antilogus, P; Aragon, C; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Cellier-Holzem, F; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Guy, J; Hsiao, E Y; Kerschhaggl, M; Kim, A G; Kowalski, M; Loken, S; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Runge, K; Scalzo, R; Smadja, G; Tao, C; Thomas, R C; Weaver, B A; Wu, C

    2013-01-01

    We examine the relationship between Type Ia Supernova (SN Ia) Hubble residuals and the properties of their host galaxies using a sample of 115 SNe Ia from the Nearby Supernova Factory (SNfactory). We use host galaxy stellar masses and specific star-formation rates fitted from photometry for all hosts, as well as gas-phase metallicities for a subset of 69 star-forming (non-AGN) hosts, to show that the SN Ia Hubble residuals correlate with each of these host properties. With these data we find new evidence for a correlation between SN Ia intrinsic color and host metallicity. When we combine our data with those of other published SN Ia surveys, we find the difference between mean SN Ia brightnesses in low and high mass hosts is 0.077 +- 0.014 mag. When viewed in narrow (0.2 dex) bins of host stellar mass, the data reveal apparent plateaus of Hubble residuals at high and low host masses with a rapid transition over a short mass range (9.8 <= log(M_*/M_Sun) <= 10.4). Although metallicity has been a favored i...

  16. [FeII] as a tracer of Supernova Rate in Near-by Starburst Galaxies

    CERN Document Server

    Rosenberg, M J F; Israel, F P

    2012-01-01

    Supernovae play an integral role in the feedback of processed material into the ISM of galaxies and are responsible for much of the chemical enrichment of the universe. The rate of supernovae can also reveal the star formation histories. Supernova rates are usually measured through the non-thermal radio continuum luminosity; however, a correlation between near-infrared [FeII] emission and supernova remnants has also been noted. We aim to find a quantitative relationship between the [FeII] at 1.26 um ([FeII]$_{1.26}$) luminosity and supernova rate in a sample of 11 near-by starburst galaxy centers. We perform a pixel-pixel analysis of this correlation on SINFONI data cubes. Using Br$\\gamma$ equivalent width and luminosity as the only observational inputs into the Starburst 99 model, we derive the supernova rate at each pixel and thus create maps of supernova rates. We then compare these morphologically and quantitatively to the [FeII]$_{1.26}$ luminosity. We have found that a strong linear and morphological co...

  17. Searching for hidden AGN in nearby star-forming galaxies with Chandra

    CERN Document Server

    Tzanavaris, P

    2007-01-01

    (ABRIDGED) AIMS: We searched for X-ray signatures of AGN in a sample of star-forming, relatively early-type, nearby spiral galaxies. Such galaxies are likely to host nuclear super-massive black holes. METHODS: For 9 sources from the Ho et al. optical sample, we isolated 10 individual Chandra X-ray sources closest to the optical position and calculated X-ray luminosities, Lx, X-ray colours, and, using Halpha luminosities, star formation rates. For 4 sources with sufficient counts, we extracted X-ray spectra and fitted standard spectral models. We assessed the significance of adding an Fe K alpha emission Gaussian component to a fit by means of a calibration of the standard F-test. For the rest of the sources, we estimated values for the intrinsic hydrogen column density, NHint, and the power-law photon index, Gamma, which can reproduce the observed X-ray colours. RESULTS: For the nuclear sources in NGC 2782 and NGC 3310, a Fe K alpha emission-line component is included with high significance, whilst the power-...

  18. Dense Gas in Nearby Galaxies XIV. Detection of hot ammonia in Maffei 2

    CERN Document Server

    Henkel, C; Peck, A B; Falcke, H; Hagiwara, Y

    2000-01-01

    The (J,K) = (1,1), (2,2), (3,3), and (4,4) inversion lines of ammonia (NH3) have been detected toward the nuclear 40'' sized bar of the nearby spiral galaxy Maffei 2. The relative intensities of the ammonia lines are characterized by a rotational temperature of 85 K. This is higher than rotational temperatures measured toward IC342 and most Galactic Center clouds, implying kinetic temperatures of at least 100 K. Since the kinetic temperature of the gas is larger than that of the dust, NH3 is tracing a particularly dense warm gas component that is heated by young massive stars, cloud-cloud collisions, or ion-slip heating in the nuclear starburst. The gas north of the nucleus (V(LSR} = -80 km/s) is more highly excited than the gas further south (+6 km/s). This asymmetry might be related to a pronounced morphological distortion that is observed in the north-eastern part of the galaxy.

  19. Dense gas in nearby galaxies XV. Hot ammonia in NGC253, Maffei2 and IC342

    CERN Document Server

    Mauersberger, R; Weiss, A; Peck, A B; Hagiwara, Y

    2003-01-01

    The detection of NH3 inversion lines up to the (J,K)=(6,6) level is reported toward the central regions of the nearby galaxies NGC253, Maffei2, and IC342. The observed lines are up to 406K (for (J,K)=(6,6)) and 848K (for the (9,9) transition) above the ground state and reveal a warm (T_kin= 100 - 140 K) molecular component toward all galaxies studied. The tentatively detected (J,K)=(9,9) line is evidence for an even warmer (>400K) component toward IC342. Toward NGC253, IC342 and Maffei2 the global beam averaged NH3 abundances are 1-2 10^-8, while the abundance relative to warm H2 is around 10^-7. The temperatures and NH3 abundances are similar to values found for the Galactic central region. C-shocks produced in cloud-cloud collisions can explain kinetic temperatures and chemical abundances. In the central region of M82, however, the NH3 emitting gas component is comparatively cool (~ 30K). It must be dense (to provide sufficient NH3 excitation) and well shielded from dissociating photons and comprises only a...

  20. The Young Stellar Population of the Nearby Late-Type Galaxy NGC 1311

    CERN Document Server

    Eskridge, Paul B; Mager, Violet A; Jansen, Rolf A

    2010-01-01

    We have extracted PSF-fitted stellar photometry from near-ultraviolet, optical and near-infrared images, obtained with the Hubble Space Telescope, of the nearby (D ~ 5.5 Mpc) SBm galaxy NGC 1311. The ultraviolet and optical data reveal a population of hot main sequence stars with ages of 2-10 Myr. We also find populations of blue supergiants with ages between 10 and 40 Myr and red supergiants with ages between 10 and 100 Myr. Our near-infrared data shows evidence of star formation going back ~1 Gyr, in agreement with previous work. Fits to isochrones indicate a metallicity of Z ~ 0.004. The ratio of blue to red supergiants is consistent with this metallicity. This indicates that NGC 1311 follows the well-known luminosity-metallicity relation for late-type dwarf galaxies. About half of the hot main sequence stars and blue supergiants are found in two regions in the inner part of NGC 1311. These two regions are each about 200 pc across, and thus have crossing times roughly equal to the 10 Myr age we find for th...

  1. The Emission by Dust and Stars of Nearby Galaxies in the Herschel KINGFISH Survey

    CERN Document Server

    Skibba, Ramin A; Dale, Daniel; Hinz, Joannah; Zibetti, Stefano; Crocker, Alison; Groves, Brent; Hunt, Leslie; Johnson, Benjamin D; Meidt, Sharon; Murphy, Eric J; Appleton, Philip; Armus, Lee; Bolatto, Alberto; Brandl, Bernhard; Calzetti, Daniela; Croxall, Kevin; Galametz, Maud; Gordon, Karl D; Kennicutt, Robert C; Koda, Jin; Krause, Oliver; Montiel, Edward; Rix, Hans-Walter; Roussel, Helene; Sandstrom, Karin; Sauvage, Marc; Schinnerer, Eva; Smith, J D; Walter, Fabian; Wilson, Christine D; Wolfire, Mark

    2011-01-01

    Using new far-infrared imaging from the Herschel Space Observatory with ancillary data from ultraviolet to submillimeter wavelengths, we estimate the total emission from dust and stars of 62 nearby galaxies in the KINGFISH survey in a way that is as empirical and model-independent as possible. We collect and exploit these data in order to measure from the spectral energy distributions (SEDs) precisely how much stellar radiation is intercepted and re-radiated by dust, and how this quantity varies with galaxy properties. By including SPIRE data, we are more sensitive to emission from cold dust grains than previous analyses at shorter wavelengths, allowing for more accurate estimates of dust temperatures and masses. The dust/stellar flux ratio, which we measure by integrating the SEDs, has a range of nearly three decades. The inclusion of SPIRE data shows that estimates based on data not reaching these far-IR wavelengths are biased low. We find that the dust/stellar flux ratio varies with morphology and total IR...

  2. Central Mass Profiles of the Nearby Cool-core Galaxy Clusters Hydra A and A478

    CERN Document Server

    Okabe, N; Tamura, T; Fujita, Y; Takizawa, M; Matsushita, K; Fukazawa, Y; Futamase, T; Kawaharada, M; Miyazaki, S; Mochizuki, Y; Nakazawa, K; Ohashi, T; Ota, N; Sasaki, T; Sato, K; Tam, S I

    2015-01-01

    We perform a weak-lensing study of the nearby cool-core galaxy clusters, Hydra A ($z=0.0538$) and A478 ($z=0.0881$), of which brightest cluster galaxies (BCGs) host powerful activities of active galactic nuclei (AGNs). For each cluster, the observed tangential shear profile is well described either by a single Navarro--Frenk--White model or a two-component model including the BCG as an unresolved point mass. For A478, we determine the BCG and its host-halo masses from a joint fit to weak-lensing and stellar photometry measurements. We find that the choice of initial mass functions (IMFs) can introduce a factor of two uncertainty in the BCG mass, whereas the BCG host halo mass is well constrained by data. We perform a joint analysis of weak-lensing and stellar kinematics data available for the Hydra A cluster, which allows us to constrain the central mass profile without assuming specific IMFs.We find that the central mass profile ($r<300$ kpc) determined from the joint analysis is in excellent agreement wi...

  3. Modelling CO emission from hydrodynamic simulations of nearby spirals, starbursting mergers, and high-redshift galaxies

    CERN Document Server

    Bournaud, F; Weiss, A; Renaud, F; Mastropietro, C; Teyssier, R

    2014-01-01

    We model the intensity of emission lines from the CO molecule, based on hydrodynamic simulations of spirals, mergers, and high-redshift galaxies with very high resolutions (3pc and 10^3 Msun) and detailed models for the phase-space structure of the interstellar gas including shock heating, stellar feedback processes and galactic winds. The simulations are analyzed with a Large Velocity Gradient (LVG) model to compute the local emission in various molecular lines in each resolution element, radiation transfer and opacity effects, and the intensity emerging from galaxies, to generate synthetic spectra for various transitions of the CO molecule. This model reproduces the known properties of CO spectra and CO-to-H2 conversion factors in nearby spirals and starbursting major mergers. The high excitation of CO lines in mergers is dominated by an excess of high-density gas, and the high turbulent velocities and compression that create this dense gas excess result in broad linewidths and low CO intensity-to-H2 mass r...

  4. Nearby early-type galaxies with ionized gas. The UV emission from GALEX observations

    CERN Document Server

    Marino, A; Bianchi, L; Annibali, F; Bressan, A; Buson, L M; Clemens, M S; Panuzzo, P; Zeilinger, W W

    2010-01-01

    We present GALEX far-ultraviolet (FUV, $\\lambda_{eff}$=1538 \\AA) and near-ultraviolet (NUV, $\\lambda_{eff}$=2316 \\AA) surface photometry of 40 early-type galaxies (ETGs) selected from a wider sample of 65 nearby ETGs showing emission lines in their optical spectra. We derive FUV and NUV surface brightness profiles, (FUV-NUV) colour profiles and D$_{25}$ integrated magnitudes. We extend the photometric study to the optical {\\it r} band from SDSS imaging for 14 of these ETGs. In general, the (FUV-NUV) radial colour profiles become redder with galactocentric distance in both rejuvenated ($\\leq 4$ Gyr) and old ETGs. Colour profiles of NGC 1533, NGC 2962, NGC 2974, NGC 3489, and IC 5063 show rings and/or arm-like structures, bluer than the body of the galaxy, suggesting the presence of recent star formation. Although seven of our ETGs show shell systems in their optical image, only NGC 7135 displays shells in the UV bands. We characterize the UV and optical surface brightness profiles, along the major axis, using ...

  5. Search for gas bulk motions in eight nearby clusters of galaxies with Suzaku

    CERN Document Server

    Ota, Naomi

    2015-01-01

    To search for bulk motions of the intracluster medium, we analyzed the X-ray spectra taken with the Suzaku satellite and measured the Doppler shift of Fe-K line emission from eight nearby clusters of galaxies with various X-ray morphologies. In the cores of the Centaurus and Perseus clusters, the gas bulk velocity does not exceed the sound velocity, which confirms the results of previous research. For the Cen45 subcluster, we found that the radial velocity relative to the Centaurus core, <780 km s^-1, is significantly smaller than that reported in the optical band at the 3.9 sigma level, which suggests an offset between the gas and galaxy distributions along the line of sight due to the subcluster merger. In A2199, A2142, A3667, and A133, no significant bulk motion was detected, indicating an upper limit on the radial velocity of 3000-4000 km s^-1. A sign of large bulk velocity in excess of the instrumental calibration uncertainty was found near the center of cool-core cluster A2029 and in the subcluster o...

  6. A Low-Mass Black Hole in the Nearby Seyfert Galaxy UGC 06728

    CERN Document Server

    Bentz, Misty C; Seals, James; Garcia, Karen; de Naray, Rachel Kuzio; Peters, Wesley; Anderson, Matthew D; Jones, Jeremy; Lester, Kathryn; Machuca, Camilo; Parks, J Robert; Pope, Crystal L; Revalski, Mitchell; Roberts, Caroline A; Saylor, Dicy; Sevrinsky, R Andrew; Turner, Clay

    2016-01-01

    We present the results of a recent reverberation mapping campaign for UGC 06728, a nearby low-luminosity Seyfert 1 in a late-type galaxy. Nightly monitoring in the spring of 2015 allowed us to determine an H$\\beta$ time delay of $\\tau = 1.4 \\pm 0.8$ days. Combined with the width of the variable H$\\beta$ line profile, we determine a black hole mass of $M_{\\rm BH} = (7.1 \\pm 4.0) \\times 10^5$ M$_{\\odot}$. We also constrain the bulge stellar velocity dispersion from higher-resolution long slit spectroscopy along the galaxy minor axis and find $\\sigma_{\\star} = 51.6 \\pm 4.9$ km s$^{-1}$. The measurements presented here are in good agreement with both the $R_{\\rm BLR} - L$ relationship and the $M_{\\rm BH}-\\sigma_{\\star}$ relationship for AGNs. Combined with a previously published spin measurement, our mass determination for UGC 06728 makes it the lowest-mass black hole that has been fully characterized, and thus an important object to help anchor the low-mass end of black hole evolutionary models.

  7. PACS photometry of the Herschel Reference Survey: far-infrared/submillimetre colours as tracers of dust properties in nearby galaxies

    OpenAIRE

    Cortese, L.; Fritz, Jacopo; S. Bianchi; Boselli, A.; Ciesla, L.; Bendo, GJ; Boquien, M.; Roussel, H.; Baes, Maarten; Buat, V.; Clemens, M.; Cooray, A.; Cormier, D.; Davies, JI; De Looze, Ilse

    2014-01-01

    We present Herschel/PACS 100 and 160 mu m integrated photometry for the 323 galaxies in the Herschel Reference Survey (HRS), a K-band, volume-limited sample of galaxies in the local Universe. Once combined with the Herschel/SPIRE observations already available, these data make the HRS the largest representative sample of nearby galaxies with homogeneous coverage across the 100-500 mu m wavelength range. In this paper, we take advantage of this unique data set to investigate the properties and...

  8. Optical observations of the nearby galaxy IC342 with narrow band [SII] and H$\\alpha$ filters. I

    CERN Document Server

    Vucetic, M M; Urosevic, D; Dobardzic, A; Pavlovic, M Z; Pannuti, T G; Petrov, N

    2013-01-01

    We present observations of the portion of the nearby spiral galaxy IC342 using narrow band [SII] and H$\\alpha$ filters. These observations were carried out in November 2011 with the 2m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper we report coordinates, diameters, H$\\alpha$ and [SII] fluxes for 203 HII regions detected in two fields of view in IC342 galaxy. The number of detected HII regions is 2.5 times higher than previously known in these two parts of the galaxy.

  9. Continuum Halos in Nearby Galaxies : An EVLA Survey (CHANG-ES). II. First Results on NGC 4631

    NARCIS (Netherlands)

    Irwin, Judith; Beck, Rainer; Benjamin, R. A.; Dettmar, Ralf-Jürgen; English, Jayanne; Heald, George; Henriksen, Richard N.; Johnson, Megan; Krause, Marita; Li, Jiang-Tao; Miskolczi, Arpad; Mora, Silvia Carolina; Murphy, E. J.; Oosterloo, Tom; Porter, Troy A.; Rand, Richard J.; Saikia, D. J.; Schmidt, Philip; Strong, A. W.; Walterbos, Rene; Wang, Q. Daniel; Wiegert, Theresa

    2012-01-01

    We present the first results from the Continuum Halos in Nearby Galaxies—an EVLA Survey (CHANG-ES), a new survey of 35 edge-on galaxies to search for both in-disk and extraplanar radio continuum emission. CHANG-ES is exploiting the new wide-band, multi-channel capabilities of the Karl G. Jansky Very

  10. FINDING {eta} CAR ANALOGS IN NEARBY GALAXIES USING SPITZER. I. CANDIDATE SELECTION

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Rubab; Stanek, K. Z.; Kochanek, C. S., E-mail: khan@astronomy.ohio-state.edu, E-mail: kstanek@astronomy.ohio-state.edu, E-mail: ckochanek@astronomy.ohio-state.edu [Department of Astronomy, The Ohio State University, 140 W. 18th Ave., Columbus, OH 43210 (United States)

    2013-04-10

    The late-stage evolution of the most massive stars such as {eta} Carinae is controlled by the effects of mass loss, which may be dominated by poorly understood eruptive mass ejections. Understanding this population is challenging because no true analogs of {eta} Car have been clearly identified in the Milky Way or other galaxies. We utilize Spitzer IRAC images of seven nearby ({approx}< 4 Mpc) galaxies to search for such analogs. We find 34 candidates with a flat or rising mid-IR spectral energy distributions toward longer mid-infrared wavelengths that emit >10{sup 5} L{sub Sun} in the IRAC bands (3.6 to 8.0 {mu}m) and are not known to be background sources. Based on our estimates for the expected number of background sources, we expect that follow-up observations will show that most of these candidates are not dust enshrouded massive stars, with an expectation of only 6 {+-} 6 surviving candidates. Since we would detect true analogs of {eta} Car for roughly 200 years post-eruption, this implies that the rate of eruptions like {eta} Car is less than the core-collapse supernova rate. It is possible, however, that every M > 40 M{sub Sun} star undergoes such eruptions given our initial results. In Paper II we will characterize the candidates through further analysis and follow-up observations, and there is no barrier to increasing the galaxy sample by an order of magnitude. The primary limitation of the present search is that Spitzer's resolution limits us to the shorter wavelength IRAC bands. With the James Webb Space Telescope, such surveys can be carried out at the far more optimal wavelengths of 10-30 {mu}m, allowing identification of {eta} Car analogs for millennia rather than centuries post-eruption.

  11. Investigating the Relation between CO (3-2) and Far Infrared Luminosities for Nearby Merging Galaxies Using ASTE

    CERN Document Server

    Michiyama, Tomonari; Nakanishi, Kouichiro; Ueda, Junko; Saito, Toshiki; Ando, Misaki; Kaneko, Hiroyuki; Yamashita, Takuji; Matsuda, Yuichi; Hatsukade, Bunyo; Kikuchi, Kenichi; Komugi, Shinya; Muto, Takayuki

    2016-01-01

    We present the new single dish CO (3-2) emission data obtained toward 19 early stage and 7 late stage nearby merging galaxies using the Atacama Submillimeter Telescope Experiment (ASTE). Combining with the single dish and interferometric data of galaxies observed in previous studies, we investigate the relation between the CO (3-2) luminosity (L'CO(3-2)) and the far Infrared luminosity (LFIR) in a sample of 29 early stage and 31 late stage merging galaxies, and 28 nearby isolated spiral galaxies. We find that normal isolated spiral galaxies and merging galaxies have different slopes (alpha) in the log L'CO(3-2) - log LFIR plane (alpha ~ 0.79 for spirals and ~ 1.12 for mergers). The large slope (alpha > 1) for merging galaxies can be interpreted as an evidence for increasing Star Formation Efficiency (SFE=LFIR/L'CO(3-2)) as a function of LFIR. Comparing our results with sub-kpc scale local star formation and global star-burst activity in the high-z Universe, we find deviations from the linear relationship in t...

  12. PACS photometry of the Herschel Reference Survey - far-infrared/submillimetre colours as tracers of dust properties in nearby galaxies

    Science.gov (United States)

    Cortese, L.; Fritz, J.; Bianchi, S.; Boselli, A.; Ciesla, L.; Bendo, G. J.; Boquien, M.; Roussel, H.; Baes, M.; Buat, V.; Clemens, M.; Cooray, A.; Cormier, D.; Davies, J. I.; De Looze, I.; Eales, S. A.; Fuller, C.; Hunt, L. K.; Madden, S.; Munoz-Mateos, J.; Pappalardo, C.; Pierini, D.; Rémy-Ruyer, A.; Sauvage, M.; di Serego Alighieri, S.; Smith, M. W. L.; Spinoglio, L.; Vaccari, M.; Vlahakis, C.

    2014-05-01

    We present Herschel/PACS 100 and 160 μm integrated photometry for the 323 galaxies in the Herschel Reference Survey (HRS), a K-band, volume-limited sample of galaxies in the local Universe. Once combined with the Herschel/SPIRE observations already available, these data make the HRS the largest representative sample of nearby galaxies with homogeneous coverage across the 100-500 μm wavelength range. In this paper, we take advantage of this unique data set to investigate the properties and shape of the far-infrared/submillimetre spectral energy distribution in nearby galaxies. We show that, in the stellar mass range covered by the HRS (8 ≲ log (M*/M⊙) ≲ 12), the far-infrared/submillimetre colours are inconsistent with a single modified blackbody having the same dust emissivity index β for all galaxies. In particular, either β decreases or multiple temperature components are needed, when moving from metal-rich/gas-poor to metal-poor/gas-rich galaxies. We thus investigate how the dust temperature and mass obtained from a single modified blackbody depend on the assumptions made on β. We show that, while the correlations between dust temperature, galaxy structure and star formation rate are strongly model dependent, the dust mass scaling relations are much more reliable, and variations of β only change the strength of the observed trends.

  13. Herschel Legacy Survey of Hydrogen Fluoride and Water Towards Nearby Galaxies

    Science.gov (United States)

    Rodriguez Monje, Raquel

    Hydride molecules, molecules containing just one heavy element atom with one or more hydrogen atoms, play an importance role in interstellar chemistry, as they are often stable end points of chemical reactions, or represent important intermediate stages of the reaction chains theorized to form gas phase molecules. This makes hydride molecules a sensitive test of these chemical models, as well as potential tracers of molecular hydrogen. Due to the low moment of inertia, hydrides have their fundamental rotational transitions in the submillimeter band, blocked by the Earth's atmosphere and in most cases, only accessible with the past NASA mission, Herschel Space Observatory. Two of the key results from Herschel observations are: the first detection of the fundamental J = 1 - 0 rotational transition of hydrogen fluoride (HF) at 1.232 THz (243 μm) and the discovery of HF's ubiquitous nature in the Milky Way. HF has not only been observed toward almost every bright continuum source in the Galactic plane, but also in some nearby ultra luminous galaxies, establishing its importance outside the Milky Way as well. Despite fluorine's (F) relative low abundance in the interstellar medium (ISM) (about four times lower than carbon), F plays an important role in the interstellar chemistry due to the unique thermochemistry of the reaction between F and molecular hydrogen (H2). F is the only atom that reacts exothermically with H2, to form the compound HF. Once formed, HF becomes the main reservoir of fluorine in the ISM, with a strong bond only destroyed by reactions with low abundance ions H3+, C+ and He+, or photodissociation. This unusual stability allows the build up of large amounts of HF in the ISM, which has now been confirmed by Herschel. Chemical model predicted that the ground state rotational transition line of HF J = 1 - 0 would yield an extremely sensitive probe of the diffuse molecular gas along the line-of-sight to background far-infrared continuum sources and a

  14. SUB-MILLIMETER TELESCOPE CO (2-1) OBSERVATIONS OF NEARBY STAR-FORMING GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xue-Jian; Gu, Qiusheng [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wang, Zhong [Harvard-Smithsonian Center for Astrophysics, MS 66, 60 Garden Street, Cambridge, MA 02138 (United States); Wang, Junzhi [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Zhang, Zhi-Yu, E-mail: xjjiang@nju.edu.cn [The UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom)

    2015-01-20

    We present CO J = 2-1 observations toward 32 nearby gas-rich star-forming galaxies selected from the ALFALFA and Wide-field Infrared Survey Explorer (WISE) catalogs, using the Sub-millimeter Telescope (SMT). Our sample is selected to be dominated by intermediate-M {sub *} galaxies. The scaling relations between molecular gas, atomic gas, and galactic properties (stellar mass, NUV – r, and WISE color W3 – W2) are examined and discussed. Our results show the following. (1) In the galaxies with stellar mass M {sub *} ≤10{sup 10} M {sub ☉}, the H I fraction (f {sub H} {sub I} ≡ M {sub H} {sub I}/M {sub *}) is significantly higher than that of more massive galaxies, while the H{sub 2} gas fraction (f{sub H{sub 2}} ≡ M{sub H{sub 2}}/M {sub *}) remains nearly unchanged. (2) Compared to f{sub H{sub 2}}, f {sub H} {sub I} correlates better with both M {sub *} and NUV – r. (3) A new parameter, WISE color W3 – W2 (12-4.6 μm), is introduced, which is similar to NUV – r in tracing star formation activity, and we find that W3 – W2 has a tighter anti-correlation with log f{sub H{sub 2}} than the anti-correlation of (NUV – r)-f {sub H} {sub I}, (NUV – r)-f{sub H{sub 2}}, and (W3 – W2)-f {sub H} {sub I}. This indicates that W3 – W2 can trace the H{sub 2} fraction in galaxies. For the gas ratio M{sub H{sub 2}}/M {sub H} {sub I} , only in the intermediate-M {sub *} galaxies it appears to depend on M {sub *} and NUV – r. We find a tight correlation between the molecular gas mass M{sub H{sub 2}} and 12 μm (W3) luminosities (L {sub 12} {sub μm}), and the slope is close to unity (1.03 ± 0.06) for the SMT sample. This correlation may reflect that the cold gas and dust are well mixed on a global galactic scale. Using the all-sky 12 μm (W3) data available in WISE, this correlation can be used to estimate CO flux for molecular gas observations and can even predict H{sub 2} mass for star-forming galaxies.

  15. The Heating of Mid-Infrared Dust in the Nearby Galaxy M33: A Testbed for Tracing Galaxy Evolution

    CERN Document Server

    Calapa, M; Draine, B T; Boquien, M; Kramer, C; Xilouris, M; Verley, S; Braine, J; Relaño-Pastor, M; van der Werf, P; Israel, F; Hermelo, I; Albrecht, M

    2014-01-01

    Because the 8 {\\mu}m polycyclic aromatic hydrocarbon (PAH) emission has been found to correlate with other well-known star formation tracers, it has widely been used as a star formation rate (SFR) tracer. There are, however, studies that challenge the accuracy and reliability of the 8 {\\mu}m emission as a SFR tracer. Our study, part of the Herschel M33 Extended Survey (HERM33ES) open time key program, aims at addressing this issue by analyzing the infrared emission from the nearby spiral galaxy M33 at the high spatial scale of 75 pc. Combining data from the Herschel Space Observatory and the Spitzer Space Telescope we find that the 8 {\\mu}m emission is better correlated with the 250 {\\mu}m emission, which traces cold interstellar gas, than with the 24 {\\mu}m emission. The L(8)/L(24) ratio is highly depressed in 24 {\\mu}m luminous regions, which correlate with known HII regions. We also compare our results with the dust emission models by Draine & Li (2007). We confirm that the depression of 8 {\\mu}m PAH e...

  16. Groups of Galaxies in the Nearby Universe Proceedings of the ESO Workshop held at Santiago de Chile

    CERN Document Server

    Saviane, Ivo; Borissova, Jordanka

    2007-01-01

    For every galaxy in the field or in clusters, there are about three galaxies in groups. The Milky Way itself resides in a group, and groups can be found at high redshift. The current generation of 10-m class telescopes and space facilities allows the observation of the members of nearby groups with exquisite detail, and their properties can be correlated with the global properties of their host group. Groups in the local Universe offer us the chance to study galaxies in environments characterized by strong interactions. In the cosmological context, groups trace large-scale structures better than clusters, and the evolution of groups and clusters appears to be related. All these aspects of research on groups of galaxies are summarized in this book written by scientists working in various fields.

  17. The flaring Hi disk of the nearby spiral galaxy NGC 2683

    Science.gov (United States)

    Vollmer, B.; Nehlig, F.; Ibata, R.

    2016-02-01

    New deep VLA D array Hi observations of the highly inclined nearby spiral galaxy NGC 2683 are presented. Archival C array data were processed and added to the new observations. To investigate the 3D structure of the atomic gas disk, we made different 3D models for which we produced model Hi data cubes. The main ingredients of our best-fit model are (i) a thin disk inclined by 80°; (ii) a crude approximation of a spiral and/or bar structure by an elliptical surface density distribution of the gas disk; (iii) a slight warp in inclination between 10 kpc ≤ R ≤ 20 kpc (decreasing by 10°); (iv) an exponential flare that rises from 0.5 kpc at R = 9 kpc to 4 kpc at R = 15 kpc, stays constant until R = 22 kpc, and decreases its height for R> 22 kpc; and (v) a low surface-density gas ring with a vertical offset of 1.3 kpc. The slope of NGC 2683's flare is comparable, but somewhat steeper than those of other spiral galaxies. NGC 2683's maximum height of the flare is also comparable to those of other galaxies. On the other hand, a saturation of the flare is only observed in NGC 2683. Based on the comparison between the high resolution model and observations, we exclude the existence of an extended atomic gas halo around the optical and thin gas disk. Under the assumption of vertical hydrostatic equilibrium we derive the vertical velocity dispersion of the gas. The high turbulent velocity dispersion in the flare can be explained by energy injection by (i) supernovae; (ii) magneto-rotational instabilities; (iii) interstellar medium stirring by dark matter substructure; or (iv) external gas accretion. The existence of the complex large-scale warping and asymmetries favors external gas accretion as one of the major energy sources that drives turbulence in the outer gas disk. We propose a scenario where this external accretion leads to turbulent adiabatic compression that enhances the turbulent velocity dispersion and might quench star formation in the outer gas disk of NGC

  18. Using Pulsars to Detect Massive Black Hole Binaries via Gravitational Radiation Sagittarius A* and Nearby Galaxies

    CERN Document Server

    Lommen, A N; Lommen, Andrea N.; Backer, Donald C.

    2001-01-01

    Pulsar timing measurements can be used to detect gravitational radiation from massive black hole binaries. The ~106d quasi-periodic flux variations in Sagittarius A* at radio wavelengths reported by Zhao, Bower, & Goss (2001) may be due to binarity of the massive black hole that is presumed to be responsible for the radio emission. A 106d equal-mass binary black hole is unlikely based on its short inspiral lifetime and other arguments. Nevertheless the reported quasi-periodicity has led us to consider whether the long-wavelength gravitational waves from a conjectured binary might be detected in present or future precision timing of millisecond pulsars. While present timing cannot reach the level expected for an equal-mass binary, we estimate that future efforts could. This inquiry has led us to further consider the detection of binarity in the massive black holes now being found in nearby galaxies. For orbital periods of ~2000d where the pulsar timing measurements are most precise, we place upper limits o...

  19. Hydrogen Fluoride toward Luminous Nearby Galaxies: NGC 253 and NGC 4945

    CERN Document Server

    Monje, R R; Falgarone, E; Lis, D C; Neufeld, D A; Phillips, T G; Güsten, R

    2014-01-01

    We present the detection of hydrogen fluoride, HF, in two luminous nearby galaxies NGC 253 and NGC 4945 using the Heterodyne Instrument for the Far-Infrared (HIFI) on board the Herschel Space Observatory. The HF line toward NGC 253 has a P-Cygni profile, while an asymmetric absorption profile is seen toward NGC 4945. The P-Cygni profile in NGC 253 suggests an outflow of molecular gas with a mass of M(H$_2$)$_{out}$ $\\sim$ 1 $\\times$ 10$^7$ M$_\\odot$ and an outflow rate as large as \\.{M} $\\sim$ 6.4 M$_\\odot$ yr$^{-1}$. In the case of NGC 4945, the axisymmetric velocity components in the HF line profile is compatible with the interpretation of a fast-rotating nuclear ring surrounding the nucleus and the presence of inflowing gas. The gas falls into the nucleus with an inflow rate of $\\le$ 1.2 M$_\\odot$ yr$^{-1}$, inside a inner radius of $\\le$ 200 pc. The gas accretion rate to the central AGN is much smaller, suggesting that the inflow can be triggering a nuclear starburst. From these results, the HF $J = 1-0$ ...

  20. Infrared 3-4 Micron Spectroscopic Investigations of a Large Sample of Nearby Ultraluminous Infrared Galaxies

    CERN Document Server

    Imanishi, M; Maloney, P R; Imanishi, Masatoshi; Maloney, Philip R.

    2006-01-01

    We present infrared L-band (3-4 micron) nuclear spectra of a large sample of nearby ultraluminous infrared galaxies (ULIRGs).ULIRGs classified optically as non-Seyferts (LINERs, HII-regions, and unclassified) are our main targets. Using the 3.3 micron polycyclic aromatic hydrocarbon (PAH) emission and absorption features at 3.1 micron due to ice-covered dust and at 3.4 micron produced by bare carbonaceous dust, we search for signatures of powerful active galactic nuclei (AGNs) deeply buried along virtually all lines-of-sight. The 3.3 micron PAH emission, the signatures of starbursts, is detected in all but two non-Seyfert ULIRGs, but the estimated starburst magnitudes can account for only a small fraction of the infrared luminosities. Three LINER ULIRGs show spectra typical of almost pure buried AGNs, namely, strong absorption features with very small equivalent-width PAH emission. Besides these three sources, 14 LINER and 3 HII ULIRGs' nuclei show strong absorption features whose absolute optical depths sugg...

  1. ALMA Multi-line Imaging of the Nearby Starburst Galaxy NGC 253

    CERN Document Server

    Meier, David S; Bolatto, Alberto D; Leroy, Adam K; Ott, Jürgen; Rosolowsky, Erik; Veilleux, Sylvain; Warren, Steven R; Weiss, Axel; Zwaan, Martin A; Zschaechner, Laura K

    2015-01-01

    We present spatially resolved ($\\sim$50 pc) imaging of molecular gas species in the central kiloparsec of the nearby starburst galaxy NGC 253, based on observations taken with the Atacama Large Millimeter/submillimeter Array (ALMA). A total of 50 molecular lines are detected over a 13 GHz bandwidth imaged in the 3 mm band. Unambiguous identifications are assigned for 27 lines. Based on the measured high CO/C$^{17}$O isotopic line ratio ($\\gtrsim$350), we show that $^{12}$CO(1-0) has moderate optical depths. A comparison of the HCN and HCO$^{+}$ with their $^{13}$C-substituted isotopologues shows that the HCN(1-0) and HCO$^{+}$(1-0) lines have optical depths at least comparable to CO(1-0). H$^{13}$CN/H$^{13}$CO$^{+}$ (and H$^{13}$CN/HN$^{13}$C) line ratios provide tighter constraints on dense gas properties in this starburst. SiO has elevated abundances across the nucleus. HNCO has the most distinctive morphology of all the bright lines, with its global luminosity dominated by the outer parts of the central re...

  2. Spatially Resolved Chemistry in Nearby Galaxies I. The Center of IC 342

    CERN Document Server

    Meier, D S; Meier, David S.; Turner, Jean L.

    2004-01-01

    We have imaged emission from the millimeter lines of eight molecules--C2H, C34S, N2H+, CH3OH, HNCO, HNC, HC3N, and SO--in the central half kpc of the nearby spiral galaxy IC 342. The 5" (~50 pc) resolution images were made with OVRO. Using these maps we obtain a picture of the chemistry within the nuclear region on the sizescales of individual GMCs. Bright emission is detected from all but SO. There are marked differences in morphology for the different molecules. A principal component analysis is performed to quantify similarities and differences among the images. This analysis reveals that while all molecules are to zeroth order correlated, that is, they are all found in dense molecular clouds, there are three distinct groups of molecules distinguished by the location of their emission within the nuclear region. N2H+, C18O, HNC and HCN are widespread and bright, good overall tracers of dense molecular gas. C2H and C34S, tracers of PDR chemistry, originate exclusively from the central 50-100 pc region, where...

  3. Discovery of Five Candidate Analogs for $\\eta\\,$Carinae in Nearby Galaxies

    CERN Document Server

    Khan, Rubab; Stanek, K Z; Kochanek, C S; Sonneborn, G

    2015-01-01

    The late-stage evolution of very massive stars such as $\\eta\\,$Carinae may be dominated by poorly understood episodic mass ejections which may later lead to superluminous supernovae. However, as long as $\\eta\\,$Car is one of a kind, it is nearly impossible to quantitatively evaluate these possibilities. Here we announce the discovery of five objects in the nearby ($\\sim4-8\\,$Mpc) massive star-forming galaxies M$51$, M$83$, M$101$ and NGC$6946$ that have optical through mid-infrared photometric properties consistent with the hitherto unique $\\eta\\,$Car. We identified these $L_{bol}\\simeq3-8\\times10^{6}\\,L_\\odot$ objects through a systematic search of archival Spitzer and HST data. Their Spitzer mid-infrared spectral energy distributions rise steeply in the $3.6-8\\,\\mu$m bands, then turn over between $8$ and $24\\,\\mu$m, indicating the presence of warm ($\\sim400-600\\,$K) circumstellar dust. Their optical counterparts or flux limits from deep HST images are $\\sim1.5-2\\,$dex fainter than their mid-IR peaks and req...

  4. Herschel-SPIRE-Fourier Transform Spectroscopy of the nearby spiral galaxy IC342

    CERN Document Server

    Rigopoulou, D; Swinyard, B M; Virdee, J; Croxall, K V; Hopwood, R H B; Lim, T; Magdis, G E; Pearson, C P; Pellegrini, E; Polehampton, E; Smith, J-D

    2013-01-01

    We present observations of the nearby spiral galaxy IC342 with the Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer. The spectral range afforded by SPIRE, 196-671 microns, allows us to access a number of 12CO lines from J=4--3 to J=13--12 with the highest J transitions observed for the first time. In addition we present measurements of 13CO, [CI] and [NII]. We use a radiative transfer code coupled with Bayesian likelihood analysis to model and constrain the temperature, density and column density of the gas. We find two 12CO components, one at 35 K and one at 400 K with CO column densities of 6.3x10^{17} cm^{-2} and 0.4x10^{17} cm^{-2} and CO gas masses of 1.26x10^{7} Msolar and 0.15x10^{7} Msolar, for the cold and warm components, respectively. The inclusion of the high-J 12CO line observations, indicate the existence of a much warmer gas component (~400 K) confirming earlier findings from H_{2} rotational line analysis from ISO and Spitzer. The mass of the warm gas i...

  5. Nearby supernova host galaxies from the CALIFA Survey: II. SN environmental metallicity

    CERN Document Server

    Galbany, L; Mourão, A M; Rodrigues, M; Flores, H; Walcher, C J; Sánchez, S F; García-Benito, R; Mast, D; Badenes, C; Delgado, R M González; Kehrig, C; Lyubenova, M; Marino, R A; Mollá, M; Meidt, S; Pérez, E; van de Ven, G; Vílchez, J M

    2016-01-01

    The metallicity of a supernova (SN) progenitor, together with its mass, is one of the main parameters that rules their outcome. We present a metallicity study of 115 nearby SN host galaxies (0.00510 dex) by targeted searches. We also found no evidence that the metallicity at the SN location differs from the average metallicity at the GCD of the SNe. By extending our SN sample with published metallicities at the SN location, we studied the metallicity distributions for all SN subtypes split into SN discovered in targeted and untargeted searches. We confirm a bias toward higher host masses and metallicities in the targeted searches. Combining data from targeted and untargeted searches we found a sequence from higher to lower local metallicity: SN Ia, Ic, and II show the highest metallicity, which is significantly higher than SN Ib, IIb, and Ic-BL. Our results support the picture of SN Ib resulting from binary progenitors and, at least part of, SN Ic being the result of single massive stars stripped of their out...

  6. The Star Formation Efficiency in Nearby Galaxies: Measuring Where Gas Forms Stars Effectively

    CERN Document Server

    Leroy, Adam K; Brinks, Elias; Bigiel, Frank; De Blok, W J G; Madore, Barry; Thornley, M D

    2008-01-01

    We measure the star formation efficiency (SFE), the star formation rate per unit gas, in 23 nearby galaxies and compare it to expectations from proposed star formation laws and thresholds. We use HI maps from THINGS and derive H2 maps from HERACLES and BIMA SONG CO. We estimate the star formation rate by combining GALEX FUV maps and SINGS 24 micron maps, infer stellar surface density profiles from SINGS 3.6 micron data, and use kinematics from THINGS. We measure the SFE as a function of: the free-fall and orbital timescales; midplane gas pressure; stability of the gas disk to collapse (including the effects of stars); the ability of perturbations to grow despite shear; and the ability of a cold phase to form. In spirals, the SFE of H2 alone is nearly constant at 5.25 +/- 2.5 x 10^(-10) yr^(-1) (equivalent to an H2 depletion time of 1.9x10^9 yr) as a function of all of these variables at our 800 pc resolution. Where the ISM is mostly HI, on the other hand, the SFE decreases with increasing radius in both spira...

  7. Ultraviolet to Infrared SED (Spectral Energy Distribution) Analysis of Nearby Late-Stage Merging Galaxies Using CIGALE

    Science.gov (United States)

    Weiner, Aaron; Ashby, Matthew; Martinez-Galarza, Juan Rafael; Hayward, Christopher C.; Hung, Chao-Ling; Lanz, Lauranne; Rosenthal, Lee; Smith, Howard Alan; Willner, Steven P.; Zezas, Andreas

    2016-01-01

    We present an analysis of the fundamental properties of nearby merging galaxies based on in-depth analysis of their spectral energy distributions. Our new sample, which is based on the catalog of nearby merging galaxies from the SIGS sample (Spitzer Interacting Galaxy Sample; Lanz et al. 2013, 2014), cross-correlates the Revised IRAC-FSC Redshift Catalogue (Wang et al. 2014) with Galaxy Zoo, which builds on and extends the previous investigation by Lanz et al. in two ways. First it enlarges the sample considerably, increasing the statistical power of the analysis significantly. Second, it includes galaxies in the most advanced merger stage, filling a potential gap in the Lanz et al. sample. The cross-correlation gave 453 possible mergers, between 400 and 453 of which are interacting on some level. After more clearly defining the evolutionary stages of the merging process, these galaxies' stages were identified morphologically, and selected according to brightness () and stage (late stages 4-6), more than tripling the total late-stage sample to about 40 or 50 systems, 16 of which have sufficient observational data for a full SED analysis. These, along with the late-stage mergers found in the SIGS sample, have been photometered from the ultraviolet (UV) to the far-infrared (FIR) and subsequently fit and analyzed by the newly revised and updated CIGALE (Code Investigating Galaxy Emission; Burgarella et al. 2005) in order to retrieve key physical properties of the galaxies including star-formation rate (SFR), AGN fraction, and stellar and dust mass, as well as identify any trends in terms of shape and physical properties of spectra within the evolutionary range of late-stage mergers.

  8. Tracing the evolution of nearby early-type galaxies in low density environments. The Ultraviolet view from GALEX

    CERN Document Server

    Rampazzo, R; Marino, A; Bianchi, L; Bressan, A; Buson, L M; Clemens, M; Panuzzo, P; Zeilinger, W W; 10.1007/s10509-010-0586-5

    2011-01-01

    We detected recent star formation in nearby early-type galaxies located in low density environments, with GALEX Ultraviolet (UV) imaging. Signatures of star formation may be present in the nucleus and in outer rings/arm like structures. Our study suggests that such star formation may be induced by different triggering mechanisms, such as the inner secular evolution driven by bars, and minor accretion phenomena. We investigate the nature of the (FUV-NUV) color vs. Mg2 correlation, and suggest that it relates to "downsizing" in galaxy formation.

  9. Searching for X-ray sources in nearby late-type galaxies with low star formation rates

    CERN Document Server

    Chatterjee, K; Brorby, M; Kajava, J J E; Grise, F; Farrell, S; Poutanen, J

    2015-01-01

    Late type non-starburst galaxies have been shown to contain X-ray emitting objects, some being ultraluminous X-ray sources. We report on XMM-Newton observations of 11 nearby, late-type galaxies previously observed with the Hubble Space Telescope (HST) in order to find such objects. We found 18 X-ray sources in or near the optical extent of the galaxies, most being point-like. If associated with the corresponding galaxies, the source luminosities range from $2 \\times 10^{37}$ erg s$^{-1}$ to $6 \\times 10^{39}$ erg s$^{-1}$. We found one ultraluminous X-ray source, which is in the galaxy IC 5052, and one source coincident with the galaxy IC 4662 with a blackbody temperature of $0.166 \\pm 0.015$ keV that could be a quasi-soft source or a quiescent neutron star X-ray binary in the Milky Way. One X-ray source, XMMU J205206.0$-$691316, is extended and coincident with a galaxy cluster visible on an HST image. The X-ray spectrum of the cluster reveals a redshift of $z = 0.25 \\pm 0.02$ and a temperature of 3.6$\\pm$0.4...

  10. Searching for X-ray sources in nearby late-type galaxies with low-star formation rates

    Science.gov (United States)

    Chatterjee, K.; Kaaret, P.; Brorby, M.; Kajava, J. J. E.; Grisé, F.; Farrell, S.; Poutanen, J.

    2016-03-01

    Late-type non-starburst galaxies have been shown to contain X-ray emitting objects, some being ultraluminous X-ray sources. We report on XMM-Newton observations of 11 nearby, late-type galaxies previously observed with the Hubble Space Telescope (HST) in order to find such objects. We found 18 X-ray sources in or near the optical extent of the galaxies, most being point-like. If associated with the corresponding galaxies, the source luminosities range from 2 × 1037 erg s-1 to 6 × 1039 erg s-1. We found one ultraluminous X-ray source, which is in the galaxy IC 5052, and one source coincident with the galaxy IC 4662 with a blackbody temperature of 0.166 ± 0.015 keV that could be a quasi-soft source or a quiescent neutron star X-ray binary in the Milky Way. One X-ray source, XMMU J205206.0-691316, is extended and coincident with a galaxy cluster visible on an HST image. The X-ray spectrum of the cluster reveals a redshift of z = 0.25 ± 0.02 and a temperature of 3.6±0.4 keV. The redshift was mainly determined by a cluster of Fe XXIV lines between the observed energy range 0.8 - 1.0 keV.

  11. THE HST/ACS COMA CLUSTER SURVEY. VIII. BARRED DISK GALAXIES IN THE CORE OF THE COMA CLUSTER

    Energy Technology Data Exchange (ETDEWEB)

    Marinova, Irina; Jogee, Shardha; Weinzirl, Tim [Department of Astronomy, University of Texas at Austin, Austin, TX (United States); Erwin, Peter [Max-Planck-Insitut fuer extraterrestrische Physik, Giessenbachstrasse, 85748 Garching (Germany); Trentham, Neil [Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Ferguson, Henry C.; Goudfrooij, Paul [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Hammer, Derek [Department of Physics and Astronomy, Johns Hopkins, Baltimore, MD 21218 (United States); Den Brok, Mark; Peletier, Reynier F.; Kleijn, Gijs V. [Kapteyn Astronomical Institute, University of Groningen, Groningen (Netherlands); Graham, Alister W. [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn (Australia); Carter, David; Mouhcine, Mustapha [Astrophysics Research Institute, Liverpool John Moores University, Birkenhead (United Kingdom); Balcells, Marc [Instituto de Astrofisica de Canarias, 38200 La Laguna, Tenerife (Spain); Guzman, Rafael; Hoyos, Carlos [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Peng, Eric W., E-mail: marinova@astro.as.utexas.edu, E-mail: sj@astro.as.utexas.edu [Department of Astronomy, Peking University, Beijing 100871 (China)

    2012-02-20

    We use high-resolution ({approx}0.''1) F814W Advanced Camera for Surveys (ACS) images from the Hubble Space Telescope ACS Treasury survey of the Coma cluster at z {approx} 0.02 to study bars in massive disk galaxies (S0s), as well as low-mass dwarf galaxies in the core of the Coma cluster, the densest environment in the nearby universe. Our study helps to constrain the evolution of bars and disks in dense environments and provides a comparison point for studies in lower density environments and at higher redshifts. Our results are: (1) we characterize the fraction and properties of bars in a sample of 32 bright (M{sub V} {approx}< -18, M{sub *} > 10{sup 9.5} M{sub Sun }) S0 galaxies, which dominate the population of massive disk galaxies in the Coma core. We find that the measurement of a bar fraction among S0 galaxies must be handled with special care due to the difficulty in separating unbarred S0s from ellipticals, and the potential dilution of the bar signature by light from a relatively large, bright bulge. The results depend sensitively on the method used: the bar fraction for bright S0s in the Coma core is 50% {+-} 11%, 65% {+-} 11%, and 60% {+-} 11% based on three methods of bar detection, namely, strict ellipse fit criteria, relaxed ellipse fit criteria, and visual classification. (2) We compare the S0 bar fraction across different environments (the Coma core, A901/902, and Virgo) adopting the critical step of using matched samples and matched methods in order to ensure robust comparisons. We find that the bar fraction among bright S0 galaxies does not show a statistically significant variation (within the error bars of {+-}11%) across environments which span two orders of magnitude in galaxy number density (n {approx} 300-10,000 galaxies Mpc{sup -3}) and include rich and poor clusters, such as the core of Coma, the A901/902 cluster, and Virgo. We speculate that the bar fraction among S0s is not significantly enhanced in rich clusters compared to

  12. THE HST/ACS COMA CLUSTER SURVEY. VIII. BARRED DISK GALAXIES IN THE CORE OF THE COMA CLUSTER

    International Nuclear Information System (INIS)

    We use high-resolution (∼0.''1) F814W Advanced Camera for Surveys (ACS) images from the Hubble Space Telescope ACS Treasury survey of the Coma cluster at z ∼ 0.02 to study bars in massive disk galaxies (S0s), as well as low-mass dwarf galaxies in the core of the Coma cluster, the densest environment in the nearby universe. Our study helps to constrain the evolution of bars and disks in dense environments and provides a comparison point for studies in lower density environments and at higher redshifts. Our results are: (1) we characterize the fraction and properties of bars in a sample of 32 bright (MV ∼* > 109.5 M☉) S0 galaxies, which dominate the population of massive disk galaxies in the Coma core. We find that the measurement of a bar fraction among S0 galaxies must be handled with special care due to the difficulty in separating unbarred S0s from ellipticals, and the potential dilution of the bar signature by light from a relatively large, bright bulge. The results depend sensitively on the method used: the bar fraction for bright S0s in the Coma core is 50% ± 11%, 65% ± 11%, and 60% ± 11% based on three methods of bar detection, namely, strict ellipse fit criteria, relaxed ellipse fit criteria, and visual classification. (2) We compare the S0 bar fraction across different environments (the Coma core, A901/902, and Virgo) adopting the critical step of using matched samples and matched methods in order to ensure robust comparisons. We find that the bar fraction among bright S0 galaxies does not show a statistically significant variation (within the error bars of ±11%) across environments which span two orders of magnitude in galaxy number density (n ∼ 300-10,000 galaxies Mpc–3) and include rich and poor clusters, such as the core of Coma, the A901/902 cluster, and Virgo. We speculate that the bar fraction among S0s is not significantly enhanced in rich clusters compared to low-density environments for two reasons. First, S0s in rich clusters are

  13. Probing dark matter decay and annihilation with Fermi LAT observations of nearby galaxy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiaoyuan [Chinese Academy of Sciences, Beijing (China). National Astronomical Observatories; Max-Planck-Institut fuer Physik, Muenchen (Germany); Vertongen, Gilles [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Institut d' Astrophysique de Paris, 75 - Paris (France); Weniger, Christoph [Max-Planck-Institut fuer Physik, Muenchen (Germany)

    2011-09-15

    Galaxy clusters are promising targets for indirect dark matter searches. Gamma-ray signatures from the decay or annihilation of dark matter particles inside these clusters could be observable with the Fermi Large Area Telescope (LAT). Based on three years of Fermi LAT gamma-ray data, we analyze the flux coming from eight nearby clusters individually as well as in a combined likelihood analysis. Concentrating mostly on signals from dark matter decay, we take into account uncertainties of the cluster masses as determined by X-ray observations and model the cluster emission with extended sources. We do not find significant emission from any of the considered clusters and present limits on the dark matter lifetime and annihilation cross-section. We compare our lifetime limits derived from cluster observations with the limits that can be obtained from the extragalactic gamma-ray background, and find that in case of hadronic decay the cluster limits become competitive at dark matter masses below a few hundred GeV. Finally, we show that in presence of dark matter substructures down to 10{sup -6} solar masses the limits on the dark matter annihilation cross-section could improve by a factor of a few hundred, possibly going down to the thermal cross-section of 3 x 10{sup -26} cm{sup 3}s{sup -1} for dark matter masses

  14. Near-infrared spectroscopy of nearby Seyfert galaxies: Is there evidence for the shock excitation in narrow-line regions?

    CERN Document Server

    Terao, Koki; Hashimoto, Tetsuya; Yanagisawa, Kenshi; Matsuoka, Kenta; Toba, Yoshiki; Ikeda, Hiroyuki; Taniguchi, Yoshiaki

    2016-01-01

    One of the unsettled, important problems in active galactic nuclei (AGNs) is the major ionization mechanism of gas clouds in their narrow-line regions (NLRs). In order to investigate this issue, we present our $J$-band spectroscopic observations for a sample of 26 nearby Seyfert galaxies. In our study, we use the flux ratio of the following two forbidden emission lines, [Fe II]1.257$\\mu$m and [P II]1.188$\\mu$m because it is known that this ratio is sensitive to the ionization mechanism. We obtain the [Fe II]/[P II] flux ratio or its lower limit for 19 objects. In addition to our data, we compile this flux ratio (or its lower limit) of 23 nearby Seyfert galaxies from the literature. Based on the collected data, we find that three Seyfert galaxies show very large lower limits of [Fe II]/[P II] flux ratios ($\\gtrsim$10); NGC 2782, 5005, and Mrk 463. It is thus suggested that the contribution of the fast shock in the gas excitation is significantly large for them. However, more than half of Seyfert galaxies in ou...

  15. The VIRUS-P Exploration of Nearby Galaxies (VENGA): Survey Design, Data Processing, and Spectral Analysis Methods

    CERN Document Server

    Blanc, Guillermo A; Song, Mimi; Heiderman, Amanda; Gebhardt, Karl; Jogee, Shardha; Evans, Neal J; Bosch, Remco C E van den; Luo, Rongxin; Drory, Niv; Fabricius, Maximilian; Fisher, David; Hao, Lei; Kaplan, Kyle; Marinova, Irina; Vutisalchavakul, Nalin; Yoachim, Peter

    2013-01-01

    We present the survey design, data reduction, and spectral fitting pipeline for the VIRUS-P Exploration of Nearby Galaxies (VENGA). VENGA is an integral field spectroscopic survey, which maps the disks of 30 nearby spiral galaxies. Targets span a wide range in Hubble type, star formation activity, morphology, and inclination. The VENGA data-cubes have 5.6'' FWHM spatial resolution, ~5A FWHM spectral resolution, sample the 3600A-6800A range, and cover large areas typically sampling galaxies out to ~0.7 R_25. These data-cubes can be used to produce 2D maps of the star formation rate, dust extinction, electron density, stellar population parameters, the kinematics and chemical abundances of both stars and ionized gas, and other physical quantities derived from the fitting of the stellar spectrum and the measurement of nebular emission lines. To exemplify our methods and the quality of the data, we present the VENGA data-cube on the face-on Sc galaxy NGC 628 (a.k.a. M 74). The VENGA observations of NGC 628 are de...

  16. Extragalactic archeology with the GHOSTS Survey I. - Age-resolved disk structure of nearby low-mass galaxies

    CERN Document Server

    Streich, David; Bailin, Jeremy; Bell, Eric F; Holwerda, Benne W; Minchev, Ivan; Monachesi, Antonela; Radburn-Smith, David J

    2016-01-01

    We study the individual evolution histories of three nearby low-mass edge-on galaxies (IC 5052, NGC4244, and NGC5023). Using resolved stellar populations, we constructed star count density maps for populations of different ages and analyzed the change of structural parameters with stellar age within each galaxy. We do not detect a separate thick disk in any of the three galaxies, even though our observations cover a wider range in equivalent surface brightness than any integrated light study. While scale heights increase with age, each population can be well described by a single disk. Two of the galaxies contain a very weak additional component, which we identify as the faint halo. The mass of these faint halos is lower than 1% of the mass of the disk. The three galaxies show low vertical heating rates, which are much lower than the heating rate of the Milky Way. This indicates that heating agents, such as giant molecular clouds and spiral structure, are weak in low-mass galaxies. All populations in the thre...

  17. Box/Peanut and Bar structures in edge-on and face-on SDSS nearby galaxies I. Catalogue

    CERN Document Server

    Yoshino, Akira

    2014-01-01

    We investigate Box/Peanut and bar structures in image data of edge-on and face-on nearby galaxies taken from SDSS (Sloan Digital Sky Survey) to present catalogues containing the surface brightness parameters and the morphology classification. About 1700 edge-on galaxies and 2600 face-on galaxies are selected from SDSS DR7 in g, r and i-band. The images of each galaxy are fitted with the model of 2-dimensional surface brightness of S\\'{e}rsic bulge and exponential disk. After removing some irregular data, Box/Peanut, bar and other structures are easily distinguished by eye using residual (observed minus model) images. We find 292 Box/Peanut structures in the 1329 edge-on samples and 630 bar structures in 1890 face-on samples in i-band, after removing some irregular data. Then the fraction of Box/Peanut galaxies is about 22 percent against the edge-on samples, and that of bar is about 33 percent (about 50 percent if 629 elliptical galaxies are removed) against the face-on samples. Furthermore the strengths of t...

  18. The search for active black holes in nearby low-mass galaxies using optical and mid-IR data

    CERN Document Server

    Sartori, Lia F; Treister, Ezequiel; Trakhtenbrot, Benny; Koss, Michael; Shirazi, Maryam; Oh, Kyuseok

    2015-01-01

    We investigated AGN activity in low-mass galaxies, an important regime that can shed light onto BH formation and evolution, and their interaction with their host galaxies. We identified 336 AGN candidates from a parent sample of $\\sim 48,000$ nearby low-mass galaxies ($M_{\\rm \\star} \\leq 10^{9.5}M_\\odot$, $z < 0.1$) in the SDSS. We selected the AGN using the classical BPT diagram, a similar optical emission line diagnostic based on the HeII$\\lambda$4686 line, and mid-IR color cuts. Different criteria select host galaxies with different physical properties such as stellar mass and optical color, and only 3 out of 336 sources fulfill all three criteria. This could be in part due to selection biases. The resulting AGN fraction of $\\sim 0.7 \\%$ is at least one order of magnitude below the one estimated for more massive galaxies. At optical wavelengths, the HeII-based AGN selection appears to be more sensitive to AGN hosted in star-forming galaxies than the classical BPT diagram, at least in the low-mass regime...

  19. Spatially Resolved Stellar Populations Of Nearby Post-Starburst Galaxies In SDSS-IV MaNGA

    Science.gov (United States)

    Liu, Charles; Betances, Ashley; Bonilla, Alaina Marie; Gonzalez, Andrea; Migliore, Christina; Goddard, Daniel; Masters, Karen; SDSS-IV MaNGA Team

    2016-01-01

    We have selected five galaxies in the Mapping Nearby Galaxies at APO (MaNGA) project of the latest generation of the Sloan Digital Sky Survey (SDSS-IV) identified as post-starburst (E+A) systems, in the transition between "blue cloud" and "red sequence" galaxies. We measure the equivalent widths of the Balmer series, D4000 break, and metal lines across each galaxy, and produce maps of the stellar age, stellar mass, and metallicities of each galaxy using FIREFLY, a full spectral analysis code. We have found that the measured properties of the galaxies overall generally matches well with single-aperture SDSS spectra from which the original post-starburst identifications were made. The variation in the spatial distributions of the stellar populations, in particular the A-stars, give us insight into the details of the transitional E+A quenching phase. This work was supported by the Alfred P. Sloan Foundation via the SDSS-IV Faculty and Student Team (FAST) initiative, ARC Agreement No. SSP483 to the CUNY College of Staten Island.

  20. Where are the nearby gas-rich low surface brightness galaxies?

    NARCIS (Netherlands)

    Briggs, FH

    1997-01-01

    The Fisher-Tully (F-T) ''10 Mpc Catalog of Late-Type Galaxies'' is remarkably complete. Despite the considerable effort that has been spent searching for and cataloging low surface brightness (LSB) galaxies, almost no new HI-rich galaxies have been added to the volume to which the F-T observations w

  1. OVERVIEW OF THE SDSS-IV MaNGA SURVEY: MAPPING NEARBY GALAXIES AT APACHE POINT OBSERVATORY

    Energy Technology Data Exchange (ETDEWEB)

    Bundy, Kevin [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwa 277-8583 (Japan); Bershady, Matthew A.; Wake, David A.; Tremonti, Christy; Diamond-Stanic, Aleksandar M. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Law, David R.; Cherinka, Brian [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); Yan, Renbin; Sánchez-Gallego, José R. [Department of Physics and Astronomy, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055 (United States); Drory, Niv [McDonald Observatory, Department of Astronomy, University of Texas at Austin, 1 University Station, Austin, TX 78712-0259 (United States); MacDonald, Nicholas [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Weijmans, Anne-Marie [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Thomas, Daniel; Masters, Karen; Coccato, Lodovico [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth (United Kingdom); Aragón-Salamanca, Alfonso [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Avila-Reese, Vladimir [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A.P. 70-264, 04510 Mexico D.F. (Mexico); Badenes, Carles [Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 OHara St, Pittsburgh, PA 15260 (United States); Falcón-Barroso, Jésus [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Belfiore, Francesco [Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); and others

    2015-01-01

    We present an overview of a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV) that began on 2014 July 1. MaNGA will investigate the internal kinematic structure and composition of gas and stars in an unprecedented sample of 10,000 nearby galaxies. We summarize essential characteristics of the instrument and survey design in the context of MaNGA's key science goals and present prototype observations to demonstrate MaNGA's scientific potential. MaNGA employs dithered observations with 17 fiber-bundle integral field units that vary in diameter from 12'' (19 fibers) to 32'' (127 fibers). Two dual-channel spectrographs provide simultaneous wavelength coverage over 3600-10300 Å at R ∼ 2000. With a typical integration time of 3 hr, MaNGA reaches a target r-band signal-to-noise ratio of 4-8 (Å{sup –1} per 2'' fiber) at 23 AB mag arcsec{sup –2}, which is typical for the outskirts of MaNGA galaxies. Targets are selected with M {sub *} ≳ 10{sup 9} M {sub ☉} using SDSS-I redshifts and i-band luminosity to achieve uniform radial coverage in terms of the effective radius, an approximately flat distribution in stellar mass, and a sample spanning a wide range of environments. Analysis of our prototype observations demonstrates MaNGA's ability to probe gas ionization, shed light on recent star formation and quenching, enable dynamical modeling, decompose constituent components, and map the composition of stellar populations. MaNGA's spatially resolved spectra will enable an unprecedented study of the astrophysics of nearby galaxies in the coming 6 yr.

  2. Overview of the SDSS-IV MaNGA Survey: Mapping nearby Galaxies at Apache Point Observatory

    Science.gov (United States)

    Bundy, Kevin; Bershady, Matthew A.; Law, David R.; Yan, Renbin; Drory, Niv; MacDonald, Nicholas; Wake, David A.; Cherinka, Brian; Sánchez-Gallego, José R.; Weijmans, Anne-Marie; Thomas, Daniel; Tremonti, Christy; Masters, Karen; Coccato, Lodovico; Diamond-Stanic, Aleksandar M.; Aragón-Salamanca, Alfonso; Avila-Reese, Vladimir; Badenes, Carles; Falcón-Barroso, Jésus; Belfiore, Francesco; Bizyaev, Dmitry; Blanc, Guillermo A.; Bland-Hawthorn, Joss; Blanton, Michael R.; Brownstein, Joel R.; Byler, Nell; Cappellari, Michele; Conroy, Charlie; Dutton, Aaron A.; Emsellem, Eric; Etherington, James; Frinchaboy, Peter M.; Fu, Hai; Gunn, James E.; Harding, Paul; Johnston, Evelyn J.; Kauffmann, Guinevere; Kinemuchi, Karen; Klaene, Mark A.; Knapen, Johan H.; Leauthaud, Alexie; Li, Cheng; Lin, Lihwai; Maiolino, Roberto; Malanushenko, Viktor; Malanushenko, Elena; Mao, Shude; Maraston, Claudia; McDermid, Richard M.; Merrifield, Michael R.; Nichol, Robert C.; Oravetz, Daniel; Pan, Kaike; Parejko, John K.; Sanchez, Sebastian F.; Schlegel, David; Simmons, Audrey; Steele, Oliver; Steinmetz, Matthias; Thanjavur, Karun; Thompson, Benjamin A.; Tinker, Jeremy L.; van den Bosch, Remco C. E.; Westfall, Kyle B.; Wilkinson, David; Wright, Shelley; Xiao, Ting; Zhang, Kai

    2015-01-01

    We present an overview of a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV) that began on 2014 July 1. MaNGA will investigate the internal kinematic structure and composition of gas and stars in an unprecedented sample of 10,000 nearby galaxies. We summarize essential characteristics of the instrument and survey design in the context of MaNGA's key science goals and present prototype observations to demonstrate MaNGA's scientific potential. MaNGA employs dithered observations with 17 fiber-bundle integral field units that vary in diameter from 12'' (19 fibers) to 32'' (127 fibers). Two dual-channel spectrographs provide simultaneous wavelength coverage over 3600-10300 Å at R ~ 2000. With a typical integration time of 3 hr, MaNGA reaches a target r-band signal-to-noise ratio of 4-8 (Å-1 per 2'' fiber) at 23 AB mag arcsec-2, which is typical for the outskirts of MaNGA galaxies. Targets are selected with M * >~ 109 M ⊙ using SDSS-I redshifts and i-band luminosity to achieve uniform radial coverage in terms of the effective radius, an approximately flat distribution in stellar mass, and a sample spanning a wide range of environments. Analysis of our prototype observations demonstrates MaNGA's ability to probe gas ionization, shed light on recent star formation and quenching, enable dynamical modeling, decompose constituent components, and map the composition of stellar populations. MaNGA's spatially resolved spectra will enable an unprecedented study of the astrophysics of nearby galaxies in the coming 6 yr.

  3. HST/ACS Photometry of Old Stars in NGC 1569: The Star Formation History of a Nearby Starburst

    CERN Document Server

    Grocholski, Aaron J; Aloisi, Alessandra; Annibali, Francesca; Greggio, Laura; Tosi, Monica

    2012-01-01

    (abridged) We used HST/ACS to obtain deep V- and I-band images of NGC 1569, one of the closest and strongest starburst galaxies in the Universe. These data allowed us to study the underlying old stellar population, aimed at understanding NGC 1569's evolution over a full Hubble time. We focus on the less-crowded outer region of the galaxy, for which the color-magnitude diagram (CMD) shows predominantly a red giant branch (RGB) that reaches down to the red clump/horizontal branch feature (RC/HB). A simple stellar population analysis gives clear evidence for a more complicated star formation history (SFH) in the outer region. We derive the full SFH using a newly developed code, SFHMATRIX, which fits the CMD Hess diagram by solving a non-negative least squares problem. Our analysis shows that the relative brightnesses of the RGB tip and RC/HB, along with the curvature and color of the RGB, provide enough information to ameliorate the age-metallicity-extinction degeneracy. The distance/reddening combination that b...

  4. The Green Bank Telescope Maps the Dense, Star-Forming Gas in the Nearby Starburst Galaxy M82

    CERN Document Server

    Kepley, Amanda A; Frayer, David; Usero, Antonio; Marvil, Josh; Walter, Fabian

    2013-01-01

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO+. Here we demonstrate the power of the Robert C. Byrd Green Bank Telescope -- the largest single-dish millimeter radio telescope -- for mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN and HCO+ in the starburst galaxy M82. The HCN and HCO+ in the disk of this galaxy correlates with both recent star formation and more diffuse molecular gas and shows kinematics consistent with a rotating torus. The HCO+ emission extending to the north and south of the disk is coincident with the outflow previously identified in CO and...

  5. Sleeping Giants? - X-ray search for low-luminosity AGN candidates in nearby optically bright galaxies

    CERN Document Server

    Kalcheva, Ivayla E

    2014-01-01

    In this Master's project, the X-ray nuclear properties of a sample of bright nearby galaxies are explored. This is done by matching their comprehensive optical spectroscopic classification to the latest available XMM-Newton catalogue - 3XMM-DR4. The good coverage (approx. 38 per cent) ensures that a statistically representative sample is investigated. All nuclear and morphological subsets found within the original sample of 486 galaxies are encompassed, but early-type galaxies and galaxies with optical features characteristic for active galactic nuclei (AGN) are favoured. The results from the investigation of the properties of our cross-matched sample are overall consistent with the presence of a large fraction of X-ray - detected low-luminosity AGN (LLAGN). The X-ray - detected galaxies within our HII and transition-LINER subsets are of particular interest, as they could harbour LLAGN missed by optical spectroscopic selection. The properties of these nuclei are explored by X-ray spectral fitting of available...

  6. XMM-NEWTON OBSERVATIONS OF LUMINOUS SOURCES IN NEARBY GALAXIES NGC 4395, NGC 4736, AND NGC 4258

    Energy Technology Data Exchange (ETDEWEB)

    Akyuz, A.; Avdan, H. [Department of Physics, University of Cukurova, 01330 Adana (Turkey); Kayaci, S. [Department of Astronomy, University of Erciyes, Kayseri (Turkey); Ozel, M. E. [Faculty of Arts and Sciences, Cag University, 33800 Yenice, Tarsus, Mersin (Turkey); Sonbas, E. [Department of Physics, University of Ad Latin-Small-Letter-Dotless-I yaman, 02040 Ad Latin-Small-Letter-Dotless-I yaman (Turkey); Balman, S., E-mail: aakyuz@cu.edu.tr [Department of Physics, Middle East Technical University, 06531 Ankara (Turkey)

    2013-03-15

    We present the results of a study of non-nuclear discrete sources in a sample of three nearby spiral galaxies (NGC 4395, NGC 4736, and NGC 4258) based on XMM-Newton archival data supplemented with Chandra data for spectral and timing analyses. A total of 75 X-ray sources have been detected within the D{sub 25} regions of the target galaxies. The large collecting area of XMM-Newton makes the statistics sufficient to obtain spectral fitting for 16 (about 20%) of these sources. Compiling the extensive archival exposures available, we were able to obtain the detailed spectral shapes of diverse classes of point sources. We have also studied temporal properties of these luminous sources. Eleven of them are found to show short-term (less than 80 ks) variation while eight of them show long-term variation within factors of {approx}2-5 during a time interval of {approx}2-12 years. Timing analysis provides strong evidence that most of these sources are accreting X-ray binary systems. One source that has properties different from others was suspected to be a supernova remnant, and our follow-up optical observation confirmed this. Our results indicate that sources within the three nearby galaxies are showing a variety of source populations, including several ultraluminous X-ray sources, X-ray binaries, transients together with a super soft source, and a background active galactic nucleus candidate.

  7. Extragalactic Planetary Nebulae: tracers of the chemical evolution of nearby galaxies

    OpenAIRE

    Magrini, Laura; Stanghellini, Letizia; Goncalves, Denise R.

    2011-01-01

    The study of the chemical composition of Planetary Nebulae in external galaxies is of paramount importance in the fields of stellar evolution and of the chemical enrichment history of galaxies. In the last years a number of spectroscopic studies with 6-8m-class telescopes have been devoted to this subject improving our knowledge of, among other, the time-evolution of the radial metallicity gradient in disk galaxies, the chemical evolution of dwarf galaxies, and the stellar evolution at low me...

  8. The discovery of seven extremely low surface brightness galaxies in the field of the nearby spiral galaxy M101

    CERN Document Server

    Merritt, Allison; Abraham, Roberto

    2014-01-01

    Dwarf satellite galaxies are a key probe of dark matter and of galaxy formation on small scales and of the dark matter halo masses of their central galaxies. They have very low surface brightness, which makes it difficult to identify and study them outside of the Local Group. We used a low surface brightness-optimized telescope, the Dragonfly Telephoto Array, to search for dwarf galaxies in the field of the massive spiral galaxy M101. We identify seven large, low surface brightness objects in this field, with effective radii of \\(10 - 30\\) arcseconds and central surface brightnesses of \\(\\mu_{g} \\sim 25.5 - 27.5\\) mag arcsec\\(^{-2}\\). Given their large apparent sizes and low surface brightnesses, these objects would likely be missed by standard galaxy searches in deep fields. Assuming the galaxies are dwarf satellites of M101, their absolute magnitudes are in the range \\(-11.6 \\lesssim M_{V} \\lesssim -9.3\\) and their effective radii are \\(350\\) pc \\(-\\) \\(1.3\\) kpc. Their radial surface brightness profiles ar...

  9. The Sloan Lens ACS Survey. VII. Elliptical galaxy scaling laws from direct observational mass measurements

    NARCIS (Netherlands)

    Bolton, Adam S.; Treu, Tommaso; Koopmans, Leon V. E.; Gavazzi, Raphael; Moustakas, Leonidas A.; Burles, Scott; Schlegel, David J.; Wayth, Randall

    2008-01-01

    We use a sample of 53 massive early-type strong gravitational lens galaxies with well-measured redshifts (ranging from z = 0.06 to 0.36) and stellar velocity dispersions (between 175 and 400 km s(-1)) from the Sloan Lens ACS (SLACS) Survey to derive numerous empirical scaling relations. The ratio be

  10. HST/ACS Direct Ages of the Dwarf Elliptical Galaxies NGC 147 and NGC 185

    CERN Document Server

    Geha, M; Grocholski, A; Dolphin, A; van der Marel, R P; Guhathakurta, P

    2015-01-01

    We present the deepest optical photometry for any dwarf elliptical (dE) galaxy based on Hubble Space Telescope ACS observations of the Local Group dE galaxies NGC 147 and NGC 185. The resulting F606W and F814W color-magnitude diagrams are the first to reach below the main sequence turnoff in a dE galaxy, allowing us to determine full star formation histories in these systems. The ACS fields are located ~1.5 effective radii from the galaxy center to avoid photometric crowding. While our ACS pointings in both dEs show unambiguous evidence for old and intermediate age stars, the mean age in NGC 147 is ~ 4 Gyr younger as compared to NGC 185. In NGC 147, only 40% of stars were in place 12.5 Gyrs ago (z~5), with the bulk of the remaining stellar population forming between 5 to 7 Gyr. In contrast, 70% of stars were formed in NGC 185 field more than12.5 Gyr ago with the majority of the remaining population forming between 8 to 10 Gyr. Star formation ceased in both ACS fields at least 3 Gyr ago. Previous observations ...

  11. An extensive catalogue of early-type galaxies in the nearby universe

    CERN Document Server

    Dabringhausen, J

    2016-01-01

    We present a catalogue of 1715 early-type galaxies from the literature, spanning the luminosity range from faint dwarf spheroidal galaxies to giant elliptical galaxies. The aim of this catalogue is to be one of the most comprehensive and publicly available collections of data on early-type galaxies. The emphasis in this catalogue lies on dwarf elliptical galaxies, for which some samples with detailed data have been published recently. For almost all of the early-type galaxies included in it, this catalogue contains data on their locations, distances, redshifts, half-light radii, the masses of their stellar populations and apparent magnitudes in various passbands. Data on metallicity and various colours are available for a majority of the galaxies presented here, including many of the rather faint early-type galaxies in the Local group. The data on magnitudes, colours, metallicities and masses of the stellar populations is supplemented with entries that are based on fits to data from simple stellar population ...

  12. An extensive catalogue of early-type galaxies in the nearby Universe

    Science.gov (United States)

    Dabringhausen, J.; Fellhauer, M.

    2016-08-01

    We present a catalogue of 1715 early-type galaxies from the literature, spanning the luminosity range from faint dwarf spheroidal galaxies to giant elliptical galaxies. The aim of this catalogue is to be one of the most comprehensive and publicly available collections of data on early-type galaxies. The emphasis in this catalogue lies on dwarf elliptical galaxies, for which some samples with detailed data have been published recently. For almost all of the early-type galaxies included in it, this catalogue contains data on their locations, distances, redshifts, half-light radii, the masses of their stellar populations and apparent magnitudes in various passbands. Data on metallicity and various colours are available for a majority of the galaxies presented here. The data on magnitudes, colours, metallicities and masses of the stellar populations are supplemented with entries that are based on fits to data from simple stellar population models and existing data from observations. Also, some simple transformations have been applied to the data on magnitudes, colours and metallicities in this catalogue, in order to increase the homogeneity of these data. Estimates on the Sérsic profiles, internal velocity dispersions, maximum rotational velocities, dynamical masses and ages are listed for several hundreds of the galaxies in this catalogue. Finally, each quantity listed in this catalogue is accompanied with information on its source, so that users of this catalogue can easily exclude data that they do not consider as reliable enough for their purposes.

  13. VizieR Online Data Catalog: Nearby early-type galaxies catalog (Dabringhausen+, 2016)

    Science.gov (United States)

    Dabringhausen, J.; Fellhauer, M.

    2016-06-01

    We present a catalogue of 1715 early-type galaxies from the literature, spanning the luminosity range from faint dwarf spheroidal galaxies to giant elliptical galaxies. The aim of this catalogue is to be one of the most comprehensive and publicly available collections of data on early-type galaxies. The emphasis in this catalogue lies on dwarf elliptical galaxies, for which some samples with detailed data have been published recently. For almost all of the early-type galaxies included in it, this catalogue contains data on their locations, distances, redshifts, half-light radii, the masses of their stellar populations and apparent magnitudes in various passbands. Data on metallicity and various colours are available for a majority of the galaxies presented here. The data on magnitudes, colours, metallicities and masses of the stellar populations is supplemented with entries that are based on fits to data from simple stellar population models and existing data from observations. Also, some simple transformations have been applied to the data on magnitudes, colours and metallicities in this catalog, in order to increase the homogeneity of this data. Estimates on the Sersic profiles, internal velocity dispersions, maximum rotational velocities, dynamical masses and ages are listed for several hundreds of the galaxies in this catalogue. Finally, each quantity listed in this catalogue is accompanied with information on its source, so that users of this catalogue can easily exclude data that they do not consider as reliable enough for their purposes. (10 data files).

  14. The Local Group as a time machine: studying the high-redshift Universe with nearby galaxies

    CERN Document Server

    Boylan-Kolchin, Michael; Johnson, Benjamin D; Bullock, James S; Conroy, Charlie; Fitts, Alex

    2015-01-01

    We infer the UV luminosities of Local Group galaxies at early cosmic times ($z \\sim 2$ and $z \\sim 7$) by combining stellar population synthesis modeling with star formation histories derived from deep color-magnitude diagrams constructed from Hubble Space Telescope (HST) observations. Our analysis provides a basis for understanding high-$z$ galaxies - including those that may be unobservable even with the James Webb Space Telescope (JWST) - in the context of familiar, well-studied objects in the very low-$z$ Universe. We find that, at the epoch of reionization, all Local Group dwarfs were less luminous than the faintest galaxies detectable in deep HST observations of blank fields. We predict that JWST will observe $z \\sim 7$ progenitors of galaxies similar to the Large Magellanic Cloud today; however, the HST Frontier Fields initiative may already be observing such galaxies, highlighting the power of gravitational lensing. Consensus reionization models require an extrapolation of the observed blank-field lum...

  15. Chandra survey of nearby highly inclined disk galaxies - IV. New insights into the working of stellar feedback

    Science.gov (United States)

    Wang, Q. Daniel; Li, Jiangtao; Jiang, Xiaochuan; Fang, Taotao

    2016-04-01

    Galaxy evolution is regulated by the interplay between galactic discs and their surrounding medium. We study this interplay by examining how the galactic coronal emission efficiency of stellar feedback depends on the (surface and specific) star formation rates (SFRs) and other parameters for a sample of 52 Chandra-observed nearby highly inclined disc galaxies. We first measure the star-forming galactic disc sizes, as well as the SFRs of these galaxies, using data from the Wide-Field Infrared Survey Explorer, and then show that (1) the specific 0.5-2 keV luminosity of the coronal emission correlates with the specific SFR in a sub-linear fashion: on average, LX/LK∝(SFR/M*)Γ with Γ = 0.29 ± 0.12; (2) the efficiency of the emission LX/SFR decreases with increasing surface SFR (ISFR; Γ = -0.44 ± 0.12); and (3) the characteristic temperature of the X-ray-emitting plasma weakly correlates with ISFR (Γ = 0.08 ± 0.04). These results, somewhat surprising and anti-intuitive, suggest that (i) the linear correlation between LX and SFR, as commonly presented, is largely due to the correlation of these two parameters with galaxy mass; (ii) much of the mechanical energy from stellar feedback likely drives global outflows with little X-ray cooling and with a mass-loading efficiency decreasing fast with increasing ISFR (Γ ≲ -0.5); (iii) these outflows heat and inflate the medium around the galactic disks of massive galaxies, reducing its radiative cooling rate, whereas for relatively low-mass galaxies, the energy in the outflows is probably dissipated in regions far away from the galactic discs.

  16. The JCMT Nearby Galaxies Legacy Survey X. Environmental Effects on the Molecular Gas and Star Formation Properties of Spiral Galaxies

    CERN Document Server

    Mok, Angus; Golding, J; Warren, B E; Israel, F P; Serjeant, S; Knapen, J H; Sanchez-Gallego, J R; Barmby, P; Bendo, G J; Rosolowsky, E; van der Werf, P

    2015-01-01

    We present a study of the molecular gas properties in a sample of 98 HI - flux selected spiral galaxies within $\\sim25$ Mpc, using the CO $J=3-2$ line observed with the James Clerk Maxwell Telescope. We use the technique of survival analysis to incorporate galaxies with CO upper limits into our results. Comparing the group and Virgo samples, we find a larger mean H$_{2}$ mass in the Virgo galaxies, despite their lower mean HI mass. This leads to a significantly higher H$_{2}$ to HI ratio for Virgo galaxies. Combining our data with complementary H$\\alpha$ star formation rate measurements, Virgo galaxies have longer molecular gas depletion times compared to group galaxies, due to their higher H$_{2}$ masses and lower star formation rates. We suggest that the longer depletion times may be a result of heating processes in the cluster environment or differences in the turbulent pressure. From the full sample, we find that the molecular gas depletion time has a positive correlation with the stellar mass, indicative...

  17. The origin of gas in the Extended Narrow Line Region of nearby Seyfert galaxies.I. NGC 7212

    CERN Document Server

    Cracco, V; Di Mille, F; Vaona, L; Frassati, A; Smirnova, A A; La Mura, G; Moiseev, A V; Rafanelli, P

    2011-01-01

    The Extended Narrow Line Region (ENLR) of Active Galactic Nuclei (AGN) is a region of highly ionized gas with a size of few up to 15-20 kpc. When it shows a conical or bi-conical shape with the apexes pointing towards the active nucleus, this region is also called ionization cones. The ionization cones are an evidence of the Unified Model that predicts an anisotropic escape of ionizing photons from the nucleus confined to a cone by a dusty torus. Many details about the complex structure of the ENLR still remain unveiled, as for example the origin of the ionized gas. Here we present new results of a study of the physical and kinematical properties of the circumnuclear gas in the nearby Seyfert 2 galaxy NGC 7212. Medium and high resolution integral field spectra and broad-band photometric data were collected and analysed in the frame of an observational campaign of nearby Seyfert galaxies, aiming to handle the complicated issue of the origin of the gas in the ENLR. This work is based on: (i) analysis of gas phy...

  18. Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory

    CERN Document Server

    Bundy, Kevin; Law, David R; Yan, Renbin; Drory, Niv; MacDonald, Nicholas; Wake, David A; Cherinka, Brian; Sánchez-Gallego, José R; Weijmans, Anne-Marie; Thomas, Daniel; Tremonti, Christy; Masters, Karen; Coccato, Lodovico; Diamond-Stanic, Aleksandar M; Aragón-Salamanca, Alfonso; Avila-Reese, Vladimir; Badenes, Carles; Falcón-Barroso, Jésus; Belfiore, Francesco; Bizyaev, Dmitry; Blanc, Guillermo A; Bland-Hawthorn, Joss; Blanton, Michael R; Brownstein, Joel R; Byler, Nell; Cappellari, Michele; Conroy, Charlie; Dutton, Aaron A; Emsellem, Eric; Etherington, James; Frinchaboy, Peter M; Fu, Hai; Gunn, James E; Harding, Paul; Johnston, Evelyn J; Kauffmann, Guinevere; Kinemuchi, Karen; Klaene, Mark A; Knapen, Johan H; Leauthaud, Alexie; Li, Cheng; Lin, Lihwai; Maiolino, Roberto; Malanushenko, Viktor; Malanushenko, Elena; Mao, Shude; Maraston, Claudia; McDermid, Richard M; Merrifield, Michael R; Nichol, Robert C; Oravetz, Daniel; Pan, Kaike; Parejko, John K; Sanchez, Sebastian F; Schlegel, David; Simmons, Audrey; Steele, Oliver; Steinmetz, Matthias; Thanjavur, Karun; Thompson, Benjamin A; Tinker, Jeremy L; Bosch, Remco C E van den; Westfall, Kyle B; Wilkinson, David; Wright, Shelley; Xiao, Ting; Zhang, Kai

    2014-01-01

    We present an overview of a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV) that began on 2014 July 1. MaNGA will investigate the internal kinematic structure and composition of gas and stars in an unprecedented sample of 10,000 nearby galaxies. We summarize essential characteristics of the instrument and survey design in the context of MaNGA's key science goals and present prototype observations to demonstrate MaNGA's scientific potential. MaNGA employs dithered observations with 17 fiber-bundle integral field units that vary in diameter from 12" (19 fibers) to 32" (127 fibers). Two dual-channel spectrographs provide simultaneous wavelength coverage over 3600-10300 A at R~2000. With a typical integration time of 3 hr, MaNGA reaches a target r-band signal-to-noise ratio of 4-8 (per A, per 2" fiber) at 23 AB mag per sq. arcsec, which is typical for the outskirts of ...

  19. ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. II. OPTICAL IMAGING OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Rhode, Katherine L.; Salzer, John J.; Haurberg, Nathalie C.; Van Sistine, Angela; Young, Michael D. [Department of Astronomy, Indiana University, 727 East Third Street, Bloomington, IN 47405 (United States); Haynes, Martha P.; Giovanelli, Riccardo; Adams, Elizabeth A. K. [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, Saint Paul, MN 55105 (United States); Skillman, Evan D.; McQuinn, Kristen B. W., E-mail: rhode@astro.indiana.edu, E-mail: slaz@astro.indiana.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu, E-mail: betsey@astro.cornell.edu, E-mail: jcannon@macalester.edu, E-mail: skillman@astro.umn.edu, E-mail: kmcquinn@astro.umn.edu [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States)

    2013-06-15

    We present results from ground-based optical imaging of a low-mass dwarf galaxy discovered by the ALFALFA 21 cm H I survey. Broadband (BVR) data obtained with the WIYN 3.5 m telescope at Kitt Peak National Observatory (KPNO) are used to construct color-magnitude diagrams of the galaxy's stellar population down to V{sub o} {approx} 25. We also use narrowband H{alpha} imaging from the KPNO 2.1 m telescope to identify a H II region in the galaxy. We use these data to constrain the distance to the galaxy to be between 1.5 and 2.0 Mpc. This places Leo P within the Local Volume but beyond the Local Group. Its properties are extreme: it is the lowest-mass system known that contains significant amounts of gas and is currently forming stars.

  20. The ghost of a dwarf galaxy: fossils of the hierarchical formation of the nearby spiral galaxy NGC 5907

    CERN Document Server

    Martinez-Delgado, David; Gabany, R Jay; Trujillo, Ignacio; Majewski, Steven R; Pohlen, Michael

    2008-01-01

    We present with exquisite detail an extragalactic perspective of an extended stellar tidal stream wrapping around the edge-on, spiral galaxy NGC 5907. Our deep images reveal for the first time a large scale complex of arcing loops that is an excellent example of how a low-mass satellite accretion can produce an interweaved, rosette-like structure of debris dispersed in the halo of its host galaxy. The existence of this structure, which has probably formed and survived for several Gigayears, confirms that halos of spiral galaxies in the Local Universe may still contain a significant number of galactic fossils from their hierarchical formation. To examine the validity of the external accretion scenario, we present N-body simulations of the tidal disruption of a dwarf galaxy-like system in a disk galaxy plus dark halo potential that demonstrate that most of the observed tidal features observed in NGC 5907 can be explained by a single accretion event. Unfortunately, with no kinematic data and only the projected g...

  1. A Statistical Study of H I Gas in Nearby Narrow-Line AGN-Hosting Galaxies

    CERN Document Server

    Zhu, Yi-Nan

    2015-01-01

    As a quenching mechanism, AGN feedback could suppress on-going star formation in their host galaxies. On the basis of a sample of galaxies selected from ALFALFA HI survey, the dependence of their HI mass M[HI], stellar mass M[*] & HI-to-stellar mass ratio M[HI]/M[*] on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN-hostings in this sample are gas-rich galaxies, and there is no any evidence to be shown to indicate that the AGN activity could increase/decrease either M[HI] or M[HI]/M[*]. The cold neutral gas can not be fixed positions accurately just based on available HI data due to the large beam size of ALFALFA survey. In addition, even though AGN-hostings are more easily detected by HI survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN-hosting would ultimately evolve into an old red galaxy with few cold gas, then when and how the gas has been exhausted have to be solved by future hypothes...

  2. Photometric properties and luminosity function of nearby massive early-type galaxies

    CERN Document Server

    He, Y Q; Hao, C N; Jing, Y P; Mao, S; Li, Cheng

    2013-01-01

    We perform photometric analyses for a bright early-type galaxy (ETG) sample with 2949 galaxies ($M_{\\rm r}<-22.5$ mag) in the redshift range of 0.05 to 0.15, drawn from the SDSS DR7 with morphological classification from Galaxy Zoo 1. We measure the Petrosian and isophotal magnitudes, as well as the corresponding half-light radius for each galaxy. We find that our Petrosian magnitudes, and isophotal magnitudes to 25 ${\\rm mag/arcsec^2}$ and 1% of the sky brightness are on average 0.16 mag, 0.2 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. We find the overestimations are more strongly influenced by galaxy sizes than by galaxy luminosities. Similarly, the typical half-light radii ($r_{50}$) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright-end of the $r-$band luminosity...

  3. A statistical study of H i gas in nearby narrow-line AGN-hosting galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yi-Nan; Wu, Hong, E-mail: zyn@bao.ac.cn, E-mail: hwu@bao.ac.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2015-01-01

    As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (M{sub H} {sub i}), stellar mass (M{sub *}), and H i-to-stellar mass ratio (M{sub H} {sub i}/M{sub *}) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increase or decrease either M{sub H} {sub i} or M{sub H} {sub i}/M{sub *}. The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.

  4. Modelling galaxy spectra in presence of interstellar dust-III. From nearby galaxies to the distant Universe

    CERN Document Server

    Cassarà, Letizia P; Chiosi, Cesare

    2014-01-01

    Improving upon the standard evolutionary population synthesis (EPS) technique, we present spectrophotometric models of galaxies whose morphology goes from spherical structures to discs, properly accounting for the effect of dust in the interstellar medium (ISM). These models enclose three main physical components: the diffuse ISM composed by gas and dust, the complexes of molecular clouds (MCs) where active star formation occurs and the stars of any age and chemical composition. These models are based on robust evolutionary chemical models that provide the total amount of gas and stars present at any age and that are adjusted in order to match the gross properties of galaxies of different morphological type. We have employed the results for the properties of the ISM presented in Piovan, Tantalo & Chiosi (2006a) and the single stellar populations calculated by Cassar\\`a et al. (2013) to derive the spectral energy distributions (SEDs) of galaxies going from pure bulge to discs passing through a number of co...

  5. Alfalfa discovery of the nearby gas-rich dwarf galaxy Leo P. IV. Distance measurement from LBT optical imaging

    Energy Technology Data Exchange (ETDEWEB)

    McQuinn, Kristen B. W.; Skillman, Evan D.; Berg, Danielle [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Salzer, John J.; Rhode, Katherine L. [Department of Astronomy, Indiana University, 727 East 3rd Street, Bloomington, IN 47405 (United States); Adams, Elizabeth A. K.; Giovanelli, Riccardo; Haynes, Martha P. [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Dolphin, Andrew, E-mail: kmcquinn@astro.umn.edu, E-mail: skillman@astro.umn.edu, E-mail: berg@astro.umn.edu, E-mail: jcannon@macalester.edu, E-mail: rhode@astro.indiana.edu, E-mail: slaz@astro.indiana.edu, E-mail: betsey@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States)

    2013-12-01

    Leo P is a low-luminosity dwarf galaxy discovered through the blind H I Arecibo Legacy Fast ALFA survey. The H I and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with both active star formation and an underlying older population, as well as an extremely low oxygen abundance. Here, we measure the distance to Leo P by applying the tip of the red giant branch (TRGB) distance method to photometry of the resolved stellar population from new Large Binocular Telescope V and I band imaging. We measure a distance modulus of 26.19{sub −0.50}{sup +0.17} mag corresponding to a distance of 1.72{sub −0.40}{sup +0.14} Mpc. Although our photometry reaches 3 mag below the TRGB, the sparseness of the red giant branch yields higher uncertainties on the lower limit of the distance. Leo P is outside the Local Group with a distance and velocity consistent with the local Hubble flow. While located in a very low-density environment, Leo P lies within ∼0.5 Mpc of a loose association of dwarf galaxies which include NGC 3109, Antlia, Sextans A, and Sextans B, and 1.1 Mpc away from its next nearest neighbor, Leo A. Leo P is one of the lowest metallicity star-forming galaxies known in the nearby universe, comparable in metallicity to I Zw 18 and DDO 68, but with stellar characteristics similar to dwarf spheriodals (dSphs) in the Local Volume such as Carina, Sextans, and Leo II. Given its physical properties and isolation, Leo P may provide an evolutionary link between gas-rich dwarf irregular galaxies and dSphs that have fallen into a Local Group environment and been stripped of their gas.

  6. HST/ACS Direct Ages of the Dwarf Elliptical Galaxies NGC 147 and NGC 185

    Science.gov (United States)

    Geha, M.; Weisz, D.; Grocholski, A.; Dolphin, A.; van der Marel, R. P.; Guhathakurta, P.

    2015-10-01

    We present the deepest optical photometry for any dwarf elliptical (dE) galaxy based on Hubble Space Telescope Advanced Camera for Surveys (ACS) observations of the Local Group dE galaxies NGC 147 and NGC 185. Our F606W and F814W color-magnitude diagrams are the first to reach below the oldest main sequence turnoff in a dE galaxy, allowing us to determine full star formation histories in these systems. The ACS fields are located roughly ˜1.5 effective radii from the galaxy center to avoid photometric crowding. While both ACS fields show unambiguous evidence for old and intermediate age stars, the mean age of NGC 147 is ˜4-5 Gyr younger as compared to NGC 185. In NGC 147, only 40% of stars were in place 12.5 Gyr ago (z ˜ 5), with the bulk of the remaining stellar population forming between 5 to 7 Gyr. In contrast, 70% of stars were formed in NGC 185 prior to 12.5 Gyr ago with the majority of the remaining population forming between 8 to 10 Gyr ago. Star formation has ceased in both ACS fields for at least 3 Gyr. Previous observations in the central regions of NGC 185 show evidence for star formation as recent as 100 Myr ago, and a strong metallicity gradient with radius. This implies a lack of radial mixing between the center of NGC 185 and our ACS field. The lack of radial gradients in NGC 147 suggests that our inferred SFHs are more representative of its global history. We interpret the inferred differences in star formation histories to imply an earlier infall time into the M31 environment for NGC 185 as compared to NGC 147.

  7. CARMA Survey Toward Infrared-bright Nearby Galaxies (STING). III. The Dependence of Atomic and Molecular Gas Surface Densities on Galaxy Properties

    CERN Document Server

    Wong, Tony; Bolatto, Alberto D; Leroy, Adam K; Blitz, Leo; Rosolowsky, Erik; Bigiel, Frank; Fisher, David B; Ott, Jürgen; Rahman, Nurur; Vogel, Stuart N; Walter, Fabian

    2013-01-01

    We investigate the correlation between CO and HI emission in 18 nearby galaxies from the CARMA Survey Toward IR-Bright Nearby Galaxies (STING) at sub-kpc and kpc scales. Our sample, spanning a wide range in stellar mass and metallicity, reveals evidence for a metallicity dependence of the HI column density measured in regions exhibiting CO emission. Such a dependence is predicted by the equilibrium model of McKee & Krumholz, which balances H_2 formation and dissociation. The observed HI column density is often smaller than predicted by the model, an effect we attribute to unresolved clumping, although values close to the model prediction are also seen. We do not observe HI column densities much larger than predicted, as might be expected were there a diffuse HI component that did not contribute to H_2 shielding. We also find that the H_2 column density inferred from CO correlates strongly with the stellar surface density, suggesting that the local supply of molecular gas is tightly regulated by the stella...

  8. The Nature of Nearby Counterparts to Intermediate Redshift Luminous Compact Blue Galaxies II. CO Observations

    CERN Document Server

    Garland, C A; Pisano, D J; Guzmán, R; Castander, F J; Brinkmann, J

    2005-01-01

    We present the results of a single-dish beam-matched survey of the three lowest rotational transitions of CO in a sample of 20 local (D < 70 Mpc) Luminous Compact Blue Galaxies (LCBGs). These ~L*, blue, high surface brightness, starbursting galaxies were selected with the same criteria used to define LCBGs at higher redshifts. Our detection rate was 70%, with those galaxies having Lblue<7e9 Lsun no detected. We find the H2 masses of local LCBGs range from 6.6e6 to 2.7e9 Msun, assuming a Galactic CO-to-H2 conversion factor. Combining these results with our earlier HI survey of the same sample, we find that the ratio of molecular to atomic gas mass is low, typically 5-10%. Using a Large Velocity Gradient model, we find that the average gas conditions of the entire ISM in local LCBGs are similar to those found in the centers of star forming regions in our Galaxy, and nuclear regions of other galaxies. Star formation rates, determined from IRAS fluxes, are a few solar masses per year, much higher per unit d...

  9. NGC1277: a massive compact relic galaxy in the nearby Universe

    CERN Document Server

    Trujillo, Ignacio; Balcells, Marc; Vazdekis, Alexandre; Sanchez-Blazquez, Patricia

    2013-01-01

    As early as 10 Gyr ago, galaxies with more than 10^11 Msun in stars already existed. While most of these massive galaxies must have subsequently transformed through on-going star formation and mergers with other galaxies, a small fraction (10^11 Msun; Re10 Gyr) with no evidence for more recent star formation episodes. The metallicity of their stars is super-solar ([Fe/H]=0.20+-0.04) and alpha enriched ([alpha/Fe]=0.4+-0.1). This suggests a very short formation time scale for the bulk of stars of this galaxy. This object also rotates very fast (Vrot~300 km/s) and has a large velocity dispersion (sigma>300 km/s). NGC1277 will allow future explorations in full detail of properties such as the structure, internal dynamics, metallicity, dust content and initial mass function at around 10-12 Gyr back in time when the first massive galaxies were built.

  10. Surface Photometry and Radial Color Gradients of Nearby Luminous Early-type Galaxies in SDSS Stripe 82

    CERN Document Server

    Jiang, Fangzhou; Gu, Qiusheng

    2010-01-01

    We make use of the images from the Sloan Digital Sky Survey Stripe 82 to present an analysis of r band surface brightness profiles and radial color gradients (g - r, u - r) in 111 nearby early-type galaxies (ETGs). With Stripe 82 images, we are able to pay special attentions to the low-surface-brightness areas (LSB areas) of the galaxies. The LSB areas make a difference to the Sersic fittings and concentration indices, making both the indices less than the typical values for ETGs. There are about 60% negative color gradients (red-core) within 1.5Re , much more than the approximately 10% positive ones (blue-core) within the same radius. However, taking into account of the LSB areas, we find that the color gradients are not necessarily monotonic: about one third of the red-core (or blue-core) galaxies have positive (or negative) color gradients in the outer areas. So LSB areas not only make ETGs' Sersic profiles deviate from de Vaucouleur ones and shift to the disk end, but also reveal that quite a number of ET...

  11. Chandra survey of nearby highly inclined disk galaxies -- IV: New insights into the working of stellar feedback

    CERN Document Server

    Wang, Q Daniel; Jiang, Xiaochuan; Fang, Taotao

    2015-01-01

    Galaxy evolution is regulated by the interplay between galactic disks and their surrounding medium. We study this interplay by examining how the galactic coronal emission efficiency of stellar feedback depends on the (surface and specific) star formation rates (SFRs) and other parameters for a sample of 52 Chandra-observed nearby highly inclined disk galaxies. We first measure the star forming galactic disk sizes, as well as the SFRs of these galaxies, using data from the Wide-Field Infrared Survey Explorer, and then show that 1) the specific 0.5-2~keV luminosity of the coronal emission correlates with the specific SFR in a {\\sl sub-linear} fashion: on average, $L_X/L_K \\propto (SFR/M_*)^{\\Gamma}$ with $\\Gamma =0.29\\pm0.12$; 2) the efficiency of the emission $ L_X/SFR$ decreases with increasing surface SFR ($I_{SFR}$; $\\Gamma = -0.44\\pm0.12$); and 3) the characteristic temperature of the X-ray-emitting plasma weakly correlates with $I_{SFR}$ ($\\Gamma = 0.08\\pm0.04$). These results, somewhat surprising and ant...

  12. 12CO, 13CO and C18O observations along the major axes of nearby bright infrared galaxies

    CERN Document Server

    Tan, Qinghua; Zhang, Zhiyu; Xia, Xiaoyang

    2011-01-01

    We present simultaneous observations of CO,13CO and C18O J=1-0 emission in 11 nearby (cz<1000 km/s) bright infrared galaxies. Both 12CO and 13CO are detected in the centers of all galaxies, except for 13CO in NGC 3031. We have also detected C18O, CS J=2-1, and HCO+ J=1-0 emission in the nuclear regions of M82 and M51. These are the first systematical extragalactic detections of 12CO and its isotopes from the PMO 14m telescope. We have conducted half-beam spacing mapping of M82 over an area of 4'*2.5' and major axis mapping of NGC 3627, NGC 3628, NGC 4631, and M51. The radial distributions of 12CO and 13CO in NGC 3627, NGC 3628, and M51 can be well fitted by an exponential profile. The 12CO/13CO intensity ratio,R,decreases monotonically with galactocentric radius in all mapped sources. The average R in the center and disk of the galaxies are 9.9+/-3.0 and 5.6+/-1.9 respectively, much lower than the peculiar R(~24) found in the center of M82. The intensity ratios of 13CO/C18O, 13CO/HCO+ and 13CO/CS (either o...

  13. The BaLROG project - I. Quantifying the influence of bars on the kinematics of nearby galaxies

    CERN Document Server

    Seidel, M K; Martínez-Valpuesta, I; Díaz-García, S; Laurikainen, E; Salo, H; Knapen, J H

    2015-01-01

    We present the BaLROG (Bars in Low Redshift Optical Galaxies) sample of 16 morphologically distinct barred spirals to characterise observationally the influence of bars on nearby galaxies. Each galaxy is a mosaic of several pointings observed with the IFU spectrograph SAURON leading to a tenfold sharper spatial resolution (~100 pc) compared to ongoing IFU surveys. In this paper we focus on the kinematic properties. We calculate the bar strength Qb from classical torque analysis using 3.6 {\\mu}m Spitzer (S4G) images, but also develop a new method based solely on the kinematics. A correlation between the two measurements is found and backed up by N-body simulations, verifying the measurement of Qb . We find that bar strengths from ionised gas kinematics are ~2.5 larger than those measured from stellar kinematics and that stronger bars have enhanced influence on inner kinematic features. We detect that stellar angular momentum "dips" at 0.2$\\pm$0.1 bar lengths and half of our sample exhibits an anti-correlation ...

  14. Nearby supernova host galaxies from the CALIFA Survey: I. Sample, data analysis, and correlation to star-forming regions

    CERN Document Server

    Galbany, L; Mourão, A M; Rodrigues, M; Flores, H; García-Benito, R; Mast, D; Mendoza, M A; Sánchez, S F; Badenes, C; Barrera-Ballesteros, J; Bland-Hawthorn, J; Falcón-Barroso, J; García-Lorenzo, B; Gomes, J M; Delgado, R M González; Kehrig, C; Lyubenova, M; López-Sánchez, A R; de Lorenzo-Cáceres, A; Marino, R A; Meidt, S; Mollá, M; Papaderos, P; Pérez-Torres, M A; Rosales-Ortega, F F; van de Ven, G

    2014-01-01

    [Abridged] We use optical IFS of nearby SN host galaxies provided by the CALIFA Survey with the goal of finding correlations in the environmental parameters at the location of different SN types. We recover the sequence in association of different SN types to the star-forming regions by using several indicators of the ongoing and recent SF related to both the ionized gas and the stellar populations. While the total ongoing SF is on average the same for the three SN types, SNe Ibc/IIb tend to happen closer to star-forming regions and occur in higher SF density locations compared to SNe II and SNe~Ia, the latter showing the weakest correlation. SNe~Ia host galaxies have on average masses that are $\\sim$0.3-0.8~dex higher than CC SNe hosts due to a larger fraction of old stellar populations in the SNe~Ia hosts. Using the recent SN~Ia delay-time distribution and the SFHs of the galaxies, we show that the SN~Ia hosts in our sample should presently produce a factor 2 more SNe~Ia than the CC~SN hosts. Since both typ...

  15. THE JAMES CLERK MAXWELL TELESCOPE NEARBY GALAXIES LEGACY SURVEY. I. STAR-FORMING MOLECULAR GAS IN VIRGO CLUSTER SPIRAL GALAXIES

    International Nuclear Information System (INIS)

    We present large-area maps of the CO J = 3-2 emission obtained at the James Clerk Maxwell Telescope for four spiral galaxies in the Virgo Cluster. We combine these data with published CO J = 1-0, 24 μm, and Hα images to measure the CO line ratios, molecular gas masses, and instantaneous gas depletion times. For three galaxies in our sample (NGC 4254, NGC 4321, and NGC 4569), we obtain molecular gas masses of 7 x 108 - 3 x 109 M sun and disk-averaged instantaneous gas depletion times of 1.1-1.7 Gyr. We argue that the CO J = 3-2 line is a better tracer of the dense star-forming molecular gas than the CO J = 1-0 line, as it shows a better correlation with the star formation rate surface density both within and between galaxies. NGC 4254 appears to have a larger star formation efficiency (smaller gas depletion time), perhaps because it is on its first passage through the Virgo Cluster. NGC 4569 shows a large-scale gradient in the gas properties traced by the CO J = 3-2/J = 1-0 line ratio, which suggests that its interaction with the intracluster medium is affecting the dense star-forming portion of the interstellar medium directly. The fourth galaxy in our sample, NGC 4579, has weak CO J = 3-2 emission despite having bright 24 μm emission; however, much of the central luminosity in this galaxy may be due to the presence of a central active galactic nucleus.

  16. The ACS Fornax Cluster Survey. XII. Diffuse Star Clusters in Early-type Galaxies

    Science.gov (United States)

    Liu, Yiqing; Peng, Eric W.; Lim, Sungsoon; Jordán, Andrés; Blakeslee, John; Côté, Patrick; Ferrarese, Laura; Pattarakijwanich, Petchara

    2016-10-01

    Diffuse star clusters (DSCs) are old and dynamically hot stellar systems that have lower surface brightness and more extended morphology than globular clusters (GCs). Using the images from Hubble Space Telescope (HST)/ACS Fornax Cluster Survey, we find that 12 out of 43 early-type galaxies (ETGs) in the Fornax Cluster host significant numbers of DSCs. Together with literature data from the HST/ACS Virgo Cluster Survey, where 18 out of 100 ETGs were found to host DSCs, we systematically study the relationship of DSCs with GCs and their host galaxy environment. Two DSC hosts are post-merger galaxies, with most of the other hosts either having low mass or showing clear disk components. We find that while the number ratio of DSCs to GCs is nearly constant in massive galaxies, the DSC-to-GC ratio becomes systematically higher in lower-mass hosts. This suggests that DSCs may be more efficient at forming (or surviving) in low-density environments. DSC hosts are not special either in their position in the cluster or in the galactic color–magnitude diagram. Why some disk and low-mass galaxies host DSCs while others do not is still a puzzle, however. The mean ages of DSC hosts and nonhosts are similar at similar masses, implying that formation efficiency rather than survival is the reason behind different DSC number fractions in ETGs.

  17. Infall of nearby galaxies into the Virgo cluster as traced with Hubble space telescope

    Energy Technology Data Exchange (ETDEWEB)

    Karachentsev, Igor D. [Special Astrophysical Observatory RAS, Nizhnij Arkhyz, Karachai-Cherkessian Republic 369167 (Russian Federation); Tully, R. Brent; Wu, Po-Feng [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Shaya, Edward J. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Dolphin, Andrew E., E-mail: ikar@sao.ru [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States)

    2014-02-10

    We measured the tip of the red giant branch distances to nine galaxies in the direction to the Virgo cluster using the Advanced Camera for Surveys on the Hubble Space Telescope. These distances put seven galaxies (GR 34, UGC 7512, NGC 4517, IC 3583, NGC 4600, VCC 2037, and KDG 215) in front of Virgo and two galaxies (IC 3023 and KDG 177) likely inside the cluster. Distances and radial velocities of the galaxies situated between us and the Virgo core clearly exhibit the infall phenomenon toward the cluster. In the case of spherically symmetric radial infall, we estimate the radius of the 'zero-velocity surface' to be (7.2 ± 0.7) Mpc, which yields a total mass of the Virgo cluster of (8.0 ± 2.3) × 10{sup 14} M {sub ☉}, in good agreement with its virial mass estimates. We conclude that the Virgo outskirts do not contain significant amounts of dark matter beyond their virial radius.

  18. Infall of nearby galaxies into the Virgo cluster as traced with HST

    CERN Document Server

    Karachentsev, Igor D; Wu, Po-Feng; Shaya, Edward J; Dolphin, Andrew E

    2013-01-01

    We measured the Tip of the Red Giant Branch distances to nine galaxies in the direction to the Virgo cluster using the Advanced Camera for Surveys on the Hubble Space Telescope. These distances put seven galaxies: GR 34, UGC 7512, NGC 4517, IC 3583, NGC 4600, VCC 2037 and KDG 215 in front of the Virgo, and two galaxies: IC 3023, KDG 177 likely inside the cluster. Distances and radial velocities of the galaxies situated between us and the Virgo core clearly exhibit the infall phenomenon toward the cluster. In the case of spherically symmetric radial infall we estimate the radius of the "zero-velocity surface" to be (7.2+-0.7) Mpc that yields the total mass of the Virgo cluster to be (8.0+-2.3) X 10^{14} M_sun in good agreement with its virial mass estimates. We conclude that the Virgo outskirts does not contain significant amounts of dark matter beyond its virial radius.

  19. DISCOVERY OF A NEARBY SPIRAL GALAXY BEHIND THE MILKY-WAY

    NARCIS (Netherlands)

    KRAANKORTEWEG, RC; LOAN, AJ; BURTON, WB; LAHAV, O; FERGUSON, HC; HENNING, PA; LYNDENBELL, D

    1994-01-01

    THE disk of the Milky Way contains a lot of gas and dust, which obscures about 20% of the extragalactic sky. Galaxies hidden behind the Milky Way may have an important influence on the dynamics of the Local Group and its peculiar motion relative to the cosmic microwave background radiation(1,2). Her

  20. Dust Spectral Energy Distributions of Nearby Galaxies: an Insight from the Herschel Reference Survey

    CERN Document Server

    Ciesla, L; Boselli, A; Buat, V; Cortese, L; Bendo, G J; Heinis, S; Galametz, M; Eales, S; Smith, M W L; Baes, M; Bianchi, S; de Looze, I; Alighieri, S di Serego; Galliano, F; Hughes, T M; Madden, S C; Pierini, D; Rémy-Ruyer, A; Spinoglio, L; Vaccari, M; Viaene, S; Vlahakis, C

    2014-01-01

    We gather infrared (IR) photometric data from 8 to 500 microns (Spitzer, WISE, IRAS and Herschel) for all of the HRS galaxies. Draine & Li (2007) models are fit to the data from which the stellar contribution has been carefully removed. We find that our photometric coverage is sufficient to constrain all of the models parameters and that a strong constraint on the 20-60 microns range is mandatory to estimate the relative contribution of the photo-dissociation regions to the IR SED. The SED models tend to systematically under-estimate the observed 500 microns flux densities, especially for low mass systems. We provide the output parameters for all of the galaxies: the minimum intensity of the interstellar radiation field (ISRF), the fraction of PAH, the relative contribution of PDR and evolved stellar population to the dust heating, the $M_{dust}$ and the $L_{IR}$. For a subsample of gas-rich galaxies, we analyze the relations between these parameters and the integrated properties of galaxies, such as $M_*...

  1. Dark energy in six nearby galaxy flows: Synthetic phase diagrams and self-similarity

    Science.gov (United States)

    Chernin, A. D.; Teerikorpi, P.; Dolgachev, V. P.; Kanter, A. A.; Domozhilova, L. M.; Valtonen, M. J.; Byrd, G. G.

    2012-09-01

    Outward flows of galaxies are observed around groups of galaxies on spatial scales of about 1 Mpc, and around galaxy clusters on scales of 10 Mpc. Using recent data from the Hubble Space Telescope (HST), we have constructed two synthetic velocity-distance phase diagrams: one for four flows on galaxy-group scales and the other for two flows on cluster scales. It has been shown that, in both cases, the antigravity produced by the cosmic dark-energy background is stronger than the gravity produced by the matter in the outflow volume. The antigravity accelerates the flows and introduces a phase attractor that is common to all scales, corresponding to a linear velocity-distance relation (the local Hubble law). As a result, the bundle of outflow trajectories mostly follow the trajectory of the attractor. A comparison of the two diagrams reveals the universal self-similar nature of the outflows: their gross phase structure in dimensionless variables is essentially independent of their physical spatial scales, which differ by approximately a factor of 10 in the two diagrams.

  2. Star Formation in Nearby Early-Type Galaxies: The Radio Continuum Perspective

    CERN Document Server

    Nyland, Kristina; Wrobel, Joan M; Davis, Timothy A; Bureau, Martin; Alatalo, Katherine; Morganti, Raffaella; Duc, Pierre-Alain; de Zeeuw, P T; McDermid, Richard M; Crocker, Alison F; Oosterloo, Tom

    2016-01-01

    We present a 1.4 GHz Karl G. Jansky Very Large Array (VLA) study of a sample of early-type galaxies (ETGs) from the volume- and magnitude-limited ATLAS-3D survey. The radio morphologies of these ETGs at a resolution of 5" are diverse and include sources that are compact on sub-kpc scales, resolved structures similar to those seen in star-forming spiral galaxies, and kpc-scale radio jets/lobes associated with active nuclei. We compare the 1.4 GHz, molecular gas, and infrared (IR) properties of these ETGs. The most CO-rich ATLAS-3D ETGs have radio luminosities consistent with extrapolations from H_2-mass-derived star formation rates from studies of late-type galaxies. These ETGs also follow the radio-IR correlation. However, ETGs with lower molecular gas masses tend to have less radio emission relative to their CO and IR emission compared to spirals. The fraction of galaxies in our sample with high IR-radio ratios is much higher than in previous studies, and cannot be explained by a systematic underestimation o...

  3. Continuum Halos in Nearby Galaxies : An EVLA Survey (CHANG-ES). I. Introduction to the Survey

    NARCIS (Netherlands)

    Irwin, Judith; Beck, Rainer; Benjamin, R. A.; Dettmar, Ralf-Jürgen; English, Jayanne; Heald, George; Henriksen, Richard N.; Johnson, Megan; Krause, Marita; Li, Jiang-Tao; Miskolczi, Arpad; Mora, Silvia Carolina; Murphy, E. J.; Oosterloo, Tom; Porter, Troy A.; Rand, Richard J.; Saikia, D. J.; Schmidt, Philip; Strong, A. W.; Walterbos, Rene; Wang, Q. Daniel; Wiegert, Theresa

    2012-01-01

    We introduce a new survey to map the radio continuum halos of a sample of 35 edge-on spiral galaxies at 1.5 GHz and 6 GHz in all polarization products. The survey is exploiting the new wide bandwidth capabilities of the Karl G. Jansky Very Large Array (i.e., the Expanded Very Large Array) in a varie

  4. The Variation in Molecular Gas Depletion Time among Nearby Galaxies: What are the Main Parameter Dependencies?

    CERN Document Server

    Huang, Mei-Ling

    2014-01-01

    We re-analyze correlations between global molecular gas depletion time (Tdep) and galaxy parameters including stellar mass, specific star formation rate (sSFR), stellar mass surface density and concentration index. The analysis is based on the COLD GASS survey, which includes galaxies with stellar mass in the range 10^10 - 10^11.5 Msun with molecular gas mass estimates derived from CO(1-0) line measurements. We improve on previous work by Saintonge et al. (2011b) by estimating SFRs using the combination of GALEX FUV and WISE 22 micron data and by deriving Tdep within a fixed aperture set by the IRAM beam size. In our new study we find correlations with much smaller scatter. Dependences of the Tdep on galaxy structural parameters such as stellar mass surface density and concentration index are now weak or absent. Differences with previous work arise because dust extinction correlates strongly with galaxy structural parameters. We further demonstrate that the 'primary' global parameter correlation is between Td...

  5. The RINGS Survey: High-Resolution H-alpha Velocity Fields of Nearby Spiral Galaxies with the SALT Fabry-Perot

    CERN Document Server

    Mitchell, Carl J; Williams, T B; Spekkens, Kristine; Lee-Waddell, K; de Naray, Rachel Kuzio

    2015-01-01

    We have obtained high-spatial-resolution spectrophotometric data on several nearby spiral galaxies with the Southern African Large Telescope (SALT) Fabry-P\\'erot interferometer on the Robert Stobie Spectrograph (RSS) as a part of the RSS Imaging spectroscopy Nearby Galaxy Survey (RINGS). We have successfully reduced two tracks of Fabry-P\\'erot data for the galaxy NGC 2280 to produce a velocity field of the H-alpha line of excited hydrogen. We have modeled these data with the DiskFit modeling software and found these models to be in excellent agreement both with previous measurements in the literature and with our lower-resolution HI velocity field of the same galaxy. Despite this good agreement, small regions exist where the difference between the H-alpha and HI velocities is larger than would be expected from typical dispersions. We investigate these regions of high velocity difference and offer possible explanations for their existence.

  6. Surface photometry and radial color gradients of nearby luminous early-type galaxies in SDSS Stripe 82

    Institute of Scientific and Technical Information of China (English)

    Fang-Zhou Jiang; Song Huang; Qiu-Sheng Gu

    2011-01-01

    We make use of the images from the Sloan Digital Sky Survey Stripe 82 (Stripe 82) to present an analysis of r band surface brightness profiles and radial color gradients (g-r, u-r) in our sample of 111 nearby early-type galaxies (ETGs). Thanks to the Stripe 82 images, each of which is co-added from about 50 single frames, we are able to pay special attention to the low-surface-brightness areas (LSB areas) of the galaxies. The LSB areas affect the Sérsic fittings and concentration indices by making both of the indices less than the typical values for ETGs. In the Sérsic fits to all the surface brightness profiles, we found some Sérsic indices that range from 1.5 to 2.5,much smaller than those of typical de Vaucouleur profiles and relatively close to those of exponential disks, and some others much larger than four but still with accurate fitting. Two galaxies cannot be fitted with a single Sérsic profile, but once we try double Sérsic profiles, the fittings are improved: one with a profile relatively close to the de Vaucouleur law in the inner area and a profile relatively close to an exponential law in the LSB area, the other with a nice fitting in the inner area but still having a failed fitting in the outer area. About 60% of the sample has negative color gradients (red-core) within 1.5Re, much more than the approximately 10% positive ones (bluecore) within the same radius. However, taking into account the LSB areas, we find that the color gradients are not necessarily monotonic: about one third of the red-core (or blue-core) galaxies have positive (or negative) color gradients in the outer areas.So LSB areas not only make ETGs' Sérsic profiles deviate from de Vaucouleur ones and shift to the disk end, but also reveal that quite a number of ETGs have opposite color gradients in inner and outer areas. These outcomes remind us of the necessity of double-Sérsic fitting. These LSB phenomena may be interpreted by mergers and thus have different metallicity

  7. Hubble Space Telescope study of resolved red giant stars in the outer halos of nearby dwarf starburst galaxies

    CERN Document Server

    Ryś, Agnieszka; van der Marel, Roeland P; Aloisi, Alessandra; Annibali, Francesca

    2011-01-01

    [abridged] Aims. We observed the outer parts of NGC 1569 and NGC 4449, two of the closest and strongest dwarf starburst galaxies in the local universe, to characterize their stellar density and populations, and obtain new insights into the structure, formation, and evolution of starburst galaxies and galaxy halos. Methods. We obtained HST/WFPC2 images between 5 and 8 scale radii from the center, along the intermediate and minor axes. We performed point-source photometry to determine color magnitude diagrams of I vs. V-I. We compared the results at different radii, including also our prior HST/ACS results for more centrally located fields. Results. We detect stars in the RGB and TP-AGB (carbon star) phases in all outer fields, but not younger stars such as those present at smaller radii. The RGB star density profile is well fit by either a de Vaucouleurs profile or a power-law profile, but has more stars at large radii than a single exponential. To within the uncertainties, there are no radial gradients in the...

  8. First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

    Science.gov (United States)

    Miralles-Caballero, D.; Díaz, A. I.; López-Sánchez, Á. R.; Rosales-Ortega, F. F.; Monreal-Ibero, A.; Pérez-Montero, E.; Kehrig, C.; García-Benito, R.; Sánchez, S. F.; Walcher, C. J.; Galbany, L.; Iglesias-Páramo, J.; Vílchez, J. M.; González Delgado, R. M.; van de Ven, G.; Barrera-Ballesteros, J.; Lyubenova, M.; Meidt, S.; Falcon-Barroso, J.; Mast, D.; Mendoza, M. A.; Califa Collaboration

    2016-08-01

    The search of extragalactic regions with conspicuous presence of Wolf-Rayet (WR) stars outside the Local Group is challenging task owing to the difficulty in detecting their faint spectral features. In this exploratory work, we develop a methodology to perform an automated search of WR signatures through a pixel-by-pixel analysis of integral field spectroscopy (IFS) data belonging to the Calar Alto Legacy Integral Field Area survey, CALIFA. This procedure has been applied to a sample of nearby galaxies spanning a wide range of physical, morphological, and environmental properties. This technique allowed us to build the first catalogue of regions rich in WR stars with spatially resolved information, and enabled us to study the properties of these complexes in a two-dimensional (2D) context. The detection technique is based on the identification of the blue WR bump (around He iiλ4686 Å, mainly associated with nitrogen-rich WR stars; WN) and the red WR bump (around C ivλ5808 Å, mainly associated with carbon-rich WR stars; WC) using a pixel-by-pixel analysis that maximizes the number of independent regions within a given galaxy. We identified 44 WR-rich regions with blue bumps distributed in 25 out of a total of 558 galaxies. The red WR bump was identified only in 5 of those regions. Most of the WR regions are located within one effective radius from the galaxy centre, and around one-third are located within ~1 kpc or less from the centre. We found that the majority of the galaxies hosting WR populations in our sample are involved in some kind of interaction process. Half of the host galaxies share some properties with gamma-ray burst (GRB) hosts where WR stars, such as potential candidates to the progenitors of GRBs, are found. We also compared the WR properties derived from the CALIFA data with stellar population synthesis models, and confirm that simple star models are generally not able to reproduce the observations. We conclude that other effects, such as

  9. Herschel photometric observations of the nearby low metallicity irregular galaxy NGC 6822

    CERN Document Server

    Galametz, M; Galliano, F; Hony, S; Sauvage, M; Pohlen, M; Bendo, G J; Auld, R; Baes, M; Barlow, M J; Bock, J J; Boselli, A; Bradford, M; Buat, V; Castro-Rodriguez, N; Chanial, P; Charlot, S; Ciesla, L; Clements, D L; Cooray, A; Cormier, D; Cortese, L; Davies, J I; Dwek, E; Eales, S A; Elbaz, D; Gear, W K; Glenn, J; Gomez, H L; Griffin, M; Isaak, K G; Levenson, L R; Lu, N; O'Halloran, B; Okumura, K; Oliver, S; Page, M J; Panuzzo, P; Papageorgiou, A; Parkin, T J; Perez-Fournon, I; Rangwala, N; Rigby, E E; Roussel, H; Rykala, A; Sacchi, N; Schulz, B; Schirm, M R P; Smith, M W L; Spinoglio, L; Stevens, J A; Sundar, S; Symeonidis, M; Trichas, M; Vaccari, M; Vigroux, L; Wilson, C D; Wozniak, H; Wright, G S; Zeilinger, W W

    2010-01-01

    We present the first Herschel PACS and SPIRE images of the low-metallicity galaxy NGC6822 observed from 70 to 500 mu and clearly resolve the HII regions with PACS and SPIRE. We find that the ratio 250/500 is dependent on the 24 mu surface brightness in NGC6822, which would locally link the heating processes of the coldest phases of dust in the ISM to the star formation activity. We model the SEDs of some regions HII regions and less active regions across the galaxy and find that the SEDs of HII regions show warmer ranges of dust temperatures. We derive very high dust masses when graphite is used in our model to describe carbon dust. Using amorphous carbon, instead, requires less dust mass to account for submm emission due to its lower emissivity properties. This indicates that SED models including Herschel constraints may require different dust properties than commonly used.

  10. Nuclear star formation activity and black hole accretion in nearby Seyfert galaxies

    International Nuclear Information System (INIS)

    Recent theoretical and observational works indicate the presence of a correlation between the star-formation rate (SFR) and active galactic nucleus (AGN) luminosity (and, therefore, the black hole accretion rate, M-dot BH) of Seyfert galaxies. This suggests a physical connection between the gas-forming stars on kpc scales and the gas on sub-pc scales that is feeding the black hole. We compiled the largest sample of Seyfert galaxies to date with high angular resolution (∼0.''4-0.''8) mid-infrared (8-13 μm) spectroscopy. The sample includes 29 Seyfert galaxies drawn from the AGN Revised Shapley-Ames catalog. At a median distance of 33 Mpc, our data allow us to probe nuclear regions on scales of ∼65 pc (median value). We found no general evidence of suppression of the 11.3 μm polycyclic aromatic hydrocarbon (PAH) emission in the vicinity of these AGN, and we used this feature as a proxy for the SFR. We detected the 11.3 μm PAH feature in the nuclear spectra of 45% of our sample. The derived nuclear SFRs are, on average, five times lower than those measured in circumnuclear regions of 600 pc in size (median value). However, the projected nuclear SFR densities (median value of 22 M ☉ yr–1 kpc–2) are a factor of 20 higher than those measured on circumnuclear scales. This indicates that the SF activity per unit area in the central ∼65 pc region of Seyfert galaxies is much higher than at larger distances from their nuclei. We studied the connection between the nuclear SFR and M-dot BH and showed that numerical simulations reproduce our observed relation fairly well.

  11. The distribution of supermassive black holes in the nuclei of nearby galaxies

    OpenAIRE

    A. CATTANEO; Haehnelt, M. G.; Rees, M. J.

    1999-01-01

    The growth of supermassive black holes by merging and accretion in hierarchical models of galaxy formation is studied by means of Monte Carlo simulations. A tight linear relation between masses of black holes and masses of bulges arises if if the mass accreted by supermassive black holes scales linearly with the mass forming stars and if the redshift evolution of mass accretion tracks closely that of star formation. Differences in redshift evolution between black hole accretion and star forma...

  12. Identifying the chemistry of the dust around AGB stars in nearby galaxies

    CERN Document Server

    Srinivasan, Sundar; Zhao-Geisler, Ronny

    2016-01-01

    Asymptotic giant branch (AGB) stars are significant contributors to the chemical enrichment of the interstellar medium (ISM) of galaxies. It is therefore essential to constrain the AGB contribution to the dust budget in galaxies. Recent estimates of the total dust injection rate to the Large and Small Magellanic Clouds (LMC and SMC; Riebel et al. 2012, Boyer et al. 2012, Srinivasan et al. in prep) have used data from the Spitzer Space Telescope SAGE (Surveying the Agents of Galaxy Evolution; Meixner et al. 2006) and SAGE-SMC (Gordon et al. 2011) surveys. When sorted by dust chemistry, the data allow for a comparison of O-rich and carbonaceous dust-production rates. In the LMC, for instance, the rate of dust production from carbon stars is about two and a half times that from oxygen-rich AGBs. A reliable determination of the fractional contributions of the two types of dust would serve as input to models of chemical evolution. However, the Spitzer IRAC photometric bands do not sufficiently probe the characteri...

  13. Toward the Distribution of Orbital Parameters of Nearby Major Galaxy Mergers

    Science.gov (United States)

    Mortazavi Karvani, Seyed Alireza

    2016-01-01

    In this thesis project our goal is to measure the initial conditions of a sample of ~20 local disk-disk major galaxy mergers. Measuring the orbital parameters is possible by findingthe most similar galaxy merger simulation to the morphology and kinematics of the data.We have developed an automated modeling method based on the Identikit software package,which also estimates the uncertainty of the measured initial conditions. We tested our modeling method using an independent set of GADGET simulations, and we acquired reliable results onprograde merger systems. We observed the Hα kinematics of our sample using SparsePak IFU on the WIYN telescope at KPNO, and DIS on the 3.5m telescope at APO. For the few merger systems in our sample with archival HI data available, we compare the use of HI vs Hα as the kinematic tracer. This work lays the ground-work for the analysis of larger statistical samples of mergers from on-going IFU galaxy survey such as MaNGA.

  14. Bottom-heavy initial mass function in a nearby compact L*-galaxy

    CERN Document Server

    Läsker, Ronald; van de Ven, Glenn; Ferreras, Ignacio; La Barbera, Francesco; Vazdekis, Alexandre; Falcón-Barroso, Jesús

    2013-01-01

    We present orbit-based dynamical models and stellar population analysis of galaxy SDSS J151741.75-004217.6, a low-redshift (z=0.116) early-type galaxy (ETG) which, for its moderate luminosity, has an exceptionally high velocity dispersion. We aim to determine the central black hole mass (M_bh), the i-band stellar mass-to-light ratio, and the low-mass slope of the initial mass function (IMF). Combining constraints from HST imaging and longslit kinematic data with those from fitting the SDSS spectrum with stellar populations models of varying IMF, we show that this galaxy has a large fraction of low-mass stars, significantly higher than implied even by a Salpeter IMF. We exclude a Chabrier/Kroupa as well as a unimodal (i.e. single-segment) IMF, while a bimodal (low-mass tapered) shape is consistent with the dynamical constraints. Thereby, our study demonstrates that a very bottom-heavy IMF can exist even in an L* ETG. We place an upper limit of ~10^{10.5}M_sun on M_bh, which still leaves open the possibility of...

  15. Spectroscopic Study of the HST/ACS PEARS Emission-Line Galaxies

    CERN Document Server

    Xia, Lifang; Rhoads, James; Pirzkal, Norbert; Meurer, Gerhardt; Straughn, Amber; Floyd, David; Zheng, Zhenya

    2010-01-01

    We present spectroscopy of 76 emission-line galaxies (ELGs) in CDF-S taken with the LDSS3 spectrograph on Magellan Telescope. These galaxies are selected to have emission lines with ACS grism data in the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) grism Survey. While the ACS grism spectra cover the wavelength range 6000-9700 {\\AA} and most PEARS grism redshifts are based on a single emission line + photometric redshifts from broad-band colors; the Magellan spectra cover a wavelength range of 4000 {\\AA} to 9000 {\\AA}, and provide a check on redshifts derived from PEARS data. We find an accuracy of {\\sigma}z = 0.006 for the grism redshifts with only one catastrophic outlier. For 14 galaxies at z 10$^{43} ergs s$^{-1}, and power-law continuum spectra. Three objects are identified as starburst galaxies from the full-band X-ray luminosity L$_{FB} ~ 10$^{41}$ ergs s$^{-1}.

  16. The ACS Fornax Cluster Survey. XII. Diffuse Star Clusters in Early-type Galaxies

    CERN Document Server

    Liu, Yiqing; Lim, Sungsoon; Jordán, Andrés; Blakeslee, John; Côté, Patrick; Ferrarese, Laura; Pattarakijwanich, Petchara

    2016-01-01

    Diffuse star clusters (DSCs) are old and dynamically hot stellar systems that have lower surface brightness and more extended morphology than globular clusters (GCs). Using the images from HST/ACS Fornax Cluster Survey, we find that 12 out of 43 early-type galaxies (ETGs) in the Fornax cluster host significant numbers of DSCs. Together with literature data from the HST/ACS Virgo Cluster Survey, where 18 out of 100 ETGs were found to host DSCs, we systematically study the relationship of DSCs with GCs, and their host galaxy environment. Two DSC hosts are post-merger galaxies, with most of the other hosts either having low mass or showing clear disk components. We find that while the number ratio of DSCs to GCs is nearly constant in massive galaxies, the DSC-to-GC ratio becomes systematically higher in lower mass hosts. This suggests that DSCs may be more efficient at forming (or surviving) in low density environments. DSC hosts are not special either in their position in the cluster, or in the galactic color-m...

  17. Mid-infrared dust in two nearby radio galaxies, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36)

    Science.gov (United States)

    Duah Asabere, B.; Horellou, C.; Jarrett, T. H.; Winkler, H.

    2016-07-01

    Context. Most radio galaxies are hosted by giant gas-poor ellipticals, but some contain significant amounts of dust, which is likely to be of external origin. Aims: In order to characterize the mid-IR properties of two of the most nearby and brightest merger-remnant radio galaxies of the Southern hemisphere, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36), we used observations with the Wide-field Infrared Survey Explorer (WISE) at wavelengths of 3.4, 4.6, 12 and 22 μm and Spitzer mid-infrared spectra. Methods: By applying a resolution-enhancement technique, new WISE images were produced at angular resolutions ranging from 2.̋6 to 5.̋5. Global measurements were performed in the four WISE bands, and stellar masses and star-formation rates were estimated using published scaling relations. Two methods were used to uncover the distribution of dust, one relying on two-dimensional fits to the 3.4 μm images to model the starlight, and the other one using a simple scaling and subtraction of the 3.4 μm images to estimate the stellar continuum contribution to the emission in the 12 and 22 μm bands. Results: The two galaxies differ markedly in their mid-IR properties. The 3.4 μm brightness distribution can be well represented by the superposition of two Sérsic models in NGC 1316 and by a Sérsic model and an exponential disk in NGC 612. The WISE colors of NGC 1316 are typical of those of early-type galaxies; those of NGC 612 are in the range found for star-forming galaxies. From the 22 μm luminosity, we infer a star-formation rate of ~0.7 M⊙ yr-1 in NGC 1316 and ~7 M⊙ yr-1 in NGC 612. Spitzer spectroscopy shows that the 7.7-to-11.3 μm PAH line ratio is significantly lower in NGC 1316 than in NGC 612. The WISE images reveal resolved emission from dust in the central 1'-2' of the galaxies. In NGC 1316, the extra-nuclear emission coincides with two dusty regions NW and SE of the nucleus seen in extinction in optical images and where molecular gas is known to reside

  18. The Sloan Lens ACS Survey. I. A large spectroscopically selected sample of massive early-type lens galaxies

    NARCIS (Netherlands)

    Bolton, AS; Burles, S; Koopmans, LVE; Treu, T; Moustakas, LA

    2006-01-01

    The Sloan Lens ACS (SLACS) Survey is an efficient Hubble Space Telescope (HST) Snapshot imaging survey for new galaxy-scale strong gravitational lenses. The targeted lens candidates are selected spectroscopically from the Sloan Digital Sky Survey (SDSS) database of galaxy spectra for having multiple

  19. The HST/ACS Coma Cluster Survey : III. Structural parameters of galaxies using single Sersic fits star

    NARCIS (Netherlands)

    Hoyos, Carlos; den Brok, Mark; Verdoes Kleijn, Gijs; Carter, David; Balcells, Marc; Guzmán, Rafael; Peletier, Reynier; Ferguson, Henry C.; Goudfrooij, Paul; Graham, Alister W.; Hammer, Derek; Karick, Arna M.; Lucey, John R.; Matković, Ana; Merritt, David; Mouhcine, Mustapha; Valentijn, Edwin

    2011-01-01

    We present a catalogue of structural parameters for 8814 galaxies in the 25 fields of the Hubble Space Telescope/ACS Coma Treasury Survey. Parameters from Sersic fits to the two-dimensional surface brightness distributions are given for all galaxies from our published Coma photometric catalogue with

  20. Mid-infrared dust in two nearby radio galaxies, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36)

    CERN Document Server

    Asabere, B Duah; Jarrett, T; Winkler, H

    2016-01-01

    Most radio galaxies are hosted by giant gas-poor ellipticals, but some contain significant amounts of dust, which is likely to be of external origin. In order to characterize the mid-IR properties of two of the most nearby and brightest merger-remnant radio galaxies of the Southern hemisphere, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36), we used observations with the Wide-field Infrared Survey Explorer (WISE) at wavelengths of 3.4, 4.6, 12 and 22 micron and Spitzer mid-infrared spectra. By applying a resolution-enhancement technique, new WISE images were produced at angular resolutions ranging from 2.6" to 5.5". Global measurements were performed in the four WISE bands, and stellar masses and star-formation rates were estimated using published scaling relations. Two methods were used to uncover the distribution of dust, one relying on two-dimensional fits to the 3.4 micron images to model the starlight, and the other one using a simple scaling and subtraction of the 3.4 micron images to estimate the stellar...

  1. A multi-wavelength study of Supernova Remnants in six nearby galaxies. II. New optically selected Supernova Remnants

    CERN Document Server

    Leonidaki, I; Zezas, A

    2012-01-01

    We present results from a study of optically emitting Supernova Remnants (SNRs) in six nearby galaxies (NGC 2403, NGC 3077, NGC 4214, NGC 4395, NGC 4449 and NGC 5204) based on deep narrow band H{\\alpha} and [SII] images as well as spectroscopic observations. The SNR classification was based on the detected sources that fulfill the well-established emission line flux criterion of [SII]/H{\\alpha} > 0.4. This study revealed ~400 photometric SNRs down to a limiting H{\\alpha} flux of 10^(-15) erg sec^(-1) cm^(-2). Spectroscopic observations confirmed the shock-excited nature of 56 out of the 96 sources with ([SII]/H{\\alpha})$_{phot}$> 0.3 (our limit for an SNR classification) for which we obtained spectra. 11 more sources were spectroscopically identified as SNRs although their photometric [SII]/H{\\alpha} ratio was below 0.3. We discuss the properties of the optically-detected SNRs in our sample for different types of galaxies and hence different environments, in order to address their connection with the surround...

  2. Using the Ca II Triplet to Trace Abundance Variations in Individual Red Giant Branch stars in Three Nearby Galaxies

    CERN Document Server

    Tolstoy, E; Cole, A A; Pasquini, L; Gilmozzi, R; Gallagher, J S; Tolstoy, Eline; Irwin, Michael J.; Cole, Andrew A.

    2001-01-01

    Spectroscopic abundance determinations for stars spanning a Hubble time in age are necessary in order to unambiguously determine the evolutionary histories of galaxies. Using FORS1 in Multi-Object Spectroscopy mode on ANTU (UT1) at the ESO-VLT on Paranal we obtained near infrared spectra from which we measured the equivalent widths of the two strongest Ca II triplet lines to determine metal abundances for a sample of Red Giant Branch stars, selected from ESO-NTT optical (I, V-I) photometry of three nearby, Local Group, galaxies: the Sculptor Dwarf Spheroidal, the Fornax Dwarf Spheroidal and the Dwarf Irregular NGC 6822. The summed equivalent width of the two strongest lines in the Ca II triplet absorption line feature, centered at 8500A, can be readily converted into an [Fe/H] abundance using the previously established calibrations by Armandroff & Da Costa (1991) and Rutledge, Hesser & Stetson (1997). We measured metallicities for 37 stars in Sculptor, 32 stars in Fornax, and 23 stars in NGC 6822, yie...

  3. Mortality and dust expulsion in early phases of stellar clusters. Evidence from NIR photometry of nearby, spiral galaxies

    CERN Document Server

    Grosboel, P

    2013-01-01

    It is often argued that young stellar clusters suffer a significant infant mortality that is partly related to the expulsion of dust and gas in their early phases caused by radiation pressure from hot stars and supernovae. Near-infrared (J-K)-Mk diagrams of young stellar clusters in nearby spiral galaxies show a bi-modal distribution that is consistent with a fast decline of their intrinsic extinction at an early epoch. The distinct features in the color-magnitude diagrams (CMD) and the fast change of colors for the youngest clusters allow us to place constraints on their early evolutionary phases, including the time scale for the decreasing extinction caused for instance by gas and dust expulsion. Monte Carlo simulations of cluster populations were performed using the power-law distribution function g(M, t) ~ M^a t^gam. Integrated colors were computed from Starburst99 models. The simulated near-infrared CMD were compared with those observed for six grand-design, spiral galaxies using statistical goodness-of-...

  4. The JCMT Nearby Galaxies Legacy Survey. VI. The distribution of gas and star formation in M 81

    Science.gov (United States)

    Sánchez-Gallego, J. R.; Knapen, J. H.; Heiner, J. S.; Wilson, C. D.; Warren, B. E.; Allen, R. J.; Azimlu, M.; Barmby, P.; Bendo, G. J.; Comerón, S.; Israel, F. P.; Serjeant, S.; Tilanus, R. P. J.; Vlahakis, C.; van der Werf, P.

    2011-03-01

    We present the first complete 12CO J = 3-2 map of M 81, observed as part of the Nearby Galaxies Legacy Survey being carried out at the James Clerk Maxwell Telescope. We detect nine regions of significant CO emission located at different positions within the spiral arms, and confirm that the global CO emission in the galaxy is low. We combine these data with a new Hα map obtained using the Isaac Newton Telescope and archival H i, 24μm, and FUV images to uncover a correlation between the molecular gas and star forming regions in M 81. For the nine regions detected in CO J = 3-2, we combine our CO J = 3-2 data with existing CO J = 1-0 data to calculate line ratios. We find that the ratio J = (3-2)/(1-0) is in agreement with the range of typical values found in the literature (0.2-0.8). Making reasonable assumptions, this allows us to constrain the hydrogen density to the range (103-104) cm-3. We also estimated the amount of hydrogen produced in photo-dissociation regions near the locations where CO J = 3-2 was detected.

  5. The JCMT Nearby Galaxies Legacy Survey VI: The distribution of gas and star formation in M81

    CERN Document Server

    Sánchez-Gallego, J R; Heiner, J S; Wilson, C D; Warren, B E; Allen, R J; Azimlu, M; Barmby, P; Bendo, G J; Comerón, S; Israel, F P; Serjeant, S; Tilanus, R P J; Vlahakis, C; van der Werf, P

    2010-01-01

    We present a first complete 12 CO J=3-2 map of M81, observed as part of the Nearby Galaxies Legacy Survey being carried out at the James Clerk Maxwell Telescope. We detect 9 regions of significant CO emission located at different positions within the spiral arms, and confirm that the global CO emission in the galaxy is low. We combine these data with a new H-alpha map obtained using the Isaac Newton Telescope and archival HI, 24 microns and FUV images to uncover a correlation between the molecular gas and star forming regions in M81. For the nine regions detected in CO J=3-2, we combine our CO J=3-2 data with existing CO J=1-0 data to calculate line ratios. We find that the ratio J=(3-2)/(1-0) is in agreement with the range of typical values found in the literature (0.2-0.8). Making reasonable assumptions, this allows us to constrain the hydrogen density to the range (10^3-10^4) cm^{-3}. We also estimated the amount of hydrogen produced in photo-dissociation regions near the locations where CO J=3-2 was detec...

  6. Host Galaxies, Obscuration and Nuclear Structure of Three Nearby Compact Symmetric Objects

    CERN Document Server

    Perlman, E S; Conway, J; Reynolds, C; Perlman, Eric S.; Stocke, John T.; Conway, John; Reynolds, Christopher S

    2001-01-01

    We present 3-band HST imaging of three z/= 10^8 years ago. Such a merger could have "triggered" the current activity in these objects, but our data require a significant time delay between the merger and the onset of nuclear activity. However, these data are also consistent with the hypothesis that the onset of nuclear activity in radio galaxies is due to relatively minor "feeding" events and/or the formation of "bars within bars", which would disturb the internal kinematics only slightly.

  7. Stellar and Intermediate-Mass Black Holes in the Milky Way and Nearby Galaxies

    International Nuclear Information System (INIS)

    With the advent of high resolution X-ray telescopes, the ability to identify extragalactic black holes has greatly enhanced our understanding of massive compact objects, as we are no longer limited to the rather meager Milky Way black hole population. The greatly increased numbers have opened up opportunities to find new modes of compact object accretion and potentially long-sought evidence for intermediate-mass black holes. In this lecture series, the current state of knowledge of stellar- and intermediate-mass black holes is reviewed, particularly in regards to black hole populations in external galaxies.

  8. The Atlas3D project -- XXXI. Nuclear radio emission in nearby early-type galaxies

    CERN Document Server

    Nyland, Kristina; Wrobel, Joan M; Sarzi, Marc; Morganti, Raffaella; Alatalo, Katherine; Blitz, Leo; Bournaud, Frederic; Bureau, Martin; Cappellari, Michele; Crocker, Alison F; Davies, Roger L; Davis, Timothy A; de Zeeuw, P T; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnovic, Davor; Kuntschner, Harald; McDermid, Richard M; Naab, Thorsten; Oosterloo, Tom; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie

    2016-01-01

    We present the results of a high-resolution, 5 GHz, Karl G. Jansky Very Large Array study of the nuclear radio emission in a representative subset of the Atlas3D survey of early-type galaxies (ETGs). We find that 51 +/- 4% of the ETGs in our sample contain nuclear radio emission with luminosities as low as 10^18 W/Hz. Most of the nuclear radio sources have compact (< 25-110 pc) morphologies, although < 10% display multi-component core+jet or extended jet/lobe structures. Based on the radio continuum properties, as well as optical emission line diagnostics and the nuclear X-ray properties, we conclude that the majority of the central 5 GHz sources detected in the Atlas3D galaxies are associated with the presence of an active galactic nucleus (AGN). However, even at sub-arcsecond spatial resolution, the nuclear radio emission in some cases appears to arise from low-level nuclear star formation rather than an AGN, particularly when molecular gas and a young central stellar population is present. This is in...

  9. The Nuclear Structure in Nearby Luminous Infrared Galaxies: HST NICMOS Imaging of the GOALS Sample

    CERN Document Server

    Haan, S; Armus, L; Evans, A S; Howell, J H; Mazzarella, J M; Kim, D C; Vavilkin, T; Inami, H; Sanders, D B; Petric, A; Bridge, C R; Melbourne, J L; Charmandaris, V; Diaz-Santos, T; Murphy, E J; U, V; Stierwalt, S; Marshall, J A

    2010-01-01

    We present results of Hubble Space Telescope NICMOS H-band imaging of 73 of most luminous (i.e., log[L_IR/L_0]>11.4) Infrared Galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey (GOALS). This dataset combines multi-wavelength imaging and spectroscopic data from space (Spitzer, HST, GALEX, and Chandra) and ground-based telescopes. In this paper we use the high-resolution near-infrared data to recover nuclear structure that is obscured by dust at optical wavelengths and measure the evolution in this structure along the merger sequence. A large fraction of all galaxies in our sample possess double nuclei (~63%) or show evidence for triple nuclei (~6%). Half of these double nuclei are not visible in the HST B-band images due to dust obscuration. The majority of interacting LIRGs have remaining merger timescales of 0.3 to 1.3 Gyrs, based on the projected nuclear separations and the mass ratio of nuclei. We find that the bulge luminosity surface density increases significantly along the merger sequence ...

  10. CONTINUUM HALOS IN NEARBY GALAXIES: AN EVLA SURVEY (CHANG-ES). I. INTRODUCTION TO THE SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Irwin, Judith; Henriksen, Richard N. [Department of Physics, Engineering Physics and Astronomy, Queen' s University, Kingston, ON K7L 3N6 (Canada); Beck, Rainer; Krause, Marita; Mora, Silvia Carolina; Schmidt, Philip [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Benjamin, R. A. [Department of Physics, University of Wisconsin at Whitewater, 800 West Main Street, Whitewater, WI 53190 (United States); Dettmar, Ralf-Juergen; Miskolczi, Arpad [Astronomisches Institut, Ruhr-Universitaet Bochum, 44780 Bochum (Germany); English, Jayanne [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Heald, George; Oosterloo, Tom [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Johnson, Megan [National Radio Astronomy Observatory, P.O. Box 2, Greenbank, WV 24944 (United States); Li, Jiang-Tao [Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States); Murphy, E. J. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Porter, Troy A. [Hansen Experimental Physics Laboratory, Stanford University, 452 Lomita Mall, Stanford, CA 94305 (United States); Rand, Richard J. [Department of Physics and Astronomy, University of New Mexico, 800 Yale Boulevard, NE, Albuquerque, NM 87131 (United States); Saikia, D. J. [National Centre for Radio Astrophysics, TIFR, Pune University Campus, Post Bag 3, Pune 411 007 (India); Strong, A. W. [Max-Planck-Institut fuer extraterrestrische Physik, Garching bei Muenchen (Germany); Walterbos, Rene, E-mail: irwin@astro.queensu.ca, E-mail: henriksn@astro.queensu.ca, E-mail: twiegert@astro.queensu.ca, E-mail: rbeck@mpifr-bonn.mpg.de, E-mail: mkrause@mpifr-bonn.mpg.de, E-mail: cmora@mpifr-bonn.mpg.de [Department of Astronomy, New Mexico State University, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003 (United States); and others

    2012-08-15

    We introduce a new survey to map the radio continuum halos of a sample of 35 edge-on spiral galaxies at 1.5 GHz and 6 GHz in all polarization products. The survey is exploiting the new wide bandwidth capabilities of the Karl G. Jansky Very Large Array (i.e., the Expanded Very Large Array) in a variety of array configurations (B, C, and D) in order to compile the most comprehensive data set yet obtained for the study of radio halo properties. This is the first survey of radio halos to include all polarization products. In this first paper, we outline the scientific motivation of the survey, the specific science goals, and the expected improvements in noise levels and spatial coverage from the survey. Our goals include investigating the physical conditions and origin of halos, characterizing cosmic-ray transport and wind speed, measuring Faraday rotation and mapping the magnetic field, probing the in-disk and extraplanar far-infrared-radio continuum relation, and reconciling non-thermal radio emission with high-energy gamma-ray models. The sample size allows us to search for correlations between radio halos and other properties, including environment, star formation rate, and the presence of active galactic nuclei. In a companion paper (Paper II) we outline the data reduction steps and present the first results of the survey for the galaxy, NGC 4631.

  11. A nearby GRB host galaxy: VLT/X-shooter observations of HG 031203

    CERN Document Server

    Guseva, N G; Fricke, K J; Henkel, C; 10.1051/0004-6361/201116765

    2011-01-01

    (abridged) Long-duration gamma-ray bursts (LGRBs) occur in galaxies of generally low metallicity. We aim at a spectroscopic analysis of HG 031203, the host galaxy of a LRGB burst, to obtain its properties. Based on VLT/X-shooter spectroscopic observations in the wavelength range 3200-24000A, we use standard direct methods to evaluate physical conditions and element abundances. The resolving power of the instrument also allowed us to trace the kinematics of the ionised gas. We derive an interstellar oxygen abundance of 12+logO/H=8.20+/-0.03. The observed fluxes of hydrogen lines correspond to the theoretical recombination values after correction for extinction with a single value C(Hbeta)=1.67. We produce the CLOUDY photoionisation HII region model that reproduces observed emission-line fluxes of different ions in the optical range. This model also predicts emission-line fluxes in the near-infrared (NIR) and mid-infrared (MIR) ranges that agree well with the observed ones. This implies that the star-forming re...

  12. Star Formation Properties in Barred Galaxies(SFB). III. Statistical Study of Bar-driven Secular Evolution using a sample of nearby barred spirals

    CERN Document Server

    Zhou, Zhi-Min; Wu, Hong

    2014-01-01

    Stellar bars are important internal drivers of secular evolution in disk galaxies. Using a sample of nearby spiral galaxies with weak and strong bars, we explore the relationships between the star formation feature and stellar bars in galaxies. We find that galaxies with weak bars tend to be coincide with low concentrical star formation activity, while those with strong bars show a large scatter in the distribution of star formation activity. We find enhanced star formation activity in bulges towards stronger bars, although not predominantly, consistent with previous studies. Our results suggest that different stages of the secular process and many other factors may contribute to the complexity of the secular evolution. In addition, barred galaxies with intense star formation in bars tend to have active star formation in their bulges and disks, and bulges have higher star formation densities than bars and disks, indicating the evolutionary effects of bars. We then derived a possible criterion to quantify the ...

  13. The MASSIVE Survey V.: The X-ray halos of the most massive early-type galaxies in the nearby Universe

    CERN Document Server

    Goulding, Andy D; Ma, Chung-Pei; Veale, Melanie; Bogdan, Akos; Nyland, Kristina; Blakeslee, John P; McConnell, Nicholas J; Thomas, Jens

    2016-01-01

    Studies of the physical properties of local elliptical galaxies (e.g., gas temperatures, halo masses, stellar kinematics) are shedding new light on galaxy formation. Here we present the hot X-ray gas properties of 33 early-type systems within the MASSIVE galaxy survey sample that have archival Chandra X-ray observations. Through careful X-ray spectral modeling, we derive X-ray luminosities (L_X) and plasma temperatures (T_gas) for the diffuse gas components in these galaxies. We combine the MASSIVE sample with 41 galaxies from the ATLAS^3D survey to investigate the X-ray and optical properties of a statistically significant sample of nearby early-type galaxies across a wide-range of environments. We deduce that all early-type galaxies (independent of galaxy mass and rotational support) follow a universal scaling law such that L_X~T_gas^4.5. When X-ray measurements are performed consistently in apertures set by the galaxy stellar content, the wide-scale environment does not contribute to the intrinsic scatter ...

  14. Submillimetric study of nearby galaxies: A tool for new extragalactic molecules

    Science.gov (United States)

    Villicana Pedraza, Ilhuiyolitzin; Guesten, Rolf; Armijos Abendaño, Jairo; Carreto, Francisco; Martin, Sergio; Martin-Pintado, Jesus; Requena-Torres, Miguel; Perez-Beaupuits, Juan Pablo

    2016-07-01

    We present the first submillimetre line survey of extragalactic sources carried out by APEX, the results were presented inside of Villicana-Pedraza phd thesis in 2015. The surveys cover the 0.8 mm atmospheric window toward NGC253, NGC4945 and Arp220. We found HCN, C2H, CN, CS, C34S, HCO+, HNC, CO, N2H+, CH3OH are presents in all the sources, while 13CO,C18O and C17O, HNCO, H2CO, H2CS, SO, NO, SO2 were detected toward NGC253 and NGC4945, 13CN, *CO+, OCS, H2S in Arp220, 13CS, NH2CN, SiO in NGC253, and c-C3H2 in NGC4945 were detected. Column densities and rotation temperatures have been determinate using the Local Thermodinamical Equilibrium(LTE) line profile simulation and fitting in the MADCUBA IJ software. The differences found in the 32S/34S and 18O/17O ratios between the GC and the starburst galaxies NGC 4945 and NGC 253 suggest that the gas is less processed in the latter than in the GC. The high 18O/17O ratios in the galaxies NGC 4945 and NGC 253 suggest also material less processed in the nuclei of these galaxies than in the GC. This is consistent with the claim that 17O is a more representative primary product than 18O in stellar nucleosynthesis (Wilson and Rood 1994); Also, we did a Multitransitions study of H3O+ at 307GHz, 364GHz, 388GHz and 396GHz. From our non-LTE analysis of H3O+ in NGC253 with RADEX we found that the collisional excitation cannot explain the observed intensity of the ortho 396 GHz line. Excitation by radiation from the dust in the Far-IR can roughly explain the observations if the H2 densities are relatively low. From the derived H3O+ column densities we conclude that the chemistry of this molecule is dominated by ionization produce by the starburst in NGC253 (UV radiation from the O stars) and Arp 220 (cosmic rays from the supernovae) and likely from the AGN in NGC4549 (X-rays ); We report, for the first time, the tentative detection of the molecular ion HCNH+ (precursor of HCN and HNC) toward a galaxy, NGC4945, the abundance is much

  15. Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way

    International Nuclear Information System (INIS)

    In this paper the fundamental properties of the brightest known stars in our Galaxy are determined for future comparison with results for the most luminous stars in other galaxies. The H-R diagrams (M/sub v/ versus spectral type and M/sub bol/ versus log T/sub e/), the luminosities of the brightest stars, and the ratios of blue to red supergiants are all discussed, and a catalog of over 1000 supergiants and O stars in associations and clusters is included at the end of the paper.The ''theoretical'' H-R diagram (M/sub bol/ versus log T/sub e/) reveals a group of superluminous O stars with M/sub bol/ between -12 mag, a lack of evolved supergiants at these very high luminosities, and an apparent upper limit to the luminosities of the later-type supergiants (>B5) near M/sub bol/=-9.5 mag.The most luminous red supergiants have a maximum visual luminosity near M/sub v/approx. =-8 mag, supporting the suggestion by Sandage and Tammann that they are good distance indicators. Excluding the superluminous star Cyg OB 2 No. 12 (M/sub v/approx. =-9.9 mag), the brightest blue stars are found at M/sub v/approx. =-8.5 mag.The variation of the ratio of blue to red supergiants with luminosity is discussed. There is also evidence for a gradient in this ratio with distance from the galactic center, although the results are limited by the incompleteness of the data

  16. CONTINUUM HALOS IN NEARBY GALAXIES: AN EVLA SURVEY (CHANG-ES). II. FIRST RESULTS ON NGC 4631

    Energy Technology Data Exchange (ETDEWEB)

    Irwin, Judith; Henriksen, Richard N. [Department of Physics, Engineering Physics and Astronomy, Queen' s University, Kingston, ON K7L 3N6 (Canada); Beck, Rainer; Krause, Marita; Mora, Silvia Carolina; Schmidt, Philip [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121, Bonn (Germany); Benjamin, R. A. [Department of Physics, University of Wisconsin at Whitewater, 800 West Main St., Whitewater, WI 53190 (United States); Dettmar, Ralf-Juergen; Miskolczi, Arpad [Astronomisches Institut, Ruhr-Universitaet Bochum, 44780 Bochum (Germany); English, Jayanne [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Heald, George; Oosterloo, Tom [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA, Dwingeloo (Netherlands); Johnson, Megan [National Radio Astronomy Observatory, P.O. Box 2, Greenbank, WV 24944 (United States); Li, Jiang-Tao [Department of Astronomy, University of Massachusetts, 710 North Pleasant St., Amherst, MA 01003 (United States); Murphy, E. J. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Porter, Troy A. [Hansen Experimental Physics Laboratory, Stanford University, 452 Lomita Mall, Stanford, CA 94305 (United States); Rand, Richard J. [Department of Physics and Astronomy, University of New Mexico, 800 Yale Boulevard, NE, Albuquerque, NM 87131 (United States); Saikia, D. J. [National Centre for Radio Astrophysics, TIFR, Pune University Campus, Post Bag 3, Pune 411 007 (India); Strong, A. W. [Max-Planck-Institut fuer extraterrestrische Physik, Garching bei Muenchen (Germany); Walterbos, Rene, E-mail: irwin@astro.queensu.ca, E-mail: henriksn@astro.queensu.ca, E-mail: twiegert@astro.queensu.ca, E-mail: rbeck@mpifr-bonn.mpg.de, E-mail: mkrause@mpifr-bonn.mpg.de, E-mail: cmora@mpifr-bonn.mpg.de [Department of Astronomy, New Mexico State University, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003 (United States); and others

    2012-08-15

    We present the first results from the Continuum Halos in Nearby Galaxies-an EVLA Survey (CHANG-ES), a new survey of 35 edge-on galaxies to search for both in-disk and extraplanar radio continuum emission. CHANG-ES is exploiting the new wide-band, multi-channel capabilities of the Karl G. Jansky Very Large Array (i.e., the Expanded Very Large Array or EVLA) with observations in two bands centered at 1.5 and 6 GHz in a variety of array configurations with full polarization. The motivation and science case for the survey are presented in a companion paper (Paper I). These first results are based on C-array test observations in both observing bands of the well-known radio halo galaxy, NGC 4631. In this paper, we outline the observations and the data reduction steps that are required for wide-band calibration and mapping of EVLA data, including polarization. With modest on-source observing times (30 minutes at 1.5 GHz and 75 minutes at 6 GHz for the test data), we have achieved best rms noise levels of 22 and 3.5 {mu}Jy beam{sup -1} at 1.5 GHz and 6 GHz, respectively. New disk-halo features have been detected, among them two at 1.5 GHz that appear as loops in projection. We present the first 1.5 GHz spectral index map of NGC 4631 to be formed from a single wide-band observation in a single array configuration. This map represents tangent slopes to the intensities within the band centered at 1.5 GHz, rather than fits across widely separated frequencies as has been done in the past and is also the highest spatial resolution spectral index map yet presented for this galaxy. The average spectral index in the disk is {alpha}-bar{sub 1.5GHz} = -0.84 {+-} 0.05 indicating that the emission is largely non-thermal, but a small global thermal contribution is sufficient to explain a positive curvature term in the spectral index over the band. Two specific star-forming regions have spectral indices that are consistent with thermal emission. Polarization results (uncorrected for

  17. The Nature of Nearby Counterparts to Intermediate Redshift Luminous Compact Blue Galaxies I. Optical/H I Properties and Dynamical Masses

    CERN Document Server

    Garland, C A; Williams, J P; Guzmán, R; Castander, F J

    2004-01-01

    We present single-dish H I spectra obtained with the Green Bank Telescope, along with optical photometric properties from the Sloan Digital Sky Survey, of 20 nearby (D < 70 Mpc) Luminous Compact Blue Galaxies (LCBGs). These ~L*, blue, high surface brightness, starbursting galaxies were selected with the same criteria used to define LCBGs at higher redshifts. We find these galaxies are gas-rich, with M(HI) ranging from 5*10^8 to 8*10^9 M_sun, and M(HI)/L_B ranging from 0.2 to 2 M_sun/L_sun, consistent with a variety of morphological types of galaxies. We find the dynamical masses (measured within R_25) span a wide range, from 3*10^9 to 1*10^11 M_sun. However, at least half have dynamical mass-to-light ratios smaller than nearby galaxies of all Hubble types, as found for LCBGs at intermediate redshifts. By comparing line widths and effective radii with local galaxy populations, we find that LCBGs are consistent with the dynamical mass properties of Magellanic (low luminosity) spirals, and the more massive ir...

  18. The JCMT Nearby Galaxies Legacy Survey VIII. CO data and the L(CO3-2)-L(FIR) correlation in the SINGS sample

    CERN Document Server

    Wilson, C D; Israel, F P; Serjeant, S; Attewell, D; Bendo, G J; Butner, H M; Chanial, P; Clements, D L; Golding, J; Heesen, V; Irwin, J; Leech, J; Matthews, H E; Muhle, S; Mortier, A M J; Petitpas, G; Sanchez-Gallego, J R; Sinukoff, E; Shorten, K; Tan, B K; Tilanus, R P J; Usero, A; Vaccari, M; Wiegert, T; Zhu, M; Alexander, D M; Alexander, P; Azimlu, M; Barmby, P; Borys, C; Brar, R; Bridge, C; Brinks, E; Brooks, S; Coppin, K; Cote, S; Cote, P; Courteau, S; Davies, J; Eales, S; Fich, M; Hudson, M; Hughes, D H; Ivison, R J; Knapen, J H; Page, M; Parkin, T J; Pope, A; Rigopoulou, D; Rosolowsky, E; Seaquist, E R; Spekkens, K; Tanvir, N; van der Hulst, J M; van der Werf, P; Vlahakis, C; Webb, T M; Weferling, B; White, G J

    2012-01-01

    The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey (NGLS) comprises an HI-selected sample of 155 galaxies spanning all morphological types with distances less than 25 Mpc. We describe the scientific goals of the survey, the sample selection, and the observing strategy. We also present an atlas and analysis of the CO J=3-2 maps for the 47 galaxies in the NGLS which are also part of the Spitzer Infrared Nearby Galaxies Survey. We find a wide range of molecular gas mass fractions in the galaxies in this sample and explore the correlation of the far-infrared luminosity, which traces star formation, with the CO luminosity, which traces the molecular gas mass. By comparing the NGLS data with merging galaxies at low and high redshift which have also been observed in the CO J=3-2 line, we show that the correlation of far-infrared and CO luminosity shows a significant trend with luminosity. This trend is consistent with a molecular gas depletion time which is more than an order of magnitude faster in the ...

  19. THE HST/ACS COMA CLUSTER SURVEY. IV. INTERGALACTIC GLOBULAR CLUSTERS AND THE MASSIVE GLOBULAR CLUSTER SYSTEM AT THE CORE OF THE COMA GALAXY CLUSTER

    International Nuclear Information System (INIS)

    Intracluster stellar populations are a natural result of tidal interactions in galaxy clusters. Measuring these populations is difficult, but important for understanding the assembly of the most massive galaxies. The Coma cluster of galaxies is one of the nearest truly massive galaxy clusters and is host to a correspondingly large system of globular clusters (GCs). We use imaging from the HST/ACS Coma Cluster Survey to present the first definitive detection of a large population of intracluster GCs (IGCs) that fills the Coma cluster core and is not associated with individual galaxies. The GC surface density profile around the central massive elliptical galaxy, NGC 4874, is dominated at large radii by a population of IGCs that extend to the limit of our data (R +4000-5000 (systematic) IGCs out to this radius, and that they make up ∼70% of the central GC system, making this the largest GC system in the nearby universe. Even including the GC systems of other cluster galaxies, the IGCs still make up ∼30%-45% of the GCs in the cluster core. Observational limits from previous studies of the intracluster light (ICL) suggest that the IGC population has a high specific frequency. If the IGC population has a specific frequency similar to high-SN dwarf galaxies, then the ICL has a mean surface brightness of μV ∼ 27 mag arcsec-2 and a total stellar mass of roughly 1012 Msun within the cluster core. The ICL makes up approximately half of the stellar luminosity and one-third of the stellar mass of the central (NGC 4874+ICL) system. The color distribution of the IGC population is bimodal, with blue, metal-poor GCs outnumbering red, metal-rich GCs by a ratio of 4:1. The inner GCs associated with NGC 4874 also have a bimodal distribution in color, but with a redder metal-poor population. The fraction of red IGCs (20%), and the red color of those GCs, implies that IGCs can originate from the halos of relatively massive, L* galaxies, and not solely from the disruption of dwarf

  20. Three-micron spectra of AGB stars and supergiants in nearby galaxies

    CERN Document Server

    Matsuura, M; Van Loon, J T; Yamamura, I; Markwick, A J; Whitelock, P A; Woods, P M; Marshall, J R; Feast, M W; Waters, L B F M

    2005-01-01

    The dependence of stellar molecular bands on the metallicity is studied using infrared L-band spectra of AGB stars (both carbon-rich and oxygen-rich) and M-type supergiants in the Large and Small Magellanic Clouds (LMC and SMC) and in the Sagittarius Dwarf Spheroidal Galaxy. The spectra cover SiO bands for oxygen-rich stars, and acetylene (C2H2), CH and HCN bands for carbon-rich AGB stars. The equivalent width of acetylene is found to be high even at low metallicity. The high C2H2 abundance can be explained with a high carbon-to-oxygen (C/O) ratio for lower metallicity carbon stars. In contrast, the HCN equivalent width is low: fewer than half of the extra-galactic carbon stars show the 3.5micron HCN band, and only a few LMC stars show high HCN equivalent width. HCN abundances are limited by both nitrogen and carbon elemental abundances. The amount of synthesized nitrogen depends on the initial mass, and stars with high luminosity (i.e. high initial mass) could have a high HCN abundance. CH bands are found in...

  1. A Tidal Disruption Event in a Nearby Galaxy Hosting an Intermediate Mass Black Hole

    Science.gov (United States)

    Donato, D; Cenko, S. B.; Covino, S.; Troja, E.; Pursimo, T.; Cheung, C. C.; Fox, O.; Kutyrev, A.; Campana, S.; Fugazza, D.; Landt, H.; Butler, N. R.

    2014-01-01

    We report the serendipitous discovery of a bright point source flare in the Abell cluster A1795 with archival EUVE and Chandra observations. Assuming the EUVE emission is associated with the Chandra source, the X-ray 0.5-7 kiloelectronvolt flux declined by a factor of approximately 2300 over a time span of 6 years, following a power-law decay with index approximately equal to 2.44 plus or minus 0.40. The Chandra data alone vary by a factor of approximately 20. The spectrum is well fit by a blackbody with a constant temperature of kiloteslas approximately equal to 0.09 kiloelectronvolts (approximately equal to 10 (sup 6) Kelvin). The flare is spatially coincident with the nuclear region of a faint, inactive galaxy with a photometric redshift consistent at the 1 sigma level with the cluster (redshift = 0.062476).We argue that these properties are indicative of a tidal disruption of a star by a black hole (BH) with log(M (sub BH) / M (sub 1 solar mass)) approximately equal to 5.5 plus or minus 0.5. If so, such a discovery indicates that tidal disruption flares may be used to probe BHs in the intermediate mass range, which are very difficult to study by other means.

  2. The nuclear X-ray emission of nearby early-type galaxies

    CERN Document Server

    Pellegrini, S

    2010-01-01

    Nuclear hard X-ray luminosities (Lx,nuc) for a sample of 112 early type galaxies within a distance of 67 Mpc are used to investigate their relationship with the central galactic black hole mass Mbh, the inner galactic structure (using the parameters describing its cuspiness), the age of the stellar population in the central galactic region, the hot gas content and the core radio luminosity. Lx,nuc ranges from 10^{38} to 10^{42} erg/s, and the Eddington ratio Lx,nuc/Ledd from 10^{-9} to 10^{-4}. Lx,nuc increases on average with the galactic luminosity Lb and Mbh, with a wide variation by up to 4 orders of magnitude at any fixed Lb>6x10^9 Lb,sun or Mbh>10^7 Msun. This large range should reflect a large variation of the mass accretion rate \\dotMbh. On the circumnuclear scale, \\dotMbh at fixed Lb (or Mbh) could vary due to differences in the fuel production rate from the stellar mass return linked to the inner galactic structure; however, \\dotMbh should vary with cuspiness by a factor exceeding a few only in hot ...

  3. The VIRUS-P Exploration of Nearby Galaxies (VENGA): The Xco Gradient in NGC 628

    CERN Document Server

    Blanc, Guillermo A; Evans, Neal J; Jogee, Shardha; Bolatto, Alberto; Leroy, Adam K; Song, Mimi; Bosch, Remco C E van den; Drory, Niv; Fabricius, Maximilian; Fisher, David; Gebhardt, Karl; Heiderman, Amanda; Marinova, Irina; Vogel, Stuart; Weinzirl, Tim

    2012-01-01

    We measure the radial profile of the 12CO(1-0) to H_2 conversion factor (Xco) in NGC 628. The H\\alpha emission from the VENGA integral field spectroscopy is used to map the star formation rate surface density (\\Sigma_{SFR}). We estimate the molecular gas surface density (\\Sigma_{H2}) from \\Sigma_{SFR} by inverting the molecular star formation law (SFL), and compare it to the CO intensity to measure Xco. We study the impact of systematic uncertainties by changing the slope of the SFL, using different SFR tracers (H\\alpha vs. far-UV plus 24\\mu m), and CO maps from different telescopes (single-dish and interferometers). The observed Xco profile is robust against these systematics, drops by a factor of 2 from R~7 kpc to the center of the galaxy, and is well fit by a gradient \\Delta log(Xco)=0.06\\pm0.02 dex kpc^-1. We study how changes in Xco follow changes in metallicity, gas density, and ionization parameter. Theoretical models show that the gradient in Xco can be explained by a combination of decreasing metalli...

  4. A tidal disruption event in a nearby galaxy hosting an intermediate mass black hole

    International Nuclear Information System (INIS)

    We report the serendipitous discovery of a bright point source flare in the Abell cluster A1795 with archival EUVE and Chandra observations. Assuming the EUVE emission is associated with the Chandra source, the X-ray 0.5-7 keV flux declined by a factor of ∼2300 over a time span of 6 yr, following a power-law decay with index ∼2.44 ± 0.40. The Chandra data alone vary by a factor of ∼20. The spectrum is well fit by a blackbody with a constant temperature of kT ∼ 0.09 keV (∼106 K). The flare is spatially coincident with the nuclear region of a faint, inactive galaxy with a photometric redshift consistent at the 1σ level with the cluster (z = 0.062476). We argue that these properties are indicative of a tidal disruption of a star by a black hole (BH) with log (M BH/M ☉) ∼ 5.5 ± 0.5. If so, such a discovery indicates that tidal disruption flares may be used to probe BHs in the intermediate mass range, which are very difficult to study by other means.

  5. The structure and dynamics of the AC114 galaxy cluster revisited

    CERN Document Server

    Proust, Dominique; Saviane, Ivo; Ivanov, Valentin D; Bresolin, Fabio; Salzer, John J; Capelato, Hugo V

    2015-01-01

    We present a dynamical analysis of the galaxy cluster AC114 based on a catalogue of 524 velocities. Of these, 169 (32%) are newly obtained at ESO (Chile) with the VLT and the VIMOS spectrograph. Data on individual galaxies are presented and the accuracy of the measured velocities is discussed. Dynamical properties of the cluster are derived. We obtain an improved mean redshift value z= 0.31665 +/- 0.0008 and velocity dispersion \\sigma= 1893+73-82 \\kms. A large velocity dispersion within the core radius and the shape of the infall pattern suggests that this part of the cluster is in a radial phase of relaxation with a very elongated radial filament spanning 12000 \\kms. A radial foreground structure is detected within the central 0.5/h Mpc radius, recognizable as a redshift group at the same central redshift value. We analyze the color distribution for this archetype Butcher-Oemler galaxy cluster and identify the separate red and blue galaxy sequences. The latter subset contains 44% of confirmed members of the ...

  6. Optical observations of the nearby galaxy IC342 with narrow band [SII] and H$\\alpha$ filters. II - Detection of 16 Optically-Identified Supernova Remnant Candidates

    CERN Document Server

    Vucetic, M M; Pavlovic, M Z; Pannuti, T G; Petrov, N; Goker, U D; Ercan, E N

    2015-01-01

    We present the detection of 16 optical supernova remnant (SNR) candidates in the nearby spiral galaxy IC342. The candidates were detected by applying [SII]/H$\\alpha$ ratio criterion on observations made with the 2 m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper, we report the coordinates, diameters, H$\\alpha$ and [SII] fluxes for 16 SNRs detected in two fields of view in the IC342 galaxy. Also, we estimate that the contamination of total H$\\alpha$ flux from SNRs in the observed portion of IC342 is 1.4%. This would represent the fractional error when the star formation rate (SFR) for this galaxy is derived from the total galaxy's H$\\alpha$ emission.

  7. SPIRITS 15c and SPIRITS 14buu: Two Obscured Supernovae in the Nearby Star-Forming Galaxy IC 2163

    CERN Document Server

    Jencson, Jacob E; Johansson, Joel; Contreras, Carlos; Castellón, Sergio; Bond, Howard E; Monson, Andrew J; Masci, Frank J; Cody, Ann Marie; Andrews, Jennifer E; Bally, John; Cao, Yi; Fox, Ori D; Gburek, Timothy; Gehrz, Robert D; Green, Wayne; Helou, George; Hsiao, Eric; Morrell, Nidia; Phillips, Mark; Prince, Thomas A; Simcoe, Robert A; Smith, Nathan; Tinyanont, Samaporn; Williams, Robert

    2016-01-01

    SPIRITS---SPitzer InfraRed Intensive Transients Survey---is an ongoing survey of nearby galaxies searching for infrared (IR) transients with Spitzer/IRAC. We present the discovery and follow-up observations of one of our most luminous ($M_{[4.5]} = -17.1\\pm0.4$ mag, Vega) and red ($[3.6] - [4.5] = 3.0 \\pm 0.2$ mag) transients, SPIRITS 15c. The transient was detected in a dusty spiral arm of IC 2163 ($D\\approx35.5$ Mpc). Pre-discovery ground-based imaging revealed an associated, shorter-duration transient in the optical and near-IR (NIR). NIR spectroscopy showed a broad ($\\approx 8400$ km s$^{-1}$), double-peaked emission line of He I at $1.083 \\mu$m, indicating an explosive origin. The NIR spectrum of SPIRITS 15c is similar to that of the Type IIb SN 2011dh at a phase of $\\approx 200$ days. Assuming $A_V = 2.2$ mag of extinction in SPIRITS 15c provides a good match between their optical light curves. The IR light curves and the extreme $[3.6]-[4.5]$ color cannot be explained using only a standard extinction l...

  8. Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction

    CERN Document Server

    Pratt, G W; Piffaretti, R; Böhringer, H; Ponman, T J; Croston, J H; Voit, G M; Borgani, S; Bower, R G

    2009-01-01

    (Abridged) We examine the radial entropy distribution and its scaling using 31 nearby galaxy clusters from the Representative XMM-Newton Cluster Structure Survey (REXCESS). The entropy profiles are robustly measured at least out to R_1000 in all systems and out to R_500 in 13 systems. Compared to theoretical expectations, the observed distributions show a radial and mass-dependent excess entropy that is greater and extends to larger radii in lower mass systems. At R_500, the mass dependence and entropy excess are both negligible within the uncertainties. Mirroring this behaviour, the scaling of gas entropy is shallower than self-similar in the inner regions, but steepens with radius, becoming consistent with self-similar at R_500. The dispersion in scaled entropy in the inner regions is linked to the presence of cool cores and dynamical activity; at larger radii the dispersion decreases by a factor of two and the dichotomy between subsamples disappears. Parameterising the profiles with a power law plus consta...

  9. Lack of Interaction between the Dust Grains and the Anomalous Radio Jet in the Nearby Spiral Galaxy NGC 4258

    CERN Document Server

    Laine, Seppo; Tabatabaei, Fatemeh S; Siopis, Christos

    2010-01-01

    We obtained Spitzer/IRAC 3.6-8 micron images of the nearby spiral galaxy NGC 4258 to study possible interactions between dust and the radio jet. In our analysis we also included high-resolution radio continuum, H-alpha, CO, and X-ray data. Our data reveal that the 8 micron emission, believed to originate largely from PAH molecules and hot dust, is an excellent tracer of the normal spiral structure in NGC 4258, and hence it originates from the galactic plane. We investigated the possibility of dust destruction by the radio jet by calculating correlation coefficients between the 8 micron and radio continuum emissions along the jet in two independent ways, namely (i) from wavelet-transformed maps of the original images at different spatial scales, and (ii) from one-dimensional intensity cuts perpendicular to the projected path of the radio jet on the sky. No definitive sign of a correlation (or anticorrelation) was detected on relevant spatial scales with either approach, implying that any dust destruction must ...

  10. The inner $\\sim$ 40 pc Radial Distribution of the Star formation Rate for a nearby Seyfert 2 galaxy M51

    CERN Document Server

    Fang, Li-Ling; He, Zhi-Cheng; Bian, Wei-Hao

    2015-01-01

    We investigate spatially resolved specific star formation rate (SSFR) in the inner $\\sim$ 40 pc for a nearby Seyfert 2 galaxy, M51 (NGC 5194) by analyzing spectra obtained with the \\emph{Hubble Space Telescope (HST)} Space Telescope Imaging Spectrograph (STIS). We present 24 radial spectra measured along the STIS long slit in M51, extending $\\sim 1\\arcsec$ from the nucleus (i.e., -41.5 pc to 39.4 pc). By the simple stellar population synthesis, the stellar contributions in these radial optical spectra are modeled. Excluding some regions with zero young flux fraction near the center (from -6 pc to 2 pc), we find that the mean flux fraction of young stellar populations (younger than 24.5 Myr) is about 9 \\%, the mean mass fraction is about 0.09\\%. The young stellar populations are not required in the center inner $\\sim$ 8 pc in M51, suggesting a possible SSFR suppression in the circumnuclear region ($\\sim$ 10 pc) from the feedback of active galactic nuclei (AGNs). The radial distribution of SSFR in M51 is not sy...

  11. The CO-to-H2 Conversion Factor and Dust-to-Gas Ratio on Kiloparsec Scales in Nearby Galaxies

    CERN Document Server

    Sandstrom, K M; Walter, F; Bolatto, A D; Croxall, K V; Draine, B T; Wilson, C D; Wolfire, M; Calzetti, D; Kennicutt, R C; Aniano, G; Meyer, J Donovan; Usero, A; Bigiel, F; Brinks, E; de Blok, W J G; Crocker, A; Dale, D; Engelbracht, C W; Galametz, M; Groves, B; Hunt, L K; Koda, J; Kreckel, K; Linz, H; Meidt, S; Pellegrini, E; Rix, H -W; Roussel, H; Schinnerer, E; Schruba, A; Schuster, K -F; Skibba, R; van der Laan, T; Appleton, P; Armus, L; Brandl, B; Gordon, K; Hinz, J; Krause, O; Montiel, E; Sauvage, M; Schmiedeke, A; Smith, J D T; Vigroux, L

    2012-01-01

    We present maps of the CO-to-H2 conversion factor (alpha_co) and dust-to-gas ratio (DGR) in 26 nearby, star-forming galaxies with ~kiloparsec spatial resolution. We have simultaneously solved for alpha_co and DGR by assuming that the DGR is approximately constant on kpc scales. With this assumption, we can combine maps of dust mass surface density, CO integrated intensity and HI column density to solve for both alpha_co and DGR with no assumptions about their value or dependence on metallicity or other parameters. Such a study has just become possible with the availability of high resolution far-IR maps from the Herschel key program KINGFISH, 12CO J=(2-1) maps from the IRAM 30m large program HERACLES and HI 21-cm line maps from THINGS. We use a fixed ratio between the (2-1) and (1-0) lines to present our alpha_co results on the more typically used 12CO J=(1-0) scale and show using literature measurements that variations in the line ratio do not effect our results. In total, we derive 782 individual solutions ...

  12. A 15.65-solar-mass black hole in an eclipsing binary in the nearby spiral galaxy M 33.

    Science.gov (United States)

    Orosz, Jerome A; McClintock, Jeffrey E; Narayan, Ramesh; Bailyn, Charles D; Hartman, Joel D; Macri, Lucas; Liu, Jiefeng; Pietsch, Wolfgang; Remillard, Ronald A; Shporer, Avi; Mazeh, Tsevi

    2007-10-18

    Stellar-mass black holes are found in X-ray-emitting binary systems, where their mass can be determined from the dynamics of their companion stars. Models of stellar evolution have difficulty producing black holes in close binaries with masses more than ten times that of the Sun (>10; ref. 4), which is consistent with the fact that the most massive stellar black holes known so far all have masses within one standard deviation of 10. Here we report a mass of (15.65 +/- 1.45) for the black hole in the recently discovered system M 33 X-7, which is located in the nearby galaxy Messier 33 (M 33) and is the only known black hole that is in an eclipsing binary. To produce such a massive black hole, the progenitor star must have retained much of its outer envelope until after helium fusion in the core was completed. On the other hand, in order for the black hole to be in its present 3.45-day orbit about its (70.0 +/- 6.9) companion, there must have been a 'common envelope' phase of evolution in which a significant amount of mass was lost from the system. We find that the common envelope phase could not have occurred in M 33 X-7 unless the amount of mass lost from the progenitor during its evolution was an order of magnitude less than what is usually assumed in evolutionary models of massive stars.

  13. MID-INFRARED PROPERTIES OF NEARBY LUMINOUS INFRARED GALAXIES. I. SPITZER INFRARED SPECTROGRAPH SPECTRA FOR THE GOALS SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Stierwalt, S.; Armus, L.; Surace, J. A.; Inami, H.; Petric, A. O.; Diaz-Santos, T.; Haan, S.; Howell, J.; Marshall, J. [Spitzer Science Center, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Charmandaris, V. [Department of Physics and ITCP, University of Crete, GR-71003 Heraklion (Greece); Kim, D. C. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Mazzarella, J. M.; Chan, B. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Spoon, H. W. W. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Veilleux, S. [Astronomy Department, University of Maryland, College Park, MD 20742 (United States); Evans, A. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Sanders, D. B. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96825 (United States); Appleton, P. [NASA Herschel Science Center, 770 S. Wilson Ave., Pasadena, CA 91125 (United States); Bothun, G. [Physics Department, University of Oregon, Eugene, OR 97402 (United States); Bridge, C. R., E-mail: sabrinas@virginia.edu [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); and others

    2013-05-01

    The Great Observatories All-Sky LIRG Survey (GOALS) is a comprehensive, multiwavelength study of luminous infrared galaxies (LIRGs) in the local universe. Here we present low resolution Spitzer Infrared Spectrograph spectra covering 5-38 {mu}m and provide a basic analysis of the mid-IR spectral properties observed for nearby LIRGs. In a companion paper, we discuss detailed fits to the spectra and compare the LIRGs to other classes of galaxies. The GOALS sample of 244 nuclei in 180 luminous (10{sup 11} {<=} L {sub IR}/L {sub Sun} < 10{sup 12}) and 22 ultraluminous (L {sub IR}/L {sub Sun} {>=} 10{sup 12}) IR galaxies represents a complete subset of the IRAS Revised Bright Galaxy Sample and covers a range of merger stages, morphologies, and spectral types. The majority (>60%) of the GOALS LIRGs have high 6.2 {mu}m polycyclic aromatic hydrocarbon (PAH) equivalent widths (EQW{sub 6.2{mu}m} > 0.4 {mu}m) and low levels of silicate absorption (s {sub 9.7{mu}m} > -1.0). There is a general trend among the U/LIRGs for both silicate depth and mid-infrared (MIR) slope to increase with increasing L {sub IR}. U/LIRGs in the late to final stages of a merger also have, on average, steeper MIR slopes and higher levels of dust obscuration. Together, these trends suggest that as gas and dust is funneled toward the center of a coalescing merger, the nuclei become more compact and more obscured. As a result, the dust temperature increases also leading to a steeper MIR slope. The sources that depart from these correlations have very low PAH equivalent width (EQW{sub 6.2{mu}m} < 0.1 {mu}m) consistent with their emission being dominated by an active galactic nucleus (AGN) in the MIR. These extremely low PAH EQW sources separate into two distinct types: relatively unobscured sources with a very hot dust component (and thus very shallow MIR slopes) and heavily dust obscured nuclei with a steep temperature gradient. The most heavily dust obscured sources are also the most compact in their MIR

  14. The spatially-resolved correlation between [NII] 205 {\\mu}m line emission and the 24 {\\mu}m continuum in nearby galaxies

    CERN Document Server

    Hughes, T M; Schirm, M R P; Parkin, T J; Wu, R; De Looze, I; Wilson, C D; Viaene, S; Bendo, G J; Boselli, A; Cormier, D; Ibar, E; Karczewski, O Ł; Lu, N; Spinoglio, L

    2016-01-01

    A correlation between the 24 {\\mu}m continuum and the [NII] 205 {\\mu}m line emission may arise if both quantities trace the star formation activity on spatially-resolved scales within a galaxy, yet has so far only been observed in the nearby edge-on spiral galaxy NGC 891. We therefore assess whether the [NII] 205 - 24 {\\mu}m emission correlation has some physical origin or is merely an artefact of line-of-sight projection effects in an edge-on disc. We search for the presence of a correlation in Herschel and Spitzer observations of two nearby face-on galaxies, M51 and M83, and the interacting Antennae galaxies NGC 4038 and 4039. We show that not only is this empirical relationship also observed in face-on galaxies, but also that the correlation appears to be governed by the star formation rate (SFR). Both the nuclear starburst in M83 and the merger-induced star formation in NGC 4038/9 exhibit less [NII] emission per unit SFR surface density than the normal star-forming discs. These regions of intense star for...

  15. Chandra ACIS Survey of X-ray Point Sources in Nearby Galaxies. II. X-ray Luminosity Functions and Ultraluminous X-ray Sources

    CERN Document Server

    Wang, Song; Liu, Jifeng; Bregman, Joel N

    2016-01-01

    Based on the recently completed {\\it Chandra}/ACIS survey of X-ray point sources in nearby galaxies, we study the X-ray luminosity functions (XLFs) for X-ray point sources in different types of galaxies and the statistical properties of ultraluminous X-ray sources (ULXs). Uniform procedures are developed to compute the detection threshold, to estimate the foreground/background contamination, and to calculate the XLFs for individual galaxies and groups of galaxies, resulting in an XLF library for 343 galaxies of different types. With the large number of surveyed galaxies, we have studied the XLFs and ULX properties across different host galaxy types, and confirm with good statistics that the XLF slope flattens from lenticular ($\\alpha\\sim1.50\\pm0.07$) to elliptical ($\\sim1.21\\pm0.02$), to spirals ($\\sim0.80\\pm0.02$), to peculiars ($\\sim0.55\\pm0.30$), and to irregulars ($\\sim0.26\\pm0.10$). The XLF break dividing the neutron star and black hole binaries is also confirmed, albeit at quite different break luminosi...

  16. CO Multi-line Imaging of Nearby Galaxies (COMING): I. Physical properties of molecular gas in the barred spiral galaxy NGC 2903

    CERN Document Server

    Muraoka, Kazuyuki; Kuno, Nario; Nakai, Naomasa; Nakanishi, Hiroyuki; Takeda, Miho; Yanagitani, Kazuki; Kaneko, Hiroyuki; Miyamoto, Yusuke; Kishida, Nozomi; Hatakeyama, Takuya; Umei, Michiko; Tanaka, Takahiro; Tomiyasu, Yuto; Saita, Chey; Ueno, Saeko; Matsumoto, Naoko; Salak, Dragan; Morokuma, Kana

    2016-01-01

    We present simultaneous mappings of J=1-0 emission of 12CO, 13CO, and C18O molecules toward the whole disk (8' x 5' or 20.8 kpc x 13.0 kpc) of the nearby barred spiral galaxy NGC 2903 with the Nobeyama Radio Observatory 45-m telescope at an effective angular resolution of 20" (or 870 pc). We detected 12CO(J=1-0) emission over the disk of NGC 2903. In addition, significant 13CO(J=1-0) emission was found at the center and bar-ends, whereas we could not detect any significant C18O(J=1-0) emission. In order to improve the signal-to-noise ratio of CO emission and to obtain accurate line ratios of 12CO(J=2-1)/12CO(J=1-0) ($R_{2-1/1-0}$) and 13CO(J=1-0)/12CO(J=1-0) ($R_{13/12}$), we performed the stacking analysis for our 12CO(J=1-0), 13CO(J=1-0), and archival 12CO(J=2-1) spectra with velocity-axis alignment in nine representative regions of NGC 2903. We successfully obtained the stacked spectra of the three CO lines, and could measure averaged $R_{2-1/1-0}$ and $R_{13/12}$ with high significance for all the regions...

  17. CARMA Survey Toward Infrared-bright Nearby Galaxies (STING) II: Molecular Gas Star Formation Law and Depletion Time Across the Blue Sequence

    CERN Document Server

    Rahman, Nurur; Xue, Rui; Wong, Tony; Leroy, Adam K; Walter, Fabian; Bigiel, Frank; Rosolowsky, Erik; Fisher, David B; Vogel, Stuart N; Blitz, Leo; West, Andrew A; Ott, Juergen

    2011-01-01

    We present an analysis of the relationship between molecular gas and current star formation rate surface density at sub-kpc and kpc scales in a sample of 14 nearby star-forming galaxies. Measuring the relationship in the bright, high molecular gas surface density ($\\Shtwo\\gtrsim$20 \\msunpc) regions of the disks to minimize the contribution from diffuse extended emission, we find an approximately linear relation between molecular gas and star formation rate surface density, $\

  18. The Sloan Lens ACS Survey. VII. Elliptical Galaxy Scaling Laws from Direct Observational Mass Measurements

    CERN Document Server

    Bolton, Adam S; Koopmans, Leon V E; Gavazzi, Raphael; Moustakas, Leonidas A; Burles, Scott; Schlegel, David J; Wayth, Randall

    2008-01-01

    We use a sample of 53 massive early-type strong gravitational lens galaxies with well-measured redshifts (ranging from z=0.06 to 0.36) and stellar velocity dispersions (between 175 and 400 km/s) from the Sloan Lens ACS (SLACS) Survey to derive numerous empirical scaling relations. The ratio between central stellar velocity dispersion and isothermal lens-model velocity dispersion is nearly unity within errors. The SLACS lenses define a fundamental plane (FP) that is consistent with the FP of the general population of early-type galaxies. We measure the relationship between strong-lensing mass M_lens within one-half effective radius (R_e/2) and the dimensional mass variable M_dim = G^-1 sigma_e2^2 R_e/2 to be log_10 [M_lens/10^11 M_Sun] = (1.03 +/- 0.04) log_10 [M_dim/10^11 M_Sun] + (0.54 +/- 0.02) (where sigma_e2 is the projected stellar velocity dispersion within R_e/2). The near-unity slope indicates that the mass-dynamical structure of massive elliptical galaxies is independent of mass, and that the "tilt" ...

  19. Ultra Compact Dwarf galaxies in Abell 1689: a photometric study with the ACS

    CERN Document Server

    Mieske, S; Benítez, N; Coe, D; Blakeslee, J P; Zekser, K; Ford, H; Broadhurst, T J; Illingworth, G D; Hartig, G F; Clampin, M; Ardila, D R; Bartko, F; Bouwens, R J; Brown, R A; Burrows, C J; Cheng, E S; Cross, N J G; Feldman, P D; Franx, M; Golimowski, D A; Goto, T; Gronwall, C; Holden, B; Homeier, N; Kimble, R A; Krist, J E; Lesser, M P; Martel, A R; Menanteau, F; Meurer, G R; Miley, G K; Postman, M; Rosati, P; Sirianni, M; Sparks, W B; Tran, H D; Tsvetanov, Z I; White, R L; Zheng, W

    2004-01-01

    The properties of Ultra Compact Dwarf (UCD) galaxy candidates in Abell 1689 (z=0.183) are investigated, based on deep high resolution ACS images. A UCD candidate has to be unresolved, have i26.8 mag, the radial and luminosity distribution of the UCD candidates can be explained well by Abell 1689's globular cluster (GC) system. For i<26.8 mag, there is an overpopulation of 15 +/- 5 UCD candidates with respect to the GC luminosity function. For i<26 mag, the radial distribution of UCD candidates is more consistent with the dwarf galaxy population than with the GC system of Abell 1689. The UCD candidates follow a color-magnitude trend with a slope similar to that of Abell 1689's genuine dwarf galaxy population, but shifted fainter by about 2-3 mag. Two of the three brightest UCD candidates (M_V ~ -17 mag) are slightly resolved. At the distance of Abell 1689, these two objects would have King-profile core radii of ~35 pc and r_eff ~300 pc, implying luminosities and sizes 2-3 times those of M32's bulge. Addi...

  20. Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction

    Science.gov (United States)

    Pratt, G. W.; Arnaud, M.; Piffaretti, R.; Böhringer, H.; Ponman, T. J.; Croston, J. H.; Voit, G. M.; Borgani, S.; Bower, R. G.

    2010-02-01

    We examine the radial entropy distribution and its scaling using 31 nearby galaxy clusters from the representative XMM-Newton cluster structure survey (REXCESS), a sample in the temperature range 2-9 keV selected in X-ray luminosity only, with no bias toward any particular morphological type. The entropy profiles are robustly measured at least out to R1000 in all systems and out to R500 in thirteen systems. Compared to theoretical expectations from non-radiative cosmological simulations, the observed distributions show a radial and mass-dependent excess entropy, such that the excess is greater and extends to larger radii in lower mass systems. At R500, the mass dependence and entropy excess are both negligible within the large observational and theoretical uncertainties. Mirroring this behaviour, the scaling of gas entropy is shallower than self-similar in the inner regions, but steepens with radius, becoming consistent with self-similar at R500. There is a large dispersion in scaled entropy in the inner regions, apparently linked to the presence of cool cores and dynamical activity; at larger radii the dispersion decreases by approximately a factor of two to 30 per cent, and the dichotomy between subsamples disappears. There are two peaks in the distribution of both inner slope and, after parameterising the profiles with a power law plus constant model, in central entropy K0. However, we are unable to distinguish between a bimodal or a left-skewed distribution of K0 with the present data. The distribution of outer slopes is unimodal with a median value of 0.98, and there is a clear correlation of outer slope with temperature. Renormalising the dimensionless entropy profiles by the gas mass fraction profile fgas (cool core.

  1. Optical observations of the nearby galaxy IC342 with narrow band [SII] and hα filters. II - detection of 16 optically-identified supernova remnant candidates

    Directory of Open Access Journals (Sweden)

    Vučetić M.M.

    2015-01-01

    Full Text Available We present the detection of 16 optical supernova remnant (SNR candidates in the nearby spiral galaxy IC342. The candidates were detected by applying the [Sii]/Hα ratio criterion on observations made with the 2 m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper, we report the coordinates, diameters, Hα and [S ii] fluxes for 16 SNRs detected in two fields of view in the IC342 galaxy. Also, we estimate the contamination of total Hα flux from SNRs in the observed portion of IC342 to be 1.4%. This would represent the fractional error when the star formation rate (SFR for this galaxy is derived from the total galaxy’s Hα emission.

  2. The Sloan Lens ACS survey. IV. The mass density profile of early-type galaxies out to 100 effective radii

    NARCIS (Netherlands)

    Gavazzi, Raphael; Treu, Tommaso; Rhodes, Jason D.; Koopmans, Leon V. E.; Bolton, Adam S.; Burles, Scott; Massey, Richard J.; Moustakas, Leonidas A.

    2007-01-01

    We present a weak-lensing analysis of 22 early-type (strong) lens galaxies, based on deep HST images obtained as part of the Sloan Lens ACS Survey. Using advanced techniques to control systematic uncertainties, we show that weak-lensing signal is detected out to similar to 300 h(-1) kpc (at the mean

  3. Star formation properties in barred galaxies. III. Statistical study of bar-driven secular evolution using a sample of nearby barred spirals

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhi-Min; Wu, Hong [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Cao, Chen, E-mail: zmzhou@bao.ac.cn, E-mail: hwu@bao.ac.cn, E-mail: caochen@sdu.edu.cn [School of Space Science and Physics, Shandong University at Weihai, Weihai, Shandong 264209 (China)

    2015-01-01

    Stellar bars are important internal drivers of secular evolution in disk galaxies. Using a sample of nearby spiral galaxies with weak and strong bars, we explore the relationships between the star formation feature and stellar bars in galaxies. We find that galaxies with weak bars tend coincide with low concentrical star formation activity, while those with strong bars show a large scatter in the distribution of star formation activity. We find enhanced star formation activity in bulges toward stronger bars, although not predominantly, consistent with previous studies. Our results suggest that different stages of the secular process and many other factors may contribute to the complexity of the secular evolution. In addition, barred galaxies with intense star formation in bars tend to have active star formation in their bulges and disks, and bulges have higher star formation densities than bars and disks, indicating the evolutionary effects of bars. We then derived a possible criterion to quantify the different stages of the bar-driven physical process, while future work is needed because of the uncertainties.

  4. The selective effect of environment on the atomic and molecular gas-to-dust ratio of nearby galaxies in the Herschel Reference Survey

    CERN Document Server

    Cortese, L; Boselli, A; Catinella, B; Ciesla, L; Hughes, T M; Baes, M; Bendo, G J; Boquien, M; de Looze, I; Smith, M W L; Spinoglio, L; Viaene, S

    2016-01-01

    We combine dust, atomic (HI) and molecular (H$_{2}$) hydrogen mass measurements for 176 galaxies in the Herschel Reference Survey to investigate the effect of environment on the gas-to-dust mass ($M_{\\rm gas}/M_{\\rm dust}$) ratio of nearby galaxies. We find that, at fixed stellar mass, the average $M_{\\rm gas}/M_{\\rm dust}$ ratio varies by no more than a factor of $\\sim$2 when moving from field to cluster galaxies, with Virgo galaxies being slightly more dust rich (per unit of gas) than isolated systems. Remarkably, once the molecular and atomic hydrogen phases are investigated separately, we find that \\hi-deficient galaxies have at the same time lower $M_{\\rm HI}/M_{\\rm dust}$ ratio but higher $M_{\\rm H_{2}}/M_{\\rm dust}$ ratio than \\hi-normal systems. In other words, they are poorer in atomic but richer in molecular hydrogen if normalized to their dust content. By comparing our findings with the predictions of theoretical models, we show that the opposite behavior observed in the $M_{\\rm HI}/M_{\\rm dust}$ a...

  5. BLUE LUMINOUS STARS IN NEARBY GALAXIES-UIT 005: A POSSIBLE LINK TO THE LUMINOUS BLUE VARIABLE STAGE

    International Nuclear Information System (INIS)

    A detailed study of the blue supergiant UIT 005 (B2-2.5Ia+) in M 33 is presented. The results of our quantitative spectral analysis indicate that the star is a very luminous (log L/Lsun ∼ 5.9 dex) and massive (M ∼ 50 Msun) object, showing a very high nitrogen-to-oxygen ratio in its surface (N/O∼8, by mass). Based on the derived Mg and Si abundances, we argue that this high N/O ratio cannot be the result of an initial low O content due to its location on the disk of M 33, a galaxy known to present a steep metallicity gradient. In combination with the He abundance, the most plausible interpretation is that UIT 005 is in an advanced stage of evolution, showing in its surface N enrichment and O depletion resulting from mixing with CNO processed material from the stellar interior. A comparison with the predictions of current stellar evolutionary models indicates that there are significant discrepancies, in particular with regard to the degree of chemical processing, with the models predicting a much lower degree of O depletion than observed. At the same time, the mass-loss rate derived in our analysis is an order of magnitude lower than the values considered in the evolutionary calculations. Based on a study of the surrounding stellar population and the nearby cluster, NGC 588, using Hubble Space Telescope/WFPC2 photometry, we suggest that UIT 005 could be in fact a runaway star from this cluster. Regardless of its origin, the derived parameters place the star in a region of the Hertzsprung-Russell diagram where luminous blue variables (LBVs) are usually found, but we find no evidence supporting photometric or spectroscopic variability, except for small Hα changes, otherwise observed in Galactic B-type supergiants. Whether UIT 005 is an LBV in a dormant state or a regular blue supergiant could not be discerned in this study. Subsequent monitoring would help us to improve our knowledge of the more massive stars, bridging the gap between regular and more exotic

  6. The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey IX: $^{12}$CO $J=3\\to2$ Observations of NGC 2976 and NGC 3351

    CERN Document Server

    Tan, Boon-Kok; Rigopoulou, D; Warren, B E; Wilson, C D; Attewell, D; Azimlu, M; Bendo, G J; Butner, H M; Brinks, E; Chanial, P; Clements, D L; Heesen, V; Israel, F; Knapen, J H; Matthews, H E; Mortier, A M J; Mühle,; Sánchez-Gallego, J R; Tilanus, R P J; Usero, A; van der Werf, P; Zhu, M

    2013-01-01

    We present $^{12}$CO \\textit{J=3$\\rightarrow$2} maps of NGC 2976 and NGC 3351 obtained with the James Clerk Maxwell Telescope (JCMT), both early targets of the JCMT Nearby Galaxy Legacy Survey (NGLS). We combine the present observations with $^{12}$CO \\textit{J=1$\\rightarrow$0} data and find that the computed $^{12}$CO \\textit{J=3$\\rightarrow$2} to $^{12}$CO \\textit{J=1$\\rightarrow$0} line ratio ($R_{31}$) agrees with values measured in other NGLS field galaxies. We compute the M$_{\\rm{H_2}}$ value and find that it is robust against the value of $R_{31}$ used. Using \\textsc{Hi} data from the The \\textsc{Hi} Nearby Galaxy Survey (THINGS) survey, we find a tight correlation between surface density of H$_2$ and star formation rate density for NGC 3351 when $^{12}$CO \\textit{J=3$\\rightarrow$2} data are used. Finally, we compare the $^{12}$CO \\textit{J=3$\\rightarrow$2} intensity with the PAH 8 $\\mu$m surface brightness and find a good correlation in the high surface brightness regions. We extend this study to incl...

  7. The ACS LCID project VII: the blue stragglers population in the isolated dSph galaxies Cetus and Tucana

    CERN Document Server

    Monelli, M; Mapelli, M; Bernard, E J; Aparicio, A; Skillman, E D; Stetson, P B; Gallart, C; Hidalgo, S L; Mayer, L; Tolstoy, E

    2011-01-01

    We present the first investigation of the Blue Straggler star (BSS) population in two isolated dwarf spheroidal galaxies of the Local Group, Cetus and Tucana. Deep HST/ACS photometry allowed us to identify samples of 940 and 1214 candidates, respectively. The analysis of the star formation histories of the two galaxies suggests that both host a population of BSSs. Specifically, if the BSS candidates are interpreted as young main sequence stars, they do not conform to their galaxy's age-metallicity relationship. The analysis of the luminosity function and the radial distributions support this conclusion, and suggest a non-collisional mechanism for the BSS formation, from the evolution of primordial binaries. This scenario is also supported by the results of new dynamical simulations presented here. Both galaxies coincide with the relationship between the BSS frequency and the absolute visual magnitude Mv found by Momany et al (2007). If this relationship is confirmed by larger sample, then it could be a valuab...

  8. The ACS Fornax Cluster Survey. VI. The Nuclei of Early-Type Galaxies in the Fornax Cluster

    CERN Document Server

    Turner, Monica L; Ferrarese, Laura; Jordan, Andres; Blakeslee, John P; Mei, Simona; Peng, Eric W; West, Michael J

    2012-01-01

    The Advanced Camera for Surveys (ACS) Fornax Cluster Survey is a Hubble Space Telescope program to image 43 early-type galaxies in the Fornax cluster, using the F475W and F850LP bandpasses of the ACS. We employ both 1D and 2D techniques to characterize the properties of the stellar nuclei in these galaxies, defined as the central "luminosity excesses" relative to a Sersic model fitted to the underlying host. We find 72+/-13% of our sample (31 galaxies) to be nucleated, with only three of the nuclei offset by more than 0.5" from their galaxy photocenter, and with the majority of nuclei having colors bluer than their hosts. The nuclei are observed to be larger, and brighter, than typical Fornax globular clusters, and to follow different structural scaling relations. A comparison of our results to those from the ACS Virgo Cluster Survey reveals striking similarities in the properties of the nuclei belonging to these different environments. We briefly review a variety of proposed formation models and conclude tha...

  9. CO Multi-line Imaging of Nearby Galaxies (COMING). I. Physical properties of molecular gas in the barred spiral galaxy NGC 2903

    Science.gov (United States)

    Muraoka, Kazuyuki; Sorai, Kazuo; Kuno, Nario; Nakai, Naomasa; Nakanishi, Hiroyuki; Takeda, Miho; Yanagitani, Kazuki; Kaneko, Hiroyuki; Miyamoto, Yusuke; Kishida, Nozomi; Hatakeyama, Takuya; Umei, Michiko; Tanaka, Takahiro; Tomiyasu, Yuto; Saita, Chey; Ueno, Saeko; Matsumoto, Naoko; Salak, Dragan; Morokuma-Matsui, Kana

    2016-10-01

    We present simultaneous mappings of J = 1-0 emission of 12CO, 13CO, and C18O molecules toward the whole disk (8' × 5' or 20.8 kpc × 13.0 kpc) of the nearby barred spiral galaxy NGC 2903 with the Nobeyama Radio Observatory 45 m telescope at an effective angular resolution of 20″ (or 870 pc). We detected 12CO(J = 1-0) emission over the disk of NGC 2903. In addition, significant 13CO(J = 1-0) emission was found at the center and bar-ends, whereas we could not detect any significant C18O(J = 1-0) emission. In order to improve the signal-to-noise ratio of CO emission and to obtain accurate line ratios of 12CO(J = 2-1)/12CO(J = 1-0) (R2-1/1-0) and 13CO(J = 1-0)/12CO(J = 1-0) (R13/12), we performed the stacking analysis for our 12CO(J = 1-0), 13CO(J = 1-0), and archival 12CO(J = 2-1) spectra with velocity axis alignment in nine representative regions of NGC 2903. We successfully obtained the stacked spectra of the three CO lines, and could measure averaged R2-1/1-0 and R13/12 with high significance for all the regions. We found that both R2-1/1-0 and R13/12 differ according to the regions, which reflects the difference in the physical properties of molecular gas, i.e., density (n_H_2) and kinetic temperature (TK). We determined n_H_2 and TK using R2-1/1-0 and R13/12 based on the large velocity gradient approximation. The derived n_H_2 ranges from ˜1000 cm-3 (in the bar, bar-ends, and spiral arms) to 3700 cm-3 (at the center) and the derived TK ranges from 10 K (in the bar and spiral arms) to 30 K (at the center). We examined the dependence of star formation efficiencies (SFEs) on n_H_2 and TK, and found a positive correlation between SFE and n_H_2 with correlation coefficient for the least-squares power-law fit R2 of 0.50. This suggests that molecular gas density governs the spatial variations in SFEs.

  10. The Asymptotic Giant Branch and the Tip of the Red Giant Branch as Probes of Star Formation History: The Nearby Dwarf Irregular Galaxy KKH 98

    OpenAIRE

    Melbourne, J.; Williams, B.; Dalcanton, J.; Ammons, S. M.; Max, C.; Koo, D.C.; Girardi, Leo; Dolphin, A.

    2010-01-01

    We investigate the utility of the asymptotic giant branch (AGB) and the red giant branch (RGB) as probes of the star formation history (SFH) of the nearby (D=2.5 Mpc) dwarf irregular galaxy, KKH 98. Near-infrared (IR) Keck Laser Guide Star Adaptive Optics (AO) images resolve 592 IR bright stars reaching over 1 magnitude below the Tip of the Red Giant Branch. Significantly deeper optical (F475W and F814W) Hubble Space Telescope images of the same field contain over 2500 stars, reaching to the ...

  11. The Sloan-Lens ACS Survey II: stellar populations and internal structure of early-type lens galaxies

    CERN Document Server

    Treu, T; Burles, S; Koopmans, L; Moustakas, L; Bolton, Adam; Burles, Scott; Koopmans, Leon; Moustakas, Leonidas; Treu, Tommaso

    2006-01-01

    We derive Fundamental Plane parameters of 15 early-type lens galaxies identified by the Sloan Lens ACS (SLACS) Survey. The size of the sample allows us to investigate for the first time the distribution of lens galaxies in the FP space. After correcting for evolution, we find that lens galaxies occupy a subset of the local FP. The edge-on projection (approximately M vs M/L) is indistinguishable from that of normal early-type galaxies. However -- within the fundamental plane -- the lens galaxies appear to concentrate at the edge of the region populated by normal early-type galaxies. We show that this is a result of our selection procedure (approximately velocity dispersion sigma>240km/s). We conclude that SLACS lenses are a fair sample of high velocity dispersion early-type galaxies. By comparing the central stellar velocity dispersion that of the best fit lens model, we find == =1.01+-0.02 with 0.065 rms scatter. We conclude that within the Einstein radii the SLACS lenses are very well approximated by isother...

  12. Multi-wavelength observations of a rich galaxy cluster at z ~ 1: the HST/ACS colour-magnitude diagram

    CERN Document Server

    Santos, Joana S; Gobat, Raphael; Lidman, Chris; Dawson, Kyle; Perlmutter, Saul; Boehringer, Hans; Balestra, Italo; Mullis, Chris R; Fassbender, Rene; Kohnert, Jan; Lamer, Georg; Rettura, Alessandro; Rite, Charles; Schwope, Axel

    2009-01-01

    XMMU J1229+0151 is a rich galaxy cluster with redshift z=0.975, that was serendipitously detected in X-rays within the scope of the XMM-Newton Distant Cluster Project. HST/ACS observations in the i775 and z850 passbands, as well as VLT/FORS2 spectroscopy were further obtained, in addition to follow-up Near-Infrared (NIR) imaging in J- and Ks-bands with NTT/SOFI. We investigate the photometric, structural and spectral properties of the early-type galaxies in the high-redshift cluster XMMU J1229+0151. Source detection and aperture photometry are performed in the optical and NIR imaging. Galaxy morphology is inspected visually and by means of Sersic profile fitting to the 21 spectroscopically confirmed cluster members in the ACS field of view. The i775-z850 colour-magnitude relation (CMR) is derived with a method based on galaxy magnitudes obtained by fitting the surface brightness of the galaxies with Sersic models. The i775-z850 CMR of the spectroscopic members shows a very tight red-sequence with a zero point...

  13. AN INFRARED CENSUS OF DUST IN NEARBY GALAXIES WITH SPITZER (DUSTiNGS). II. DISCOVERY OF METAL-POOR DUSTY AGB STARS

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Martha L.; Sonneborn, George [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); McQuinn, Kristen B. W.; Gehrz, Robert D.; Skillman, Evan [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street SE, University of Minnesota, Minneapolis, MN 55455 (United States); Barmby, Pauline [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Bonanos, Alceste Z. [IAASARS, National Observatory of Athens, GR-15236 Penteli (Greece); Gordon, Karl D.; Meixner, Margaret [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Groenewegen, M. A. T. [Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels (Belgium); Lagadec, Eric [Laboratoire Lagrange, UMR7293, Univ. Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d' Azur, F-06300 Nice (France); Lennon, Daniel [ESA-European Space Astronomy Centre, Apdo. de Correo 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Marengo, Massimo [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); McDonald, Iain; Zijlstra, Albert [Jodrell Bank Centre for Astrophysics, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Sloan, G. C. [Astronomy Department, Cornell University, Ithaca, NY 14853-6801 (United States); Van Loon, Jacco Th., E-mail: martha.boyer@nasa.gov [Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG (United Kingdom)

    2015-02-10

    The DUSTiNGS survey (DUST in Nearby Galaxies with Spitzer) is a 3.6 and 4.5 μm imaging survey of 50 nearby dwarf galaxies designed to identify dust-producing asymptotic giant branch (AGB) stars and massive stars. Using two epochs, spaced approximately six months apart, we identify a total of 526 dusty variable AGB stars (sometimes called ''extreme'' or x-AGB stars; [3.6]-[4.5] > 0.1 mag). Of these, 111 are in galaxies with [Fe/H] < –1.5 and 12 are in galaxies with [Fe/H] < –2.0, making them the most metal-poor dust-producing AGB stars known. We compare these identifications to those in the literature and find that most are newly discovered large-amplitude variables, with the exception of ≈30 stars in NGC 185 and NGC 147, 1 star in IC 1613, and 1 star in Phoenix. The chemical abundances of the x-AGB variables are unknown, but the low metallicities suggest that they are more likely to be carbon-rich than oxygen-rich and comparisons with existing optical and near-IR photometry confirm that 70 of the x-AGB variables are confirmed or likely carbon stars. We see an increase in the pulsation amplitude with increased dust production, supporting previous studies suggesting that dust production and pulsation are linked. We find no strong evidence linking dust production with metallicity, indicating that dust can form in very metal-poor environments.

  14. The selective effect of environment on the atomic and molecular gas-to-dust ratio of nearby galaxies in the Herschel Reference Survey

    Science.gov (United States)

    Cortese, L.; Bekki, K.; Boselli, A.; Catinella, B.; Ciesla, L.; Hughes, T. M.; Baes, M.; Bendo, G. J.; Boquien, M.; de Looze, I.; Smith, M. W. L.; Spinoglio, L.; Viaene, S.

    2016-07-01

    We combine dust, atomic (H I) and molecular (H2) hydrogen mass measurements for 176 galaxies in the Herschel Reference Survey to investigate the effect of environment on the gas-to-dust mass (Mgas/Mdust) ratio of nearby galaxies. We find that, at fixed stellar mass, the average Mgas/Mdust ratio varies by no more than a factor of ˜2 when moving from field to cluster galaxies, with Virgo galaxies being slightly more dust rich (per unit of gas) than isolated systems. Remarkably, once the molecular and atomic hydrogen phases are investigated separately, we find that H I-deficient galaxies have at the same time lower M_{H I}/M_dust ratio but higher M_H2/M_dust ratio than H I-normal systems. In other words, they are poorer in atomic but richer in molecular hydrogen if normalized to their dust content. By comparing our findings with the predictions of theoretical models, we show that the opposite behaviour observed in the M_{H I}/M_dust and M_H2/M_dust ratios is fully consistent with outside-in stripping of the interstellar medium (ISM), and is simply a consequence of the different distribution of dust, H I and H2 across the disc. Our results demonstrate that the small environmental variations in the total Mgas/Mdust ratio, as well as in the gas-phase metallicity, do not automatically imply that environmental mechanisms are not able to affect the dust and metal content of the ISM in galaxies.

  15. HI emission and absorption in nearby, gas-rich galaxies II. -- sample completion and detection of intervening absorption in NGC 5156

    CERN Document Server

    Reeves, S N; Allison, J R; Koribalski, B S; Curran, S J; Pracy, M B; Phillips, C J; Bignall, H E; Reynolds, C

    2016-01-01

    We present the results of a survey for intervening 21cm HI absorption in a sample of 10 nearby, gas-rich galaxies selected from the HI Parkes All-Sky Survey (HIPASS). This follows the six HIPASS galaxies searched in previous work and completes our full sample. In this paper we searched for absorption along 17 sightlines with impact parameters between 6 and 46 kpc, making one new detection. We also obtained simultaneous HI emission-line data, allowing us to directly relate the absorption-line detection rate to the HI distribution. From this we find the majority of the non-detections in the current sample are because sightline does not intersect the HI disc of the galaxy at sufficiently high column density, but that source structure is also an important factor. The detected absorption-line arises in the galaxy NGC 5156 ($z = 0.01$) at an impact parameter of 19 kpc. The line is deep and narrow with an integrated optical depth of 0.82 km s$^{-1}$. High resolution Australia Telescope Compact Array (ATCA) images at...

  16. The VIRUS-P Exploration of Nearby Spiral Galaxies (VENGA): Spatially Resolved Gas-Phase Metallicity Distributions in Barred and Unbarred Spirals

    CERN Document Server

    Kaplan, Kyle F; Kewley, Lisa; Blanc, Guillermo A; Weinzirl, Tim; Song, Mimi; Drory, Niv; Luo, Rongxin; Bosch, Remco C E van den

    2016-01-01

    We present a study of the excitation conditions and metallicity of ionized gas ($Z_{\\rm gas}$) in eight nearby barred and unbarred spiral galaxies from the VIRUS-P Exploration of Nearby Galaxies (VENGA) survey, which provides high spatial sampling and resolution (median $\\sim$ 387 pc), large coverage from the bulge to outer disc, broad wavelength range (3600-6800 \\AA{}), and medium spectral resolution ($\\sim$ 120 km s$^{-1}$ at 5000 \\AA{}). Our results are: (1) We present high resolution gas excitation maps to differentiate between regions with excitation typical of Seyfert, LINER, or recent star formation. We find LINER-type excitation at large distances (3-10 kpc) from the centre, and associate this excitation with diffuse ionized gas (DIG). (2) After excluding spaxels dominated by Seyfert, LINER, or DIG, we produce maps with the best spatial resolution and sampling to date of the ionization parameter $q$, star formation rate, and $Z_{\\rm gas}$ using common strong line diagnostics. We find that isolated bar...

  17. ALFALFA Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo~P. II. Optical Imaging Observations

    CERN Document Server

    Rhode, Katherine L; Haurberg, Nathalie C; Van Sistine, Angela; Young, Michael D; Haynes, Martha P; Giovanelli, Riccardo; Cannon, John M; Skillman, Evan D; McQuinn, Kristen B W; Adams, Elizabeth A K

    2013-01-01

    We present results from ground-based optical imaging of a low-mass dwarf galaxy discovered by the ALFALFA 21-cm HI survey. Broadband (BVR) data obtained with the WIYN 3.5-m telescope at Kitt Peak National Observatory (KPNO) are used to construct color-magnitude diagrams of the galaxy's stellar population down to V_0 ~ 25. We also use narrowband H-alpha imaging from the KPNO 2.1-m telescope to identify an HII region in the galaxy. We use these data to constrain the distance to the galaxy to be between 1.5 and 2.0 Mpc. This places Leo P within the Local Volume but beyond the Local Group. Its properties are extreme: it is the lowest-mass system known that contains significant amounts of gas and is currently forming stars.

  18. Color-magnitude distribution of face-on nearby galaxies in Sloan digital sky survey DR7

    International Nuclear Information System (INIS)

    We have analyzed the distributions in the color-magnitude diagram (CMD) of a large sample of face-on galaxies to minimize the effect of dust extinctions on galaxy color. About 300,000 galaxies with log (a/b) < 0.2 and redshift z < 0.2 are selected from the Sloan Digital Sky Survey DR7 catalog. Two methods are employed to investigate the distributions of galaxies in the CMD, including one-dimensional (1D) Gaussian fitting to the distributions in individual magnitude bins and two-dimensional (2D) Gaussian mixture model (GMM) fitting to galaxies as a whole. We find that in the 1D fitting, two Gaussians are not enough to fit galaxies with the excess present between the blue cloud and the red sequence. The fitting to this excess defines the center of the green valley in the local universe to be (u – r)0.1 = –0.121M r, 0.1 – 0.061. The fraction of blue cloud and red sequence galaxies turns over around M r, 0.1 ∼ –20.1 mag, corresponding to stellar mass of 3 × 1010 M ☉. For the 2D GMM fitting, a total of four Gaussians are required, one for the blue cloud, one for the red sequence, and the additional two for the green valley. The fact that two Gaussians are needed to describe the distributions of galaxies in the green valley is consistent with some models that argue for two different evolutionary paths from the blue cloud to the red sequence.

  19. Color-magnitude distribution of face-on nearby galaxies in Sloan digital sky survey DR7

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Shuo-Wen; Feng, Long-Long [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Gu, Qiusheng; Huang, Song; Shi, Yong, E-mail: qsgu@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2014-05-20

    We have analyzed the distributions in the color-magnitude diagram (CMD) of a large sample of face-on galaxies to minimize the effect of dust extinctions on galaxy color. About 300,000 galaxies with log (a/b) < 0.2 and redshift z < 0.2 are selected from the Sloan Digital Sky Survey DR7 catalog. Two methods are employed to investigate the distributions of galaxies in the CMD, including one-dimensional (1D) Gaussian fitting to the distributions in individual magnitude bins and two-dimensional (2D) Gaussian mixture model (GMM) fitting to galaxies as a whole. We find that in the 1D fitting, two Gaussians are not enough to fit galaxies with the excess present between the blue cloud and the red sequence. The fitting to this excess defines the center of the green valley in the local universe to be (u – r){sub 0.1} = –0.121M {sub r,} 0{sub .1} – 0.061. The fraction of blue cloud and red sequence galaxies turns over around M {sub r,} {sub 0.1} ∼ –20.1 mag, corresponding to stellar mass of 3 × 10{sup 10} M {sub ☉}. For the 2D GMM fitting, a total of four Gaussians are required, one for the blue cloud, one for the red sequence, and the additional two for the green valley. The fact that two Gaussians are needed to describe the distributions of galaxies in the green valley is consistent with some models that argue for two different evolutionary paths from the blue cloud to the red sequence.

  20. Hubble Space Telescope ACS mosaic of the prototypical starburst galaxy M82

    CERN Document Server

    Mutchler, M; Christian, C A; Frattare, L M; Hamilton, F; Januszewski, W; Levay, Z G; Mountain, M; Noll, K S; Royle, P; Gallagher, J S; Puxley, P

    2006-01-01

    In March 2006, the Hubble Heritage Team obtained a large four-filter (B, V, I, and H-alpha) six-point mosaic dataset of the prototypical starburst galaxy NGC 3034 (M82), with the Advanced Camera for Surveys (ACS) onboard the Hubble Space Telescope (HST). The resulting color composite Heritage image was released in April 2006, to celebrate Hubble's 16th anniversary. Cycle 15 HST proposers were encouraged to submit General Observer and Archival Research proposals to complement or analyze this unique dataset. Since our M82 mosaics represent a significant investment of expert processing beyond the standard archival products, we will also release our drizzle combined FITS data as a High Level Science Product via the Multimission Archive at STScI (MAST) on December 31, 2006. This paper documents the key aspects of the observing program and image processing: calibration, image registration and combination (drizzling), and the rejection of cosmic rays and detector artifacts. Our processed FITS mosaics and related inf...

  1. INTEGRAL FIELD SPECTROSCOPY AND MULTI-WAVELENGTH IMAGING OF THE NEARBY SPIRAL GALAXY NGC 5668 : AN UNUSUAL FLATTENING IN METALLICITY GRADIENT

    Energy Technology Data Exchange (ETDEWEB)

    Marino, R. A.; Gil de Paz, A.; Castillo-Morales, A.; Perez-Gonzalez, P. G.; Gallego, J.; Zamorano, J. [CEI Campus Moncloa, UCM-UPM, Departamento de Astrofisica y CC. de la Atmosfera, Facultad de CC. Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Munoz-Mateos, J. C. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Sanchez, S. F. [Centro Astronomico Hispano Aleman, Calar Alto (CSIC-MPG), C/Jesus Durban Remon 2-2, E-04004 Almeria (Spain); Alonso-Herrero, A. [Instituto de Fisica de Cantabria, CSIC-UC, Avenida de los Castros s/n, 39005 Santander (Spain); Boissier, S., E-mail: ramarino@fis.ucm.es [Laboratoire dAstrophysique de Marseille, OAMP, Universite Aix-Marseille and CNRS UMR 6110, 38 rue Frederic Joliot-Curie, 13388 Marseille cedex 13 (France)

    2012-07-20

    We present an analysis of the full bidimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the Pmas fiber PAcK Integral Field Unit (IFU) at the Calar Alto observatory 3.5 m telescope. We make use of broadband imaging to provide further constraints on the evolutionary history of the galaxy. This data set will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that while inward of r {approx}36'' {approx} 4.4 kpc {approx} 0.36 (D{sub 25}/2) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r {approx} 36'' flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of {lambda} = 0.053 and v{sub c} = 167 km s{sup -1}, respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r {approx}36''. The same is true for the colors despite some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668.

  2. H I emission and absorption in nearby, gas-rich galaxies - II. Sample completion and detection of intervening absorption in NGC 5156

    Science.gov (United States)

    Reeves, S. N.; Sadler, E. M.; Allison, J. R.; Koribalski, B. S.; Curran, S. J.; Pracy, M. B.; Phillips, C. J.; Bignall, H. E.; Reynolds, C.

    2016-04-01

    We present the results of a survey for intervening 21 cm H I absorption in a sample of 10 nearby, gas-rich galaxies selected from the H I Parkes All-Sky Survey (HIPASS). This follows the six HIPASS galaxies searched in previous work and completes our full sample. In this paper, we searched for absorption along 17 sightlines with impact parameters between 6 and 46 kpc, making one new detection. We also obtained simultaneous H I emission-line data, allowing us to directly relate the absorption-line detection rate to the H I distribution. From this, we find the majority of the non-detections in the current sample are because sightline does not intersect the H I disc of the galaxy at sufficiently high column density, but that source structure is also an important factor. The detected absorption-line arises in the galaxy NGC 5156 (z = 0.01) at an impact parameter of 19 kpc. The line is deep and narrow with an integrated optical depth of 0.82 km s-1. High-resolution Australia Telescope Compact Array (ATCA) images at 5 and 8 GHz reveal that the background source is resolved into two components with a separation of 2.6 arcsec (500 pc at the redshift of the galaxy), with the absorption likely occurring against a single component. We estimate that the ratio of the spin temperature and covering factor, TS/f, is approximately 950 K in the outer disc of NGC 5156, but further observations using very long baseline interferometry would allow us to accurately measure the covering factor and spin temperature of the gas.

  3. The Luminosity Functions of the Galaxy Cluster MS1054-0321 at z=0.83 based on ACS Photometry

    CERN Document Server

    Goto, T; Cross, N J G; Illingworth, G D; Tran, K; Magee, D; Franx, M; Benítez, N; Bouwens, R J; Demarco, R; Ford, H C; Homeier, N L; Martel, A R; Menanteau, F; Clampin, M; Hartig, G F; Ardila, D R; Bartko, F; Blakeslee, J P; Bradley, L D; Broadhurst, T J; Brown, R A; Burrows, C J; Cheng, E S; Feldman, P D; Golimowski, D A; Gronwall, C; Holden, B; Infante, L; Jee, M J; Krist, J E; Lesser, M P; Mei, S; Meurer, G R; Miley, G K; Motta, V; Overzier, R; Rosati, P; Sirianni, M; Sparks, W B; Tran, H D; Tsvetanov, Z I; White, R L; Zheng, W; Zirm, A W; Goto, Tomotsugu; Postman, Marc; Cross, Nicholas J.G.

    2004-01-01

    We present new measurements of the galaxy luminosity function (LF) and its dependence on local galaxy density, color, morphology, and clustocentric radius for the massive $z=0.83$ cluster MS1054-0321. Our analyses are based on imaging performed with the ACS onboard the HST in the F606W, F775W and F850LP passbands and extensive spectroscopic data obtained with the Keck LRIS. Our main results are based on a spectroscopically selected sample of 143 cluster members with morphological classifications derived from the ACS observations. Our three primary findings are (1) the faint-end slope of the LF is steepest in the bluest filter, (2) the LF in the inner part of the cluster (or highest density regions) has a flatter faint-end slope, and (3) the fraction of early-type galaxies is higher at the bright end of the LF, and gradually decreases toward fainter magnitudes. These characteristics are consistent with those in local galaxy clusters, indicating that, at least in massive clusters, the common characteristics of ...

  4. The HST/ACS Coma Cluster Survey. VIII. Barred Disk Galaxies in the Core of the Coma Cluster

    CERN Document Server

    Marinova, Irina; Weinzirl, Tim; Erwin, Peter; Trentham, Neil; Ferguson, Henry C; Hammer, Derek; Brok, Mark den; Graham, Alister W; Carter, David; Balcells, Marc; Goudfrooij, Paul; Guzman, Rafael; Hoyos, Carlos; Mobasher, Bahram; Mouhcine, Mustapha; Peletier, Reynier F; Peng, Eric; Kleijn, Gijs Verdoes

    2012-01-01

    (ABRIDGED) We use high resolution (~0.1") F814W ACS images from the HST ACS Treasury survey of the Coma cluster at z~0.02 to study bars in massive disk galaxies (S0s), and in dwarf galaxies in the Coma core. Our study helps constrain the evolution of bars and disks in dense environments and provides a comparison point for studies in lower density environments and at higher redshifts. (1) We characterize the fraction and properties of bars in a sample of 32 bright (M_V 10^9.5 M_sun) S0 galaxies, which dominate the population of massive disk galaxies in the Coma core. Measuring the S0 bar fraction must be handled carefully, as the results depend on the method used: the bar fraction for bright S0s in the Coma core is 50%+/-11%, 65%+/-11%, and 60%+/-11% for three methods of bar detection: strict ellipse fit criteria, relaxed ellipse fit criteria, and visual classification. (2) We compare the S0 bar fraction across different environments (Coma core, A901/902, Virgo). We find that the bar fraction among bright S0 ...

  5. A low-luminosity type-1 QSO sample . IV. Molecular gas contents and conditions of star formation in three nearby Seyfert galaxies

    Science.gov (United States)

    Moser, Lydia; Krips, Melanie; Busch, Gerold; Scharwächter, Julia; König, Sabine; Eckart, Andreas; Smajić, Semir; García-Marin, Macarena; Valencia-S., Mónica; Fischer, Sebastian; Dierkes, Jens

    2016-03-01

    We present a pilot study of ~3'' resolution observations of low CO transitions with the Submillimeter Array in three nearby Seyfert galaxies, which are part of the low-luminosity quasi-stellar object (LLQSOs) sample consisting of 99 nearby (z = 0.06) type-1 active galactic nuclei (AGN) taken from the Hamburg/ESO quasi-stellar object (QSO) survey. Two sources were observed in 12CO(2-1) and 13CO(2-1) and the third in 12CO(3-2) and HCO+(4-3). None of the sources is detected in continuum emission. More than 80% of the 12CO detected molecular gas is concentrated within a diameter (FWHM) 1.5 × 109M⊙ and for the dust masses of Mdust> 1.6 × 106M⊙. The R21 = 12CO/13CO(2-1) line luminosity ratios show Galactic values of R21 ~ 5-7 in the outskirts and R21 ≳ 20 in the central region, similar to starbursts and (ultra)luminous infrared galaxies ((U)LIRGs; i.e. LIRGs and ULIRGs), implying higher temperatures and stronger turbulence. All three sources show indications of 12CO(2-1)/12CO(1-0) ratios of ~0.5, suggesting a cold or diffuse gas phase. Strikingly, the 12CO(3-2)/(1-0) ratio of ~1 also indicates a higher excited phase. Since these galaxies have high infrared luminosities of LIR ≥ 1011L⊙ and seem to contain a circumnuclear starburst with minimum surface densities of gas and star formation rate (SFR) around Σmol = 50-550 M⊙pc-2 and ΣSFR = 1.1-3.1 M⊙ kpc-2 yr-1, we conclude that the interstellar medium in the centers of these LIRG Seyferts is strongly affected by violent star formation and better described by the ULIRG mass conversion factor.

  6. The VIRUS-P Exploration of Nearby Galaxies (VENGA): spatially resolved gas-phase metallicity distributions in barred and unbarred spirals

    Science.gov (United States)

    Kaplan, Kyle F.; Jogee, Shardha; Kewley, Lisa; Blanc, Guillermo A.; Weinzirl, Tim; Song, Mimi; Drory, Niv; Luo, Rongxin; van den Bosch, Remco C. E.

    2016-10-01

    We present a study of the excitation conditions and metallicity of ionized gas (Zgas) in eight nearby barred and unbarred spiral galaxies from the VIRUS-P Exploration of Nearby Galaxies (VENGA) survey, which provides high spatial sampling and resolution (median ˜387 pc), large coverage from the bulge to outer disc, broad wavelength range (3600-6800 Å), and medium spectral resolution (˜120 km s-1 at 5000 Å). Our results are: (1) We present high resolution gas excitation maps to differentiate between regions with excitation typical of Seyfert, LINER, or recent star formation. We find LINER-type excitation at large distances (3-10 kpc) from the centre, and associate this excitation with diffuse ionized gas (DIG). (2) After excluding spaxels dominated by Seyfert, LINER, or DIG, we produce maps with the best spatial resolution and sampling to date of the ionization parameter q, star formation rate, and Zgas using common strong line diagnostics. We find that isolated barred and unbarred spirals exhibit similarly shallow Zgas profiles from the inner kpc out to large radii (7-10 kpc or 0.5-1.0 R25). This implies that if profiles had steeper gradients at earlier epochs, then the present-day bar is not the primary driver flattening gradients over time. This result contradicts earlier claims, but agrees with recent IFU studies. (3) The Zgas gradients in our z ˜ 0 massive spirals are markedly shallower, by ˜0.2 dex kpc-1, than published gradients for lensed lower mass galaxies at z ˜ 1.5-2.0. Cosmologically motivated hydrodynamical simulations best match this inferred evolution, but the match is sensitive to adopted stellar feedback prescriptions.

  7. The HST/ACS Coma Cluster Survey : X. Nuclear star clusters in low-mass early-type galaxies: scaling relations

    NARCIS (Netherlands)

    Brok, Mark den; Peletier, Reynier F.; Seth, Anil; Balcells, Marc; Dominguez, Lilian; Graham, Alister W.; Carter, David; Erwin, Peter; Ferguson, Henry C.; Goudfrooij, Paul; Guzman, Rafael; Hoyos, Carlos; Jogee, Shardha; Lucey, John; Phillipps, Steven; Puzia, Thomas; Valentijn, Edwin; Verdoes Kleijn, Gijsbert; Weinzirl, Tim

    2014-01-01

    We present scaling relations between structural properties of nuclear star clusters and their host galaxies for a sample of early-type dwarf galaxies observed as part of the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Coma Cluster Survey. We have analysed the light profiles of 200

  8. The HST/ACS Coma Cluster Survey - X. Nuclear star clusters in low-mass early-type galaxies : scaling relations

    NARCIS (Netherlands)

    den Brok, Mark; Peletier, Reynier F.; Seth, Anil; Balcells, Marc; Dominguez, Lilian; Graham, Alister W.; Carter, David; Erwin, Peter; Ferguson, Henry C.; Goudfrooij, Paul; Guzman, Rafael; Hoyos, Carlos; Jogee, Shardha; Lucey, John; Phillipps, Steven; Puzia, Thomas; Valentijn, Edwin; Kleijn, Gijs Verdoes; Weinzirl, Tim

    2014-01-01

    We present scaling relations between structural properties of nuclear star clusters and their host galaxies for a sample of early-type dwarf galaxies observed as part of the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Coma Cluster Survey. We have analysed the light profiles of 200

  9. Galaxy evolution in nearby groups. II. Galaxy evolution in nearby loose groups. II. Photometric and kinematic characterization of USGC U268 and USGC U376 group members in the Leo cloud

    CERN Document Server

    Marino, A; Rampazzo, R; Bianchi, L; Rosado, M; Bettoni, D; Galletta, G; Mazzei, P; Buson, L; Ambrocio-Cruz, P; Gabbasov, R F

    2012-01-01

    We present the photometric and kinematic characterization of two groups, USGC U268 and USGC U376 located in different regions of the Leo cloud. U268, composed of 10 catalogued members and 11 new added members, has a small fraction (~24%) of early-type galaxies (ETGs). U376 has 16 plus 8 new added members, with ~38% of ETGs. We find the presence of significant substructures in both groups suggesting that they are likely accreting galaxies. U268 is located in a more loose environment than U376. For each member galaxy, broad band integrated and surface photometry have been obtained in far-UV and near-UV with GALEX, and in u,g, r, i, z (SDSS) bands. H_alpha imaging and 2D high resolution kinematical data have been obtained using PUMA Scanning Fabry-Perot interferometer at the 2.12 m telescope in San Pedro M\\'artir, (Baja California, M\\'exico). We improved the galaxy classification and we detected morphological and kinematical distortions that may be connected to either on-going and/or past interaction/accretion e...

  10. The Nature of Nearby Counterparts to Intermediate-Redshift Luminous Compact Blue Galaxies. III. Interferometric Observations of Neutral Atomic and Molecular Gas

    CERN Document Server

    Garland, C A; Williams, J P; Guzmán, R; Castander, F J; Sage, L J

    2007-01-01

    We present the results of a VLA and OVRO-MMA follow-up to our single-dish surveys of the neutral atomic and molecular gas in a sample of nearby Luminous Compact Blue Galaxies (LCBGs). These luminous, blue, high surface brightness, starbursting galaxies were selected using criteria similar to that used to define LCBGs at higher redshifts. The surveys were undertaken to study the nature and evolutionary possibilities of LCBGs, using dynamical masses and gas depletion time scales as constraints. Here we present nearly resolved VLA H I maps of four LCBGs, as well as results from the literature for a fifth LCBG. In addition, we present OVRO-MMA maps of CO(J=1-0) in two of these LCBGs. We have used the resolved H I maps to separate the H I emission from target galaxies and their companions to improve the accuracy of our gas and dynamical mass estimates. For this sub-sample of LCBGs, we find that the dynamical masses measured with the single-dish telescope and interferometer are in agreement. However, we find that w...

  11. Investigating Nearby Star-Forming Galaxies in the Ultraviolet with HST/COS Spectroscopy. I: Spectral Analysis and Interstellar Abundance Determinations

    CERN Document Server

    James, Bethan L; Heckman, Timothy M; Sohn, Sangmo Tony; Wolfe, Michael A

    2014-01-01

    This is the first in a series of three papers describing a project with the Cosmic Origins Spectrograph on the Hubble Space Telescope to measure abundances of the neutral interstellar medium (ISM) in a sample of 9 nearby star-forming galaxies. The goal is to assess the (in)homogeneities of the multiphase ISM in galaxies where the bulk of metals can be hidden in the neutral phase, yet the metallicity is inferred from the ionized gas in the HII regions. The sample, spanning a wide range in physical properties, is to date the best suited to investigate the metallicity behavior of the neutral gas at redshift z=0. ISM absorption lines were detected against the far-ultraviolet spectra of the brightest star-forming region(s) within each galaxy. Here we report on the observations, data reduction, and analysis of these spectra. Column densities were measured by a multi-component line-profile fitting technique, and neutral-gas abundances were obtained for a wide range of elements. Several caveats were considered includ...

  12. The Stellar Spectral Features of Nearby Galaxies in the Near-Infrared: Tracers of Thermally-Pulsing Asymptotic Giant Branch Stars?

    CERN Document Server

    Riffel, Rogério; Martins, Lucimara P; Rodíguez-Ardila, Alberto; Ho, Luis C; Riffel, Rogemar A; Lira, Paulina; Martin, Omaira Gonzalez; Ruschel-Dutra, Daniel; Alonso-Herrero, Almudena; Flohic, Helene; McDermid, Richard M; Almeida, Cristina Ramos; Thanjavur, Karun; Winge, Claudia

    2015-01-01

    We analyze the stellar absorption features in high signal-to-noise ratio near-infrared (NIR) spectra of the nuclear region of 12 nearby galaxies, mostly spirals. The features detected in some or all of the galaxies in this sample are the TiO (0.843 $\\mu$m\\ and 0.886 $\\mu$m), VO (1.048 $\\mu$m), CN (1.1 $\\mu$m\\ and 1.4 $\\mu$m), H$\\rm _2$O (1.4 $\\mu$m\\ and 1.9 $\\mu$m) and CO (1.6 $\\mu$m\\ and 2.3 $\\mu$m) bands. The C$\\rm _2$ (1.17 $\\mu$m\\ and 1.76 $\\mu$m) bands are generally weak or absent, although C$\\rm _2$ (1.76 $\\mu$m) may be weakly present in the mean galaxy spectrum. A deep feature near 0.93 $\\mu$m, likely caused by CN, TiO and/or ZrO, is also detected in all objects. Fitting a combination of stellar spectra to the mean spectrum shows that the absorption features are produced by evolved stars: cool giants and supergiant stars in the early- or thermally-pulsing asymptotic giant branch (E-AGB or TP-AGB) phases. The high luminosity of TP-AGB stars, and the appearance of VO and ZrO features in the data, suggest...

  13. CO(J = 3-2) on-the-fly mapping of the nearby spiral galaxies NGC 628 and NGC 7793: Spatially resolved CO(J = 3-2) star-formation law

    Science.gov (United States)

    Muraoka, Kazuyuki; Takeda, Miho; Yanagitani, Kazuki; Kaneko, Hiroyuki; Nakanishi, Kouichiro; Kuno, Nario; Sorai, Kazuo; Tosaki, Tomoka; Kohno, Kotaro

    2016-04-01

    We present the results of CO(J = 3-2) on-the-fly mappings of two nearby non-barred spiral galaxies, NGC 628 and NGC 7793, with the Atacama Submillimeter Telescope Experiment at an effective angular resolution of 25″. We successfully obtained global distributions of CO(J = 3-2) emission over the entire disks at a sub-kpc resolution for both galaxies. We examined the spatially resolved (sub-kpc) relationship between CO(J = 3-2) luminosities (L^' }_CO(3-2)) and infrared (IR) luminosities (LIR) for NGC 628, NGC 7793, and M 83, and compared it with global luminosities of a JCMT (James Clerk Maxwell Telescope) Nearby Galaxy Legacy Survey sample. We found a striking linear L^' }_CO(3-2)-LIR correlation over the four orders of magnitude, and the correlation is consistent even with that for ultraluminous IR galaxies and submillimeter-selected galaxies. In addition, we examined the spatially resolved relationship between CO(J = 3-2) intensities (ICO(3-2)) and extinction-corrected star formation rates (SFRs) for NGC 628, NGC 7793, and M 83, and compared it with that for Giant Molecular Clouds in M 33 and 14 nearby galaxy centers. We found a linear ICO(3-2)-SFR correlation with ˜1 dex scatter. We conclude that the CO(J = 3-2) star-formation law (i.e., linear L^' }_CO(3-2)-LIR and ICO(3-2)-SFR correlations) is universally applicable to various types and spatial scales of galaxies; from spatially resolved nearby galaxy disks to distant IR-luminous galaxies, within ˜1 dex scatter.

  14. The HST/ACS Coma Cluster Survey IV. Intergalactic Globular Clusters and the Massive Globular Cluster System at the Core of the Coma Galaxy Cluster

    OpenAIRE

    Peng, Eric W.; Ferguson, Henry C.; Goudfrooij, Paul; Hammer, Derek; Lucey, John R.; Marzke, ; Ronald O.; Puzia, Thomas H.; Carter, David; Balcells, Marc; Bridges, Terry; Chiboucas, Kristin; del Burgo, Carlos; Graham, Alister W.; Guzman, Rafael; Hudson, Michael J.

    2011-01-01

    Intracluster stellar populations are a natural result of tidal interactions in galaxy clusters. Measuring these populations is difficult, but important for understanding the assembly of the most massive galaxies. The Coma cluster is one of the nearest truly massive galaxy clusters, and is host to a correspondingly large system of globular clusters (GCs). We use imaging from the HST/ACS Coma Cluster Survey to present the first definitive detection of a large population of intracluster GCs (IGC...

  15. UV-IR color profiles of the outer regions of 2K nearby S$^{4}$G galaxies

    CERN Document Server

    Bouquin, Alexandre Y K

    2016-01-01

    We present our new, spatially-resolved, photometry in FUV and NUV from images obtained by GALEX, and IRAC1 (3.6 $\\mu$m) photometry obtained by the Spitzer Space Telescope. We analyzed the surface brightness profiles $\\mu_{\\rm{FUV}}$, $\\mu_{\\rm{NUV}}$, $\\mu_{[3.6]}$, as well as the radial evolution of the (FUV-NUV), (FUV - [3.6]), and (NUV - [3.6]) colors in the Spitzer Survey of Stellar Structures in Galaxies (S$^{4}$G) galaxies (d$$50%) of intermediary GALEX Green Valley (GGV) galaxies' outer disks are becoming redder. An outside-in quenching mechanism such as environmentally-related mechanisms such as starvation or ram-pressure-stripping could explain our results.

  16. Galaxy Zoo: The properties of merging galaxies in the nearby Universe - local environments, colours, masses, star-formation rates and AGN activity

    CERN Document Server

    Darg, D W; Lintott, C J; Schawinski, K; Sarzi, M; Bamford, S; Silk, J; Andreescu, D; Murray, P; Nichol, R C; Raddick, M J; Slosar, A; Szalay, A S; Thomas, D; Vandenberg, J

    2009-01-01

    Following the study of Darg et al. (2009; hereafter D09a) we explore the environments, optical colours, stellar masses, star-formation and AGN activity in a sample of 3003 merging galaxies drawn from the SDSS using the Galaxy Zoo project. While D09a found that the spiral-to-elliptical ratio in (major) mergers appeared higher than that of the global galaxy population, no significant differences are found between the environmental distributions of mergers and a randomly selected control sample. This makes the high occurrence of spirals in mergers unlikely to be an environmental effect and must, therefore, arise from differing time-scales of detectability for spirals and ellipticals. We find that merging galaxies have a wider spread in colour than the global galaxy population, with a significant blue tail resulting from intense star-formation in spiral mergers. Galaxies classed as star-forming using their emission-line properties have average star-formation rates approximately doubled by the merger process thoug...

  17. THE ACS VIRGO CLUSTER SURVEY. XVII. THE SPATIAL ALIGNMENT OF GLOBULAR CLUSTER SYSTEMS WITH EARLY-TYPE HOST GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qiushi; Peng, Eric W. [Department of Astronomy, Peking University, Beijing 100871 (China); Blakeslee, John P.; Cote, Patrick; Ferrarese, Laura [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Jordan, Andres [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Mei, Simona [University of Paris 7 Denis Diderot, F-75205 Paris Cedex 13 (France); West, Michael J., E-mail: peng@pku.edu.cn [Maria Mitchell Observatory, 4 Vestal Street, Nantucket, MA 02554 (United States)

    2013-06-01

    We study the azimuthal distribution of globular clusters (GCs) in early-type galaxies and compare them to their host galaxies using data from the ACS Virgo Cluster Survey. We find that in host galaxies with visible elongation ({epsilon} > 0.2) and intermediate to high luminosities (M{sub z} < -19), the GCs are preferentially aligned along the major axis of the stellar light. The red (metal-rich) GC subpopulations show strong alignment with the major axis of the host galaxy, which supports the notion that these GCs are associated with metal-rich field stars. The metal-rich GCs in lenticular galaxies show signs of being more strongly associated with disks rather than bulges. Surprisingly, we also find that the blue (metal-poor) GCs can also show the same correlation. If the metal-poor GCs are part of the early formation of the halo and built up through mergers, then our results support a picture where halo formation and merging occur anisotropically, and that the present-day major axis is an indicator of the preferred merging axis.

  18. Two Populations of Old Star Clusters in the Spiral Galaxy M101 Based on HST/ACS Observations

    CERN Document Server

    Simanton, Lesley A; Whitmore, Bradley C

    2015-01-01

    We present a new photometric catalog of 326 candidate globular clusters (GCs) in the nearby spiral galaxy M101, selected from B, V, and I Hubble Space Telescope Advanced Camera for Surveys images. The luminosity function (LF) of these clusters has an unusually large number of faint sources compared with GCLFs in many other spiral galaxies. Accordingly, we separate and compare the properties of "bright" (M_V -6.5; one magnitude fainter than the expected GC peak) clusters within our sample. The LF of the bright clusters is well fit by a peaked distribution similar to those observed in the Milky Way (MW) and other galaxies. These bright clusters also have similar size (r_{eff}) and spatial distributions as MW GCs. The LF of the faint clusters, on the other hand, is well described by a power law, dN(L_V)/dL_V proportional to L_V^alpha with alpha = -2.6 plus or minus 0.3, similar to those observed for young and intermediate-age cluster systems in star forming galaxies. We find that the faint clusters have larger ...

  19. The VIRUS-P Exploration of Nearby Galaxies (VENGA): Radial Gas Inflow and Shock Excitation in NGC 1042

    Science.gov (United States)

    Luo, Rongxin; Hao, Lei; Blanc, Guillermo A.; Jogee, Shardha; van den Bosch, Remco C. E.; Weinzirl, Tim

    2016-06-01

    NGC 1042 is a late-type bulgeless disk galaxy that hosts low-luminosity active galactic nuclei (AGNs) coincident with a massive nuclear star cluster. In this paper, we present the integral field spectroscopy studies of this galaxy, based on the data obtained with the Mitchell spectrograph on the 2.7 m Harlan J. Smith telescope. In the central 100-300 pc region of NGC 1042, we find a circumnuclear ring structure of gas with enhanced ionization, which we suggest is mainly induced by shocks. Combining this with the harmonic decomposition analysis of the velocity field of the ionized gas, we propose that the shocked gas is the result of gas inflow driven by the inner spiral arms. The inflow velocity is ˜ 32+/- 10 {km} {{{s}}}-1, and the estimated mass-inflow rate is ˜ 1.1+/- 0.3× {10}-3 {M}⊙ {{yr}}-1. The mass-inflow rate is about one hundred times the black hole’s mass-accretion rate (˜ 1.4× {10}-5 {M}⊙ {{yr}}-1) and slightly larger than the star-formation rate in the nuclear star cluster (7.94× {10}-4 {M}⊙ {{yr}}-1), implying that the inflow material is enough to feed both the AGN activity and star formation in the nuclear star cluster. Our study highlights that secular evolution can be important in late-type unbarred galaxies like NGC 1042.

  20. Modeling the Effects of Star Formation Histories on Halpha and Ultra-Violet Fluxes in Nearby Dwarf Galaxies

    CERN Document Server

    Weisz, Daniel R; Johnson, L Clifton; Skillman, Evan D; Lee, Janice C; Kennicutt, Robert C; Calzetti, Daniela; van Zee, Liese; Bothwell, Matthew; Dalcanton, Julianne J; Dale, Daniel A; Williams, Benjamin F

    2011-01-01

    We consider the effects of non-constant star formation histories (SFHs) on Halpha and GALEX far ultra-violet (FUV) star formation rate (SFR) indicators. Under the assumption of a fully populated Chabrier IMF, we compare the distribution of Halpha-to-FUV flux ratios from ~ 1500 simple, periodic model SFHs with observations of 185 galaxies from the Spitzer Local Volume Legacy survey. We find a set of SFH models that are well matched to the data, such that more massive galaxies are best characterized by nearly constant SFHs, while low mass systems experience bursts amplitudes of ~ 30 (i.e., an increase in the SFR by a factor of 30 over the SFR during the inter-burst period), burst durations of tens of Myr, and periods of ~ 250 Myr; these SFHs are broadly consistent with the increased stochastic star formation expected in systems with lower SFRs. We analyze the predicted temporal evolution of galaxy stellar mass, R-band surface brightness, Halpha-derived SFR, and blue luminosity, and find that they provide a reas...

  1. Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology. II. Dark and stellar mass concentrations for 13 nearby face-on galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Seigar, Marc S. [Department of Physics, University of Minnesota Duluth, 1023 University Drive, MWAH 371, Duluth, MN 55812-3009 (United States); Davis, Benjamin L.; Berrier, Joel; Kennefick, Daniel [Arkansas Center for Space and Planetary Sciences, 202 Field House, University of Arkansas, Fayetteville, AR 72701 (United States)

    2014-11-01

    We investigate the use of spiral arm pitch angles as a probe of disk galaxy mass profiles. We confirm our previous result that spiral arm pitch angles (P) are well correlated with the rate of shear (S) in disk galaxy rotation curves. We use this correlation to argue that imaging data alone can provide a powerful probe of galactic mass distributions out to large look-back times. We then use a sample of 13 galaxies, with Spitzer 3.6 μm imaging data and observed Hα rotation curves, to demonstrate how an inferred shear rate coupled with a bulge-disk decomposition model and a Tully-Fisher-derived velocity normalization can be used to place constraints on a galaxy's baryon fraction and dark matter halo profile. Finally, we show that there appears to be a trend (albeit a weak correlation) between spiral arm pitch angle and halo concentration. We discuss implications for the suggested link between supermassive black hole (SMBH) mass and dark halo concentration, using pitch angle as a proxy for SMBH mass.

  2. Constraining Dark Matter Halo Profiles and Galaxy Formation Models Using Spiral Arm Morphology. II. Dark and Stellar Mass Concentrations for 13 Nearby Face-on Galaxies

    Science.gov (United States)

    Seigar, Marc S.; Davis, Benjamin L.; Berrier, Joel; Kennefick, Daniel

    2014-11-01

    We investigate the use of spiral arm pitch angles as a probe of disk galaxy mass profiles. We confirm our previous result that spiral arm pitch angles (P) are well correlated with the rate of shear (S) in disk galaxy rotation curves. We use this correlation to argue that imaging data alone can provide a powerful probe of galactic mass distributions out to large look-back times. We then use a sample of 13 galaxies, with Spitzer 3.6 μm imaging data and observed Hα rotation curves, to demonstrate how an inferred shear rate coupled with a bulge-disk decomposition model and a Tully-Fisher-derived velocity normalization can be used to place constraints on a galaxy's baryon fraction and dark matter halo profile. Finally, we show that there appears to be a trend (albeit a weak correlation) between spiral arm pitch angle and halo concentration. We discuss implications for the suggested link between supermassive black hole (SMBH) mass and dark halo concentration, using pitch angle as a proxy for SMBH mass.

  3. Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology. II. Dark and stellar mass concentrations for 13 nearby face-on galaxies

    CERN Document Server

    Seigar, Marc S; Berrier, Joel; Kennefick, Daniel

    2014-01-01

    We investigate the use of spiral arm pitch angles as a probe of disk galaxy mass profiles. We confirm our previous result that spiral arm pitch angles (P) are well correlated with the rate of shear (S) in disk galaxy rotation curves. We use this correlation to argue that imaging data alone can provide a powerful probe of galactic mass distributions out to large look-back times. We then use a sample of 13 galaxies, with Spitzer 3.6-$\\mu$m imaging data and observed H$\\alpha$ rotation curves, to demonstrate how an inferred shear rate coupled with a bulge-disk decomposition model and a Tully-Fisher-derived velocity normalization can be used to place constraints on a galaxy's baryon fraction and dark matter halo profile. Finally we show that there appears to be a trend (albeit a weak correlation) between spiral arm pitch angle and halo concentration. We discuss implications for the suggested link between supermassive black hole (SMBH) mass and dark halo concentration, using pitch angle as a proxy for SMBH mass.

  4. Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology. II. Dark and stellar mass concentrations for 13 nearby face-on galaxies

    International Nuclear Information System (INIS)

    We investigate the use of spiral arm pitch angles as a probe of disk galaxy mass profiles. We confirm our previous result that spiral arm pitch angles (P) are well correlated with the rate of shear (S) in disk galaxy rotation curves. We use this correlation to argue that imaging data alone can provide a powerful probe of galactic mass distributions out to large look-back times. We then use a sample of 13 galaxies, with Spitzer 3.6 μm imaging data and observed Hα rotation curves, to demonstrate how an inferred shear rate coupled with a bulge-disk decomposition model and a Tully-Fisher-derived velocity normalization can be used to place constraints on a galaxy's baryon fraction and dark matter halo profile. Finally, we show that there appears to be a trend (albeit a weak correlation) between spiral arm pitch angle and halo concentration. We discuss implications for the suggested link between supermassive black hole (SMBH) mass and dark halo concentration, using pitch angle as a proxy for SMBH mass.

  5. Highlighting XMM-Newton's Role in Time Domain Studies of Neutron Star and Black Hole X-ray binaries in Nearby Galaxies

    Science.gov (United States)

    Laycock, S.; Yang, J.; Cappallo, R.; Christodoulou, D.; Steiner, J.

    2016-09-01

    XMM-Newton's combination of large effective area, superior event timing, and wide field imaging have provided a powerful capability for time-domain studies of nearby X-ray binary populations. In its first 15 years XMM has accomplished groundbreaking monitoring surveys for X-ray binaries; complemented by RXTE, Chandra, and Nustar. Over the next decade XMM's capabilities will complement a new generation of missions including Astrosat, Hitomi, and NICER. This paper highlights the role of XMM-Newton in combination with other missions, in exploring the HMXB populations of the Small Magellanic Cloud and IC 10. Both are nearby dwarf starburst galaxies, yet their ages and evolutionary scenarios are very different, the consequences of which have led to contrasting X-ray binary populations. In the SMC the definitive sample of X-ray binary pulsars assembled by RXTE is revealing fundamental accretion physics when probed by XMM. Finding and characterizing IC 10's youthful X-ray binaries required the combination of XMM together with Chandra and Nustar. Key results include the revelatory finding of an X-ray irradiated wind masking the mass-function in the WR+BH binary X-1 and the measurement of the BH's spin. Such studies have wide relevance to stellar/galactic evolution, implications for black hole masses and formation channels for BH+BH binaries.

  6. A Radio through X-ray Study of the Hot Spots, Active Nucleus, and Environment of the Nearby FR II Radio Galaxy 3C 33

    CERN Document Server

    Kraft, R P; Hardcastle, M J; Evans, D A; Croston, J H; Worrall, D M; Murray, S S

    2007-01-01

    We present results from {\\em Chandra}/ACIS-S, {\\em Spitzer}, {\\em XMM-Newton}, {\\em HST}, and VLA observations of the radio hot spots, extended environment, and nucleus of the nearby ($z$=0.0597) FR II radio galaxy 3C 33. This is a relatively low-power FR II radio galaxy, and so we expect, {\\it a priori}, to detect a significant X-ray synchrotron component to the emission from the hot spots. We detect X-ray emission coincident with the two knots of polarized optical emission from the southern hot spot (SHS), as well as along the northwest arm of this hot spot. We also detect X-ray emission from two compact regions of the northern hot spot (NHS), as well as diffuse emission behind the radio peak. The X-ray flux density of the region at the tip of the southern hot spot, the most compact radio feature of the southern lobe, is consistent with the synchrotron self-Compton (SSC) process. The X-ray flux densities of the other three regions of the SHS and the two compact regions of the NHS are an order of magnitude o...

  7. Finding $\\eta$ Car Analogs in Nearby Galaxies Using Spitzer: II. Identification of An Emerging Class of Extragalactic Self-Obscured Stars

    CERN Document Server

    Khan, Rubab; Stanek, K Z; Gerke, Jill

    2014-01-01

    Understanding the late-stage evolution of the most massive stars such as $\\eta$ Carinae is challenging because no true analogs of $\\eta$ Car have been clearly identified in the Milky Way or other galaxies. In Khan et. al. (2013), we utilized Spitzer IRAC images of $7$ nearby ($\\lesssim4$ Mpc) galaxies to search for such analogs, and found $34$ candidates with flat or red mid-IR spectral energy distributions. Here, in Paper II, we present our characterization of these candidates using multi-wavelength data from the optical through the far-IR. Our search detected no true analogs of $\\eta$ Car, which implies an eruption rate that is a fraction $0.01\\lesssim F \\lesssim 0.19$ of the ccSN rate. This is roughly consistent with each $M_{ZAMS} \\gtrsim 70M_\\odot$ star undergoing $1$ or $2$ outbursts in its lifetime. However, we do identify a significant population of $18$ lower luminosity $\\left(\\log(L/L_\\odot)\\simeq5.5-6.0\\right)$ dusty stars. Stars enter this phase at a rate that is fraction $0.09 \\lesssim F \\lesssim...

  8. The Asymptotic Giant Branch and the Tip of the Red Giant Branch as Probes of Star Formation History: The Nearby Dwarf Irregular Galaxy KKH 98

    CERN Document Server

    Melbourne, J; Dalcanton, J; Ammons, S M; Max, C; Koo, D C; Girardi, Leo; Dolphin, A

    2010-01-01

    We investigate the utility of the asymptotic giant branch (AGB) and the red giant branch (RGB) as probes of the star formation history (SFH) of the nearby (D=2.5 Mpc) dwarf irregular galaxy, KKH 98. Near-infrared (IR) Keck Laser Guide Star Adaptive Optics (AO) images resolve 592 IR bright stars reaching over 1 magnitude below the Tip of the Red Giant Branch. Significantly deeper optical (F475W and F814W) Hubble Space Telescope images of the same field contain over 2500 stars, reaching to the Red Clump and the Main Sequence turn-off for 0.5 Gyr old populations. Compared to the optical color magnitude diagram (CMD), the near-IR CMD shows significantly tighter AGB sequences, providing a good probe of the intermediate age (0.5 - 5 Gyr) populations. We match observed CMDs with stellar evolution models to recover the SFH of KKH 98. On average, the galaxy has experienced relatively constant low-level star formation (5 x 10^-4 Mo yr^-1) for much of cosmic time. Except for the youngest main sequence populations (age &...

  9. PTF11eon/SN2011dh: Discovery of a Type IIb Supernova From a Compact Progenitor in the Nearby Galaxy M51

    CERN Document Server

    Arcavi, Iair; Yaron, Ofer; Sternberg, Assaf; Rabinak, Itay; Waxman, Eli; Kasliwal, Mansi M; Quimby, Robert M; Ofek, Eran O; Horesh, Assaf; Kulkarni, Shrinivas R; Filippenko, Alexei V; Silverman, Jeffrey M; Cenko, S Bradley; Li, Weidong; Bloom, Joshua S; Sullivan, Mark; Fox, Derek B; Nugent, Peter E; Poznanski, Dovi; Gorbikov, Evgeny; Riou, Amedee; Lamotte-Bailey, Stephane; Griga, Thomas; Cohen, Judith G; Polishook, David; Xu, Dong; Ben-Ami, Sagi; Manulis, Ilan; Walker, Emma S; Mazzali, Paulo A; Pian, Elena; Matheson, Thomas; Maquire, Kate; Pan, Yen-Chen; Bersier, David; James, Philip; Marchant, Jonathan M; Smith, Robert J; Mottram, Chris J; Barnsley, Robert M; Kandrashoff, Michael T; Clubb, Kelsey I

    2011-01-01

    On May 31, 2011 UT a supernova (SN) exploded in the nearby galaxy M51 (the Whirlpool Galaxy). We discovered this event using small telescopes equipped with CCD cameras, as well as by the Palomar Transient Factory (PTF) survey, and rapidly confirmed it to be a Type II supernova. Our early light curve and spectroscopy indicates that PTF11eon resulted from the explosion of a relatively compact progenitor star as evidenced by the rapid shock-breakout cooling seen in the light curve, the relatively low temperature in early-time spectra and the prompt appearance of low-ionization spectral features. The spectra of PTF11eon are dominated by H lines out to day 10 after explosion, but initial signs of He appear to be present. Assuming that He lines continue to develop in the near future, this SN is likely a member of the cIIb (compact IIb; Chevalier and Soderberg 2010) class, with progenitor radius larger than that of SN 2008ax and smaller than the eIIb (extended IIb) SN 1993J progenitor. Our data imply that the object...

  10. UV-bright nearby early type galaxies observed in the mid-infrared: evidence for a multi-stage formation history by way of WISE and GALEX imaging

    CERN Document Server

    Petty, S M; Jarrett, T H; Blain, A W; Farrah, D G; Rich, R M; Tsai, C -W; Benford, D J; Bridge, C R; Lake, S E; Masci, F J; Wright, E L

    2013-01-01

    In the local Universe, 10% of massive elliptical galaxies are observed to exhibit a peculiar property: a substantial excess of ultraviolet emission (UVX) over what is expected from their old, red stellar populations. Several origins for the UVX have been proposed, including a population of hot young stars, or a population of old, blue horizontal branch or extended horizontal branch (BHB or EHB) stars that have undergone substantial mass loss from their outer atmospheres. We explore the radial distribution of ultraviolet excess (UVX) in a selection of 49 nearby E/S0-type galaxies by measuring the extended photometry in the UV-midIR with GALEX, SDSS and WISE. We compare UV/optical and UV/mid-IR colors with the Flexible Stellar Population Synthesis with EHB models (Conroy & Gunn 2010). We find that combined WISE mid-IR and GALEX UV colors are more effective in distinguishing models than optical colors, and that the UV/mid-IR combination is sensitive to EHB fraction. There are strong color gradients with the ...

  11. A radio jet drives a molecular & atomic gas outflow in multiple regions within one square kiloparsec of the nucleus of the nearby galaxy IC5063

    CERN Document Server

    Dasyra, K M; Combes, F; Vlahakis, N

    2015-01-01

    We analyzed near-infrared data of the nearby galaxy IC5063 taken with the Very Large Telescope SINFONI instrument. IC5063 is an elliptical galaxy that has a radio jet nearly aligned with the major axis of a gas disk in its center. The data reveal multiple signatures of molecular and atomic gas that has been kinematically distorted by the jet passage within an area of ~1 kpc^2. Concrete evidence that the impact of jet plasma upon gas causes the gas to accelerate comes from outflows detected near four different bending points of the jet: at the two bright radio lobes, near a diverted plasma stream close to the north lobe, and near the tip of a plasma stream in the narrow-line region. Gas moving with a velocity excess of 600 km/s to 1200 km/s with respect to ordered motions is detected in [FeII], Paa, and H2 lines. Around these regions, gas is scattered in different directions. Near the north lobe, the highly blueshifted and the highly redshifted [FeII] emission is offset by 240 pc. The (scattered or not) plasma...

  12. The Thirteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey MApping Nearby Galaxies at Apache Point Observatory

    CERN Document Server

    Albareti, Franco D; Almeida, Andres; Anders, Friedrich; Anderson, Scott; Andrews, Brett H; Aragon-Salamanca, Alfonso; Argudo-Fernandez, Maria; Armengaud, Eric; Aubourg, Eric; Avila-Reese, Vladimir; Badenes, Carles; Bailey, Stephen; Barbuy, Beatriz; Barger, Kat; Barrera-Ballesteros, Jorge; Bartosz, Curtis; Basu, Sarbani; Bates, Dominic; Battaglia, Giuseppina; Baumgarten, Falk; Baur, Julien; Bautista, Julian; Beers, Timothy C; Belfiore, Francesco; Bershady, Matthew; de Lis, Sara Bertran; Bird, Jonathan C; Bizyaev, Dmitry; Blanc, Guillermo A; Blanton, Michael; Blomqvist, Michael; Bolton, Adam S; Borissova, J; Bovy, Jo; Brandt, William Nielsen; Brinkmann, Jonathan; Brownstein, Joel R; Bundy, Kevin; Burtin, Etienne; Busca, Nicolas G; Chavez, Hugo Orlando Camacho; Diaz, M Cano; Cappellari, Michele; Carrera, Ricardo; Chen, Yanping; Cherinka, Brian; Cheung, Edmond; Chiappini, Cristina; Chojnowski, Drew; Chuang, Chia-Hsun; Chung, Haeun; Cirolini, Rafael Fernando; Clerc, Nicolas; Cohen, Roger E; Comerford, Julia M; Comparat, Johan; Cousinou, Marie-Claude; Covey, Kevin; Crane, Jeffrey D; Croft, Rupert; Cunha, Katia; da Costa, Luiz; Ilha, Gabriele da Silva; Darling, Jeremy; Davidson, James W; Dawson, Kyle; De Lee, Nathan; de la Macorra, Axel; de la Torre, Sylvain; Machado, Alice Deconto; Delubac, Timothee; Diamond-Stanic, Aleksandar M; Donor, John; Downes, Juan Jose; Drory, Niv; Bourboux, Helion du Mas des; Du, Cheng; Dwelly, Tom; Ebelke, Garrett; Eigenbrot, Arthur; Eisenstein, Daniel J; Elsworth, Yvonne P; Emsellem, Eric; Eracleous, Michael; Escoffier, Stephanie; Evans, Michael L; Falcon-Barroso, Jesus; Fan, Xiaohui; Favole, Ginevra; Fernandez-Alvar, Emma; Fernandez-Trincado, J G; Feuillet, Diane; Fleming, Scott W; Font-Ribera, Andreu; Freischlad, Gordon; Frinchaboy, Peter; Fu, Hai; Gao, Yang; Garcia-Hernandez, D A; Perez, Ana E Garcia; Garcia, Rafael A; Garcia-Dias, R; Gaulme, Patrick; Ge, Junqiang; Geisler, Douglas; Marin, Hector Gil; Gillespie, Bruce; Girardi, Leo; Goddard, Daniel; Chew, Yilen Gomez Maqueo; Gonzalez-Perez, Violeta; Grabowski, Kathleen; Green, Paul; Grier, Catherine J; Grier, Thomas; Guo, Hong; Guy, Julien; Hagen, Alex; Hall, Matt; Harding, Paul; Harley, R E; Hasselquist, Sten; Hawley, Suzanne; Hayes, Christian R; Hearty, Fred; Hekker, Saskia; Toledo, Hector Hernandez; Ho, Shirley; Hogg, David W; Holley-Bockelmann, Kelly; Holtzman, Jon A; Holzer, Parker H; Hu, Jian; Huber, Daniel; Hutchinson, Timothy Alan; Hwang, Ho Seong; Ibarra-Medel, Hector J; Ivans, Inese I; Ivory, KeShawn; Jaehnig, Kurt; Jensen, Trey W; Johnson, Jennifer A; Jones, Amy; Jullo, Eric; Kallinger, T; Kinemuchi, Karen; Kirkby, David; Klaene, Mark; Kneib, Jean-Paul; Kollmeier, Juna A; Lacerna, Ivan; Lane, Richard R; Lang, Dustin; Laurent, Pierre; Law, David R; Goff, Jean-Marc Le; Leauthaud, Alexie; Li, Cheng; Li, Ran; Li, Chen; Li, Niu; Liang, Fu-Heng; Liang, Yu; Lima, Marcos; Lin, Lihwai; Lin, Lin; Lin, Yen-Ting; Long, Dan; Lucatello, Sara; MacDonald, Nicholas; MacLeod, Chelsea L; Mackereth, J Ted; Mahadevan, Suvrath; Maia, Marcio Antonio-Geimba; Maiolino, Roberto; Majewski, Steven R; Malanushenko, Olena; Mallmann, Nicolas Dullius; Manchado, Arturo; Maraston, Claudia; Marques-Chaves, Rui; Valpuesta, Inma Martinez; Masters, Karen L; Mathur, Savita; McGreer, Ian D; Merloni, Andrea; Merrifield, Michael R; Meszaros, Szabolcs; Meza, Andres; Miglio, Andrea; Minchev, Ivan; Molaverdikhani, Karan; Montero-Dorta, Antonio D; Mosser, Benoit; Muna, Demitri; Myers, Adam; Nair, Preethi; Nandra, Kirpal; Ness, Melissa; Newman, Jeffrey A; Nichol, Robert C; Nidever, David L; Nitschelm, Christian; O'Connell, Julia; Oravetz, Audrey; Padilla, Nelson; Palanque-Delabrouille, Nathalie; Pan, Kaike; Parejko, John; Paris, Isabelle; Peacock, John A; Peirani, Sebastien; Pellejero-Ibanez, Marcos; Penny, Samantha; Percival, Will J; Percival, Jeffrey W; Perez-Fournon, Ismael; Petitjean, Patrick; Pieri, Matthew; Pinsonneault, Marc H; Pisani, Alice; Prada, Francisco; Prakash, Abhishek; Price-Jones, Natalie; Raddick, M Jordan; Rahman, Mubdi; Raichoor, Anand; Rembold, Sandro Barboza; Reyna, A M; Rich, James; Richstein, Hannah; Ridl, Jethro; Riffel, Rogerio; Riffel, Rogemar A; Rix, Hans-Walter; Robin, Annie C; Rockosi, Constance M; Rodriguez-Torres, Sergio; Rodrigues, Thaise S; Roe, Natalie; Lopes, A Roman; Roman-Zuniga, Carlos; Ross, Ashley J; Rossi, Graziano; Ruan, John; Ruggeri, Rossana; Runnoe, Jessie C; Salazar-Albornoz, Salvador; Salvato, Mara; Sanchez, Ariel G; Sanchez, Sebastian F; Sanchez-Gallego, Jose R; Santiago, Basilio Xavier; Schiavon, Ricardo; Schimoia, Jaderson S; Schlafly, Eddie; Schlegel, David J; Schneider, Donald P; Schoenrich, Ralph; Schultheis, Mathias; Schwope, Axel; Seo, Hee-Jong; Serenelli, Aldo; Sesar, Branimir; Shao, Zhengyi; Shetrone, Matthew; Shull, Michael; Aguirre, Victor Silva; Skrutskie, M F; Slosar, Anže; Smith, Michael; Smith, Verne V; Sobeck, Jennifer; Somers, Garrett; Souto, Diogo; Stark, David V; Stassun, Keivan G; Steinmetz, Matthias; Stello, Dennis; Bergmann, Thaisa Storchi; Strauss, Michael A; Streblyanska, Alina; Stringfellow, Guy S; Suarez, Genaro; Sun, Jing; Taghizadeh-Popp, Manuchehr; Tang, Baitian; Tao, Charling; Tayar, Jamie; Tembe, Mita; Thomas, Daniel; Tinker, Jeremy; Tojeiro, Rita; Tremonti, Christy; Troup, Nicholas; Trump, Jonathan R; Unda-Sanzana, Eduardo; Valenzuela, O; Bosch, Remco van den; Vargas-Magana, Mariana; Vazquez, Jose Alberto; Villanova, Sandro; Vivek, M; Vogt, Nicole; Wake, David; Walterbos, Rene; Wang, Yuting; Wang, Enci; Weaver, Benjamin Alan; Weijmans, Anne-Marie; Weinberg, David H; Westfall, Kyle B; Whelan, David G; Wilcots, Eric; Wild, Vivienne; Williams, Rob A; Wilson, John; Wood-Vasey, W M; Wylezalek, Dominika; Xiao, Ting; Yan, Renbin; Yang, Meng; Ybarra, Jason E; Yeche, Christophe; Yuan, Fang-Ting; Zakamska, Nadia; Zamora, Olga; Zasowski, Gail; Zhang, Kai; Zhao, Cheng; Zhao, Gong-Bo; Zheng, Zheng; Zheng, Zheng; Zhou, Zhi-Min; Zhu, Guangtun; Zinn, Joel C; Zou, Hu

    2016-01-01

    The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2, MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA, the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions of the SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1 data from SDSS-III, with abundances o...

  13. Deep Chandra X-ray Imaging of a Nearby Radio Galaxy 4C+29.30: X-ray/Radio Connection

    CERN Document Server

    Siemiginowska, Aneta; Cheung, Chi C; Aldcroft, Thomas L; Bechtold, Jill; Burke, D J; Evans, Daniel; Holt, Joanna; Jamrozy, Marek; Migliori, Giulia; .,

    2012-01-01

    We report results from our deep Chandra X-ray observations of a nearby radio galaxy, 4C+29.30 (z=0.0647). The Chandra image resolves structures on sub-arcsec to arcsec scales, revealing complex X-ray morphology and detecting the main radio features: the nucleus, a jet, hotspots, and lobes. The nucleus is absorbed (N(H)=3.95 (+0.27/-0.33)x10^23 atoms/cm^2) with an unabsorbed luminosity of L(2-10 keV) ~ (5.08 +/-0.52) 10^43 erg/s characteristic of Type 2 AGN. Regions of soft (<2 keV) X-ray emission that trace the hot interstellar medium (ISM) are correlated with radio structures along the main radio axis indicating a strong relation between the two. The X-ray emission beyond the radio source correlates with the morphology of optical line-emitting regions. We measured the ISM temperature in several regions across the galaxy to be kT ~ 0.5 with slightly higher temperatures (of a few keV) in the center and in the vicinity of the radio hotspots. Assuming these regions were heated by weak shocks driven by the exp...

  14. Integrated Spectroscopy of the Herschel Reference Survey. The spectral line properties of a volume-limited, K-band selected sample of nearby galaxies

    CERN Document Server

    Boselli, A; Cortese, L; Gavazzi, G; Buat, V

    2012-01-01

    We present long-slit integrated spectroscopy of 238 late-type galaxies belonging to the Herschel Reference Survey, a volume limited sample representative of the nearby universe. This sample has a unique legacy value since ideally defined for any statistical study of the multifrequency properties of galaxies spanning a large range in morphological type and luminosity. The spectroscopic observations cover the spectral range 3600-6900 A at a resolution R ~ 1000 and are thus suitable for separating the underlying absorption from the emission of the Hbeta line as well as the two [NII] lines from the Halpha emission. We measure the fluxes and the equivalent widths of the strongest emission lines ([OII], Hbeta, [OIII], [NII], Halpha, and [SII]). The data are used to study the distribution of the equivalent width of all the emission lines, of the Balmer decrement C(Hbeta) and of the observed underlying Balmer absorption under Hbeta in this sample. Combining these new spectroscopic data with those available at other f...

  15. The BaLROG project - II. Quantifying the influence of bars on the stellar populations of nearby galaxies

    Science.gov (United States)

    Seidel, M. K.; Falcón-Barroso, J.; Martínez-Valpuesta, I.; Sánchez-Blázquez, P.; Pérez, I.; Peletier, R.; Vazdekis, A.

    2016-08-01

    We continue the exploration of the BaLROG (Bars in Low Redshift Optical Galaxies) sample: 16 large mosaics of barred galaxies observed with the integral field unit Spectrographic Areal Unit for Research on Optical Nebulae. We quantify the influence of bars on the composition of the stellar component. We derive line-strength indices of H β, Fe5015 and Mgb. Based on single stellar population (SSP) models, we calculate ages, metallicities and [Mg/Fe] abundances and their gradients along the bar major and minor axes. The high spatial resolution of our data allows us to identify breaks among index and SSP profiles, commonly at 0.13 ± 0.06 bar length, consistent with kinematic features. Inner gradients are about 10 times steeper than outer gradients and become larger when there is a central rotating component, implying that the gradients are not independent of dynamics and orbits. Central ages appear to be younger for stronger bars. Yet, the bar regions are usually old. We find a flattening of the iron (Fe5015) and magnesium (Mgb) outer gradients along the bar major axis, translating into a flattening of the metallicity gradient. This gradient is found to be 0.03 ± 0.07 dex kpc-1 along the bar major axis while the mean value of the bar minor axis compares well with that of an unbarred control sample and is significantly steeper, namely -0.20 ± 0.04 dex kpc-1. These results confirm recent simulations and discern the important localized influence of bars. The elevated [Mg/Fe] abundances of bars and bulges compared to the lower values of discs suggest an early formation, in particular for early-type galaxies.

  16. CARMA SURVEY TOWARD INFRARED-BRIGHT NEARBY GALAXIES (STING). II. MOLECULAR GAS STAR FORMATION LAW AND DEPLETION TIME ACROSS THE BLUE SEQUENCE

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Nurur; Bolatto, Alberto D.; Fisher, David B.; Vogel, Stuart N. [Department of Astronomy, University of Maryland, College Park, MD (United States); Xue Rui; Wong, Tony [Department of Astronomy, University of Illinois, Urbana-Champaign, IL (United States); Leroy, Adam K. [National Radio Astronomy Observatory, Charlottesville, VA (United States); Walter, Fabian [Max-Planck-Institute fur Astronomie, Heidelberg (Germany); Bigiel, Frank [Institut fuer Theoretische Astrophysik, Universitaet Heidelberg, D-69120 Heidelberg (Germany); Rosolowsky, Erik [I. K. Barber School of the Arts and Science, University of British-Columbia, Kelowna, BC (Canada); Blitz, Leo [Department of Astronomy, University of California, Berkeley, CA (United States); West, Andrew A. [Department of Astronomy, Boston University, Boston, MA (United States); Ott, Juergen, E-mail: nurur@astro.umd.edu [National Radio Astronomy Observatory, Socorro, NM (United States)

    2012-02-01

    We present an analysis of the relationship between molecular gas and current star formation rate surface density at sub-kiloparsec and kiloparsec scales in a sample of 14 nearby star-forming galaxies. Measuring the relationship in the bright, high molecular gas surface density ({Sigma}{sub H{sub 2}}{approx}>20 M{sub Sun} pc{sup -2}) regions of the disks to minimize the contribution from diffuse extended emission, we find an approximately linear relation between molecular gas and star formation rate surface density, N{sub mol} {approx} 0.96 {+-} 0.16, with a molecular gas depletion time, {tau}{sup mol}{sub dep} {approx} 2.30 {+-} 1.32 Gyr. We show that in the molecular regions of our galaxies there are no clear correlations between {tau}{sup mol}{sub dep} and the free-fall and effective Jeans dynamical times throughout the sample. We do not find strong trends in the power-law index of the spatially resolved molecular gas star formation law or the molecular gas depletion time across the range of galactic stellar masses sampled (M{sub *} {approx} 10{sup 9.7}-10{sup 11.5} M{sub Sun }). There is a trend, however, in global measurements that is particularly marked for low-mass galaxies. We suggest that this trend is probably due to the low surface brightness CO J = 1-0, and it is likely associated with changes in CO-to-H{sub 2} conversion factor.

  17. The Ionized Gas in Nearby Galaxies as Traced by the [N II] 122 and 205 μm Transitions

    OpenAIRE

    Herrera-Camus, R.; Bolatto, A.; Smith, J. D.; Draine, B.; Pellegrini, E.; Wolfire, M.; Croxall, K.; De Looze, I.; Calzetti, D.; Kennicutt, R.; Crocker, A.; Armus, L.; van der Werf, P.; Sandstrom, K.; Galametz, M.

    2016-01-01

    The [N ii] 122 and 205 μm transitions are powerful tracers of the ionized gas in the interstellar medium. By combining data from 21 galaxies selected from the Herschel KINGFISH and Beyond the Peak surveys, we have compiled 141 spatially resolved regions with a typical size of ~1 kpc, with observations of both [N ii] far-infrared lines. We measure [N ii] 122/205 line ratios in the ~0.6–6 range, which corresponds to electron gas densities of n_e ~ 1–300 cm^(−3), with a median value of n_e = 30 ...

  18. Faint Dwarfs in Nearby Groups

    CERN Document Server

    Speller, Ryan

    2013-01-01

    The number and distribution of dwarf satellite galaxies remain a critical test of cold dark matter-dominated structure formation on small scales. Until recently, observational information about galaxy formation on these scales has been limited mainly to the Local Group. We have searched for faint analogues of Local Group dwarfs around nearby bright galaxies, using a spatial clustering analysis of the photometric catalog of the Sloan Digital Sky Survey (SDSS) Data Release 8. Several other recent searches of SDSS have detected clustered satellite populations down to $\\Delta m_r \\equiv ({m}_{r,\\, {\\rm sat}} -\\, {m}_{r,\\, {\\rm main}}) \\sim 6$-$8$, using photometric redshifts to reduce background contamination. SDSS photometric redshifts are relatively imprecise, however, for faint and nearby galaxies. Instead we use angular size to select potential nearby dwarfs, and consider only the nearest isolated bright galaxies as primaries. As a result, we are able to detect an excess clustering signal from companions down...

  19. Constraints on neutrino masses from the study of the nearby large-scale structure and galaxy cluster counts

    CERN Document Server

    Boehringer, Hans

    2016-01-01

    The high precision measurements of the cosmic microwave background by the Planck survey yielded tight constraints on cosmological parameters and the statistics of the density fluctuations at the time of recombination. This provides the means for a critical study of structure formation in the Universe by comparing the microwave background results with present epoch measurements of the cosmic large-scale structure. It can reveal subtle effects such as how different forms of Dark Matter may modify structure growth. Currently most interesting is the damping effect of structure growth by massive neutrinos. Different observations of low redshift matter density fluctuations provided evidence for a signature of massive neutrinos. Here we discuss the study of the cosmic large-scale structure with a complete sample of nearby, X-ray luminous clusters from our REFLEX cluster survey. From the observed X-ray luminosity function and its reproduction for different cosmological models, we obtain tight constraints on the cosmo...

  20. ALFALFA Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo P. IV. Distance Measurement from LBT Optical Imaging

    CERN Document Server

    McQuinn, Kristen B W; Berg, Danielle; Cannon, John M; Salzer, John J; Adams, Elizabeth A K; Dolphin, Andrew; Giovanelli, Riccardo; Haynes, Martha P; Rhode, Katherine L

    2013-01-01

    Leo P is a low-luminosity dwarf galaxy discovered through the blind HI Arecibo Legacy Fast ALFA (ALFALFA) survey. The HI and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with both active star formation and an underlying older population, as well as an extremely low oxygen abundance. Here, we measure the distance to Leo P by applying the tip of the red giant branch (TRGB) distance method to photometry of the resolved stellar population from new Large Binocular Telescope (LBT) V and I band imaging. We measure a distance modulus of 26.19 (+0.17/-0.50) mag corresponding to a distance of 1.72 (+0.14/-0.40) Mpc. Although our photometry reaches 3 magnitudes below the TRGB, the sparseness of the red giant branch (RGB) yields higher uncertainties on the lower limit of the distance. Leo P is outside the Local Group with a distance and velocity consistent with the local Hubble flow. While located in a very low-density environment, Leo P lies within ~0.5 Mpc of a loose association of dw...

  1. The VIRUS-P Exploration of Nearby Galaxies (VENGA): Radial Gas Inflow and Shock Excitation in NGC 1042

    CERN Document Server

    Luo, Rongxin; Blanc, Guillermo A; Jogee, Shardha; Bosch, Remco C E van den; Weinzirl, Tim

    2016-01-01

    NGC 1042 is a late type bulgeless disk galaxy which hosts a low luminosity Active Galactic Nuclei (AGN) coincident with a massive nuclear star cluster. In this paper, we present the integral-field-spectroscopy (IFS) studies of this galaxy, based on the data obtained with the Mitchell spectrograph on the 2.7 meter Harlan J. Smith telescope. In the central $100\\textrm{-}300\\ \\mathrm{pc}$ region of NGC 1042, we find a circumnuclear ring structure of gas with enhanced ionization, which we suggest is mainly induced by shocks. Combining with the harmonic decomposition analysis of the velocity field of the ionized gas, we propose that the shocked gas is the result of gas inflow driven by the inner spiral arms. The inflow velocity is $\\sim 32\\pm10\\ \\mathrm{km}\\ \\mathrm{s}^{-1}$ and the estimated mass inflow rate is $\\sim 1.1\\pm0.3 \\times 10^{-3}\\ \\mathrm{M}_{\\odot}\\ \\mathrm{yr}^{-1}$. The mass inflow rate is about one hundred times the blackhole's mass accretion rate ($\\sim 1.4 \\times 10^{-5}\\ \\mathrm{M}_{\\odot}\\ \\ma...

  2. The Ionized Gas in Nearby Galaxies as Traced by the [NII] 122 and 205 \\mu m Transitions

    CERN Document Server

    Herrera-Camus, R; Smith, J D; Draine, B; Pellegrini, E; Wolfire, M; Croxall, K; de Looze, I; Calzetti, D; Kennicutt, R; Crocker, A; Armus, L; van der Werf, P; Sandstrom, K; Galametz, M; Brandl, B; Groves, B; Rigopoulou, D; Walter, F; Leroy, A; Boquien, M; Tabatabaei, F S; Beirao, P

    2016-01-01

    The [NII] 122 and 205 \\mu m transitions are powerful tracers of the ionized gas in the interstellar medium. By combining data from 21 galaxies selected from the Herschel KINGFISH and Beyond the Peak surveys, we have compiled 141 spatially resolved regions with a typical size of ~1 kiloparsec, with observations of both [NII] far-infrared lines. We measure [NII] 122/205 line ratios in the ~0.6-6 range, which corresponds to electron gas densities $n_e$~1-300 cm$^{-3}$, with a median value of $n_e$=30 cm$^{-3}$. Variations in the electron density within individual galaxies can be as a high as a factor of ~50, frequently with strong radial gradients. We find that $n_e$ increases as a function of infrared color, dust-weighted mean starlight intensity, and star formation rate surface density ($\\Sigma_{SFR}$). As the intensity of the [NII] transitions is related to the ionizing photon flux, we investigate their reliability as tracers of the star formation rate (SFR). We derive relations between the [NII] emission and...

  3. The nature of the low-frequency emission of M51: First observations of a nearby galaxy with LOFAR

    CERN Document Server

    Mulcahy, D D; Beck, R; Heald, G; Fletcher, A; Scaife, A; Adebahr, B; Anderson, J M; Bonafede, A; Brüggen, M; Brunetti, G; Chyży, K T; Conway, J; Dettmar, R-J; Enßlin, T; Haverkorn, M; Horellou, C; Iacobelli, M; Israel, F P; Junklewitz, H; Jurusik, W; Köhler, J; Kuniyoshi, M; Orrú, E; Paladino, R; Pizzo, R; Reich, W; Röttgering, H J A

    2014-01-01

    The grand-design spiral galaxy M51 was observed with the LOFAR High Frequency Antennas (HBA) and imaged in total intensity and polarisation. This observation covered the frequencies between 115 MHz and 175 MHz. We produced an image of total emission of M51 at the mean frequency of 151 MHz with 20 arcsec resolution and 0.3 mJy rms noise, which is the most sensitive image of a galaxy at frequencies below 300 MHz so far. The integrated spectrum of total radio emission is described well by a power law, while flat spectral indices in the central region indicate thermal absorption. We observe that the disk extends out to 16 kpc and see a break in the radial profile near the optical radius of the disk. Our main results, the scale lengths of the inner and outer disks at 151 MHz and 1.4 GHz, arm--interarm contrast, and the break scales of the radio--far-infrared correlations, can be explained consistently by CRE diffusion, leading to a longer propagation length of CRE of lower energy. The distribution of CRE sources d...

  4. ALFALFA Discovery of the Nearby Gas-rich Dwarf Galaxy Leo P. V. Neutral Gas Dynamics and Kinematics

    CERN Document Server

    Bernstein-Cooper, Elijah Z; Elson, Edward C; Warren, Steven R; Chengalur, Jayaram; Skillman, Evan D; Adams, Elizabeth A K; Bolatto, Alberto D; Giovanelli, Riccardo; Haynes, Martha P; McQuinn, Kristen B W; Pardy, Stephen A; Rhode, Katherine L; Salzer, John J

    2014-01-01

    We present new HI spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our HI images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The HI morphology is slightly elongated along the optical major-axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V_c = 15 +/- 5 km/s. Within the HI radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ~15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature ...

  5. The BaLROG project - II. Quantifying the influence of bars on the stellar populations of nearby galaxies

    CERN Document Server

    Seidel, Marja K; Martínez-Valpuesta, Inma; Sánchez-Blázquez, Patricia; Pérez, Isabel; Peletier, Reynier; Vazdekis, Alexandre

    2016-01-01

    We continue the exploration of the BaLROG (Bars in Low Redshift Optical Galaxies) sample: 16 large mosaics of barred galaxies observed with the integral field unit SAURON. We quantify the influence of bars on the composition of the stellar component. We derive linestrength indices of H${\\beta}$, Fe5015 and Mgb. Based on single stellar population (SSP) models, we calculate ages, metallicities and [Mg/Fe] abundances and their gradients along the bar major and minor axes. The high spatial resolution of our data allows us to identify breaks among index and SSP profiles, commonly at 0.13$\\pm$0.06 bar length, consistent with kinematic features. Inner gradients are about ten times steeper than outer gradients and become larger when there is a central rotating component, implying that the gradients are not independent of dynamics and orbits. Central ages appear to be younger for stronger bars. Yet, the bar regions are usually old. We find a flattening of the iron (Fe5015) and magnesium (Mgb) outer gradients along the...

  6. NGC4370: a case study for testing our ability to infer dust distribution and mass in nearby galaxies

    CERN Document Server

    Viaene, S; Baes, M; Fritz, J; Bendo, G J; Boquien, M; Boselli, A; Bianchi, S; Cortese, L; Côté, P; Cuillandre, J -C; De Looze, I; Alighieri, S di Serego; Ferrarese, L; Gwyn, S D J; Hughes, T M; Pappalardo, C

    2015-01-01

    A fraction of the early-type galaxy population hosts a prominent dust lane. Methods to quantify the dust content of these systems based on optical imaging data usually yield dust masses which are an order of magnitude lower than dust masses derived from the observed FIR emission. High-quality optical data from the Next Generation Virgo cluster Survey (NGVS) and FIR/submm observations from the Herschel Virgo Cluster Survey (HeViCS) allow us to revisit previous methods to determine the dust content in galaxies and explore new ones. We aim to derive the dust mass in NGC 4370 from both optical and FIR data, and investigate the need to invoke a putative diffuse dust component. We create color and attenuation maps, which are converted to approximate dust mass maps based on simple dust geometries. Dust masses are also derived from SED fits to FIR/submm observations. Finally, inverse radiative transfer fitting is performed to investigate more complex dust geometries. The empirical methods applied to the optical data ...

  7. Constraints on neutrino masses from the study of the nearby large-scale structure and galaxy cluster counts

    Science.gov (United States)

    Böhringer, Hans; Chon, Gayoung

    2016-07-01

    The high precision measurements of the cosmic microwave background by the Planck survey yielded tight constraints on cosmological parameters and the statistics of the density fluctuations at the time of recombination. This provides the means for a critical study of structure formation in the Universe by comparing the microwave background results with present epoch measurements of the cosmic large-scale structure. It can reveal subtle effects such as how different forms of Dark Matter may modify structure growth. Currently most interesting is the damping effect of structure growth by massive neutrinos. Different observations of low redshift matter density fluctuations provided evidence for a signature of massive neutrinos. Here we discuss the study of the cosmic large-scale structure with a complete sample of nearby, X-ray luminous clusters from our REFLEX cluster survey. From the observed X-ray luminosity function and its reproduction for different cosmological models, we obtain tight constraints on the cosmological parameters describing the matter density, Ωm, and the density fluctuation amplitude, σ8. A comparison of these constraints with the Planck results shows a discrepancy in the framework of a pure ΛCDM model, but the results can be reconciled, if we allow for a neutrino mass in the range of 0.17 eV to 0.7 eV. Also some others, but not all of the observations of the nearby large-scale structure provide evidence or trends for signatures of massive neutrinos. With further improvement in the systematics and future survey projects, these indications will develop into a definitive measurement of neutrino masses.

  8. Alfalfa discovery of the nearby gas-rich dwarf galaxy LEO P. V. Neutral gas dynamics and kinematics

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein-Cooper, Elijah Z.; Pardy, Stephen A. [Department of Astronomy, University of Wisconsin, 475 N Charter Street, Madison, WI 53706 (United States); Cannon, John M., E-mail: ezbc@astro.wisc.edu, E-mail: spardy@astro.wisc.edu, E-mail: jcannon@macalester.edu [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); and others

    2014-08-01

    We present new H I spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H I images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H I morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V {sub c} =15 ± 5 km s{sup –1}. Within the H I radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ≳15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s{sup –1} and 10.1 ± 1.2 km s{sup –1}, corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H I component is unresolved at a physical resolution of 200 pc. The highest H I surface densities are observed in close physical proximity to the single H II region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

  9. The nature of the low-frequency emission of M 51. First observations of a nearby galaxy with LOFAR

    Science.gov (United States)

    Mulcahy, D. D.; Horneffer, A.; Beck, R.; Heald, G.; Fletcher, A.; Scaife, A.; Adebahr, B.; Anderson, J. M.; Bonafede, A.; Brüggen, M.; Brunetti, G.; Chyży, K. T.; Conway, J.; Dettmar, R.-J.; Enßlin, T.; Haverkorn, M.; Horellou, C.; Iacobelli, M.; Israel, F. P.; Junklewitz, H.; Jurusik, W.; Köhler, J.; Kuniyoshi, M.; Orrú, E.; Paladino, R.; Pizzo, R.; Reich, W.; Röttgering, H. J. A.

    2014-08-01

    Context. Low-frequency radio continuum observations (challenges of low-frequency radio interferometry. This is now changing with the start of operations of LOFAR. Aims: We aim to study the propagation of low-energy CRE in the interarm regions and the extended disk of the nearly face-on spiral galaxy Messier 51. We also search for polarisation in M 51 and other extragalactic sources in the field. Methods: The grand-design spiral galaxy M 51 was observed with the LOFAR High Frequency Antennas (HBA) and imaged in total intensity and polarisation. This observation covered the frequencies between 115 MHz and 175 MHz with 244 subbands of 8 channels each, resulting in 1952 channels. This allowed us to use RM synthesis to search for polarisation. Results: We produced an image of total emission of M 51 at the mean frequency of 151 MHz with 20'' resolution and 0.3 mJy rms noise, which is the most sensitive image of a galaxy at frequencies below 300 MHz so far. The integrated spectrum of total radio emission is described well by a power law, while flat spectral indices in the central region indicate thermal absorption. We observe that the disk extends out to 16 kpc and see a break in the radial profile near the optical radius of the disk. The radial scale lengths in the inner and outer disks are greater at 151 MHz, and the break is smoother at 151 MHz than those observed at 1.4 GHz. The arm-interarm contrast is lower at 151 MHz than at 1400 MHz, indicating propagation of CRE from spiral arms into interarm regions. The correlations between the images of radio emission at 151 MHz and 1400 MHz and the FIR emission at 70 μm reveal breaks on scales of 1.4 and 0.7 kpc, respectively. The total (equipartition) magnetic field strength decreases from about 28 μG in the central region to about 10 μG at 10 kpc radius. No significant polarisation was detected from M 51, owing to severe Faraday depolarisation. Six extragalactic sources are detected in polarisation in the M 51 field of 4

  10. Continuum Halos in Nearby Galaxies -- an EVLA Survey (CHANG-ES) -- II: First Results on NGC 4631

    CERN Document Server

    Irwin, Judith; Benjamin, R A; Dettmar, Ralf-Juergen; English, Jayanne; Heald, George; Henriksen, Richard N; Johnson, Megan; Krause, Marita; Li, Jiang-Tao; Miskolczi, Arpad; Mora, Silvia Carolina; Murphy, E J; Oosterloo, Tom; Porter, Troy A; Rand, Richard J; Saikia, D J; Schmidt, Philip; Strong, A W; Walterbos, Rene; Wang, Q Daniel; Wiegert, Theresa

    2012-01-01

    We present the first results from the CHANG-ES survey, a new survey of 35 edge-on galaxies to search for both in-disk as well as extra-planar radio continuum emission. The motivation and science case for the survey are presented in a companion paper (Paper I). In this paper (Paper II), we outline the observations and data reduction steps required for wide-band calibration and mapping of EVLA data, including polarization, based on C-array test observations of NGC 4631. With modest on-source observing times (30 minutes at 1.5 GHz and 75 minutes at 6 GHz for the test data) we have achieved best rms noise levels of 22 and 3.5 $\\mu$Jy beam$^{-1}$ at 1.5 GHz and 6 GHz, respectively. New disk-halo features have been detected, among them two at 1.5 GHz that appear as loops in projection. We present the first 1.5 GHz spectral index map of NGC 4631 to be formed from a single wide-band observation in a single array configuration. This map represents tangent slopes to the intensities within the band centered at 1.5 GHz, ...

  11. The Star Formation in Radio Survey: GBT 33 GHz Observations of Nearby Galaxy Nuclei and Extranuclear Star-Forming Regions

    CERN Document Server

    Murphy, E J; Mason, B S; Condon, J J; Schinnerer, E; Aniano, G; Armus, L; Helou, G; Turner, J L; Jarrett, T H

    2012-01-01

    We present 33\\,GHz photometry of 103 galaxy nuclei and extranuclear star-forming complexes taken with the Green Bank Telescope (GBT) as part of the Star Formation in Radio Survey (SFRS). Among the sources without evidence for an AGN, and also having lower frequency radio data, we find a median thermal fraction at 33GHz of ~76% with a dispersion of ~24%. For all sources resolved on scales 90%. This suggests that the rest-frame 33GHz emission provides a sensitive measure of the ionizing photon rate from young star-forming regions, thus making it a robust star formation rate indicator. Taking the 33GHz star formation rates as a reference, we investigate other empirical calibrations relying on different combinations of warm 24\\mu m dust, total infrared (IR; 8-1000\\mu m), H\\alpha\\ line, and far-UV continuum emission. The recipes derived here generally agree with others found in the literature, albeit with a large dispersion that most likely stems from a combination of effects. Comparing the 33GHz to total IR flux ...

  12. First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

    CERN Document Server

    Miralles-Caballero, D; López-Sánchez, Á R; Rosales-Ortega, F F; Monreal-Ibero, A; Pérez-Montero, E; Kehrig, C; García-Benito, R; Sánchez, S F; Walcher, C J; Galbany, L; Iglesias-Páramo, J; Vílchez, J M; Delgado, R M González; van de Ven, G; Barrera-Ballesteros, J; Lyubenova, M; Meidt, S; Falcon-Barroso, J; Mast, D; Mendoza, M A

    2016-01-01

    The search of extragalactic regions with conspicuous presence of Wolf-Rayet (WR) stars outside the Local Group is challenging task due to the difficulties in detecting their faint spectral features. In this exploratory work, we develop a methodology to perform an automated search of WR signatures through a pixel-by-pixel analysis of integral field spectroscopy (IFS) data belonging to the Calar Alto Legacy Integral Field Area survey, CALIFA. This technique allowed us to build the first catalogue of Wolf-Rayet rich regions with spatially-resolved information, allowing to study the properties of these complexes in a 2D context. The detection technique is based on the identification of the blue WR bump (around He II 4686 {\\AA}, mainly associated to nitrogen-rich WR stars, WN) and the red WR bump (around C IV 5808 {\\AA} and associated to carbon-rich WR stars, WC) using a pixel-by-pixel analysis. We identified 44 WR-rich regions with blue bumps distributed in 25 galaxies of a total of 558. The red WR bump was ident...

  13. A high resolution view of the jet termination shock in a hot spot of the nearby radio galaxy Pictor A: implications for X-ray models of radio galaxy hot spots

    CERN Document Server

    Tingay, S J; Brunetti, G; Bondi, M

    2008-01-01

    Images made with the VLBA have resolved the region in a nearby radio galaxy, Pictor A, where the relativistic jet that originates at the nucleus terminates in an interaction with the intergalactic medium, a so-called radio galaxy hot spot. This image provides the highest spatial resolution view of such an object to date (16 pc), more than three times better than previous VLBI observations of similar objects. The north-west Pictor A hot spot is resolved into a complex set of compact components, seen to coincide with the bright part of the hot spot imaged at arcsecond-scale resolution with the VLA. In addition to a comparison with VLA data, we compare our VLBA results with data from the HST and Chandra telescopes, as well as new Spitzer data. The presence of pc-scale components in the hot spot, identifying regions containing strong shocks in the fluid flow, leads us to explore the suggestion that they represent sites of synchrotron X-ray production, contributing to the integrated X-ray flux of the hot spot, alo...

  14. The dusty heart of nearby active galaxies. I. High-spatial resolution mid-IR spectro-photometry of Seyfert galaxies

    CERN Document Server

    Hoenig, S F; Gandhi, P; Smette, A; Asmus, D; Duschl, W; Polletta, M; Weigelt, G

    2010-01-01

    We present 8-13 micron imaging and spectroscopy of 9 type 1 and 10 type 2 AGN obtained with the VLT/VISIR instrument at spatial resolution <100 pc. The emission from the host galaxy sources is resolved out in most cases. The silicate absorption features are moderately deep and emission features are shallow. We compare the mid-IR luminosities to AGN luminosity tracers and found that the mid-IR radiation is emitted quite isotropically. In two cases, IC5063 and MCG-3-34-64, we find evidence for extended dust emission in the narrow-line region. We confirm the correlation between observed silicate feature strength and Hydrogen column density recently found in Spitzer data. In a further step, our 3D clumpy torus model has been used to interpret the data. We show that the strength of the silicate feature and the mid-IR spectral index can be used to get reasonable constraints on the dust distribution in the torus. The mid-IR spectral index, alpha, is almost exclusively determined by the radial dust distribution po...

  15. CO(J=3-2) On-the-fly Mapping of the Nearby Spiral Galaxies NGC 628 and NGC 7793: Spatially-resolved CO(J=3-2) Star-formation Law

    CERN Document Server

    Muraoka, Kazuyuki; Yanagitani, Kazuki; Kaneko, Hiroyuki; Nakanishi, Kouichiro; Kuno, Nario; Sorai, Kazuo; Tosaki, Tomoka; Kohno, Kotaro

    2015-01-01

    We present the results of CO(J=3-2) on-the-fly mappings of two nearby non-barred spiral galaxies NGC 628 and NGC 7793 with the Atacama Submillimeter Telescope Experiment at an effective angular resolution of 25". We successfully obtained global distributions of CO(J=3-2) emission over the entire disks at a sub-kpc resolution for both galaxies. We examined the spatially-resolved (sub-kpc) relationship between CO(J=3-2) luminosities (L'CO(3-2)) and infrared (IR) luminosities (LIR) for NGC 628, NGC 7793, and M 83, and compared it with global luminosities of JCMT Nearby Galaxy Legacy Survey sample. We found a striking linear L'CO(3-2)-LIR correlation over the 4 orders of magnitude, and the correlation is consistent even with that for ultraluminous infrared galaxies and submillimeter selected galaxies. In addition, we examined the spatially-resolved relationship between CO(J=3-2) intensities (ICO(3-2)) and extinction-corrected star formation rates (SFRs) for NGC 628, NGC 7793, and M 83, and compared it with that f...

  16. The Sloan Lens ACS Survey. III. The structure and formation of early-type galaxies and their evolution since z approximate to 1

    NARCIS (Netherlands)

    Koopmans, Leon V. E.; Treu, Tommaso; Bolton, Adam S.; Burles, Scott; Moustakas, Leonidas A.

    2006-01-01

    We present a joint gravitational lensing and stellar-dynamical analysis of 15 massive field early-type galaxies selected from the Sloan Lens ACS (SLACS) Survey. The following numerical results are found: (1) A joint likelihood gives an average logarithmic density slope for the total mass density of

  17. The HST/ACS Coma Cluster Survey. X. Nuclear star clusters in low-mass early-type galaxies: scaling relations

    CERN Document Server

    Brok, Mark den; Seth, Anil; Balcells, Marc; Dominguez, Lilian; Graham, Alister W; Carter, David; Erwin, Peter; Ferguson, Henry C; Goudfrooij, Paul; Guzman, Rafael; Hoyos, Carlos; Jogee, Shardha; Lucey, John; Phillipps, Steven; Puzia, Thomas; Valentijn, Edwin; Kleijn, Gijs Verdoes; Weinzirl, Tim

    2014-01-01

    We present scaling relations between structural properties of nuclear star clusters and their host galaxies for a sample of early-type dwarf galaxies observed as part of the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Coma Cluster Survey. We have analysed the light profiles of 200 early-type dwarf galaxies in the magnitude range $16.0 < m_{F814W} < 22.6 $ mag, corresponding to $-19.0 < M_{F814W} < -12.4 $ mag. Nuclear star clusters are detected in 80% of the galaxies, thus doubling the sample of HST-observed early-type dwarf galaxies with nuclear star clusters. \\changed{We confirm that the} nuclear star cluster detection fraction decreases strongly toward faint magnitudes. The luminosities of nuclear star clusters do not scale linearly with host galaxy luminosity. A linear fit yields L$_{nuc} \\sim $L$_{gal}^{0.57\\pm0.05}$. The nuclear star cluster-host galaxy luminosity scaling relation for low-mass early-type dwarf galaxies is consistent with formation by globular cluster accre...

  18. FINDING η CAR ANALOGS IN NEARBY GALAXIES USING Spitzer. II. IDENTIFICATION OF AN EMERGING CLASS OF EXTRAGALACTIC SELF-OBSCURED STARS

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Rubab; Kochanek, C. S.; Stanek, K. Z.; Gerke, Jill, E-mail: ckochanek@astronomy.ohio-state.edu [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

    2015-02-01

    Understanding the late-stage evolution of the most massive stars such as η Carinae is challenging because no true analogs of η Car have been clearly identified in the Milky Way or other galaxies. In Khan et al., we utilized Spitzer IRAC images of 7 nearby (≲ 4 Mpc) galaxies to search for such analogs, and found 34 candidates with flat or red mid-IR spectral energy distributions. Here, in Paper II, we present our characterization of these candidates using multi-wavelength data from the optical through the far-IR. Our search detected no true analogs of η Car, which implies an eruption rate that is a fraction 0.01 ≲ F ≲ 0.19 of the core-collapse supernova (ccSN) rate. This is roughly consistent with each M {sub ZAMS} ≳ 70 M {sub ☉} star undergoing one or two outbursts in its lifetime. However, we do identify a significant population of 18 lower luminosity (log (L/L {sub ☉}) ≅ 5.5-6.0) dusty stars. Stars enter this phase at a rate that is a fraction 0.09 ≲ F ≲ 0.55 of the ccSN rate, and this is consistent with all 25 < M {sub ZAMS} < 60 M {sub ☉} stars undergoing an obscured phase at most lasting a few thousand years once or twice. These phases constitute a negligible fraction of post-main-sequence lifetimes of massive stars, which implies that these events are likely to be associated with special periods in the evolution of the stars. The mass of the obscuring material is of order ∼M {sub ☉}, and we simply do not find enough heavily obscured stars for theses phases to represent more than a modest fraction (∼10% not ∼50%) of the total mass lost by these stars. In the long term, the sources that we identified will be prime candidates for detailed physical analysis with the James Webb Space Telescope.

  19. 棒对星系核区恒星形成活动的影响%The Effect of Bar on Nuclear Star-forming Activities in Nearby Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    汪潋

    2009-01-01

    利用SDSS光谱,研究了IRAS卫星亮红外源星表中的盘状星系中的恒星形成性质,并着重探讨了棒对星系核区恒星形成活动的影响.利用星族合成的方法得到了每个样本星系核区的恒星组成性质、恒星形成活动的强度等信息,并比较了星系整体和核区恒星形成性质的差异.得到的结论:除去相互作用,样本中的棒星系显示出比非棒旋星系更强的核区恒星形成活动和更多的年轻星族成分.%By using SDSS spectra, we have studied nuclear star-forming properties of nearby spiral galaxies selected from Infrared Revised Bright Galaxy Sample, and try to find the effect of bar structure on star-forming activities in the nuclear regions of nearby galaxies. The composition of stellar population and the strength of star formation activities in the sample galaxies are acquired by using stellar population synthesis code ?STARLIGHT, and the star formation properties in nuclear regions are compared with that of the whole galaxies. We find that the star formation in barred spiral galaxies is more intensive than non-barred ones and barred spirals show much younger stellar populations.

  20. The Sloan Lens ACS Survey. XI. Beyond Hubble resolution: size, luminosity and stellar mass of compact lensed galaxies at intermediate redshift

    CERN Document Server

    Newton, Elisabeth R; Auger, Matthew W; Gavazzi, Raphael; Bolton, Adam S; Koopmans, Leon V E; Moustakas, Leonidas A

    2011-01-01

    We exploit the strong lensing effect to explore the properties of intrinsically faint and compact galaxies at intermediate redshift, at the highest possible resolution at optical wavelengths. Our sample consists of 46 strongly-lensed emission line galaxies discovered by the Sloan Lens ACS (SLACS) Survey. The galaxies have been imaged at high resolution with HST in three bands (V_HST, I_814 and H_160), allowing us to infer their size, luminosity, and stellar mass using stellar population synthesis models. Lens modeling is performed using a new fast and robust code, klens, which we test extensively on real and synthetic non-lensed galaxies, and also on simulated galaxies multiply-imaged by SLACS- like galaxy-scale lenses. Our tests show that our measurements of galaxy size, flux, and Sersic index are robust and accurate, even for objects intrinsically smaller than the HST point spread function. The median magnification is 8.8, with a long tail that extends to magnifications above 40. Modeling the SLACS sources ...

  1. Cleaning spectroscopic samples of stars in nearby dwarf galaxies : The use of the nIR Mg I line to weed out Milky Way contaminants

    NARCIS (Netherlands)

    Battaglia, G.; Starkenburg, E.

    2012-01-01

    Dwarf galaxies provide insight into the processes of star formation and chemical enrichment at the low end of the galaxy mass function, as well as into the clustering of dark matter on small scales. In studies of Local Group dwarf galaxies, spectroscopic samples of individual stars are used to deriv

  2. Observation of a nearby early merging cluster of galaxies, CIZA J1358.9-4750: new born shocks in the ICM

    Science.gov (United States)

    Kato, Yuichi; Nakazawa, Kazuhiro; Akahori, Takuya; Gu, Liyi; Takizawa, Motokazu; Fujita, Yutaka; Makishima, Kazuo; Simionescu, Aurora

    2016-04-01

    Cluster merger events drive shocks in the intra-cluster plasma and activate non-thermal phenomena such as particle acceleration, magnetic field amplification, and turbulence. However, details of these processes are not well known because of a lack of observations. The known examples of merging clusters are mostly in late merger phases, wherein the shocks have already reached the low-density outer regions. Therefore, finding nearby merging clusters in early phases, in which the shock is still located in dense regions, is of great importance.In order to find suitable objects, we searched the CIZA catalog, which collects X-ray detected cluster candidates located behind the Zone of Avoidance, near the Galactic ridge. We found a very promising merging-cluster candidate CIZA J1358.9-4750, with a redshift of 0.07. It consists of a close pair of X-ray clusters of galaxies in North-west(NW) and South-east(SE), which are connected by an X-ray bright ``bridge’’ region in between. We observed this object with Suzaku and Chandra, and analyzed its archival short exposure XMM-Newton data. The Suzaku data revealed that the NW and SE clusters have temperatures of 5.2±0.2 keV and 4.6±0.2 keV, respectively. The bridge region was found to have a 1.6 times higher temperature, 9.2±1.5 keV. In the existing XMM-Newton data, we found an abrupt brightness jump coinciding in position with the Suzaku high-temperature region. With additional Chandra data, we found a bright plateau with a width of 2’, i.e. 170 kpc. The front and back jumps are presumably the forward and reverse shocks between the two clusters. Therefore, the object is likely to be a rather symmetric shock system, in which two clusters of similar masses are colliding. The Mach number of the collision was derived as 1.3±0.2 and 1.17±0.04 from the Suzaku temperature jump and the Chandra brightness jump, respectively. This Mach number and the X-ray temperature give the shock velocity as 1200 km/s. It can be combined with

  3. Metallicities of Emission-Line Galaxies from HST ACS PEARS and HST WFC3 ERS Grism Spectroscopy at 0.6 < z < 2.4

    CERN Document Server

    Xia, Lifang; Rhoads, James; Pirzkal, Nor; Straughn, Amber; Finkelstein, Steven; Cohen, Seth; Kuntschner, Harald; Kümmel, Martin; Walsh, Jeremy; Windhorst, Rogier A; O'Connell, Robert

    2012-01-01

    Galaxies selected on the basis of their emission line strength show low metallicities, regardless of their redshifts. We conclude this from a sample of faint galaxies at redshifts between 0.6 < z < 2.4, selected by their prominent emission lines in low-resolution grism spectra in the optical with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) and in the near-infrared using Wide-Field Camera 3 (WFC3). Using a sample of 11 emission line galaxies (ELGs) at 0.6 < z < 2.4 with luminosities of -22 < M_B < -19, which have [OII], H\\beta, and [OIII] line flux measurements from the combination of two grism spectral surveys, we use the R23 method to derive the gas-phase oxygen abundances: 7.5 < 12+log(O/H) < 8.5. The galaxy stellar masses are derived using Bayesian based Markov Chain Monte Carlo (\\piMC^2) fitting of their Spectral Energy Distribution (SED), and span the mass range 8.1 < log(M_*/M_\\sun) < 10.1. These galaxies show a mass-metallicity (M-L) and Lumin...

  4. The MASSIVE Survey. IV. The X-ray Halos of the Most Massive Early-type Galaxies in the Nearby Universe

    Science.gov (United States)

    Goulding, Andy D.; Greene, Jenny E.; Ma, Chung-Pei; Veale, Melanie; Bogdan, Akos; Nyland, Kristina; Blakeslee, John P.; McConnell, Nicholas J.; Thomas, Jens

    2016-08-01

    Studies of the physical properties of local elliptical galaxies are shedding new light on galaxy formation. Here we present the hot-gas properties of 33 early-type systems within the MASSIVE galaxy survey that have archival Chandra X-ray observations, and we use these data to derive X-ray luminosities ({L}{{X,gas}}) and plasma temperatures ({T}{{gas}}) for the diffuse gas components. We combine this with the {{ATLAS}}{{3D}} survey to investigate the X-ray-optical properties of a statistically significant sample of early-type galaxies across a wide range of environments. When X-ray measurements are performed consistently in apertures set by the galaxy stellar content, we deduce that all early types (independent of galaxy mass, environment, and rotational support) follow a universal scaling law such that {L}{{X,gas}}\\propto {T}{{gas}}˜ 4.5. We further demonstrate that the scatter in {L}{{X,gas}} around both K-band luminosity (L K ) and the galaxy stellar velocity dispersion ({σ }e) is primarily driven by {T}{{gas}}, with no clear trends with halo mass, radio power, or angular momentum of the stars. It is not trivial to tie the gas origin directly to either stellar mass or galaxy potential. Indeed, our data require a steeper relation between {L}{{X,gas}},{L}K, and {σ }e than predicted by standard mass-loss models. Finally, we find that {T}{{gas}} is set by the galaxy potential inside the optical effective radius. We conclude that within the innermost 10-30 kpc region, early types maintain pressure-supported hot gas, with a minimum {T}{{gas}} set by the virial temperature, but the majority show evidence for additional heating.

  5. The ACS LCID Project XI. On the early time resolution of LG dwarf galaxy SFHs: Comparing the effects of reionization in models with observations

    CERN Document Server

    Aparicio, Antonio; Skillman, Evan; Cassisi, Santi; Mayer, Lucio; Navarro, Julio; Cole, Andrew; Gallart, Carme; Monelli, Matteo; Weisz, Daniel; Bernard, Edouard; Dolphin, Andrew; Stetson, Peter

    2016-01-01

    The analysis of the early star formation history (SFH) of nearby galaxies, obtained from their resolved stellar populations is relevant as a test for cosmological models. However, the early time resolution of observationally derived SFHs is limited by several factors. Thus, direct comparison of observationally derived SFHs with those derived from theoretical models of galaxy formation is potentially biased. Here we investigate and quantify this effect. For this purpose, we analyze the duration of the early star formation activity in a sample of four Local Group dwarf galaxies and test whether they are consistent with being true fossils of the pre-reionization era; i.e., if the quenching of their star formation occurred before cosmic reionization by UV photons was completed. Two classical dSph (Cetus and Tucana) and two dTrans (LGS-3 and Phoenix) isolated galaxies with total stellar masses between $1.3\\times 10^6$ to $7.2\\times 10^6$ M$_\\odot$ have been studied. Accounting for time resolution effects, the SFHs...

  6. NIHAO V: Too big doesn't fail -- reconciling the conflict between LCDM predictions and the circular velocities of nearby field galaxies

    CERN Document Server

    Dutton, Aaron A; Frings, Jonas; Wang, Liang; Stinson, Gregory S; Penzo, Camilla; Kang, Xi

    2015-01-01

    We compare the half-light circular velocities, V_{1/2}, of dwarf galaxies in the Local Group to the predicted circular velocity curves of galaxies in the NIHAO suite of LCDM simulations. We use a subset of 34 simulations in which the central galaxy has a stellar luminosity in the range 0.5 x 10^5 2 x 10^6 L_{sun}. For lower luminosities our simulations predict very little halo response, and tend to over predict the observed circular velocities. In the context of LCDM, this could signal the increased stochasticity of star formation in haloes below M_{halo} \\sim 10^{10} M_{sun}, or the role of environmental effects. Thus, haloes that are "too big to fail", do not fail LCDM, but haloes that are "too small to pass" (the galaxy formation threshold) provide a future test of LCDM.

  7. Structures of Local Galaxies Compared to High Redshift Star-forming Galaxies

    CERN Document Server

    Petty, Sara M; Gallagher, John S; Gardner, Jonathan P; Lotz, Jennifer M; Mountain, C Matt; Smith, Linda J

    2009-01-01

    The rest-frame far-ultraviolet (FUV) morphologies of 8 nearby interacting and starburst galaxies (Arp 269, M 82, Mrk 8, NGC 520, NGC 1068, NGC 3079, NGC 3310, NGC 7673) are compared with 54 galaxies at z ~ 1.5 and 46 galaxies at z ~ 4 observed in the GOODS-ACS field. The nearby sample is artificially redshifted to z ~ 1.5 and 4. We compare the simulated galaxy morphologies to real z ~ 1.5 and 4 UV-bright galaxy morphologies. We calculate the Gini coefficient (G), the second-order moment of the brightest 20% of the galaxy's flux (M_20), and the Sersic index (n). We explore the use of nonparametric methods with 2D profile fitting and find the combination of M_20 with n an efficient method to classify galaxies as having merger, exponential disk, or bulge-like morphologies. When classified according to G and M_20, 20/30% of real/simulated galaxies at z ~ 1.5 and 37/12% at z ~ 4 have bulge-like morphologies. The rest have merger-like or intermediate distributions. Alternatively, when classified according to the Se...

  8. The Atlas3D project - VII. A new look at the morphology of nearby galaxies: the kinematic morphology-density relation

    CERN Document Server

    Cappellari, Michele; Krajnovic, Davor; McDermid, Richard M; Serra, Paolo; Alatalo, Katherine; Blitz, Leo; Bois, Maxime; Bournaud, Frederic; Bureau, M; Davies, Roger L; Davis, Timothy A; de Zeeuw, P T; Khochfar, Sadegh; Kuntschner, Harald; Lablanche, Pierre-Yves; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Weijmans, Anne-Marie; Young, Lisa M

    2011-01-01

    We look at the morphology of fast and slow rotator early-type galaxies. Edge-on fast rotators are lenticular galaxies. They appear like spiral galaxies with the gas and dust removed, and in some cases are flat ellipticals with disky isophotes. Fast rotators are often barred and span the same full range of bulge fractions as spiral galaxies. The slow rotators are rounder and are generally consistent with being genuine, namely spheroidal-like, elliptical galaxies. We propose a revision to the tuning-fork diagram by Hubble as it gives a misleading description of ETGs. We study for the first time the kinematic morphology-density T-Sigma relation using fast and slow rotators to replace lenticulars and ellipticals. We find that our relation is cleaner than using classic morphology. Slow rotators are nearly absent at the lowest density environments [f(SR)<2%] and generally constitute a small fraction [f(SR)~4%] of the total galaxy population in the environments explored by our survey, with the exception of the de...

  9. The X-ray Zurich environmental study (X-zens). I. Chandra and XMM-Newton observations of active galactic nuclei in galaxies in nearby groups

    Energy Technology Data Exchange (ETDEWEB)

    Silverman, J. D. [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, the University of Tokyo (Kavli IPMU, WPI), Kashiwa 277-8583 (Japan); Miniati, F.; Carollo, C. M.; Cibinel, A.; Lilly, S. J.; Schawinski, K. [Institute for Astronomy, ETH Zürich, CH-8093, Zürich (Switzerland); Finoguenov, A., E-mail: john.silverman@ipmu.jp [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-00014 Helsinki (Finland)

    2014-01-01

    We describe X-ray observations with Chandra and XMM-Newton of 18 M {sub group} ∼ 1-6 × 10{sup 13} M {sub ☉}, z ∼ 0.05 galaxy groups from the Zurich ENvironmental Study. The X-ray data aim at establishing the frequency and properties, unaffected by host galaxy dilution and obscuration, of active galactic nuclei (AGNs) in central and satellite galaxies, also as a function of halo-centric distance. X-ray point-source detections are reported for 22 of the 177 galaxies, down to a sensitivity level of f {sub 0.5} {sub –} {sub 8} {sub keV} ∼ 5 × 10{sup –15} erg cm{sup –2} s{sup –1}, corresponding to a limiting luminosity of L {sub 0.5} {sub –} {sub 8} {sub keV} ∼ 3 × 10{sup 40} erg s{sup –1}. With the majority of the X-ray sources attributed to AGNs of low-to-moderate levels (L/L {sub Edd} ≳ 10{sup –4}), we discuss the detection rate in the context of the occupation of AGNs to halos of this mass scale and redshift and compare the structural and morphological properties between AGN-active and non-active galaxies. At galaxy mass scales <10{sup 11} M {sub ☉}, central galaxies appear to be a factor of ∼4 more likely to host AGNs than satellite galaxies of similar mass. This effect, coupled with the tendency for AGNs to be hosted by massive galaxies, explains the (weak) trend for AGNs to be preferentially found in the inner parts of group halos, with no detectable trend with halo-centric distance in the frequency of AGNs within the satellite population. Finally, our data indicate that the rate of decline with redshift of AGN activity in galaxy groups matches that of the global AGN population, indicating that either AGN activity occurs preferentially in group halos or that the evolution rate is independent of halo mass.

  10. The X-ray Zurich Environmental Study (X-ZENS). I. Chandra and XMM-Newton observations of AGNs in galaxies in nearby groups

    CERN Document Server

    Silverman, J D; Finoguenov, A; Carollo, C M; Cibinel, A; Lilly, S J; Schawinski, K

    2013-01-01

    We describe X-ray observations with Chandra and XMM-Newton of 18 galaxy groups (M_group ~ 1-6x10^13 Msolar, z~0.05) from the Zurich Environmental Study (ZENS). We aim to establish the frequency and properties, unaffected by host galaxy dilution and obscuration, of AGNs in central and satellite galaxy members, also as a function of halo-centric distance. X-ray point-source detections are reported for 22 of 177 observed galaxies, down to a limit of f_(0.5-8 keV) ~ 5x10^-15 erg cm^-2 s^-1, corresponding to a limiting luminosity of L_(0.5-8 keV)~3x10^40 erg s^-1. With the majority of the X-ray sources attributed to AGNs of low-to-moderate levels (L/L_Edd>~10^-4), we discuss the detection rate in the context of the occupation of AGNs to halos of this mass scale and redshift, and compare the structural/morphological properties between AGN-active and non-active galaxies of different rank and location within the group halos. We see a slight tendency for AGN hosts to have either relatively brighter/denser disks (or re...

  11. Faint dwarfs in nearby groups

    Energy Technology Data Exchange (ETDEWEB)

    Speller, Ryan; Taylor, James E., E-mail: rspeller@uwaterloo.ca, E-mail: taylor@uwaterloo.ca [Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2014-06-20

    The number and distribution of dwarf satellite galaxies remain a critical test of cold dark matter-dominated structure formation on small scales. Until recently, observational information about galaxy formation on these scales has been limited mainly to the Local Group. We have searched for faint analogues of Local Group dwarfs around nearby bright galaxies, using a spatial clustering analysis of the photometric catalog of the Sloan Digital Sky Survey (SDSS) Data Release 8. Several other recent searches of SDSS have detected clustered satellite populations down to Δm{sub r} ≡ (m{sub r,} {sub sat} – m{sub r,} {sub main}) ∼ 6-8, using photometric redshifts to reduce background contamination. SDSS photometric redshifts are relatively imprecise, however, for faint and nearby galaxies. Instead, we use angular size to select potential nearby dwarfs and consider only the nearest isolated bright galaxies as primaries. As a result, we are able to detect an excess clustering signal from companions down to Δm{sub r} = 12, 4 mag fainter than most recent studies. We detect an overdensity of objects at separations <400 kpc, corresponding to about 4.6 ± 0.5 satellites per central galaxy, consistent with the satellite abundance expected from the Local Group, given our selection function. Although the sample of satellites detected is incomplete by construction, since it excludes the least and most compact dwarfs, this detection provides a lower bound on the average satellite luminosity function, down to luminosities corresponding to the faintest ''classical'' dwarfs of the Local Group.

  12. The ACS LCID Project. XI. On the Early Time Resolution of SFHs of Local Group Dwarf Galaxies: Comparing the Effects of Reionization in Models with Observations

    Science.gov (United States)

    Aparicio, Antonio; Hidalgo, Sebastian L.; Skillman, Evan; Cassisi, Santi; Mayer, Lucio; Navarro, Julio; Cole, Andrew; Gallart, Carme; Monelli, Matteo; Weisz, Daniel; Bernard, Edouard; Dolphin, Andrew; Stetson, Peter

    2016-05-01

    The analysis of the early star formation history (SFH) of nearby galaxies, obtained from their resolved stellar populations, is relevant as a test for cosmological models. However, the early time resolution of observationally derived SFHs is limited by several factors. Thus, direct comparison of observationally derived SFHs with those derived from theoretical models of galaxy formation is potentially biased. Here we investigate and quantify this effect. For this purpose, we analyze the duration of the early star formation activity in a sample of four Local Group dwarf galaxies and test whether they are consistent with being true fossils of the pre-reionization era; i.e., if the quenching of their star formation occurred before cosmic reionization by UV photons was completed. Two classical dSph (Cetus and Tucana) and two dTrans (LGS-3 and Phoenix) isolated galaxies with total stellar masses between 1.3× {10}6 and 7.2× {10}6 {M}ȯ have been studied. Accounting for time resolution effects, the SFHs peak as much as 1.25 Gyr earlier than the optimal solutions. Thus, this effect is important for a proper comparison of model and observed SFHs. It is also shown that none of the analyzed galaxies can be considered a true fossil of the pre-reionization era, although it is possible that the outer regions of Cetus and Tucana are consistent with quenching by reionization. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #10505.

  13. The ACS LCID Project. XI. On the Early Time Resolution of SFHs of Local Group Dwarf Galaxies: Comparing the Effects of Reionization in Models with Observations

    Science.gov (United States)

    Aparicio, Antonio; Hidalgo, Sebastian L.; Skillman, Evan; Cassisi, Santi; Mayer, Lucio; Navarro, Julio; Cole, Andrew; Gallart, Carme; Monelli, Matteo; Weisz, Daniel; Bernard, Edouard; Dolphin, Andrew; Stetson, Peter

    2016-05-01

    The analysis of the early star formation history (SFH) of nearby galaxies, obtained from their resolved stellar populations, is relevant as a test for cosmological models. However, the early time resolution of observationally derived SFHs is limited by several factors. Thus, direct comparison of observationally derived SFHs with those derived from theoretical models of galaxy formation is potentially biased. Here we investigate and quantify this effect. For this purpose, we analyze the duration of the early star formation activity in a sample of four Local Group dwarf galaxies and test whether they are consistent with being true fossils of the pre-reionization era; i.e., if the quenching of their star formation occurred before cosmic reionization by UV photons was completed. Two classical dSph (Cetus and Tucana) and two dTrans (LGS-3 and Phoenix) isolated galaxies with total stellar masses between 1.3× {10}6 and 7.2× {10}6 {M}⊙ have been studied. Accounting for time resolution effects, the SFHs peak as much as 1.25 Gyr earlier than the optimal solutions. Thus, this effect is important for a proper comparison of model and observed SFHs. It is also shown that none of the analyzed galaxies can be considered a true fossil of the pre-reionization era, although it is possible that the outer regions of Cetus and Tucana are consistent with quenching by reionization. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #10505.

  14. A statistical study of nearby galaxies; 1, NIR growth curves and optical-to-NIR colors as a function of type, luminosity and inclination

    CERN Document Server

    Fioc, M; Fioc, Michel; Rocca-Volmerange, Brigitte

    1999-01-01

    Growth curves of the near-infrared (NIR) magnitude as a function of the aperture have been built and used to derive NIR total magnitudes from aperture data taken from the literature. By cross-correlating with optical and redshift data, absolute magnitudes and optical-to-NIR colors have been computed for some 1000 galaxies of different types. Significant color gradients are observed, underlining that small aperture colors may lead to a biased picture of the stellar populations of galaxies. A statistical analysis using various estimators taking into account the intrinsic scatter has been performed to establish relations between the colors, the morphological type, the inclination or the shape, and the intrinsic luminosity. The combination of the optical and the NIR should obviously improve our understanding of the evolution of galaxies. Despite the intrinsic scatter, especially among star-forming galaxies, optical-to-NIR colors show a very well defined sequence with type, blueing by 1.3 mag from ellipticals to i...

  15. THE STRUCTURE OF NUCLEAR STAR CLUSTERS IN NEARBY LATE-TYPE SPIRAL GALAXIES FROM HUBBLE SPACE TELESCOPE WIDE FIELD CAMERA 3 IMAGING

    Energy Technology Data Exchange (ETDEWEB)

    Carson, Daniel J.; Barth, Aaron J. [Department of Physics and Astronomy, University of California Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Seth, Anil C.; Brok, Mark den [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Cappellari, Michele [Sub-Department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Peyton Hall—Ivy Lane, Princeton, NJ 08544 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Neumayer, Nadine [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

    2015-05-15

    We obtained Hubble Space Telescope/Wide Field Camera 3 imaging of a sample of ten of the nearest and brightest nuclear clusters (NCs) residing in late-type spiral galaxies, in seven bands that span the near-UV to the near-IR. Structural properties of the clusters were measured by fitting two-dimensional surface brightness profiles to the images using GALFIT. The clusters exhibit a wide range of structural properties, with F814W absolute magnitudes that range from −11.2 to −15.1 mag and F814W effective radii that range from 1.4 to 8.3 pc. For 6 of the 10 clusters in our sample, we find changes in the effective radius with wavelength, suggesting radially varying stellar populations. In four of the objects, the effective radius increases with wavelength, indicating the presence of a younger population that is more concentrated than the bulk of the stars in the cluster. However, we find a general decrease in effective radius with wavelength in two of the objects in our sample, which may indicate extended, circumnuclear star formation. We also find a general trend of increasing roundness of the clusters at longer wavelengths, as well as a correlation between the axis ratios of the NCs and their host galaxies. These observations indicate that blue disks aligned with the host galaxy plane are a common feature of NCs in late-type galaxies, but are difficult to detect in galaxies that are close to face-on. In color–color diagrams spanning the near-UV through the near-IR, most of the clusters lie far from single-burst evolutionary tracks, showing evidence for multi-age populations. Most of the clusters have integrated colors consistent with a mix of an old population (>1 Gyr) and a young population (∼100–300 Myr). The wide wavelength coverage of our data provides a sensitivity to populations with a mix of ages that would not be possible to achieve with imaging in optical bands only. The surface brightness profiles presented in this work will be used for future

  16. The Structure of Nuclear Star Clusters in Nearby Late-type Spiral Galaxies from Hubble Space Telescope Wide Field Camera 3 Imaging

    Science.gov (United States)

    Carson, Daniel J.; Barth, Aaron J.; Seth, Anil C.; den Brok, Mark; Cappellari, Michele; Greene, Jenny E.; Ho, Luis C.; Neumayer, Nadine

    2015-05-01

    We obtained Hubble Space Telescope/Wide Field Camera 3 imaging of a sample of ten of the nearest and brightest nuclear clusters (NCs) residing in late-type spiral galaxies, in seven bands that span the near-UV to the near-IR. Structural properties of the clusters were measured by fitting two-dimensional surface brightness profiles to the images using GALFIT. The clusters exhibit a wide range of structural properties, with F814W absolute magnitudes that range from ‑11.2 to ‑15.1 mag and F814W effective radii that range from 1.4 to 8.3 pc. For 6 of the 10 clusters in our sample, we find changes in the effective radius with wavelength, suggesting radially varying stellar populations. In four of the objects, the effective radius increases with wavelength, indicating the presence of a younger population that is more concentrated than the bulk of the stars in the cluster. However, we find a general decrease in effective radius with wavelength in two of the objects in our sample, which may indicate extended, circumnuclear star formation. We also find a general trend of increasing roundness of the clusters at longer wavelengths, as well as a correlation between the axis ratios of the NCs and their host galaxies. These observations indicate that blue disks aligned with the host galaxy plane are a common feature of NCs in late-type galaxies, but are difficult to detect in galaxies that are close to face-on. In color–color diagrams spanning the near-UV through the near-IR, most of the clusters lie far from single-burst evolutionary tracks, showing evidence for multi-age populations. Most of the clusters have integrated colors consistent with a mix of an old population (>1 Gyr) and a young population (∼100–300 Myr). The wide wavelength coverage of our data provides a sensitivity to populations with a mix of ages that would not be possible to achieve with imaging in optical bands only. The surface brightness profiles presented in this work will be used for future

  17. The SINFONI Nearby Elliptical Lens Locator Survey: Discovery of two new low-redshift strong lenses and implications for the initial mass function in giant early-type galaxies

    CERN Document Server

    Smith, Russell J; Conroy, Charlie

    2015-01-01

    We present results from a blind survey to identify strong gravitational lenses among the population of low-redshift early-type galaxies. The SINFONI Nearby Elliptical Lens Locator Survey (SNELLS) uses integral-field infrared spectroscopy to search for lensed emission line sources behind massive lens candidates at $z$300 km/s) and \\alpha-element abundances ([Mg/Fe]>0.3). From the lensing configurations we derive total J-band mass-to-light ratios of 1.8$\\pm$0.1, 2.1$\\pm$0.1 and 1.9$\\pm$0.2 within the $\\sim$2 kpc Einstein radius. Correcting for estimated dark-matter contributions, and comparing to stellar population models with a Milky Way (Kroupa) initial mass function (IMF), we determine the "mass excess factor", \\alpha. Assuming the lens galaxies have "old" stellar populations (10$\\pm$1 Gyr), the average IMF mass factor is $\\langle\\alpha\\rangle$=1.10$\\pm$0.08$\\pm$0.10, where the first error is random and the second is systematic. If we instead fit the stellar populations from 6dF optical survey spectra, all t...

  18. Joint XMM-Newton and Chandra Observations of the NGC 1407/1400 Complex: a Tail of an Early-Type Galaxy and a Tale of a Nearby Merging Group

    CERN Document Server

    Su, Yuanyuan; White, Raymond; Irwin, Jimmy

    2014-01-01

    The nearby group centered on its bright central galaxy NGC 1407 has been suggested to be an unusually dark system from previous kinematic studies. It is also known for hosting a bright galaxy, NGC 1400, with a large radial velocity (1200 km s$^{-1}$) with respect to the group center. Previous ROSAT X-ray observations revealed an extended region of enhanced surface brightness just eastward of NGC 1400. We investigate the NGC 1407/1400 complex with XMM-Newton and Chandra observations. We find that the temperature and metallicity of the enhanced region are different (cooler and more metal rich) than those of the surrounding group gas, but consistent with those of the ISM in NGC 1400. The relative velocity of NGC 1400 is large enough that much of its ISM could have been ram pressure stripped while plunging through the group atmosphere. We conclude that the enhanced region is likely to be hot gas stripped from the ISM of NGC 1400. We constrain the motion of NGC 1400 using the the pressure jump at its associated st...

  19. THE ACS LCID PROJECT: ON THE ORIGIN OF DWARF GALAXY TYPES—A MANIFESTATION OF THE HALO ASSEMBLY BIAS?

    Energy Technology Data Exchange (ETDEWEB)

    Gallart, Carme; Monelli, Matteo; Aparicio, Antonio; Battaglia, Giuseppina; Drozdovsky, Igor; Hidalgo, Sebastian L. [Instituto de Astrofísica de Canarias, La Laguna, Tenerife (Spain); Mayer, Lucio [Institut für Theoretische Physik, University of Zurich, Zürich (Switzerland); Bernard, Edouard J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Cassisi, Santi [INAF-Osservatorio Astronomico di Collurania, Teramo (Italy); Cole, Andrew A. [School of Physical Sciences, University of Tasmania, Private Bag 37, Hobart, TAS 7005 (Australia); Dolphin, Andrew E. [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85706 (United States); Navarro, Julio F. [Department of Physics and Astronomy, University of Victoria, PO Box 1700, STN CSC, Victoria, BC V8W 3P6 (Canada); Salvadori, Stefania [Kapteyn Astronomical Institute, Landleven 12, NL-9747 AD Groningen (Netherlands); Skillman, Evan D. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN (United States); Stetson, Peter B. [Herzberg Astronomy and Astrophysics, National Research Council Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Weisz, Daniel R., E-mail: monelli@iac.es [Astronomy Department, University of Washington, Box 351580, Seattle, WA (United States)

    2015-10-01

    We discuss how knowledge of the whole evolutionary history of dwarf galaxies, including details on the early star formation events, can provide insight on the origin of the different dwarf galaxy types. We suggest that these types may be imprinted by the early conditions of formation rather than only being the result of a recent morphological transformation driven by environmental effects. We present precise star formation histories of a sample of Local Group dwarf galaxies, derived from color–magnitude diagrams reaching the oldest main-sequence turnoffs. We argue that these galaxies can be assigned to two basic types: fast dwarfs that started their evolution with a dominant and short star formation event and slow dwarfs that formed a small fraction of their stars early and have continued forming stars until the present time (or almost). These two different evolutionary paths do not map directly onto the present-day morphology (dwarf spheroidal versus dwarf irregular). Slow and fast dwarfs also differ in their inferred past location relative to the Milky Way and/or M31, which hints that slow dwarfs were generally assembled in lower-density environments than fast dwarfs. We propose that the distinction between a fast and slow dwarf galaxy primarily reflects the characteristic density of the environment where they form. At a later stage, interaction with a large host galaxy may play a role in the final gas removal and ultimate termination of star formation.

  20. Studies of luminous stars in nearby galaxies. III. Comments on the evolution of the most massive stars in the Milky Way and the large magellanic cloud

    International Nuclear Information System (INIS)

    An empirical comparison of the observed H-R diagrams for the supergiants in our region of the Galaxy and the Large Magellanic Cloud reveals comparable distributions of spectral types and luminosities in the two galaxies. Supergiants of similar spectral types have the same luminosities, except for the A-type stars, where selection effects may be important. These results suggest that the same basic physical processes govern the evolution of the most massive stars in the two galaxies.Variations in the blue-to-red supergiant ratio with galactocentric distance and with luminosity involve chemical composition gradients and varying rates of mass loss. Since the relative numbers of the most luminous stars are more sensitive to mass loss, the B/R ratio from the less luminous supergiants may be a better indicator of galactic abundance gradients.The upper luminosity boundary for both the galactic and the LMC supergiants is characterized by (1) decreasing luminosity with decreasing temperature for the hottest stars and (2) an upper limit to the luminosity near M/sub bol/approx. =-9.5 to -10 mag for stars cooler than 15,000 K. We suggest that the observed luminosity limits are due primarily to the effects of large mass loss on the evolution of the most massive stars. The examples of eta Car and P Cyg suggest that mass-loss rates can be very rapid and unsteady--higher on the average than presently observed for most of the hot supergiants. The evolution of stars greater than 60 M/sub sun/ to cooler temperatures is consequently limited by instabilities and the accompanying high mass loss. An initial mass near 50--60 M/sub sun/ may be an empirical upper limit to the mass at which a star can evolve to the region of the M supergiants and probably accounts for the observed upper bound to the luminosities of the cooler supergiants