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Sample records for ii absorbing galaxies

  1. Mg II Absorbing Galaxies: Morphologies and Kinematics

    CERN Document Server

    Churchill, C; Kacprzak, G G; Churchill, Chris; Steidel, Chuck; Kacprzak, Glenn

    2004-01-01

    In this contribution, we review our current knowledge of the properties of galaxies, and their extended halos, selected by MgII absorption in the spectra of background quasars. We then describe recent efforts to quantify the morphologies and orientations of galaxies and explore how these relate to the gas kinematics. In a sample of 26 galaxies, we find no clear connection between the orientation of the quasar line of sight through the galaxy and the velocity spread of the gas. However, it appears that the quantity of gas "stirred up" in the halo may be correlated to asymmetry in the galaxy morphology. Since the galaxies have fairly normal morphologies, this connection may suggest that galaxies with extended halos experienced an interaction or merging event a few dynamical times prior to the epoch of observation.

  2. MAGIICAT I. The MgII Absorber-Galaxy Catalog

    CERN Document Server

    Nielsen, Nikole M; Kacprzak, Glenn G; Murphy, Michael T

    2013-01-01

    We describe the MgII Absorber-Galaxy Catalog, MAGIICAT, a compilation of 182 spectroscopically identified intermediate redshift (0.07 0.3 Angstroms], low redshift (z zmed), where zmed = 0.359 is the median galaxy redshift. We find no differences between the luminosity function subsamples, except for a ~0.5 magnitude dimming with decreasing redshift in the B-band for weak absorbing M_B < -18 galaxies. Rest-frame color B-K correlates with M_K at the 8 sigma level for the whole sample but is driven by the strong absorbing, high redshift subsample (6 sigma). We find possible faint-end "roll offs" in both the B- and K-band luminosity functions. Using M_K as a proxy for stellar mass, we infer that in low stellar mass galaxies, MgII absorption is preferentially detected in blue galaxies and the absorption is more likely to be weak.

  3. MAGIICAT I. THE Mg II ABSORBER-GALAXY CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Nikole M.; Churchill, Christopher W. [New Mexico State University, Las Cruces, NM 88003 (United States); Kacprzak, Glenn G.; Murphy, Michael T., E-mail: nnielsen@nmsu.edu [Swinburne University of Technology, Victoria 3122 (Australia)

    2013-10-20

    We describe the Mg II Absorber-Galaxy Catalog, MAGIICAT, a compilation of 182 spectroscopically identified intermediate redshift (0.07 ≤ z ≤ 1.1) galaxies with measurements of Mg II λλ2796, 2803 absorption from their circumgalactic medium within projected distances of 200 kpc from background quasars. In this work, we present 'isolated' galaxies, which are defined as having no spectroscopically identified galaxy within a projected distance of 100 kpc and a line of sight velocity separation of 500 km s{sup –1}. We standardized all galaxy properties to the ΛCDM cosmology and galaxy luminosities, absolute magnitudes, and rest-frame colors to the B- and K-band on the AB system. We present galaxy properties and rest-frame Mg II equivalent width, W{sub r} (2796), versus galaxy redshift. The well-known anti-correlation between W{sub r} (2796) and quasar-galaxy impact parameter, D, is significant to the 8σ level. The mean color of MAGIICAT galaxies is consistent with an Sbc galaxy for all redshifts. We also present B- and K-band luminosity functions for different W{sub r} (2796) and redshift subsamples: 'weak absorbing' [W{sub r} (2796) < 0.3 Å], 'strong absorbing' [W{sub r} (2796) ≥ 0.3 Å], low redshift (z < (z)), and high redshift (z ≥ (z)), where (z) = 0.359 is the median galaxy redshift. Rest-frame color B – K correlates with M{sub K} at the 8σ level for the whole sample but is driven by the strong absorbing, high-redshift subsample (6σ). Using M{sub K} as a proxy for stellar mass and examining the luminosity functions, we infer that in lower stellar mass galaxies, Mg II absorption is preferentially detected in blue galaxies and the absorption is more likely to be weak.

  4. Modeling the distribution of Mg II absorbers around galaxies using Background Galaxies & Quasars

    CERN Document Server

    Bordoloi, R; Kacprzak, G G; Churchill, C W

    2012-01-01

    We present joint constraints on the distribution of MgII absorption around galaxies, by combining the MgII absorption seen in stacked background galaxy spectra and the distribution of host galaxies of strong MgII systems from the spectra of background quasars. We present a suite of models that predict, the dependence of MgII absorption on a galaxy's apparent inclination, impact parameter(b) and azimuthal angle. The variations in the absorption strength with azimuthal angles provide much stronger constraints on the intrinsic geometry of the MgII absorption than the dependence on the galaxy's inclination. Strong MgII absorbers (W_r(2796)>0.3) are asymmetrically distributed in azimuth around their host galaxies:72% of the absorbers studied and 100% of the close-in absorbers within b<38 kpc, are located within 50deg of the host galaxy's projected minor axis. Composite models consisting either of a simple bipolar component plus a spherical or disk component, or a single highly softened bipolar distribution, can...

  5. Modeling the distribution of Mg II absorbers around galaxies using background galaxies and quasars

    Energy Technology Data Exchange (ETDEWEB)

    Bordoloi, R.; Lilly, S. J. [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich (Switzerland); Kacprzak, G. G. [Swinburne University of Technology, Victoria 3122 (Australia); Churchill, C. W., E-mail: rongmonb@phys.ethz.ch [New Mexico State University, Las Cruces, NM 88003 (United States)

    2014-04-01

    We present joint constraints on the distribution of Mg II absorption around high redshift galaxies obtained by combining two orthogonal probes, the integrated Mg II absorption seen in stacked background galaxy spectra and the distribution of parent galaxies of individual strong Mg II systems as seen in the spectra of background quasars. We present a suite of models that can be used to predict, for different two- and three-dimensional distributions, how the projected Mg II absorption will depend on a galaxy's apparent inclination, the impact parameter b and the azimuthal angle between the projected vector to the line of sight and the projected minor axis. In general, we find that variations in the absorption strength with azimuthal angles provide much stronger constraints on the intrinsic geometry of the Mg II absorption than the dependence on the inclination of the galaxies. In addition to the clear azimuthal dependence in the integrated Mg II absorption that we reported earlier in Bordoloi et al., we show that strong equivalent width Mg II absorbers (W{sub r} (2796) ≥ 0.3 Å) are also asymmetrically distributed in azimuth around their host galaxies: 72% of the absorbers in Kacprzak et al., and 100% of the close-in absorbers within 35 kpc of the center of their host galaxies, are located within 50° of the host galaxy's projected semi minor axis. It is shown that either composite models consisting of a simple bipolar component plus a spherical or disk component, or a single highly softened bipolar distribution, can well represent the azimuthal dependencies observed in both the stacked spectrum and quasar absorption-line data sets within 40 kpc. Simultaneously fitting both data sets, we find that in the composite model the bipolar cone has an opening angle of ∼100° (i.e., confined to within 50° of the disk axis) and contains about two-thirds of the total Mg II absorption in the system. The single softened cone model has an exponential fall off with

  6. K-band Imaging of strong CaII-absorber host galaxies at z~1

    CERN Document Server

    Hewett, Paul

    2007-01-01

    We present K-band imaging of fields around 30 strong CaII absorption line systems, at 0.7galaxies is found within 6"0 (~50kpc) from the absorber line-of-sight. The excess galaxies are preferentially luminous compared to the population of field galaxies. A model in which field galaxies possess a luminosity-dependent cross-section for CaII absorption of the form (L/L*)^0.7 reproduces the observations well. The luminosity-dependent cross-section for the CaII absorbers appears to be significantly stronger than the established (L/L*)^0.4 dependence for MgII absorbers. The associated galaxies lie at large physical distances from the CaII-absorbing gas; we find a mean impact parameter of 24kpc (H0=70km\\s\\Mpc). Combined with the observed number density of CaII absorbers the large physical separations result in an inferred filling factor of only ~10 per cent. The physical origin of the strong CaII absorption remains unclear,...

  7. What Determines the Incidence and Extent of MgII Absorbing Gas Around Galaxies?

    CERN Document Server

    Chen, Hsiao-Wen; Tinker, Jeremy L; Gauthier, Jean-Rene; Helsby, Jennifer E; Shectman, Stephen A; Thompson, Ian B

    2010-01-01

    We study the connections between on-going star formation, galaxy mass, and extended halo gas, in order to distinguish between starburst-driven outflows and infalling clouds that produce the majority of observed MgII absorbers at large galactic radii (>~ 10 h^{-1} kpc) and to gain insights into halo gas contents around galaxies. We present new measurements of total stellar mass (M_star), H-alpha emission line strength (EW(H-alpha)), and specific star formation rate (sSFR) for the 94 galaxies published in H.-W. Chen et al. (2010). We find that the extent of MgII absorbing gas, R_MgII, scales with M_star and sSFR, following R_MgII \\propto M_star^{0.28}\\times sSFR^{0.11}. The strong dependence of R_MgII on M_star is most naturally explained, if more massive galaxies possess more extended halos of cool gas and the observed MgII absorbers arise in infalling clouds which will subsequently fuel star formation in the galaxies. The additional scaling relation of R_MgII with sSFR can be understood either as accounting f...

  8. Phase Structure of Weak MgII Absorbers Star Forming Pockets Outside of Galaxies

    CERN Document Server

    Charlton, J C; Ding, J; Zonak, S G; Bond, N; Rigby, J R; Charlton, Jane C.; Churchill, Christopher W.; Ding, Jie; Zonak, Stephanie; Bond, Nicholas; Rigby, Jane R.

    2001-01-01

    A new and mysterious class of object has been revealed by the detection of numerous weak MgII doublets in quasar absorption line spectra. The properties of these objects will be reviewed. They are not in close proximity to luminous galaxies, yet they have metallicities close to the solar value; they are likely to be self-enriched. A significant fraction of the weak MgII absorbers are constrained to be less than 10 parsecs in size, yet they present a large cross-section for absorption, indicating that there are more than a million times more of them than there are luminous galaxies. They could be remnants of Population III star clusters or tracers of supernova remnants in a population of "failed dwarf galaxies" expected in cold dark matter structure formation scenarios.

  9. Galaxy counterparts of intervening high-z sub-DLAs/DLAs and MgII absorbers towards gamma-ray bursts

    CERN Document Server

    Schulze, S; Milvang-Jensen, B; Rossi, A; Jakobsson, P; Ledoux, C; De Cia, A; Kruehler, T; Mehner, A; Bjoernsson, G; Chen, H -W; Vreeswijk, P M; Perley, D A; Hjorth, J; Levan, A J; Tanvir, N R; Ellison, S; Moller, P; Worseck, G; Chapman, R; Dall'Aglio, A; Letawe, G

    2012-01-01

    We present the first search for galaxy counterparts of intervening high-z (2galaxy counterparts of the absorbers we use deep optical and near-infrared imaging, and low-, mid- and high-resolution spectroscopy acquired with 6 to 10-m class telescopes, the Hubble and the Spitzer space telescopes. Furthermore, we use the spectroscopic information and spectral-energy-distribution fitting techniques to study them in detail. Our main result is the detection and spectroscopic confirmation of the galaxy counterpart of the intervening DLA at z=3.096 in the field of GRB 070721B (z_GRB=3.6298) as proposed by other authors. We also identify good candidates for the galaxy counterparts of the two strong MgII absorbers at z=0.6915 and 1.4288 towards GRB 050820A (z_GRB=2.615). The properties of the detected DLA galaxy are typical for Lyman-break galaxies (LBGs) at similar re...

  10. Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert Galaxies: II. Warm Absorber dynamics and feedback to galaxies

    CERN Document Server

    Laha, Sibasish; Chakravorty, Susmita; Dewangan, Gulab C; Kembhavi, Ajit K

    2016-01-01

    This paper is a sequel to the extensive study of warm absorber (WA) in X-rays carried out using high resolution grating spectral data from XMM-Newton satellite (WAX-I). Here we discuss the global dynamical properties as well as the energetics of the WA components detected in the WAX sample. The slope of WA density profile ($n\\propto r^{-\\alpha}$) estimated from the linear regression slope of ionization parameter $\\xi$ and column density $N_H$ in the WAX sample is $\\alpha=1.236\\pm 0.034$. We find that the WA clouds possibly originate as a result of photo-ionised evaporation from the inner edge of the torus (torus wind). They can also originate in the cooling front of the shock generated by faster accretion disk outflows, the ultra-fast outflows (UFO), impinging onto the interstellar medium or the torus. The acceleration mechanism for the WA is complex and neither radiatively driven wind nor MHD driven wind scenario alone can describe the outflow acceleration. However, we find that radiative forces play a signi...

  11. Simultaneous Ultraviolet and X-ray Observations of the Seyfert Galaxy NGC 4151. II. Physical Conditions in the UV Absorbers

    CERN Document Server

    Krämer, S B; Gabel, J R; Kriss, G A; Netzer, H; Peterson, B M; George, I M; Gull, T R; Hutchings, J B; Mushotzky, R F; Turner, T J

    2006-01-01

    We present a detailed analysis of the intrinsic absorption in the Seyfert 1 galaxy NGC 4151 using UV spectra from the HST/STIS and FUSE, obtained 2002 May as part of a set of contemporaneous observations that included Chandra/HETGS spectra. In our analysis of the Chandra spectra, we determined that the soft X-ray absorber was the source of the saturated UV lines of O VI, C IV, and N V associated with the absorption feature at a radial velocity of ~ -500 km/sec, which we referred to as component D+E. In the present work, we have derived tighter constrains on the the line-of-sight covering factors, densities, and radial distances of the absorbers. We find that the Equivalent Widths (EWs) of the low-ionization lines associated with D+E varied over the period from 1999 July to 2002 May. The drop in the EWs of these lines between 2001 April and 2002 May are suggestive of bulk motion of gas out of our line-of-sight. If these lines from these two epochs arose in the same sub-component, the transverse velocity of the...

  12. Galaxy Clusters in the Line of Sight to Background Quasars: I. Survey Design and Incidence of MgII Absorbers at Cluster Redshifts

    CERN Document Server

    López, S; Lira, P; Padilla, N; Gilbank, D G; Gladders, M D; Maza, J; Tejos, N; Vidal, M; Yee, H K C

    2008-01-01

    We describe the first optical survey of absorption systems associated with galaxy clusters at z= 0.3-0.9. We have cross-correlated SDSS DR3 quasars with high-redshift cluster/group candidates from the Red-Sequence Cluster Survey. We have found 442 quasar-cluster pairs for which the MgII doublet might be detected at a transverse (physical) distance d2.0 Ang.) near cluster redshifts shows a significant (>3 sigma) overabundance (up to a factor of 15) when compared with the 'field' population; (2) the overabundance is more evident at smaller distances (d<1 Mpc) than larger distances (d<2 Mpc) from the cluster center; and, (3) the population of weak MgII systems (W_0<0.3 Ang.) near cluster redshifts conform to the field statistics. Unlike in the field, this dichotomy makes n(W) in clusters appear flat and well fitted by a power-law in the entire W-range. A sub-sample of the most massive clusters yields a stronger and still significant signal. Since either the absorber number density or filling-factor/cros...

  13. MgII Absorption through Intermediate Redshift Galaxies

    CERN Document Server

    Churchill, C W; Steidel, C C; Churchill, Christopher W.; Kacprzak, Glenn G.; Steidel, Charles C.

    2005-01-01

    The current status and remaining questions of MgII absorbers are reviewed with an eye toward new results incorporating high quality Hubble Space Telescope images of the absorbing galaxies. In the end, we find that our current picture of extended gaseous regions around galaxies at earlier epochs is in need of some revision; MgII absorbing "halos" appear to be patchier and their geometry less regular than previously inferred. We also find that the so-called "weak" MgII absorbers are associated with normal galaxies over a wide range of impact parameters, suggesting that this class of absorber does not strictly select low surface brightness, dwarf galaxies, or IGM material. We emphasize the need for a complete survey of the galaxies in quasar fields, and the importance of obtaining rotation curves of confirmed absorbing galaxies.

  14. A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: II. Program Design, Absorption-line Measurements, and Absorber Statistics

    CERN Document Server

    Burchett, Joseph N; Prochaska, J Xavier; Werk, Jessica K; Tumlinson, Jason; O'Meara, John M; Bordoloi, Rongmon; Katz, Neal; Willmer, C N A

    2015-01-01

    To investigate the evolution of metal-enriched gas over recent cosmic epochs as well as to characterize the diffuse, ionized, metal-enriched circumgalactic medium (CGM), we have conducted a blind survey for C IV absorption systems in 89 QSO sightlines observed with the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS). We have identified 42 absorbers at z < 0.16, comprising the largest uniform blind sample size to date in this redshift range. Our measurements indicate an increasing C IV absorber number density per comoving path length (dN/dX = 7.5 +/- 1.1) and modestly increasing mass density relative to the critical density of the Universe (Omega(C IV) = 10.0 +/- 1.5 x 10^-8 ) from z ~ 1.5 to the present epoch, consistent with predictions from cosmological hydrodynamical simulations. Furthermore, the data support a functional form for the column density distribution function that deviates from a single power-law, also consistent with independent theoretical predictions. As the data also probe...

  15. Galaxy counterparts of metal-rich damped Lyα absorbers: II. A solar-metallicity and dusty DLA at zabs= 2.58

    NARCIS (Netherlands)

    Fynbo, J.P.U.; Ledoux, C.; Noterdaeme, P.; Christensen, L.; Møller, P.; Durgapal, A.K.; Goldoni, P.; Kaper, L.; Krogager, J. -K; Laursen, P.; Maund, J.R.; Milvang-Jensen, B.; Okoshi, K.; Rasmussen, P.K.; Thorsen, T. J.; Toft, S.; Zafar, T.

    2011-01-01

    This is the second paper of a series reporting on the results from a survey conducted with the ESO VLT/X-shooter spectrograph. We target high-metallicity damped Lyman α absorbers (DLAs) with the aim of investigating the relation between galaxies detected in emission and those detected in absorption.

  16. Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert Galaxies - II. Warm absorber dynamics and feedback to galaxies

    Science.gov (United States)

    Laha, Sibasish; Guainazzi, Matteo; Chakravorty, Susmita; Dewangan, Gulab C.; Kembhavi, Ajit K.

    2016-04-01

    This paper is a sequel to the extensive study of warm absorber (WA) in X-rays carried out using high-resolution grating spectral data from XMM-Newton satellite (WAX-I). Here we discuss the global dynamical properties as well as the energetics of the WA components detected in the WAX sample. The slope of WA density profile (n ∝ r-α) estimated from the linear regression slope of ionization parameter ξ and column density NH in the WAX sample is α = 1.236 ± 0.034. We find that the WA clouds possibly originate as a result of photoionized evaporation from the inner edge of the torus (torus wind). They can also originate in the cooling front of the shock generated by faster accretion disc outflows, the ultrafast outflows, impinging on to the interstellar medium or the torus. The acceleration mechanism for the WA is complex and neither radiatively driven wind nor MHD-driven wind scenario alone can describe the outflow acceleration. However, we find that radiative forces play a significant role in accelerating the WA through the soft X-ray absorption lines, and also with dust opacity. Given the large uncertainties in the distance and volume filling factor estimates of the WA, we conclude that the kinetic luminosity ĖK of WA may sometimes be large enough to yield significant feedback to the host galaxy. We find that the lowest ionization states carry the maximum mass outflow, and the sources with higher Fe M UTA absorption (15-17 Å) have more mass outflow rates.

  17. Galaxy S II

    CERN Document Server

    Gralla, Preston

    2011-01-01

    Unlock the potential of Samsung's outstanding smartphone with this jargon-free guide from technology guru Preston Gralla. You'll quickly learn how to shoot high-res photos and HD video, keep your schedule, stay in touch, and enjoy your favorite media. Every page is packed with illustrations and valuable advice to help you get the most from the smartest phone in town. The important stuff you need to know: Get dialed in. Learn your way around the Galaxy S II's calling and texting features.Go online. Browse the Web, manage email, and download apps with Galaxy S II's 3G/4G network (or create you

  18. MAGIICAT II. General Characteristics of the MgII Absorbing Circumgalactic Medium

    CERN Document Server

    Nielsen, Nikole M; Kacprzak, Glenn G

    2012-01-01

    We fully characterize the MgII absorbing circumgalactic medium (CGM) using the "MgII Absorber-Galaxy Catalog" (MAGIICAT), a compilation comprising 169 intermediate redshift (0.1 < z < 1.1) galaxies within 200 kpc (projected) of background quasars. We examine the rest-frame equivalent widths, Wr(2796), and covering fractions, f_c, down to Wr(2796) ~ 0.003 Angstroms, against galaxy redshift, B- and K-band luminosity, B-K color, and impact parameter, D. We also present B- and K-band luminosity functions for different Wr(2796) and redshift regimes. The radial extent of the MgII absorbing CGM, R(L)=R*(L/L*)^beta, exhibits little dependency on Wr(2796) threshold in the B-band, but becomes less sensitive to luminosity in the K-band. In both the B- and K-bands, R(L) has a much steeper luminosity dependence for bluer galaxies than for redder galaxies, and for lower redshift galaxies compared to higher redshift galaxies. The covering fractions exhibit clear differential dependencies on Wr(2796) threshold, galaxy ...

  19. MAGIICAT II. GENERAL CHARACTERISTICS OF THE Mg II ABSORBING CIRCUMGALACTIC MEDIUM

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Nikole M.; Churchill, Christopher W. [New Mexico State University, Las Cruces, NM 88003 (United States); Kacprzak, Glenn G., E-mail: nnielsen@nmsu.edu, E-mail: cwc@nmsu.edu, E-mail: gkacprzak@astro.swin.edu.au [Swinburne University of Technology, Victoria 3122 (Australia)

    2013-10-20

    We examine the Mg II absorbing circumgalactic medium (CGM) for the 182 intermediate redshift (0.072 ≤ z ≤ 1.120) galaxies in the 'Mg II Absorber-Galaxy Catalog' (MAGIICAT). We parameterize the anti-correlation between equivalent width, W{sub r} (2796), and impact parameter, D, with a log-linear fit, and show that a power law poorly describes the data. We find that higher luminosity galaxies have larger W{sub r} (2796) at larger D (4.3σ). The covering fractions, f{sub c} , decrease with increasing D and W{sub r} (2796) detection threshold. Higher luminosity galaxies have larger f{sub c} ; no absorption is detected in lower luminosity galaxies beyond 100 kpc. Bluer and redder galaxies have similar f{sub c} for D < 100 kpc, but for D > 100 kpc, bluer galaxies have larger f{sub c} , as do higher redshift galaxies. The 'absorption radius', R(L) = R{sub *}(L/L*){sup β}, which we examine for four different W{sub r} (2796) detection thresholds, is more luminosity sensitive to the B-band than the K-band, more sensitive for redder galaxies than for bluer galaxies, and does not evolve with redshift for the K-band, but becomes more luminosity sensitive toward lower redshift for the B-band. These trends clearly indicate a more extended Mg II absorbing CGM around higher luminosity, bluer, and higher redshift galaxies. Several of our findings are in conflict with other works. We address these conflicts and discuss the implications of our results for the low-ionization, intermediate redshift CGM.

  20. The Absorption Signatures of Dwarf Galaxies: The z=1.04 Multicloud Weak MgII Absorber toward PG 1634+706

    CERN Document Server

    Zonak, S G; Ding, J; Churchill, C W; Zonak, Stephanie G.; Charlton, Jane C.; Ding, Jie; Churchill, Christopher W.

    2004-01-01

    We analyze high resolution spectra of a multi--cloud weak [defined as W_r(MgII) < 0.3 A] absorbing system along the line of sight to PG 1634+706. This system gives rise to a partial Lyman limit break and absorption in MgII, SiII, CII, SiIII, SiIV, CIV, and OVI. The lower ionization transitions arise in two kinematic subsystems with a separation of ~150 km/s. Each subsystem is resolved into several narrow components, having Doppler widths of 3-10 kms. For both subsystems, the OVI absorption arises in a separate higher ionization phase, in regions dominated by bulk motions in the range of 30-40 km/s. The two OVI absorption profiles are kinematically offset by ~50 km/s with respect to each of the two lower ionization subsystem. In the stronger subsystem, the SiIII absorption is strong with a distinctive, smooth profile shape and may partially arise in shock heated gas. Moreover, the kinematic substructure of SiIV traces that of the lower ionization MgII, but may be offset by ~3 km/s. Based upon photoionizatio...

  1. The Kinematic Evolution of Strong MgII Absorbers

    CERN Document Server

    Mshar, Andrew C; Lynch, Ryan S; Churchill, Chris; Kim, Tae-Sun

    2007-01-01

    We consider the evolution of strong (W_r(2796) > 0.3A) MgII absorbers, most of which are closely related to luminous galaxies. Using 20 high resolution quasar spectra from the VLT/UVES public archive, we examine 33 strong MgII absorbers in the redshift range 0.3 < z < 2.5. We compare and supplement this sample with 23 strong MgII absorbers at 0.4 < z < 1.4 observed previously with HIRES/Keck. We find that neither equivalent width nor kinematic spread (the optical depth weighted second moment of velocity) of MgII2796 evolve. However, the kinematic spread is sensitive to the highest velocity component, and therefore not as sensitive to additional weak components at intermediate velocities relative to the profile center. The fraction of absorbing pixels within the full velocity range of the system does show a trend of decreasing with decreasing redshift. Most high redshift systems (14/20) exhibit absorption over the entire system velocity range, which differs from the result for low redshift systems ...

  2. The Kinematic Connection Between QSO-Absorbing Gas and Galaxies at Intermediate Redshift

    CERN Document Server

    Steidel, C C; Shapley, A E; Churchill, C W; Dickinson, M; Pettini, M

    2002-01-01

    We present complementary data on 5 intermediate redshift (0.44 < z < 0.66) MgII absorbing galaxies, combining high spatial resolution imaging from HST, high--resolution QSO spectroscopy from Keck/HIRES, and galaxy kinematics from intermediate resolution spectroscopy using Keck/LRIS. These data allow a direct comparison of the kinematics of gas at large galactocentric impact parameters with the galaxy kinematics obtained from the faint galaxy spectroscopy. All 5 galaxies appear to be relatively normal spirals, with measured rotation curves yielding circular velocities in the range 100 < v_c < 260 km/s. We find that in 4 of the 5 cases examined, the velocities of all of the Mg II absorption components lie entirely to one side of the galaxy systemic redshift. These observations are consistent with rotation being dominant for the absorbing gas kinematics; however, the total range of velocities observed is inconsistent with simple disk rotation in every case. Simple kinematic models that simultaneously...

  3. Mg II & C IV Kinematics vs. Stellar Kinematics in Galaxies

    CERN Document Server

    Churchill, C W; Churchill, Chris; Steidel, Chuck

    2002-01-01

    Comparisons of the kinematics of Mg II absorbing gas and the stellar rotation curves in 0.5 < z < 1.0 spiral galaxies suggests that, at least in some cases, the extended gaseous envelopes may be dynamically coupled to the stellar matter. A strong correlation exists between the overall kinematic spread of Mg II absorbing gas and C IV absorption strength, and therefore kinematics of the higher-ionization gas. Taken together, the data may suggest a "halo/disk connection" between z~1 galaxies and their extended gaseous envelopes. Though the number of galaxies in our sample are few, there are no clear examples that suggest the gas is accreting/infalling isotropically about the galaxies from the intergalactic medium.

  4. High-Redshift Superwinds as the Source of the Strongest Mg II Absorbers A Feasibility Analysis

    CERN Document Server

    Bond, N A; Charlton, J C; Vogt, S S

    2001-01-01

    We present HIRES/Keck profiles of four extremely strong (W_r > 1.8 A) Mg II absorbers at 1 1.8 A evolve away from z = 2 to the present. We propose that a substantial fraction of these very strong absorbers are due to superwinds and that their evolution is related to the redshift evolution of star-forming galaxies. Based on the observed redshift number density of W_r > 1.8 A Mg II absorbers at 1 < z < 2, we explore whether it is realistic that superwinds from starbursting galaxies could give rise to these absorbers. Finally, we do an analysis of the superwind connection to damped Lya absorbers (DLAs). DLAs and superwinds evolve differently and usually have different kinematic structure, indicating that superwinds probably do not give rise to the majority of DLAs.

  5. The Environments of Ultra-strong Mg II Absorbers

    CERN Document Server

    Nestor, D B; Rao, S M; Quider, A M; Nestor, Daniel B.; Turnshek, David A.; Rao, Sandhya M.; Quider, Anna M.

    2006-01-01

    We present r'- or i'-band WIYN images of the fields of 15 Sloan Digital Sky Survey quasars that have spectra exhibiting intervening MgII absorption-line systems with rest equivalent widths 2.7A \\le REW \\le 6.0A and redshifts 0.42 < z_{abs} < 0.84. Such systems are rare and exhibit projected absorption velocity spreads in excess of \\approx 300-650 km/s. Approximately 60% are expected to be damped Ly\\alpha systems. In each of our fields we detect at least one galaxy that, if at the absorption redshift, would have impact parameter b \\lesssim 40 kpc and luminosity L \\gtrsim 0.3 L*. We measure a significant excess of galaxies at low-b to the sightlines over a large range of luminosity. Many of the sightlines are found to pass either through or close to the optically-luminous extent of a galaxy. Considering the very large velocity spreads seen in absorption, this suggests that these absorbing regions are more kinematically complex than local spirals such as the Milky Way. Our data indicate that interactions a...

  6. Galaxy counterparts of metal-rich damped Lyman-alpha absorbers - II. A solar-metallicity, molecular-rich, and dusty DLA at z_abs=2.58

    CERN Document Server

    Fynbo, J P U; Noterdaeme, P; Christensen, L; Moller, P; Durgapal, A K; Goldoni, P; Kaper, L; Krogager, J -K; Laursen, P; Maund, J R; Milvang-Jensen, B; Okoshi, K; Rasmussen, P K; Thorsen, T J; Toft, S; Zafar, T

    2010-01-01

    [Abridged]. Here, we report on the discovery of the galaxy counterpart of the z_abs=2.58 DLA on the line-of-sight to the z=3.07 quasar SDSS J091826.16+163609.0. The galaxy counterpart of the DLA is detected in the OIII 5007 and OII 3726,3729 emission lines redshifted into the NIR at an impact parameter of 16 kpc. Ly-alpha emission is not detected. The upper limit implies that Ly-alpha emission from this galaxy is suppressed by more than an order of magnitude. The DLA is amongst the most metal-rich DLAs studied so far at comparable redshifts. We find evidence for substantial depletion of refractory elements onto dust grains. Fitting the main metal line component of the DLA, which is located at z_abs=2.5832 and accounts for at least 85% of the total column density of low-ionisation species, we measure metal abundances from ZnII, SII, SiII, CrII, MnII, FeII and NiII of -0.12, -0.26, -0.46, -0.88, -0.92, -1.03 and -0.78, respectively. In addition, we detect absorption in the Lyman and Werner bands of hydrogen, wh...

  7. The Population of Weak MgII Absorbers. II The Properties of Single-Cloud Systems

    CERN Document Server

    Rigby, J R; Churchill, C W; Rigby, Jane R.; Charlton, Jane C.; Churchill, Christopher W.

    2001-01-01

    We present an investigation of MgII absorbers characterized as single-cloud weak systems at z~1. We measured column densities and Doppler parameters for MgII and FeII in 15 systems found in HIRES/Keck spectra at 6.6 km/s. Using these quantities and CIV, Lyman alpha and Lyman limit absorption observed with FOS/HST (resolution ~230 km/s) we applied photoionization models to each system to constrain metallicities, densities, ionization conditions, and sizes. We find that: (1) Single-cloud weak systems are optically thin in neutral hydrogen and may have their origins in a population of objects distinct from the optically thick strong MgII absorbers, which are associated with bright galaxies. (2) Weak systems account for somewhere between 25% to 100% of the z < 1 Lyman alpha forest clouds in the range 15.8II absorber that we term ``iron-rich''. These clo...

  8. An extended cold gas absorber in a central cluster galaxy

    Science.gov (United States)

    Smith, Russell J.; Edge, Alastair C.

    2017-10-01

    We present the serendipitous discovery of an extended cold gas structure projected close to the brightest cluster galaxy (BCG) of the z=0.045 cluster Abell 3716, from archival integral field spectroscopy. The gas is revealed through narrow Na D line absorption, seen against the stellar light of the BCG, which can be traced for $\\sim$25 kpc, with a width of 2-4 kpc. The gas is offset to higher velocity than the BCG (by $\\sim$100 km/s), showing that it is infalling rather than outflowing; the intrinsic linewidth is $\\sim$80 km/s (FWHM). Very weak H$\\alpha$ line emission is detected from the structure, and a weak dust absorption feature is suggested from optical imaging, but no stellar counterpart has been identified. We discuss some possible interpretations for the absorber: as a projected low-surface-brightness galaxy, as a stream of gas that was stripped from an infalling cluster galaxy, or as a "retired" cool-core nebula filament.

  9. A survey of weak MgII absorbers at redshift =1.78

    CERN Document Server

    Lynch, R S; Kim, T S; Lynch, Ryan S.; Charlton, Jane C.; Kim, Tae-Sun

    2006-01-01

    The exact nature of weak MgII absorbers (those with W_r(2796) < 0.3 A) is a matter of debate, but most are likely related to areas of local star formation or supernovae activity outside of giant galaxies. Using 18 QSO spectra obtained with the Ultra-Violet Echelle Spectrograph (UVES) on the Very Large Telescope (VLT), we have conducted a survey for weak MgII absorbers at 1.4 < z < 2.4. We searched a redshift path length of 8.51, eliminating regions badly contaminated by atmospheric absorption so that the survey is close to 100% complete to W_r(2796) = 0.02 A. We found a total of 9 weak absorbers, yielding a number density of absorbers of dN/dz = 1.06 +/- 0.12 for 0.02 <= W_r(2796) < 0.3 A. Narayanan et al. (2005) found dN/dz = 1.00 +/- 0.20 at 0 < z < 0.3 and Churchill et al. (1999) found dN/dz = 1.74 +/- 0.10 at 0.4 < z < 1.4. Therefore, the population of weak MgII absorbers appears to peak at z~1. We explore the expected evolution of the absorber population subject to a changing e...

  10. Nature of the absorbing gas associated with a galaxy group at z˜0.4

    Science.gov (United States)

    Péroux, Céline; Rahmani, Hadi; Quiret, Samuel; Pettini, Max; Kulkarni, Varsha; York, Donald G.; Straka, Lorrie; Husemann, Bernd; Milliard, Bruno

    2017-01-01

    We present new Multi Unit Spectroscopic Explorer observations of quasar field Q2131-1207 with a log N(H I} = 19.50 ± 0.15 sub-damped Lyman α at zabs = 0.42980. We detect four galaxies at a redshift consistent with that of the absorber where only one was known before this study. Two of these are star-forming galaxies, while the ones further away from the quasar (>140 kpc) are passive galaxies. We report the metallicities of the H II regions of the closest objects (12 + log(O/H) = 8.98 ± 0.02 and 8.32 ± 0.16) to be higher or equivalent within the errors to the metallicity measured in absorption in the neutral phase of the gas (8.15 ± 0.20). For the closest object, a detailed morphokinematic analysis indicates that it is an inclined large rotating disc with Vmax = 200 ± 3 km s-1. We measure the masses to be Mdyn = 7.4 ± 0.4 × 1010 M⊙ and Mhalo = 2.9 ± 0.2 × 1012 M⊙. Some of the gas seen in absorption is likely to be corotating with the halo of that object, possibly due to a warped disc. The azimuthal angle between the quasar line-of-sight and the projected major axis of the galaxy on the sky is 12° ± 1° which indicates that some other fraction of the absorbing gas might be associated with accreting gas. This is further supported by the galaxy to gas metallicity difference. Based on the same arguments, we exclude outflows as a possibility to explain the gas in absorption. The four galaxies form a large structure (at least 200 kpc wide) consistent with a filament or a galaxy group so that a fraction of the absorption could be related to intragroup gas.

  11. Ca II Absorbers in the Sloan Digital Sky Survey: Statistics

    CERN Document Server

    Sardane, Gendith M; Rao, Sandhya M

    2014-01-01

    We present the results of a survey for CaII 3934,3969 absorption-line systems culled from ~ 95,000 Sloan Digital Sky Survey (SDSS) Data Release 7 and Data Release 9 quasar spectra. With 435 doublets identified in the catalog, this list is the largest CaII catalog compiled to date, spanning redshifts z = 0.3 A, is n_0=0.017 +/- 0.001. In comparison to MgII surveys, we found that only 3% of MgII systems in the SDSS have CaII, confirming that it is rare to identify CaII in quasar absorption-line surveys. We also report on some preliminary investigations of the nature of the two populations of CaII absorbers, and show that they can likely be distinguished using their MgII properties.

  12. Measuring the Halo Mass of z=3 Damped Ly-alpha Absorbers from the Absorber-Galaxy Cross-correlation

    CERN Document Server

    Bouche, N; Weinberg, D H; Katz, N; Davé, R; Lowenthal, J D; Bouche, Nicolas; Gardner, Jeffrey P.; Weinberg, David H.; Katz, Neal; Dave, Romeel; Lowenthal, James D.

    2005-01-01

    [Abridged] We test the reliability of a method to measure the mean halo mass of Damped Ly-alpha absorbers (DLAs). The method is based on measuring the ratio of the cross-correlation between DLAs and galaxies to the auto-correlation of the galaxies themselves ($w_{\\rm dg}/w_{\\rm gg}$), which is (in linear theory) the ratio of their bias factor. This is shown to be true irrespective of the galaxy redshift distribution, provided that one uses the same galaxies for the two correlation functions. The method is applicable to all redshifts. Here, we focus on z=3 DLAs and we demonstrate that the method robustly constrains the mean DLA halo mass using smoothed particle hydrodynamics (SPH) cosmological simulations. If we use the bias formalism of Mo & White (2002) with the DLA and galaxy mass distributions of these simulations, we predict a bias ratio of 0.771. Direct measurement from the simulations of $w_{\\rm dg}/w_{\\rm gg}$ st yields a ratio of 0.73+/-0.08, in excellent agreement with that prediction. Equivalent...

  13. Clustering of Mg II absorption line systems around massive galaxies: an important constraint on feedback processes in galaxy formation

    Science.gov (United States)

    Kauffmann, Guinevere; Nelson, Dylan; Ménard, Brice; Zhu, Guangtun

    2017-07-01

    We use the latest version of the metal line absorption catalogue of Zhu & Ménard to study the clustering of Mg II absorbers around massive galaxies (˜1011.5 M⊙), quasars and radio-loud active galactic nuclei (AGNs) with redshifts between 0.4 and 0.75. Clustering is evaluated in two dimensions by binning absorbers both in the projected radius and velocity separation. Excess Mg II is detected around massive galaxies out to Rp = 20 Mpc. At projected radii less than 800 kpc, the excess extends out to velocity separations of 10 000 km s-1. The extent of the high-velocity tail within this radius is independent of the mean stellar age of the galaxy and whether or not it harbours an AGN. We interpret our results using the publicly available Illustris and Millennium simulations. Models where the Mg II absorbers trace the dark matter particle or subhalo distributions do not fit the data. They overpredict the clustering on small scales and do not reproduce the excess high velocity separation Mg II absorbers seen within the virial radius of the halo. The Illustris simulations that include thermal, but not mechanical feedback from AGNs, also do not provide an adequate fit to the properties of the cool halo gas within the virial radius. We propose that the large velocity separation Mg II absorbers trace gas that has been pushed out of the dark matter haloes, possibly by multiple episodes of AGN-driven mechanical feedback acting over long time-scales.

  14. The Cross-correlation of MgII Absorption and Galaxies in BOSS

    CERN Document Server

    Pérez-Ràfols, Ignasi; Lundgren, Britt; Ge, Jian; Petitjean, Patrick; Schneider, Donald P; York, Donald G; Weaver, Benjamin A

    2014-01-01

    We present a measurement of the cross-correlation of MgII absorption and massive galaxies, using the DR11 galaxy sample of the Baryon Oscillation Spectroscopic Survey of SDSS-III, and the DR7 quasar spectra of SDSS-II. The cross-correlation is measured by stacking quasar absorption spectra shifted to the redshift of galaxies that are within a certain impact parameter bin of the quasar, after dividing by a quasar continuum model. This results in an average MgII equivalent width as a function of impact parameter from a galaxy, ranging from 50 kpc to more than 10 Mpc in proper units, which includes all MgII absorbers. We show that special care needs to be taken to use an unbiased quasar continuum estimator, to avoid systematic errors in the measurement of the mean stacked MgII equivalent width. The measured cross-correlation follows the expected shape of the galaxy correlation function, although measurement errors are large. We use the cross-correlation amplitude to derive the bias factor of MgII absorbers, find...

  15. Catalog of strong MgII absorbers (Lawther+, 2012)

    DEFF Research Database (Denmark)

    Lawther, D.; Paarup, Troels; Schmidt, Morten L.

    2012-01-01

    of our paper. A subset of the absorbers have been visually inspected - see the MAN_OK flag in the catalog. The number of sightlines searched, tabulated by absorber redshift, i.e. g(z), is available as an ASCII table (for S/N>8 and S/N>15). All analysis in our paper is based on the SNR>8 coverage......Here we present a catalog of strong (rest equivalent width Wr> intervening Mg II absorbers in the SDSS Data Release 7 quasar catalog (2010AJ....139.2360S, Cat. VII/260). The intervening absorbers were found by a semi-automatic algorithm written in IDL - for details of the algorithm see section 2...

  16. The Contribution of HI-Rich Galaxies to the Damped Absorber Population at z=0

    CERN Document Server

    Rosenberg, J L; Rosenberg, Jessica L.; Schneider, Stephen E.

    2001-01-01

    We present a study of HI-rich galaxies in the local universe selected from blind emission-line surveys. These galaxies represent the emission-line counterparts of local damped Lyman-alpha systems. We find that the HI cross-section of galaxies is drawn from a large range of galaxy masses below M_star, 66% of the area comes from galaxies in the range 8.5 < Log M_star < 9.7. Both because of the low mass galaxy contribution, and because of the range of galaxy types and luminosities at any given HI mass, the galaxies contributing to the HI cross-section are not exclusively L_star spirals, as is often expected. The optical and near infrared counterparts of these galaxies cover a range of types (from spirals to irregulars), luminosities (from L_star to <0.01 L_star), and surface brightnesses. The range of optical and near infrared properties as well as the kinematics for this population are consistent with the properties for the low-z damped Lyman-alpha absorbers. We also show that the number of HI-rich gal...

  17. A Correlation Between Galaxy Morphology and MgII Halo Absorption Strength

    CERN Document Server

    Kacprzak, G G; Steidel, C C; Murphy, M T; Evans, J L; Kacprzak, Glenn G.; Churchill, Christopher W.; Steidel, Charles C.; Murphy, Michael T.; Evans, Jessica L.

    2007-01-01

    (Abridged) We compared the quantified morphological properties of 37 intermediate redshift MgII absorption selected galaxies to the properties of the absorbing halo gas, observed in the spectra of background quasars. The galaxy morphologies were measured using GIM2D modeling of Hubble Space Telescope WFPC-2 images and the absorbing gas properties were obtained from HIRES/Keck and UVES/VLT quasar spectra. We found a 3.1 sigma correlation between galaxy morphological asymmetries normalized by the quasar-galaxy projected separations, A/D, and the MgII rest-frame equivalent widths. Saturation effects cause increased scatter in the relationship with increasing W_r(2796). We defined a subsample for which the fraction of saturated pixels in the absorption profiles is f_sat<0.5. The correlation strengthened to 3.3 sigma. We also find a paucity of small morphological asymmetries for galaxies selected by MgII absorption as compared to those of the general population of field galaxies, as measured in the Medium Deep ...

  18. Mg II Absorber Number Density at z~0.05 Implications for Omega_DLA Evolution

    CERN Document Server

    Churchill, C W

    2001-01-01

    [Abridged] A 147 quasar/AGN spectra, obtained with FOS/HST, have been searched for Mg II absorbers for 0 = 0.06, yielding dN/dz = 0.22(+0.12)(-0.09) for absorbers with W_r > 0.6 Ang. This is consistent with the value expected if these systems do not evolve from higher redshifts (z = 2.2). (2) No systems with W_r 0.2 galaxies. (3) Three systems are candidates for damped Lyman-alpha absorbers (DLAs). Based upon the results of Rao & Turnshek (2000, ApJS, 130, 1), this translates to dN/dz = 0.08(+0.09)(-0.05) for DLAs at z ~ 0. This would suggest that dN/dz for DLAs does not evolve from z = 4 to z = 0. However, because of the distribution of H I mass in 21-cm selected galaxies, the Rao & Turnshek finding that the cosmological H I mass density, Omega_DLA, decreases either rapidly from z = 0.5 to z = 0, or more gradually from z = 1.5, still holds.

  19. The MUSE QSO Blind Survey: A Census of Absorber Host Galaxies

    Science.gov (United States)

    Straka, Lorrie A.; MUSE GTO Consortium

    2017-03-01

    Understanding the distribution of gas in galaxies and its interaction with the IGM is crucial to complete the picture of galaxy evolution. At all redshifts, absorption features seen in QSO spectra serve as a unique probe of the gaseous content of foreground galaxies and the IGM, extending out to 200 kpc. Studies show that star formation history is intimately related to the co-evolution of galaxies and the IGM. In order to study the environments traced by absorption systems and the role of inflows and outflows, it is critical to measure the emission properties of host galaxies and their halos. We overcome the challenge of detecting absorption host galaxies with the MUSE integral field spectrograph on VLT. MUSE's large field of view and sensitivity to emission lines has allowed a never-before seen match between the number density of absorbers along QSO sightlines and the number density of emission line galaxies within 200 kpc of the QSO. These galaxies represent a sample for which previously elusive connections can be made between mass, metallicity, SFR, and absorption.

  20. Halo Gas Cross Sections And Covering Fractions of MgII Absorption Selected Galaxies

    CERN Document Server

    Kacprzak, G G; Steidel, C C; Murphy, M T

    2007-01-01

    We examine halo gas cross sections and covering fractions, f_c, of intermediate redshift MgII absorption selected galaxies. We computed statistical absorber halo radii, R_x, using current values of dN/dz and Schechter luminosity function parameters, and have compared these values to the distribution of impact parameters and luminosities from a sample of 37 galaxies. For equivalent widths W_r(2796) > 0.3 Ang, we find 43 R_x and several non-absorbing galaxies lie at D ~ 0.6 for our sample. Moreover, the data suggest halo radii of MgII absorbing galaxies do not follow a luminosity scaling with beta in the range of 0.2-0.28, if f_c= 1 as previously reported. However, provided f_c~0.6, we find that halo radii can remain consistent with a Holmberg-like luminosity relation with beta > 0.2 and R* = R_x/sqrt(f_c)= 110 kpc. No luminosity scaling (beta=0) is also consistent with the observed distribution of impact parameters if f_c < 0.37. The data support a scenario in which gaseous halos are patchy and likely hav...

  1. Faraday Rotation from Magnesium II Absorbers towards Polarized Background Radio Sources

    CERN Document Server

    Farnes, J S; Corrigan, M E; Gaensler, B M

    2014-01-01

    Strong magnesium II (MgII) absorption lines in quasar spectra typically serve as a proxy for an intervening galaxy along the line of sight. Previous studies have found a correlation between the number of these MgII absorbers and the rotation measure (RM) at $\\approx5$ GHz. We cross-match a sample of 35,752 optically-identified non-intrinsic MgII absorption systems with 25,649 polarized background radio sources for which we have measurements of both the spectral index and RM at 1.4 GHz. We use the spectral index to split the resulting sample of 599 sources into flat-spectrum and steep-spectrum subsamples. We find that our flat-spectrum sample shows significant ($\\sim3.5\\sigma$) evidence for a correlation between MgII absorption and RM at 1.4 GHz, while our steep-spectrum sample shows no such correlation. We argue that such an effect cannot be explained by either luminosity or other observational effects, by evolution in another confounding variable, by wavelength-dependent polarization structure in an active g...

  2. Lyα-emitting galaxies as a probe of reionization: large-scale bubble morphology and small-scale absorbers

    Science.gov (United States)

    Kakiichi, Koki; Dijkstra, Mark; Ciardi, Benedetta; Graziani, Luca

    2016-12-01

    The visibility of Lyα-emitting galaxies during the Epoch of Reionization is controlled by both diffuse H I patches in large-scale bubble morphology and small-scale absorbers. To investigate their impacts on Lyα transfer, we apply a novel combination of analytic modelling and cosmological hydrodynamical, radiative transfer simulations to three reionization models: (i) the `bubble' model, where only diffuse H I outside ionized bubbles is present; (ii) the `web' model, where H I exists only in overdense self-shielded gas; and (iii) the hybrid `web-bubble' model. The three models can explain the observed Lyα luminosity function equally well, but with very different H I fractions. This confirms a degeneracy between the ionization topology of the intergalactic medium (IGM) and the H I fraction inferred from Lyα surveys. We highlight the importance of the clustering of small-scale absorbers around galaxies. A combined analysis of the Lyα luminosity function and the Lyα fraction can break this degeneracy and provide constraints on the reionization history and its topology. Constraints can be improved by analysing the full MUV-dependent redshift evolution of the Lyα fraction of Lyman break galaxies. We find that the IGM-transmission probability distribution function is unimodal for bubble models and bimodal in web models. Comparing our models to observations, we infer that the neutral fraction at z ˜ 7 is likely to be of the order of tens of per cent when interpreted with bubble or web-bubble models, with a conservative lower limit ˜1 per cent when interpreted with web models.

  3. Lyα-Emitting Galaxies as a Probe of Reionization: Large-Scale Bubble Morphology and Small-Scale Absorbers

    Science.gov (United States)

    Kakiichi, Koki; Dijkstra, Mark; Ciardi, Benedetta; Graziani, Luca

    2016-09-01

    The visibility of Lyα emitting galaxies during the Epoch of Reionization is controlled by both diffuse H I patches in large-scale bubble morphology and small-scale absorbers. To investigate their impacts on Lyα transfer, we apply a novel combination of analytic modelling and cosmological hydrodynamical, radiative transfer simulations to three reionization models: (i) the `bubble' model, where only diffuse H I outside ionized bubbles is present; (ii) the `web' model, where H I exists only in overdense self-shielded gas; and (iii) the hybrid `web-bubble' model. The three models can explain the observed Lyα luminosity function equally well, but with very different H I fractions. This confirms a degeneracy between the ionization topology of the intergalactic medium (IGM) and the H I fraction inferred from Lyα surveys. We highlight the importance of the clustering of small-scale absorbers around galaxies. A combined analysis of the Lyα luminosity function and the Lyα fraction can break this degeneracy and provide constraints on the reionization history and its topology. Constraints can be improved by analyzing the full MUV-dependent redshift evolution of the Lyα fraction of Lyman break galaxies. We find that the IGM-transmission probability distribution function is unimodal for bubble models and bimodal in web models. Comparing our models to observations, we infer that the neutral fraction at z ˜ 7 is likely to be of order of tens of per cent when interpreted with bubble or web-bubble models, with a conservative lower limit ˜1% when interpreted with web models.

  4. Updated Models for the Creation of a Low-z QSO Absorber by a Dwarf Galaxy Wind

    CERN Document Server

    Keeney, Brian A; Stocke, John T; Danforth, Charles W; Levesque, Emily M

    2014-01-01

    We present new GALEX images and optical spectroscopy of J1229+02, a dwarf post-starburst galaxy located 81 kpc from the 1585 km/s absorber in the 3C 273 sight line. The absence of H\\alpha\\ emission and the faint GALEX UV fluxes confirm that the galaxy's recent star formation rate is $1$R_{vir}$ are likely intergalactic systems and cannot be identified unambiguously as the circumgalactic material of any one individual galaxy.

  5. Galaxy interactions II: High density environments

    CERN Document Server

    Alonso, Sol; Padilla, Nelson; Lambas, Diego G

    2011-01-01

    With the aim to assess the role of dense environments in galaxy interactions, properties we present an analysis of close galaxy pairs in groups and clusters, obtained from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). We identified pairs that reside in groups by cross-correlating the total galaxy pair catalogue with the SDSS-DR7 group catalogue from Zapata et al. (2009). We classify pair galaxies according to the intensity of interaction. We analysed the effect of high density environments on different classes of galaxy-galaxy interactions and we have also studied the impact of the group global environment on pair galaxies. We find that galaxy pairs are more concentrated towards the group centres with respect to the other group galaxy members, and disturbed pairs show a preference to contain the brightest galaxy in the groups. The color-magnitude relation exhibits significant differences between pair galaxies and the control sample, consisting in color tails with a clear excess of extremely blue and...

  6. The radio properties of composite liner/H II galaxies

    NARCIS (Netherlands)

    Filho, ME; Barthel, PD; Ho, LC

    2002-01-01

    Arcsecond-resolution VLA observations newly obtained as well as published of 40 nearby galaxies are discussed, completing a study of the radio properties of a magnitude-limited sample of nearby galaxies of the composite LINER/H II type. Our results reveal an overall detection rate of at least 25% ac

  7. Multi-Zone warm and cold clumpy absorbers in 3 Seyfert galaxies

    CERN Document Server

    Ricci, C; Audard, M; Courvoisier, T J -L

    2010-01-01

    We present the first detailed X-ray analysis of three AGN, the Seyfert 1 galaxies UGC 3142 and ESO 140-43, and the Seyfert 2 galaxy ESO 383-18, in order to study the geometry and the physical characteristics of their absorbers. High quality XMM-Newton EPIC and RGS data were analysed, as well as Swift/XRT and BAT and INTEGRAL IBIS/ISGRI data, in order to cover the 0.3--110 keV energy range. For ESO 140-43 also XMM-Newton/OM and Swift/UVOT data were used. We studied the variability of the three AGN on a time-scale of seconds using the EPIC/PN light curves, and the long-term time-scale variability of ESO 140-43 using two observations performed 6 months apart by XMM-Newton. The spectra of the three Seyfert galaxies present a "soft excess'' at energies E < 2 keV above a power-law continuum that can be modeled by complex absorption, without any additional emission component. The X-ray sources in UGC 3142 and ESO 383-18 are absorbed by two layers of neutral material, with covering fractions f_1=0.92 and f_2=0.57 ...

  8. The Contribution of HI-rich Galaxies to the Damped Lyman-alpha Absorber Population at z=0

    CERN Document Server

    Schneider, S E; Schneider, Jessica L. Rosenberg & Stephen E.

    2003-01-01

    We present a study of the expected properties of the low redshift damped Lyman-alpha absorber population determined from a sample of HI-selected galaxies in the local universe. We use measurements of the number density and HI cross-section of galaxies to show that the total HI cross-section at column densities sufficient to produce damped Lyman-alpha absorption is consistent with no evolution of the absorber population. We also find that the dN/dz distribution is dominated by galaxies with HI masses near 10^9 M_solar. However, because of the large dispersion in the correlation between HI mass and stellar luminosity, we find that the distribution of dN/dz as a function of L_J is nearly flat. Additionally, we demonstrate that the linewidths of the HI-selected galaxies are roughly consistent with the kinematics of damped Lyman-alpha absorbers.

  9. From Exoplanets to Quasars: Detection of Potential Damped Lyman Alpha Absorbing Galaxies Using Angular Differential Imaging

    CERN Document Server

    Johnson-Groh, Mara; Ellison, Sara L

    2016-01-01

    The advantages of angular differential imaging (ADI) has been previously untested in imaging the host galaxies of damped Lyman alpha (DLA) systems. In this pilot study, we present the first application of ADI to directly imaging the host galaxy of the DLA seen towards the quasar J1431+3952. K-band imaging of the field surrounding J1431+3952 was obtained on the Gemini North telescope with the adaptive optics system and a laser guide star. We computed a sensitivity curve that demonstrates the sensitivity of our observations as a function of K-band magnitude, impact parameter and DLA angular size. For an impact parameter of 0.5" (3.4 kpc at the redshift of the absorber) our mass sensitivity is log (M_star/M_sun) ~ 9.2 and drops to ~ 9.0 at separations beyond ~ 6 kpc for the smallest size model galaxy. Three candidate galaxies are identified within 5". Stellar masses were computed from the K-band photometry yielding values of log (M_star/M_sun) ~ 9.9, 9.7 and 11.1 respectively. The likely identification of the ab...

  10. Discovery of a Metal-Line Absorber Associated with a Local Dwarf Starburst Galaxy

    CERN Document Server

    Keeney, B A; Rosenberg, J L; Tumlinson, J; York, D G; Keeney, Brian A.; Stocke, John T.; Rosenberg, Jessica L.; Tumlinson, Jason; York, Donald G.

    2006-01-01

    We present optical and near-infrared images, H I 21 cm emission maps, optical spectroscopy, and Hubble Space Telescope/Space Telescope Imaging Spectrograph ultraviolet spectroscopy of the QSO/galaxy pair SBS 1122+594/IC 691. The QSO sight line lies at a position angle of 27 degrees from the minor axis of the nearby dwarf starburst galaxy IC 691 (cz_gal = 1204+-3 km/s, L_B ~ 0.09 L*, current star formation rate = 0.08-0.24 solar masses per year) and 33 kpc (6.6 arcmin) from its nucleus. We find that IC 691 has an H I mass of M_HI = (3.6+-0.1) x 10^8 solar masses and a dynamical mass of M_dyn = (3.1+-0.5) x 10^10 solar masses. The UV spectrum of SBS 1122+594 shows a metal-line (Ly-alpha + C IV) absorber near the redshift of IC 691 at cz_abs = 1110+-30 km/s. Since IC 691 is a dwarf starburst and the SBS 1122+594 sight line lies in the expected location for an outflowing wind, we propose that the best model for producing this metal-line absorber is a starburst wind from IC 691. We place consistent metallicity lim...

  11. Nature of the Absorbing Gas associated with a Galaxy Group at z~0.4

    CERN Document Server

    Peroux, Celine; Quiret, Samuel; Pettini, Max; Kulkarni, Varsha P; York, Donald G; Straka, Lorrie; Husemann, Bernd; Milliard, Bruno

    2016-01-01

    We present new MUSE observations of quasar field Q2131-1207 with a log N(HI)=19.50+/-0.15 sub-DLA at z_abs=0.42980. We detect four galaxies at a redshift consistent with that of the absorber where only one was known before this study. Two of these are star forming galaxies, while the ones further away from the quasar (>140 kpc) are passive galaxies. We report the metallicities of the HII regions of the closest objects (12+log(O/H)=8.98+/-0.02 and 8.32+/-0.16) to be higher or equivalent within the errors to the metallicity measured in absorption in the neutral phase of the gas (8.15+/-0.20). For the closest object, a detailed morpho-kinematic analysis indicates that it is an inclined large rotating disk with V_max=200+/-3 km/s. We measure the masses to be M_dyn=7.4+/-0.4 x 10^10 M_sun and M_halo=2.9+/-0.2 x 10^12 M_sun. Some of the gas seen in absorption is likely to be co-rotating with the halo of that object, possibly due to a warped disk. The azimuthal angle between the quasar line of sight and the projecte...

  12. The (C II) 158 micron line mapping of spiral galaxies

    Science.gov (United States)

    Stacey, Gordon J.; Geis, N.; Genzel, Reinhard; Jackson, J. M.; Poglitsch, Albrecht; Townes, Charles H.

    1990-01-01

    Large scale maps of the face of spiral galaxies M51, M83, and NGC 6946 in the 158 micron (C II) fine structure line. The maps are obtained from the Far-infrared Imaging Fabry-Perot Interferometer (FIFI) during its first series of flights on board the Kuiper Airborne Observatory. The (C II) line emission is ubiquitous and easily traced over the mapped regions of each of the galaxies. The (C II) maps are compared with those obtained with similar sized beams in the CO line. The data available from these maps is interpreted.

  13. The warm absorber of the Seyfert 1 galaxy H1419+480

    CERN Document Server

    Barcons, X; Ceballos, M T

    2003-01-01

    The bright Seyfert 1 galaxy H1419+480 (z~0.072), whose X-ray colours from earlier HEAO-1 and ROSAT missions suggested a complex X-ray spectrum, has been observed with XMM-Newton. The EPIC spectrum is well fit by a power-law with photon index ~1.84 and an Fe Ka line of equivalent width ~250 eV. At low energies, an intrinsic OVII K-edge is unambiguously detected with a depth ~ 0.45, but no OVIII absorption edge is detected to within sensitive limits. The absorption features are equally well fit by an ionised absorber (ionisation parameter ~ a few) with column density NH ~ 2.5E21 cm^-2 for solar abundances. We find that the flux of this source has varied with respect to earlier ROSAT observations, and there are hints that the warm absorber was weaker or absent in that previous observation. An IUE spectrum of this source shows an associated and variable (within a year) CIV absorber outflowing with a velocity \\~1800 km/s. We argue that both the UV and X-ray absorption can be consistently modelled in terms of photo...

  14. Precious metals in SDSS quasar spectra. II. Tracking the evolution of strong, 0.4 < z < 2.3 Mg II absorbers with thousands of systems

    Energy Technology Data Exchange (ETDEWEB)

    Seyffert, Eduardo N.; Simcoe, Robert A. [Department of Physics, MIT, 77 Massachusetts Avenue, 37-664D, Cambridge, MA 02139 (United States); Cooksey, Kathy L. [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-685, Cambridge, MA 02139 (United States); O' Meara, John M. [Department of Chemistry and Physics, Saint Michael' s College, One Winooski Park, Colchester, VT 05439 (United States); Kao, Melodie M. [Caltech, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Prochaska, J. Xavier, E-mail: enseyff@mit.edu, E-mail: simcoe@space.mit.edu, E-mail: kcooksey@space.mit.edu, E-mail: jomeara@smcvt.edu, E-mail: mkao@caltech.edu, E-mail: xavier@ucolick.org [Department of Astronomy and UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2013-12-20

    We have performed an analysis of over 34,000 Mg II doublets at 0.36 < z < 2.29 in Sloan Digital Sky Survey (SDSS) Data Release 7 quasar spectra; the catalog, advanced data products, and tools for analysis are publicly available. The catalog was divided into 14 small redshift bins with roughly 2500 doublets in each and from Monte Carlo simulations, we estimate 50% completeness at rest equivalent width W {sub r} ≈ 0.8 Å. The equivalent width frequency distribution is described well by an exponential model at all redshifts, and the distribution becomes flatter with increasing redshift, i.e., there are more strong systems relative to weak ones. Direct comparison with previous SDSS Mg II surveys reveals that we recover at least 70% of the doublets in these other catalogs, in addition to detecting thousands of new systems. We discuss how these surveys came by their different results, which qualitatively agree but because of the very small uncertainties, differ by a statistically significant amount. The estimated physical cross section of Mg II-absorbing galaxy halos increased approximately threefold from z = 0.4 to z = 2.3, while the W {sub r} ≥ 1 Å absorber line density, dN{sub MgII}/dX, grew by roughly 45%. Finally, we explore the different evolution of various absorber populations—damped Lyα absorbers, Lyman limit systems, strong C IV absorbers, and strong and weaker Mg II systems—across cosmic time (0 < z < 6).

  15. Lopsidedness in WHISP galaxies: II. Morphological lopsidedness

    CERN Document Server

    van Eymeren, J; Jog, C J; Stein, Y; Dettmar, R -J

    2011-01-01

    The distribution of stars and gas in many galaxies is asymmetric. This so-called lopsidedness is expected to significantly affect the dynamics and evolution of the disc, including the star formation activity. Here, we measure the degree of lopsidedness for the gas distribution in a selected sample of 70 galaxies from the Westerbork HI Survey of Spiral and Irregular Galaxies. This complements our earlier work (Paper I) where the kinematic lopsidedness was derived for the same galaxies. The morphological lopsidedness is measured by performing a harmonic decomposition of the surface density maps. The amplitude of lopsidedness A_1, the fractional value of the first Fourier component, is typically quite high (about 0.1) within the optical disc and has a constant phase. Thus, lopsidedness is a common feature in galaxies and indicates a global mode. We measure A_1 out to typically one to four optical radii, sometimes even further. This is, on average, four times larger than the distance to which lopsidedness was mea...

  16. The Warm Absorber constrained by the coronal lines in Seyfert 1 galaxies

    CERN Document Server

    Porquet, D; Collin, S; Mouchet, M; Porquet, Delphine; Dumont, Anne-Marie; Collin, Suzy; Mouchet, Martine

    1999-01-01

    We present results of the photoionization code IRIS, which calculates the spectrum emitted by the Warm Absorber (WA) in Seyfert 1 galaxies for a large grid of parameters (density, column density, ionization parameter...). We show that in Seyfert 1s, coronal lines ([Fe X], [Fe XI], [Fe XIV]...), unlike the absorption edges, such as those of O VII and O VIII observed in soft X-rays which are produced by the WA, strongly constrain the physical parameters of the WA, especially the hydrogen density. Indeed, in order to avoid producing coronal line equivalent widths larger than observed, a high density ($n_{H} models (photoionized medium in or out of thermal equilibrium). This result is obtained for the mean observed Seyfert 1 features, as well as for the case study of MCG-6-30-15. It implies that the distance of the WA from the incident radiation source is of the order of that of the Broad Line Region (BLR).

  17. The AMIGA sample of isolated galaxies - II. Morphological refinement

    CERN Document Server

    Sulentic, J W; Bergond, G; Lisenfeld, U; Durbala, A; Espada, D; García, E; Leon, S; Sabater, J; Verley, S; Casanova, V; Sota, A

    2005-01-01

    We present a complete POSS II-based refinement of the optical morphologies for galaxies in the Karatchenseva's Catalog of Isolated Galaxies that forms the basis of the AMIGA project. Comparison with independent classifications made for an SDSS overlap sample of more than 200 galaxies confirms the reliability of the early vs. late-type discrimination and the accuracy of spiral subtypes within DeltaT = 1-2. CCD images taken at the OSN were also used to solve ambiguities. 193 galaxies are flagged for the presence of nearby companions or signs of distortion likely due to interaction. This most isolated sample of galaxies in the local Universe is dominated by 2 populations: 1) 82% spirals (Sa-Sd) with the bulk being luminous systems with small bulges (63% between types Sb-Sc) and 2) a significant population of early-type E-S0 galaxies (14%). Most of the types later than Sd are low luminosity galaxies concentrated in the local supercluster where isolation is difficult to evaluate. The late-type spiral majority of t...

  18. X-Ray Emitting-Absorbing Media in Seyfert 1 Galaxies

    CERN Document Server

    Mouchet, M; Porquet, D; Dumont, A M; Collin, S

    2000-01-01

    Seyfert galaxies have been shown to exhibit a large variety of features in their X-ray spectra from which the environment of the central engine can be deduced. We focus on the two following aspects: the Warm Absorber, mainly responsible of the soft X-ray properties, and the reprocessing/reflecting plasma medium at the origin of the iron Kalpha fluorescent line. The physical parameters and the location of the so-called Warm Absorber (WA), a photoionized medium along the line of sight to the nuclear region, are more strongly constrained by optical coronal lines than by the oxygen edges observed in the soft X-rays and produced by the WA. The photoionization models also predict the intensities of the X-ray emission lines which are going to be detected with the new generation of X-ray satellites. An alternative model to the relativistic accretion disc is proposed to explain the profile of the X-ray iron Kalpha line observed in the Seyfert 1. This line can be formed in the framework of a quasi-spherical accretion o...

  19. Starburst in the interacting HII galaxy II Zw 40 and in non-interacting HII galaxies

    CERN Document Server

    Telles, Eduardo

    2009-01-01

    I summarize the results of our integral field spectroscopic observations of the nearby prototype of HII galaxies, II Zw 40. Observations with GMOS-IFU on GEMINI-North in the optical allowed us to make a detailed kinematic picture of the central starburst, while SINFONI with adaptive optics on the ESO-VLT gave us a near-IR view of the interplay between the ISM phases. Here, I also address the question that not all starbursts require an external trigger such as a galaxy-galaxy encounter, as it seems to be the case for a fraction of low luminosity HII galaxies. We speculate that these may form stars spontaneously like "pop-corn in a pan".

  20. Properties of QSO Metal Line Absorption Systems at High Redshifts: Nature and Evolution of the Absorbers and New Evidence on Escape of Ionizing Radiation from Galaxies

    CERN Document Server

    Boksenberg, Alec

    2014-01-01

    Using Voigt-profile-fitting procedures on Keck HIRES spectra of nine QSOs we identify 1099 CIV absorber components clumped in 201 systems outside the Lyman forest over 1.6 < z < 4.4. With associated SiIV, CII, SiII and NV where available we investigate bulk statistical and ionization properties of the components and systems and find no significant change in redshift for CIV and SiIV while CII, SiII and NV change substantially. The CIV components exhibit strong clustering but no clustering is detected for systems on scales from 150 km/s out to 50000 km/s. We conclude the clustering is due entirely to the peculiar velocities of gas present in the circumgalactic media of galaxies. Using specific combinations of ionic ratios we compare our observations with model ionization predictions for absorbers exposed to the metagalactic ionizing radiation background augmented by proximity radiation from their associated galaxies and find the generally accepted means of radiative escape by transparent channels from th...

  1. Lyman-Alpha Emitting Galaxies as a Probe of Reionization: Large-Scale Bubble Morphology and Small-Scale Absorbers

    CERN Document Server

    Kakiichi, Koki; Ciardi, Benedetta; Graziani, Luca

    2015-01-01

    The visibility of LyA emitting galaxies during the Epoch of Reionization is controlled by both diffuse HI patches in large-scale bubble morphology and small-scale absorbers. To investigate the impact on LyA photons, we apply a novel combination of analytic and numerical calculations to three scenarios: (i) the `bubble' model, where only diffuse HI outside ionized bubbles is present; (ii) the `web' model, where HI exists only in overdense self-shielded gas; and (iii) the more realistic 'web-bubble' model, which contains both. Our analysis confirms that there is a degeneracy between the ionization structure of the intergalactic medium (IGM) and the HI fraction inferred from LyA surveys, as the three models suppress LyA flux equally with very different HI fractions. We argue that a joint analysis of the LyA luminosity function and the rest-frame equivalent width distribution/LyA fraction can break this degeneracy and provide constraints on the reionization history and its topology. We further show that constrain...

  2. The Dragonfly Nearby Galaxies Survey. II. Ultra-Diffuse Galaxies near the Elliptical Galaxy NGC 5485

    Science.gov (United States)

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

    2016-12-01

    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 the 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\\gt 17.5 Mpc. We show that the galaxies are most likely associated with a background group at ˜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 demonstrates that the UDG phenomenon is not exclusive to cluster environments. Furthermore, their morphologies seem less regular than those of the cluster populations, which may suggest a different formation mechanism or be indicative of a threshold in surface density below which UDGs are unable to maintain stability.

  3. 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...

  4. CaII Absorbers in the Sloan Digital Sky Survey: Element Abundances and Dust

    CERN Document Server

    Sardane, Gendith M; Rao, Sandhya M

    2015-01-01

    We present measurements of element abundance ratios and dust in CaII~absorbers identified in SDSS DR7+DR9. In an earlier paper we formed a statistical sample of 435 CaII absorbers and postulated that their statistical properties might be representative of at least two populations of absorbers. Here we show that if the absorbers are roughly divided into two subsamples with CaII rest equivalent widths larger and smaller than $W_0^{\\lambda 3934} = 0.7$ \\AA, they are then representative of two physically different populations. Comparisons of abundance ratios between the two CaII absorber populations indicate that the weaker $W_0^{\\lambda 3934}$ absorbers have properties consistent with halo-type gas, while the stronger absorbers have properties intermediate between halo- and disk-type gas. We also show that, on average, the dust extinction properties of the overall sample is consistent with a LMC or SMC dust law, and the stronger absorbers are nearly 6 times more reddened than their weaker counterparts. The absor...

  5. Cold gas kinematics in an L(*) spiral Galaxy at z=0.437 : The nature of damped Lyman-alpha absorbers

    NARCIS (Netherlands)

    Briggs, FH; de Bruyn, AG; Vermeulen, RC

    2001-01-01

    Westerbork Radio Synthesis Telescope observations of the redshifted 21 cm line absorber against the z(em) = 0.871 double lobed quasar 3C 196 show that the intervening absorber is an L approximate toL(*) spiral galaxy (3C 196-G1) and that the absorbing layer of cold gas extends to radii of at least 3

  6. Mg II Absorption Characteristics of a Volume-Limited Sample of Galaxies at z ~ 0.1

    Science.gov (United States)

    Barton, Elizabeth J.; Cooke, Jeff

    2009-12-01

    We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey (SDSS). We observed quasars near sightlines to 20 low-redshift (z ~ 0.1), luminous (M r + 5log h background quasar within a projected 75 h -1 kpc of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong (W eq(2796) >= 0.3 Å) Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong (W eq(2796) >= 1-2 Å) absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction fc lsim 0.4 for >=0.3 Å absorbers at z ~ 0.1, even at impact parameters Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  7. From Exoplanets to Quasars: Detection of Potential Damped Lyα Absorbing Galaxies Using Angular Differential Imaging

    Science.gov (United States)

    Johnson-Groh, Mara; Marois, Christian; Ellison, Sara L.

    2016-11-01

    The advantages of angular differential imaging (ADI) have been previously untested in imaging the host galaxies of damped Lyα (DLA) systems. In this pilot study, we present the first application of ADI to directly image the host galaxy of the DLA seen toward the quasar J1431+3952. K-band imaging of the field surrounding J1431+3952 was obtained on the Gemini North telescope with an adaptive optics system and a laser guide star. We computed a sensitivity curve that demonstrates the sensitivity of our observations as a function of K-band magnitude, impact parameter and DLA angular size. For an impact parameter of 0.″5 (3.4 kpc at the redshift of the absorber) our mass sensitivity is log (M {}\\star /M {}⊙ ) ˜ 9.2 and drops to ˜9.0 at separations beyond ˜6 kpc for the smallest size model galaxy. Three candidate galaxies are identified within 5″. Stellar masses were computed from the K-band photometry yielding values of log (M {}\\star /M {}⊙ ) ˜ 9.9, 9.7 and 11.1 respectively. The likely identification of the absorbing galaxy is discussed, and we conclude that the galaxy with the largest impact parameter and highest stellar mass is unlikely to be the host, based on its inconsistency with the N(HI) impact parameter relation and inconsistent photometric redshift. While we cannot distinguish between the remaining two candidates as the DLA host, we note that, despite the low spin temperature and relatively high metallicity of the DLA, the host does not appear to be a particularly luminous (high-mass) galaxy.

  8. A Method to Measure the Mass of Damped Ly-alpha Absorber Host Galaxies Using Fluctuations in 21cm Emission

    CERN Document Server

    Wyithe, Stuart

    2008-01-01

    Observations of damped Ly-alpha absorbers (DLA) indicate that the fraction of hydrogen in its neutral form (HI) is significant by mass at all redshifts. This gas represents the reservoir of material that is available for star formation at late times. As a result, observational identification of the systems in which this neutral hydrogen resides is an important missing ingredient in models of galaxy formation. Precise identification of DLA host mass via traditional clustering studies is not practical owing to the small numbers of known systems being spread across sparsely distributed sight lines. However following the completion of reionization, 21cm surface brightness fluctuations will be dominated by neutral hydrogen in DLAs. Observations of these fluctuations will measure the combined clustering signal from all DLAs within a large volume. We show that measurement of the spherically averaged power-spectrum of 21cm intensity fluctuations due to DLAs could be used to measure the galaxy bias for DLA host galaxi...

  9. The Enigma of the Strong MgII Absorbers along the GRB Sightlines

    Science.gov (United States)

    Cucchiara, Antonino; Charlton, J.; Jones, T.; Fox, D. B.; Narayan, A.; Narayan, A.

    2009-01-01

    The startling result of Prochter & Prochaska (2006) that the incidence of strong MgII absorbers (equivalent width EW(2796Å) > 1 Å) along gamma-ray burst (GRB) sightlines is four times larger (dN/dzGR=0.90) than for quasar sightlines (dN/dzQSO=0.24) has yet to be understood. In particular, explanations relating to dust bias in quasar samples, partial covering of quasars, and lensing amplification of the GRB beam all fail to satisfy basic observational constraints. We are currently engaged in an effort to explore this mystery using archival VLT/UVES (R=45,000) quasar and afterglow spectra. Identifying strong MgII absorbers in a uniform and statistically complete manner, we have compiled a sample of 28 absorbers toward 81 quasars and 9 absorbers toward 6 GRB afterglows. We explore the kinematics of the absorbers, the abundances of other metal species, and the strength of dust depletion in the GRB and QSO samples. We fail to identify any respects in which 75% of the GRB line-of-sight absorbers can be distinguished from the other members of the GRB and QSO absorber populations. We consider whether this finding rules out the possibility of an intrinsic high-velocity (v 0.2 c) GRB or GRB host-related origin for the excess absorbers, and conclude that it does not.

  10. Precious Metals in SDSS Quasar Spectra II: Tracking the Evolution of Strong, 0.4 < z < 2.3 MgII Absorbers with Thousands of Systems

    CERN Document Server

    Seyffert, Eduardo N; Simcoe, Robert A; O'Meara, John M; Kao, Melodie M; Prochaska, J Xavier

    2013-01-01

    We have performed an analysis of over 34,000 MgII doublets at 0.36 2.3, while the W_r >= 1 \\AA absorber line density grew, dN_MgII/dX, by roughly 45%. Finally, we explore the different evolution of various absorber populations---damped Lyman-alpha absorbers, Lyman-limit systems, strong CIV absorbers, and strong and weaker MgII systems---across cosmic time (0 < z < 6).

  11. On the Incidence and Kinematics of Strong Mg II Absorbers

    CERN Document Server

    Prochter, G E; Burles, S; Prochter, Gabriel E.; Prochaska, Jason X.; Burles, Scott

    2004-01-01

    We present the results of two complementary investigations into the nature and incidence of strong (rest equivalent width, W_r > 1.0 Angstrom) Mg II absorption systems at high redshift. The first line of questioning employs the Sloan Digital Sky Survey Data Release 2 set of r' < 20.5 quasar spectra to collect a large set of systems for the purpose of determining the redshift path density (dN/dz) of strong Mg II absorption. A power-law fit to this distribution results in dN/dz = 0.094(1+z)^(1.29) for 0.35 < z < 2.3. We also present the results of a search for strong Mg II absorption in a set of 91 high resolution quasar spectra collected on the ESI and HIRES spectrographs. These data allow us to investigate the kinematics of such systems at 0.8 < z < 2.7. We find that these systems tend to have complicated kinematic profiles. Also, absorption due to more highly ionized species (e.g., Al III, C IV, Si IV) tend to display kinematic profiles similar to those of the associated Mg II absorption. We c...

  12. Starburst-AGN mixing: II. Optically-selected active galaxies

    CERN Document Server

    Davies, Rebecca L; Ho, I-Ting; Dopita, Michael A

    2014-01-01

    We use 4 galaxies from the Calar Alto Legacy Integral Field Area (CALIFA) survey with clear signs of accretion onto supermassive black holes to investigate the relative contribution of star-formation and active galactic nucleus (AGN) activity to the line-emission of each galaxy as a function of radius. The combination of star-formation and AGN activity produces curved "mixing sequences" on standard optical diagnostic diagrams, and the fraction of emission due to AGN activity decreases smoothly with distance from the centre of the galaxy. We use the AGN activity profiles to calculate the size of the AGN narrow line regions, which have radii of ~ 6.3 kpc. We calculate the fractional contribution of the star-formation and the AGN activity to the global Halpha, [O II] $\\lambda \\lambda$ 3727,3729 and [O III] $\\lambda$ 5007 luminosities of each galaxy, and show that both ionization sources contribute significantly to the emission in all three lines. We use weighted combinations of stellar and AGN photoionization mo...

  13. The structure of Andromeda II dwarf spheroidal galaxy

    CERN Document Server

    del Pino, Andrés; Hidalgo, Sebastian L; Fouquet, Sylvain

    2016-01-01

    We analyze in detail the spatial distribution and kinematic properties of two different stellar populations in Andromeda II (And II) dwarf spheroidal galaxy. We obtained their detailed surface density maps, together with their radial density profiles. The two populations differ not only in age and metallicity, but also in their spatial distribution and kinematics. Old stars ($\\gtrsim 11$ Gyr) follow a round distribution well fitted by truncated density profiles. These stars rotate around the projected optical major axis of the galaxy with line-of-sight velocities $v_{los}(r_h) = 16 \\pm 3$ km s$^{-1}$ and a velocity gradient of $2.06 \\pm 0.21$ km s$^{-1}$ arcmin$^{-1}$. Intermediate-age stars ($\\lesssim 9$ Gyr) concentrate in the centre of the galaxy and form an elongated structure extending along the projected optical major axis. This structure appears to rotate with a steeper velocity gradient, $2.24 \\pm 0.22$ km s$^{-1}$ arcmin$^{-1}$, and around the optical minor axis. The centres of rotation and kinetic p...

  14. Small Scale Structure at High Redshift II. Physical Properties of the CIV Absorbing Clouds

    CERN Document Server

    Rauch, M; Barlow, T A; Rauch, Michael; Sargent, Wallace L.W.; Barlow, Thomas A.

    2001-01-01

    Keck HIRES spectra were obtained of the separate images of three gravitationally lensed QSOs (UM 673, Q1104-1804, and Q1422+2309). We studied the velocity and column density differences in CIV doublets in each QSO. Unlike the low ionization gas clouds typical of the interstellar gas in the Galaxy or damped Ly alpha galaxies, the spatial density distribution of CIV absorbing gas clouds turns out to be mostly featureless on scales up to a few hundred parsecs, with column density differences rising to 50 percent or more over separations beyond a few kpc. Similarly, velocity shear becomes detectable only over distances larger than a few hundred pc, rising to 70 km/s at a few kpc. The energy transmitted to the gas is substantially less than in present day star-forming regions, and the gas is less turbulent on a given spatial scale than, e.g., local HII regions. The quiescence of CIV clouds, taken with their probable low density, imply that these objects are not internal to galaxies. The CIV absorbers could be gas ...

  15. Triangulum II: A Very Dense Ultra-Faint Dwarf Galaxy

    CERN Document Server

    Kirby, Evan N; Simon, Joshua D; Guhathakurta, Puragra

    2015-01-01

    Laevens et al. recently discovered Triangulum II, a satellite of the Milky Way. Its Galactocentric distance is 36 kpc, and its luminosity is only 450 L_sun. We measured the radial velocities of six members stars with Keck/DEIMOS, and we found a velocity dispersion of sigma_v = 5.1 -1.4 +4.0 km/s. We also measured the metallicities of three stars and found a range of 0.8 dex in [Fe/H]. The velocity and metallicity dispersions identify Triangulum II as a dark matter-dominated galaxy. The galaxy is moving very quickly toward the Galactic center (v_GSR = -262 km/s). Although it might be in the process of being tidally disrupted as it approaches pericenter, there is no strong evidence for disruption. The ellipticity is low, and the mean velocity, = -382.1 +/- 2.9 km/s, rules out an association with the Triangulum-Andromeda substructure or the Pan-Andromeda Archaeological Survey (PAndAS) stellar stream. If Triangulum II is in dynamical equilibrium, then it would have a mass-to-light ratio of 3600 -2100 +3500 M_sun...

  16. A Deep Search for Faint Galaxies Associated with Very Low-Redshift C IV Absorbers: A Case with Cold-Accretion Characteristics

    CERN Document Server

    Burchett, Joseph N; Werk, Jessica K; Howk, J Christopher; Prochaska, J Xavier; Ford, Amanda Brady; Davé, Romeel

    2013-01-01

    Studies of QSO absorber-galaxy connections are often hindered by inadequate information on whether faint/dwarf galaxies are located near the QSO sight lines. To investigate the contribution of faint galaxies to QSO absorber populations, we are conducting a deep galaxy redshift survey near low-z C IV absorbers. Here we report a blindly-detected C IV absorption system (z(abs) = 0.00348) in the spectrum of PG1148+549 that appears to be associated either with an edge-on dwarf galaxy with an obvious disk (UGC 6894, z(gal) = 0.00283) at an impact parameter of rho = 190 kpc or with a very faint dwarf irregular galaxy at rho = 23 kpc, which is closer to the sightline but has a larger redshift difference (z(gal) = 0.00107, i.e., dv = 724 km/s). We consider various gas/galaxy associations, including infall and outflows. Based on current theoretical models, we conclude that the absorber is most likely tracing (1) the remnants of an outflow from a previous epoch, a so-called 'ancient outflow', or (2) intergalactic gas ac...

  17. The Kinematics of Intermediate Redshift Mg II Absorbers

    CERN Document Server

    Churchill, C W; Churchill, Chris; Vogt, Steven S.

    2001-01-01

    [Abridged] We present 23 quasar absorption line systems selected by the MgII doublet with W_r(2796)>0.3 Ang over the redshift range 0.40.2 Ang and velocity spreads ranging from 10-50 km/s, in proportion to the system equivalent width. Additional kinematic subsystems have velocities out to ~400 km/s. The equivalent widths and velocity spreads of these "outlying", weaker subsystems are anti-correlated with their velocities and their equivalent width distribution turns down from a power law below W_r~0.08 Ang. These "moderate" and "high velocity" subsystems and probably not higher redshift analogues to Galactic high velocity clouds (HVCs). Weak subsystems are asymmetrically distributed in velocity; they are either all blueshifted or all redshifted with respect to the dominant subsystem. This implies, that on a case-by-case basis, a given line of sight is apparently probing a well defined spatial and kinematic structure. We investigate a simple kinematic model that relies on a rotating disk to explain the observe...

  18. Effects of interaction on the properties of spiral galaxies. II. Isolated galaxies: The zero point

    Science.gov (United States)

    Márquez, I.; Moles, M.

    1999-04-01

    We analyse the properties of a sample of 22 bright isolated spiral galaxies on the basis of Johnson B,V,I images and optical rotation curves. The fraction of early morphological types in our sample of isolated galaxies (or in other samples of non-interacting spiral galaxies) appears to be smaller than in samples including interacting systems. The overall morphological aspect is regular and symmetric, but all the galaxies present non-axisymmetric components in the form of bars or rings. We find that the color indices become bluer towards the outer parts and that their central values are well correlated with the total colors. The properties of the bulges span a larger range than those of the disks, that thus are more alike between them. None of the galaxies shows a truncated, type II disk profile. It is found that the relation between surface brightness and size for the bulges, the Kormendy relation, is tighter when only isolated galaxies are considered. We find a similar relation for the disk parameters with an unprecedented low scatter. A Principal Component Analysis of the measured parameters shows that 2 eigenvectors suffice to explain more than 95 % of the total variance. These are, as found for other samples including spiral galaxies in different environmental situations, a scale parameter given by the mass or, equivalently, the luminosity or the size; and a form parameter given by the bulge to disk luminosity ratio, B/D, or, equivalently, by the gradient of the solid-body rotation region of the rotation curve, the G-parameter. We report here a tight correlation between G and B/D for our sample of isolated spirals that could be used as a new distance indicator. Based on data obtained at the 1.5m telescope of the Estacion de Observacion de Calar Alto, Instituto Geografico Nacional, which is jointly operated by the Instituto Geografico Nacional and the Consejo Superior de Investigaciones Cientificas through the Instituto de Astrofisica de Andalucia

  19. [C II] and [N II] from dense ionized regions in the Galaxy

    CERN Document Server

    Langer, W D; Pineda, J L

    2016-01-01

    The interstellar medium (ISM) consists of highly ionized and neutral atomic, as well as molecular, components. Knowledge of their distribution is important for tracing the structure and lifecycle of the ISM. Here we determine the properties of the highly ionized and neutral weakly ionized gas in the Galaxy traced by the fine-structure lines of ionized nitrogen, [N II], and ionized carbon, [C II]. To analyze the ionized ISM we utilize [C II] 158 micron and [N II] 205 micron lines taken with the high spectral resolution Heterodyne Instrument in the Far-Infrared (HIFI) on the Herschel Space Observatory along ten lines of sight towards the inner Galaxy. [N II] emission can be used to estimate the contribution of the highly ionized gas to the [C II] emission and separate the highly ionized and weakly ionized neutral gas. We find that [N II] has strong emission in distinct spectral features along all lines of sight associated with strong [C II] emission. The [N II] arises from moderate density extended HII regions ...

  20. Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Nemmen, R. S.; Braito, V.; Gaspari, M.; Reynolds, C. S.

    2013-04-01

    The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent with previous studies. The fraction of sources with UFOs is >34 per cent, >67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show

  1. Unification of X-ray Winds in Seyfert Galaxies: From Ultra-fast Outflows to Warm Absorbers

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Nemmen, R. S.; Braito, V.; Gaspari, M.; Reynolds, C. S.

    2013-01-01

    The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent with previous studies. The fraction of sources with UFOs is >34 per cent, >67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show

  2. PROBING CLUSTER GALAXIES WITH BACKGROUND QSOS

    Directory of Open Access Journals (Sweden)

    S. Lopez

    2009-01-01

    Full Text Available We present the results of the rst survey of intervening Mg II absorption systems associated with high-z cluster galaxies. We investigated the incidence (dN=dz of Mg II absorbers in hzi = 0:6 cluster galaxies from the Red-Sequence Cluster Survey. While strong (W0 > 1:0 A absorbers show a signi cant excess (up to 10, weak (W0 < 0:3 A absorbers conform to the eld statistics. We argue that this dichotomy could be explained if cluster galaxies that give rise to weak Mg II absorption have their cold halos truncated as a consequence of environmental e ects.

  3. Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers

    CERN Document Server

    Tombesi, F; Reeves, J N; Nemmen, R S; Braito, V; Gaspari, M; Reynolds, C S

    2012-01-01

    The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60%, consistent with previous studies. The fraction of sources with UFOs is >34%, >67% of which also show WAs. The large dynamic range obtained when considering all the absorbers together allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ioniza...

  4. Spectroscopy of Outlying H II Regions in Spiral Galaxies Abundances and Radial Gradients

    CERN Document Server

    Van Zee, L; Haynes, M P; O'Donoghue, A A; Balonek, T J

    1998-01-01

    We present the results of low dispersion optical spectroscopy of 186 H II regions spanning a range of radius in 13 spiral galaxies. Abundances for several elements (oxygen, nitrogen, neon, sulfur, and argon) were determined for 185 of the H II regions. As expected, low metallicities were found for the outlying H II regions of these spiral galaxies. Radial abundance gradients were derived for the 11 primary galaxies; similar to results for other spiral galaxies, the derived abundance gradients are typically -0.04 to -0.07 dex/kpc.

  5. Integral field spectroscopy of a sample of nearby galaxies: II. Properties of the H ii regions

    CERN Document Server

    Sanchez, S F; Marino, R A; Iglesias-Paramo, J; Vilchez, J M; Kennicutt, R C; Diaz, A I; Mast, D; Monreal-Ibero, A; Garcia-Benito, R; Bland-Hawthorn, J; Perez, E; Delgado, R Gonzalez; Husemann, B; Lopez-Sanchez, A R; Fernandes, R Cid; Kehrig, C; Walcher, C J; de Paz, A Gil; Ellis, S

    2012-01-01

    In this work we analyze the spectroscopic properties of a large number of H ii regions, \\sim2600, located in 38 galaxies. The sample of galaxies has been assembled from the face-on spirals in the PINGS survey and a sample described in M\\'armol-Queralt\\'o (2011, henceforth Paper I). All the galaxies were observed using Integral Field Spectroscopy with a similar setup, covering their optical extension up to \\sim2.4 effective radii within a wavelength range from \\sim3700 to \\sim6900{\\AA}. We develop a new automatic procedure to detect H ii regions, based on the contrast of the H{\\alpha} intensity maps. Once detected, the procedure provides us with the integrated spectra of each individual segmented region. A well-tested automatic decoupling procedure has been applied to remove the underlying stellar population, deriving the main proper- ties of the strongest emission lines in the considered wavelength range (covering from [O ii] {\\lambda}3727 to [S ii] {\\lambda}6731). A final catalogue of the spectroscopic prope...

  6. Enhanced infrared detectors using resonant structures combined with thin type-II superlattice absorbers

    Science.gov (United States)

    Goldflam, M. D.; Kadlec, E. A.; Olson, B. V.; Klem, J. F.; Hawkins, S. D.; Parameswaran, S.; Coon, W. T.; Keeler, G. A.; Fortune, T. R.; Tauke-Pedretti, A.; Wendt, J. R.; Shaner, E. A.; Davids, P. S.; Kim, J. K.; Peters, D. W.

    2016-12-01

    We examined the spectral responsivity of a 1.77 μm thick type-II superlattice based long-wave infrared detector in combination with metallic nanoantennas. Coupling between the Fabry-Pérot cavity formed by the semiconductor layer and the resonant nanoantennas on its surface enables spectral selectivity, while also increasing peak quantum efficiency to over 50%. Electromagnetic simulations reveal that this high responsivity is a direct result of field-enhancement in the absorber layer, enabling significant absorption in spite of the absorber's subwavelength thickness. Notably, thinning of the absorbing material could ultimately yield lower photodetector noise through a reduction in dark current while improving photocarrier collection efficiency. The temperature- and incident-angle-independent spectral response observed in these devices allows for operation over a wide range of temperatures and optical systems. This detector paradigm demonstrates potential benefits to device performance with applications throughout the infrared.

  7. Low and High Ionization Absorption Properties of Mg II Absorption-Selected Galaxies at Intermediate Redshifts; 1, General Properties

    CERN Document Server

    Churchill, C W; Charlton, J C; Jannuzi, B T; Kirhakos, S; Steidel, C C; Schneider, D P; Churchill, Christopher W.; Mellon, Richard R.; Charlton, Jane C.; Jannuzi, Buell T.; Kirhakos, Sofia; Steidel, Charles C.; Schneider, Donald P.

    2000-01-01

    We present extensive metal-line absorption properties for 45 absorption systems that were selected by their Mg II absorption at redshifts between 0.4 and 1.4. For each system the properties of several chemical species are determined, including a wide range of ionization conditions. In the optical, the absorption systems have been observed at ~6 km/s resolution with HIRES/Keck, which covered Mg II, several Fe II transitions, Mg I, and in some cases (depending upon redshift), Ca II, Ti II, Mn II, and Al III. Ultraviolet, lower resolution (~230 km/s) Faint Object Spectrograph data (1600 - 3275 Ang) were obtained from the Hubble Space Telescope archive. These spectra covered Al II, Al III, Si II, Si III, Si IV, C II, C III, C IV, N V, O VI, and several Lyman series transitions, with coverage dependent upon the absorption system redshift. From these data, we infer that Mg II absorbing galaxies at intermediate redshifts have multiphase gaseous structures.

  8. A DEEP SEARCH FOR FAINT GALAXIES ASSOCIATED WITH VERY LOW-REDSHIFT C IV ABSORBERS: A CASE WITH COLD-ACCRETION CHARACTERISTICS

    Energy Technology Data Exchange (ETDEWEB)

    Burchett, Joseph N.; Tripp, Todd M. [Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003-9305 (United States); Werk, Jessica K.; Prochaska, J. Xavier [UCO/Lick Observatory, University of California, Santa Cruz, CA 95140 (United States); Howk, J. Christopher [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Ford, Amanda Brady [Astronomy Department, University of Arizona, Tucson, AZ 85721 (United States); Davé, Romeel, E-mail: jburchet@astro.umass.edu [University of the Western Cape, Bellville, Cape Town 7535 (South Africa)

    2013-12-20

    Studies of QSO absorber-galaxy connections are often hindered by inadequate information on whether faint/dwarf galaxies are located near the QSO sight lines. To investigate the contribution of faint galaxies to QSO absorber populations, we are conducting a deep galaxy redshift survey near low-z C IV absorbers. Here we report a blindly detected C IV absorption system (z {sub abs} = 0.00348) in the spectrum of PG1148+549 that appears to be associated either with an edge-on dwarf galaxy with an obvious disk (UGC 6894, z {sub gal} = 0.00283) at an impact parameter of ρ = 190 kpc or with a very faint dwarf irregular galaxy at ρ = 23 kpc, which is closer to the sightline but has a larger redshift difference (z {sub gal} = 0.00107, i.e., δv = 724 km s{sup –1}). We consider various gas/galaxy associations, including infall and outflows. Based on current theoretical models, we conclude that the absorber is most likely tracing (1) the remnants of an outflow from a previous epoch, a so-called {sup a}ncient outflow{sup ,} or (2) intergalactic gas accreting onto UGC 6894, ''cold mode'' accretion. The latter scenario is supported by H I synthesis imaging data that shows the rotation curve of the disk being codirectional with the velocity offset between UGC 6894 and the absorber, which is located almost directly along the major axis of the edge-on disk.

  9. Incidence of MgII absorbers towards Blazars and the GRB/QSO puzzle

    CERN Document Server

    Bergeron, Jacqueline; Ménard, Brice

    2010-01-01

    In order to investigate the origin of the excess of strong MgII systems towards GRB afterglows as compared to QSO sightlines, we have measured the incidence of MgII absorbers towards a third class of objects: the Blazars. This class includes the BL Lac object population for which a tentative excess of MgII systems had already been reported. We observed with FORS1 at the ESO-VLT 42 Blazars with an emission redshift 0.8 1.0 A) and weaker (0.3 < w_r(2796) < 1.0 A) MgII systems. The dependence on velocity separation with respect to the background Blazars indicates, at the ~1.5 sigma level, a potential excess for beta = v/c ~0.1. We show that biases involving dust extinction or gravitational amplification are not likely to notably affect the incidence of MgII systems towards Blazars. Finally we discuss the physical conditions required for these absorbers to be ga s entrained by the powerful Blazar jets. More realistic numerical modelling of jet-ambient gas interaction is required to reach any firm conclusion...

  10. A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. A Galaxy Sample Complete to 0.01 L* and Evidence for Environmental Effects

    CERN Document Server

    Burchett, Joseph N; Bordoloi, Rongmon; Werk, Jessica K; Prochaska, J Xavier; Tumlinson, Jason; Willmer, C N A; O'Meara, John; Katz, Neal

    2015-01-01

    We employ a blindly selected sample of low-redshift C IV absorption systems identified in spectra from the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS), combined with galaxy data from the Sloan Digital Sky Survey (SDSS), to study the metal-enriched circumgalactic medium (CGM) with ~100% completeness for galaxy luminosities L > 0.01 L* at z ~0.1 L* galaxies (7/8) than for less luminous galaxies (1/10). We also find that the occurrence of C IV absorbers depends strongly on the broader environment: 67% (8/12) of galaxies with rho < 150 kpc in regions of low galaxy density (regions with fewer than ten 0.1 L* galaxies within 1 Mpc) have affiliated C IV absorption while none (0/9) of the galaxies in denser regions show C IV within rho < 150 kpc. The reduced detection rate of C IV in denser environments persists for massive group dark matter halos. In contrast, H I is pervasive in the CGM without regard to mass or environment, although some of these Ly-alpha absorbers could arise in unrelated...

  11. STAR CLUSTER COMPLEXES AND THE HOST GALAXY IN THREE H II GALAXIES: Mrk 36, UM 408, AND UM 461

    Energy Technology Data Exchange (ETDEWEB)

    Lagos, P. [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Telles, E. [Observatorio Nacional, Rua Jose Cristino, 77, Rio de Janeiro 20921-400 (Brazil); Nigoche-Netro, A. [Instituto de Astrofisica de Andalucia (IAA), Glorieta de la Astronomia s/n, 18008 Granada (Spain); Carrasco, E. R., E-mail: plagos@astro.up.pt, E-mail: etelles@on.br, E-mail: nigoche@iaa.es, E-mail: rcarrasco@gemini.edu [Gemini Observatory/AURA, Southern Operations Center, Casilla 603, La Serena (Chile)

    2011-11-15

    We present a stellar population study of three H II galaxies (Mrk 36, UM 408, and UM 461) based on the analysis of new ground-based high-resolution near-infrared J, H, and K{sub p} broadband and Br{gamma} narrowband images obtained with Gemini/NIRI. We identify and determine the relative ages and masses of the elementary star clusters and/or star cluster complexes of the starburst regions in each of these galaxies by comparing the colors with evolutionary synthesis models that include the contribution of stellar continuum, nebular continuum, and emission lines. We found that the current star cluster formation efficiency in our sample of low-luminosity H II galaxies is {approx}10%. Therefore, most of the recent star formation is not in massive clusters. Our findings seem to indicate that the star formation mode in our sample of galaxies is clumpy, and that these complexes are formed by a few massive star clusters with masses {approx}>10{sup 4} M{sub Sun }. The age distribution of these star cluster complexes shows that the current burst started recently and likely simultaneously over short timescales in their host galaxies, triggered by some internal mechanism. Finally, the fraction of the total cluster mass with respect to the low surface brightness (or host galaxy) mass, considering our complete range in ages, is less than 1%.

  12. Atomic data for Zn II - Improving Spectral Diagnostics of Chemical Evolution in High-redshift Galaxies

    CERN Document Server

    Kisielius, Romas; Ferland, Gary J; Bogdanovich, Pavel; Som, Debopam; Lykins, Matt L

    2015-01-01

    Damped Lyman-alpha (DLA) and sub-DLA absorbers in quasar spectra provide the most sensitive tools for measuring element abundances of distant galaxies. Estimation of abundances from absorption lines depends sensitively on the accuracy of the atomic data used. We have started a project to produce new atomic spectroscopic parameters for optical/UV spectral lines using state-of-the-art computer codes employing very broad configuration interaction basis. Here we report our results for Zn II, an ion used widely in studies of the interstellar medium (ISM) as well as DLA/sub-DLAs. We report new calculations of many energy levels of Zn II, and the line strengths of the resulting radiative transitions. Our calculations use the configuration interaction approach within a numerical Hartree-Fock framework. We use both non-relativistic and quasi-relativistic one-electron radial orbitals. We have incorporated the results of these atomic calculations into the plasma simulation code Cloudy, and applied them to a lab plasma a...

  13. Atomic data for S II - Toward Better Diagnostics of Chemical Evolution in High-redshift Galaxies

    CERN Document Server

    Kisielius, Romas; Ferland, Gary J; Bogdanovich, Pavel; Lykins, Matt L

    2013-01-01

    Absorption-line spectroscopy is a powerful tool used to estimate element abundances in the nearby as well as distant universe. The accuracy of the abundances thus derived is, naturally, limited by the accuracy of the atomic data assumed for the spectral lines. We have recently started a project to perform the new extensive atomic data calculations used for optical/UV spectral lines in the plasma modeling code Cloudy using state-of-the-art quantal calculations. Here we demonstrate our approach by focussing on S II, an ion used to estimate metallicities for Milky Way interstellar clouds as well as distant damped Lyman-alpha (DLA) and sub-DLA absorber galaxies detected in the spectra of quasars and gamma-ray bursts (GRBs). We report new extensive calculations of a large number of energy levels of S II, and the line strengths of the resulting radiative transitions. Our calculations are based on the configuration interaction approach within a numerical Hartree-Fock framework, and utilize both non-ralativistic and ...

  14. Galaxy counterparts of metal-rich damped Lyα absorbers - I. The case of the z= 2.35 DLA towards Q 2222−0946

    NARCIS (Netherlands)

    Fynbo, J.P.U.; Laursen, P.; Ledoux, C.; Møller, P.; Durgapal, A.K.; Goldoni, P.; Gullberg, B.; Kaper, L.; Maund, J.; Noterdaeme, P.; Östlin, G.; Strandet, M.L.; Toft, S.; Vreeswijk, P.M.; Zafar, T.

    2010-01-01

    We have initiated a survey using the newly commissioned X-shooter spectrograph to target candidate relatively metal-rich damped Lyα absorbers (DLAs). Our rationale is that high-metallicity DLAs due to the luminosity-metallicity relation likely will have the most luminous galaxy counterparts. In

  15. Thermodynamic evolution of the cosmological baryonic gas II. Galaxy formation

    CERN Document Server

    Alimi, J M

    2004-01-01

    The problem of galaxy formation and its dependence on thermodynamic properties is addressed by using Eulerian hydrodynamic numerical simulations of large scale structure formation. Global galaxy properties are explored in simulations including gravitation, shock heating and cooling processes, and following self-consistently the chemical evolution of a primordial composition hydrogen-helium plasma without assuming collisional ionization equilibrium. The galaxy formation model is mainly based on the identification of converging dense cold gas regions. We show that the evolution at low redshift of the observed cosmic star formation rate density is reproduced, and that the galaxy-like object mass function is dominated by low-mass objects. The galaxy mass functions are well described by a two power-law Schechter function whose parameters are in good agreement with observational fits of the galaxy luminosity function. The high-mass end of the galaxy mass function includes objects formed at early epochs and residing...

  16. Galaxy Morphology - Halo Gas Connections

    CERN Document Server

    Kacprzak, G G; Steidel, C C; Kacprzak, Glenn G.; Churchill, Christopher W.; Steidel, Charles C.

    2005-01-01

    We studied a sample of 38 intermediate redshift MgII absorption-selected galaxies using (1) Keck/HIRES and VLT/UVES quasar spectra to measure the halo gas kinematics from MgII absorption profiles and (2) HST/WFPC-2 images to study the absorbing galaxy morphologies. We have searched for correlations between quantified gas absorption properties, and host galaxy impact parameters, inclinations, position angles, and quantified morphological parameters. We report a 3.2-sigma correlation between asymmetric perturbations in the host galaxy morphology and the MgII absorption equivalent width. We suggest that this correlation may indicate a connection between past merging and/or interaction events in MgII absorption-selected galaxies and the velocity dispersion and quantity of gas surrounding these galaxies.

  17. Discovery of a Damped Lya Absorber at z = 3.3 along a galaxy sight-line in the SSA22 field

    CERN Document Server

    Mawatari, K; Kousai, K; Hayashino, T; Cooke, R; Prochaska, J X; Yamada, T; Matsuda, Y

    2015-01-01

    Using galaxies as background light sources to map the Lya absorption lines is a novel approach to study Damped Lya Absorbers (DLAs). We report the discovery of an intervening z = 3.335 +- 0.007 DLA along a galaxy sight-line identified among 80 Lyman Break Galaxy (LBG) spectra obtained with our VLT/VIMOS survey in the SSA22 field. The measured DLA neutral hydrogen (HI) column density is log (NHI/cm^{-2}) = 21.68 +- 0.17. The DLA covering fraction over the extended background LBG is > 70 % (2 sigma), yielding a conservative constraint on the DLA area as > 1 kpc^2. Our search for a counterpart galaxy hosting this DLA concludes that there is no counterpart galaxy with star formation rate (SFR) larger than a few Msun yr^{-1}, ruling out an unobscured violent star formation in the DLA gas cloud. We also rule out the possibility that the host galaxy of the DLA is a passive galaxy with Mstar > 5 x 10^{10} Msun or a heavily dust-obscured galaxy with E(B-V) > 2. The DLA may coincide in a large-scale overdensity of the ...

  18. Massive Warm/Hot Galaxy Coronae as Probed by OVI, OVII and OVIII Absorbers

    CERN Document Server

    Faerman, Yakov; McKee, Christopher F

    2016-01-01

    We construct an analytic phenomenological model for extended warm/hot gaseous coronae of L* galaxies. We aim to reproduce the column densities of highly ionized oxygen ions observed in the ultraviolet and X-ray, as evidence for warm/hot gas in a wide range of temperatures and ionization states. We consider OVI data from the COS-Halos sample of galaxies in combination with the nearby OVII and OVIII absorption that we interpret as arising in an extended corona around the Milky Way. We fit these data sets with a single representative model. The gas in our model is multiphased, with hot and warm components. Each component has a (turbulent) log-normal distribution of temperatures and densities. The hot gas is traced by the OVII and OVIII and is in hydrostatic equilibrium in a Milky Way gravitational potential. The median temperature of the hot gas is $1.8*10^6$ K and the resulting mean hydrogen density is $\\sim 5*10^{-5}~cm^{-3}$, consistent with ram-pressure stripping observed in Milky Way satellites. The warm co...

  19. Astrocladistics: a phylogenetic analysis of galaxy evolution II. Formation and diversification of galaxies

    CERN Document Server

    Fraix-Burnet, D; Choler, P; Verhamme, A; Fraix-Burnet, Didier; Douzery, Emmanuel J.P.; Choler, Philippe; Verhamme, Anne

    2006-01-01

    This series of papers is intended to evaluate astrocladistics in reconstructing phylogenies of galaxies. The objective of this second paper is to formalize the concept of galaxy formation and to identify the processes of diversification. We show that galaxy diversity can be expected to organize itself in a hierarchy. In order to better understand the role of mergers, we have selected a sample of 43 galaxies from the GALICS database built from simulations with a hybrid model for galaxy formation studies. These simulated galaxies, described by 119 characters and considered as representing still undefined classes, have experienced different numbers of merger events during evolution. Our cladistic analysis yields a robust tree that proves the existence of a hierarchy. Mergers, like interactions (not taken into account in the GALICS simulations), are probably a strong driver for galaxy diversification. Our result shows that mergers participate in a branching type of evolution, but do not seem to play the role of a...

  20. Close neighbors of Markarian galaxies. II. Statistics and discussions

    CERN Document Server

    Nazaryan, T A; Hakobyan, A A; McLean, B J; Kunth, D

    2013-01-01

    According to the database from the first paper, we select 180 pairs with dV < 800 km/s and Dp < 60 kpc containing Markarian (MRK) galaxies. We study the dependence of galaxies integral parameters, star-formation (SF) and active galactic nuclei (AGN) properties on kinematics of pairs, their structure and large-scale environments. Following main results were obtained: projected radial separation Dp between galaxies correlates with the perturbation level P of the pairs. Both parameters do not correlate with line-of-sight velocity difference dV of galaxies. Dp and P are better measures of interaction strength than dV. The latter correlates with the density of large-scale environment and with the morphologies of galaxies. Both galaxies in a pair are of the same nature, the only difference is that MRK galaxies are usually brighter than their neighbors in average by 0.9 mag. Specific star formation rates (SSFR) of galaxies in pairs with smaller Dp or dV is in average 0.5 dex higher than that of galaxies in pai...

  1. [C II] emission in z ˜ 6 strongly lensed, star-forming galaxies

    Science.gov (United States)

    Knudsen, Kirsten K.; Richard, Johan; Kneib, Jean-Paul; Jauzac, Mathilde; Clément, Benjamin; Drouart, Guillaume; Egami, Eiichi; Lindroos, Lukas

    2016-10-01

    The far-infrared fine-structure line [C II] at 1900.5 GHz is known to be one of the brightest cooling lines in local galaxies, and therefore it has been suggested to be an efficient tracer for star formation in very high redshift galaxies. However, recent results for galaxies at z > 6 have yielded numerous non-detections in star-forming galaxies, except for quasars and submillimetre galaxies. We report the results of ALMA observations of two lensed, star-forming galaxies at z = 6.029 and z = 6.703. The galaxy A383-5.1 (star formation rate [SFR] of 3.2 M⊙ yr-1 and magnification of μ = 11.4 ± 1.9) shows a line detection with L_[C II] = 8.9× 106 L⊙, making it the lowest L_[C II] detection at z > 6. For MS0451-H (SFR = 0.4 M⊙ yr-1 and μ = 100 ± 20) we provide an upper limit of L_[C II] 6; however, other effects could also play a role in terms of decreasing L[CII]. The detection of A383-5.1 is encouraging and suggests that detections are possible, but much fainter than initially predicted.

  2. Star Formation in Isolated Disk Galaxies. II. Schmidt Laws and Star Formation Efficiency

    CERN Document Server

    Li, Y; Klessen, R S; Li, Yuexing; Low, Mordecai-Mark Mac

    2005-01-01

    We model star formation in a wide range of isolated disk galaxies, using a three-dimensional, smoothed particle hydrodynamics code. The model galaxies include a dark matter halo and a disk of stars and isothermal gas. Absorbing sink particles are used to directly measure the mass of gravitationally collapsing gas. Below the density at which they are inserted, the collapsing gas is fully resolved. The star formation rate measured in our models declines exponentially with time. Radial profiles of atomic and molecular gas and star formation rate reproduce observed behavior. We derive from our models and discuss both the global and local Schmidt laws for star formation: power-law relations between surface densities of gas and star formation rate. The global Schmidt law observed in disk galaxies is quantitatively reproduced by our models. We find that the surface density of star formation rate directly correlates with the strength of local gravitational instability. The local Schmidt laws of individual galaxies in...

  3. Properties of QSO Metal-line Absorption Systems at High Redshifts: Nature and Evolution of the Absorbers and New Evidence on Escape of Ionizing Radiation from Galaxies

    Science.gov (United States)

    Boksenberg, Alec; Sargent, Wallace L. W.

    2015-05-01

    Using Voigt-profile-fitting procedures on Keck High Resolution Spectrograph spectra of nine QSOs, we identify 1099 C IV absorber components clumped in 201 systems outside the Lyman forest over 1.6 model ionization predictions for absorbers exposed to the metagalactic ionizing radiation background augmented by proximity radiation from their associated galaxies and find that the generally accepted means of radiative escape by transparent channels from the internal star-forming sites is spectrally not viable for our stronger absorbers. We develop an active scenario based on runaway stars with resulting changes in the efflux of radiation that naturally enable the needed spectral convergence, and in turn provide empirical indicators of morphological evolution in the associated galaxies. Together with a coexisting population of relatively compact galaxies indicated by the weaker absorbers in our sample, the collective escape of radiation is sufficient to maintain the intergalactic medium ionized over the full range 1.9 Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  4. A search for HI 21cm absorption in strong MgII absorbers in the redshift desert

    CERN Document Server

    Kanekar, N; Ellison, S L; Chengalur, J N

    2009-01-01

    We report results from a deep search for redshifted HI 21cm absorption in 55 strong MgII$\\lambda$2796 absorbers (having $W (MgII) > 0.5 \\AA$) at intermediate redshifts, $0.58 3\\sigma$ significance in 32 other MgII absorbers, with 26 of these providing strong upper limits to the HI 21cm optical depth, $\\tau_{3\\sigma} [800 \\times f]$ K (where $f$ is the covering factor), if the HI column density is $\\ge 2 \\times 10^{20}$ cm$^{-2}$, i.e. if the absorber is a damped Lyman-$\\alpha$ system (DLA). Data on the remaining 13 systems of the sample were affected by radio frequency interference and were hence not useful. Excluding "associated" systems (within 3000 km/s of the quasar redshift), the detection rate of HI 21cm absorption in strong MgII absorbers is $x_{\\rm 21,MgII} ({\\bar z} = 1.1) = 25^{+11}_{-8}$%, at a $3\\sigma$ optical depth sensitivity of $\\sim 0.013$ per 10 km/s. Comparing the detection rates of HI 21cm and damped Lyman-$\\alpha$ absorption in strong MgII absorber samples yields a detection rate of HI ...

  5. Probing low-redshift galaxies using quasar absorption lines with an emphasis on Ca II absorption

    Science.gov (United States)

    Sardane, Gendith M.

    2016-05-01

    We searched for intervening CaII absorption in nearly 95,000 quasar spectra with i≤20 from the Sloan Digital Sky Survey(SDSS) data releases DR7+DR9. Our identification of >400 CaII systems is the largest compilation of CaII absorbers in a blind search. (Abstract shortened by ProQuest.).

  6. Halo Gas and Galaxy Disk Kinematics of a Volume-Limited Sample of MgII Absorption-Selected Galaxies at z~0.1

    CERN Document Server

    Kacprzak, G G; Barton, E J; Cooke, J

    2011-01-01

    We have directly compared MgII halo gas kinematics to the rotation velocities derived from emission/absorption lines of the associated host galaxies. Our 0.096galaxies, with impact parameters of 12-90 kpc from background quasars sight-lines, associated with 11 MgII absorption systems with MgII equivalent widths 0.3< W_r(2796)<2.3A. For only 5/13 galaxies, the absorption resides to one side of the galaxy systemic velocity and trends to align with one side of the galaxy rotation curve. The remainder have absorption that spans both sides of the galaxy systemic velocity. These results differ from those at z~0.5, where 74% of the galaxies have absorption residing to one side of the galaxy systemic velocity. For all the z~0.1 systems, simple extended disk-like rotation models fail to reproduce the full MgII velocity spread, implying other dynamical processes contribute to the MgII kinematics. In fact 55% of the galaxies are "counter-rotating" with respect ...

  7. The Physical Conditions of Intermediate Redshift MgII Absorbing Clouds from Voigt Profile Analysis

    CERN Document Server

    Churchill, C W; Charlton, J; Churchill, Chris; Vogt, Steven; Charlton, Jane

    2003-01-01

    [Slightly Abridged] We present a detailed statistical analysis of the column densities, N, and Doppler parameters, b, of MgII absorbing clouds at redshifts 0.4~5 km/s for MgII and FeII and ~7 km/s for MgI. The clouds are consistent with being thermally broadened, with temperatures in the 30-40,000K range. (4) A two-component Gaussian model to the velocity two-point correlation function yielded velocity dispersions of 54 km/s and 166 km/s. The narrow component has roughly twice the amplitude of the broader component. The width and amplitude of the broader component decreases as equivalent width increases. (5) From photoionization models we find that the column density ratios are most consistent with photoionization by the extragalactic background, as opposed to stars. Based upon N(MgI)/N(MgII), it appears that at least two-phase ionization models are required to explain the data.

  8. Fundamental properties of Fanaroff-Riley type II radio galaxies investigated via Monte Carlo simulations

    NARCIS (Netherlands)

    Kapińska, A.D.; Uttley, P.; Kaiser, C.

    2012-01-01

    Radio galaxies and quasars are among the largest and most powerful single objects known and are believed to have had a significant impact on the evolving Universe and its large-scale structure. We explore the intrinsic and extrinsic properties of the population of Fanaroff-Riley type II (FR II) obje

  9. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics

    NARCIS (Netherlands)

    Harwood, Jeremy J.; Croston, Judith H.; Intema, Huib T.; Stewart, Adam J.; Ineson, Judith; Hardcastle, Martin J.; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K.; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W.

    2016-01-01

    Due to their steep spectra, low-frequency observations of Fanaroff-Riley type II (FR II) radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at

  10. Spectroscopic Confirmation of the Dwarf Galaxies Hydra II and Pisces II and the Globular Cluster Laevens 1

    CERN Document Server

    Kirby, Evan N; Cohen, Judith G

    2015-01-01

    We present Keck/DEIMOS spectroscopy of stars in the recently discovered Milky Way satellites Hydra II, Pisces II, and Laevens 1. We measured a velocity dispersion of 5.4 (+3.6 -2.4) km/s for Pisces II, but we did not resolve the velocity dispersions of Hydra II or Laevens 1. We marginally resolved the metallicity dispersions of Hydra II and Pisces II but not Laevens 1. Furthermore, Hydra II and Pisces II obey the luminosity-metallicity relation for Milky Way dwarf galaxies ( = -2.02 +/- 0.08 and -2.45 +/- 0.07, respectively), whereas Laevens 1 does not ( = -1.68 +/- 0.05). The kinematic and chemical properties suggest that Hydra II and Pisces II are dwarf galaxies, and Laevens 1 is a globular cluster. We determined that two of the previously observed blue stars near the center of Laevens 1 are not members of the cluster. A third blue star has ambiguous membership. If it is a member, we suggest that it could be a Type II Cepheid variable. Hydra II has a radial velocity = 303.1 +/- 1.4 km/s, similar to the lea...

  11. Studying the Interstellar Medium of H II/BCD Galaxies Using IFU Spectroscopy

    Directory of Open Access Journals (Sweden)

    Patricio Lagos

    2013-01-01

    Full Text Available We review the results from our studies, and previous published work, on the spatially resolved physical properties of a sample of H ii/BCD galaxies, as obtained mainly from integral-field unit spectroscopy with Gemini/GMOS and VLT/VIMOS. We confirm that, within observational uncertainties, our sample galaxies show nearly spatially constant chemical abundances similar to other low-mass starburst galaxies. They also show He ii  λ4686 emission with the properties being suggestive of a mix of excitation sources and with Wolf-Rayet stars being excluded as the primary ones. Finally, in this contribution, we include a list of all H ii/BCD galaxies studied thus far with integral-field unit spectroscopy.

  12. FR II radio galaxies at low frequencies - II. Spectral ageing and source dynamics

    Science.gov (United States)

    Harwood, Jeremy J.; Hardcastle, Martin J.; Morganti, Raffaella; Croston, Judith H.; Brüggen, Marcus; Brunetti, Gianfranco; Röttgering, Huub J. A.; Shulevski, Aleksander; White, Glenn J.

    2017-07-01

    In this paper, the second in a series investigating Fanaroff-Riley type II (FR II) radio galaxies at low frequencies, we use LOw Frequency ARray (LOFAR) and Very Large Array (VLA) observations between 117 and 456 MHz, in addition to archival data, to determine the dynamics and energetics of two radio galaxies, 3C 452 and 3C 223, by fitting spectral ageing models on small spatial scales. We provide improved measurements for the physical extent of the two sources, including a previously unknown low surface brightness extension to the northern lobe of 3C 223, and revised energetics based on these values. We find spectral ages of 77.05^{+9.22}_{-8.74} and 84.96^{+15.02}_{-13.83} Myr for 3C 452 and 3C 223, respectively, suggesting a characteristic advance speed for the lobes of around 1 per cent of the speed of light. For 3C 452, we show that, even for a magnetic field strength not assumed to be in equipartition, a disparity of a factor of approximately 2 exists between the spectral age and that determined from a dynamical standpoint. We confirm that the injection index of both sources (as derived from the lobe emission) remains steeper than classically assumed values, even when considered on well-resolved scales at low frequencies. However, we find an unexpected sharp discontinuity between the spectrum of the hotspots and the surrounding lobe emission. We suggest that this discrepancy is a result of the absorption of hotspot emission and/or non-homogeneous and additional acceleration mechanisms; as such, hotspots should not be used in the determination of the underlying initial electron energy distribution.

  13. Complete Element Abundances of Nine Stars in the r-process Galaxy Reticulum II

    Science.gov (United States)

    Ji, Alexander P.; Frebel, Anna; Simon, Joshua D.; Chiti, Anirudh

    2016-10-01

    We present chemical abundances derived from high-resolution Magellan/Magellan Inamori Kyocera Echelle spectra of the nine brightest known red giant members of the ultra-faint dwarf galaxy Reticulum II (Ret II). These stars span the full metallicity range of Ret II (‑3.5 date. The other two stars are the most metal-poor stars in the system ([Fe/H] up to the iron peak are otherwise similar to abundances of stars in the halo and in other ultra-faint dwarf galaxies. However, the scatter in abundance ratios is large enough to suggest that inhomogeneous metal mixing is required to explain the chemical evolution of this galaxy. The presence of low amounts of neutron-capture elements in other ultra-faint dwarf galaxies may imply the existence of additional r-process sites besides the source of r-process elements in Ret II. Galaxies like Ret II may be the original birth sites of r-process enhanced stars now found in the halo. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  14. Simulating galaxy Clusters -II: global star formation histories and galaxy populations

    CERN Document Server

    Romeo, A D; Sommer-Larsen, J

    2004-01-01

    Cosmological (LambdaCDM) TreeSPH simulations of the formation and evolution of galaxy groups and clusters have been performed. The simulations invoke star formation, chemical evolution with non-instantaneous recycling, metal dependent radiative cooling, strong star burst and (optionally) AGN driven galactic super winds, effects of a meta-galactic UV field and thermal conduction. The properties of the galaxy populations in two clusters, one Virgo-like (T~3 keV) and one (sub) Coma-like (T~6 keV), are discussed. The global star formation rates of the cluster galaxies are found to decrease very significantly with time from redshift z=2 to 0, in agreement with observations. The total K-band luminosity of the cluster galaxies correlates tightly with total cluster mass, and for models without additional AGN feedback, the zero point of the relation matches the observed one fairly well. The match to observed galaxy luminosity functions is reasonable, except for a deficiency of bright galaxies (M_B < -20), which bec...

  15. DISCOVERY OF A DAMPED Lyα ABSORBER AT z = 3.3 ALONG A GALAXY SIGHT-LINE IN THE SSA22 FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Mawatari, K.; Inoue, A. K. [College of General Education, Osaka Sangyo University, 3-1-1, Nakagaito, Daito, Osaka, 574-8530 (Japan); Kousai, K.; Hayashino, T. [Research Center for Neutrino Science, General School of Science, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 (Japan); Cooke, R.; Prochaska, J. X. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Yamada, T. [Astronomical Institute, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 (Japan); Matsuda, Y., E-mail: mawatari@las.osaka-sandai.ac.jp [National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan)

    2016-02-01

    Using galaxies as background light sources to map the Lyα absorption lines is a novel approach to study Damped Lyα Absorbers (DLAs). We report the discovery of an intervening z = 3.335 ± 0.007 DLA along a galaxy sight-line identified among 80 Lyman Break Galaxy (LBG) spectra obtained with our Very Large Telescope/Visible Multi-Object Spectrograph survey in the SSA22 field. The measured DLA neutral hydrogen (H i) column density is log(N{sub H} {sub i}/cm{sup −2}) = 21.68 ± 0.17. The DLA covering fraction over the extended background LBG is >70% (2σ), yielding a conservative constraint on the DLA area of ≳1 kpc{sup 2}. Our search for a counterpart galaxy hosting this DLA concludes that there is no counterpart galaxy with star formation rate larger than a few M{sub ⊙} yr{sup −1}, ruling out an unobscured violent star formation in the DLA gas cloud. We also rule out the possibility that the host galaxy of the DLA is a passive galaxy with M{sub *} ≳ 5 × 10{sup 10}M{sub ⊙} or a heavily dust-obscured galaxy with E(B − V) ≳ 2. The DLA may coincide with a large-scale overdensity of the spectroscopic LBGs. The occurrence rate of the DLA is compatible with that of DLAs found in QSO sight-lines.

  16. Chandra view of the dynamically young cluster of galaxies A1367 II. point sources

    CERN Document Server

    Sun, M

    2002-01-01

    A 40 ks \\emph{Chandra} ACIS-S observation of the dynamically young cluster A1367 yields new insights on X-ray emission from cluster member galaxies. We detect 59 point-like sources in the ACIS field, of which 8 are identified with known cluster member galaxies. Thus in total 10 member galaxies are detected in X-rays when three galaxies discussed in paper I (Sun & Murray 2002; NGC 3860 is discussed in both papers) are included. The superior spatial resolution and good spectroscopy capability of \\chandra allow us to constrain the emission nature of these galaxies. Central nuclei, thermal halos and stellar components are revealed in their spectra. Four new low luminosity nuclei (LLAGN) are found, including an absorbed one (NGC 3861). This discovery makes the LLAGN/AGN content in this part of A1367 very high ($\\sim$ 20%). Thermal halos with temperatures around 0.5 - 0.8 keV are revealed in the spectra of two elliptical galaxies NGC 3842 and NGC 3837, which suggests that galactic coronae can survive in cluster...

  17. The Arecibo Galaxy Environment Survey VI : The Virgo Cluster (II)

    CERN Document Server

    Taylor, R; Auld, R; Minchin, R F; Smith, R

    2012-01-01

    We present 21 cm observations of a 5 x degree region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 13 cluster members are detected, together with 36 objects in the background. We compare and contrast the results from this area with a larger 10 x degree region. We combine the two data sets to produce an HI mass function, which shows a higher detection rate at low masses (but finds fewer massive galaxies) than less sensitive wider-area surveys, such as ALFALFA. We find that the HI-detected galaxies are distributed differently to the non-detections, both spatially and in velocity, providing further evidence that the cluster is still assembling. We use the Tully-Fisher relation to examine the possibility of morphological evolution. We find that highly deficient galaxies, as well as some early-type galaxies, have much lower velocity widths than the Tully-Fisher relation predicts, indicating gas loss via ram pressure stripping. We also find that HI detections without optical count...

  18. THE CARNEGIE-IRVINE GALAXY SURVEY. II. ISOPHOTAL ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Li Zhaoyu [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Ho, Luis C. [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697-4575 (United States); Peng, Chien Y. [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)

    2011-12-01

    The Carnegie-Irvine Galaxy Survey (CGS) is a comprehensive investigation of the physical properties of a complete, representative sample of 605 bright (B{sub T} {<=} 12.9 mag) galaxies in the southern hemisphere. This contribution describes the isophotal analysis of the broadband (BVRI) optical imaging component of the project. We pay close attention to sky subtraction, which is particularly challenging for some of the large galaxies in our sample. Extensive crosschecks with internal and external data confirm that our calibration and sky subtraction techniques are robust with respect to the quoted measurement uncertainties. We present a uniform catalog of one-dimensional radial profiles of surface brightness and geometric parameters, as well as integrated colors and color gradients. Composite profiles highlight the tremendous diversity of brightness distributions found in disk galaxies and their dependence on Hubble type. A significant fraction of S0 and spiral galaxies exhibit non-exponential profiles in their outer regions. We perform Fourier decomposition of the isophotes to quantify non-axisymmetric deviations in the light distribution. We use the geometric parameters, in conjunction with the amplitude and phase of the m = 2 Fourier mode, to identify bars and quantify their size and strength. Spiral arm strengths are characterized using the m = 2 Fourier profiles and structure maps. Finally, we utilize the information encoded in the m = 1 Fourier profiles to measure disk lopsidedness. The databases assembled here and in Paper I lay the foundation for forthcoming scientific applications of CGS.

  19. Fundamental parameters of FR II radio galaxies and their impact on groups and clusters' environments

    CERN Document Server

    Kapinska, Anna D

    2012-01-01

    Radio galaxies are among the largest and most powerful single objects known and are found at variety of redshifts, hence they are believed to have had a significant impact on the evolving Universe. Their relativistic jets inject considerable amounts of energy into the environments in which the sources reside; thus the knowledge of the fundamental properties (such as kinetic luminosities, lifetimes and ambient gas densities) of these sources is crucial for understanding AGN feedback in galaxy clusters. In this work, we explore the intrinsic and extrinsic fundamental properties of Fanaroff-Riley II (FR II) objects through the construction of multidimensional Monte Carlo simulations which use complete, flux limited radio catalogues and semi-analytical models of FR IIs' time evolution to create artificial samples of radio galaxies. This method allows us to set better limits on the confidence intervals of the intrinsic and extrinsic fundamental parameters and to investigate the total energy produced and injected t...

  20. EIG - II. Intriguing characteristics of the most extremely isolated galaxies

    Science.gov (United States)

    Spector, O.; Brosch, N.

    2017-07-01

    We have selected a sample of 41 extremely isolated galaxies (EIGs) from the local Universe using both optical and H i Arecibo Legacy Fast ALFA survey redshifts. Narrow-band H α and wide-band imaging along with public data were used to derive star formation rates (SFRs), star formation histories and morphological classifications for the EIGs. We have found that the extreme isolation of the EIGs does not affect considerably their star formation compared to field galaxies. EIGs are typically 'blue cloud' galaxies that fit the 'main sequence of star-forming galaxies' and may show asymmetric star formation and strong compact star-forming regions. We discovered surprising environmental dependences of the H i content, {M} _{H I}, and of the morphological type of EIGs; the most isolated galaxies (of subsample EIG-1) have lower {M} _{H I} on average (with 2.5σ confidence) and a higher tendency to be early types (with 0.94 confidence) compared to the less isolated galaxies of subsample EIG-2. To the best of our knowledge, this is the first study that finds an effect in which an isolated sample shows a higher fraction of early types compared to a less isolated sample. Both early-type and late-type EIGs follow the same colour-to-M*, SFR-to-M* (main sequence) and {M} _{H I}-to-M* relations. This indicates that the mechanisms and factors governing star formation, colour and the {M} _{H I}-to-M* relation are similar in early-type and late-type EIGs, and that the morphological type of EIGs is not governed by their {M} _{H I} content, colour or SFR.

  1. Mergers in Galaxy Groups. II. The Fundamental Plane of Elliptical Galaxies

    CERN Document Server

    Taranu, Dan S; Yee, H K C

    2014-01-01

    Observations consistently show that elliptical galaxies follow a tight "fundamental plane" scaling relation between size, mean surface brightness and velocity dispersion, with the form R $\\propto {\\sigma}^a {\\mu}^b$. This relation not only has very small (<0.05 dex) intrinsic scatter, but also has significantly different coefficients from the expect virial scaling (a "tilt"). We analyze hundreds of simulations of elliptical galaxies formed from mergers of spiral galaxies in groups to determine if the fundamental plane can emerge from multiple, mostly minor and hierarchical collisionless mergers. We find that these simulated ellipticals lie on a similar fundamental plane with a~1.7 and b~0.3. The scatter about this plane is even smaller than observed, while the tilt is in the correct sense, although a is larger than for typical observations. This demonstrates that collisionless mergers can contribute significantly to the tilt of the fundamental plane, contrary to previous claims that only gas dissipation co...

  2. Observations of Ultraluminous Infrared Galaxies with the Infrared Spectrograph on the Spitzer Space Telescope II: The IRAS Bright Galaxy Sample

    CERN Document Server

    Armus, L; Bernard-Salas, J; Spoon, H W W; Marshall, J A; Higdon, S J U; Desai, V; Teplitz, H I; Hao, L; Devost, D; Brandl, B R; Wu, Y; Sloan, G C; Soifer, B T; Houck, J R; Herter, T L

    2006-01-01

    We present spectra taken with the Infrared Spectrograph on Spitzer covering the 5-38 micron region of the ten Ultraluminous Infrared Galaxies (ULIRGs) found in the IRAS Bright Galaxy Sample. Among the BGS ULIRGs, we find a factor of 50 spread in the rest-frame mid to far-infrared spectral slope. The 9.7 micron silicate optical depths range from less than 0.4 more than 4.2, implying line of sight extinctions of A(V) ~ 8 - 78 mag. There is evidence for water ice and hydrocarbon absorption and C2H2 and HCN absorption features in four and possibly six of the 10 BGS ULIRGs, indicating shielded molecular clouds and a warm, dense ISM. We have detected [NeV] emission in three of the ten BGS ULIRGs, at flux levels of 5-18E-14 erg/cm^2/sec and [NeV] 14.3/[NeII] 12.8 line flux ratios of 0.12-0.85. The remaining BGS ULIRGs have limits on their [NeV]/[NeII] line flux ratios which range from less than 0.15 to less than 0.01. Among the BGS ULIRGs, the AGN fractions implied by either the [NeV]/[NeII] or [OIV]/[NeII] line flu...

  3. 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...

  4. nIFTy galaxy cluster simulations II: radiative models

    CSIR Research Space (South Africa)

    Sembolini, F

    2016-04-01

    Full Text Available We have simulated the formation of a massive galaxy cluster (M(supcrit)(sub200) = 1.1×10(sup15)h(sup-1)M) in a CDM universe using 10 different codes (RAMSES, 2 incarnations of AREPO and 7 of GADGET), modeling hydrodynamics with full radiative...

  5. Fine-Structure FeII* Emission and Resonant MgII Emission in z = 1 Star-Forming Galaxies

    CERN Document Server

    Kornei, K A; Martin, C L; Coil, A L; Lotz, J M; Weiner, B J

    2013-01-01

    We present a study of the prevalence, strength, and kinematics of ultraviolet FeII and MgII emission lines in 212 star-forming galaxies at z = 1 selected from the DEEP2 survey. We find FeII* emission in composite spectra assembled on the basis of different galaxy properties, indicating that FeII* emission is prevalent at z = 1. In these composites, FeII* emission is observed at roughly the systemic velocity. At z = 1, we find that the strength of FeII* emission is most strongly modulated by dust attenuation, and is additionally correlated with redshift, star-formation rate, and [OII] equivalent width, such that systems at higher redshifts with lower dust levels, lower star-formation rates, and larger [OII] equivalent widths show stronger FeII* emission. We detect MgII emission in at least 15% of the individual spectra and we find that objects showing stronger MgII emission have higher specific star-formation rates, smaller [OII] linewidths, larger [OII] equivalent widths, lower dust attenuations, and lower st...

  6. Halo Gas and Galaxy Disk Kinematics Derived from Observations and LCDM Simulations of MgII Absorption Selected Galaxies at Intermediate Redshift

    CERN Document Server

    Kacprzak, G G; Ceverino, D; Steidel, C C; Klypin, A; Murphy, M T

    2009-01-01

    We obtained ESI/Keck rotation curves of 10 MgII absorption selected galaxies (0.3 < z < 1.0) for which we have WFPC-2/HST images and high resolution HIRES/Keck and UVES/VLT quasar spectra of the MgII absorption profiles. We perform a kinematic comparison of these galaxies and their associated halo MgII absorption. For all 10 galaxies, the majority of the absorption velocities lie in the range of the observed galaxy rotation velocities. In 7/10 cases, the absorption velocities reside fully to one side of the galaxy systemic velocity and usually align with one arm of the rotation curve. In all cases, a constant rotating thick-disk model poorly reproduces the full spread of observed MgII absorption velocities when reasonably realistic parameters are employed. In 2/10 cases, the galaxy kinematics, star formation surface densities, and absorption kinematics have a resemblance to those of high redshift galaxies showing strong outflows. We find that MgII absorption velocity spread and optical depth distributio...

  7. A massive, quiescent, population II galaxy at a redshift of 2.1

    Science.gov (United States)

    Kriek, Mariska; Conroy, Charlie; van Dokkum, Pieter G.; Shapley, Alice E.; Choi, Jieun; Reddy, Naveen A.; Siana, Brian; van de Voort, Freeke; Coil, Alison L.; Mobasher, Bahram

    2016-12-01

    Unlike spiral galaxies such as the Milky Way, the majority of the stars in massive elliptical galaxies were formed in a short period early in the history of the Universe. The duration of this formation period can be measured using the ratio of magnesium to iron abundance ([Mg/Fe]) in spectra, which reflects the relative enrichment by core-collapse and type Ia supernovae. For local galaxies, [Mg/Fe] probes the combined formation history of all stars currently in the galaxy, including younger and metal-poor stars that were added during late-time mergers. Therefore, to directly constrain the initial star-formation period, we must study galaxies at earlier epochs. The most distant galaxy for which [Mg/Fe] had previously been measured is at a redshift of z ≈ 1.4, with [Mg/Fe] = . A slightly earlier epoch (z ≈ 1.6) was probed by combining the spectra of 24 massive quiescent galaxies, yielding an average [Mg/Fe] = 0.31 ± 0.12 (ref. 7). However, the relatively low signal-to-noise ratio of the data and the use of index analysis techniques for both of these studies resulted in measurement errors that are too large to allow us to form strong conclusions. Deeper spectra at even earlier epochs in combination with analysis techniques based on full spectral fitting are required to precisely measure the abundance pattern shortly after the major star-forming phase (z > 2). Here we report a measurement of [Mg/Fe] for a massive quiescent galaxy at a redshift of z = 2.1, when the Universe was three billion years old. With [Mg/Fe] = 0.59 ± 0.11, this galaxy is the most Mg-enhanced massive galaxy found so far, having twice the Mg enhancement of similar-mass galaxies today. The abundance pattern of the galaxy is consistent with enrichment exclusively by core-collapse supernovae and with a star-formation timescale of 0.1 to 0.5 billion years—characteristics that are similar to population II stars in the Milky Way. With an average past star

  8. The nature of composite LINER/H II galaxies as revealed from high-resolution VLA observations

    NARCIS (Netherlands)

    Filho, ME; Barthel, PD; Ho, LC

    2000-01-01

    A sample of 37 nearby galaxies displaying composite LINER/H II and pure H II spectra was observed with the VLA in an investigation of the nature of their weak radio emission. The resulting radio contour maps overlaid on optical galaxy images are presented here, together with an extensive literature

  9. Physical and Morphological Properties of [O II] Emitting Galaxies in the HETDEX Pilot Survey

    CERN Document Server

    Bridge, Joanna S; Ciardullo, Robin; Hagen, Alex; Zeimann, Greg; Malz, A I; Acquaviva, Viviana; Schneider, Donald P; Drory, Niv; Gebhardt, Karl; Jogee, Shardha

    2014-01-01

    The Hobby-Eberly Dark Energy Experiment pilot survey identified 284 [O II] 3727 emitting galaxies in a 169 square-arcminute field of sky in the redshift range 0 < z < 0.57. This line flux limited sample provides a bridge between studies in the local universe and higher-redshift [O II] surveys. We present an analysis of the star formation rates (SFRs) of these galaxies as a function of stellar mass as determined via spectral energy distribution fitting. The [O II] emitters fall on the "main sequence" of star-forming galaxies with SFR decreasing at lower masses and redshifts. However, the slope of our relation is flatter than that found for most other samples, a result of the metallicity dependence of the [O II] star formation rate indicator. The mass specific SFR is higher for lower mass objects, supporting the idea that massive galaxies formed more quickly and efficiently than their lower mass counterparts. This is confirmed by the fact that the equivalent widths of the [O II] emission lines trend small...

  10. 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.

  11. AGN Jet-induced Feedback in Galaxies. II. Galaxy colours from a multicloud simulation

    CERN Document Server

    Tortora, C; Kaviraj, S; Silk, J; Romeo, A D; Becciani, U

    2009-01-01

    We study the feedback from an AGN on stellar formation within its host galaxy, mainly using one high resolution numerical simulation of the jet propagation within the interstellar medium of an early-type galaxy. In particular, we show that in a realistic simulation where the jet propagates into a two-phase ISM, star formation can initially be slightly enhanced and then, on timescales of few million years, rapidly quenched, as a consequence both of the high temperatures attained and of the reduction of cloud mass (mainly due to Kelvin-Helmholtz instabilities). We then introduce a model of (prevalently) {\\em negative} AGN feedback, where an exponentially declining star formation is quenched, on a very short time scale, at a time t_AGN, due to AGN feedback. Using the Bruzual & Charlot (2003) population synthesis model and our star formation history, we predict galaxy colours from this model and match them to a sample of nearby early-type galaxies showing signs of recent episodes of star formation (Kaviraj et...

  12. VLT\\/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies II. Implications for Understanding Galaxy Evolution

    CERN Document Server

    Tolstoy, E; Shetrone, M; Primas, F; Hill, V; Szeifert, A K T; Tolstoy, Eline

    2003-01-01

    We have used UVES on VLT-UT2 to take spectra of 15 individual red giant stars in the centers of four nearby dwarf spheroidal galaxies: Sculptor, Fornax, Carina and Leo I. We measure the abundance variations of numerous elements in these low mass stars with a range of ages (1-15Gyr old). This means that we can effectively measure the chemical evolution of these galaxies WITH TIME. Our results show a significant spread in metallicity with age, but an overall trend consistent with what might be expected from a closed (or perhaps leaky) box chemical evolution scenario over the last 10-15Gyr. We notice that each of these galaxies show broadly similar abundance patterns for all elements measured. This suggests a fairly uniform progression of chemical evolution with time, despite quite a large range of star formation histories. It seems likely that these galaxies had similar initial conditions, and evolve in a similar manner with star formation occurring at a uniformly low rate, even if at different times. With our ...

  13. VLT/UVES abundances in four nearby dwarf spheroidal galaxies. II. Implications for understanding galaxy evolution

    NARCIS (Netherlands)

    Tolstoy, E; Venn, KA; Shetrone, M; Primas, F; Hill, [No Value; Kaufer, A; Szeifert, T

    2003-01-01

    We have used the Ultraviolet Visual-Echelle Spectrograph (UVES) on Kueyen (UT2) of the Very Large Telescope to take spectra of 15 individual red giant stars in the centers of four nearby dwarf spheroidal galaxies (dSph's) : Sculptor, Fornax, Carina, and Leo I. We measure the abundance variations of

  14. Stellar Kinematics and Metallicities in the Ultra-faint Dwarf Galaxy Reticulum II

    Science.gov (United States)

    Simon, J. D.; Drlica-Wagner, A.; Li, T. S.; Nord, B.; Geha, M.; Bechtol, K.; Balbinot, E.; Buckley-Geer, E.; Lin, H.; Marshall, J.; Santiago, B.; Strigari, L.; Wang, M.; Wechsler, R. H.; Yanny, B.; Abbott, T.; Bauer, A. H.; Bernstein, G. M.; Bertin, E.; Brooks, D.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; D'Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Dodelson, S.; Cunha, C. E.; Estrada, J.; Evrard, A. E.; Fausti Neto, A.; Fernandez, E.; Finley, D. A.; Flaugher, B.; Frieman, J.; Gaztanaga, E.; Gerdes, D.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Maia, M. A. G.; March, M.; Martini, P.; Miller, C. J.; Miquel, R.; Ogando, R.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Schubnell, M.; Sevilla, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Tucker, D.; Vikram, V.; Walker, A. R.; Wester, W.; DES Collaboration

    2015-07-01

    We present Magellan/M2FS, Very Large Telescope/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity of 62.8+/- 0.5 {km} {{{s}}}-1 and a velocity dispersion of 3.3+/- 0.7 {km} {{{s}}}-1. The mass-to-light ratio of Ret II within its half-light radius is 470+/- 210 {M}⊙ /{L}⊙ , demonstrating that it is a strongly dark matter-dominated system. Despite its spatial proximity to the Magellanic Clouds, the radial velocity of Ret II differs from that of the LMC and SMC by 199 and 83 {km} {{{s}}}-1, respectively, suggesting that it is not gravitationally bound to the Magellanic system. The likely member stars of Ret II span 1.3 dex in metallicity, with a dispersion of 0.28 ± 0.09 dex, and we identify several extremely metal-poor stars with {{[Fe/H]}}\\lt -3. In combination with its luminosity, size, and ellipticity, these results confirm that Ret II is an ultra-faint dwarf galaxy. With a mean metallicity of {{[Fe/H]}}=-2.65+/- 0.07, Ret II matches Segue 1 as the most metal-poor galaxy known. Although Ret II is the third-closest dwarf galaxy to the Milky Way, the line-of-sight integral of the dark matter density squared is {{log}}10(J)=18.8+/- 0.6 {GeV}{ }2 {{cm}}-5 within 0.°2, indicating that the predicted gamma-ray flux from dark matter annihilation in Ret II is lower than that of several other dwarf galaxies. Based on data obtained from the ESO Science Archive Facility under request number 157689.

  15. Measures of galaxy environment -- II. Rank-ordered mark correlations

    CERN Document Server

    Skibba, Ramin A; Croton, Darren J; Muldrew, Stuart I; Abbas, Ummi; Pearce, Frazer R; Shattow, Genevieve M

    2012-01-01

    We analyze environmental correlations using mark clustering statistics with the mock galaxy catalogue constructed by Muldrew et al. (Paper I). We find that mark correlation functions are able to detect even a small dependence of galaxy properties on the environment, quantified by the overdensity $1+\\delta$, while such a small dependence would be difficult to detect by traditional methods. We then show that rank ordering the marks and using the rank as a weight is a simple way of comparing the correlation signals for different marks. With this we quantify to what extent fixed-aperture overdensities are sensitive to large-scale halo environments, nearest-neighbor overdensities are sensitive to small-scale environments within haloes, and colour is a better tracer of overdensity than is luminosity.

  16. A Pair of O VI and Broad Ly-alpha Absorbers Probing Warm Gas in a Galaxy Group Environment at z ~ 0.4

    CERN Document Server

    Pachat, Sachin; Muzahid, Sowgat; Khaire, Vikram; Srianand, Raghunathan; Wakker, Bart P; Savage, Blair D

    2016-01-01

    We report on the detection of two O VI absorbers separated in velocity by 710 km/s at z ~ 0.4 towards the background quasar SBS0957+599. Both absorbers are multiphase systems tracing substantial reservoirs of warm baryons. The low and intermediate ionization metals in the first absorber is consistent with an origin in photoionized gas. The O VI has a velocity structure different from other metal species. The Ly-alpha shows the presence of a broad feature. The line widths for O VI and the broad Ly-alpha suggest T = 7.1 x 10^5 K. This warm medium is probing a baryonic column which is an order of magnitude more than the total hydrogen in the cooler photoionized gas. The second absorber is detected only in H I and O VI. Here the temperature of 4.6 x 10^4 K supports O VI originating in a low-density photoionized gas. A broad component is seen in the Ly-alpha, offset from the O VI. The temperature in the broad Ly-alpha is T < 2.1 x 10^5 K. The absorbers reside in a galaxy overdensity region with 7 spectroscopica...

  17. EXTENDED [C II] EMISSION IN LOCAL LUMINOUS INFRARED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-Santos, T.; Armus, L.; Surace, J. A. [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States); Charmandaris, V. [Department of Physics, University of Crete, GR-71003 Heraklion (Greece); Stacey, G. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Murphy, E. J. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Haan, S. [CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Stierwalt, S.; Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Malhotra, S. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Appleton, P. [NASA Herschel Science Center, IPAC, California Institute of Technology, MS 100-22, Cech, Pasadena, CA 91125 (United States); Inami, H. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Magdis, G. E. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Elbaz, D. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu, CNRS, Universite Paris Diderot, Saclay, F-91191 Gif-sur-Yvette (France); Mazzarella, J. M.; Xu, C. K.; Lu, N.; Howell, J. H. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Van der Werf, P. P.; Meijerink, R., E-mail: tanio@ipac.caltech.edu [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); and others

    2014-06-10

    We present Herschel/PACS observations of extended [C II] 157.7 μm line emission detected on ∼1-10 kpc scales in 60 local luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey. We find that most of the extra-nuclear emission show [C II]/FIR ratios ≥4 × 10{sup –3}, larger than the mean ratio seen in the nuclei, and similar to those found in the extended disks of normal star-forming galaxies and the diffuse interstellar medium of our Galaxy. The [C II] ''deficits'' found in the most luminous local LIRGs are therefore restricted to their nuclei. There is a trend for LIRGs with warmer nuclei to show larger differences between their nuclear and extra-nuclear [C II]/FIR ratios. We find an anti-correlation between [C II]/FIR and the luminosity surface density, Σ{sub IR}, for the extended emission in the spatially resolved galaxies. However, there is an offset between this trend and that found for the LIRG nuclei. We use this offset to derive a beam filling-factor for the star-forming regions within the LIRG disks of ∼6% relative to their nuclei. We confront the observed trend to photo-dissociation region models and find that the slope of the correlation is much shallower than the model predictions. Finally, we compare the correlation found between [C II]/FIR and Σ{sub IR} with measurements of high-redshift starbursting IR-luminous galaxies.

  18. Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548

    DEFF Research Database (Denmark)

    Vestergaard, Marianne; Peterson, B. M.

    2005-01-01

    We study the low-contrast Fe II emission blends in the ultraviolet (1250--2200A) and optical (4000--6000A) spectra of the Seyfert 1 galaxy NGC 5548 and show that these features vary in flux and that these variations are correlated with those of the optical continuum. The amplitude of variability ...

  19. Warm absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies: I. A global view and frequency of occurrence of warm absorbers

    CERN Document Server

    Laha, Sibasish; Dewangan, Gulab C; Chakravorty, Susmita; Kembhavi, Ajit K

    2014-01-01

    We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. Our goal is to characterise the warm absorber (WA) properties along the line-of-sight to the active nucleus. We significantly detect WAs in $65\\%$ of the sample sources. Our results are consistent with WAs being present in at least half of the Seyfert galaxies in the nearby Universe, in agreement with previous estimates . We find a gap in the distribution of the ionisation parameter in the range $0.5<\\log\\xi<1.5$ which we interpret as a thermally unstable region for WA clouds. This may indicate that the warm absorber flow is probably constituted by a clumpy distribution of discrete clouds rather than a continuous medium. The distribution of the WA column densities for the sources with broad Fe K$\\alpha$ lines are similar to those sources which do not have broadened emission l...

  20. The SAMI Galaxy Survey: The discovery of a luminous, low-metallicity H II complex in the dwarf galaxy GAMA J141103.98-003242.3

    CERN Document Server

    Richards, S N; Lopez-Sanchez, A R; Croom, S M; Bryant, J J; Sweet, S M; Konstantopoulos, I S; Allen, J T; Bland-Hawthorn, J; Bloom, J V; Brough, S; Fogarty, L M R; Goodwin, M; Green, A W; Ho, I -T; Kewley, L J; Koribalski, B S; Lawrence, J S; Owers, M S; Sadler, E M; Sharp, R

    2014-01-01

    We present the discovery of a luminous unresolved H II complex on the edge of dwarf galaxy GAMA J141103.98-003242.3 using data from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. This dwarf galaxy is situated at a distance of ~100 Mpc and contains an unresolved region of H II emission that contributes ~70 per cent of the galaxy's H_alpha luminosity, located at the top end of established H II region luminosity functions. For the H II complex, we measure a star-formation rate of 0.147\\pm0.041 M_solar yr^-1 and a metallicity of 12+log(O/H) = 8.01\\pm0.05 that is lower than the rest of the galaxy by ~0.2 dex. Data from the H I Parkes All-Sky Survey (HIPASS) indicate the likely presence of neutral hydrogen in the galaxy to potentially fuel ongoing and future star-forming events. We discuss various triggering mechanisms for the intense star-formation activity of this H II complex, where the kinematics of the ionised gas are well described by a rotating disc and do not show any features...

  1. Dust origin in late-type dwarf galaxies: ISM growth vs. type II supernovae

    CERN Document Server

    Zhukovska, Svitlana

    2014-01-01

    We re-evaluate the roles of different dust sources in dust production as a function of metallicity in late-type dwarf galaxies, with the goal of understanding the relation between dust content and metallicity. The dust content ol late-type dwarf galaxies with episodic star formation is studied with a multicomponent model of dust evolution, which includes dust input from AGB stars, type II SNe and dust growth by accretion of atoms in the ISM. Dust growth in the ISM becomes an important dust source in dwarf galaxies, on the timescale of 0.1 - a few Gyrs. It increases the dust-to-gas ratio (DGR) during post-burst evolution, unlike type II SNe, which eject grains to the ISM only during starbursts. Before the dust growth in the ISM overtakes the dust production, AGB stars can be major sources of dust in metal-poor dwarf galaxies. Our models reproduce the relation between the DGR and oxygen abundance, derived from observations of a large sample of dwarf galaxies. The steep decrease in the DGR at low O values is exp...

  2. FLAIR-II spectroscopy of two DENIS J-band galaxy samples

    CERN Document Server

    Mamon, G A; Proust, D; Mamon, Gary A.; Parker, Quentin A.; Proust, Dominique

    2001-01-01

    As a pilot survey for the forthcoming 6dF Galaxy Redshift Survey, spectroscopy of galaxies selected in J (1.2 mu) with the DENIS survey was performed at the UKST using the FLAIR II multi-object spectroscope. 69 galaxy redshifts (z's) were obtained in a high |b| field and an additional 12 z's in a low latitude (b=-17 deg), obscured field. This study illustrates the feasibility of obtaining z's with optical spectra on galaxies selected at much longer wavelengths. It validated a very preliminary algorithm for star/galaxy separation for high |b| DENIS objects, with 99% reliability for J < 13.9. However, the FLAIR II z determinations required substantially longer integration times to achieve 90% completeness than expected from previous optical surveys at comparable depth. This is mainly due to a degradation in overall fibre throughput due to known problems with ageing of the prism-cement-fibre interface with exposure to UV light. Our low |b| (high extinction) field required 2.5 times more exposure time for less...

  3. The Effect of Host Galaxies on Type Ia Supernovae in the SDSS-II Supernova Survey

    CERN Document Server

    Lampeitl, Hubert; Nichol, Robert C; Bassett, Bruce; Cinabro, David; Dilday, Benjamin; Foley, Ryan J; Frieman, Joshua A; Garnavich, Peter M; Goobar, Ariel; Im, Myungshin; Jha, Saurabh W; Marriner, John; Miquel, Ramon; Nordin, Jakob; Östman, Linda; Riess, Adam G; Sako, Masao; Schneider, Donald P; Sollerman, Jesper; Stritzinger, Maximilian

    2010-01-01

    We present an analysis of the host galaxy dependencies of Type Ia Supernovae (SNe Ia) from the full three year sample of the SDSS-II Supernova Survey. We rediscover, to high significance, the strong correlation between host galaxy typeand the width of the observed SN light curve, i.e., fainter, quickly declining SNe Ia favor passive host galaxies, while brighter, slowly declining Ia's favor star-forming galaxies. We also find evidence (at between 2 to 3 sigma) that SNe Ia are ~0.1 magnitudes brighter in passive host galaxies, than in star-forming hosts, after the SN Ia light curves have been standardized using the light curve shape and color variations: This difference in brightness is present in both the SALT2 and MCLS2k2 light curve fitting methodologies. We see evidence for differences in the SN Ia color relationship between passive and star-forming host galaxies, e.g., for the MLCS2k2 technique, we see that SNe Ia in passive hosts favor a dust law of R_V ~1, while SNe Ia in star-forming hosts require R_V ...

  4. Dwarf Galaxies in the Coma Cluster: II. Spectroscopic and Photometric Fundamental Planes

    CERN Document Server

    Kourkchi, E; Carter, D; Mobasher, B

    2011-01-01

    We present a study of the fundamental plane, FP, for a sample of 71 dwarf galaxies in the core of Coma cluster in magnitude range $-21 < M_I <-15$. Taking advantage of high resolution DEIMOS spectrograph on Keck II for measuring the internal velocity dispersion of galaxies and high resolution imaging of HST/ACS, which allows an accurate surface brightness modeling, we extend the fundamental plane (FP) of galaxies to $\\sim$1 magnitude fainter luminosities than all the previous studies of the FP in Coma cluster. We find that, the scatter about the FP depends on the faint-end luminosity cutoff, such that the scatter increases for fainter galaxies. The residual from the FP correlates with the galaxy colour, with bluer galaxies showing larger residuals from FP. We find $M/L \\propto M^{-0.15\\pm0.22}$ in F814W-band indicating that in faint dwarf ellipticals, the $M/L$ ratio is insensitive to the mass. We find that less massive dwarf ellipticals are bluer than their brighter counterparts, possibly indicating on...

  5. CCD surface photometry of radio galaxies: Pt. 1. FR class I and II sources

    Energy Technology Data Exchange (ETDEWEB)

    Owen, F.N.; Laing, R.A.

    1989-05-01

    CCD surface photometry of 47 radio galaxies in the R-band is reported. The goal of the programme is to study the relationship of the properties of the parent galaxies to the radio structure and, in particular, to look for differences between Fanaroff and Riley (FR) class I and II sources. In order to clarify some ambiguous cases in the FR classification, we define Classical Double, Twin Jet and Fat Double sources. We describe our definitions of these three classes and their relation to the FR classification. (author).

  6. Search for [C II] emission in z = 6.5-11 star-forming galaxies

    Energy Technology Data Exchange (ETDEWEB)

    González-López, Jorge; Infante, Leopoldo [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago (Chile); Riechers, Dominik A., E-mail: jgonzal@astro.puc.cl, E-mail: linfante@astro.puc.cl [Astronomy Department, Cornell University 220 Space Sciences Building, Ithaca, NY 14853 (United States); and others

    2014-04-01

    We present the search for the [C II] emission line in three z > 6.5 Lyα emitters (LAEs) and one J-dropout galaxy using the Combined Array for Research in Millimeter-wave Astronomy and the Plateau de Bure Interferometer. We observed three bright z ∼ 6.5-7 LAEs discovered in the Subaru Deep Field (SDF) and the multiple imaged lensed z ∼ 11 galaxy candidate found behind the galaxy cluster MACSJ0647.7+7015. For the LAEs IOK-1 (z = 6.965), SDF J132415.7+273058 (z = 6.541), and SDF J132408.3+271543 (z = 6.554) we find upper limits for the [C II] line luminosity of <2.05, <4.52, and <10.56 × 10{sup 8} L {sub ☉}, respectively. We find upper limits to the far-IR (FIR) luminosity of the galaxies using a spectral energy distribution template of the local galaxy NGC 6946 and taking into account the effects of the cosmic microwave background on the millimeter observations. For IOK-1, SDF J132415.7+273058, and SDF J132408.3+271543 we find upper limits for the FIR luminosity of <2.33, 3.79, and 7.72 × 10{sup 11} L {sub ☉}, respectively. For the lensed galaxy MACS0647-JD, one of the highest-redshift galaxy candidates to date with z{sub ph}=10.7{sub −0.4}{sup +0.6}, we put an upper limit in the [C II] emission of <1.36 × 10{sup 8} × (μ/15){sup –1} L {sub ☉} and an upper limit in the FIR luminosity of <6.1 × 10{sup 10} × (μ/15){sup –1} L {sub ☉} (where μ is the magnification factor). We explore the different conditions relevant for the search for [C II] emission in high-redshift galaxies as well as the difficulties for future observations with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Cerro Chajnantor Atacama Telescope (CCAT).

  7. Ultraviolet absorbance titration for the determination of conditional stability constants of Hg(II) and dissolved organic matter

    Institute of Scientific and Technical Information of China (English)

    BAI Yingchen; WU Fengchang; WAN Guojiang; LIU Congqiang; FU Pingqing; LI Wen

    2008-01-01

    Strong interaction between natural dissolved organic matter (DOM) and Hg(II) may influence the transport, conversion, toxicity and bio-validity of mercury in the environment. In this paper ultraviolet (UV) absorbance titration was employed for the first time for the determination of the conditional stability constants of Hg(II) and (DOM). With increasing Hg(II) concentrations, the UV absorbance of fulvic acid, humic acid, and DOM in river increases progressively. By linear and non-linear model fitting, the conditional stability constants (lgK) of Hg(II) and DOM were worked out to be 3.54-4.93 and 3.64-4.85, respectively. The results are consistent with those acquired by the typical fluorescence quenching titration method, with the maximum relative error of lgK being 2.6% and the average relative error being 0.2%. The UV absorbance titration method has the advantages of rapid determination, simple performance, and it will probably become a new approach to studying interactions between DOM and trace metallic ions.

  8. Radiative transfer meets Bayesian statistics: where does a galaxy's [C II] emission come from?

    Science.gov (United States)

    Accurso, G.; Saintonge, A.; Bisbas, T. G.; Viti, S.

    2017-01-01

    The [C II] 158 μm emission line can arise in all phases of the interstellar medium (ISM), therefore being able to disentangle the different contributions is an important yet unresolved problem when undertaking galaxy-wide, integrated [C II] observations. We present a new multiphase 3D radiative transfer interface that couples STARBURST99, a stellar spectrophotometric code, with the photoionization and astrochemistry codes MOCASSIN and 3D-PDR. We model entire star-forming regions, including the ionized, atomic, and molecular phases of the ISM, and apply a Bayesian inference methodology to parametrize how the fraction of the [C II] emission originating from molecular regions, f_{[C II],mol}, varies as a function of typical integrated properties of galaxies in the local Universe. The main parameters responsible for the variations of f_{[C II],mol} are specific star formation rate (SSFR), gas phase metallicity, H II region electron number density (ne), and dust mass fraction. For example, f_{[C II],mol} can increase from 60 to 80 per cent when either ne increases from 101.5 to 102.5 cm-3, or SSFR decreases from 10-9.6 to 10-10.6 yr-1. Our model predicts for the Milky Way that f_{[C II],mol} = 75.8 ± 5.9 per cent, in agreement with the measured value of 75 per cent. When applying the new prescription to a complete sample of galaxies from the Herschel Reference Survey, we find that anywhere from 60 to 80 per cent of the total integrated [C II] emission arises from molecular regions.

  9. Intrinsic alignments of galaxies in the MassiveBlack-II simulation: analysis of two-point statistics

    CERN Document Server

    Tenneti, Ananth; Mandelbaum, Rachel; Di Matteo, Tiziana; Feng, Yu; Khandai, Nishikanta

    2014-01-01

    The intrinsic alignment of galaxies with the large-scale density field is an important astrophysical contaminant in upcoming weak lensing surveys whilst offering insights into galaxy formation and evolution. We present detailed measurements of the galaxy intrinsic alignments and associated ellipticity-direction (ED) and projected shape ($w_{g+}$) correlation functions for galaxies in the cosmological hydrodynamic MassiveBlack-II (MB-II) simulation. We carefully assess the effects on galaxy shapes, misalignments and two-point statistics of iterative weighted (by mass, luminosity, and color) definitions of the (reduced and unreduced) inertia tensor. We find that iterative procedures must be adopted for a reliable measurement of reduced tensor but that luminosity versus mass weighting has only negligible effects. Blue galaxies exhibit stronger misalignments and suppressed $w_{g+}$ amplitude. Both ED and $w_{g+}$ correlations increase in amplitude with subhalo mass (in the range of $10^{10} - 6.0\\times 10^{14}h^{...

  10. Spectroscopy of H II Regions in the Late-Type Spiral Galaxy NGC 6946

    CERN Document Server

    Gusev, Alexander S; Dodonov, Sergey N; 10.1134/S1990341313010045

    2013-01-01

    We present the results of spectroscopy of 39 H II regions in the spiral galaxy NGC 6946. The spectral observations were carried out at the 6-m BTA telescope of the SAO RAS with the SCORPIO focal reducer in the multi-slit mode with the dispersion of 2.1A/px and spectral resolution of 10A. The absorption estimates for 39 H II regions were obtained. Using the "strong line" method (NS-calibration) we determined the electron temperature, and the abundances of oxygen and nitrogen for 30 H II regions. The radial gradients of O/H and N/H were constructed.

  11. Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: II. Control of the H II Region Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Dopita, M A; Fischera, J; Sutherland, R S; Kewley, L J; Tuffs, R J; Popescu, C C; van Breugel, W; Groves, B A; Leitherer, C

    2006-03-01

    We examine from a theoretical viewpoint how the physical parameters of H II regions are controlled both in normal galaxies and in starburst environments. These parameters are the H II region luminosity function, the time-dependent size, the covering fraction of molecular clouds, the pressure in the ionized gas and the ionization parameter. The factors which control them are the initial mass function of the exciting stars, the cluster mass function, the metallicity and the mean pressure in the surrounding interstellar medium. We investigate the sensitivity of the H{alpha} luminosity to the IMF, and find that this can translate to about 30% variation in derived star formation rates. The molecular cloud dissipation timescale is estimated from a case study of M17 to be {approx} 1 Myr. Based upon H II luminosity function fitting for nearby galaxies, we propose that the cluster mass function has a log-normal form peaking at {approx} 185M{sub {circle_dot}}. This suggests that the cluster mass function is the continuation of the stellar IMF to higher mass. The pressure in the H II regions is controlled by the mechanical luminosity flux from the central cluster. Since this is closely related to the ionizing photon flux, we show that the ionization parameter is not a free variable, and that the diffuse ionized medium may be composed of many large, faint and old H II regions. Finally, we derive theoretical probability distributions for the ionization parameter as a function of metallicity and compare these to those derived for SDSS galaxies.

  12. Luminosity function of [OII] emission-line galaxies in the MassiveBlack-II simulation

    CERN Document Server

    Park, KwangHo; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M; Feng, Yu; Khandai, Nishikanta

    2015-01-01

    We examine the luminosity function (LF) of [OII] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at $0.06 \\le z \\le 3.0$ using the [OII] emission line luminosity L([OII]). We confirm that the specific star formation rate matches that in the GAMA survey. We show that the [OII] LF at z=1.0 from the MBII shows a good agreement with the LFs from several surveys below L([OII])=$10^{43.0}$ erg/s while the low redshifts ($z \\le 0.3$) show an excess in the prediction of bright [OII] galaxies, but still displaying a good match with observations below L([OII])=$10^{41.6}$ erg/s. Based on the validity in reproducing the properties of [OII] galaxies at low redshift ($z \\le 1$), we forecast the evolution of the [OII] LF at high redshift ($z \\le 3$), which can be tested by upcoming surveys such as the HETDEX and DESI. The slopes of the LFs at bright and faint ends range from -3...

  13. Intrinsic alignments of disc and elliptical galaxies in the MassiveBlack-II and Illustris simulations

    Science.gov (United States)

    Tenneti, Ananth; Mandelbaum, Rachel; Di Matteo, Tiziana

    2016-11-01

    We study the shapes and intrinsic alignments of discs and elliptical galaxies in the MassiveBlack-II (MBII) and Illustris cosmological hydrodynamic simulations, with volumes of (100 h-1 Mpc)3 and (75 h-1 Mpc)3, respectively. We find that simulated disc galaxies are more oblate in shape and more misaligned with the shape of their host dark matter subhalo when compared with ellipticals. The disc major axis is found to be oriented towards the location of nearby elliptical galaxies. We also find that the discs are thinner in MBII and misalignments with dark matter halo orientations are smaller in both discs and ellipticals when compared with Illustris. As a result, the intrinsic alignment correlation functions at fixed mass have a higher amplitude in MBII than in Illustris. Finally, at scales above ˜0.1 h-1 Mpc, the intrinsic alignment two-point correlation functions for disc galaxies in both simulations are consistent with a null detection, unlike those for ellipticals. Despite significant differences in the treatments of hydrodynamics and baryonic physics in the simulations, we find that the wδ + correlation function scales similarly with transverse separation. However, the less massive galaxies show different scale dependence in the ellipticity-direction correlation. This result indicates that, while hydrodynamic simulations are a promising tool to study intrinsic alignments, further study is needed to understand the impact of differences in the implementations of hydrodynamics and baryonic feedback.

  14. Fingerprinting Dark Energy II: weak lensing and galaxy clustering tests

    CERN Document Server

    Sapone, Domenico; Amendola, Luca

    2010-01-01

    The characterization of dark energy is a central task of cosmology. To go beyond a cosmological constant, we need to introduce at least an equation of state and a sound speed and consider observational tests that involve perturbations. If dark energy is not completely homogeneous on observable scales then the Poisson equation is modified and dark matter clustering is directly affected. One can then search for observational effects of dark energy clustering using dark matter as a probe. In this paper we exploit an analytical approximate solution of the perturbation equations in a general dark energy cosmology to analyze the performance of next-decade large scale surveys in constraining equation of state and sound speed. We find that tomographic weak lensing and galaxy redshift surveys can constrain the sound speed of the dark energy only if the latter is small, of the order of $c_{s}\\lesssim0.01$ (in units of $c$). For larger sound speeds the error grows to 100% and more. We conclude that large scale structure...

  15. nIFTy galaxy cluster simulations II: radiative models

    CERN Document Server

    Sembolini, Federico; Pearce, Frazer R; Power, Chris; Knebe, Alexander; Kay, Scott T; Cui, Weiguang; Yepes, Gustavo; Beck, Alexander M; Borgani, Stefano; Cunnama, Daniel; Davé, Romeel; February, Sean; Huang, Shuiyao; Katz, Neal; McCarthy, Ian G; Murante, Giuseppe; Newton, Richard D A; Perret, Valentin; Saro, Alexandro; Schaye, Joop; Teyssier, Romain

    2015-01-01

    We have simulated the formation of a massive galaxy cluster (M$_{200}^{\\rm crit}$ = 1.1$\\times$10$^{15}h^{-1}M_{\\odot}$) in a $\\Lambda$CDM universe using 10 different codes (RAMSES, 2 incarnations of AREPO and 7 of GADGET), modeling hydrodynamics with full radiative subgrid physics. These codes include Smoothed-Particle Hydrodynamics (SPH), spanning traditional and advanced SPH schemes, adaptive mesh and moving mesh codes. Our goal is to study the consistency between simulated clusters modeled with different radiative physical implementations - such as cooling, star formation and AGN feedback. We compare images of the cluster at $z=0$, global properties such as mass, and radial profiles of various dynamical and thermodynamical quantities. We find that, with respect to non-radiative simulations, dark matter is more centrally concentrated, the extent not simply depending on the presence/absence of AGN feedback. The scatter in global quantities is substantially higher than for non-radiative runs. Intriguingly, a...

  16. SALT spectroscopic observations of galaxy clusters detected by ACT and a Type II quasar hosted by a brightest cluster galaxy

    CERN Document Server

    Kirk, Brian; Cress, Catherine; Crawford, Steven M; Hughes, John P; Battaglia, Nicholas; Bond, J Richard; Burke, Claire; Gralla, Megan B; Hajian, Amir; Hasselfield, Matthew; Hincks, Adam D; Infante, Leopoldo; Kosowsky, Arthur; Marriage, Tobias A; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D; Sievers, Jonathan L; Sifón, Cristóbal; Wilson, Susan; Wollack, Edward J; Zunckel, Caroline

    2014-01-01

    We present Southern African Large Telescope (SALT) follow-up observations of seven massive clusters detected by the Atacama Cosmology Telescope (ACT) on the celestial equator using the Sunyaev-Zel'dovich (SZ) effect. We conducted multi-object spectroscopic observations with the Robert Stobie Spectrograph in order to measure galaxy redshifts in each cluster field, determine the cluster line-of-sight velocity dispersions, and infer the cluster dynamical masses. We find that the clusters, which span the redshift range 0.3 < z < 0.55, range in mass from (5 -- 20) x 10$^{14}$ solar masses (M200c). Their masses, given their SZ signals, are similar to those of southern hemisphere ACT clusters previously observed using Gemini and the VLT. We note that the brightest cluster galaxy in one of the systems studied, ACT-CL J0320.4+0032 at z = 0.38, hosts a Type II quasar. To our knowledge, this is only the third such system discovered, and therefore may be a rare example of a very massive halo in which quasar-mode fe...

  17. A Quadruple-Phase Strong Mg II Absorber at z~0.9902 Toward PG 1634+706

    CERN Document Server

    Ding, J; Bond, N A; Zonak, S G; Churchill, C W

    2003-01-01

    The z=0.9902 system along the quasar PG 1634+706 line of sight is a strong MgII absorber (W(2796)>0.3A) with only weak CIV absorption (it is ``CIV-deficient''). To study this system, we used high-resolution spectra from both HST/STIS (R=30,000) and Keck/HIRES (R=45,000). These spectra cover key transitions, such as MgI, MgII, FeII, SiII, CII, SiIII, CIII, SiIV, and CIV. Assuming a Haardt and Madau extragalactic background spectrum, we modeled the system with a combination of photoionization and collisional ionization. Based on a comparison of synthetic spectra to the data profiles, we infer the existence of the following four phases of gas: i) Seven MgII clouds have sizes of 1-1000pc and densities of 0.002-0.1/cm^3, with a gradual decrease in density from blue to red. The MgII phase gives rise to most of the CIV absorption and resembles the warm, ionized inter-cloud medium of the Milky Way; ii) Instead of arising in the same phase as MgII, MgI is produced in separate, narrow components with b~0.75km/s. These ...

  18. About the Emission Line Sequence of H II Galaxies

    Directory of Open Access Journals (Sweden)

    Grażyna Stasińska

    2003-01-01

    Full Text Available Se consideran 400 galaxias H II para las cuales se obtuvo la abundancia de oxígeno por métodos basados en la temperatura electrónica. Se divide la muestra en 3 conjuntos de diferente metalicidad. En cada conjunto se encuentra una secuencia angosta no solo en diagramas de cocientes de líneas de emisión sino también en términos del ancho equivalente de Hβ, lo que indica la existencia de una secuencia evolutiva. Nuestros diagramas muestran sin ambigüedad la existencia de evolución en una escala de tiempo de unos cuantos millones de años (Ma. Se comparan las secuencias observadas con modelos de fotoionización de la metalicidad apropiada. Para poder entender la evolución de galaxias H II uno debe considerar la evolución tanto del gas como de las estrellas. Las observaciones requieren que el EW(Hβ decrezca mas rápidamente que los valores predichos por la evolución pasiva de un brote de formación estelar. Una burbuja adiabática fotoionizada en expansión con un factor de cobertura decreciente en el tiempo reproduce la mayoría de los diagramas. Sin embargo, la cuestión del calentamiento de galaxias H II y el origen de la emisión nebular de He II λ4686 no se resuelven. Encontramos evidencia de autoenriquecimiento en nitrógeno en una escala de tiempo de varios Ma.

  19. THE INCLINATION OF THE DWARF IRREGULAR GALAXY HOLMBERG II

    Directory of Open Access Journals (Sweden)

    F. J. Sánchez-Salcedo

    2014-01-01

    Full Text Available Damos restricciones al ́angulo de inclinaci ́on del disco de H i de la galaxia irregular enana Holmberg II (Ho II a partir de un an ́alisis de la estabilidad gravita cional del disco de gas en las partes externas. Encontramos que se requiere un ́angulo de inclinaci ́on medio de 27 ◦ y, por lo tanto, una velocidad circular en su parte plana de ≈ 60 km s − 1 , para tener un grado de estabilidad similar al que tienen otras galaxias. Para esa inclinaci ́on, Ho II cae en la posici ́on correcta en la relaci ́on de Tully-Fisher bar i ́onica y, adem ́as, su curva de rotaci ́on es congruente con MOND. Sin embargo, el an ́alisi s de estabilidad correspondiente indica que esta galaxia podr ́ıa ser problem ́atica para MOND porque las partes externas de esta galaxia ser ́ıan marginalmente inest ables bajo esa teor ́ıa de gravedad. Se requieren simulaciones num ́ericas de las galaxias enanas ricas en gas para ver la factibilidad de MOND.

  20. nIFTy galaxy cluster simulations - II. Radiative models

    Science.gov (United States)

    Sembolini, Federico; Elahi, Pascal Jahan; Pearce, Frazer R.; Power, Chris; Knebe, Alexander; Kay, Scott T.; Cui, Weiguang; Yepes, Gustavo; Beck, Alexander M.; Borgani, Stefano; Cunnama, Daniel; Davé, Romeel; February, Sean; Huang, Shuiyao; Katz, Neal; McCarthy, Ian G.; Murante, Giuseppe; Newton, Richard D. A.; Perret, Valentin; Puchwein, Ewald; Saro, Alexandro; Schaye, Joop; Teyssier, Romain

    2016-07-01

    We have simulated the formation of a massive galaxy cluster (M_{200}^crit = 1.1 × 1015 h-1 M⊙) in a Λ cold dark matter universe using 10 different codes (RAMSES, 2 incarnations of AREPO and 7 of GADGET), modelling hydrodynamics with full radiative subgrid physics. These codes include smoothed-particle hydrodynamics (SPH), spanning traditional and advanced SPH schemes, adaptive mesh and moving mesh codes. Our goal is to study the consistency between simulated clusters modelled with different radiative physical implementations - such as cooling, star formation and thermal active galactic nucleus (AGN) feedback. We compare images of the cluster at z = 0, global properties such as mass, and radial profiles of various dynamical and thermodynamical quantities. We find that, with respect to non-radiative simulations, dark matter is more centrally concentrated, the extent not simply depending on the presence/absence of AGN feedback. The scatter in global quantities is substantially higher than for non-radiative runs. Intriguingly, adding radiative physics seems to have washed away the marked code-based differences present in the entropy profile seen for non-radiative simulations in Sembolini et al.: radiative physics + classic SPH can produce entropy cores, at least in the case of non cool-core clusters. Furthermore, the inclusion/absence of AGN feedback is not the dividing line -as in the case of describing the stellar content - for whether a code produces an unrealistic temperature inversion and a falling central entropy profile. However, AGN feedback does strongly affect the overall stellar distribution, limiting the effect of overcooling and reducing sensibly the stellar fraction.

  1. Cosmology and astrophysics from relaxed galaxy clusters - II. Cosmological constraints

    Science.gov (United States)

    Mantz, A. B.; Allen, S. W.; Morris, R. G.; Rapetti, D. A.; Applegate, D. E.; Kelly, P. L.; von der Linden, A.; Schmidt, R. W.

    2014-05-01

    This is the second in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. The data set employed here consists of Chandra observations of 40 such clusters, identified in a comprehensive search of the Chandra archive for hot (kT ≳ 5 keV), massive, morphologically relaxed systems, as well as high-quality weak gravitational lensing data for a subset of these clusters. Here we present cosmological constraints from measurements of the gas mass fraction, fgas, for this cluster sample. By incorporating a robust gravitational lensing calibration of the X-ray mass estimates, and restricting our measurements to the most self-similar and accurately measured regions of clusters, we significantly reduce systematic uncertainties compared to previous work. Our data for the first time constrain the intrinsic scatter in fgas, 7.4 ± 2.3 per cent in a spherical shell at radii 0.8-1.2 r2500 (˜1/4 of the virial radius), consistent with the expected level of variation in gas depletion and non-thermal pressure for relaxed clusters. From the lowest redshift data in our sample, five clusters at z 1, we obtain consistent results for Ωm and interesting constraints on dark energy: Ω _{{Λ }}=0.65^{+0.17}_{-0.22}> for non-flat ΛCDM (cosmological constant) models, and w = -0.98 ± 0.26 for flat models with a constant dark energy equation of state. Our results are both competitive and consistent with those from recent cosmic microwave background, Type Ia supernova and baryon acoustic oscillation data. We present constraints on more complex models of evolving dark energy from the combination of fgas data with these external data sets, and comment on the possibilities for improved fgas constraints using current and next-generation X-ray observatories and lensing data.

  2. Constraints on MACHO Dark Matter from the Star Cluster in the Dwarf Galaxy Eridanus II

    CERN Document Server

    Brandt, Timothy D

    2016-01-01

    I show that a recently discovered star cluster near the center of the ultra-faint dwarf galaxy Eridanus II provides strong constraints on massive compact halo objects (MACHOs) of >~5 M_sun as the main component of dark matter. MACHO dark matter will dynamically heat the cluster, driving it to larger sizes and higher velocity dispersions until it dissolves into its host galaxy. The star cluster has a luminosity of just ~2000 L_sun and is relatively puffy, with a half-light radius of 13 pc, making it much more fragile than other known clusters in dwarf galaxies. For a wide range of plausible dark matter halo properties, Eri II's star cluster combines with existing constraints from microlensing, wide binaries, and disk kinematics to rule out dark matter composed entirely of MACHOs from ~10$^{-7}$ M_sun up to arbitrarily high masses. The cluster in Eri II closes the ~20--100 M_sun window of allowed MACHO dark matter and provides much stronger constraints than wide Galactic binaries for MACHOs of up to thousands o...

  3. The Dark Matter Content of the Triangulum II Ultra-Faint Dwarf Galaxy

    Science.gov (United States)

    Kirby, Evan N.; Cohen, Judith G.; Simon, Joshua D.

    2017-01-01

    Triangulum II is an ultra-faint galaxy with a luminosity of 450 L⊙ discovered through Pan-STARRS imaging in 2015. Since then, two independent studies—including one of our own—based on Keck/DEIMOS spectroscopy found that the galaxy has a stellar velocity dispersion of about 5 km/s, indicating a very high concentration of dark matter. Here, we present additional DEIMOS observations over six epochs. We show that a combination of radial velocity variability (likely due to binarity) and inaccuracies in the previous measurements led to a spurious detection of a velocity dispersion in excess of what would be expected from the stellar population alone. Instead, we place an upper limits of 3.4 km/s (90% C.L.) and 4.3 km/s (95% C.L.) on the velocity dispersion. While these limits are compatible with very high mass-to-light ratios (1700 at 90% C.L. or 2600 at 95% C.L.), Triangulum II no longer seems extreme compared to dwarf galaxies of similar luminosity. Because the stars still span a large range of metallicity (-2.8 < [Fe/H] < -1.5), the galactic nature of Triangulum II is not in dispute.

  4. Complete element abundances of nine stars in the r-process galaxy Reticulum II

    CERN Document Server

    Ji, Alexander P; Simon, Joshua D; Chiti, Anirudh

    2016-01-01

    We present chemical abundances derived from high-resolution Magellan/MIKE spectra of the nine brightest known red giant members of the ultra-faint dwarf galaxy Reticulum II. These stars span the full metallicity range of Ret II (-3.5 < [Fe/H] < -2). Seven of the nine stars have extremely high levels of r-process material ([Eu/Fe]~1.7), in contrast to the extremely low neutron-capture element abundances found in every other ultra-faint dwarf galaxy studied to date. The other two stars are the most metal-poor stars in the system ([Fe/H] < -3), and they have neutron-capture element abundance limits similar to those in other ultra-faint dwarf galaxies. We confirm that the relative abundances of Sr, Y, and Zr in these stars are similar to those found in r-process halo stars but ~0.5 dex lower than the solar r-process pattern. If the universal r-process pattern extends to those elements, the stars in Ret II display the least contaminated known r-process pattern. The abundances of lighter elements up to the...

  5. On the newly discovered Canes Venatici II dSph galaxy

    CERN Document Server

    Greco, C; Clementini, G; Ripepi, V; Di Fabrizio, L; Kinemuchi, K; Marconi, M; Musella, I; Smith, H A; Rodgers, C T; Kuehn, C; Beers, T C; Catelan, M; Pritzl, B J

    2007-01-01

    We report on the detection of variable stars in the Canes Venatici II (CVn II) dwarf spheroidal galaxy, a new satellite of the Milky Way recently discovered by the Sloan Digital Sky Survey. We also present a V, B-V color-magnitude diagram that reaches V = 25.5 mag, showing the galaxy's main sequence turn off at V = 24.5 mag and revealing several candidate blue straggler stars. Two RR Lyrae stars have been identified within the half-light radius of CVn II,a fundamental-mode variable (RRab) with period P_ab = 0.743 days, and a first-overtone (RRc) RR Lyrae star with P_c = 0.358 days. The rather long periods of these variables along with their position on the period-amplitude diagram support an Oosterhoff type II classification for CVn II. The average apparent magnitude of the RR Lyrae stars, = 21.48 +/- 0.02 mag, is used to obtain a precision distance modulus of mu_0 = 21.02 +/- 0.06 mag and a corresponding distance of 160(+4,-5} kpc, for an adopted reddening E(B-V) = 0.015 mag.

  6. The Redshift Distribution of Intervening Weak MgII Quasar Absorbers and a Curious Dependence on Quasar Luminosity

    CERN Document Server

    Evans, Jessica L; Murphy, Michael T; Nielsen, Nikole M; Klimek, Elizabeth S

    2013-01-01

    We have identified 469 MgII doublet systems having W_r >= 0.02 {\\AA} in 252 Keck/HIRES and UVES/VLT quasar spectra over the redshift range 0.1 = 1.0 {\\AA}) absorbers. For weak absorption, dN/dz toward bright quasars is ~ 25% higher than toward faint quasars (10 sigma at low redshift, 0.4 <= z <= 1.4, and 4 sigma at high redshift, 1.4 < z <= 2.34). For strong absorption the trend reverses, with dN/dz toward faint quasars being ~ 20% higher than toward bright quasars (also 10 sigma at low redshift and 4 sigma at high redshift). We explore scenarios in which beam size is proportional to quasar luminosity and varies with absorber and quasar redshifts. These do not explain dN/dz's dependence on quasar luminosity.

  7. High resolution spectroscopy of H II Galaxies Structure and Supersonic line widths

    CERN Document Server

    Telles, E; Tenorio-Tagle, G; Telles, Eduardo; Munoz-Tunon, Casiana; Tenorio-Tagle, Guillermo

    2001-01-01

    We present high resolution echelle spectroscopy of a sample of H II galaxies. In all galaxies we identify different H(alpha) emitting knots along the slit crossing the nucleus. All of these have been isolated and separately analyzed through luminosity and size vs diagnosis plots. We find that in all cases, for a particular galaxy, the bulk of emission comes from their main knot and therefore, at least for the compact class galaxies we are dealing with, luminosity and sigma values measured using single aperture observations would provide similar results to what is obtained with spatially resolved spectroscopy. In the size vs plots as expected there is a shift in the correlations depending on whether we are including all emission in a single point or we split it in its different emitting knots. The problem of a proper determination of the size of the emitting region so that it can be used to determine the mass of the system remains open. From the data set gathered, using the highest surface brightness points as...

  8. H ii REGIONS WITHIN A COMPACT HIGH VELOCITY CLOUD. A NEARLY STARLESS DWARF GALAXY?

    Energy Technology Data Exchange (ETDEWEB)

    Bellazzini, M. [INAF—Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Magrini, L. [INAF—Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Mucciarelli, A.; Fraternali, F. [Dipartimento di Fisica and Astronomia, Università degli Studi di Bologna, Viale Berti Pichat, 6/2, I-40127 Bologna (Italy); Beccari, G. [European Southern Observatory, Alonso de Cordova 3107, Vitacura Santiago (Chile); Ibata, R.; Martin, N. [Obs. astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l’Université, F-67000 Strasbourg (France); Battaglia, G. [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Testa, V. [INAF—Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio (Italy); Fumana, M.; Marchetti, A. [INAF—IASF, via E. Bassini 15, I-20133, Milano (Italy); Correnti, M., E-mail: michele.bellazzini@oabo.inaf.it [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2015-02-10

    Within the SECCO survey we identified a candidate stellar counterpart to the Ultra Compact High Velocity Cloud (UCHVC) HVC274.68+74.70-123 that was suggested by Adams et al. to be a possible mini halo within the Local Group of galaxies. The spectroscopic follow-up of the brightest sources within the candidate reveals the presence of two H ii regions whose radial velocity is compatible with a physical association with the UVHVC. The available data do not allow us to give a definite answer on the nature of the newly identified system. A few alternative hypotheses are discussed. However, the most likely possibility is that we have found a new faint dwarf galaxy residing in the Virgo cluster of galaxies, which we name SECCO 1. Independently of its actual distance, SECCO 1 displays a ratio of neutral hydrogen mass to V luminosity of M{sub H} {sub I}/L{sub V}≳20, by far the largest among local dwarfs. Hence, it appears to be a nearly starless galaxy and it may be an example of the missing links between normal dwarfs and the dark mini halos that are predicted to exist in large numbers according to the currently accepted cosmological model.

  9. Structure and activity relationships for amine-based CO2 absorbents-II

    NARCIS (Netherlands)

    Niederer, J. P. M.; Versteeg, G. F.

    2009-01-01

    A study to determine the structure and activity relationships of various amine-based CO2 absorbents was performed, in which the absorption of pure CO2 at atmospheric pressure was measured to assess the total absorption rates and capacities. Steric hindrance effect was noticed when side chain with al

  10. Galaxy Clusters in the Line of Sight to Background Quasars: II. Environmental effects on the sizes of baryonic halo sizes

    CERN Document Server

    Padilla, N; López, S; Barrientos, L F; Lira, P; Andrews, H; Tejos, N

    2009-01-01

    Based on recent results on the frequency of MgII absorption line systems in the "QSO behind RCS clusters" survey (QbC), we analyse the effects of the cluster environment on the sizes of baryonic haloes around galaxies. We use two independent models, i) an empirical halo occupation model which fits current measurements of the clustering and luminosity function of galaxies at low and high redshifts, and ii) the GALFORM semi-analytic model of galaxy formation, which follows the evolution of the galaxy population from first principles, adjusted to match the statistics of low and high redshift galaxies. In both models we constrain the MgII halo sizes of field and cluster galaxies using observational results on the observed MgII statistics. Our results for the field are in good agreement with previous works, indicating a typical \\mgii\\ halo size of $r_MgII ~ 50h_71^-1kpc in the semi-analytic model, and slightly lower in the halo occupation number approach. For the cluster environment, we find that both models requi...

  11. X-ray emission from the nuclei, lobes and hot-gas environments of two FR-II radio galaxies

    CERN Document Server

    Croston, J H; Hardcastle, M J; Worrall, D M

    2004-01-01

    We report the detection of multiple components of X-ray emission from the two FR-II radio galaxies 3C 223 and 3C 284, based on new XMM-Newton observations. We attribute the detected X-ray emission from the lobes of both sources to inverse-Compton scattering of cosmic microwave background photons. With this model, we find that the magnetic field strength in the lobes is at the equipartition value for 3C 284, and within a factor of two of the equipartition value for 3C 223. We also detect group-scale hot atmospheres around both sources, and determine temperatures and pressures in the gas. The lobes of both sources are in pressure balance with the hot-gas environments, if the lobes contain only the synchrotron-emitting particles and the measured magnetic field strength. The core spectra of both sources contain an unabsorbed soft component, likely to be related to the radio jet, and an additional heavily absorbed power-law component. 3C 223 also displays a bright (EW ~ 500 eV) Fe K-alpha emission line.

  12. Directly imaging damped Ly-alpha galaxies at z>2. II: Imaging and spectroscopic observations of 32 quasar fields

    CERN Document Server

    Fumagalli, Michele; Prochaska, J Xavier; Kanekar, Nissim; Wolfe, Arthur M

    2014-01-01

    Damped Ly-alpha absorbers (DLAs) are a well-studied class of absorption line systems, and yet the properties of their host galaxies remain largely unknown. To investigate the origin of these systems, we have conducted an imaging survey of 32 quasar fields with intervening DLAs between z~1.9-3.8, leveraging a technique that allows us to image galaxies at any small angular separation from the background quasars. In this paper, we present the properties of the targeted DLA sample, new imaging observations of the quasar fields, and the analysis of new and archival spectra of the background quasars. In a companion paper we use these data to obtain an unbiased census of the DLA host galaxy population(s) and to directly measure the in-situ star formation rates of gas-rich galaxies at z>2.

  13. On The gamma-ray emission from Reticulum II and other dwarf galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Hooper, Dan; Linden, Tim

    2015-09-01

    The recent discovery of ten new dwarf galaxy candidates by the Dark Energy Survey (DES) and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) could increase the Fermi Gamma-Ray Space Telescope's sensitivity to annihilating dark matter particles, potentially enabling a definitive test of the dark matter interpretation of the long-standing Galactic Center gamma-ray excess. In this paper, we compare the previous analyses of Fermi data from the directions of the new dwarf candidates (including the relatively nearby Reticulum II) and perform our own analysis, with the goal of establishing the statistical significance of any gamma-ray signal from these sources. We confirm the presence of an excess from Reticulum II, with a spectral shape that is compatible with the Galactic Center signal. The significance of this emission is greater than that observed from 99.84% of randomly chosen high-latitude blank-sky locations, corresponding to a local detection significance of 3.2σ. We caution that any dark matter interpretation of this excess must be validated through observations of additional dwarf spheroidal galaxies, and improved calculations of the relative J-factor of dwarf spheroidal galaxies. We improve upon the standard blank-sky calibration approach through the use of multi-wavelength catalogs, which allow us to avoid regions that are likely to contain unresolved gamma-ray sources.

  14. Lyman Alpha and MgII as Probes of Galaxies and their Environments

    CERN Document Server

    Barnes, Luke A; Kacprzak, Glenn G

    2014-01-01

    Ly{\\alpha} emission, Ly{\\alpha} absorption and MgII absorption are powerful tracers of neutral hydrogen. Hydrogen is the most abundant element in the universe and plays a central role in galaxy formation via gas accretion and outflows, as well as being the precursor to molecular clouds, the sites of star formation. Since 21cm emission from neutral hydrogen can only be directly observed in the local universe, we rely on Ly{\\alpha} emission, and Ly{\\alpha} and MgII absorption to probe the physics that drives galaxy evolution at higher redshifts. Furthermore, these tracers are sensitive to a range of hydrogen densities that cover the interstellar medium, the circumgalactic medium and the intergalactic medium, providing an invaluable means of studying gas physics in regimes where it is poorly understood. At high redshift, Ly{\\alpha} emission line searches have discovered thousands of star-forming galaxies out to z = 7. The large Ly{\\alpha} scattering cross-section makes observations of this line sensitive to even...

  15. Molecular Hydrogen and [Fe II] in Active Galactic Nuclei III: LINERS and Star Forming Galaxies

    CERN Document Server

    Riffel, R; Aleman, I; Brotherton, M S; Pastoriza, M G; Bonatto, C J; Dors, O L

    2013-01-01

    We study the kinematics and excitation mechanisms of H2 and [Fe II] lines in a sample of 67 emission-line galaxies with Infrared Telescope Facility SpeX near-infrared (NIR, 0.8-2.4 micrometers) spectroscopy together with new photoionisation models. H2 emission lines are systematically narrower than narrow-line region (NLR) lines, suggesting that the two are, very likely, kinematically disconnected. The new models and emission-line ratios show that the thermal excitation plays an important role not only in active galactic nuclei but also in star forming galaxies. The importance of the thermal excitation in star forming galaxies may be associated with the presence of supernova remnants close to the region emitting H2 lines. This hypothesis is further supported by the similarity between the vibrational and rotational temperatures of H2. We confirm that the diagram involving the line ratios H2 2.121/Br_gamma and [Fe II] 1.257/Pa_beta is an efficient tool for separating emission-line objects according to their dom...

  16. Variable stars in the field of the Hydra II ultra-faint dwarf galaxy

    CERN Document Server

    Vivas, A Katherina; Olsen, Knut; Blum, Robert; Walker, Alistair; Martin, Nicolas; Besla, Gurtina; Gallart, Carme; van der Marel, Roeland; Majewski, Steven; Kaleida, Catherine; Muñoz, Ricardo; Conn, Blair; Jin, Shoko

    2015-01-01

    We report the discovery of one RR Lyrae star in the ultra--faint satellite galaxy Hydra II based on time series photometry in the g, r and i bands obtained with the Dark Energy Camera at Cerro Tololo Interamerican Observatory, Chile. The RR Lyrae star has a mean magnitude of $i = 21.30\\pm 0.04$ which translates to a heliocentric distance of $151\\pm 8$ kpc for Hydra II; this value is $\\sim 13\\%$ larger than the estimate from the discovery paper based on the average magnitude of several blue horizontal branch star candidates. The new distance implies a slightly larger half-light radius of $76^{+12}_{-10}$ pc and a brighter absolute magnitude of $M_V = -5.1 \\pm 0.3$, which keeps this object within the realm of the dwarf galaxies. The pulsational properties of the RR Lyrae star ($P=0.645$ d, $\\Delta g = 0.68$ mag) suggest Hydra II may be a member of the intermediate Oosterhoff or Oosterhoff II group. A comparison with other RR Lyrae stars in ultra--faint systems indicates similar pulsational properties among them...

  17. FR II radio galaxies at low frequencies I: morphology, magnetic field strength and energetics

    CERN Document Server

    Harwood, Jeremy J; Intema, Huib T; Stewart, Adam J; Ineson, Judith; Hardcastle, Martin J; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W

    2016-01-01

    Due to their steep spectra, low-frequency observations of FR II radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths has meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C452 and 3C223. We find that the morphology of 3C452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total ...

  18. Semiclassical and quantum theory of the bistability in lasers containing saturable absorbers. II

    Energy Technology Data Exchange (ETDEWEB)

    Dembinski, S.T.; Kossakowski, A.; Lugiato, L.A.; Mandel, P.

    1978-09-01

    We consider the time-evolution equation for the Glauber distribution function of the field emitted by a laser with saturable absorber and investigate the role of the terms with derivatives of order higher than second. It is found that the main effect of these terms is the following: When the relative saturability of the passive atoms with respect to the active atoms is very high, the (first-order-like) transition is much sharper than predicted by the Fokker-Planck equation.

  19. The Building the Bridge survey for z=3 Ly-alpha emitting galaxies II: Completion of the survey

    CERN Document Server

    Grove, L F; Ledoux, C; Limousin, M; Møller, P; Nilsson, K; Thomsen, B

    2009-01-01

    (Abridged). We aim at bridging the gap between absorption selected and emission selected galaxies at z~3 by probing the faint end of the luminosity function of star-forming galaxies at z~3. We have performed narrow-band imaging in three fields with intervening QSO absorbers (a damped Ly$\\alpha$ absorber and two Lyman-limit systems) using the VLT. We target Ly-alpha at redshifts 2.85, 3.15 and 3.20. We find a consistent surface density of about 10 Ly-alpha-emitters per square arcmin per unit redshift in all three fields down to our detection limit of about 3x10^41 ergs s^-1. The luminosity function is consistent with what has been found by other surveys at similar redshifts. About 85% of the sources are fainter than the canonical limit of R=25.5 for most Lyman-break galaxy surveys. In none of the three fields do we detect the emission counterparts of the QSO absorbers. In particular we do not detect the counterpart of the z=2.85 damped Ly-alpha absorber towards Q2138-4427. Narrow-band surveys for Ly-alpha emit...

  20. Dark matter annihilation and decay profiles for the Reticulum II dwarf spheroidal galaxy

    CERN Document Server

    Bonnivard, V; Maurin, D; Geringer-Sameth, A; Koushiappas, S M; Walker, M G; Mateo, M; Olszewski, E; Bailey, J I

    2015-01-01

    The dwarf spheroidal galaxies (dSph) of the Milky Way are among the most attractive targets for indirect searches of dark matter. In this work, we reconstruct the dark matter annihilation (J-factor) and decay profiles for the newly discovered dSph Reticulum~II. This is done using an optimized spherical Jeans analysis of kinematic data obtained from the Michigan/Magellan Fiber System (M2FS). We find Reticulum~II to have one of the highest J-factor when compared to the other Milky Way dSphs. We have also checked the robustness of this result against several ingredients of the analysis. Unless it suffers from tidal disruption or significant inflation of its velocity dispersion from binary stars, Reticulum~II may provide a unique window on dark matter particle properties.

  1. Suzaku view of X-ray Spectral Variability of the Radio Galaxy Centaurus A : Partial Covering Absorber, Reflector, and Possible Jet Component

    CERN Document Server

    Fukazawa, Y; Yamazaki, S; Mizuno, M; Hayashi, K; Hayashi, K; Nishino, S; Takahashi, H; Ohno, M

    2011-01-01

    We observed a nearby radio galaxy, the Centaurus A (Cen A), three times with Suzaku in 2009, and measured the wide-band X-ray spectral variability more accurately than the previous measurements. The Cen A was in the active phase in 2009, and the flux became higher by a factor of 1.5--2.0 and the spectrum became harder than that in 2005. The Fe-K line intensity increased by 20--30% from 2005 to 2009. The correlation of the count rate between the XIS 3--8 keV and PIN 15--40 keV band showed a complex behavior with a deviation from a linear relation. The wide-band X-ray continuum in 2--200 keV can be fitted with an absorbed powerlaw model plus a reflection component, or a powerlaw with a partial covering Compton-thick absorption. The difference spectra between high and low flux periods in each observation were reproduced by a powerlaw with a partial covering Compton-thick absorption. Such a Compton-thick partial covering absorber was for the first time observed for the Cen A. The powerlaw photon index of the diff...

  2. Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies

    Science.gov (United States)

    Laha, S.; Guainazzi, M.; Dewangan, G.; Chakravorty, S.; Kembhavi, A.

    2014-07-01

    We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. We could put a strict lower limit on the detection fraction of 50%. We find a gap in the distribution of the ionisation parameter in the range 0.5UFOs) do not represent extreme manifestation of the same astrophysical system.

  3. Surface Brightness Profiles of Dwarf Galaxies. II. Color Trends and Mass Profiles

    Science.gov (United States)

    Herrmann, Kimberly A.; Hunter, Deidre A.; Elmegreen, Bruce G.

    2016-06-01

    In this second paper of a series, we explore the B - V, U - B, and FUV-NUV radial color trends from a multi-wavelength sample of 141 dwarf disk galaxies. Like spirals, dwarf galaxies have three types of radial surface brightness profiles: (I) single exponential throughout the observed extent (the minority), (II) down-bending (the majority), and (III) up-bending. We find that the colors of (1) Type I dwarfs generally become redder with increasing radius, unlike spirals which have a blueing trend that flattens beyond ˜1.5 disk scale lengths, (2) Type II dwarfs come in six different “flavors,” one of which mimics the “U” shape of spirals, and (3) Type III dwarfs have a stretched “S” shape where the central colors are flattish, become steeply redder toward the surface brightness break, then remain roughly constant beyond, which is similar to spiral Type III color profiles, but without the central outward bluing. Faint (-9 > MB > -14) Type II dwarfs tend to have continuously red or “U” shaped colors and steeper color slopes than bright (-14 > MB > -19) Type II dwarfs, which additionally have colors that become bluer or remain constant with increasing radius. Sm dwarfs and BCDs tend to have at least some blue and red radial color trend, respectively. Additionally, we determine stellar surface mass density (Σ) profiles and use them to show that the break in Σ generally remains in Type II dwarfs (unlike Type II spirals) but generally disappears in Type III dwarfs (unlike Type III spirals). Moreover, the break in Σ is strong, intermediate, and weak in faint dwarfs, bright dwarfs, and spirals, respectively, indicating that Σ may straighten with increasing galaxy mass. Finally, the average stellar surface mass density at the surface brightness break is roughly 1-2 M⊙ pc-2 for Type II dwarfs but higher at 5.9 M⊙ pc-2 or 27 M⊙ pc-2 for Type III BCDs and dIms, respectively.

  4. ROSAT X-ray observations of the dwarf galaxy Holmberg II

    CERN Document Server

    Kerp, J; Brinks, E; Kerp, Juergen; Walter, Fabian; Brinks, Elias

    2002-01-01

    We present a study of the irregular dwarf galaxy Holmberg II based on ROSAT PSPC observations (total exposure time: 22 ksec). Holmberg II is a nearby (3.2 Mpc), well-studied dwarf irregular galaxy. It is famous for its interstellar medium which is dominated by expanding structures such as HI holes and shells. We search for X-ray emission from point sources as well as for diffuse emission, down to the detection limit of the ROSAT data. Using X-ray hardness ratio diagrams we differentiate between thermal plasma and power-law X-ray spectra which helps to determine the nature of the individual sources. Correlating the X-ray data with complementary observations ranging from the far-ultraviolet to the radio regime we increase the probability of correctly identifying sources belonging to Holmberg II. We did not detect soft X-ray emission originating from hot gas within supergiant HI shells above our luminosity sensitivity limit of (L_limit(0.1 - 2.1 keV) ~ 10^{37}erg/s). This finding can probably be attributed to bl...

  5. Surface Brightness Profiles of Dwarf Galaxies: II. Color Trends and Mass Profiles

    CERN Document Server

    Herrmann, Kimberly A; Elmegreen, Bruce G

    2016-01-01

    In this second paper of a series, we explore the B-V, U-B, and FUV-NUV radial color trends from a multi-wavelength sample of 141 dwarf disk galaxies. Like spirals, dwarf galaxies have three types of radial surface brightness profiles: (I) single exponential throughout the observed extent (the minority), (II) down-bending (the majority), and (III) up-bending. We find that colors of (1) Type I dwarfs generally become redder with increasing radius unlike spirals that have a blueing trend that flattens beyond ~1.5 disk scale lengths, (2) Type II dwarfs come in six different "flavors," one of which mimics the "U" shape of spirals, and (3) Type III dwarfs have a stretched "S" shape where central colors are flattish, become steeply redder to the surface brightness break, then remain roughly constant beyond, similar to spiral TypeIII color profiles, but without the central outward bluing. Faint (-9 > M_B > -14) Type II dwarfs tend to have continuously red or "U" shaped colors and steeper color slopes than bright (-14...

  6. Imprints of galaxy evolution on H ii regions Memory of the past uncovered by the CALIFA survey

    CERN Document Server

    Sanchez, S F; Rosales-Ortega, F F; Miralles-Caballero, D; Lopez-Sanchez, A R; Iglesias-Páramo, J; Marino, R A; Sánchez-Menguiano, L; García-Benito, R; Mast, D; Mendoza, M A; Papaderos, P; Ellis, S; Galbany, L; Kehrig, C; Monreal-Ibero, A; Delgado, R González; Mollá, M; Ziegler, B; de Lorenzo-Cáceres, A; Mendez-Abreu, J; Bland-Hawthorn, J; Bekeraite, S; Roth, M M; Pasquali, A; Díaz, A; Bomans, D; van de Ven, G; Wisotzki, L

    2014-01-01

    H ii regions in galaxies are the sites of star formation and thus particular places to understand the build-up of stellar mass in the universe. The line ratios of this ionized gas are frequently used to characterize the ionization conditions. We use the Hii regions catalogue from the CALIFA survey (~5000 H ii regions), to explore their distribution across the classical [OIII]/Hbeta vs. [NII]/Halpha diagnostic diagram, and how it depends on the oxygen abundance, ionization parameter, electron density, and dust attenuation. We compared the line ratios with predictions from photoionization models. Finally, we explore the dependences on the properties of the host galaxies, the location within those galaxies and the properties of the underlying stellar population. We found that the location within the BPT diagrams is not totally predicted by photoionization models. Indeed, it depends on the properties of the host galaxies, their galactocentric distances and the properties of the underlying stellar population. Thes...

  7. Stellar Kinematics and Metallicities in the Ultra-Faint Dwarf Galaxy Reticulum II

    CERN Document Server

    Simon, J D; Li, T S; Nord, B; Geha, M; Bechtol, K; Balbinot, E; Buckley-Geer, E; Lin, H; Marshall, J; Santiago, B; Strigari, L; Wang, M; Wechsler, R H; Yanny, B; Abbott, T; Bauer, A H; Bernstein, G M; Bertin, E; Brooks, D; Burke, D L; Capozzi, D; Rosell, A Carnero; Kind, M Carrasco; D'Andrea, C B; da Costa, L N; DePoy, D L; Desai, S; Diehl, H T; Dodelson, S; Cunha, C E; Estrada, J; Evrard, A E; Neto, A Fausti; Fernandez, E; Finley, D A; Flaugher, B; Frieman, J; Gaztanaga, E; Gerdes, D; Gruen, D; Gruendl, R A; Honscheid, K; James, D; Kuehn, K; Kuropatkin, N; Lahav, O; Maia, M A G; March, M; Martini, P; Miller, C J; Miquel, R; Ogando, R; Romer, A K; Roodman, A; Rykoff, E S; Sako, M; Sanchez, E; Schubnell, M; Sevilla, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Tucker, D; Vikram, V; Walker, A R; Wester, W

    2015-01-01

    We present Magellan/M2FS, VLT/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity of 62.8 +/- 0.5 km/s and a velocity dispersion of 3.3 +/- 0.7 km/s. The mass-to-light ratio of Ret II within its half-light radius is 470 +/- 210 Msun/Lsun, demonstrating that it is a strongly dark matter-dominated system. Despite its spatial proximity to the Magellanic Clouds, the radial velocity of Ret II differs from that of the LMC and SMC by 199 and 83 km/s, respectively, suggesting that it is not gravitationally bound to the Magellanic system. The likely member stars of Ret II span 1.3 dex in metallicity, with a dispersion of 0.28 +/- 0.09 dex, and we identify several extremely metal-poor stars with [Fe/H] < -3. In combination with its luminosity, size, and ellipticity, these results confirm that Ret II is an ultra-faint dwarf galaxy. With a me...

  8. 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,...

  9. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics

    Science.gov (United States)

    Harwood, Jeremy J.; Croston, Judith H.; Intema, Huib T.; Stewart, Adam J.; Ineson, Judith; Hardcastle, Martin J.; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K.; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W.

    2016-06-01

    Due to their steep spectra, low-frequency observations of Fanaroff-Riley type II (FR II) radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths have meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR (LOw Frequency ARray) observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C 452 and 3C 223. We find that the morphology of 3C 452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total energy content of the lobes is greater than previous estimates by a factor of around 5 for 3C 452 and 2 for 3C 223. We go on to discuss possible causes of these steeper-than-expected spectra and provide revised estimates of the internal pressures and magnetic field strengths for the intrinsically steep case. We find that the ratio between the equipartition magnetic field strengths and those derived through synchrotron/inverse-Compton model fitting remains consistent with previous findings and show that the observed departure from equipartition may in some cases provide a solution to the spectral versus dynamical age disparity.

  10. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics.

    Science.gov (United States)

    Harwood, Jeremy J; Croston, Judith H; Intema, Huib T; Stewart, Adam J; Ineson, Judith; Hardcastle, Martin J; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W

    2016-06-01

    Due to their steep spectra, low-frequency observations of Fanaroff-Riley type II (FR II) radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths have meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR (LOw Frequency ARray) observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C 452 and 3C 223. We find that the morphology of 3C 452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total energy content of the lobes is greater than previous estimates by a factor of around 5 for 3C 452 and 2 for 3C 223. We go on to discuss possible causes of these steeper-than-expected spectra and provide revised estimates of the internal pressures and magnetic field strengths for the intrinsically steep case. We find that the ratio between the equipartition magnetic field strengths and those derived through synchrotron/inverse-Compton model fitting remains consistent with previous findings and show that the observed departure from equipartition may in some cases provide a solution to the spectral versus dynamical age disparity.

  11. Collisional excitation of [C II], [O I] and CO in Massive Galaxies

    CERN Document Server

    Canning, R E A; Fabian, A C; Johnstone, R M; van Hoof, P A M; Porter, R L; Werner, N; Williams, R J R

    2015-01-01

    Many massive galaxies at the centres of relaxed galaxy clusters and groups have vast reservoirs of cool (~10,000 K) and cold (~100 K) gas. In many low redshift brightest group and cluster galaxies this gas is lifted into the hot ISM in filamentary structures, which are long lived and are typically not forming stars. Two important questions are how far do these reservoirs cool and if cold gas is abundant what is the cause of the low star formation efficiency? Heating and excitation of the filaments from collisions and mixing of hot particles in the surrounding X-ray gas describes well the optical and near infra-red line ratios observed in the filaments. In this paper we examine the theoretical properties of dense, cold clouds emitting in the far infra-red and submillimeter through the bright lines of [C II]157 \\mu m , [O I]63 \\mu m and CO, exposed to these energetic ionising particles. While some emission lines may be optically thick we find this is not sufficient to model the emission line ratios. Models wher...

  12. The MassiveBlack-II Simulation: The Evolution of Halos and Galaxies to z~0

    CERN Document Server

    Khandai, Nishikanta; Croft, Rupert; Wilkins, Stephen M; Feng, Yu; Tucker, Evan; DeGraf, Colin; Liu, Mao-Sheng

    2014-01-01

    (Abridged for arXiv)We investigate the properties of halos, galaxies and blackholes to z=0 in the high resolution hydrodynamical simulation MassiveBlack-II (MBII) which evolves a LCDM cosmology in a comoving volume Vbox=100(Mpc/h)^3. MBII is the highest resolution simulation of this size which includes a self-consistent model for star formation, black hole accretion and associated feedback. We provide a simulation browser web application which enables interactive search and tagging of halos, subhalos and their properties and publicly release our galaxy catalogs. Our analysis of the halo mass function (MF) in MBII reveals that baryons have strong effects, with changes in the halo abundance of 20-35% below the knee of the MF (Mhalo =2. At z10^11 Msun) galaxies hosting bright AGNs make significant contributions to the GSMF. The quasar bolometric luminosity function is also largely consistent with observations. We note however that more efficient AGN feedback (beyond simple thermal coupling used here) is likely n...

  13. Satellite abundances around bright isolated galaxies II: radial distribution and environmental effects

    CERN Document Server

    Wang, Wenting; Henriques, Bruno M B; White, Simon D M

    2014-01-01

    We use the SDSS/DR8 galaxy sample to study the radial distribution of satellite galaxies around isolated primaries, comparing to semi-analytic models of galaxy formation based on the Millennium and Millennium-II simulations. SDSS satellites behave differently around high- and low-mass primaries: those orbiting objects with $M_*>10^{11}M_\\odot$ are mostly red and are less concentrated towards their host than the inferred dark matter halo, an effect that is very pronounced for the few blue satellites. On the other hand, less massive primaries have steeper satellite profiles that agree quite well with the expected dark matter distribution and are dominated by blue satellites, even in the inner regions where strong environmental effects are expected. In fact, such effects appear to be strong only for primaries with $M_* > 10^{11}M_\\odot$. This behaviour is not reproduced by current semi-analytic simulations, where satellite profiles always parallel those of the dark matter and satellite populations are predominan...

  14. GalICS II: the [alpha/Fe]-mass relation in elliptical galaxies

    CERN Document Server

    Pipino, A; Thomas, D; Silk, J; Kaviraj, S

    2008-01-01

    We aim at reproducing the mass- and sigma-[alpha/Fe] relations in the stellar populations of early-type galaxies by means of a cosmologically motivated assembly history for the spheroids. We implement a detailed treatment for the chemical evolution of H, He, O and Fe in GalICS, a semi-analytical model for galaxy formation which successfully reproduces basic low- and high-redshift galaxy properties. The contribution of supernovae (both type Ia and II) as well as low- and intermediate-mass stars to chemical feedback are taken into account. We find that this chemically improved GalICS does not produce the observed mass- and sigma-[alpha/Fe] relations. The slope is too shallow and scatter too large, in particular in the low and intermediate mass range. The model shows significant improvement at the highest masses and velocity dispersions, where the predicted [alpha/Fe] ratios are now marginally consistent with observed values. We show that this result comes from the implementation of AGN (plus halo) quenching of ...

  15. Manganese Dioxide nanosheet suspension: A novel absorbent for Cadmium(II) contamination in waterbody.

    Science.gov (United States)

    Peng, Liang; Zeng, Qingru; Tie, Boqing; Lei, Ming; Yang, Jiao; Luo, Si; Song, Zhengguo

    2015-10-15

    A MnO2 nanosheet (MnO2-NS) suspension was prepared from tetramethylammonium hydroxide (TMA⋅OH), H2O2, and MnCl2⋅4H2O, and its efficiency for Cd(II) removal from aqueous solutions was investigated. The maximum adsorption capacity of the MnO2-NS for Cd(II) was evaluated to be about 348 mg/g, which is thus far the highest value reported for MnO2 at pH 6.0. This high adsorption capacity is attributed to efficient ion exchange. X-ray photoelectron spectroscopy (XPS) revealed that Cd(II) was adsorbed on MnO2 as CdO and Cd(OH)2. After Cd(II) adsorption, the suspended MnO2-NS aggregated and precipitated within 5.0 min from solution. Therefore, dispersive MnO2-NS can be used to remove Cd(II) from wastewater rapidly and with high efficiency.

  16. X-Ray bright active galactic nuclei in massive galaxy clusters - II. The fraction of galaxies hosting active nuclei

    DEFF Research Database (Denmark)

    Ehlert, S.; von der Linden, A.; Allen, S. W.

    2013-01-01

    We present a measurement of the fraction of cluster galaxies hosting X-ray bright active galactic nuclei (AGN) as a function of clustercentric distance scaled in units of r500. Our analysis employs high-quality Chandra X-ray and Subaru optical imaging for 42 massive X-ray-selected galaxy cluster...

  17. Reconstructing the galaxy density field with photometric redshifts - II. Environment-dependent galaxy evolution since z ≃ 3

    Science.gov (United States)

    Malavasi, Nicola; Pozzetti, Lucia; Cucciati, Olga; Bardelli, Sandro; Ilbert, Olivier; Cimatti, Andrea

    2017-09-01

    Although extensively investigated, the role of the environment in galaxy formation is still not well understood. In this context, the galaxy stellar mass function (GSMF) is a powerful tool to understand how environment relates to galaxy mass assembly and the quenching of star formation. In this work, we make use of the high-precision photometric redshifts of the UltraVISTA Survey to study the GSMF in different environments up to z ∼ 3, on physical scales from 0.3 to 2 Mpc, down to masses of M ∼ 1010 M⊙. We witness the appearance of environmental signatures for both quiescent and star-forming galaxies. We find that the shape of the GSMF of quiescent galaxies is different in high- and low-density environments up to z ∼ 2 with the high-mass end (M ≳ 1011 M⊙) being enhanced in high-density environments. On the contrary, for star-forming galaxies, a difference between the GSMF in high- and low-density environments is present for masses M ≲ 1011 M⊙. Star-forming galaxies in this mass range appear to be more frequent in low-density environments up to z 2. Our results, in terms of general trends in the shape of the GSMF, are in agreement with a scenario in which galaxies are quenched when they enter hot gas-dominated massive haloes that are preferentially in high-density environments.

  18. Dark Matter Annihilation and Decay Profiles for the Reticulum II Dwarf Spheroidal Galaxy

    Science.gov (United States)

    Bonnivard, Vincent; Combet, Céline; Maurin, David; Geringer-Sameth, Alex; Koushiappas, Savvas M.; Walker, Matthew G.; Mateo, Mario; Olszewski, Edward W.; Bailey, John I., III

    2015-08-01

    The dwarf spheroidal galaxies (dSph) of the Milky Way are among the most attractive targets for indirect searches of dark matter (DM). In this work, we reconstruct the DM annihilation (J-factor) and decay profiles for the newly discovered dSph Reticulum II. Using an optimized spherical Jeans analysis of kinematic data obtained from the Michigan/Magellan Fiber System, we find Reticulum II’s J-factor to be among the largest of any Milky Way dSph. We have checked the robustness of this result against several ingredients of the analysis. Unless it suffers from tidal disruption or significant inflation of its velocity dispersion from binary stars, Reticulum II may provide a unique window on DM particle properties.

  19. Galaxy interactions in compact groups - II. Abundance and kinematic anomalies in HCG 91c

    Science.gov (United States)

    Vogt, Frédéric P. A.; Dopita, Michael A.; Borthakur, Sanchayeeta; Verdes-Montenegro, Lourdes; Heckman, Timothy M.; Yun, Min S.; Chambers, Kenneth C.

    2015-07-01

    Galaxies in Hickson Compact Group 91 (HCG 91) were observed with the WiFeS integral field spectrograph as part of our ongoing campaign targeting the ionized gas physics and kinematics inside star-forming members of compact groups. Here, we report the discovery of H II regions with abundance and kinematic offsets in the otherwise unremarkable star-forming spiral HCG 91c. The optical emission line analysis of this galaxy reveals that at least three H II regions harbour an oxygen abundance ˜0.15 dex lower than expected from their immediate surroundings and from the abundance gradient present in the inner regions of HCG 91c. The same star-forming regions are also associated with a small kinematic offset in the form of a lag of 5-10 km s-1 with respect to the local circular rotation of the gas. H I observations of HCG 91 from the Very Large Array and broad-band optical images from Pan-STARRS (Panoramic Survey Telescope And Rapid Response System) suggest that HCG 91c is caught early in its interaction with the other members of HCG 91. We discuss different scenarios to explain the origin of the peculiar star-forming regions detected with WiFeS, and show that evidence points towards infalling and collapsing extraplanar gas clouds at the disc-halo interface, possibly as a consequence of long-range gravitational perturbations of HCG 91c from the other group members. As such, HCG 91c provides evidence that some of the perturbations possibly associated with the early phase of galaxy evolution in compact groups impact the star-forming disc locally, and on sub-kpc scales.

  20. SHIELD II: AGC 198507 - An Extremely Rare Low-Mass Galaxy Interaction?

    Science.gov (United States)

    Nikolina Borg Stevens, Karin; Cannon, John M.; McNichols, Andrew; McQuinn, Kristen B.; Teich, Yaron; SHIELD II Team

    2016-01-01

    The "Survey of HI in Extremely Low-mass Dwarfs II" ("SHIELD II") is a multiwavelength, legacy-class observational campaign that is facilitating the study of both internal and global evolutionary processes in low-mass dwarf galaxies discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. New HST imaging of one of these sample galaxies, AGC 198507, has revealed it to be a very rare interacting system; to our knowledge this is one of only a few known interactions in this extreme mass range. WSRT imaging indicates that the bulk of the HI is associated with the more luminous AGC 198507, while low surface brightness gas extends toward and coincides with the less luminous companion, which is separated by roughly 1.5 kpc from AGC 198507. Here we present new VLA B configuration HI imaging that allows us to localize the HI gas, to examine the rotational dynamics of AGC 198507, and to study the nature of star formation in this unique low-mass interacting system.Support for this work was provided by NSF grant AST-1211683 to JMC at Macalester College, and by NASA through grant GO-13750 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.

  1. The Connections between QSO Absorption Systems and Galaxies: Low-Redshift Observations

    CERN Document Server

    Tripp, T M; Tripp, Todd M.; Bowen, David V.

    2005-01-01

    Quasar absorption lines have long been recognized to be a sensitive probe of the abundances, physical conditions, and kinematics of gas in a wide variety of environments including low-density intergalactic regions that probably cannot be studied by any other means. While some pre-Hubble Space Telescope (HST) observations indicated that Mg II absorption lines arise in gaseous galactic halos with a large covering factor, many early QSO absorber studies were hampered by a lack of information about the context of the absorbers and their connections with galaxies. By providing access to crucial ultraviolet resonance lines at low redshifts, deployment of HST and the Far Ultraviolet Spectroscopic Explorer enabled detailed studies of the relationships between QSO absorbers and galaxies. The advent of large surveys such as the Sloan Digital Sky Survey (SDSS) has also advanced the topic by greatly improving the size of absorber and galaxy samples. This paper briefly reviews some observational results on absorber-galaxy...

  2. Variable Stars in the Field of the Hydra II Ultra-faint Dwarf Galaxy

    Science.gov (United States)

    Vivas, A. Katherina; Olsen, Knut; Blum, Robert; Nidever, David L.; Walker, Alistair R.; Martin, Nicolas F.; Besla, Gurtina; Gallart, Carme; van der Marel, Roeland P.; Majewski, Steven R.; Kaleida, Catherine C.; Muñoz, Ricardo R.; Saha, Abhijit; Conn, Blair C.; Jin, Shoko

    2016-05-01

    We report the discovery of one RR Lyrae star in the ultra-faint satellite galaxy Hydra II based on time series photometry in the g, r and i bands obtained with the Dark Energy Camera at Cerro Tololo Inter-American Observatory, Chile. The association of the RR Lyrae star discovered here with Hydra II is clear because is located at 42\\prime\\prime from the center of the dwarf, well within its half-light radius of 102\\prime\\prime . The RR Lyrae star has a mean magnitude of i=21.30+/- 0.04 which is too faint to be a field halo star. This magnitude translates to a heliocentric distance of 151 ± 8 kpc for Hydra II; this value is ∼ 13% larger than the estimate from the discovery paper based on the average magnitude of several blue horizontal branch star candidates. The new distance implies a slightly larger half-light radius of {76}-10+12 pc and a brighter absolute magnitude of {M}V=-5.1+/- 0.3, which keeps this object within the realm of the dwarf galaxies. A comparison with other RR Lyrae stars in ultra-faint systems indicates similar pulsational properties among them, which are different to those found among halo field stars and those in the largest of the Milky Way satellites. We also report the discovery of 31 additional short period variables in the field of view (RR Lyrae, SX Phe, eclipsing binaries, and a likely anomalous cepheid) which are likely not related with Hydra II.

  3. The progenitors of present-day massive red galaxies up to z {\\approx} 0.7 - finding passive galaxies using SDSS-I/II and SDSS-III

    CERN Document Server

    Tojeiro, Rita; Wake, David A; Maraston, Claudia; Skibba, Ramin A; Zehavi, Idit; Ross, Ashley J; Conroy, Charlie; Guo, Hong; Manera, Marc; Masters, Karen L; Pforr, Janine; Samushia, Lado; Schneider, Donald P; Thomas, Daniel; Bizyaev, Dmitry; Brewington, Howard; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Pan, Kaike; Shelden, Alaina; Simmons, Audrey; Snedden, Stephanie

    2012-01-01

    We present a comprehensive study of 250,000 galaxies targeted by the Baryon Oscillation Spectroscopic Survey (BOSS) up to z {\\approx} 0.7 with the specific goal of identifying and characterising a population of galaxies that has followed passive evolution (no mergers) as closely as possible. We compute a likelihood that each BOSS galaxy is a progenitor of the Luminous Red Galaxies (LRGs) sample, targeted by SDSS-I/II up z {\\approx} 0.5, by using the fossil record of LRGs and their inferred star-formation histories, metallicity histories and dust content. We determine merger rates, luminosity growth rates and the evolution of the large-scale clustering between the two surveys, and we investigate the effect of using different stellar population synthesis models in our conclusions. We demonstrate that our sample is slowly evolving (of the order of 2 {\\pm} 1.5% Gyr-1 by merging) by computing the change in weighted luminosity-per-galaxy between the two samples, and that this result is robust to our choice of stell...

  4. A Multi-Wavelength Study of Low Redshift Cluster of Galaxies II. Environmental Impact on Galaxy Growth

    CERN Document Server

    Atlee, David W

    2012-01-01

    Galaxy clusters provide powerful laboratories for the study of galaxy evolution, particularly the origin of correlations of morphology and star formation rate (SFR) with density. We construct visible to MIR spectral energy distributions (SEDs) of cluster galaxies and use them to measure stellar masses and SFRs in eight low redshift clusters, which we examine as a function of environment. A partial correlation analysis indicates that SFR depends strongly on R/R200 (>99.9% confidence) and is independent of projected local density at fixed radius. SFR also shows no residual dependence on stellar mass. We therefore conclude that interactions with the intra-cluster medium drive the evolution of SFRs in cluster galaxies. A merged sample of galaxies from the five most complete clusters shows \\propto(R/R200)^(1.3+/-0.7) for galaxies with R/R200<0.4. A decline in the fraction of SFGs toward the cluster center contributes most of this effect, but it is accompanied by a reduction in SFRs among star-forming galaxies (...

  5. Selective paint coatings for coloured solar absorbers: Polyurethane thickness insensitive spectrally selective (TISS) paints (Part II)

    Energy Technology Data Exchange (ETDEWEB)

    Orel, B.; Spreizer, H.; Surca Vuk, A.; Fir, M. [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Merlini, D.; Vodlan, M. [Color d.d., Cesta komandanta Staneta 4, SI-1230 Medvode (Slovenia); Koehl, M. [Fraunhofer-Institute for Solar Energy Systems ISE, Heidenhofstr. 2, D-79110 Freiburg (Germany)

    2007-01-23

    Red, green and blue paints were prepared for use as thickness insensitive spectrally selective (TISS) paint coatings for solar facade absorbers. The paints were composed of a polyurethane resin binder in which various pigments were incorporated in such a way that they formed stable paint dispersions, satisfying stability criteria for facade coatings. A low emittance of the paints was achieved by using low-emittance aluminium flake pigments combined with iron oxide (red coloured paints). Black pigment was added to adjust solar absorptance. Blue and green paints were made by the addition of coloured aluminium flake pigment and the solar absorptance was also adjusted by the addition of black pigment. Efficiency for photo-thermal conversion of solar radiation was assessed by evaluation of the corresponding performance criteria, which enabled the selection of paints whose performance criteria values were higher than 0 (spectrally non-selective black coating). The results confirmed that blue and green paints and to minor extent red ones, combined selectivity with colour. The morphology of the paints was assessed, revealing that the colours originated from the deposition of finely dispersed colour and/or black pigment on the surface of the aluminium flakes during paint preparation. (author)

  6. Wheeler-Feynman Equations for Rigid Charges - Classical Absorber Electrodynamics Part II

    CERN Document Server

    Bauer, G; Dürr, D

    2010-01-01

    This is the second part of our mathematical survey on the equations of motion of classical absorber electrodynamics. Here we study the equations of Wheeler-Feynman (WF) electrodynamics, which describe the interaction of finitely many charges by both the advanced and retarded Li\\'enard-Wiechert fields. These equations are non-linear and involve retarded as well as advanced arguments and belong to the class of delay (or functional) differential equations. Such delayed arguments do not permit a direct application of standard PDE techniques. We introduce a general strategy to handle existence and uniqueness questions for such functional differential equations. We observe that any WF solution gives rise to a solution to the Maxwell-Lorentz equations without self-interaction (ML-SI), which are a set of non-linear PDEs without delay that have been studied in Part I. In other words, WF solutions are special solutions among all solutions of the ML-SI equations. Hence, WF solutions arise as solutions to the ML-SI equat...

  7. X-Ray bright active galactic nuclei in massive galaxy clusters - II. The fraction of galaxies hosting active nuclei

    DEFF Research Database (Denmark)

    Ehlert, S.; von der Linden, A.; Allen, S. W.

    2013-01-01

    We present a measurement of the fraction of cluster galaxies hosting X-ray bright active galactic nuclei (AGN) as a function of clustercentric distance scaled in units of r500. Our analysis employs high-quality Chandra X-ray and Subaru optical imaging for 42 massive X-ray-selected galaxy cluster......, both of which are also suppressed near cluster centres to a comparable extent. These results strongly support the idea that X-ray AGN activity and strong star formation are linked through their common dependence on available reservoirs of cold gas....... fields spanning the redshift range 0.2 cluster galaxy AGN fraction in the central...

  8. Galaxies Probing Galaxies: Cool Halo Gas from a z = 0.47 Post-Starburst Galaxy

    Science.gov (United States)

    Rubin, Kate H. R.; Prochaska, J. Xavier; Koo, David C.; Phillips, Andrew C.; Weiner, Benjamin J.

    2010-03-01

    We study the cool gas around a galaxy at z = 0.4729 using Keck/LRIS spectroscopy of a bright (B = 21.7) background galaxy at z = 0.6942 at a transverse distance of 16.5h -1 70 kpc. The background galaxy spectrum reveals strong Fe II, Mg II, Mg I, and Ca II absorption at the redshift of the foreground galaxy, with an Mg II λ2796 rest equivalent width of 3.93 ± 0.08 Å, indicative of a velocity width exceeding 400 km s-1. Because the background galaxy is large (>4h -1 70 kpc), the high covering fraction of the absorbing gas suggests that it arises in a spatially extended complex of cool clouds with large velocity dispersion. Spectroscopy of the massive (log M */M sun = 11.15 ± 0.08) host galaxy reveals that it experienced a burst of star formation about 1 Gyr ago and that it harbors a weak active galactic nucleus. We discuss the possible origins of the cool gas in its halo, including multiphase cooling of hot halo gas, cold inflow, tidal interactions, and galactic winds. We conclude that the absorbing gas was most likely ejected or tidally stripped from the interstellar medium of the host galaxy or its progenitors during the past starburst event. Adopting the latter interpretation, these results place one of only a few constraints on the radial extent of cool gas driven or stripped from a galaxy in the distant universe. Future studies with integral field unit spectroscopy of spatially extended background galaxies will provide multiple sight lines through foreground absorbers and permit analysis of the morphology and kinematics of the gas surrounding galaxies with a diverse set of properties and environments. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  9. The Mg II 2797, 2803 emission in low-metallicity star-forming galaxies from the SDSS

    CERN Document Server

    Guseva, N G; Fricke, K J; Henkel, C

    2013-01-01

    We present 65 Sloan Digital Sky Survey (SDSS) spectra of 62 star-forming galaxies with oxygen abundances 12 + logO/H ~ 7.5-8.4. Redshifts of selected galaxies are in the range z~0.36-0.70. This allows us to detect the redshifted MgII 2797,2803 emission lines. Our aim is to use these lines for the magnesium abundance determination. The MgII emission was detected in ~2/3 of the galaxies. We find that the MgII 2797 emission-line intensity follows a trend with the excitation parameter x= O^{2+}/O that is similar to that predicted by CLOUDY photoionised HII region models, suggesting a nebular origin of MgII emission. The Mg/O abundance ratio is lower by a factor ~2 than the solar ratio. This is probably the combined effect of interstellar MgII absorption and depletion of Mg onto dust. However, the effect of dust depletion in selected galaxies, if present, is small, by a factor of ~2 lower than that of iron.

  10. Dust-depletion sequences in damped Lyman-{\\alpha} absorbers: a unified picture from low-metallicity systems to the Galaxy

    CERN Document Server

    De Cia, Annalisa; Mattsson, Lars; Petitjean, Patrick; Srianand, Raghunathan; Gavignaud, Isabelle; Jenkins, Edward B

    2016-01-01

    We study metal depletion due to dust in the interstellar medium (ISM) to infer the properties of dust grains and characterize the metal and dust content of galaxies, down to low metallicity and intermediate redshift z. We provide metal column densities and abundances of a sample of 70 damped Lyman-{\\alpha} absorbers (DLAs) towards quasars, observed at high spectral resolution with the Very Large Telescope (VLT) Ultraviolet and Visual Echelle Spectrograph (UVES). This is the largest sample of phosphorus abundances measured in DLAs so far. We use literature measurements for Galactic clouds to cover the high-metallicity end. We discover tight (scatter <= 0.2 dex) correlations between [Zn/Fe] and the observed relative abundances, which are due to dust depletion. This implies that grain-growth in the ISM is an important process of dust production. These sequences are continuous in [Zn/Fe] from dust-free to dusty DLAs, and to Galactic clouds, suggesting that the availability of refractory metals in the ISM is cr...

  11. Simultaneous Ultraviolet and X-ray Observations of the Seyfert Galaxy NGC 4151. I. Physical Conditions in the X-ray Absorbers

    CERN Document Server

    Krämer, S B; Crenshaw, D M; Gabel, J R; Turner, T J; Gull, T R; Hutchings, J B; Kriss, G A; Mushotzky, R F; Netzer, H; Peterson, B M; Behar, E; Behar, Ehud

    2005-01-01

    We present a detailed analysis of the intrinsic X-ray absorption in the Seyfert 1 galaxy NGC 4151 using Chandra/HETGS data obtained 2002 May, as part of a program which included simultaneous UV spectra using HST/STIS and FUSE. NGC 4151 was in a relatively low flux state during the observations reported here, although roughly 2.5 times as bright in the 2 --10 keV band as during a Chandra observation in 2000. The soft X-ray band was dominated by emission lines, which show no discernible variation in flux between the two observations. The 2002 data show the presence of a very highly ionized absorber, in the form of H-like and He-like Mg, Si, and S lines, as well as lower ionization gas via the presence of inner-shell absorption lines from lower-ionization species of these elements. The former is too highly ionized to be radiatively accelerated in a sub-Eddington source such as NGC 4151. We find that the lower ionization gas had a column density a factor of ~ 3 higher during the 2000 observation. If due to bulk m...

  12. Probing highly-obscured galaxy nuclei with vibrationally excited HCN - Extreme luminosity densities inside self-absorbed v=0 HCN and HCO+

    CERN Document Server

    Aalto, S; Gonzalez-Alfonso, E; Muller, S; Sakamoto, K; Fuller, G A; Garcia-Burillo, S; van der Werf, P; Neri, R; Spaans, M; Combes, F; Viti, S; Muehle, S; Armus, L; Evans, A; Sturm, E; Cernicharo, J; Henkel, C; Greve, T R

    2015-01-01

    We present high resolution (0."4) IRAM PdBI and ALMA mm and submm observations of the (Ultra) Luminous Infrared Galaxies ((U)LIRGs) IRAS17208-0014, Arp220, IC860 and Zw049.057 that reveal intense line emission from vibrationally excited (v2=1) J=3-2 and 4-3 HCN. The emission is emerging from buried, compact (r5e13 Lsun/kpc2. These nuclei are likely powered by accreting supermassive black holes (SMBHs) and/or hot (>200 K) extreme starbursts. Vibrational, v2=1, lines of HCN are excited by intense 14 micron mid-infrared emission and are excellent probes of the dynamics, masses and physical conditions of (U)LIRG nuclei when H2 column densities exceed 1e24 cm-2. It is clear that these lines open up a new interesting avenue to gain access to the most obscured AGNs and starbursts. Vibrationally excited HCN acts as a proxy for the absorbed mid-infrared emission from the embedded nuclei, which allows for reconstruction of the intrinsic, hotter dust SED. In contrast, the ground vibrational state (v=0), J=3-2 and 4-3 ro...

  13. The Chandra High Energy Transmission Grating Spectrometer probes the dusty warm absorber in the Seyfert 1 galaxy MCG--6-30-15

    CERN Document Server

    Lee, J C; Marshall, H L; Fabian, A C; Morales, R; Schulz, N S; Iwasawa, K

    2001-01-01

    The Chandra HETGS spectra of the Seyfert 1 galaxy MCG--6-30-15 show numerous narrow, unresolved (FWHM 0.48 keV (< 26 A). We attribute previous reports of an apparently highly redshifted O VII edge to the neutral Fe L absorption complex and the O VII resonance series (by transitions higher than He $\\gamma$; He $\\alpha,\\beta,\\gamma$ are also seen at lower energies). The implied dust column density needed to explain the FeI L edge feature agrees with that obtained from earlier reddening studies, which had already concluded that the dust should be associated with the ionized absorber (given the relatively lower observed X-ray absorption by cold gas). Our findings contradict the interpretation of Branduardi-Raymont et al. (2001), based on XMM-Newton RGS spectra, that this spectral region is dominated by highly relativistic soft X-ray line emission originating near the central black hole. Here we review these issues pertaining to the soft X-ray spectral features as addressed by Lee et al., (2001). (Details foun...

  14. AGN Jet Power, Formation of X-ray Cavities, and FR I/II Dichotomy in Galaxy Clusters

    CERN Document Server

    Fujita, Yutaka; Shlosman, Isaac

    2016-01-01

    We investigate the ability of jets in active galactic nuclei (AGNs) to break out of the ambient gas with sufficiently large advance velocities. Using observationally estimated jet power, we analyze 28 bright elliptical galaxies in nearby galaxy clusters. Because the gas density profiles in the innermost regions of galaxies have not been resolved so far, we consider two extreme cases for temperature and density profiles. We also follow two types of evolution for the jet cocoons: being driven by the pressure inside the cocoon (Fanaroff-Riley [FR] I type), and being driven by the jet momentum (FR II type). Our main result is that regardless of the assumed form of density profiles, jets with observed powers of ~ 10^{44} erg s^{-1} are less affected by the ambient medium, and some of them, but not all, could serve as precursors of the FR II sources.

  15. The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II)\\\\ II. Construction and Properties of the Survey

    CERN Document Server

    Böhringer, Hans; Collins, Chris A; Guzzo, Luigi; Nowak, Nina; Bobrovskyi, Sergei

    2014-01-01

    Galaxy clusters provide unique laboratories to study astrophysical processes on large scales and are important probes for cosmology. X-ray observations are currently the best means of detecting and characterizing galaxy clusters. In this paper we describe the construction of the REFLEX II galaxy cluster survey based on the southern part of the ROSAT All-Sky Survey. REFLEX II extends the REFLEX I survey by a factor of about two down to a flux limit of $1.8 \\times 10^{-12}$ erg s$^{-1}$ cm$^{-2}$ (0.1 - 2.4 keV). We describe the determination of the X-ray parameters, the process of X-ray source identification, and the construction of the survey selection function. The REFLEX II cluster sample comprises currently 915 objects. A standard selection function is derived for a lower source count limit of 20 photons in addition to the flux limit. The median redshift of the sample is $z = 0.102$. Internal consistency checks and the comparison to several other galaxy cluster surveys imply that REFLEX II is better than 9...

  16. Escape of ionizing radiation from star-forming regions in Young galaxies

    DEFF Research Database (Denmark)

    Razoumov, A; Sommer-Larsen, Jesper

    2006-01-01

    Galaxies: Formation, Galaxies: Intergalactic Medium, ISM: H II Regions, Radiative Transfer Udgivelsesdato: Nov. 10......Galaxies: Formation, Galaxies: Intergalactic Medium, ISM: H II Regions, Radiative Transfer Udgivelsesdato: Nov. 10...

  17. The NIR Ca II triplet at low metallicity : Searching for extremely low-metallicity stars in classical dwarf galaxies

    NARCIS (Netherlands)

    Starkenburg, E.; Hill, V.; Tolstoy, E.; Gonzalez Hernandez, J.I.; Irwin, M.; Helmi, A.; Battaglia, G.; Jablonka, P.; Tafelmeyer, M.; Shetrone, M.; Venn, K.; de Boer, T.

    2010-01-01

    The NIR Ca II triplet absorption lines have proven to be an important tool for quantitative spectroscopy of individual red giant branch stars in the Local Group, providing a better understanding of metallicities of stars in the Milky Way and dwarf galaxies and thereby an opportunity to constrain the

  18. Hydra II: A Faint and Compact Milky Way Dwarf Galaxy Found in the Survey of the Magellanic Stellar History

    NARCIS (Netherlands)

    Martin, Nicolas F.; Nidever, David L.; Besla, Gurtina; Olsen, Knut; Walker, Alistair R.; Vivas, A. Katherina; Gruendl, Robert A.; Kaleida, Catherine C.; Muñoz, Ricardo R.; Blum, Robert D.; Saha, Abhijit; Conn, Blair C.; Bell, Eric F.; Chu, You-Hua; Cioni, Maria-Rosa L.; de Boer, Thomas J. L.; Gallart, Carme; Jin, Shoko; Kunder, Andrea; Majewski, Steven R.; Martinez-Delgado, David; Monachesi, Antonela; Monelli, Matteo; Monteagudo, Lara; Noël, Noelia E. D.; Olszewski, Edward W.; Stringfellow, Guy S.; van der Marel, Roeland P.; Zaritsky, Dennis

    We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the Magellanic Stellar History conducted with the Dark Energy Camera on the Blanco 4 m Telescope. The new satellite is compact ({{r}h}=68 ± 11 pc) and faint ({{M}V}=-4.8 ± 0.3),

  19. Proper Motion of the Leo II Dwarf Galaxy Based On Hubble Space Telescope Imaging

    CERN Document Server

    Piatek, Slawomir; Olszewski, Edward W

    2016-01-01

    This article reports a measurement of the proper motion of Leo II, a dwarf galaxy that is a likely satellite of the Milky Way, based on imaging with the Hubble Space Telescope and Wide Field Camera 3. The measurement uses compact background galaxies as standards of rest in both channels of the camera for two distinct pointings of the telescope and a QSO in one channel for each pointing, resulting in the weighted average of six measurements. The measured proper motion in the the equatorial coordinate system is (mu_alpha, mu_delta) = (-6.9 +- 3.7, -8.7 +- 3.9) mas/century and in the Galactic coordinate system is (mu_l, mu_b) = (6.2 +- 3.9, -9.2 +- 3.7) mas/century. The implied space velocity with respect to the Galactic center is (Pi, Theta, Z) = (-37 +- 38, 117 +- 43, 40 +- 16) km/s or, expressed in Galactocentric radial and tangential components, (V_r, V_tan) = (21.9 +- 1.5, 127 +- 42) km/s. The space velocity implies that the instantaneous orbital inclination is 68 degrees, with a 95% confidence interval of ...

  20. On the efficiency of jet production in FR II radio galaxies and quasars

    Science.gov (United States)

    Rusinek, Katarzyna; Sikora, Marek; Kozieł-Wierzbowska, Dorota; Godfrey, Leith

    2017-04-01

    Jet powers in many radio galaxies with extended radio structures appear to exceed their associated accretion luminosities. In systems with very low accretion rates, this is likely due to the very low accretion luminosities resulting from radiatively inefficient accretion flows. In systems with high accretion rates, the accretion flows are expected to be radiatively efficient, and the production of such powerful jets may require an accretion scenario, which involves magnetically arrested discs (MADs). However, numerical simulations of the MAD scenario indicate that jet production efficiency is large only for geometrically thick accretion flows and scales roughly with (H/R)2, where H is the disc height and R is the distance from the black hole. Using samples of FR II radio galaxies and quasars accreting at moderate accretion rates, we show that their jets are much more powerful than predicted by the MAD scenario. We discuss possible origins of this discrepancy, suggesting that it can be related to approximations adopted in magnetohydrodynamic simulations to treat optically thick accretion flow within the MAD zone, or may indicate that accretion discs are geometrically thicker than the standard theory predicts.

  1. Galaxy gas as obscurer - II. Separating the galaxy-scale and nuclear obscurers of active galactic nuclei

    Science.gov (United States)

    Buchner, Johannes; Bauer, Franz E.

    2017-03-01

    The 'torus' obscurer of active galactic nuclei (AGN) is poorly understood in terms of its density, sub-structure and physical mechanisms. Large X-ray surveys provide model boundary constraints, for both Compton-thin and Compton-thick levels of obscuration, as obscured fractions are mean covering factors fcov. However, a major remaining uncertainty is host-galaxy obscuration. In Paper I, we discovered a relation of {NH} ∝ M_{star }^{1/3} for the obscuration of galaxy-scale gas. Here, we apply this observational relation to the AGN population, and find that galaxy-scale gas is responsible for a luminosity-independent fraction of Compton-thin AGN, but does not produce Compton-thick columns. With the host-galaxy obscuration understood, we present a model of the remaining nuclear obscurer, which is consistent with a range of observations. Our radiation-lifted torus model consists of a Compton-thick component (fcov ∼ 35 per cent) and a Compton-thin component (fcov ∼ 40 per cent), which depends on both black hole mass and luminosity. This provides a useful summary of observational constraints for torus modellers who attempt to reproduce this behaviour. It can also be employed as a sub-grid recipe in cosmological simulations that do not resolve the torus. We also investigate host-galaxy X-ray obscuration inside cosmological, hydrodynamic simulations (Evolution and Assembly of Galaxies and their Environment; Illustris). The obscuration from ray-traced galaxy gas can agree with observations, but is highly sensitive to the chosen feedback assumptions.

  2. Ultrafast excited state dynamics of Pt(II) chromophores bearing multiple infrared absorbers.

    Science.gov (United States)

    Glik, Elena A; Kinayyigit, Solen; Ronayne, Kate L; Towrie, Michael; Sazanovich, Igor V; Weinstein, Julia A; Castellano, Felix N

    2008-08-04

    The paper reports the synthesis, structural characterization, electrochemistry, ultrafast time-resolved infrared (TRIR) and transient absorption (TA) spectroscopy associated with two independent d (8) square planar Pt(II) diimine chromophores, Pt(dnpebpy)Cl 2 ( 1) and Pt(dnpebpy)(C[triple bond]Cnaph) 2 ( 2), where dnpebpy = 4,4'-(CO 2CH 2- (t) Bu) 2-2,2'-bipyridine and CCnaph = naphthylacetylide. The neopentyl ester substitutions provided markedly improved complex solubility relative to the corresponding ethyl ester which facilitates synthetic elaboration as well as spectroscopic investigations. Following 400 nm pulsed laser excitation in CH 2Cl 2, the 23 cm (-1) red shift in the nu C=O vibrations in 1 are representative of a complex displaying a lowest charge-transfer-to-diimine (CT) excited state. The decay kinetics in 1 are composed of two time constants assigned to vibrational cooling of the (3)CT excited-state concomitant with its decay to the ground state (tau = 2.2 +/- 0.4 ps), and to cooling of the formed vibrationally hot ground electronic state (tau = 15.5 +/- 4.0 ps); we note that an assignment of the latter to a ligand field state cannot be excluded. Ultrafast TA data quantitatively support these assignments yielding an excited-state lifetime of 2.7 +/- 0.4 ps for the (3)CT excited-state of 1 and could not detect any longer-lived species. The primary intention of this study was to develop a Pt (II) complex ( 2) bearing dual infrared spectroscopic tags (C[triple bond]C attached to the metal and CO (ester) attached to the diimine ligand) to independently track the movement of charge density in different segments of the molecule following pulsed light excitation. Femtosecond laser excitation of 2 in CH 2Cl 2 at 400 nm simultaneously induces a red-shift in both the nu C=O (-30 cm (-1)) and the nu C[triple bond]C (-61 cm (-1)) vibrations. The TRIR data in 2 are consistent with a charge transfer assignment, and the significant decrease of the energy of the nu

  3. HIGH-RESOLUTION SPECTROSCOPY OF EXTREMELY METAL-POOR STARS IN THE LEAST EVOLVED GALAXIES: BOÖTES II

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Alexander P.; Frebel, Anna [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Simon, Joshua D. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101 (United States); Geha, Marla, E-mail: alexji@mit.edu [Astronomy Department, Yale University, New Haven, CT 06520 (United States)

    2016-01-20

    We present high-resolution Magellan/MIKE spectra of the four brightest confirmed red giant stars in the ultra-faint dwarf galaxy Boötes II (Boo II). These stars all inhabit the metal-poor tail of the Boo II metallicity distribution function. The chemical abundance pattern of all detectable elements in these stars is consistent with that of the Galactic halo. However, all four stars have undetectable amounts of neutron-capture elements Sr and Ba, with upper limits comparable to the lowest ever detected in the halo or in other dwarf galaxies. One star exhibits significant radial velocity variations over time, suggesting it to be in a binary system. Its variable velocity has likely increased past determinations of the Boo II velocity dispersion. Our four stars span a limited metallicity range, but their enhanced α-abundances and low neutron-capture abundances are consistent with the interpretation that Boo II has been enriched by very few generations of stars. The chemical abundance pattern in Boo II confirms the emerging trend that the faintest dwarf galaxies have neutron-capture abundances distinct from the halo, suggesting the dominant source of neutron-capture elements in halo stars may be different than in ultra-faint dwarfs.

  4. The Subaru FMOS Galaxy Redshift Survey (FastSound). II. The Emission Line Catalog and Properties of Emission Line Galaxies

    CERN Document Server

    Okada, Hiroyuki; Tonegawa, Motonari; Akiyama, Masayuki; Dalton, Gavin; Glazebrook, Karl; Iwamuro, Fumihide; Ohta, Kouji; Takato, Naruhisa; Tamura, Naoyuki; Yabe, Kiyoto; Bunker, Andrew J; Goto, Tomotsugu; Hikage, Chiaki; Ishikawa, Takashi; Okumura, Teppei; Shimizu, Ikkoh

    2015-01-01

    We present basic properties of $\\sim$3,300 emission line galaxies detected by the FastSound survey, which are mostly H$\\alpha$ emitters at $z \\sim$ 1.2-1.5 in the total area of about 20 deg$^2$, with the H$\\alpha$ flux sensitivity limit of $\\sim 1.6 \\times 10^{-16} \\rm erg \\ cm^{-2} s^{-1}$ at 4.5 sigma. This paper presents the catalogs of the FastSound emission lines and galaxies, which will be open to the public in the near future. We also present basic properties of typical FastSound H$\\alpha$ emitters, which have H$\\alpha$ luminosities of $10^{41.8}$-$10^{43.3}$ erg/s, SFRs of 20--500 $M_\\odot$/yr, and stellar masses of $10^{10.0}$--$10^{11.3}$ $M_\\odot$. The 3D distribution maps for the four fields of CFHTLS W1--4 are presented, clearly showing large scale clustering of galaxies at the scale of $\\sim$ 100--600 comoving Mpc. Based on 1,105 galaxies with detections of multiple emission lines, we estimate that contamination of non-H$\\alpha$ lines is about 4% in the single-line emission galaxies, which are m...

  5. HI Selected Galaxies in the Sloan Digital Sky Survey II: The Colors of Gas-Rich Galaxies

    CERN Document Server

    West, Andrew A; Dalcanton, Julianne J; Disney, Mike J; Rockosi, Constance R; Ivezic, Zeljko

    2009-01-01

    We utilize color information for an HI-selected sample of 195 galaxies to explore the star formation histories and physical conditions that produce the observed colors. We show that the HI selection creates a significant offset towards bluer colors that can be explained by enhanced recent bursts of star formation. There is also no obvious color bimodality, because the HI selection restricts the sample to bluer, actively star forming systems, diminishing the importance of the red sequence. Rising star formation rates are still required to explain the colors of galaxies bluer than g-r < 0.3. We also demonstrate that the colors of the bluest galaxies in our sample are dominated by emission lines and that stellar population synthesis models alone (without emission lines) are not adequate for reproducing many of the galaxy colors. These emission lines produce large changes in the r-i colors but leave the g-r color largely unchanged. In addition, we find an increase in the dispersion of galaxy colors at low mass...

  6. A Herschel Survey of the [N II] 205 micron Line in Local Luminous Infrared Galaxies --- The [N II] 205 micron Emission as a Star Formation Rate Indicator

    CERN Document Server

    Zhao, Yinghe; Xu, C Kevin; Gao, Yu; Lord, S; Howell, J; Isaak, K G; Charmandaris, V; Diaz-Santos, T; Appleton, P; Evans, A; Iwasawa, K; Leech, J; Mazzarella, J; Petric, A O; Sanders, D B; Schulz, B; Surace, J; van der Werf, P P

    2013-01-01

    We present, for the first time, a statistical study of [N II] 205 mciron line emission for a large sample of local luminous infrared galaxies using Herschel Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (SPIRE FTS) data. For our sample of galaxies, we investigate the correlation between the [N II] luminosity (LNII) and the total infrared luminosity (LIR), as well as the dependence of LNII/LIR ratio on LIR, far infrared colors (IRAS $f_{60}/f_{100}$) and the [O III] 88 micron to [N II] luminosity ratio. We find that LNII correlates almost linearly with LIR for non AGN galaxies (all having $L_{IR} < 10^{12} L_solar$) in our sample, which implies that LNII can serve as a SFR tracer which is particularly useful for high redshift galaxies which will be observed with forthcoming submm spectroscopic facilities such as the Atacama Large Millimeter/submillimeter Array. Our analysis shows that the deviation from the mean LNII-LIR relation correlates with tracers of the ionization parameter...

  7. LOSS Revisited. II. The Relative Rates of Different Types of Supernovae Vary between Low- and High-mass Galaxies

    Science.gov (United States)

    Graur, Or; Bianco, Federica B.; Modjaz, Maryam; Shivvers, Isaac; Filippenko, Alexei V.; Li, Weidong; Smith, Nathan

    2017-03-01

    In Paper I of this series, we showed that the ratio between stripped-envelope (SE) supernova (SN) and Type II SN rates reveals a significant SE SN deficiency in galaxies with stellar masses ≲ {10}10 {M}ȯ . Here, we test this result by splitting the volume-limited subsample of the Lick Observatory Supernova Search (LOSS) SN sample into low- and high-mass galaxies and comparing the relative rates of various SN types found in them. The LOSS volume-limited sample contains 180 SNe and SN impostors and is complete for SNe Ia out to 80 Mpc and core-collapse SNe out to 60 Mpc. All of these transients were recently reclassified by us in Shivvers et al. We find that the relative rates of some types of SNe differ between low- and high-mass galaxies: SNe Ib and Ic are underrepresented by a factor of ∼3 in low-mass galaxies. These galaxies also contain the only examples of SN 1987A-like SNe in the sample and host about nine times as many SN impostors. Normal SNe Ia seem to be ∼30% more common in low-mass galaxies, making these galaxies better sources for homogeneous SN Ia cosmology samples. The relative rates of SNe IIb are consistent in both low- and high-mass galaxies. The same is true for broad-line SNe Ic, although our sample includes only two such objects. The results presented here are in tension with a similar analysis from the Palomar Transient Factory, especially as regards SNe IIb.

  8. Galaxy clustering dependence on the $\\left[\\mathrm{O\\scriptsize{II}}\\right]$ emission line luminosity in the local Universe

    CERN Document Server

    Favole, Ginevra; Comparat, Johan; Prada, Francisco; Guo, Hong; Klypin, Anatoly; Montero-Dorta, Antonio D

    2016-01-01

    We study the galaxy clustering dependence on the $\\left[\\mathrm{O\\scriptsize{II}}\\right]$ emission line luminosity in the SDSS DR7 Main galaxy sample at mean redshift $z\\sim0.1$. We select volume-limited samples of galaxies with different $\\left[\\mathrm{O\\scriptsize{II}}\\right]$ luminosity thresholds and measure their projected, monopole and quadrupole two-point correlation functions. We model these observations using the 1$h^{-1}\\rm{Gpc}$ MultiDark Planck cosmological simulation and generate light-cones with the SUrvey GenerAtoR algorithm. To interpret our results, we adopt a modified (Sub)Halo Abundance Matching scheme, accounting for the stellar mass incompleteness of the emission line galaxies. The satellite fraction constitutes an extra parameter in this model and allows to optimize the clustering fit on both small and intermediate scales (i.e. $r_p\\lesssim 30h^{-1}\\rm{Mpc})$, with no need of any velocity bias correction. We find that, in the local Universe, the $\\left[\\mathrm{O\\scriptsize{II}}\\right]$ l...

  9. The role of Fanaroff-Riley II radio galaxies in the acceleration of the most energetic cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Massaglia, S. [Dipartimento di Fisica Generale dell' Universita, 10125 Torino (Italy)

    2007-06-15

    Possible sources of ultra-high energy cosmic rays are the hot-spots of Fanaroff-Riley II radio galaxies. In fact, these regions meet the requirements of size, magnetic field intensity and presence of strong shocks for accelerating particles up to energies that exceed 10{sup 21} eV. On the other hand, the interaction with the photons of the Cosmic Microwave Background radiation, the Greisen-Zatsepin-Kuz'min effect, dictates that the sources of particles with energy above 4x10{sup 19} eV must be within 130 Mpc, at most. There are not very many FR II radio galaxies within this distance, i.e. 15 objects. Once the statistics of events for detection of cosmic rays at these energies will have reached reasonable levels looking for the arrival directions will either confirm or rule out the FR II hot-spots as sources of ultra-high energy cosmic rays.

  10. Galaxy gas as obscurer: II. Separating the galaxy-scale and nuclear obscurers of Active Galactic Nuclei

    CERN Document Server

    Buchner, Johannes

    2016-01-01

    The "torus" obscurer of Active Galactic Nuclei (AGN) is poorly understood in terms of its density, substructure and physical mechanisms. Large X-ray surveys provide model boundary constraints, for both Compton-thin and Compton-thick levels of obscuration, as obscured fractions are mean covering factors $f_{\\text{cov}}$. However, a major remaining uncertainty is host galaxy obscuration. In Paper I we discovered a relation of $N_H \\propto M_{\\star}^{1/3}$ for the obscuration of galaxy-scale gas. Here we apply this observational relation to the AGN population, and find that galaxy-scale gas is responsible for a luminosity-independent fraction of Compton-thin AGN, but does not produce Compton-thick columns. With the host galaxy obscuration understood, we present a model of the remaining, nuclear obscurer which is consistent with a range of observations. Our radiation-lifted torus model consists of a Compton-thick component ($f_{\\text{cov}}\\sim35\\%$) and a Compton-thin component ($f_{\\text{cov}}\\sim40\\%$), which d...

  11. The potential of the dwarf galaxy Triangulum II for dark matter indirect detection

    Science.gov (United States)

    Genina, Anna; Fairbairn, Malcolm

    2016-12-01

    The recently discovered object Triangulum II appears to be an ultrafaint dwarf spheroidal galaxy which may be one of the most dark-matter-dominated objects yet known. In this work we try to estimate the potential of this object for studies of the indirect detection of self-annihilating dark matter by obtaining its astrophysical J-factor. We perform a basic estimate of the velocity gradient to look for signs of the halo being tidally disrupted but show that the observed value is statistically compatible with zero velocity gradient. We solve the spherical Jeans equation using Markov chain Monte Carlo engine GreAT and the Jeans analysis part of the CLUMPY package. We find the results point towards a very large J-factor, appearing to make Triangulum II one of the best targets in the search for dark matter. However we stress that the very small number of line of sight velocities currently available for this object make follow-up studies essential.

  12. The Estimate of Kinetic Power of Jets in FR II Radio Galaxies: Existence of Invisible Components?

    Science.gov (United States)

    Ito, Hirotaka; Kino, Motoki; Kawakatu, Nozomu; Isobe, Naoki; Yamada, Shoichi

    2008-10-01

    We investigate the total kinetic power (Lj) and age (tage) of powerful jets in FR II radio galaxies by comparison of the dynamical model of expanding cocoons with observations. We select four FR II radio sources (Cygnus A, 3C 223, 3C 284, and 3C 219), for which the mass-density profiles of the intracluster medium (ICM) are known in the literature. It is found that large fractions gtrsim0.02-0.7 of the Eddington luminosity (LEdd) are carried away as kinetic power of jets. The upper limit of estimated 2Lj/LEdd is larger than unity (lesssim10) for some sources, suggesting the possibility of super-Eddington mass accretions. As a consequence of the large powers, we also find that the total energy stored in the cocoon (Ec) exceeds the energy derived from the minimum energy condition for the energy of radiating nonthermal electrons and magnetic fields (Emin): 4 < Ec/Emin < 310. This implies that most of the energy in the cocoon is carried by invisible components such as thermal leptons (electron and positron) and/or protons.

  13. Massive Star Formation in a Gravitationally-Lensed H II Galaxy at z = 3.357

    Energy Technology Data Exchange (ETDEWEB)

    Villar-Martin, M; Stern, D; Hook, R N; Rosati, P; Lombardi, M; Humphrey, A; Fosbury, R; Stanford, S A; Holden, B P

    2004-03-02

    The Lynx arc, with a redshift of 3.357, was discovered during spectroscopic follow-up of the z = 0.570 cluster RX J0848+4456 from the ROSAT Deep Cluster Survey. The arc is characterized by a very red R - K color and strong, narrow emission lines. Analysis of HST WFPC 2 imaging and Keck optical and infrared spectroscopy shows that the arc is an H II galaxy magnified by a factor of {approx} 10 by a complex cluster environment. The high intrinsic luminosity, the emission line spectrum, the absorption components seen in Ly{alpha} and C IV, and the restframe ultraviolet continuum are all consistent with a simple H II region model containing {approx} 10{sup 6} hot O stars. The best fit parameters for this model imply a very hot ionizing continuum (T{sub BB} {approx} 80, 000 K), high ionization parameter (log U {approx} -1), and low nebular metallicity (Z/Z{sub {circle_dot}} {approx} 0.05). The narrowness of the emission lines requires a low mass-to-light ratio for the ionizing stars, suggestive of an extremely low metallicity stellar cluster. The apparent overabundance of silicon in the nebula could indicate enrichment by past pair instability supernovae, requiring stars more massive than {approx}140M{sub {circle_dot}}.

  14. SNe Ia host galaxy properties from Sloan Digital Sky Survey-II spectroscopy

    CERN Document Server

    Johansson, Jonas; Pforr, Janine; Maraston, Claudia; Nichol, Robert C; Smith, Mathew; Lampeitl, Hubert; Beifiori, Alessandra; Gupta, Ravi R; Schneider, Donald P

    2012-01-01

    We study the stellar populations of SNe Ia host galaxies using SDSS-II spectroscopy. We focus on the relationships of SNe Ia properties with stellar velocity dispersion and the stellar population parameters age, metallicity and element abundance ratios derived by fitting absorption line indices to stellar population models. We concentrate on a sub-sample of 84 SNe Ia from the SDSS-II Supernova Survey. In agreement with previous findings, we find that SALT2 stretch factor values show the strongest dependence on stellar population age. Hence, SNe Ia peak-luminosity is closely related to the age of the stellar progenitor systems, where more luminous SNe Ia appear in younger stellar populations. We find no statistically significant trends in the Hubble residual with any of the stellar population parameters studied, including age and metallicity contrary to the literature, as well as with stellar velocity dispersion. Moreover, we find that the method of stellar mass derivation is affecting the Hubble residual-mass...

  15. The Highly Ionized Circumgalactic Medium is Kinematically Uniform Around Galaxies

    CERN Document Server

    Nielsen, Nikole M; Muzahid, Sowgat; Churchill, Christopher W; Murphy, Michael T; Charlton, Jane C

    2016-01-01

    The circumgalactic medium (CGM) traced by OVI $\\lambda\\lambda 1031, 1037$ doublet absorption has been found to concentrate along the projected major and minor axes of the host galaxies. This suggests that OVI traces accreting and outflowing gas, respectively, which are key components of the baryon cycle of galaxies. We investigate this further by examining the kinematics of 29 OVI absorbers associated with galaxies at $0.13 < z_{\\rm gal} < 0.66$ as a function of galaxy color, inclination, and azimuthal angle. Each galaxy was imaged with HST and the absorption was detected in COS/HST spectra of nearby ($D<200$ kpc) background quasars. We use the pixel-velocity two-point correlation function to characterize the velocity spread of the absorbers, which is a method used previously for a sample of MgII absorber--galaxy pairs. The absorption velocity spread for OVI is more extended than MgII, which suggests that the two ions trace differing components of the CGM. Also contrary to MgII, the OVI absorption ve...

  16. The HETDEX Pilot Survey. IV. The Evolution of [O II] Emitting Galaxies from z ~ 0.5 to z ~ 0

    CERN Document Server

    Ciardullo, Robin; Adams, Joshua J; Blanc, Guillermo A; Gebhardt, Karl; Finkelstein, Steven L; Jogee, Shardha; Hill, Gary J; Drory, Niv; Hopp, Ulrich; Schneider, Donald P; Zeimann, Gregory R; Dalton, Gavin B

    2013-01-01

    We present an analysis of the luminosities and equivalent widths of the 284 z < 0.56 [O II]-emitting galaxies found in the 169 square arcmin pilot survey for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). By combining emission-line fluxes obtained from the Mitchell spectrograph on the McDonald 2.7-m telescope with deep broadband photometry from archival data, we derive each galaxy's de-reddened [O II] 3727 luminosity and calculate its total star formation rate. We show that over the last ~5 Gyr of cosmic time there has been substantial evolution in the [O II] emission-line luminosity function, with L* decreasing by ~0.6 +/-0.2 dex in the observed function, and by ~0.9 +/-0.2 dex in the de-reddened relation. Accompanying this decline is a significant shift in the distribution of [O II] equivalent widths, with the fraction of high equivalent-width emitters declining dramatically with time. Overall, the data imply that the relative intensity of star formation within galaxies has decreased over th...

  17. A photometric survey for Lyalpha-HeII dual emitters: Searching for Population III stars in high-redshift galaxies

    CERN Document Server

    Nagao, Tohru; Maiolino, Roberto; Grady, Celestine; Kashikawa, Nobunari; Ly, Chun; Malkan, Matthew; Motohara, Kentaro; Murayama, Takashi; Schaerer, Daniel; Shioya, Yasuhiro; Taniguchi, Yoshiaki

    2008-01-01

    We present a new photometric search for high-z galaxies hosting Population III (PopIII) stars based on deep intermediate-band imaging observations obtained in the Subaru Deep Field (SDF), by using Suprime-Cam on the Subaru Telescope. By combining our new data with the existing broad-band and narrow-band data, we searched for galaxies which emit strongly both in Ly_alpha and in HeII 1640 (``dual emitters'') that are promising candidates for PopIII-hosting galaxies, at 3.93 2 Msun/yr was found by our photometric search in 4.03 x 10^5 Mpc^3 in the SDF. This result disfavors low feedback models for PopIII star clusters, and implies an upper-limit of the PopIII SFR density of SFRD_PopIII < 5 x 10^-6 Msun/yr/Mpc^3. This new selection method to search for PopIII-hosting galaxies should be useful in future narrow-band surveys to achieve the first observational detection of PopIII-hosting galaxies at high redshifts.

  18. LOSS Revisited - II: The relative rates of different types of supernovae vary between low- and high-mass galaxies

    CERN Document Server

    Graur, Or; Modjaz, Maryam; Shivvers, Isaac; Filippenko, Alexei V; Li, Weidong; Smith, Nathan

    2016-01-01

    In Paper I of this series, we showed that the ratio between stripped-envelope supernova (SE SN) and Type II SN rates reveals a significant SE SN deficiency in galaxies with stellar masses $\\lesssim 10^{10}~{\\rm M}_\\odot$. Here, we test this result by splitting the volume-limited subsample of the Lick Observatory Supernova Search (LOSS) SN sample into low- and high-mass galaxies and comparing the relative rates of various SN types found in them. The LOSS volume-limited sample contains 180 SNe and SN impostors and is complete for SNe Ia out to 80 Mpc and core-collapse SNe out to 60 Mpc. All of these transients were recently reclassified by us in Shivvers et al. (in prep.) We find that the relative rates of some types of SNe differ between low- and high-mass galaxies: SNe Ib and Ic are underrepresented by a factor of ~3 in low-mass galaxies. These galaxies also contain the only examples of SN 1987A-like SNe in the sample and host ~9 times as many SN impostors. Normal SNe Ia are ~30% more common in low-mass galax...

  19. Clustering of galaxies in a hierarchical universe - II. Evolution to high redshift

    Science.gov (United States)

    Kauffmann, Guinevere; Colberg, Jörg M.; Diaferio, Antonaldo; White, Simon D. M.

    1999-08-01

    In hierarchical cosmologies the evolution of galaxy clustering depends both on cosmological quantities such as Omega, Lambda and P(k), which determine how collapsed structures - dark matter haloes - form and evolve, and on the physical processes - cooling, star formation, radiative and hydrodynamic feedback - which drive the formation of galaxies within these merging haloes. In this paper we combine dissipationless cosmological N-body simulations and semi-analytic models of galaxy formation in order to study how these two aspects interact. We focus on the differences in clustering predicted for galaxies of differing luminosity, colour, morphology and star formation rate, and on what these differences can teach us about the galaxy formation process. We show that a `dip' in the amplitude of galaxy correlations between z=0 and z=1 can be an important diagnostic. Such a dip occurs in low-density CDM models, because structure forms early, and dark matter haloes of mass ~10^12M_solar, containing galaxies with luminosities ~L_*, are unbiased tracers of the dark matter over this redshift range; their clustering amplitude then evolves similarly to that of the dark matter. At higher redshifts, bright galaxies become strongly biased and the clustering amplitude increases again. In high density models, structure forms late, and bias evolves much more rapidly. As a result, the clustering amplitude of L_* galaxies remains constant from z=0 to z=1. The strength of these effects is sensitive to sample selection. The dip becomes weaker for galaxies with lower star formation rates, redder colours, higher luminosities and earlier morphological types. We explain why this is the case, and how it is related to the variation with redshift of the abundance and environment of the observed galaxies. We also show that the relative peculiar velocities of galaxies are biased low in our models, but that this effect is never very strong. Studies of clustering evolution as a function of galaxy

  20. Galaxy Modelling - II. Multi-Wavelength Faint Counts from a Semi-Analytic Model of Galaxy Formation

    CERN Document Server

    Devriendt, J E G

    2000-01-01

    (Abridged) This paper predicts self-consistent faint galaxy counts from the UV to the submm wavelength range. The STARDUST spectral energy distributions described in Devriendt et al. (1999) are embedded within the explicit cosmological framework of a simple semi-analytic model of galaxy formation and evolution. We build a class of models which capture the luminosity budget of the universe through faint galaxy counts and redshift distributions in the whole wavelength range spanned by our spectra. In contrast with a rather stable behaviour in the optical and even in the far-IR, the submm counts are dramatically sensitive to variations in the cosmological parameters and changes in the star formation history. Faint submm counts are more easily accommodated within an open universe with a low value of $\\Omega_0$, or a flat universe with a non-zero cosmological constant. This study illustrates the implementation of multi-wavelength spectra into a semi-analytic model. In spite of its simplicity, it already provides f...

  1. Hydra II: a faint and compact Milky Way dwarf galaxy found in the Survey of the Magellanic Stellar History

    CERN Document Server

    Martin, Nicolas F; Besla, Gurtina; Olsen, Knut; Walker, Alistair R; Vivas, A Katherina; Gruendl, Robert A; Muñoz, Ricardo R; Blum, Robert D; Saha, Abhijit; Conn, Blair C; Bell, Eric F; Chu, You-Hua; Cioni, Maria-Rosa L; de Boer, Thomas J L; Gallart, Carme; Jin, Shoko; Kunder, Andrea; Majewski, Steven R; Martinez-Delgado, David; Monachesi, Antonela; Monelli, Matteo; Monteagudo, Lara; Noël, Noelia E D; Olszewski, Edward W; Stringfellow, Guy S; van der Marel, Roeland P; Zaritsky, Denis

    2015-01-01

    We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the MAgellanic Stellar History (SMASH) conducted with the Dark Energy Camera on the Blanco 4m Telescope. The new satellite is compact (r_h = 68 +/- 11 pc) and faint (M_V = -4.8 +/- 0.3), but well within the realm of dwarf galaxies. The stellar distribution of HydraII in the color-magnitude diagram is well-described by a metal-poor ([Fe/H] = -2.2) and old (13 Gyr) isochrone and shows a distinct blue horizontal branch, some possible red clump stars, and faint stars that are suggestive of blue stragglers. At a heliocentric distance of 134 +/- 10 kpc, Hydra II is located in a region of the Galactic halo that models have suggested may host material from the leading arm of the Magellanic Stream. A comparison with N-body simulations hints that the new dwarf galaxy could be or could have been a satellite of the Magellanic Clouds.

  2. The Buried Starburst in the Interacting Galaxy II Zw 096 as Revealed by the Spitzer Space Telescope

    CERN Document Server

    Inami, Hanae; Surace, J A; Mazzarella, J M; Evans, A S; Sanders, D B; Howell, J H; Petric, A; Vavilkin, T; Iwasawa, K; Haan, S; Murphy, E J; Stierwalt, S; Appleton, P N; Barnes, J E; Bothun, G; Bridge, C R; Chan, B; Charmandaris, V; Frayer, D T; Kewley, L J; Kim, D C; Lord, S; Madore, B F; Marshall, J A; Matsuhara, H; Melbourne, J E; Rich, J; Schulz, B; Spoon, H W W; Sturm, E; U, V; Veilleux, S; Xu, K

    2010-01-01

    An analysis of data from the Spitzer Space Telescope, Hubble Space Telescope, Chandra X-ray Observatory, and AKARI Infrared Astronomy Satellite is presented for the z=0.036 merging galaxy system II Zw 096 (CGCG 448-020). Because II Zw 096 has an infrared luminosity of log(L_IR/L_sun) = 11.94, it is classified as a Luminous Infrared Galaxy (LIRG), and was observed as part of the Great Observatories All-sky LIRG Survey (GOALS). The Spitzer data suggest that 80% of the total infrared luminosity comes from an extremely compact, red source not associated with the nuclei of the merging galaxies. The Spitzer mid-infrared spectra indicate no high-ionization lines from a buried active galactic nucleus in this source. The strong detection of the 3.3 micron and 6.2 micron PAH emission features in the AKARI and Spitzer spectra also implies that the energy source of II Zw 096 is a starburst. Based on Spitzer infrared imaging and AKARI near-infrared spectroscopy, the star formation rate is estimated to be 120 M_sun/yr and ...

  3. G359.87+0.18 An FR II Radio Galaxy 15 Arcminutes from Sgr $A^{*}$

    CERN Document Server

    Lazio, T J W; Goss, W M; Kassim, N E; Cordes, J M; Kassim, Namir E.; Cordes, James M.

    1999-01-01

    G359.87+0.18 is an enigmatic object located 15' from Sgr A*. It has been variously classified as an extragalactic source, Galactic jet source, and young supernova remnant. We present new observations of G359.87+0.18 between 0.33 and 15 GHz and use these to argue that this source is an Faranoff-Riley II radio galaxy. We are able to place a crude limit on its redshift of z > 0.1. The source has a spectral index \\alpha ~ 2. The scattering diameters of Sgr A* and several nearby OH masers (~ 1" at 1 GHz) indicate that a region of enhanced scattering is along the line of sight to the Galactic center. If the region covers the Galactic center uniformly, the implied diameter for a background source is at least 600" at 0.33 GHz, in contrast with the observed 20" diameter of G359.87+0.18. Using the scattering diameter of a nearby OH maser OH 359.762+0.120 and the widths of two, nearby, non-thermal threads, G0.08+0.15 and G359.79+0.17, we show that a uniform scattering region should cover G359.87+0.18. We therefore concl...

  4. Chemical Diversity in the Ultra-faint Dwarf Galaxy Tucana II

    CERN Document Server

    Ji, Alexander P; Ezzeddine, Rana; Casey, Andrew R

    2016-01-01

    We present the first detailed chemical abundance study of the ultra-faint dwarf galaxy Tucana II based on high-resolution Magellan/MIKE spectra of four red giant stars. The metallicity of these stars ranges from [Fe/H] = -3.2 to -2.6, and all stars are low in neutron-capture abundances ([Sr/Fe] and [Ba/Fe] < -1). However, a number of anomalous chemical signatures are present. Three stars are carbon-enhanced, including the most metal-rich star. This star ([Fe/H]=-2.6) shows [Na,$\\alpha$,Sc/Fe] < 0, suggesting an extended star formation history with contributions from AGB stars and Type Ia supernovae. The other carbon-enhanced stars have [Fe/H] < -3 and may be consistent with enrichment by faint supernovae, if such supernovae can produce neutron-capture elements. A fourth star with [Fe/H] = -3 is carbon-normal, and exhibits distinct light element abundance ratios from the carbon-enhanced stars. The carbon-normal star implies that at least two distinct nucleosynthesis sources, both possibly associated w...

  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. Study of the Sextans dwarf spheroidal galaxy from the DART CaII triplet survey

    CERN Document Server

    Battaglia, G; Helmi, A; Irwin, M; Parisi, P; Hill, V; Jablonka, P

    2010-01-01

    We use VLT/FLAMES intermediate resolution (R~6500) spectra of individual red giant branch stars in the near-infrared CaII triplet (CaT) region to investigate the wide-area metallicity properties and internal kinematics of the Sextans dwarf spheroidal galaxy (dSph). Our final sample consists of 174 probable members of Sextans with accurate line-of-sight velocities (+- 2 km/s) and CaT [Fe/H] measurements (+- 0.2 dex). We use the MgI line at 8806.8 \\AA\\, as an empirical discriminator for distinguishing between probable members of the dSph (giant stars) and probable Galactic contaminants (dwarf stars). Sextans shows a similar chemo-dynamical behaviour to other Milky Way dSphs, with its central regions being more metal rich than the outer parts and with the more metal-rich stars displaying colder kinematics than the more metal-poor stars. Hints of a velocity gradient are found along the projected major axis and along an axis at P.A.=191 deg, however a larger and more spatially extended sample may be necessary to p...

  7. Galaxy Groups in the SDSS DR4: II. halo occupation statistics

    CERN Document Server

    Yang, Xiaohu; Bosch, Frank C van den

    2007-01-01

    We investigate various halo occupation statistics using a large galaxy group catalogue constructed from the SDSS DR4 with an adaptive halo-based group finder. The conditional luminosity function (CLF) is measured separately for all, red and blue galaxies, as well as in terms of central and satellite galaxies. The CLFs for central and satellite galaxies can be well modelled with a log-normal distribution and a modified Schechter form, respectively. About 85% of the central galaxies and about 80% of the satellite galaxies in halos with masses $M_h\\ga 10^{14}\\msunh$ are red galaxies. These numbers decrease to 50% and 40%, respectively, in halos with $M_h \\sim 10^{12}\\msunh$. For halos of a given mass, the distribution of the luminosities of central galaxies, $L_c$, has a dispersion of about 0.15 dex. The mean luminosity (stellar mass) of the central galaxies scales with halo mass as $L_c\\propto M_h^{0.17}$ ($M_{*,c}\\propto M_h^{0.22}$) for halos with masses $M\\gg 10^{12.5}\\msunh$, and both relations are signific...

  8. Galactic winds with MUSE: A direct detection of Fe II* emission from a z = 1.29 galaxy

    Science.gov (United States)

    Finley, Hayley; Bouché, Nicolas; Contini, Thierry; Epinat, Benoît; Bacon, Roland; Brinchmann, Jarle; Cantalupo, Sebastiano; Erroz-Ferrer, Santiago; Marino, Raffaella Anna; Maseda, Michael; Richard, Johan; Schroetter, Ilane; Verhamme, Anne; Weilbacher, Peter M.; Wendt, Martin; Wisotzki, Lutz

    2017-09-01

    Emission signatures from galactic winds provide an opportunity to directly map the outflowing gas, but this is traditionally challenging because of the low surface brightness. Using very deep observations (27 h) of the Hubble Deep Field South with the Multi Unit Spectroscopic Explorer (MUSE) instrument, we identify signatures of an outflow in both emission and absorption from a spatially resolved galaxy at z = 1.29 with a stellar mass M⋆ = 8 × 109M⊙, star formation rate SFR = 77+40-25 M⊙ yr-1, and star formation rate surface brightness ΣSFR = 1.6M⊙ kpc-2 within the [Oii] λλ3727,3729 half-light radius R1/2, [OII] = 2.76 ± 0.17 kpc. From a component of the strong resonant Mg II and Fe II absorptions at -350 km s-1, we infer a mass outflow rate that is comparable to the star formation rate. We detect non-resonant Fe II* emission, at λ2365, λ2396, λ2612, and λ2626, at 1.2-2.4-1.5-2.7 × 10-18 erg s-1 cm-2 respectively. The flux ratios are consistent with the expectations for optically thick gas. By combining the four non-resonant Fe II* emission lines, we spatially map the Fe II* emission from an individual galaxy for the first time. The Fe II* emission has an elliptical morphology that is roughly aligned with the galaxy minor kinematic axis, and its integrated half-light radius, R1/2, Fe II ∗ =4.1 ± 0.4 kpc, is 70% larger than the stellar continuum (R1/2,⋆ ≃2.34 ± 0.17) or the [Oii] nebular line. Moreover, the Fe II* emission shows a blue wing extending up to -400 km s-1, which is more pronounced along the galaxy minor kinematic axis and reveals a C-shaped pattern in a p-v diagram along that axis. These features are consistent with a bi-conical outflow. Based on observations of the Hubble Deep Field South made with ESO telescopes at the La Silla Paranal Observatory under program ID 60.A-9100(C). Advanced data products are available at http://muse-vlt.eu/ science

  9. VizieR Online Data Catalog: Dwarf galaxies surface brightness profiles. II. (Herrmann+, 2016)

    Science.gov (United States)

    Herrmann, K. A.; Hunter, D. A.; Elmegreen, B. G.

    2016-07-01

    Our galaxy sample (see Table1) is derived from the survey of nearby (>30Mpc) late-type galaxies conducted by Hunter & Elmegreen 2006 (cat. J/ApJS/162/49). The full survey includes 94 dwarf Irregulars (dIms), 26 Blue Compact Dwarfs (BCDs), and 20 Magellanic-type spirals (Sms). The 141 dwarf sample presented in the first paper of the present series (Paper I; Herrmann et al. 2013, Cat. J/AJ/146/104) contains one fewer Sm galaxy and two additional dIm systems than the original survey. A multi-wavelength data set has been assembled for these galaxies. The data include Hα images (129 galaxies with detections) to trace star formation over the past 10Myr (Hunter & Elmegreen 2004, Cat. J/AJ/128/2170) and satellite UV images (61 galaxies observed) obtained with the Galaxy Evolution Explorer (GALEX) to trace star formation over the past ~200Myr. The GALEX data include images from two passbands with effective wavelengths of 1516Å (FUV) and 2267Å (NUV) and resolutions of 4'' and 5.6'', respectively. Three of the galaxies in our sample with NUV data do not have FUV data. To trace older stars we have UBV images, which are sensitive to stars formed over the past 1Gyr for on-going star formation, and images in at least one band of JHK for 40 galaxies in the sample, which integrates the star formation over the galaxy's lifetime. Note that nine dwarfs are missing UB data and three more are missing U-band data. In addition we made use of 3.6μm images (39 galaxies) obtained with the Infrared Array Camera (IRAC) in the Spitzer archives also to probe old stars. (3 data files).

  10. Origin and Properties of Strong Mg II Quasar Absorption Line Systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Strong Mg II quasar absorption line systems provide us with a useful tool to understand the gas that plays an important role in galaxy formation. In this paper, placing the theories of galaxy formation in a cosmological context, we present semi-analytic models and Monte-Carlo simulations for strong Mg II absorbers produced in gaseous galactic haloes and/or galaxy discs. We investigate the redshift path density for the MgII absorption lines and the properties of galaxy/absorber pairs, in particular the anti-correlation between the equivalent width of Mg II absorption line and the projected galaxy-to-sightline distance. The simulated result of the mean redshift path density of strong Mg II systems is consistent with the observational result. The fraction of strong Mg II systems arising from galaxy disks is predicted to be ~ 10% of the total. There exists an anti-correlation between the absorption line equivalent and the projected distance of sightline to galaxy center and galaxy luminosity. We determined that the mean absorbing radius Rabs ≈ 29h-1 kpc(LB/LB*)0.35. After taking selection effects into consideration, this becomes Rabs ≈ 38 h-1 kpc(LB/LB*)0.18, which is in good agreement with the observational result. This shows the importance of considering selection effects when comparing models with observations.

  11. ALMA Reveals Strong [C II] Emission in a Galaxy Embedded in a Giant Lyα Blob at z = 3.1

    Science.gov (United States)

    Umehata, Hideki; Matsuda, Yuichi; Tamura, Yoichi; Kohno, Kotaro; Smail, Ian; Ivison, R. J.; Steidel, Charles C.; Chapman, Scott C.; Geach, James E.; Hayes, Matthew; Nagao, Tohru; Ao, Yiping; Kawabe, Ryohei; Yun, Min S.; Hatsukade, Bunyo; Kubo, Mariko; Kato, Yuta; Saito, Tomoki; Ikarashi, Soh; Nakanishi, Kouichiro; Lee, Minju; Izumi, Takuma; Mori, Masao; Ouchi, Masami

    2017-01-01

    We report the result from observations conducted with the Atacama Large Millimeter/submillimeter Array (ALMA) to detect [C ii] 158 μm fine structure line emission from galaxies embedded in one of the most spectacular Lyα blobs (LABs) at z = 3.1, SSA22-LAB1. Of three dusty star-forming galaxies previously discovered by ALMA 860 μm dust continuum survey toward SSA22-LAB1, we detected the [C ii] line from one, LAB1-ALMA3 at z = 3.0993 ± 0.0004. No line emission was detected, associated with the other ALMA continuum sources or from three rest-frame UV/optical selected zspec ≃ 3.1 galaxies within the field of view. For LAB1-ALMA3, we find relatively bright [C ii] emission compared to the infrared luminosity (L[C ii]/LIR ≈ 0.01) and an extremely high [C ii] 158 μm and [N ii] 205 μm emission line ratio (L[C ii]/L[N ii] > 55). The relatively strong [C ii] emission may be caused by abundant photodissociation regions and sub-solar metallicity, or by shock heating. The origin of the unusually strong [C ii] emission could be causally related to the location within the giant LAB, although the relationship between extended Lyα emission and interstellar medium conditions of associated galaxies is yet to be understand.

  12. GALAXY CLUSTERS IN THE LINE OF SIGHT TO BACKGROUND QUASARS. III. MULTI-OBJECT SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, H.; Barrientos, L. F.; Padilla, N.; Lacerna, I. [Instituto de Astrofisica, Pontificia Universidad Catolica de Chile, Avenida Vicuna Mackenna 4860, Santiago (Chile); Lopez, S.; Lira, P.; Maureira, M. J. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Gilbank, D. G. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935 (South Africa); Ellingson, E. [Center for Astrophysics and Space Astronomy, University of Colorado at Boulder, Campus Box 389, Boulder, CO 80309-0389 (United States); Gladders, M. D. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Yee, H. K. C., E-mail: barrientos@astro.puc.cl [Department of Astronomy and Astrophysics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 3H8 (Canada)

    2013-09-01

    We present Gemini/GMOS-S multi-object spectroscopy of 31 galaxy cluster candidates at redshifts between 0.2 and 1.0 and centered on QSO sight lines taken from Lopez et al. The targets were selected based on the presence of an intervening Mg II absorption system at a similar redshift to that of a galaxy cluster candidate lying at a projected distance <2 h{sub 71}{sup -1} Mpc from the QSO sight line (a {sup p}hotometric hit{sup )}. The absorption systems span rest-frame equivalent widths between 0.015 and 2.028 A. Our aim was three-fold: (1) to identify the absorbing galaxies and determine their impact parameters, (2) to confirm the galaxy cluster candidates in the vicinity of each quasar sightline, and (3) to determine whether the absorbing galaxies reside in galaxy clusters. In this way, we are able to characterize the absorption systems associated with cluster members. Our main findings are as follows. (1) We identified 10 out of 24 absorbing galaxies with redshifts between 0.2509 {<=} z{sub gal} {<=} 1.0955, up to an impact parameter of 142 h{sub 71}{sup -1} kpc and a maximum velocity difference of 280 km s{sup -1}. (2) We spectroscopically confirmed 20 out of 31 cluster/group candidates, with most of the confirmed clusters/groups at z < 0.7. This relatively low efficiency results from the fact that we centered our observations on the QSO location, and thus occasionally some of the cluster centers were outside the instrument field of view. (3) Following from the results above, we spectroscopically confirmed of 10 out of 14 photometric hits within {approx}650 km s{sup -1} from galaxy clusters/groups, in addition to two new ones related to galaxy group environments. These numbers imply efficiencies of 71% in finding such systems with MOS spectroscopy. This is a remarkable result since we defined a photometric hit as those cluster-absorber pairs having a redshift difference {Delta}z = 0.1. The general population of our confirmed absorbing galaxies have luminosities

  13. On the population of remnant Fanaroff-Riley type II radio galaxies and implications for radio source dynamics

    Science.gov (United States)

    Godfrey, L. E. H.; Morganti, R.; Brienza, M.

    2017-10-01

    The purpose of this work is two-fold: (1) to quantify the occurrence of ultrasteep spectrum remnant Fanaroff-Riley type II (FRII) radio galaxies in a 74 MHz flux-limited sample, and (2) perform Monte Carlo simulations of the population of active and remnant FRII radio galaxies to confront models of remnant lobe evolution, and to provide guidance for further investigation of remnant radio galaxies. We find that fewer than 2 per cent of FRII radio galaxies with S74 MHz > 1.5 Jy are candidate ultrasteep spectrum remnants, where we define ultrasteep spectrum as α _74 MHz^1400 MHz > 1.2. Our Monte Carlo simulations demonstrate that models involving Sedov-like expansion in the remnant phase, resulting in rapid adiabatic energy losses, are consistent with this upper limit, and predict the existence of nearly twice as many remnants with normal (not ultrasteep) spectra in the observed frequency range as there are ultrasteep spectrum remnants. This model also predicts an ultrasteep remnant fraction approaching 10 per cent at redshifts z population.

  14. Photometric H alpha and [O II] Luminosity Function of SDF and SXDF Galaxies: Implications for Future Baryon Oscillation Surveys

    CERN Document Server

    Sumiyoshi, Masanao; Oshige, Shunsuke; Glazebrook, Karl; Akiyama, Masayuki; Morokuma, Tomoki; Motohara, Kentaro; Shimasaku, Kazuhiro; Hayashi, Masao; Yoshida, Makiko; Kashikawa, Nobunari; Kodama, Tadayuki

    2009-01-01

    Efficient selection of emission line galaxies at z > 1 by photometric information in wide field surveys is one of the keys for future spectroscopic surveys to constrain dark energy using the baryon acoustic oscillation (BAO) signature. Here we estimate the H alpha and [O II] line luminosity functions of galaxies at z = 0.5-1.7 using a novel approach where multi-wavelength imaging data is used to jointly estimate both photometric redshifts and star-formation rates. These photometric estimates of line luminosities at high-redshift use the large data sets of the Subaru Deep Field and Subaru XMM-Newton Deep Field (covering \\sim 1 deg^2) and are calibrated with the spectroscopic data of the local Sloan Digital Sky Survey galaxies. The derived luminosity functions (especially H alpha) are in reasonable agreement with the past estimates based on spectroscopic or narrow-band-filter surveys. This dataset is useful for examining the photometric selection of target galaxies for BAO surveys because of the large cosmologi...

  15. Theoretical determination of HI vertical scale heights in the dwarf galaxies: DDO 154, HoII, IC2574 & NGC2366

    CERN Document Server

    Banerjee, Arunima; Brinks, Elias; Bagetakos, Ioannis

    2011-01-01

    In this paper, we model dwarf galaxies as a two-component system of gravitationally coupled stars and atomic hydrogen gas in the external force field of a pseudo-isothermal dark matter halo, and numerically obtain the radial distribution of {H\\,{\\sc i}} vertical scale heights. This is done for a group of four dwarf galaxies (DDO\\,154, Ho\\,II, IC\\,2574 and NGC\\,2366) for which most necessary input parameters are available from observations. The formulation of the equations takes into account the rising rotation curves generally observed in dwarf galaxies. The inclusion of self-gravity of the gas into the model at par with that of the stars results in scale heights that are smaller than what was obtained by previous authors. This is important as the gas scale height is often used for deriving other physical quantities. The inclusion of gas self-gravity is particularly relevant in the case of dwarf galaxies where the gas cannot be considered a minor perturbation to the mass distribution of the stars. We find tha...

  16. Dark influences II. Gas and star formation in minor mergers of dwarf galaxies with dark satellites

    NARCIS (Netherlands)

    Starkenburg, T. K.; Helmi, A.; Sales, L. V.

    2016-01-01

    Context. It has been proposed that mergers induce starbursts and lead to important morphological changes in galaxies. Most studies so far have focused on large galaxies, but dwarfs might also experience such events, since the halo mass function is scale-free in the concordance cosmological model.

  17. Group, field and isolated early-type galaxies II. Global trends from nuclear data

    CERN Document Server

    Denicolo, G; Terlevich, E; Forbes, D A; Terlevich, A I; Denicolo, Glenda; Terlevich, Roberto; Terlevich, Elena; Forbes, Duncan A.; Terlevich, Alejandro

    2004-01-01

    We have derived ages, metallicities and enhanced-element ratios [alpha/Fe] for a sample of 83 early-type galaxies essentially in groups, the field or isolated objects. The stellar population properties derived for each galaxy corresponds to the nuclear r_e/8 aperture extraction. The median age found for Es is 5.8 +- 0.6 Gyr and the average metallicity is +0.37 +- 0.03 dex. For S0s, the median age is 3.0 +- 0.6 Gyr and [Z/H] = 0.53 +- 0.04 dex. We compare the distribution of our galaxies in the Hbeta-[MgFe] diagram with Fornax galaxies. Our elliptical galaxies are 3-4 Gyr younger than Es in the Fornax cluster. We find that the galaxies lie in a plane defined by [Z/H] = 0.99 log sigma_0 - 0.46 log Age - 1.60. More massive (larger sigma_0) and older galaxies present, on average, large [alpha/Fe] values, and therefore, must have undergone shorter star-formation timescales. Comparing group against field/isolated galaxies, it is not clear that environment plays an important role in determining their stellar populat...

  18. High-lying OH absorption, [C II] deficits, and extreme $L_{\\mathrm{FIR}}/M_{\\mathrm{H2}}$ ratios in galaxies

    CERN Document Server

    González-Alfonso, E; Sturm, E; Graciá-Carpio, J; Veilleux, S; Meléndez, M; Lutz, D; Poglitsch, A; Aalto, S; Falstad, N; Spoon, H W W; Farrah, D; Blasco, A; Henkel, C; Contursi, A; Verma, A; Spaans, M; Smith, H A; Ashby, M L N; Hailey-Dunsheath, S; Garc\\'\\ia-Burillo, S; Mart\\'\\in-Pintado, J; van der Werf, P; Meijerink, R; Genzel, R

    2014-01-01

    Herschel/PACS observations of 29 local (Ultra-)Luminous Infrared Galaxies, including both starburst and AGN-dominated sources as diagnosed in the mid-infrared/optical, show that the equivalent width of the absorbing OH 65 um Pi_{3/2} J=9/2-7/2 line (W_{eq}(OH65)) with lower level energy E_{low}~300 K, is anticorrelated with the [C ii]158 um line to far-infrared luminosity ratio, and correlated with the far-infrared luminosity per unit gas mass and with the 60-to-100 um far-infrared color. While all sources are in the active L_{IR}/M_{H2}>50 Lsun/Msun mode as derived from previous CO line studies, the OH65 absorption shows a bimodal distribution with a discontinuity at L_{FIR}/M_{H2}~100 Lsun/Msun. In the most buried sources, OH65 probes material partially responsible for the silicate 9.7 um absorption. Combined with observations of the OH 71 um Pi_{1/2} J=7/2-5/2 doublet (E_{low}~415 K), radiative transfer models characterized by the equivalent dust temperature, Tdust, and the continuum optical depth at 100 u...

  19. A Measurement of the Rate of Type Ia Supernovae in Galaxy Clusters from the SDSS-II Supernova Survey

    CERN Document Server

    Dilday, Benjamin; Becker, Andrew; Bender, Ralf; Castander, Francisco; Cinabro, David; Frieman, Joshua A; Galbany, Lluís; Garnavich, Peter; Goobar, Ariel; Hopp, Ulrich; Ihara, Yutaka; Jha, Saurabh W; Kessler, Richard; Lampeitl, Hubert; Marriner, John; Miquel, Ramon; Mollá, Mercedes; Nichol, Robert C; Nordin, Jakob; Riess, Adam G; Sako, Masao; Schneider, Donald P; Smith, Mathew; Sollerman, Jesper; Wheeler, J Craig; Östman, Linda; Bizyaev, Dmitry; Brewington, Howard; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Dan; Pan, Kaike; Simmons, Audrey; Snedden, Stephanie

    2010-01-01

    ABRIDGED We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z <0.17 and 27 SN events in 492 maxBCG clusters at 0.1 < z < 0.3$. We find values for the cluster SN Ia rate of $({0.37}^{+0.17+0.01}_{-0.12-0.01}) \\mathrm{SNu}r h^{2}$ and $({0.55}^{+0.13+0.02}_{-0.11-0.01}) \\mathrm{SNu}r h^{2}$ ($\\mathrm{SNu}x = 10^{-12} L_{x\\sun}^{-1} \\mathrm{yr}^{-1}$) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be $({0.31}^{+0.18+0.01}_{-0.12-0.01}) \\mathrm{SNu}r h^{2}$ and $({0.49}^{+0.15+0.02}_{-0.11-0.01})$ $\\mathrm{SNu}r h^{2}$ in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be $({2.04}^{+1.99+0.07}_{-1.11-0.04}) \\mathrm{SNu}r h^{2}$ and $({0.36}^{+0.84+0.01}_...

  20. Integrated Properties of Nearby Seyfert Galaxies Measured by 2-D Spectroscopy

    Science.gov (United States)

    Xia, Junjie; Malkan, Matthew Arnold

    2017-01-01

    We present our measurements of mosaicing long-slit spectra of 12 nearby Seyfert galaxies. We obtained these data cubes at ~6‧‧ spatial resolution using the Kast double spectrograph on the 3-m Shane telescope of Lick Observatory. We have measured the integrated emission lines of [O III], Hβ, Hα, [N II], and [S II]. We compare the relative strength of these lines from the galaxy nucleus with the total emission from the entire galaxy. In classification line ratio diagrams (BPT), the individual galaxy moves from the Seyfert region to the composite/star-forming locus as the effective absorbing aperture grows. This trend means that Seyfert galaxies observed at higher redshifts will become increasingly misclassified. We use our sample to quantify this systematic trend. We also estimate the rates of star formation in the host galaxies based on the emission lines.

  1. HI Content and Optical Properties of Field Galaxies from the ALFALFA Survey. II. Multivariate Analysis of a Galaxy Sample in Low Density Environments

    CERN Document Server

    Toribio, M C; Giovanelli, R; Haynes, M P; Martin, A

    2011-01-01

    This is the second paper of two reporting results from a study of the HI content and stellar properties of nearby galaxies detected by the Arecibo Legacy Fast ALFA blind 21-cm line survey and the Sloan Digital Sky Survey in a 2160 deg^2 region covered by both surveys. We apply strategies of multivariate data analysis to a complete HI flux-limited subset of 1624 objects extracted from the control sample of HI emitters assembled by Toribio et al. (2011a) in order to: i) investigate the correlation structure of the space defined by an extensive set of observables describing gas-rich systems; ii) identify the intrinsic parameters that best define their HI content; and iii) explore the scaling relations arising from the joint distributions of the quantities most strongly correlated with the HI mass. The principal component analysis performed over a set of five galaxy properties reveals that they are strongly interrelated, supporting previous claims that nearby HI emitters show a high degree of correlation. The bes...

  2. Ultra-Flat Galaxies Selected from RFGC Catalog. II. Orbital Estimates of Halo Masses

    CERN Document Server

    Karachentsev, I D; Kudrya, Yu N

    2016-01-01

    We used the Revised Flat Galaxy Catalog (RFGC) to select 817 ultra-flat (UF) edge-on disk galaxies with blue and red apparent axial ratios of $(a/b)_B > 10.0$ and $(a/b)_R > 8.5$. The sample covering the whole sky, except the Milky Way zone, contains 490 UF galaxies with measured radial velocities. Our inspection of the neighboring galaxies around them revealed only 30 companions with radial velocity difference of $\\mid\\Delta V\\mid<500$ km s$^{-1}$ inside the projected separation of $R_p < 250$ kpc. Wherein, the wider area around the UF galaxy within $R_p < 750$ kpc contains no other neighbors brighter than the UF galaxy itself in the same velocity span. The resulting sample galaxies mostly belong to the morphological types Sc, Scd, Sd. They have a moderate rotation velocity curve amplitude of about $120$ km s$^{-1}$ and a moderate K-band luminosity of about $10^{10}L_{\\odot}$. The median difference of radial velocities of their companions is $87$ km s$^{-1}$, yielding the median orbital mass estimat...

  3. Supernova rates from the SUDARE VST-Omegacam search II. Rates in a galaxy sample

    CERN Document Server

    Botticella, M T; Greggio, L; Pignata, G; Della Valle, M; Grado, A; Limatola, L; Baruffolo, A; Benetti, S; Bufano, F; Capaccioli, M; Cascone, E; Covone, G; De Cicco, D; Falocco, S; Haeussler, B; Harutyunyan, V; Jarvis, M; Marchetti, L; Napolitano, N R; Paolillo, M; Pastorello, A; Radovich, M; Schipani, P; Tomasella, L; Turatto, M; Vaccari, M

    2016-01-01

    This is the second paper of a series in which we present measurements of the Supernova (SN) rates from the SUDARE survey. In this paper, we study the trend of the SN rates with the intrinsic colours, the star formation activity and the mass of the parent galaxies. We have considered a sample of about 130000 galaxies and a SN sample of about 50 events. We found that the SN Ia rate per unit mass is higher by a factor of six in the star-forming galaxies with respect to the passive galaxies. The SN Ia rate per unit mass is also higher in the less massive galaxies that are also younger. These results suggest a distribution of the delay times (DTD) less populated at long delay times than at short delays. The CC SN rate per unit mass is proportional to both the sSFR and the galaxy mass. The trends of the Type Ia and CC SN rates as a function of the sSFR and the galaxy mass that we observed from SUDARE data are in agreement with literature results at different redshifts. The expected number of SNe Ia is in agreement ...

  4. Active Galactic Nuclei from He II: a more complete census of AGN in SDSS galaxies yields a new population of low-luminosity AGN in highly star-forming galaxies

    Science.gov (United States)

    Baer, Rudolf E.; Weigel, Anna; Sartori, Lia F.; Oh, Kyuseok; Koss, Michael; Schawinski, Kevin

    2017-01-01

    In order to perform a more complete census of active galactic nuclei (AGN) in the local Universe, we investigate the use of the He II emission line diagnostic diagram by Shirazi & Brinchmann (2012) in addition to the standard methods based on other optical emission lines. The He II based diagnostics is more sensitive to AGN ionization in the presence of strong star formation than conventional line diagnostics. We survey a magnitude-limited sample of 81,192 galaxies from the Sloan Digital Sky Survey Data Release 7 at 0.02 note in particular a high He II AGN fraction in galaxies above the high-mass end of the main sequence where quenching is expected to occur. We discuss how this technique can help inform galaxy/black hole co-evolution scenarios.

  5. The PAndAS View of the Andromeda Satellite System. II. Detailed Properties of 23 M31 Dwarf Spheroidal Galaxies

    Science.gov (United States)

    Martin, Nicolas F.; Ibata, Rodrigo A.; Lewis, Geraint F.; McConnachie, Alan; Babul, Arif; Bate, Nicholas F.; Bernard, Edouard; Chapman, Scott C.; Collins, Michelle M. L.; Conn, Anthony R.; Crnojević, Denija; Fardal, Mark A.; Ferguson, Annette M. N.; Irwin, Michael; Mackey, A. Dougal; McMonigal, Brendan; Navarro, Julio F.; Rich, R. Michael

    2016-12-01

    We present a comprehensive analysis of the structural properties and luminosities of the 23 dwarf spheroidal galaxies that fall within the footprint of the Pan-Andromeda Archaeological Survey (PAndAS). These dwarf galaxies represent the large majority of Andromeda’s known satellite dwarf galaxies and cover a wide range in luminosity (-11.6≲ {M}V≲ -5.8 or {10}4.2≲ L≲ {10}6.5 {L}⊙ ) and surface brightness (25.1≲ {μ }0≲ 29.3 mag arcsec-2). We confirm most previous measurements, but we find And XIX to be significantly larger than before ({r}h={3065}-935+1065 {pc}, {M}V=-{10.1}-0.4+0.8) and cannot derive parameters for And XXVII as it is likely not a bound stellar system. We also significantly revise downward the luminosities of And XV and And XVI, which are now {M}V˜ -7.5 or L˜ {10}5 {L}⊙ . Finally, we provide the first detailed analysis of Cas II/And XXX, a fairly faint system ({M}V=-{8.0}-0.3+0.4) of typical size ({r}h=270+/- 50 {pc}), located in close proximity to the two bright elliptical dwarf galaxies NGC 147 and NGC 185. Combined with the set of homogeneous distances published in an earlier contribution, our analysis dutifully tracks all relevant sources of uncertainty in the determination of the properties of the dwarf galaxies from the PAndAS photometric catalog. We further publish the posterior probability distribution functions of all the parameters we fit for in the form of MCMC chains available online; these inputs should be used in any analysis that aims to remain truthful to the data and properly account for covariance between parameters.

  6. Cosmological galaxy evolution with superbubble feedback - II. The limits of supernovae

    Science.gov (United States)

    Keller, B. W.; Wadsley, J.; Couchman, H. M. P.

    2016-12-01

    We explore when supernovae can (and cannot) regulate the star formation and bulge growth in galaxies based on a sample of 18 simulated galaxies. The simulations are the first to model feedback superbubbles including evaporation and conduction. These processes determine the mass loadings and wind speeds of galactic outflows. We show that for galaxies with virial masses >1012 M⊙, supernovae alone cannot prevent excessive star formation. This occurs due to a shutdown of galactic winds, with wind mass loadings falling from η ˜ 10 to η loaded outflows regulate star formation on galactic scales. This implies that non-supernova feedback mechanisms must become dominant for galaxies with stellar masses greater than ˜4 × 1010 M⊙. The runaway growth of the central stellar bulge, strongly linked to black hole growth, suggests that feedback from active galactic nuclei is the likely mechanism. Below this mass, supernovae alone are able to produce a realistic stellar mass fraction, star formation history and disc morphology.

  7. Characterizing Ultraviolet and Infrared Observational Properties for Galaxies. II. Features of Attenuation Law

    CERN Document Server

    Mao, Ye-Wei; Lin, Lin

    2014-01-01

    Variations in attenuation law have a significant impact on observed spectral energy distributions for galaxies. As one important observational property for galaxies at ultraviolet and infrared wavelength bands, the correlation between infrared-to-ultraviolet luminosity ratio and ultraviolet color index (or ultraviolet spectral slope), i.e., the IRX-UV relation (or IRX-beta relation), offered a widely used recipe for correcting dust attenuation in galaxies, but the usability appears in doubt now due to considerable dispersion in this relation found by many studies. In this paper, on the basis of spectral synthesis modeling and spatially resolved measurements of four nearby spiral galaxies, we provide an interpretation of the deviation in the IRX-UV relation with variations in attenuation law. From the both theoretical and observational viewpoints, two components in attenuation curve, the linear background and the 2175 Angstrom bump, are suggested to be the parameters in addition to stellar population age (addr...

  8. Ram pressure stripping of disc galaxies orbiting in clusters. II. Galactic wakes

    CERN Document Server

    Roediger, E

    2007-01-01

    We present 3D hydrodynamical simulations of ram pressure stripping of a disc galaxy orbiting in a galaxy cluster. In this paper, we focus on the properties of the galaxies' tails of stripped gas. The galactic wakes show a flaring width, where the flaring angle depends on the gas disc's cross-section with respect to the galaxy's direction of motion. The velocity in the wakes shows a significant turbulent component of a few 100 km/s. The stripped gas is deposited in the cluster rather locally, i.e. within ~150 kpc from where it was stripped. We demonstrate that the most important quantity governing the tail density, length and gas mass distribution along the orbit is the galaxy's mass loss per orbital length. This in turn depends on the ram pressure as well as the galaxy's orbital velocity. For a sensitivity limit of ~10^19 cm^-2 in projected gas density, we find typical tail lengths of 40 kpc. Such long tails are seen even at large distances (0.5 to 1 Mpc) from the cluster centre. At this sensitivity limit, th...

  9. Cosmological Galaxy Evolution with Superbubble Feedback II: The Limits of Supernovae

    CERN Document Server

    Keller, B W; Couchman, H M P

    2016-01-01

    We explore when supernovae can (and cannot) regulate the star formation and bulge growth in galaxies based on a sample of 18 simulated galaxies. The simulations include key physics such as evaporation and conduction, neglected in prior work, and required to correctly model superbubbles resulting from stellar feedback. We show that for galaxies with virial masses $>10^{12}\\;M_\\odot$, supernovae alone cannot prevent excessive star formation. This failure occurs due to a shutdown of galactic winds, with wind mass loadings falling from $\\eta\\sim10$ to $\\eta<1$. In more massive systems, this transfer of baryons to the circumgalactic medium falters earlier on and the galaxies diverge significantly from observed galaxy scaling relations and morphologies. The decreasing efficiency is simply due to a deepening potential well preventing gas escape. This implies that non-supernova feedback mechanisms must become dominant for galaxies with stellar masses greater than $\\sim4\\times10^{10}\\;M_\\odot$. The runaway growth o...

  10. Spectroscopic Study of Blue Compact Galaxies II. Spectral Analysis and Correlations

    CERN Document Server

    Kong, X; Weiss, A; Charlot, S

    2002-01-01

    This is the second paper in a series studying the star formation rates, stellar components, metallicities, and star formation histories and evolution of a sample of blue compact galaxies. We analyzed spectral properties of 97 blue compact galaxies, obtained with the Beijing Astronomical Observatory (China) 2.16 m telescope, with spectral range 3580\\AA -- 7400\\AA. We classify the spectra according to their emission lines: 13 of the total 97 BCGs sample are non-emission line galaxies (non-ELGs); 10 have AGN-like emission (AGNs), and 74 of them are star-forming galaxies (SFGs). Emission line fluxes and equivalent widths, continuum fluxes, the 4000 \\AA Balmer break index and equivalent widths of absorption lines are measured from the spectra. We investigate the emission line trends in the integrated spectra of the star-forming galaxies in our sample, and find that: 1) The equivalent widths of emission lines are correlated with the galaxy absolute blue magnitude $M_B$; lower luminosity systems tend to have larger ...

  11. AMUSE-Field II. Nucleation of early-type galaxies in the field vs. cluster environment

    CERN Document Server

    Baldassare, Vivienne F; Miller, Brendan P; Plotkin, Richard M; Treu, Tommaso; Valluri, Monica; Woo, Jong-Hak

    2014-01-01

    The optical light profiles of nearby early type galaxies are known to exhibit a smooth transition from nuclear light deficits to nuclear light excesses with decreasing galaxy mass, with as much as 80 per cent of the galaxies with stellar masses below 10^10 Msun hosting a massive nuclear star cluster. At the same time, while all massive galaxies are thought to harbor nuclear super-massive black holes (SMBHs), observational evidence for SMBHs is slim at the low end of the mass function. Here, we explore the environmental dependence of the nucleation fraction by comparing two homogeneous samples of nearby field vs. cluster early type galaxies with uniform Hubble Space Telescope (HST) coverage. Existing Chandra X-ray Telescope data for both samples yield complementary information on low-level accretion onto nuclear SMBHs. Specifically, we report on dual-band (F475W & F850LP) Advanced Camera for Surveys (ACS) imaging data for 28 out of the 103 field early type galaxies that compose the AMUSE-Field Chandra surv...

  12. The MICE Grand Challenge Lightcone Simulation II: Halo and Galaxy catalogues

    CERN Document Server

    Crocce, M; Gaztanaga, E; Fosalba, P; Carretero, J

    2013-01-01

    This is the second in a series of three papers in which we present an end-to-end simulation from the MICE collaboration, the MICE Grand Challenge (MICE-GC) run. The N-body contains about 70 billion dark-matter particles in a (3 \\Gpc)^3 comoving volume spanning 5 orders of magnitude in dynamical range. In this paper we introduce the halo and galaxy catalogues built upon it, both in a wide (5000 sq. deg) and deep (z<1.4) light-cone and in several redshift snapshots. Friend-of-friends halos were resolved down to few 10^{11} Msun/h what allowed us to model galaxies down to faint luminosities (absolute magnitudes M_r<-18.9). We used a new hybrid Halo Occupation Distribution and Abundance Matching technique for galaxy assignment. The catalogue includes the Spectral Energy Distributions of all galaxies from which we can model multi-band photometric galaxy surveys. We describe a variety of applications for halo and galaxy clustering statistics. We discuss how mass resolution effects can bias the large scale 2-p...

  13. Supernovae and their host galaxies - II. The relative frequencies of supernovae types in spirals

    CERN Document Server

    Hakobyan, A A; Adibekyan, V Zh; Petrosian, A R; Aramyan, L S; Kunth, D; Mamon, G A; de Lapparent, V; Bertin, E; Gomes, J M; Turatto, M

    2014-01-01

    (Abridged) In this second paper of a series, we present an analysis of the relative frequencies of different supernova (SN) types in spirals with various morphologies and in barred or unbarred galaxies. We use a well-defined and homogeneous sample of host galaxies from the Sloan Digital Sky Survey (SDSS) in different stages of galaxy-galaxy interaction. We propose that the underlying mechanisms shaping the number ratios of SNe types can be interpreted within the framework of interaction-induced star formation, in addition to the known relations between morphologies and stellar populations. We find a strong trend in behaviour of the NIa/NCC ratio depending on host morphology, such that early spirals include more type Ia SNe, reflecting the change of the specific star formation rate (SFR). The NIbc/NII ratio is higher in a broad bin of early-type hosts. The NIa/NCC ratio is nearly constant when changing from normal, perturbed to interacting galaxies, then declines in merging galaxies, whereas it jumps to the hi...

  14. Probing the intra-group medium of a z = 0.28 galaxy group

    CERN Document Server

    Bielby, R; Fumagalli, M; Morris, S L; Stott, J P; Tejos, N; Cantalupo, S

    2016-01-01

    We present new MUSE observations of a galaxy group probed by a background quasar. The quasar sightline passes between multiple $z=0.28$ galaxies, whilst showing at the same redshift low ionised metal line species, including Ca II, Mg I, Mg II and Fe II. Based on the galaxy redshifts measured from the MUSE data, we estimate the galaxies to be part of a small galaxy group with a halo mass of $\\approx6\\times10^{12}$ M$_{\\odot}$. We use the MUSE data to reveal the two dimensional dynamical properties of the gas and stars in the group galaxies, and relate these to the absorber kinematics. With these data we consider four scenarios for the nature of the gas probed by the sightline absorbers: a co-rotating gas halo associated with a single galaxy within the group; outflowing material from a single group member powered by recent star-formation; and cool dense gas embedded within the intra-group medium. We find that the dynamics, alongside the galaxy impact parameters and star-formation rates, favour the latter, in wh...

  15. High Resolution STIS/HST and HIRES/Keck Spectra of Three Weak MgII Absorbers Toward PG 1634+706

    CERN Document Server

    Charlton, J C; Zonak, S G; Churchill, C W; Bond, N A; Rigby, J R

    2003-01-01

    High resolution optical (HIRES/Keck) and UV (STIS/HST) spectra, covering a large range of chemical transitions, are analyzed for three single-cloud weak MgII absorption systems along the line of sight toward the quasar PG 1634+706. Weak MgII absorption lines in quasar spectra trace metal-enriched environments that are rarely closely associated with the most luminous galaxies (>0.05L^*). The two weak MgII systems at z=0.81 and z=0.90 are constrained to have >=solar metallicity, while the metallicity of the z=0.65 system is not as well-constrained, but is consistent with >1/10th solar. These weak MgII clouds are likely to be local pockets of high metallicity in a lower metallicity environment. All three systems have two phases of gas, a higher density region that produces narrower absorption lines for low ionization transitions, such as MgII, and a lower density region that produces broader absorption lines for high ionization transitions, such as CIV. The CIV profile for one system (at z=0.81) can be fit with ...

  16. The PAndAS view of the Andromeda satellite system - II. Detailed properties of 23 M31 dwarf spheroidal galaxies

    CERN Document Server

    Martin, Nicolas F; Lewis, Geraint F; McConnachie, Alan; Babul, Arif; Bate, Nicholas F; Bernard, Edouard; Chapman, Scott C; Collins, Michelle M L; Conn, Anthony R; Crnojević, Denija; Fardal, Mark A; Ferguson, Annette M N; Irwin, Michael; Mackey, A Dougal; McMonigal, Brendan; Navarro, Julio F; Rich, R Michael

    2016-01-01

    We present a comprehensive analysis of the structural properties and luminosities of the 23 dwarf spheroidal galaxies that fall within the footprint of the Pan-Andromeda Archaeological Survey (PAndAS). These dwarf galaxies represent the large majority of Andromeda's known satellite dwarf galaxies and cover a wide range in luminosity ($-11.6II/And XXX, a fairly faint system ($M_V=-8.0^{+0.4}_{-0.3}$) of typical size ($r_h=270\\pm50$ pc), located in close proximity to the t...

  17. SDSS-II Supernova Survey: An Analysis of the Largest Sample of Type Ia Supernovae and Correlations with Host-Galaxy Spectral Properties

    CERN Document Server

    Wolf, Rachel C; Gupta, Ravi R; Sako, Masao; Fischer, John A; Kessler, Rick; Jha, Saurabh W; March, Marisa C; Scolnic, Daniel M; Fischer, Johanna-Laina; Campbell, Heather; Nichol, Robert C; Olmstead, Matthew D; Richmond, Michael; Schneider, Donald P; Smith, Mathew

    2016-01-01

    Using the largest single-survey sample of Type Ia supernovae (SNe Ia) to date, we study the relationship between properties of SNe Ia and those of their host galaxies, focusing primarily on correlations with Hubble residuals (HR). Our sample consists of 345 photometrically-classified or spectroscopically-confirmed SNeIa discovered as part of the SDSS-II Supernova Survey (SDSS-SNS). This analysis utilizes host-galaxy spectroscopy obtained during the SDSS-I/II spectroscopic survey and from an ancillary program on the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) that obtained spectra for nearly all host galaxies of SDSS-II SN candidates. In addition, we use photometric host-galaxy properties from the SDSS-SNS data release (Sako et al. 2014) such as host stellar mass and star-formation rate. We confirm the well-known relation between HR and host-galaxy mass and find a 3.6{\\sigma} significance of a non-zero linear slope. We also recover correlations between HR and host-galaxy gas-phase metallicity and s...

  18. A Measurement of the Rate of Type Ia Supernovae in Galaxy Clusters from the SDSS-II Supernova Survey

    Energy Technology Data Exchange (ETDEWEB)

    Dilday, Benjamin; /Rutgers U., Piscataway /Chicago U. /KICP, Chicago; Bassett, Bruce; /Cape Town U., Dept. Math. /South African Astron. Observ.; Becker, Andrew; /Washington U., Seattle, Astron. Dept.; Bender, Ralf; /Munich, Tech. U. /Munich U. Observ.; Castander, Francisco; /Barcelona, IEEC; Cinabro, David; /Wayne State U.; Frieman, Joshua A.; /Chicago U. /Fermilab; Galbany, Lluis; /Barcelona, IFAE; Garnavich, Peter; /Notre Dame U.; Goobar, Ariel; /Stockholm U., OKC /Stockholm U.; Hopp, Ulrich; /Munich, Tech. U. /Munich U. Observ. /Tokyo U.

    2010-03-01

    We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z {le} 0.17 and 27 SN events in 492 maxBCG clusters at 0.1 {le} z {le} 0.3. We find values for the cluster SN Ia rate of (0.37{sub -0.12-0.01}{sup +0.17+0.01}) SNur h{sup 2} and (0.55{sub -0.11-0.01}{sup +0.13+0.02}) SNur h{sup 2} (SNux = 10{sup -12}L{sub x{circle_dot}}{sup -1} yr{sup -1}) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be (0.31{sub -0.12-0.01}{sup +0.18+0.01}) SNur h{sup 2} and (0.49{sub -0.11-0.01}{sup +0.15+0.02}) SNur h{sup 2} in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be (2.04{sub -1.11-0.04}{sup +1.99+0.07}) SNur h{sup 2} and (0.36{sub -0.30-0.01}{sup +0.84+0.01}) SNur h{sup 2} in C4 and maxBCG clusters, respectively. The ratio of the SN Ia rate in cluster early-type galaxies to that of the SN Ia rate in field early-type galaxies is 1.94{sub -0.91-0.015}{sup +1.31+0.043} and 3.02{sub -1.03-0.048}{sup +1.31+0.062}, for C4 and maxBCG clusters, respectively. The SN rate in galaxy clusters as a function of redshift, which probes the late time SN Ia delay distribution, shows only weak dependence on redshift. Combining our current measurements with previous measurements, we fit the cluster SN Ia rate data to a linear function of redshift, and find r{sub L} = [(0.49{sub -0.14}{sup +0.15}) + (0.91{sub -0.81}{sup +0.85}) x z] SNuB h{sup 2}. A comparison of the radial distribution of SNe in cluster to field early-type galaxies shows possible evidence for an enhancement of the SN rate in the cores of cluster early-type galaxies. With an observation of at most 3 hostless, intra-cluster SNe Ia, we estimate the fraction of cluster SNe that are

  19. Fanaroff-Riley I galaxies as the parent population of BL Lacertae objects. II - Optical constraints

    Energy Technology Data Exchange (ETDEWEB)

    Padovani, P.; Urry, C.M. (Space Telescope Science Institute, Baltimore, MD (USA))

    1991-02-01

    The hypothesis is investigated that BL Lacertae objects are a subset of Fanaroff-Riley (FR) I galaxies dominated by beamed emission from a relativistic jet aligned with the line of sight. It is found that FR I galaxies, although of low radio luminosity, are bright optical galaxies. If the beaming hypothesis is correct, the optical luminosity function of BL Lac objects, including the effect of the host galaxy, can be approximated by a double power law with a given differential index. New estimates of the number counts of BL Lac objects are made which constrain their local number density for L(B) greater than about 6 x 10 to the 43rd ergs/s to be in the range 110-720/cu Gpc. The corresponding ratio between the total number densities of BL Lac objects and FR I galaxies is 0.003 to 0.02. This limits the Lorentz factor of the optical emission to the range 8-20, larger than that of the X-ray emitting plasma and roughly of the same order as the radio Lorentz factor. 34 refs.

  20. Interaction effects on galaxy pairs with Gemini/GMOS- II: Oxygen abundance gradients

    CERN Document Server

    Rosa, D A; Krabbe, A C; Hagele, G F; Cardaci, M V; Pastoriza, M G; Rodrigues, I; Winge, C

    2014-01-01

    In this paper we derived oxygen abundance gradients from HII regions located in eleven galaxies in eight systems of close pairs. Long-slit spectra in the range 4400-7300A were obtained with the Gemini Multi-Object Spec- trograph at Gemini South (GMOS). Spatial profiles of oxygen abundance in the gaseous phase along galaxy disks were obtained using calibrations based on strong emission-lines (N2 and O3N2). We found oxygen gradients signifi- cantly flatter for all the studied galaxies than those in typical isolated spiral galaxies. Four objects in our sample, AM1219A, AM1256B, AM 2030A and AM2030B, show a clear break in the oxygen abundance at galactocentric radius R/R25 between 0.2 and 0.5. For AM1219A and AM1256B we found negative slopes for the inner gradients, and for AM2030B we found a positive one. In all these three cases they show a flatter behaviour to the outskirts of the galaxies. For AM2030A, we found a positive-slope outer gradient while the inner one is almost compatible with a flat behaviour. A d...

  1. Supernova rates from the SUDARE VST-Omegacam search II. Rates in a galaxy sample

    Science.gov (United States)

    Botticella, M. T.; Cappellaro, E.; Greggio, L.; Pignata, G.; Della Valle, M.; Grado, A.; Limatola, L.; Baruffolo, A.; Benetti, S.; Bufano, F.; Capaccioli, M.; Cascone, E.; Covone, G.; De Cicco, D.; Falocco, S.; Haeussler, B.; Harutyunyan, V.; Jarvis, M.; Marchetti, L.; Napolitano, N. R.; Paolillo, M.; Pastorello, A.; Radovich, M.; Schipani, P.; Tomasella, L.; Turatto, M.; Vaccari, M.

    2017-02-01

    Aims: This is the second paper of a series in which we present measurements of the supernova (SN) rates from the SUDARE survey. The aim of this survey is to constrain the core collapse (CC) and Type Ia SN progenitors by analysing the dependence of their explosion rate on the properties of the parent stellar population averaging over a population of galaxies with different ages in a cosmic volume and in a galaxy sample. In this paper, we study the trend of the SN rates with the intrinsic colours, the star formation activity and the masses of the parent galaxies. To constrain the SN progenitors we compare the observed rates with model predictions assuming four progenitor models for SNe Ia with different distribution functions of the time intervals between the formation of the progenitor and the explosion, and a mass range of 8-40 M⊙ for CC SN progenitors. Methods: We considered a galaxy sample of approximately 130 000 galaxies and a SN sample of approximately 50 events. The wealth of photometric information for our galaxy sample allows us to apply the spectral energy distribution (SED) fitting technique to estimate the intrinsic rest frame colours, the stellar mass and star formation rate (SFR) for each galaxy in the sample. The galaxies have been separated into star-forming and quiescent galaxies, exploiting both the rest frame U-V vs. V-J colour-colour diagram and the best fit values of the specific star formation rate (sSFR) from the SED fitting. Results: We found that the SN Ia rate per unit mass is higher by a factor of six in the star-forming galaxies with respect to the passive galaxies, identified as such both on the U-V vs. V-J colour-colour diagram and for their sSFR. The SN Ia rate per unit mass is also higher in the less massive galaxies that are also younger. These results suggest a distribution of the delay times (DTD) less populated at long delay times than at short delays. The CC SN rate per unit mass is proportional to both the sSFR and the galaxy

  2. Ultraviolet radiation from evolved stellar populations II. the ultraviolet upturn phenomenon in elliptical galaxies

    CERN Document Server

    Dorman, B; Rood, R T; Ben Dorman; Robert W O'Connell; Robert T Rood

    1994-01-01

    We present an analysis of the far-ultraviolet upturn phenomenon (UVX) observed in elliptical galaxies and spiral galaxy bulges. Our premise is that the UV radiation from these systems emanates primarily from extreme horizontal branch (EHB) stars and their progeny. We re-derive the broad-band UV colors 1500-V and 2500-V for globular clusters and elliptical galaxies from the available satellite data and investigate color-color and color-line strength correlations. We also provide the ingredients necessary for constructing models with arbitrary HB morphologies. Our models accurately predict the range of UV colors observed for the globular clusters, given known constraints on their age, abundances, and HB morphologies. Models with \\feh \\gta 0 which do not contain EHB stars cannot reproduce the colors of most of the galaxies. However, only small EHB fractions are required: \\lta 5\\% for the bulk of the E galaxies and \\sim 20\\% for those with the strongest UVX. Our models accurately predict the range of UV colors ob...

  3. 3D spectroscopy with VLT/GIRAFFE - II: Are Luminous Compact Galaxies merger remnants ?

    CERN Document Server

    Puech, M; Flores, H; Ostlin, G; Marquart, T

    2006-01-01

    Luminous Compact Galaxies are enigmatic sources by many aspects. They can reach the luminosity of the Milky Way within a radius of only a few kpc. They also represent one of the most rapidly evolving populations of galaxies since they represent up to 1/5 of the luminous galaxies at redshift z= 0.7 while being almost absent in the local Universe. The measurement of their dynamics is crucial to our understanding of LCGs since this has the potential of telling us which physical process(es) that drives them, and ultimately to link them to the existing present-day galaxies. Here we derive the 3 dimensional velocity fields and velocity dispersion (sigma) maps of 17 Luminous Compact Galaxies selected from the Canada France Redshift Survey and the Hubble Deep Field South with redshifts ranging from z=0.4 to z=0.75. We find that only 18% of them show rotational velocity fields typical of rotating disks, the others showing more complex kinematics. Assuming that LCGs are not too far from equilibrium, about half of LCGs ...

  4. Southern GEMS groups II: HI distribution, mass functions and HI deficient galaxies

    CERN Document Server

    Kilborn, Virginia A; Barnes, David G; Koribalski, Baerbel S; Brough, Sarah; Kern, Katie

    2009-01-01

    We investigate the neutral hydrogen (HI) content of sixteen groups for which we have multi-wavelength data including X-ray observations. Wide-field imaging of the groups was obtained with the 20-cm multibeam system on the 64-m Parkes telescope. We have detected ten previously uncatalogued HI sources, one of which has no visible optical counterpart. We examine the HI properties of the groups, compared to their X-ray characteristics, finding that those groups with a higher X-ray temperature and luminosity contain less HI per galaxy. The HI content of a group depends on its morphological make-up, with those groups dominated by early-type galaxies containing the least total HI. We determined the expected HI for the spiral galaxies in the groups, and found that a number of the galaxies were HI deficient. The HI deficient spirals were found both in groups with and without a hot intra-group medium. The HI deficient galaxies were not necessarily found at the centre of the groups, however, we did find that two thirds ...

  5. AN H I SURVEY OF SIX LOCAL GROUP ANALOGS. II. H I PROPERTIES OF GROUP GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Pisano, D. J. [Department of Physics, West Virginia University, P.O. Box 6315, Morgantown, WV 26506 (United States); Barnes, David G.; Kilborn, Virginia A. [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, Victoria 3122 (Australia); Staveley-Smith, Lister [International Centre for Radio Astronomy Research, M468, University of Western Australia, Crawley, WA 6009 (Australia); Gibson, Brad K. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Freeman, Ken C., E-mail: djpisano@mail.wvu.edu, E-mail: David.G.Barnes@gmail.com, E-mail: vkilborn@astro.swin.edu.au, E-mail: Lister.Staveley-Smith@icrar.org, E-mail: brad.k.gibson@gmail.com, E-mail: kcf@mso.anu.edu.au [RSAA, Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia)

    2011-12-01

    We have conducted an H I 21 cm emission-line survey of six loose groups of galaxies chosen to be analogs to the Local Group. The survey was conducted using the Parkes multibeam instrument and the Australia Telescope Compact Array (ATCA) over a {approx}1 Mpc{sup 2} area and covering the full depth of each group, with an M{sub HI} sensitivity of {approx}7 Multiplication-Sign 10{sup 5} M{sub Sun }. Our survey detected 110 sources, 61 of which are associated with the six groups. All of these sources were confirmed with ATCA observations or were previously cataloged by HIPASS. The sources all have optical counterparts and properties consistent with dwarf irregular or late-type spiral galaxies. We present here the H I properties of the groups and their galaxies. We derive an H I mass function (HIMF) for the groups that is consistent with being flatter than the equivalent field HIMF. We also derive a circular velocity distribution function, tracing the luminous dark matter halos in the groups, that is consistent with those of the Local Group and HIPASS galaxies, both of which are shallower than that of clusters or predictions from cold dark matter models of galaxy formation.

  6. ALFALFA HI Data Stacking II. HI content of the host galaxies of AGN

    CERN Document Server

    Fabello, S; Catinella, B; Giovanelli, R; Haynes, M P; Heckman, T M; Schiminovich, D

    2011-01-01

    We use a stacking technique to measure the average HI content of a volume-limited sample of 1871 AGN host galaxies from a parent sample of galaxies selected from the SDSS and GALEX imaging surveys with stellar masses greater than 10^10 M_sun and redshifts in the range 0.025galaxies correlates most strongly with the combination of optical/UV colour and stellar surface mass density. We therefore build a control sample of non-AGN matched to the AGN hosts in these two properties. We study trends in HI gas mass fraction (M(HI)/M_*), where M_* is the stellar mass) as a function of black hole accretion rate indicator L[OIII]/M(BH). We find no significant difference in HI content between AGN and control samples at all values of black hole accretion rate probed by the galaxies in our sample. This indicates that AGN do not influence the large-scale gaseous properties of galaxie...

  7. The Evolutionary Status of Isolated Dwarf Irregular Galaxies II. Star Formation Histories and Gas Depletion

    CERN Document Server

    Van Zee, L

    2001-01-01

    The results of UBV and H alpha imaging of a large sample of isolated dwarf irregular galaxies are interpreted in the context of composite stellar population models. The observed optical colors are best fit by composite stellar populations which have had approximately constant star formation rates for at least 10 Gyr. The galaxies span a range of central surface brightness, from 20.5 to 25.0 mag arcsec^{-2}; there is no correlation between surface brightness and star formation history. Although the current star formation rates are low, it is possible to reproduce the observed luminosities without a major starburst episode. The derived gas depletion timescales are long, typically ~20 Gyr. These results indicate that dwarf irregular galaxies will be able to continue with their slow, but constant, star formation activity for at least another Hubble time. The sample of isolated dIs is compared to a sample of star bursting dwarf galaxies taken from the literature. The star bursting dwarf galaxies have many similar ...

  8. Preparation and characterization of a novel nano-absorbent based on multi-cyanoguanidine modified magnetic chitosan and its highly effective recovery for Hg(II) in aqueous phase

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yang; Qi, Yongxin; Li, Yanfeng, E-mail: liyf@lzu.edu.cn; Wu, Jianjun; Ma, Xiaojie; Yu, Cui; Ji, Lei

    2013-09-15

    Highlights: • The multi-cyanoguanidine modified magnetic chitosan was firstly synthesized. • Introduce more functional group by modification of cross-linking agent. •The absorbent showed the prominent adsorption capacity and strong removal ability. • The absorbent shows excellent selectively separate for Hg(II). -- Abstract: A new kind of nano-absorbent with the entirely novel structure, nano-absorbent of multi-cyanogunidine modified magnetic chitosan (CG-MCS nano-absorbent), has been firstly synthesized by using the functionalized chitosan and cross-linking agent with cyanoguanidine group simultaneously. The resulting nano-absorbent was characterized by means of the Fourier transform infrared spectra (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), elemental analysis and vibrating sample magnetometer (VSM). The resulting nano-absorbent basen on multi-cyanoguanidine modified magnetic chitosan has been demonstrated holding highly effective recovery for mercury ions, in other words, it showed both the extraordinary adsorption capacity for Hg(II) at high initial concentration and the strong removal ability for it at low concentration, the maximum adsorption capacity was up to 285 mg g{sup −1} and the removal percentage could reach 96% at low concentration. Meanwhile, the resulting CG-MCS nano-absorbent also showed a high selectivity adsorption for Hg(II) among coexisting heavy metals and the good regeneration performance.

  9. On the lack of correlation between Mg II 2796, 2803 Å and Lyα emission in lensed star-forming galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Rigby, J. R. [Astrophysics Science Division, Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Bayliss, M. B. [Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138 (United States); Gladders, M. D. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 (United States); Sharon, K. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Wuyts, E. [Max Plank Institute for Extraterrestrial Physics, Giessenbachstrasse 1, D-85748 Garching (Germany); Dahle, H. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway)

    2014-07-20

    We examine the Mg II 2796, 2803 Å, Lyα, and nebular line emission in five bright star-forming galaxies at 1.66 < z < 1.91 that have been gravitationally lensed by foreground galaxy clusters. All five galaxies show prominent Mg II emission and absorption in a P Cygni profile. We find no correlation between the equivalent widths of Mg II and Lyα emission. The Mg II emission has a broader range of velocities than do the nebular emission line profiles; the Mg II emission is redshifted with respect to systemic by 100-200 km s{sup –1}. When present, Lyα is even more redshifted. The reddest components of Mg II and Lyα emission have tails to 500-600 km s{sup –1}, implying a strong outflow. The lack of correlation in the Mg II and Lyα equivalent widths, the differing velocity profiles, and the high ratios of Mg II to nebular line fluxes together suggest that the bulk of Mg II emission does not ultimately arise as nebular line emission, but may instead be reprocessed stellar continuum emission.

  10. On the Lack of Correlation Between Mg II 2796, 2803 Angstrom and Lyman alpha Emission in Lensed Star-Forming Galaxies

    Science.gov (United States)

    Rigby, Jane Rebecca; Bayliss, M. B.; Gladders, M. D.; Sharon, K.; Wuyts, E.; Dahle, H.

    2014-01-01

    We examine the Mg II 2796, 2803 Angstrom, Lyman alpha, and nebular line emission in five bright star-forming galaxies at 1.66 less than z less than 1.91 that have been gravitationally lensed by foreground galaxy clusters. All five galaxies show prominent Mg II emission and absorption in a P Cygni profile. We find no correlation between the equivalent widths of Mg II and Lyman alpha emission. The Mg II emission has a broader range of velocities than do the nebular emission line profiles; the Mg II emission is redshifted with respect to systemic by 100 to 200 km s(exp-1). When present, Lyman alpha is even more redshifted. The reddest components of Mg II and Lyman alpha emission have tails to 500-600 km s(exp-1), implying a strong outflow. The lack of correlation in the Mg II and Lyman alpha equivalent widths, the differing velocity profiles, and the high ratios of Mg II to nebular line fluxes together suggest that the bulk of Mg II emission does not ultimately arise as nebular line emission, but may instead be reprocessed stellar continuum emission.

  11. Supermassive black holes and their host galaxies. II. The correlation with near-infrared luminosity revisited

    Energy Technology Data Exchange (ETDEWEB)

    Läsker, Ronald; Van de Ven, Glenn [Max-Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Ferrarese, Laura [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E2E7 (Canada); Shankar, Francesco, E-mail: laesker@mpia.de [GEPI Observatoire de Paris, CNRS, Univ. Paris Diderot, 5 Place Jules Janssen, F-92195 Meudon (France)

    2014-01-01

    We present an investigation of the scaling relations between supermassive black hole (SMBH) masses, M {sub •}, and their host galaxies' K-band bulge (L {sub bul}) and total (L {sub tot}) luminosities. The wide-field WIRCam imager at the Canada-France-Hawaii-Telescope was used to obtain the deepest and highest resolution near-infrared images available for a sample of 35 galaxies with securely measured M {sub •}, selected irrespective of Hubble type. For each galaxy, we derive bulge and total magnitudes using a two-dimensional image decomposition code that allows us to account, if necessary, for large- and small-scale disks, cores, bars, nuclei, rings, envelopes, and spiral arms. We find that the present-day M {sub •}-L {sub bul} and M {sub •}-L {sub tot} relations have consistent intrinsic scatter, suggesting that M {sub •} correlates equally well with bulge and total luminosity of the host. Our analysis provides only mild evidence of a decreased scatter if the fit is restricted to elliptical galaxies. The log-slopes of the M {sub •}-L {sub bul} and M {sub •}-L {sub tot} relations are 0.75 ± 0.10 and 0.92 ± 0.14, respectively. However, while the slope of the M {sub •}-L {sub bul} relation depends on the detail of the image decomposition, the characterization of M {sub •}-L {sub tot} does not. Given the difficulties and ambiguities of decomposing galaxy images into separate components, our results indicate that L {sub tot} is more suitable as a tracer of SMBH mass than L {sub bul}, and that the M {sub •}-L {sub tot} relation should be used when studying the co-evolution of SMBHs and galaxies.

  12. Galaxy evolution in cosmological simulations with outflows - II. Metallicities and gas fractions

    Science.gov (United States)

    Davé, Romeel; Finlator, Kristian; Oppenheimer, Benjamin D.

    2011-09-01

    We use cosmological hydrodynamic simulations to investigate how inflows, star formation and outflows govern the gaseous and metal content of galaxies within a hierarchical structure formation context. In our simulations, galaxy metallicities are established by a balance between inflows and outflows as governed by the mass outflow rate, implying that the mass-metallicity relation reflects how the outflow rate varies with stellar mass. Gas content, meanwhile, is set by a competition between inflow into and gas consumption within the interstellar medium, the latter being governed by the star formation law, while the former is impacted by both wind recycling and preventive feedback. Stochastic variations in the inflow rate move galaxies off the equilibrium mass-metallicity and mass-gas fraction relations in a manner correlated with the star formation rate, and the scatter is set by the time-scale to re-equilibrate. The evolution of both relations from z= 3 → 0 is slow, as individual galaxies tend to evolve mostly along the relations. Gas fractions at a given stellar mass slowly decrease with time because the cosmic inflow rate diminishes faster than the consumption rate, while metallicities slowly increase as infalling gas becomes more enriched. Observations from z˜ 3 → 0 are better matched by simulations employing momentum-driven wind scalings rather than constant wind speeds, but all models predict too low gas fractions at low masses and too high metallicities at high masses. All our models reproduce observed second-parameter trends of the mass-metallicity relation with the star formation rate and environment, indicating that these are a consequence of equilibrium and not feedback. Overall, the analytical framework of our equilibrium scenario broadly captures the relevant physics establishing the galaxy gas and metal content in simulations, which suggests that the cycle of baryonic inflows and outflows centrally governs the cosmic evolution of these properties

  13. On star formation in stellar systems. II - Photoionization in protodwarf galaxies

    Science.gov (United States)

    Noriega-Crespo, A.; Bodenheimer, P.; Lin, D. N. C.; Tenorio-Tagle, G.

    1989-01-01

    Numerical hydrodynamical calculations are used to study the effects of the onset of star formation on the residual gas in a primordial low-mass Local-Group dwarf spheroidal galaxy in the size range 0.3-1.0 kpc. It is demonstrated that photoionization in the presence of a moderate gas-density gradient can be responsible for gas ejection on a time-scale of a few times 10 to the 7th yr. The results indicate that, given a normal initial mass function, many protodwarf galaxies may have been dispersed by the onset of star formation.

  14. Absorbing Outflows in AGN

    Science.gov (United States)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  15. 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...

  16. Halpha3: an Halpha imaging survey of HI selected galaxies from ALFALFA. II. The star formation properties of galaxies in the Virgo cluster and surroundings

    CERN Document Server

    Gavazzi, Giuseppe; Fossati, Matteo; Galardo, Vincenzo; Grossetti, Francesco; Boselli, Alessandro; Giovanelli, Riccardo; Haynes, Martha P

    2013-01-01

    We present the analysis of Halpha3, an Halpha imaging survey of 409 galaxies selected from the HI Arecibo ALFALFA Survey in the Local Supercluster, including the Virgo cluster. We explore the relations between the stellar mass, the HI mass and the current, massive SFR of nearby galaxies in the Virgo cluster and we compare them with those of isolated galaxies in the Local Supercluster, disentangling the role of the environment in shaping the star formation properties of galaxies at the present cosmological epoch. We investigate the relationships between atomic neutral gas and newly formed stars in different environments, across many morphological types, and over a wide range of stellar masses adopting an updated calibration of the HI deficiency parameter. Studying the mean properties of late-type galaxies in the Local Supercluster, we find that galaxies in increasing local galaxy density conditions (or decreasing projected angular separation from M87) show a significant decrease in the HI content and in the me...

  17. AN INDEPENDENT MEASUREMENT OF THE INCIDENCE OF Mg II ABSORBERS ALONG GAMMA-RAY BURST SIGHT LINES: THE END OF THE MYSTERY?

    Energy Technology Data Exchange (ETDEWEB)

    Cucchiara, A.; Prochaska, J. X. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Zhu, G.; Menard, B. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Fynbo, J. P. U. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Fox, D. B. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Chen, H.-W. [Department of Astronomy and Astrophysics, Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Cooksey, K. L. [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-685, Cambridge, MA 02139 (United States); Cenko, S. B.; Bloom, J. S. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Perley, D. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd., Pasadena, CA 91125 (United States); Berger, E.; Chornock, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); D' Elia, V. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Roma, Via di Frascati 33, I-00040 Monte Porzio Catone (RM) (Italy); Lopez, S.; De Jaeger, T., E-mail: acucchia@ucolick.org [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile)

    2013-08-20

    In 2006, Prochter et al. reported a statistically significant enhancement of very strong Mg II absorption systems intervening the sight lines to gamma-ray bursts (GRBs) relative to the incidence of such absorption along quasar sight lines. This counterintuitive result has inspired a diverse set of astrophysical explanations (e.g., dust, gravitational lensing) but none of these has obviously resolved the puzzle. Using the largest set of GRB afterglow spectra available, we reexamine the purported enhancement. In an independent sample of GRB spectra with a survey path three times larger than Prochter et al., we measure the incidence per unit redshift of {>=}1 A rest-frame equivalent width Mg II absorbers at z Almost-Equal-To 1 to be l(z) = 0.18 {+-} 0.06. This is fully consistent with current estimates for the incidence of such absorbers along quasar sight lines. Therefore, we do not confirm the original enhancement and suggest those results suffered from a statistical fluke. Signatures of the original result do remain in our full sample (l(z) shows an Almost-Equal-To 1.5 enhancement over l(z){sub QSO}), but the statistical significance now lies at Almost-Equal-To 90% c.l. Restricting our analysis to the subset of high-resolution spectra of GRB afterglows (which overlaps substantially with Prochter et al.), we still reproduce a statistically significant enhancement of Mg II absorption. The reason for this excess, if real, is still unclear since there is no connection between the rapid afterglow follow-up process with echelle (or echellette) spectrographs and the detectability of strong Mg II doublets. Only a larger sample of such high-resolution data will shed some light on this matter.

  18. OMEGA - OSIRIS Mapping of Emission-line Galaxies in A901/2: II. - Environmental influence on integrated star formation properties and AGN activity

    Science.gov (United States)

    Rodríguez del Pino, Bruno; Aragón-Salamanca, Alfonso; Chies-Santos, Ana L.; Weinzirl, Tim; Bamford, Steven P.; Gray, Meghan E.; Böhm, Asmus; Wolf, Christian; Maltby, David T.

    2017-01-01

    We present a study of the star formation and AGN activity for galaxies in the Abell 901/2 multi-cluster system at z ˜ 0.167 as part of the OMEGA survey. Using Tuneable Filter data obtained with the OSIRIS instrument at the GTC we produce spectra covering the Hα and [N II] spectral lines for more than 400 galaxies. Using optical emission-line diagnostics, we identify a significant number of galaxies hosting AGN, which tend to have high masses and a broad range of morphologies. Moreover, within the environmental densities probed by our study, we find no environmental dependence on the fraction of galaxies hosting AGN. The analysis of the integrated Hα emission shows that the specific star formation rates (SSFRs) of a majority of the cluster galaxies are below the field values for a given stellar mass. We interpret this result as evidence for a slow decrease in the star formation activity of star-forming galaxies as they fall into higher-density regions, contrary to some previous studies which suggested a rapid truncation of star formation. We find that most of the intermediate- and high-mass spiral galaxies go through a phase in which their star formation is suppressed but still retain significant star-formation activity. During this phase, these galaxies tend to retain their spiral morphology while their colours become redder. The presence of this type of galaxies in high density regions indicates that the physical mechanism responsible for suppressing star-formation affects mainly the gas component of the galaxies, suggesting that ram-pressure stripping or starvation are potentially responsible.

  19. Scientific Opinion on the safety evaluation of the active substance iron (II modified bentonite as oxygen absorber for use in active food contact materials

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

    2012-10-01

    Full Text Available

    This scientific opinion of EFSA deals with the safety evaluation of the active substance iron (II modified bentonite (FCM Substance No 1003 intended to be incorporated in monolayer or multilayer packages or in sachets for absorbing oxygen from the food environment. All starting substances of the oxygen absorber have been evaluated and approved for use as additives in plastic food contact materials or as food additives. From a toxicological point of view, migration of iron (incorporated and aluminium (naturally present ions from bentonite is of interest. Iron can be estimated to migrate up to 4.5 mg/kg acidic food, which is well below the SML value of 48 mg/kg food set in Regulation EU No 10/2011 based on the PMTDI of 0.8 mg/kg bw established by the Joint FAO/WHO Expert Committee on Food Additives in 1983 and the SCF in 1990. The iron (II modified bentonite is intended and expected to be present in the final article as non-nanoform. However, the formation of nanoparticles due to exfoliation cannot be excluded if the substance is incorporated in unpolar polymers with compatibilisers or without such additives in polar polymers. Aluminium can be estimated to migrate up to 0.3 mg /kg acidic food. This value corresponds to 3.5 % of the TWI set in 2008 by the EFSA AFC Panel. Therefore, under the intended conditions of use, the oxygen absorber formulation was considered toxicologically acceptable. The CEF Panel concluded that the substance iron (II modified bentonite does not raise a safety concern for the consumer when used as oxygen absorber incorporated without compatibilisers in polyolefin layers of food packages at levels up to 15% w/w. The substance equally does not raise a safety concern when it is used in sachets, placed in the headspace of the packaging, that prevent the physical release of their contents into the food and are not in direct contact with liquid foods, exudates, or foods with external aqueous liquid phase.

  20. ISO far-infrared observations of rich galaxy clusters II. Sersic 159-03

    DEFF Research Database (Denmark)

    Hansen, Lene; Jørgensen, H.E.; Nørgaard-Nielsen, Hans Ulrik

    2000-01-01

    In a series of papers we investigate far-infrared emission from rich galaxy clusters. Maps have been obtained by ISO at 60 mu m, 100 mu m, 135 mu m, and 200 mu m using the PHT-C camera. Ground based imaging and spectroscopy were also acquired. Here we present the results for the cooling flow...

  1. Fundamental parameters of FR II radio galaxies and their impact on groups and clusters' environments

    NARCIS (Netherlands)

    Kapińska, A.D.; Uttley, P.

    2013-01-01

    Radio galaxies are among the largest and most powerful single objects known and are found at variety of redshifts, hence they are believed to have had a significant impact on the evolving Universe. Their relativistic jets inject considerable amounts of energy into the environments in which the sourc

  2. Galaxy Cluster Mass Reconstruction Project: II. Quantifying scatter and bias using contrasting mock catalogues

    CERN Document Server

    Old, L; Mamon, G A; Skibba, R A; Pearce, F R; Croton, D; Bamford, S; Behroozi, P; de Carvalho, R; Muñoz-Cuartas, J C; Gifford, D; Gray, M E; von der Linden, A; Merrifield, M R; Muldrew, S I; Müller, V; Pearson, R J; Ponman, T J; Rozo, E; Rykoff, E; Saro, A; Sepp, T; Sifón, C; Tempel, E

    2015-01-01

    This article is the second in a series in which we perform an extensive comparison of various galaxy-based cluster mass estimation techniques that utilise the positions, velocities and colours of galaxies. Our aim is to quantify the scatter, systematic bias and completeness of cluster masses derived from a diverse set of 25 galaxy-based methods using two contrasting mock galaxy catalogues based on a sophisticated halo occupation model and a semi-analytic model. Analysing 968 clusters, we find a wide range in the RMS errors in log M200c delivered by the different methods (0.18 to 1.08 dex, i.e., a factor of ~1.5 to 12), with abundance matching and richness methods providing the best results, irrespective of the input model assumptions. In addition, certain methods produce a significant number of catastrophic cases where the mass is under- or over-estimated by a factor greater than 10. Given the steeply falling high-mass end of the cluster mass function, we recommend that richness or abundance matching-based me...

  3. The MICE Grand Challenge lightcone simulation - II. Halo and galaxy catalogues

    Science.gov (United States)

    Crocce, M.; Castander, F. J.; Gaztañaga, E.; Fosalba, P.; Carretero, J.

    2015-10-01

    This is the second in a series of three papers in which we present an end-to-end simulation from the MICE collaboration, the MICE Grand Challenge (MICE-GC) run. The N-body contains about 70 billion dark-matter particles in a (3 h-1 Gpc)3 comoving volume spanning five orders of magnitude in dynamical range. Here, we introduce the halo and galaxy catalogues built upon it, both in a wide (5000 deg2) and deep (z characteristic scale-dependent bias of ≲6 per cent across the BAO feature for haloes well above M⋆ ˜ 1012 h-1 M⊙ and for luminous red galaxy like galaxies. For haloes well below M⋆ the scale dependence at 100 h-1 Mpc is ≲2 per cent. Lastly, we discuss the validity of the large-scale Kaiser limit across redshift and departures from it towards non-linear scales. We make the current version of the lightcone halo and galaxy catalogue (MICECATv1.0) publicly available through a dedicated web portal to help develop and exploit the new generation of astronomical surveys.

  4. Mass Transport and Turbulence in Gravitationally Unstable Disk Galaxies II: The Effects of Star Formation Feedback

    CERN Document Server

    Goldbaum, Nathan J; Forbes, John C

    2016-01-01

    Self-gravity and stellar feedback are capable of driving turbulence and transporting mass and angular momentum in disk galaxies, but the balance between them is not well understood. In the previous paper in this series, we showed that gravity alone can drive turbulence in galactic disks, regulate their Toomre $Q$ parameters to $\\sim$ 1, and transport mass inwards at a rate sufficient to fuel star formation in the centers of present-day galaxies. In this paper we extend our models to include the effects of star formation feedback. We show that feedback suppresses galaxies' star formation rates by a factor of $\\sim$ 5 and leads to the formation of a multi-phase atomic and molecular ISM. Both the star formation rate and the phase balance produced in our simulations agree well with observations of nearby spirals. After our galaxies reach steady state, we find that the inclusion of feedback actually lowers the gas velocity dispersion slightly compared to the case of pure self-gravity, and also slightly reduces the...

  5. 3D spectroscopy with VLT/GIRAFFE. II. Are luminous compact galaxies merger remnants?

    Science.gov (United States)

    Puech, M.; Hammer, F.; Flores, H.; Östlin, G.; Marquart, T.

    2006-08-01

    Luminous Compact Galaxies (LCGs) are enigmatic sources in many aspects. They can reach the luminosity of the Milky Way within a radius of only a few kpc. They also represent one of the most rapidly evolving populations of galaxies since they represent up to 1/5 of the luminous galaxies at redshift z= 0.7, while being almost absent in the local Universe. The measurement of their dynamics is crucial to our understanding of LCGs since this has the potential of telling us which physical process(es) drive(s) them and ultimately link them to the existing present-day galaxies. Here, we derive the 3-dimensional velocity fields and velocity dispersion (σ) maps of 17 LCGs selected from the Canada France Redshift Survey and the Hubble Deep Field South with redshifts ranging from z=0.4 to z=0.75. We find that only 18% of them show rotational velocity fields typical of rotating disks while the others show more complex kinematics. Assuming that LCGs are not too far from equilibrium, about half of LCGs then appear to be either non-relaxed objects, or objects that are not supported by velocity dispersion alone. This supports the view that an important fraction of LCGs are probably mergers. It brings additional support to the "spiral rebuilding scenario" in which LCGs correspond to a previous or post-merger phase before the disk re-building.

  6. Hierarchical formation of bulgeless galaxies II: Redistribution of angular momentum via galactic fountains

    CERN Document Server

    Brook, C B; Gibson, B K; Roškar, R; Wadsley, J; Quinn, T

    2011-01-01

    Within a fully cosmological hydrodynamical simulation, we form a galaxy which rotates at 140 km/s, and is characterised by two loose spiral arms and a bar, indicative of a Hubble Type SBc/d galaxy. We show that our simulated galaxy has no classical bulge, with a pure disc profile at z=1, well after the major merging activity has ended. A long-lived bar subsequently forms, resulting in the formation of a secularly-formed "pseudo" bulge, with the final bulge-to-total light ratio B/T=0.21. We show that the majority of gas which loses angular momentum and falls to the central region of the galaxy during the merging epoch is blown back into the hot halo, with much of it returning later to form stars in the disc. We propose that this mechanism of redistribution of angular momentum via a galactic fountain, when coupled with the results from our previous study which showed why gas outflows are biased to have low angular momentum, can solve the angular momentum/bulgeless disc problem of the cold dark matter paradigm.

  7. RHAPSODY-G simulations - II. Baryonic growth and metal enrichment in massive galaxy clusters

    Science.gov (United States)

    Martizzi, Davide; Hahn, Oliver; Wu, Hao-Yi; Evrard, August E.; Teyssier, Romain; Wechsler, Risa H.

    2016-07-01

    We study the evolution of the stellar component and the metallicity of both the intracluster medium and of stars in massive (Mvir ≈ 6 × 1014 M⊙ h-1) simulated galaxy clusters from the RHAPSODY-G suite in detail and compare them to observational results. The simulations were performed with the AMR code RAMSES and include the effect of active galactic nucleus (AGN) feedback at the subgrid level. AGN feedback is required to produce realistic galaxy and cluster properties and plays a role in mixing material in the central regions and regulating star formation in the central galaxy. In both our low- and high-resolution runs with fiducial stellar yields, we find that stellar and ICM metallicities are a factor of 2 lower than in observations. We find that cool core clusters exhibit steeper metallicity gradients than non-cool core clusters, in qualitative agreement with observations. We verify that the ICM metallicities measured in the simulation can be explained by a simple `regulator' model in which the metallicity is set by a balance of stellar yield and gas accretion. It is plausible that a combination of higher resolution and higher metal yield in AMR simulation would allow the metallicity of simulated clusters to match observed values; however, this hypothesis needs to be tested with future simulations. Comparison to recent literature highlights that results concerning the metallicity of clusters and cluster galaxies might depend sensitively on the scheme chosen to solve the hydrodynamics.

  8. Galaxy Evolution in Cosmological Simulations with Outflows II: Metallicities and Gas Fractions

    CERN Document Server

    Davé, Romeel; Oppenheimer, Benjamin D

    2011-01-01

    We use cosmological hydrodynamic simulations to investigate how inflows, star formation, and outflows govern the the gaseous and metal content of galaxies. In our simulations, galaxy metallicities are established by a balance between inflows and outflows as governed by the mass outflow rate, implying that the mass-metallicity relation reflects how the outflow rate varies with stellar mass. Gas content is set by a competition between inflow into and gas consumption within the ISM, the latter being governed by the star formation law, while the former is impacted by both wind recycling and preventive feedback. Stochasticity in the inflow rate moves galaxies off the equilibrium mass-metallicity and mass-gas fraction relations in a manner correlated with the SFR, and the scatter is set by the timescale to re-equilibrate. The evolution of both relations from z=3-0 is slow, as individual galaxies tend to evolve mostly along the relations. Gas fractions at a given stellar mass slowly decrease with time because the co...

  9. ISO far-infrared observations of rich galaxy clusters II. Sersic 159-03

    DEFF Research Database (Denmark)

    Hansen, Lene; Jørgensen, H.E.; Nørgaard-Nielsen, Hans Ulrik

    2000-01-01

    In a series of papers we investigate far-infrared emission from rich galaxy clusters. Maps have been obtained by ISO at 60 mu m, 100 mu m, 135 mu m, and 200 mu m using the PHT-C camera. Ground based imaging and spectroscopy were also acquired. Here we present the results for the cooling flow...

  10. An HI Survey of Six Local Group Analogs. II. HI properties of group galaxies

    CERN Document Server

    Pisano, D J; Staveley-Smith, L; Gibson, B K; Kilborn, V A; Freeman, K C

    2011-01-01

    We have conducted an HI 21 cm emission-line survey of six loose groups of galaxies chosen to be analogs to the Local Group. The survey was conducted using the Parkes Multibeam instrument and the Australia Telescope Compact Array (ATCA) over a ~1 Mpc^2 area and covering the full depth of each group, with a M(HI) sensitivity of ~7x10^5 M(sun). Our survey detected 110 sources, 61 of which are associated with the six groups. All of these sources were confirmed with ATCA observations or were previously cataloged by HIPASS. The sources all have optical counterparts and properties consistent with dwarf irregular or late-type spiral galaxies. We present here the HI properties of the groups and their galaxies. We derive an HI mass function for the groups that is consistent with being flatter than the equivalent field HIMF. We also derive a circular velocity distribution function, tracing the luminous dark matter halos in the groups, that is consistent with those of the Local Group and HIPASS galaxies, both of which ar...

  11. Dark influences II: gas and star formation in minor mergers of dwarf galaxies with dark satellites

    CERN Document Server

    Starkenburg, Tjitske K; Sales, Laura V

    2015-01-01

    Mergers have been proposed to induce starbursts and to lead to important morphological changes in galaxies. Most studies so far have focused on large galaxies, but dwarfs might also experience such events, since the halo mass function is scale-free in the concordance cosmological model. Notably, because of their low mass, most of their interactions will be with dark satellites. In this paper we follow the evolution of gas-rich disky dwarf galaxies as they experience a minor merger with a dark satellite. We aim to characterize the effects of such an interaction on the dwarf's star formation, morphology and kinematical properties. We perform a suite of carefully set-up hydrodynamical simulations of dwarf galaxies that include dark matter, gas, and stars, merging with a satellite consisting solely of dark matter. For the host system we vary the gas fraction, disk size and thickness, halo mass and concentration, while for the satellite we explore different masses, concentrations and orbits. We find that the inter...

  12. Dark Matter Halos in Galaxies and Globular Cluster Populations. II: Metallicity and Morphology

    CERN Document Server

    Harris, William; Hudson, Michael

    2015-01-01

    An increasing body of data reveals a one-to-one linear correlation between galaxy halo mass and the total mass in its globular cluster (GC) population, M_{GCS} ~ M_h^{1.03 \\pm 0.03}, valid over 5 orders of magnitude. We explore the nature of this correlation for galaxies of different morphological types, and for the subpopulations of metal-poor (blue) and metal-rich (red) GCs. For the subpopulations of different metallicity we find M_{GCS}(blue) ~ M_h^{0.96 \\pm 0.03} and M_{GCS}(red) ~ M_h^{1.21 \\pm 0.03} with similar scatter. The numerical values of these exponents can be derived from the detailed behavior of the red and blue GC fractions with galaxy mass and provide a self-consistent set of relations. In addition, all morphological types (E, S0, S/Irr) follow the same relation, but with a second-order trend for spiral galaxies to have a slightly higher fraction of metal-rich GCs for a given mass. These results suggest that the amount of gas available for GC formation at high redshift was in nearly direct pr...

  13. The Herschel Fornax Cluster Survey II: FIR properties of optically-selected Fornax cluster galaxies

    CERN Document Server

    Fuller, C; Auld, R; Smith, M W L; Baes, M; Bianchi, S; Bocchio, M; Boselli, A; Clemens, M; Davis, T A; De Looze, I; Alighieri, S di Serego; Grossi, M; Hughes, T M; Viaene, S; Serra, P

    2014-01-01

    The $Herschel$ Fornax Cluster Survey (HeFoCS) is a deep, far-infrared (FIR) survey of the Fornax cluster. The survey is in 5 $Herschel$ bands (100 - 500 $\\mu$m) and covers an area of 16 deg$^2$ centred on NGC1399. This paper presents photometry, detection rates, dust masses and temperatures using an optically selected sample from the Fornax Cluster Catalogue (FCC). Our results are compared with those previously obtained using data from the $Herschel$ Virgo Cluster Survey (HeViCS). In Fornax, we detect 30 of the 237 (13%) optically selected galaxies in at least one $Herschel$ band. The global detection rates are significantly lower than Virgo, reflecting the morphological make up of each cluster - Fornax has a lower fraction of late-type galaxies. For galaxies detected in at least 3 bands we fit a modified blackbody with a $\\beta = 2$ emissivity. Detected early-type galaxies (E/S0) have a mean dust mass, temperature, and dust-to-stars ratio of $\\log_{10}(/\\mathrm{M_{\\odot}}) = 5.82 \\pm 0.20$, $ = 20.82 \\pm 1.7...

  14. Shocked POststarburst Galaxy Survey II: The Molecular Gas Content and Properties of a Subset of SPOGs

    CERN Document Server

    Alatalo, Katherine; Lanz, Lauranne; Appleton, Philip N; Cales, Sabrina L; Kewley, Lisa J; Lacy, Mark; Medling, Anne M; Nyland, Kristina; Rich, Jeffrey A; Urry, C Meg

    2016-01-01

    We present CO(1-0) observations of objects within the Shocked POststarburst Galaxy Survey taken with the Institut de Radioastronomie Millimetrique (IRAM) 30m single dish and the Combined Array for Research for Millimeter Astronomy (CARMA) interferometer. Shocked Poststarburst Galaxies (SPOGs) represent a transitioning population of galaxies, with deep Balmer absorption (Hdelta>5A), consistent with an intermediate-age (A-star) stellar population, and ionized gas line ratios inconsistent with pure star formation. The CO(1-0) subsample was selected from SPOGs detected by the Wide-field Infrared Survey Explorer with 22um flux detected at a signal-to-noise (S/N)>3. Of the 52 objects observed in CO(1-0), 47 are detected with S/N>3. A large fraction (37-46%) of our CO-SPOG sample were visually classified as morphologically disrupted. The H2 masses detected were between 10^(8.7-10.8) Msuns, consistent with the gas masses found in normal galaxies, though approximately an order of magnitude larger than the range seen i...

  15. Shocked POststarburst Galaxy Survey. II. The Molecular Gas Content and Properties of a Subset of SPOGs

    Science.gov (United States)

    Alatalo, Katherine; Lisenfeld, Ute; Lanz, Lauranne; Appleton, Philip N.; Ardila, Felipe; Cales, Sabrina L.; Kewley, Lisa J.; Lacy, Mark; Medling, Anne M.; Nyland, Kristina; Rich, Jeffrey A.; Urry, C. Meg

    2016-08-01

    We present CO(1-0) observations of objects within the Shocked POststarburst Galaxy Survey taken with the Institut de Radioastronomie Millimétrique 30 m single dish and the Combined Array for Research for Millimeter Astronomy interferometer. Shocked poststarburst galaxies (SPOGs) represent a transitioning population of galaxies, with deep Balmer absorption ({{EW}}{{H}δ }\\gt 5 {\\mathring{{A}}} ), consistent with an intermediate-age (A-star) stellar population, and ionized gas line ratios inconsistent with pure star formation. The CO(1-0) subsample was selected from SPOGs detected by the Wide-field Infrared Survey Explorer with 22 μm flux detected at a signal-to-noise ratio (S/N) > 3. Of the 52 objects observed in CO(1-0), 47 are detected with S/N > 3. A large fraction (37%-46% ± 7%) of our CO-SPOG sample were visually classified as morphologically disrupted. The H2 masses detected were between {10}8.7-10.8 {M}⊙ , consistent with the gas masses found in normal galaxies, though approximately an order of magnitude larger than the range seen in poststarburst galaxies. When comparing the 22 μm and CO(1-0) fluxes, SPOGs diverge from the normal star-forming relation, having 22 μm fluxes in excess of the relation by a factor of ={4.91}-0.39+0.42, suggestive of the presence of active galactic nuclei (AGNs). The Na i D characteristics of CO-SPOGs show that it is likely that many of these objects host interstellar winds. Objects with large Na i D enhancements also tend to emit in the radio, suggesting possible AGN driving of neutral winds.

  16. HICOSMO: cosmology with a complete sample of galaxy clusters - II. Cosmological results

    Science.gov (United States)

    Schellenberger, G.; Reiprich, T. H.

    2017-10-01

    The X-ray bright, hot gas in the potential well of a galaxy cluster enables systematic X-ray studies of samples of galaxy clusters to constrain cosmological parameters. HIFLUGCS consists of the 64 X-ray brightest galaxy clusters in the Universe, building up a local sample. Here, we utilize this sample to determine, for the first time, individual hydrostatic mass estimates for all the clusters of the sample and, by making use of the completeness of the sample, we quantify constraints on the two interesting cosmological parameters, Ωm and σ8. We apply our total hydrostatic and gas mass estimates from the X-ray analysis to a Bayesian cosmological likelihood analysis and leave several parameters free to be constrained. We find Ωm = 0.30 ± 0.01 and σ8 = 0.79 ± 0.03 (statistical uncertainties, 68 per cent credibility level) using our default analysis strategy combining both a mass function analysis and the gas mass fraction results. The main sources of biases that we correct here are (1) the influence of galaxy groups (incompleteness in parent samples and differing behaviour of the Lx-M relation), (2) the hydrostatic mass bias, (3) the extrapolation of the total mass (comparing various methods), (4) the theoretical halo mass function and (5) other physical effects (non-negligible neutrino mass). We find that galaxy groups introduce a strong bias, since their number density seems to be over predicted by the halo mass function. On the other hand, incorporating baryonic effects does not result in a significant change in the constraints. The total (uncorrected) systematic uncertainties (∼20 per cent) clearly dominate the statistical uncertainties on cosmological parameters for our sample.

  17. Measuring Galaxy Clustering and the Evolution of [C II] Mean Intensity with Far-IR Line Intensity Mapping during 0.5 < z < 1.5

    Science.gov (United States)

    Uzgil, Bade; Aguirre, James E.; Bradford, Charles; Lidz, Adam

    2016-01-01

    Infrared fine-structure emission lines from trace metals are powerful diagnostics of the interstellar medium in galaxies. We explore the possibility of studying the redshifted far-IR fine-structure line emission using the three-dimensional (3D) power spectra obtained with an imaging spectrometer. The intensity mapping approach measures the spatio-spectral fluctuations due to line emission from all galaxies, including those below the individual detection threshold. The technique provides 3D measurements of galaxy clustering and moments of the galaxy luminosity function. Furthermore, the linear portion of the power spectrum can be used to measure the total line emission intensity including all sources through cosmic time with redshift information naturally encoded. As a case study, we consider measurement of [C II] autocorrelation in the 0.5 < z < 1.5 epoch, where interloper lines are minimized, using far-IR/submillimeter balloon-borne and future space-borne instruments with moderate and high sensitivity, respectively. In this context, we compare the intensity mapping approach to blind galaxy surveys based on individual detections. We find that intensity mapping is nearly always the best way to obtain the total line emission because blind, wide-field galaxy surveys lack sufficient depth and deep pencil beams do not observe enough galaxies in the requisite luminosity and redshift bins. Also, intensity mapping is often the most efficient way to measure the power spectrum shape, depending on the details of the luminosity function and the telescope aperture.

  18. Metal-rich absorbers at high redshifts: abundance patterns

    CERN Document Server

    Levshakov, S A; Molaro, P; Reimers, D; Hou, J L

    2009-01-01

    (Abbreviated) From six spectra of high-z QSOs, we select eleven metal-rich, Z>=Z_solar, and optically-thin to the ionizing radiation, N(HI)0, which supposes that the nitrogen enrichment occurs irregularly. In some cases, the lines of MgII 2796, 2803 appear to be shifted, probably as a result of an enhanced content of heavy isotopes 25Mg and 26Mg in the absorbing gas relative to the solar isotopic composition. Seven absorbers are characterized by low mean ionization parameter U, log U2 whereas all others are found at z ~= 1.8. Comparing the space number density of metal-rich absorbers with the comoving density of star-forming galaxies at z ~= 2, we estimate that the circumgalactic volume of each galaxy is populated by 10^7 - 10^8 such absorbers with total mass <=1/100th of the stellar galactic mass. Possible effects of high metal content on the peak values of star-forming and AGN activities at z~2 are discussed.

  19. SDSS-II Supernova survey. An analysis of the largest sample of type IA supernovae and correlations with host-galaxy spectral properties

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Rachel C.; D’Andrea, Chris B.; Gupta, Ravi R.; Sako, Masao; Fischer, John A.; Kessler, Rick; Jha, Saurabh W.; March, Marisa C.; Scolnic, Daniel M.; Fischer, Johanna-Laina; Campbell, Heather; Nichol, Robert C.; Olmstead, Matthew D.; Richmond, Michael; Schneider, Donald P.; Smith, Mathew

    2016-04-20

    Using the largest single-survey sample of Type Ia supernovae (SNe Ia) to date, we study the relationship between properties of SNe Ia and those of their host galaxies, focusing primarily on correlations with Hubble residuals (HR). Our sample consists of 345 photometrically-classified or spectroscopicallyconfirmed SNe Ia discovered as part of the SDSS-II Supernova Survey (SDSS-SNS). This analysis utilizes host-galaxy spectroscopy obtained during the SDSS-I/II spectroscopic survey and from an ancillary program on the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) that obtained spectra for nearly all host galaxies of SDSS-II SN candidates. In addition, we use photometric hostgalaxy properties from the SDSS-SNS data release (Sako et al. 2014) such as host stellar mass and star-formation rate. We confirm the well-known relation between HR and host-galaxy mass and find a 3.6σ significance of a non-zero linear slope. We also recover correlations between HR and hostgalaxy gas-phase metallicity and specific star-formation rate as they are reported in the literature. With our large dataset, we examine correlations between HR and multiple host-galaxy properties simultaneously and find no evidence of a significant correlation. We also independently analyze our spectroscopically-confirmed and photometrically-classified SNe Ia and comment on the significance of similar combined datasets for future surveys.

  20. HIGH-LYING OH ABSORPTION, [C II] DEFICITS, AND EXTREME L {sub FIR}/M {sub H2} RATIOS IN GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    González-Alfonso, E.; Blasco, A. [Universidad de Alcalá, Departamento de Física y Matemáticas, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Fischer, J. [Naval Research Laboratory, Remote Sensing Division, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Sturm, E.; Graciá-Carpio, J.; Lutz, D.; Poglitsch, A.; Contursi, A. [Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstraße 1, D-85748 Garching (Germany); Veilleux, S.; Meléndez, M. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Aalto, S.; Falstad, N. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden); Spoon, H. W. W. [Cornell University, Astronomy Department, Ithaca, NY 14853 (United States); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Henkel, C. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121, Bonn (Germany); Verma, A. [University of Oxford, Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Spaans, M. [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands); Smith, H. A.; Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hailey-Dunsheath, S. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); and others

    2015-02-10

    Herschel/PACS observations of 29 local (ultra)luminous infrared galaxies, including both starburst and active galactic nucleus (AGN) dominated sources as diagnosed in the mid-infrared/optical, show that the equivalent width of the absorbing OH 65 μm Π{sub 3/2} J = 9/2-7/2 line (W {sub eq}(OH65)) with lower level energy E {sub low} ≈ 300 K, is anticorrelated with the [C II]158 μm line to far-infrared luminosity ratio, and correlated with the far-infrared luminosity per unit gas mass and with the 60-to-100 μm far-infrared color. While all sources are in the active L {sub IR}/M {sub H2} > 50L {sub ☉}/M {sub ☉} mode as derived from previous CO line studies, the OH65 absorption shows a bimodal distribution with a discontinuity at L {sub FIR}/M {sub H2} ≈ 100 L {sub ☉}/M {sub ☉}. In the most buried sources, OH65 probes material partially responsible for the silicate 9.7 μm absorption. Combined with observations of the OH 71 μm Π{sub 1/2} J = 7/2-5/2 doublet (E {sub low} ≈ 415 K), radiative transfer models characterized by the equivalent dust temperature, T {sub dust}, and the continuum optical depth at 100 μm, τ{sub 100}, indicate that strong [C II]158 μm deficits are associated with far-IR thick (τ{sub 100} ≳ 0.7, N {sub H} ≳ 10{sup 24} cm{sup –2}), warm (T {sub dust} ≳ 60 K) structures where the OH 65 μm absorption is produced, most likely in circumnuclear disks/tori/cocoons. With their high L {sub FIR}/M {sub H2} ratios and columns, the presence of these structures is expected to give rise to strong [C II] deficits. W {sub eq}(OH65) probes the fraction of infrared luminosity arising from these compact/warm environments, which is ≳ 30%-50% in sources with high W {sub eq}(OH65). Sources with high W {sub eq}(OH65) have surface densities of both L {sub IR} and M {sub H2} higher than inferred from the half-light (CO or UV/optical) radius, tracing coherent structures that represent the most buried/active stage of (circum)nuclear starburst

  1. On the Observed W_MgII--L_[OII] Correlation in SDSS QSO Spectra

    CERN Document Server

    López, Gilberto

    2011-01-01

    This paper investigates the effect of differential aperture loss with SDSS fibers and examines whether such selection bias would result in the observed correlation between rest-frame absorption equivalent width of MgII absorbers, Wr(2796), and mean associated [OII] luminosity, L_[OII], in SDSS QSO spectra. We demonstrate based on a Monte Carlo simulation that the observed Wr(2796) vs. L_[OII] correlation of MgII absorbers can be well-reproduced, if all galaxies found in deep surveys possess extended MgII halos and if the extent of MgII halos scales proportionally with galaxy mass as shown in previous studies. The observed correlation can be explained by a combination of (1) the known Wr(2796) vs. rho anti-correlation in galaxy and MgII absorber pairs and (2) an increasing aperture loss in the 3" diameter SDSS fiber for galaxies at larger rho. Galaxies at larger projected distances produce on average weaker MgII absorbers and weaker (or zero) L_[OII] in SDSS QSO spectra. We show that such correlation diminishe...

  2. Uncovering Additional Clues to Galaxy Evolution. II. The Environmental Impact of the Virgo Cluster on the Evolution of Dwarf Irregular Galaxies

    CERN Document Server

    Lee, H; Richer, M G; Lee, Henry; Call, Marshall L. Mc; Richer, Michael G.

    2003-01-01

    The impact of the cluster environment on the evolution of dwarf galaxies is investigated by comparing the properties of a sample of dwarf irregulars (dIs) in the Virgo Cluster with a control sample of nearby ("field") dIs having oxygen abundances derived from [O III]4363 measurements and measured distances from resolved stellar constituents. Spectroscopic data are obtained for H II regions in 11 Virgo dIs distributed in the central and outer regions of the cluster. To ensure that oxygen abundances are derived in a homogeneous manner, oxygen abundances for field and Virgo dIs are computed using the bright-line method and compared with abundances directly obtained from [O III]4363, where available. They are found to agree to within about 0.2 dex with no systematic offset. At a given optical luminosity, there is no systematic difference in oxygen abundance between the sample of Virgo dIs and the sample of nearby dIs. However, five of the eleven Virgo dIs exhibit much lower baryonic gas fractions than field dIs a...

  3. GMASS Ultradeep Spectroscopy of Galaxies at 1.4II. Superdense passive galaxies: how did they form and evolve ?

    CERN Document Server

    Cimatti, A; Pozzetti, L; Kurk, J; Mignoli, M; Renzini, A; Daddi, E; Bolzonella, M; Brusa, M; Rodighiero, G; Dickinson, M; Franceschini, A; Zamorani, G; Berta, S; Rosati, P; Halliday, C

    2008-01-01

    We combine ultradeep optical spectroscopy from the GMASS project ("Galaxy Mass Assembly ultradeep Spectroscopic Survey") with GOODS multi-band photometry and HST imaging to study a sample of passive galaxiesat 1.392. These galaxies have morphologies that are predominantly compact and spheroidal.However, their sizes (R_e 1, and absent if R_e2. The results are compared with theoretical models and the main implications discussed in the framework of massive galaxy formation and evolution.

  4. Fundamental properties of Fanaroff-Riley II radio galaxies investigated via Monte Carlo simulations

    CERN Document Server

    Kapińska, Anna D; Kaiser, Christian R

    2012-01-01

    [Abridged] Radio galaxies and quasars are among the largest and most powerful single objects known and are believed to have had a significant impact on the evolving Universe and its large scale structure. We explore the intrinsic and extrinsic properties of the population of FRII objects (kinetic luminosities, lifetimes, and the central densities of their environments). In particular, the radio and kinetic luminosity functions of FRIIs are investigated using the complete, flux limited radio catalogues of 3CRR and Best et al. We construct multidimensional Monte Carlo simulations using semi-analytical models of FRII radio source growth to create artificial samples of radio galaxies. Unlike previous studies, we compare radio luminosity functions found with both the observed and simulated data to explore the fundamental source parameters. We allow the source physical properties to co-evolve with redshift, and we find that all the investigated parameters most likely undergo cosmological evolution. Strikingly, we f...

  5. SLUG - Stochastically Lighting Up Galaxies. II: Quantifying the Effects of Stochasticity on Star Formation Rate Indicators

    CERN Document Server

    da Silva, Robert L; Krumholz, Mark R

    2014-01-01

    The integrated light of a stellar population, measured through photometric filters that are sensitive to the presence of young stars, is often used to infer the star formation rate (SFR) for that population. However, these techniques rely on an assumption that star formation is a continuous process, whereas in reality stars form in discrete spatially- and temporally-correlated structures. This discreteness causes the light output to undergo significant time-dependent fluctuations, which, if not accounted for, introduce errors and biases in the inferred SFRs. We use SLUG (a code that Stochastically Lights Up Galaxies) to simulate galaxies undergoing stochastic star formation. We then use these simulations to present a quantitative analysis of these effects and provide tools for calculating probability distribution functions of SFRs given a set of observations. We show that, depending on the SFR tracer used, stochastic fluctuations can produce non-trivial errors at SFRs as high as 1 Msun/yr, and we suggest meth...

  6. The AGORA High-Resolution Galaxy Simulations Comparison Project. II: Isolated Disk Test

    CERN Document Server

    Kim, Ji-hoon; Teyssier, Romain; Butler, Michael J; Ceverino, Daniel; Choi, Jun-Hwan; Feldmann, Robert; Keller, Ben W; Lupi, Alessandro; Quinn, Thomas; Revaz, Yves; Wallace, Spencer; Gnedin, Nickolay Y; Leitner, Samuel N; Shen, Sijing; Smith, Britton D; Thompson, Robert; Turk, Matthew J; Abel, Tom; Arraki, Kenza S; Benincasa, Samantha M; Chakrabarti, Sukanya; DeGraf, Colin; Dekel, Avishai; Goldbaum, Nathan J; Hopkins, Philip F; Hummels, Cameron B; Klypin, Anatoly; Li, Hui; Madau, Piero; Mandelker, Nir; Mayer, Lucio; Nagamine, Kentaro; Nickerson, Sarah; O'Shea, Brian W; Primack, Joel R; Roca-Fàbrega, Santi; Semenov, Vadim; Shimizu, Ikkoh; Simpson, Christine M; Todoroki, Keita; Wadsley, James W; Wise, John H

    2016-01-01

    Using an isolated Milky Way-mass galaxy simulation, we compare results from 9 state-of-the-art gravito-hydrodynamics codes widely used in the numerical community. We utilize the infrastructure we have built for the AGORA High-resolution Galaxy Simulations Comparison Project. This includes the common disk initial conditions, common physics models (e.g., radiative cooling and UV background by the standardized package Grackle) and common analysis toolkit yt, all of which are publicly available. Subgrid physics models such as Jeans pressure floor, star formation, supernova feedback energy, and metal production are carefully constrained across code platforms. With numerical accuracy that resolves the disk scale height, we find that the codes overall agree well with one another in many dimensions including: gas and stellar surface densities, rotation curves, velocity dispersions, density and temperature distribution functions, disk vertical heights, stellar clumps, star formation rates, and Kennicutt-Schmidt relati...

  7. High resolution spectroscopy of the BCD galaxy Haro 15: II. Chemodynamics

    CERN Document Server

    Hagele, Guillermo F; Bosch, Guillermo; Diaz, Angeles I; Morrell, Nidia

    2012-01-01

    We present a detailed study of the physical properties of the nebular material in four star-forming knots of the blue compact dwarf galaxy Haro 15. Using long-slit and echelle spectroscopy obtained at Las Campanas Observatory, we study the physical conditions (electron density and temperatures), ionic and total chemical abundances of several atoms, reddening and ionization structure, for the global flux and for the different kinematical components. The latter was derived by comparing the oxygen and sulphur ionic ratios to their corresponding observed emission line ratios (the $\\eta$ and $\\eta$' plots) in different regions of the galaxy. Applying the direct method or empirical relationships for abundance determination, we perform a comparative analysis between these regions. The similarities found in the ionization structure of the different kinematical components implies that the effective temperatures of the ionizing radiation fields are very similar in spite of some small differences in the ionization state...

  8. Disentangling the ISM phases of the dwarf galaxy NGC 4214 using [C ii] SOFIA/GREAT observations

    Science.gov (United States)

    Fahrion, K.; Cormier, D.; Bigiel, F.; Hony, S.; Abel, N. P.; Cigan, P.; Csengeri, T.; Graf, U. U.; Lebouteiller, V.; Madden, S. C.; Wu, R.; Young, L.

    2017-02-01

    Context. The [C ii] 158 μm fine structure line is one of the dominant cooling lines in the interstellar medium (ISM) and is an important tracer of star formation. Recent velocity-resolved studies with Herschel/HIFI and SOFIA/GREAT showed that the [C ii] line can constrain the properties of the ISM phases in star-forming regions. The [C ii] line as a tracer of star formation is particularly important in low-metallicity environments where CO emission is weak because of the presence of large amounts of CO-dark gas. Aims: The nearby irregular dwarf galaxy NGC 4214 offers an excellent opportunity to study an actively star-forming ISM at low metallicity. We analyzed the spectrally resolved [C ii] line profiles in three distinct regions at different evolutionary stages of NGC 4214 with respect to ancillary H i and CO data in order to study the origin of the [C ii] line. Methods: We used SOFIA/GREAT [C ii] 158 μm observations, H i data from THINGS, and CO(2 → 1) data from HERACLES to decompose the spectrally resolved [C ii] line profiles into components associated with neutral atomic and molecular gas. We use this decomposition to infer gas masses traced by [C ii] under different ISM conditions. Results: Averaged over all regions, we associate about 46% of the [C ii] emission with the H i emission. However, we can assign only 9% of the total [C ii] emission to the cold neutral medium (CNM). We found that about 79% of the total molecular hydrogen mass is not traced by CO emission. Conclusions: On average, the fraction of CO-dark gas dominates the molecular gas mass budget. The fraction seems to depend on the evolutionary stage of the regions: it is highest in the region covering a super star cluster in NGC 4214, while it is lower in a more compact, more metal-rich region. Reduced SOFIA/GREAT data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A9

  9. Hubble Space Telescope Observations of Sub-Damped Lyman-alpha Absorbers at z < 0.5, and Implications for Galaxy Chemical Evolution

    CERN Document Server

    Som, Debopam; Meiring, Joseph; York, Donald G; Péroux, Celine; Lauroesch, James T; Aller, Monique C; Khare, Pushpa

    2015-01-01

    We report observations of four sub-damped Lyman-alpha (sub-DLA) quasar absorbers at z<0.5 obtained with the Hubble Space Telescope Cosmic Origins Spectrograph. We measure the available neutrals or ions of C, N, O, Si, P, S, Ar, Mn, Fe, and/or Ni. Our data have doubled the sub-DLA metallicity samples at z<0.5 and improved constraints on sub-DLA chemical evolution. All four of our sub-DLAs are consistent with near-solar or super-solar metallicities and relatively modest ionization corrections; observations of more lines and detailed modeling will help to verify this. Combining our data with measurements from the literature, we confirm previous suggestions that the N(HI)-weighted mean metallicity of sub-DLAs exceeds that of DLAs at all redshifts studied, even after making ionization corrections for sub-DLAs. The absorber toward PHL 1598 shows significant dust depletion. The absorbers toward PHL 1226 and PKS 0439-433 show the S/P ratio consistent with solar, i.e., they lack a profound odd-even effect. The a...

  10. The variation in molecular gas depletion time: II the impact of galaxy internal structures

    CERN Document Server

    Huang, Mei-Ling

    2014-01-01

    We use a data set of nearby galaxies drawn from the HERACLES, ATLAS3D, and COLD GASS surveys to study variations in molecular gas depletion time (Tdep) in galaxy structures such as bulges, grand-design spiral arms, bars and rings. Molecular gas is traced by CO line emission and star formation rate (SFR) is derived using the combination of far-ultraviolet and mid-infrared (MIR) data. The contribution of old stars to MIR emission for the ATLAS3D sample is corrected using 2MASS K-band images. We apply a two-dimensional image decomposition algorithm to decompose galaxies into bulges and discs. Spiral arms, bars and rings are identified in the residual maps, and molecular gas depletion times are derived on a square grid of 1 kpc^2 size. In previous work, we showed that Tdep correlates strongly with specific star formation rate (sSFR). We now find that at a given sSFR, the bulge has shorter Tdep than the disc. The shift to shorter depletion times is most pronounced in the inner bulge (R < 0.1Re). Grids from gala...

  11. Radial distribution of stars, gas and dust in SINGS galaxies. II. Derived dust properties

    CERN Document Server

    Muñoz-Mateos, J C; Boissier, S; Zamorano, J; Dale, D A; Pérez-González, P G; Gallego, J; Madore, B F; Bendo, G; Thornley, M D; Draine, B T; Boselli, A; Buat, V; Calzetti, D; Moustakas, J; Kennicutt, R C; 10.1088/0004-637X/701/2/1965

    2009-01-01

    We present a detailed analysis of the radial distribution of dust properties in the SINGS sample, performed on a set of UV, IR and HI surface brightness profiles, combined with published molecular gas profiles and metallicity gradients. The internal extinction, derived from the TIR-to-FUV luminosity ratio, decreases with radius, and is larger in Sb-Sbc galaxies. The TIR-to-FUV ratio correlates with the UV spectral slope beta, following a sequence shifted to redder UV colors with respect to that of starbursts. The star formation history (SFH) is identified as the main driver of this departure. We have also derived radial profiles of the total dust mass surface density, the fraction of the dust mass contributed by PAHs, the fraction of the dust mass heated by very intense starlight and the intensity of the radiation field heating the grains. The dust profiles are exponential, their radial scale-length being constant from Sb to Sd galaxies (only ~10% larger than the stellar scale-length). Many S0/a-Sab galaxies ...

  12. Cosmic reionization on computers. II. Reionization history and its back-reaction on early galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Gnedin, Nickolay Y. [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kaurov, Alexander A., E-mail: gnedin@fnal.gov, E-mail: kaurov@uchicago.edu [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States)

    2014-09-20

    We compare the results from several sets of cosmological simulations of cosmic reionization, produced under the Cosmic Reionization On Computers project, with existing observational data on the high-redshift Lyα forest and the abundance of Lyα emitters. We find good consistency with the observational measurements and previous simulation work. By virtue of having several independent realizations for each set of numerical parameters, we are able to explore the effect of cosmic variance on observable quantities. One unexpected conclusion we are forced into is that cosmic variance is unusually large at z > 6, with both our simulations and, most likely, observational measurements still not fully converged for even such basic quantities as the average Gunn-Peterson optical depth or the volume-weighted neutral fraction. We also find that reionization has little effect on the early galaxies or on global cosmic star formation history, because galaxies whose gas content is affected by photoionization contain no molecular (i.e., star-forming) gas in the first place. In particular, measurements of the faint end of the galaxy luminosity function by the James Webb Space Telescope are unlikely to provide a useful constraint on reionization.

  13. The star formation histories of local group dwarf galaxies. II. Searching for signatures of reionization

    Energy Technology Data Exchange (ETDEWEB)

    Weisz, Daniel R. [Department of Astronomy, University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Skillman, Evan D. [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Holtzman, Jon [Department of Astronomy, New Mexico State University, Box 30001, 1320 Frenger Street, Las Cruces, NM 88003 (United States); Gilbert, Karoline M.; Dalcanton, Julianne J.; Williams, Benjamin F., E-mail: drw@ucsc.edu [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)

    2014-07-10

    We search for signatures of reionization in the star formation histories (SFHs) of 38 Local Group dwarf galaxies (10{sup 4} < M{sub *} < 10{sup 9} M{sub ☉}). The SFHs are derived from color-magnitude diagrams using archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. Only five quenched galaxies (And V, And VI, And XIII, Leo IV, and Hercules) are consistent with forming the bulk of their stars before reionization, when full uncertainties are considered. Observations of 13 of the predicted 'true fossils' identified by Bovill and Ricotti show that only two (Hercules and Leo IV) indicate star formation quenched by reionization. However, both are within the virial radius of the Milky Way and evidence of tidal disturbance complicates this interpretation. We argue that the late-time gas capture scenario posited by Ricotti for the low mass, gas-rich, and star-forming fossil candidate Leo T is observationally indistinguishable from simple gas retention. Given the ambiguity between environmental effects and reionization, the best reionization fossil candidates are quenched low mass field galaxies (e.g., KKR 25).

  14. RHAPSODY-G simulations II - Baryonic growth and metal enrichment in massive galaxy clusters

    CERN Document Server

    Martizzi, Davide; Wu, Hao-Yi; Evrard, August E; Teyssier, Romain; Wechsler, Risa H

    2015-01-01

    We study the evolution of the stellar component and the metallicity of both the intracluster medium and of stars in massive ($M_{\\rm vir}\\approx 6\\times 10^{14}$ M$_{\\odot}$) simulated galaxy clusters from the RHAPSODY-G suite in detail and compare them to observational results. The simulations were performed with the AMR code RAMSES and include the effect of AGN feedback at the sub-grid level. AGN feedback is required to produce realistic galaxy and cluster properties and plays a role in mixing material in the central regions and regulating star formation in the central galaxy. In our low resolution runs with fiducial stellar yields, we find that stellar and ICM metallicities are a factor of two lower than in observations, however they tend to converge to the observed values $\\sim 0.3$ Z$_{\\odot}$ as the resolution is increased. We find that cool core clusters exhibit steeper metallicity gradients than non-cool core clusters, in qualitative agreement with observations. We verify that the ICM metallicities me...

  15. Chandra Survey of Nearby Highly Inclined Disc Galaxies - II: Correlation Analysis of Galactic Coronal Properties

    CERN Document Server

    Li, Jiang-Tao

    2013-01-01

    X-ray observations provide a key tool for exploring the properties of galactic coronae and their formation processes. In an earlier paper, we have presented a Chandra data analysis of the coronae of 53 nearby highly-inclined disc galaxies. Here we study the correlation of the X-ray measurements with other galaxy properties and compare the results with those obtained for elliptical galaxies. A good correlation is present between the coronal luminosity Lx and the SFR. But we find a better correlation between Lx and the total SN mechanical energy input rate (ESN), including the expected contribution from core collapsed (CC) and Ia SNe. The X-ray radiation efficiency (eta=Lx/ESN) has a mean value of ~0.4% with an rms of ~0.5dex. eta further correlates with MTF/M* (MTF is the baryon mass measured from the rotation velocity and the Tully-Fisher relation, M* is the stellar mass measured from the K-band luminosity) and the CC SN rate surface density (FSN, in units of SN/yr/kpc^2), which can be characterized as: eta=0...

  16. A Test of Star Formation Laws in Disk Galaxies. II. Dependence on dynamical properties

    CERN Document Server

    Suwannajak, Chutipong; Leroy, Adam K

    2014-01-01

    We use observed radial profiles of mass surface densities of total, $\\Sigma_g$, & molecular, $\\Sigma_{\\rm H2}$, gas, rotation velocity & star formation rate (SFR) surface density, $\\Sigma_{\\rm sfr}$, of the molecular-rich ($\\Sigma_{\\rm H2}\\ge\\Sigma_{\\rm HI}/2$) regions of 16 nearby disk galaxies to test several star formation laws: a Kennicutt-Schmidt law, $\\Sigma_{\\rm sfr}=A_g\\Sigma_{g,2}^{1.5}$; a Constant Molecular law, $\\Sigma_{\\rm sfr}=A_{\\rm H2}\\Sigma_{\\rm H2,2}$; the turbulence-regulated laws of Krumholz & McKee (KM05) and Krumholz et al. (KMT09), a Gas-$\\Omega$ law, $\\Sigma_{\\rm sfr}=B_\\Omega\\Sigma_g\\Omega$; and a shear-driven GMC Collision law, $\\Sigma_{\\rm sfr}=B_{\\rm CC}\\Sigma_g\\Omega(1-0.7\\beta)$, where $\\beta\\equiv d {\\rm ln} v_{\\rm circ}/d {\\rm ln} r$. If allowed one free normalization parameter for each galaxy, these laws predict the SFR with rms errors of factors of 1.4 - 1.8. If a single normalization parameter is used by each law for the entire galaxy sample, then rms errors rang...

  17. HST Morphologies of z ~ 2 Dust-Obscured Galaxies II: Bump Sources

    CERN Document Server

    Bussmann, R S; Lotz, J; Armus, L; Brown, M J I; Desai, V; Eisenhardt, P; Higdon, J; Higdon, S; Jannuzi, B T; Floc'h, E Le; Melbourne, J; Soifer, B T; Weedman, D

    2011-01-01

    We present Hubble Space Telescope (HST) imaging of 22 ultra-luminous infrared galaxies (ULIRGs) at z~2 with extremely red R-[24] colors (called dust-obscured galaxies, or DOGs) which have a local maximum in their spectral energy distribution (SED) at rest-frame 1.6um associated with stellar emission. These sources, which we call "bump DOGs", have star-formation rates of 400-4000 Msun/yr and have redshifts derived from mid-IR spectra which show strong polycyclic aromatic hydrocarbon emission --- a sign of vigorous on-going star-formation. Using a uniform morphological analysis, we look for quantifiable differences between bump DOGs, power-law DOGs (Spitzer-selected ULIRGs with mid-IR SEDs dominated by a power-law and spectral features that are more typical of obscured active galactic nuclei than starbursts), sub-millimeter selected galaxies (SMGs), and other less-reddened ULIRGs from the Spitzer extragalactic First Look Survey (XFLS). Bump DOGs are larger than power-law DOGs (median Petrosian radius of 8.4 +/-...

  18. PRESENT-DAY DESCENDANTS OF z = 3 Ly{alpha}-EMITTING GALAXIES IN THE MILLENNIUM-II HALO MERGER TREES

    Energy Technology Data Exchange (ETDEWEB)

    Walker-Soler, Jean P.; Gawiser, Eric [Physics and Astronomy Department, Rutgers University, Piscataway, NJ 08854 (United States); Bond, Nicholas A. [Goddard Space Flight Center, Astrophysics Science Division, Observational Cosmology Laboratory, Greenbelt, MD 20771 (United States); Padilla, Nelson; Francke, Harold, E-mail: jpwalker@physics.rutgers.edu [Pontificia Universidad Catolica de Chile, Facultad de Fisica, Santiago (Chile)

    2012-06-20

    Using the Millennium-II Simulation dark matter sub-halo merger histories, we created mock catalogs of Ly{alpha}-emitting (LAE) galaxies at z = 3.1 to study the properties of their descendants. Several models were created by selecting the sub-halos to match the number density and typical dark matter mass determined from observations of these galaxies. We used mass-based and age-based selection criteria to study their effects on descendant populations at z {approx_equal} 2, 1, and 0. For the models that best represent LAEs at z = 3.1, the z = 0 descendants have a median dark matter halo mass of 10{sup 12.7} M{sub Sun }, with a wide scatter in masses (50% between 10{sup 11.8} and 10{sup 13.7} M{sub Sun }). Our study differentiated between central and satellite sub-halos and found that {approx}55% of z = 0 descendants are central sub-halos with M{sub Median} {approx} 10{sup 12}. This confirms that central z = 0 descendants of z = 3.1 LAEs have halo masses typical of L*-type galaxies. The satellite sub-halos reside in group/cluster environments with dark matter masses around 10{sup 14} M{sub Sun }. The median descendant mass is robust to various methods of age determination, but it could vary by a factor of five due to current observational uncertainties in the clustering of LAEs used to determine their typical z = 3.1 dark matter mass.

  19. Calcium H & K Induced by Galaxy Halos

    CERN Document Server

    Zhu, Guangtun

    2013-01-01

    We present a measurement of the mean density profile of Ca II gas around galaxies out to ~ 200 kpc, traced by Fraunhofer's H & K absorption lines. The measurement is based on cross-correlating the positions of about one million foreground galaxies at z ~ 0.1 and the flux decrements induced in the spectra of about 10^5 background quasars from the Sloan Digital Sky Survey. This technique allows us to trace the total amount of Ca II absorption induced by the circumgalactic medium, including absorbers too weak to be detected in individual spectra. We can statistically measure Ca II rest equivalent widths down to several mA, corresponding to column densities of about 5x10^10 cm^{-2}. We find that the Ca II column density distribution follows N ~ rp^{-1.4} and the mean Ca II mass in the halo within 200 kpc is ~ 5x10^3 Msolar, averaged over the foreground galaxy sample with median mass ~ 10^10.3 Msolar. This is about an order-of-magnitude larger than the Ca II mass in the interstellar medium of the Milky Way, su...

  20. Unveiling the Monsters: Characterization of Ultra-massive Galaxies in the Early Universe with IRAC Mapping of the NMBS-II/CFHTLS Fields

    Science.gov (United States)

    Marchesini, Danilo

    Observations of massive galaxies and their evolution with cosmic time place strong constraints on the physical processes of galaxy formation. Although substantial data have been collected on galaxies with masses log(Mstar/Msun)~11.2 out to z~4-5 from the recent myriad of ground-based near-infrared (NIR) surveys, very little is known about the evolution of the most massive (log(Mstar/Msun)>11.4) galaxies in the universe. At the tip of the Schechter function, their space density is estimated to be 30x lower than log (Mstar/Msun)=11 galaxies and hence only a few have been found, even in the widest-field surveys. We recently undertook the NMBS-II survey, a wide-field NIR medium-band survey designed to accurately characterize the stellar mass function, number density, stellar population and clustering properties of the most massive galaxies out to z=3. The NMBSII uses a set of five medium-bandwidth NIR filters to provide precise photometric redshifts and well-sampled spectral energy distributions (SEDs) of galaxies at z>1.5. The primary survey fields of the NMBS-II are the CFHTLS-deep fields; however, presently only 60% of these fields have IRAC coverage. The IRAC data are essential for accurately measuring photometric redshifts and stellar masses of the high-redshift population. IRAC data are also critical for separating the red quiescent from the red, dusty star-forming galaxies at z>0.8. In Cycle 10 (12/2013-10/2014), the PI Marchesini was awarded 22 hours of Spitzer time to complete the IRAC coverage of the NMBS-II fields, for a total area of 5.4 sq. deg. over 7 independent lines of sight. This proposal describes a program consisting of three main components. First, the newly acquired IRAC data at 3.6 and 4.5 micron awarded to the PI to complete the IRAC coverage of the NMBS-II fields will be reduced. Second, the addition of the Spitzer-IRAC and MIPS photometry to the NMBS-II K-selected catalogs will be completed. Third, a unique sample of ~300 ultra

  1. THE {gamma}-RAY EMISSION REGION IN THE FANAROFF-RILEY II RADIO GALAXY 3C 111

    Energy Technology Data Exchange (ETDEWEB)

    Grandi, P.; Torresi, E. [Istituto Nazionale di Astrofisica-IASFBO, Via Gobetti 101, I-40129, Bologna (Italy); Stanghellini, C., E-mail: grandi@iasfbo.inaf.it, E-mail: torresi@iasfbo.inaf.it, E-mail: cstan@ira.inaf.it [Istituto Nazionale di Astrofisica-IRA, Via Gobetti 101, I-40129, Bologna (Italy)

    2012-05-20

    The broad-line radio galaxy 3C 111, characterized by a Fanaroff-Riley II (FRII) radio morphology, is one of the sources of the misaligned active galactic nucleus sample, consisting of radio galaxies and steep spectrum radio quasars, recently detected by the Fermi Large Area Telescope (LAT). Our analysis of the 24 month {gamma}-ray light curve shows that 3C 111 was only occasionally detected at high energies. It was bright at the end of 2008 and faint, below the Fermi-LAT sensitivity threshold, for the rest of the time. A multifrequency campaign of 3C 111, ongoing in the same period, revealed an increase of the millimeter, optical, and X-ray fluxes in 2008 September-November, interpreted by Chatterjee et al. as due to the passage of a superluminal knot through the jet core. The temporal coincidence of the millimeter-optical-X-ray outburst with the GeV activity suggests a cospatiality of the events, allowing, for the first time, the localization of the {gamma}-ray dissipative zone in an FRII jet. We argue that the GeV photons of 3C 111 are produced in a compact region confined within 0.1 pc and at a distance of about 0.3 pc from the black hole.

  2. Morphologies of ~190,000 Galaxies at z=0-10 Revealed with HST Legacy Data II. Evolution of Clumpy Galaxies

    CERN Document Server

    Shibuya, Takatoshi; Kubo, Mariko; Harikane, Yuichi

    2015-01-01

    We investigate evolution of clumpy galaxies with the Hubble Space Telescope (HST) samples of ~190,000 photo-z and Lyman break galaxies at z~0-8. We detect clumpy galaxies with off-center clumps in a self-consistent algorithm that is well tested with previous study results, and measure the number fraction of clumpy galaxies at the rest-frame UV, f_clumpy^UV. We identify an evolutionary trend of f_clumpy^UV over z~0-8 for the first time: f_clumpy^UV increases from z~8 to z~1-3 and subsequently decreases from z~1 to z~0, which follows the trend of Madau-Lilly plot. A low average Sersic index of n~1 is found in the underlining components of our clumpy galaxies at z~0-2, indicating that typical clumpy galaxies have disk-like surface brightness profiles. Our f_clumpy^UV values correlate with physical quantities related to star formation activities for star-forming galaxies at z~0-7. We find that clump colors tend to be red at a small galactocentric distance for massive galaxies with log(M_*/M_sun)>~11. All of these...

  3. Star formation and the interstellar medium in low surface brightness galaxies - II. Deep CO observations of low surface brightness disk galaxies

    NARCIS (Netherlands)

    de Blok, WJG; van der Hulst, JM

    1998-01-01

    We present deep, pointed (CO)-C-12(J = 2 - 1) observations of three late-type LSB galaxies. The beam-size was small enough that we could probe different environments (HI maximum, HI mininum, star forming region) in these galaxies. No CO was found at any of the positions observed. We argue that the i

  4. The Dragonfly Galaxy. II. ALMA unveils a triple merger and gas exchange in a hyper-luminous radio galaxy at z = 2

    NARCIS (Netherlands)

    Emonts, B. H. C.; De Breuck, C.; Lehnert, M. D.; Vernet, J.; Gullberg, B.; Villar-Martín, M.; Nesvadba, N.; Drouart, G.; Ivison, R.; Seymour, N.; Wylezalek, D.; Barthel, P.

    2015-01-01

    The Dragonfly Galaxy (MRC 0152-209), at redshift z ~ 2, is one of the most vigorously star-forming radio galaxies in the Universe. What triggered its activity? We present ALMA Cycle 2 observations of cold molecular CO(6-5) gas and dust, which reveal that this is likely a gas-rich triple merger. It c

  5. A new sample of X-ray selected narrow emission-line galaxies. II. Looking for True Seyfert 2

    CERN Document Server

    Pons, Estelle

    2016-01-01

    A sample of X-ray and optically selected narrow emission-line galaxies (769 sources) from the 3XMM catalogue cross-correlated with SDSS (DR9) catalogue has been studied. Narrow-emission line active galactic nuclei (AGN; type-2) have been selected on the basis of their emission line ratios and/or X-ray luminosity. We have looked for X-ray unobscured type-2 AGN. As X-ray spectra were not available for our whole sample, we have checked the reliability of using the X-ray hardness ratio (HR) as a probe of the level of obscuration and we found a very good agreement with full spectral fitting results, with only 2% of the sources with apparently unobscured HR turning out to have an obscured spectrum. Despite the fact that type-2 AGN are supposed to be absorbed based on the Unified Model, about 60% of them show no sign or very low level of X-ray obscuration. After subtraction of contaminants to the sample, that is Narrow-Line Seyfert 1 and Compton-thick AGN, the fraction of unobscured Sy2 drops to 47%. For these sourc...

  6. Galaxy Clusters in the Line of Sight to Background Quasars - III Multi-Object Spectroscopy

    CERN Document Server

    Andrews, H; Lopez, S; Lira, P; Padilla, N; Gilbank, D G; Lacerna, I; Maureira, M J; Ellingson, E; Gladders, M D; Yee, H K C

    2013-01-01

    We present Gemini/GMOS-S multi-object spectroscopy of 31 galaxy cluster candidates at redshifts between 0.2 and 1.0 and centered on QSO sight-lines taken from Lopez et al. (2008). The targets were selected based on the presence of a intervening MgII absorption system at a similar redshift to that of a galaxy cluster candidate lying at a projected distance < 2 h^{-1}Mpc from the QSO sight-line (a 'photometric-hit'). The absorption systems span rest-frame equivalent widths between 0.015 and 2.028 angstroms. Our aim was 3-fold: 1) identify the absorbing galaxies and determine their impact parameters, 2) confirm the galaxy cluster candidates in the vicinity of each quasar sightline, and 3) determine whether the absorbing galaxies reside in galaxy clusters. Our main findings are: 1) the identification of 10 out of 24 absorbing galaxies with redshifts up to 1.0955. 2) The spectroscopic confirmation of 20 out of 31 cluster/group candidates, with most of the confirmed clusters/groups at z < 0.7. 3) Following fr...

  7. The interstellar medium in Andromeda's dwarf spheroidal galaxies - II. Multiphase gas content and ISM conditions

    Science.gov (United States)

    De Looze, Ilse; Baes, Maarten; Cormier, Diane; Kaneko, Hiroyuki; Kuno, Nario; Young, Lisa; Bendo, George J.; Boquien, Médéric; Fritz, Jacopo; Gentile, Gianfranco; Kennicutt, Robert C.; Madden, Suzanne C.; Smith, Matthew W. L.; Wilson, Christine D.

    2017-03-01

    We make an inventory of the interstellar medium material in three low-metallicity dwarf spheroidal galaxies of the Local Group (NGC 147, NGC 185 and NGC 205). Ancillary H I, CO, Spitzer Infrared Spectrograph spectra, Hα and X-ray observations are combined to trace the atomic, cold and warm molecular, ionized and hot gas phases. We present new Nobeyama CO(1-0) observations and Herschel SPIRE FTS [C I] observations of NGC 205 to revise its molecular gas content. We derive total gas masses of Mg = 1.9-5.5 × 105 M⊙ for NGC 185 and Mg = 8.6-25.0 × 105 M⊙ for NGC 205. Non-detections combine to an upper limit on the gas mass of Mg ≤ 0.3-2.2 × 105 M⊙ for NGC 147. The observed gas reservoirs are significantly lower compared to the expected gas masses based on a simple closed-box model that accounts for the gas mass returned by planetary nebulae and supernovae. The gas-to-dust mass ratios GDR ∼ 37-107 and 48-139 are also considerably lower compared to the expected GDR ∼ 370 and 520 for the low metal abundances in NGC 185 (0.36 Z⊙) and NGC 205 (0.25 Z⊙), respectively. To simultaneously account for the gas deficiency and low gas-to-dust ratios, we require an efficient removal of a large gas fraction and a longer dust survival time (∼1.6 Gyr). We believe that efficient galactic winds (combined with heating of gas to sufficiently high temperatures in order for it to escape from the galaxy) and/or environmental interactions with neighbouring galaxies are responsible for the gas removal from NGC 147, NGC 185 and NGC 205.

  8. The AGORA High-resolution Galaxy Simulations Comparison Project. II. Isolated Disk Test

    Science.gov (United States)

    Kim, Ji-hoon; Agertz, Oscar; Teyssier, Romain; Butler, Michael J.; Ceverino, Daniel; Choi, Jun-Hwan; Feldmann, Robert; Keller, Ben W.; Lupi, Alessandro; Quinn, Thomas; Revaz, Yves; Wallace, Spencer; Gnedin, Nickolay Y.; Leitner, Samuel N.; Shen, Sijing; Smith, Britton D.; Thompson, Robert; Turk, Matthew J.; Abel, Tom; Arraki, Kenza S.; Benincasa, Samantha M.; Chakrabarti, Sukanya; DeGraf, Colin; Dekel, Avishai; Goldbaum, Nathan J.; Hopkins, Philip F.; Hummels, Cameron B.; Klypin, Anatoly; Li, Hui; Madau, Piero; Mandelker, Nir; Mayer, Lucio; Nagamine, Kentaro; Nickerson, Sarah; O'Shea, Brian W.; Primack, Joel R.; Roca-Fàbrega, Santi; Semenov, Vadim; Shimizu, Ikkoh; Simpson, Christine M.; Todoroki, Keita; Wadsley, James W.; Wise, John H.; AGORA Collaboration

    2016-12-01

    Using an isolated Milky Way-mass galaxy simulation, we compare results from nine state-of-the-art gravito-hydrodynamics codes widely used in the numerical community. We utilize the infrastructure we have built for the AGORA High-resolution Galaxy Simulations Comparison Project. This includes the common disk initial conditions, common physics models (e.g., radiative cooling and UV background by the standardized package Grackle) and common analysis toolkit yt, all of which are publicly available. Subgrid physics models such as Jeans pressure floor, star formation, supernova feedback energy, and metal production are carefully constrained across code platforms. With numerical accuracy that resolves the disk scale height, we find that the codes overall agree well with one another in many dimensions including: gas and stellar surface densities, rotation curves, velocity dispersions, density and temperature distribution functions, disk vertical heights, stellar clumps, star formation rates, and Kennicutt-Schmidt relations. Quantities such as velocity dispersions are very robust (agreement within a few tens of percent at all radii) while measures like newly formed stellar clump mass functions show more significant variation (difference by up to a factor of ˜3). Systematic differences exist, for example, between mesh-based and particle-based codes in the low-density region, and between more diffusive and less diffusive schemes in the high-density tail of the density distribution. Yet intrinsic code differences are generally small compared to the variations in numerical implementations of the common subgrid physics such as supernova feedback. Our experiment reassures that, if adequately designed in accordance with our proposed common parameters, results of a modern high-resolution galaxy formation simulation are more sensitive to input physics than to intrinsic differences in numerical schemes.

  9. The MUSIC of galaxy clusters - II. X-ray global properties and scaling relations

    Science.gov (United States)

    Biffi, V.; Sembolini, F.; De Petris, M.; Valdarnini, R.; Yepes, G.; Gottlöber, S.

    2014-03-01

    We present the X-ray properties and scaling relations of a large sample of clusters extracted from the Marenostrum MUltidark SImulations of galaxy Clusters (MUSIC) data set. We focus on a sub-sample of 179 clusters at redshift z ˜ 0.11, with 3.2 × 1014 h-1 M⊙ MUSIC clusters reasonably resemble the self-similar prediction, especially for correlations involving TX. The observational approach also allows for a more direct comparison with real clusters, from which we find deviations mainly due to the physical description of the ICM, affecting TX and, particularly, LX.

  10. 三星GALAXY S III采用康宁玻璃Gorilla II

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    康宁公司5月30日宣布,康宁公司推出的被普遍接受的保护玻璃,即第二代康宁 Gorilla 玻璃,已经被三星最新的GALAXY S III智能手机所采用。这种改进版的玻璃是今年初在拉斯维加斯消费电子产品展上面世的。

  11. Spectroscopy of supernova host galaxies from the SDSS-II SN survey with the SDSS and BOSS spectrographs

    Science.gov (United States)

    Olmstead, Matthew Dwaune

    Type Ia supernovae (SNeIa) have been used as standard candles to measure cosmological distances. The initial discovery of the accelerated expansion of the universe was performed using ~50 SNe Ia. Large SNe surveys have increased the number of spectroscopically-confirmed SNe Ia to over a thousand with redshift coverage beyond z = 1. We are now in the age of abundant photometry without the ability for full follow-up spectroscopy of all SN candidates. SN cosmology using these large samples will increasingly rely on robust photometric classification of SN candidates. Photometric classification will increase the sample by including faint SNe as these are preferentially not observed with follow-up spectroscopy. The primary concern with using photometrically classified SNe Ia in cosmology is when a core-collapse SNe is incorrectly classified as an SN Ia. This can be mitigated by obtaining the host galaxy redshift of each SN candidate and using this information as a prior in the photometric classification, removing one degree of freedom. To test the impact of redshift on photometric classification, I have performed an assessment on photometric classification of candidates from the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. I have tested the classification with and without redshift priors by looking at the change of photometric classification, the effect of data quality on photometric classification, and the effect of SN light curve properties on photometric classification. Following our suggested classification scheme, there are a total of 1038 photometrically classified SNe Ia when using a flat redshift prior and 1002 SNe~Ia with the spectroscopic redshift. For 912 (91.0%) candidates classified as likely SNe Ia without redshift information, the classification is unchanged when adding the host galaxy redshift. Finally, I investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. When using the SALT2

  12. A prospective, randomized, multisite clinical evaluation of a transparent absorbent acrylic dressing and a hydrocolloid dressing in the management of Stage II and shallow Stage III pressure ulcers.

    Science.gov (United States)

    Brown-Etris, Marie; Milne, Catherine; Orsted, Heather; Gates, Judy L; Netsch, Debra; Punchello, Marion; Couture, Nancy; Albert, Martine; Attrell, Edie; Freyberg, Julie

    2008-04-01

    To compare clinical performance of a transparent absorbent acrylic dressing (3M Tegaderm Absorbent Clear Acrylic Dressing ]TAAD[; 3M Company, St Paul, MN) and a hydrocolloid dressing (HD ]DuoDERM CGF, ConvaTec, ER Squibb & Sons, Princeton, NJ[) in the management of Stage II and shallow Stage III pressure ulcers. Prospective, open-label, randomized, comparative, multisite clinical evaluation. Patients were followed up for a maximum of 56 days or until their ulcer healed. At weekly intervals, investigators conducted wound assessments and dressing performance evaluations. Wound care clinics, home care, and long-term care. Thirty-five patients received the TAAD, and 37 received the HD. Dressing performance assessments, patient comfort, dressing wear time, and wound healing were measured. The majority of investigator assessments favored the TAAD. Considerations given included the ability to center dressings over the ulcer (P = .005), ability to assess the ulcer before (P < .001) and after (P < .001) absorption, barrier properties (P = .039), patient comfort during removal (P < .001), overall patient comfort (P = .048), conformability before (P = .026) and after (P = .001) absorption, ease of removal (P < .001), nonadherence to wound bed (P < .001), residue in the wound (P = .002), residue on periwound skin (P < .001), and odor after absorption (P = .016). Overall satisfaction favored the TAAD (P < .001), and a high value was placed on its transparent feature (P < .001). Mean (SD) wear time for the TAAD was 5.7 (2.55) days compared with 4.7 (2.29) days for the HD (P = .086). This 1-day difference in wear time was clinically noticeable by the investigators (P = .035). Wound closure for the 2 dressing groups was nearly identical (P = .9627). Performance results favored the TAAD over the HD as standard treatment for Stage II and shallow Stage III pressure ulcers.

  13. ISO spectroscopy of compact HII regions in the Galaxy - II. Ionization and elemental abundances

    NARCIS (Netherlands)

    Martin-Hernandez, NL; Peeters, E; Morisset, C; Tielens, AGGM; Cox, P; Roelfsema, PR; Baluteau, JP; Schaerer, D; Mathis, JS; Damour, F; Churchwell, E; Kessler, MF

    2002-01-01

    Based on the ISO spectral catalogue of compact H II regions by Peeters et al. (2002), we present a first analysis of the hydrogen recombination and atomic fine-structure lines originated in the ionized gas. The sample consists of 34 H II regions located at galactocentric distances between R-Gal = 0

  14. Measuring galaxy clustering and the evolution of [C II] mean intensity with far-IR line intensity mapping during 0.5 < z < 1.5

    Energy Technology Data Exchange (ETDEWEB)

    Uzgil, B. D.; Aguirre, J. E.; Lidz, A. [University of Pennsylvania, Philadelphia, PA 19104 (United States); Bradford, C. M., E-mail: badeu@sas.upenn.edu [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)

    2014-10-01

    Infrared fine-structure emission lines from trace metals are powerful diagnostics of the interstellar medium in galaxies. We explore the possibility of studying the redshifted far-IR fine-structure line emission using the three-dimensional (3D) power spectra obtained with an imaging spectrometer. The intensity mapping approach measures the spatio-spectral fluctuations due to line emission from all galaxies, including those below the individual detection threshold. The technique provides 3D measurements of galaxy clustering and moments of the galaxy luminosity function. Furthermore, the linear portion of the power spectrum can be used to measure the total line emission intensity including all sources through cosmic time with redshift information naturally encoded. Total line emission, when compared to the total star formation activity and/or other line intensities, reveals evolution of the interstellar conditions of galaxies in aggregate. As a case study, we consider measurement of [C II] autocorrelation in the 0.5 < z < 1.5 epoch, where interloper lines are minimized, using far-IR/submillimeter balloon-borne and future space-borne instruments with moderate and high sensitivity, respectively. In this context, we compare the intensity mapping approach to blind galaxy surveys based on individual detections. We find that intensity mapping is nearly always the best way to obtain the total line emission because blind, wide-field galaxy surveys lack sufficient depth and deep pencil beams do not observe enough galaxies in the requisite luminosity and redshift bins. Also, intensity mapping is often the most efficient way to measure the power spectrum shape, depending on the details of the luminosity function and the telescope aperture.

  15. Searching gravitational microlensing events in the galaxy spiral arms by EROS II; Recherche d'evenements de microlentille gravitationnelle dans les bras spiraux de la galaxie avec EROS II

    Energy Technology Data Exchange (ETDEWEB)

    Derue, Frederic [Paris-11 Univ., 91 Orsay (France)

    1999-04-15

    The EROS II experiment is searching for microlensing events due to compact massive objects passing through the line-of-sight of luminous stars. These objects are candidates to explain the baryonic component of Dark Matter in our Galaxy. EROS II was dedicated to different lines-of-sight: Small and Large Magellanic Clouds, Galactic Centre and 4 directions towards the Spiral Arms of the Galaxy. This thesis presents the first search for microlensing towards these last lines-of-sight (about 9 million stars). Simple criteria based on the search for significant fluctuations allowed one to discover a low noise sample of 7 candidates to the microlensing effect, with an average timescale of 50 days. A detailed analysis of the light curve of one candidate allows us to give a confidence interval on its mass 2.7 x 10{sup -3} < M/M{sub 0} < 0.84 at 95% CL. The amplification curve of another candidate shows a modulation which can be interpreted as a microlensing effect acting on a binary source, with an orbital period of P{sub 0} = 50 {+-} 3 days. To improve the knowledge of the distance of the target stars, we have combined observations of EROS II with bibliographic sources on associations of stars linked with the spiral arm features, and we have developed a program to find variable stars. Ten cepheids have thus been found. Distances obtained with different methods are in rough agreement with each other. The average optical depth measured towards the four directions is {tau}-bar = 0.45{sub 0.11}{sup +0.23} x 10{sup -6}. It is compatible with expectations from simple galactic models. The long duration of most events favours interpretation of lensing by objects belonging to the disk instead of the halo. It also seems that some events due to bulge lenses have influenced measurements towards the line-of-sight which is closest to the Galactic Centre. Observation continue towards spiral arms. More accurate measurements should be obtained with increase of statistics, allowing one to

  16. The Star Formation Histories of Local Group Dwarf Galaxies II. Searching For Signatures of Reionization

    CERN Document Server

    Weisz, Daniel R; Skillman, Evan D; Holtzman, Jon; Gilbert, Karoline M; Dalcanton, Julianne J; Williams, Benjamin F

    2014-01-01

    We search for signatures of reionization in the star formation histories (SFHs) of 38 Local Group dwarf galaxies (10$^4$ $<$ M$_{\\star}$ $<$ 10$^9$ M$_{\\odot}$). The SFHs are derived from color-magnitude diagrams using archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. Only five quenched galaxies (And V, And VI, And XIII, Leo IV, Hercules) are consistent with forming the bulk of their stars before reionization, when full uncertainties are considered. Observations of 13 of the predicted `true fossils' identified by Bovill & Ricotti show that only two (Hercules and Leo IV) indicate star formation quenched by reionization. However, both are within the virial radius of the Milky Way and evidence of tidal disturbance complicates this interpretation. We argue that the late-time gas capture scenario posited by Ricotti for the low mass, gas-rich, and star-forming fossil candidate Leo T is observationally indistinguishable from simple gas retention. Given the ambiguity between environment...

  17. HI Imaging Observations of Superthin Galaxies. II. IC2233 and the Blue Compact Dwarf NGC2537

    CERN Document Server

    Matthews, Lynn D

    2007-01-01

    We have used the VLA to image the HI 21-cm line emission in the edge-on Sd galaxy IC2233 and the blue compact dwarf NGC2537. We also present new optical B,R, and H alpha imaging of IC2233 obtained with the WIYN telescope. Despite evidence of localized massive star formation, IC2233 has a low surface brightness disk with a low global star formation rate (~0.05 M_sun/yr), and no significant 21-cm radio continuum emission. The HI and ionized gas disks of IC2233 are clumpy and vertically distended, with scale heights comparable to the young stars. Both the stellar and HI disks of IC2233 appear flared, and we also find a vertically extended, rotationally anomalous HI component extending to z~2.4 kpc. The HI disk exhibits a mild lopsidedness as well as a global corrugation pattern with a period of ~7 kpc and an amplitude of ~150 pc. To our knowledge, this is the first time corrugations of the gas disk have been reported in an external galaxy; these undulations may be linked to bending instabilities or to underlying...

  18. Structure in the 3D Galaxy Distribution. II. Voids and Watersheds of Local Maxima and Minima

    Science.gov (United States)

    Way, M. J.; Gazis, P. R.; Scargle, Jeffrey D.

    2015-01-01

    The major uncertainties in studies of the multi-scale structure of the universe arise not from observational errors but from the variety of legitimate definitions and detection methods for individual structures. To facilitate the study of these methodological dependencies, we have carried out 12 different analyses defining structures in various ways. This has been done in a purely geometrical way by utilizing the HOP algorithm as a unique parameter-free method of assigning groups of galaxies to local density maxima or minima. From three density estimation techniques (smoothing kernels, Bayesian blocks, and self-organizing maps) applied to three data sets (the Sloan Digital Sky Survey Data Release 7, the Millennium simulation, and randomly distributed points) we tabulate information that can be used to construct catalogs of structures connected to local density maxima and minima. We also introduce a void finder that utilizes a method to assemble Delaunay tetrahedra into connected structures and characterizes regions empty of galaxies in the source catalog.

  19. On the dynamical state of galaxy clusters: insights from cosmological simulations II.

    Science.gov (United States)

    Cui, Weiguang; Power, Chris; Borgani, Stefano; Knebe, Alexander; Lewis, Geraint F.; Murante, Giuseppe; Poole, Gregory B.

    2016-10-01

    Using a suite of cosmology simulations of a sample of >120 galaxy clusters with log (MDM, vir) ≤ 14.5. We compare clusters that form in purely dark matter run and their counterparts in hydro runs and investigate 4 independent parameters, that are normally used to classify dynamical state. We find that the virial ratio η in hydro-dynamical runs is ˜10 per cent lower than in the DM run, and there is no clear separation between the relaxed and unrelaxed clusters for any parameter. Further, using the velocity dispersion deviation parameter ζ, which is defined as the ratio between cluster velocity dispersion σ and the theoretical prediction σ _t = √{G M_{total}/R}, we find that there is a linear correlation between the virial ratio η and this ζ parameter. We propose to use this ζ parameter, which can be easily derived from observed galaxy clusters, as a substitute of the η parameter to quantify the cluster dynamical state.

  20. A Turbulent Origin for Flocculent Spiral Structure in Galaxies: II. Observations and Models of M33

    CERN Document Server

    Elmegreen, B G; Elmegreen, D M; Cuillandre, J C; Elmegreen, Bruce G.; Leitner, Samuel N.; Elmegreen, Debra Meloy; Cuillandre, Jean-Charles

    2003-01-01

    Fourier transform power spectra of azimuthal scans of the optical structure of M33 are evaluated for B, V, and R passbands and fit to fractal models of continuum emission with superposed star formation. Power spectra are also determined for Halpha. The best models have intrinsic power spectra with 1D slopes of around -0.7pm0.7, significantly shallower than the Kolmogorov spectrum (slope =-1.7) but steeper than pure noise (slope=0). A fit to the power spectrum of the flocculent galaxy NGC 5055 gives a steeper slope of around -1.5pm0.2, which could be from turbulence. Both cases model the optical light as a superposition of continuous and point-like stellar sources that follow an underlying fractal pattern. Foreground bright stars are clipped in the images, but they are so prominent in M33 that even their residual affects the power spectrum, making it shallower than what is intrinsic to the galaxy. A model consisting of random foreground stars added to the best model of NGC 5055 fits the observed power spectrum...

  1. The GALEX Arecibo SDSS Survey II: The Star Formation Efficiency of Massive Galaxies

    CERN Document Server

    Schiminovich, David; Kauffmann, Guinevere; Fabello, Silvia; Wang, Jing; Hummels, Cameron; Lemonias, Jenna; Moran, Sean M; Wu, Ronin; Giovanelli, Riccardo; Haynes, Martha P; Heckman, Timothy M; Basu-Zych, Antara R; Blanton, Michael R; Brinchmann, Jarle; Budavari, Tamas; Goncalves, Thiago; Johnson, Benjamin D; Kennicutt, Robert C; Madore, Barry F; Martin, Christopher D; Rich, Michael R; Tacconi, Linda J; Thilker, David A; Wild, Vivienne; Wyder, Ted K

    2010-01-01

    We use measurements of the HI content, stellar mass and star formation rates in ~190 massive galaxies with stellar masses greater than 10^10 Msun, obtained from the Galex Arecibo SDSS Survey (GASS) described in Paper I (Catinella et al. 2010) to explore the global scaling relations associated with the bin-averaged ratio of the star formation rate over the HI mass, which we call the HI-based star formation efficiency (SFE). Unlike the mean specific star formation rate, which decreases with stellar mass and stellar mass surface density, the star formation efficiency remains relatively constant across the sample with a value close to SFE = 10^-9.5 yr^-1 (or an equivalent gas consumption timescale of ~3 Gyr). Specifically, we find little variation in SFE with stellar mass, stellar mass surface density, NUV-r color and concentration. We interpret these results as an indication that external processes or feedback mechanisms that control the gas supply are important for regulating star formation in massive galaxies....

  2. Galaxy Interactions in Compact Groups II: abundance and kinematic anomalies in HCG 91c

    CERN Document Server

    Vogt, F P A; Borthakur, S; Verdes-Montenegro, L; Heckman, T M; Yun, M S; Chambers, K C

    2015-01-01

    Galaxies in Hickson Compact Group 91 (HCG 91) were observed with the WiFeS integral field spectrograph as part of our ongoing campaign targeting the ionized gas physics and kinematics inside star forming members of compact groups. Here, we report the discovery of HII regions with abundance and kinematic offsets in the otherwise unremarkable star forming spiral HCG 91c. The optical emission line analysis of this galaxy reveals that at least three HII regions harbor an oxygen abundance ~0.15 dex lower than expected from their immediate surroundings and from the abundance gradient present in the inner regions of HCG 91c. The same star forming regions are also associated with a small kinematic offset in the form of a lag of 5-10 km/s with respect to the local circular rotation of the gas. HI observations of HCG 91 from the Very Large Array and broadband optical images from Pan-STARRS suggest that HCG 91c is caught early in its interaction with the other members of HCG 91. We discuss different scenarios to explain...

  3. The EFIGI catalogue of 4458 nearby galaxies with morphology II. Statistical properties along the Hubble sequence

    CERN Document Server

    de Lapparent, Valérie; Bertin, Emmanuel

    2011-01-01

    The EFIGI catalogue of 4458 galaxies provides a reference database of the morphological properties of nearby galaxies, with 16 shape attributes describing their various dynamical components, their texture and environment, and with a dense sampling of all Hubble types. This catalogue allows us to derive a quantitative description of the Hubble Sequence in terms of the specific morphological features of the various types. The variations of the EFIGI morphological attributes with type confirm that the Hubble sequence is a decreasing sequence of bulge-to-total ratio and an increasing sequence of disk contribution to the total flux. There is nevertheless a large dispersion of approximately 5 types for a given bulge-to-total ratio, due to the fact that the Hubble sequence is primarily based on the strength and pitch angle of the spiral arms, independently from the bulge-to-total ratio. The grand spiral design is also related to a steep decrease in visible dust from types Sb to Sbc-Sc. In contrast, the scattered and...

  4. 2MTF II. New Parkes 21-cm observations of 303 southern galaxies

    CERN Document Server

    Hong, Tao; Masters, Karen L; Springob, Christopher M; Macri, Lucas M; Koribalski, Barbel S; Jones, D Heath; Jarrett, Tom H; Crook, Aidan C

    2013-01-01

    We present new 21-cm neutral hydrogen (HI) observations of spiral galaxies for the 2MASS Tully Fisher (2MTF) survey. Using the 64-m Parkes radio telescope multibeam system we obtain 152 high signal-to-noise HI spectra from which we extract 148 high-accuracy (< 5% error) velocity widths and derive reliable rotation velocities. The observed sample consists of 303 southern (\\delta < -40\\deg) galaxies selected from the MASS Redshift Survey (2MRS) with K_s <11.25 mag, cz < 10,000 km/s and axis ratio b/a < 0.5. The HI observations reported in this paper will be combined with new HI spectra from the Green Bank and Arecibo telescopes, together producing the most uniform Tully-Fisher survey ever constructed (in terms of sky coverage). In particular, due to its near infrared selection, 2MTF will be significantly more complete at low Galactic latitude (|b|<15\\deg) and will provide a more reliable map of peculiar velocities in the local universe.

  5. Intragroup diffuse light in compact groups of galaxies II. HCG 15, 35 and 51

    CERN Document Server

    Da Rocha, C; de Oliveira, C Mendes

    2008-01-01

    This continuing study of intragroup light in compact groups of galaxies aims to establish new constraints to models of formation and evolution of galaxy groups, specially of compact groups, which are a key part in the evolution of larger structures, such as clusters. In this paper we present three additional groups (HCG 15, 35 and 51) using deep wide field $B$ and $R$ band images observed with the LAICA camera at the 3.5m telescope at the Calar Alto observatory (CAHA). This instrument provides us with very stable flatfielding, a mandatory condition for reliably measuring intragroup diffuse light. The images were analyzed with the OV\\_WAV package, a wavelet technique that allows us to uncover the intragroup component in an unprecedented way. We have detected that 19, 15 and 26% of the total light of HCG 15, 35 and 51, respectively, is in the diffuse component, with colours that are compatible with old stellar populations and with mean surface brightness that can be as low as $28.4 {\\rm B mag arcsec^{-2}}$. Dyn...

  6. Properties of Bulgeless Disk Galaxies II. Star Formation as a Function of Circular Velocity

    CERN Document Server

    Watson, Linda C; Lisenfeld, Ute; Wong, Man-Hong; Boeker, Torsten; Schinnerer, Eva

    2012-01-01

    We study the relation between the surface density of gas and star formation rate in twenty moderately-inclined, bulgeless disk galaxies (Sd-Sdm Hubble types) using CO(1-0) data from the IRAM 30m telescope, HI emission line data from the VLA/EVLA, H-alpha data from the MDM Observatory, and PAH emission data derived from Spitzer IRAC observations. We specifically investigate the efficiency of star formation as a function of circular velocity (v_circ). Previous work found that the vertical dust structure and disk stability of edge-on, bulgeless disk galaxies transition from diffuse dust lanes with large scale heights and gravitationally-stable disks at v_circ 120 km/s. We find no transition in star formation efficiency (Sigma_SFR/Sigma_HI+H2) at v_circ = 120 km/s, or at any other circular velocity probed by our sample (v_circ = 46 - 190 km/s). Contrary to previous work, we find no transition in disk stability at any circular velocity in our sample. Assuming our sample has the same dust structure transition as t...

  7. STRUCTURE IN THE 3D GALAXY DISTRIBUTION. II. VOIDS AND WATERSHEDS OF LOCAL MAXIMA AND MINIMA

    Energy Technology Data Exchange (ETDEWEB)

    Way, M. J. [Also at NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA. (United States); Gazis, P. R.; Scargle, Jeffrey D., E-mail: Michael.J.Way@nasa.gov, E-mail: PGazis@sbcglobal.net, E-mail: Jeffrey.D.Scargle@nasa.gov [NASA Ames Research Center, Space Science Division, Moffett Field, CA 94035 (United States)

    2015-01-20

    The major uncertainties in studies of the multi-scale structure of the universe arise not from observational errors but from the variety of legitimate definitions and detection methods for individual structures. To facilitate the study of these methodological dependencies, we have carried out 12 different analyses defining structures in various ways. This has been done in a purely geometrical way by utilizing the HOP algorithm as a unique parameter-free method of assigning groups of galaxies to local density maxima or minima. From three density estimation techniques (smoothing kernels, Bayesian blocks, and self-organizing maps) applied to three data sets (the Sloan Digital Sky Survey Data Release 7, the Millennium simulation, and randomly distributed points) we tabulate information that can be used to construct catalogs of structures connected to local density maxima and minima. We also introduce a void finder that utilizes a method to assemble Delaunay tetrahedra into connected structures and characterizes regions empty of galaxies in the source catalog.

  8. Young Galaxy Candidates in the Hubble Frontier Fields. II. MACS,J0416-2403

    CERN Document Server

    Infante, Leopoldo; Laporte, Nicolas; Troncoso, Paulina; Molino, Alberto; Diego, Jose M; Bauer, Franz E; Zitrin, Adi; Moustakas, John; Huang, Xingxing; Shu, Xinwen; Bina, David; Brammer, Gabriel B; Broadhurst, Tom; Ford, Holland C; Garcia, Stefano; Kim, Sam

    2015-01-01

    We searched for z > 7 Lyman-break galaxies (LBGs) in the optical-to-mid-infrared Hubble Frontier Field and associated parallel field observations of the strong-lensing cluster MACS J0416-2403. We discovered 22 candidates, of which six lie at z > 9 and one lies at z > 10. Based on the Hubble and Spitzer photometry, all have secure photometric redshifts and a negligible probability of being at lower redshifts, according to their peak probability ratios, R. This substantial increase in the number of known high-redshift galaxies allows a solid determination of the luminosity function at z > 8. The number of high-z candidates in the parallel field is considerably higher than that in the Abell 2744 parallel field. Our candidates have median stellar masses of log(M_*) ~ 8.40^{+0.55}_{-0.31}~Msun, SFRs of ~ 1.6^{+0.5}_{-0.4} Msun yr^-1, and SFR-weighted ages of < 310^{+70}_{-140} Myr. Finally, we are able to put strong constraints on the z = 7,8,9 and 10 luminosity functions. One of the objects in the cluster fiel...

  9. Variable stars in the Fornax dSph Galaxy. II. Pulsating stars below the horizontal branch

    CERN Document Server

    Poretti, Ennio; Held, Enrico V; Greco, Claudia; Mateo, Mario; Dell'Arciprete, Luca; Rizzi, Luca; Gullieuszik, Marco; Maio, Marcella

    2008-01-01

    We have carried out an intensive survey of the northern region of the Fornax dwarf spheroidal galaxy with the aim of detecting the galaxy's short--period pulsating stars (P<0.25 days). Observations collected over three consecutive nights with the Wide Field Imager of the 2.2m MPI telescope at ESO allowed us to detect 85 high-amplitude (0.20-1.00 mag in B-light) variable stars with periods in the range from 0.046 to 0.126 days, similar to SX Phoenicis stars in Galactic metal-poor stellar populations. The plots of the observed periods vs. the B and V magnitudes show a dispersion largely exceeding the observational errors. To disentangle the matter, we separated the first-overtone from the fundamental-mode pulsators and tentatively identified a group of subluminous variables, about 0.35 mag fainter than the others. Their nature as either metal-poor intermediate-age stars or stars formed by the merging of close binary systems is discussed. The rich sample of the Fornax variables also led us to reconstruct the ...

  10. A Foreground Removal Strategy for future C[II] Intensity Mapping Experiments: Insights From Galaxies Selected by Stellar Mass and Redshift

    CERN Document Server

    Sun, Guochao; Viero, Marco P; Bock, Jamie; Bradford, C Matt; Chang, Tzu-Ching; Cheng, Yun-Ting; Cooray, Asantha; Crites, Abigail; Hailey-Dunsheath, Steve; Hunacek, Jonathon; Uzgil, Bade; Zemcov, Michael

    2016-01-01

    Intensity mapping provides a unique avenue to understand the epoch of reionization (EoR), which occurred approximately 500 million to 1 billion years after the Big Bang. The C[II] 158$\\mu$m fine-structure line is one of the brightest emission lines of typical star-forming galaxies and a promising tracer of the global star-formation activity during the epoch of reionization. However, C[II] intensity maps are contaminated by interloping CO rotational line emission ($3 \\leq J_{\\rm upp} \\leq 6$) from lower-redshift galaxies, whose total power is a function of the population's stochasticity. Here we present a model of CO contamination from foreground galaxies to guide the masking strategy of future C[II] intensity mapping experiments. The model is based on empirical measurements of the mean and scatter of the bolometric infrared luminosities, converted to CO line strengths, of galaxies at $z 8$. We find that the addition of scatter, parameterized by a log-normal distribution with $\\sigma = 0.33\\pm 0.04$\\,dex, to ...

  11. ALMA [C II] 158 μm Detection of a Redshift 7 Lensed Galaxy behind RXJ1347.1‑1145

    Science.gov (United States)

    Bradač, Maruša; Garcia-Appadoo, Diego; Huang, Kuang-Han; Vallini, Livia; Quinn Finney, Emily; Hoag, Austin; Lemaux, Brian C.; Borello Schmidt, Kasper; Treu, Tommaso; Carilli, Chris; Dijkstra, Mark; Ferrara, Andrea; Fontana, Adriano; Jones, Tucker; Ryan, Russell; Wagg, Jeff; Gonzalez, Anthony H.

    2017-02-01

    We present the results of ALMA spectroscopic follow-up of a z = 6.766 Lyα emitting galaxy behind the cluster RX J1347.1‑1145. We report the detection of [C ii] 158 μm line fully consistent with the Lyα redshift and with the peak of the optical emission. Given the magnification of μ = 5.0 ± 0.3, the intrinsic (corrected for lensing) luminosity of the [C ii] line is L [C ii] = {1.4}-0.3+0.2× {10}7 {L}ȯ , roughly ∼5 times fainter than other detections of z ∼ 7 galaxies. The result indicates that low L [C ii] in z ∼ 7 galaxies compared to the local counterparts might be caused by their low metallicities and/or feedback. The small velocity offset ({{Δ }}v={20}-40+140 {km} {{{s}}}-1) between the Lyα and [C ii] line is unusual, and may be indicative of ionizing photons escaping. These observations are based on the following ALMA data: ADS/JAO.ALMA#2015.1.00091.S. They are also associated with programs Spitzer #90009, 60034, 00083, 50610, 03550, 40593, and HST # GO10492, GO11591, GO12104, and GO13459. Furthermore based on multi-year KECK programs.

  12. Galaxies in the Early Universe

    DEFF Research Database (Denmark)

    Krogager, Jens-Kristian

    analyses are biased towards the brightest galaxies at all times (as these are easier to observe and identify). A complementary method relies on the absorption imprint from neutral gas in galaxies, the so-called damped Ly absorbers (DLAs) seen towards distant bright objects. This thesis seeks to understand...... how the absorption selected galaxies relate to the emission selected galaxies by identifying the faint glow from the absorbing galaxies at redshift z 2. In Chapters 2 and 3, the emission properties of DLAs are studied in detail using state-of-the-art instrumentation. The specific DLA studied......), there might exist a bias against dusty foreground absorbers due to the reddening causing the background quasars to appear star-like in their optical colours. In Chapters 4 and 5, these hypothesized dusty absorbers are sought for through a combination of optical and near-infrared colour criteria. While a large...

  13. Structure in the 3D Galaxy Distribution: II. Voids and Watersheds of Local Maxima and Minima

    CERN Document Server

    Way, M J; Scargle, Jeffrey D

    2014-01-01

    The major uncertainties in studies of the multi-scale structure of the Universe arise not from observational errors but from the variety of legitimate definitions and detection methods for individual structures. To facilitate the study of these methodological dependencies we have carried out 12 different analyses defining structures in various ways. This has been done in a purely geometrical way by utilizing the HOP algorithm as a unique parameter-free method of assigning groups of galaxies to local density maxima or minima. From three density estimation techniques (smoothing kernels, Bayesian Blocks and self organizing maps) applied to three data sets (the Sloan Digital Sky Survey Data Release 7, the Millennium Simulation and randomly distributed points) we tabulate information that can be used to construct catalogs of structures connected to local density maxima and minima. The resulting sizes follow continuous multi-scale distributions with no indication of the presence of a discrete hierarchy. We also int...

  14. How to bend galaxy disc profiles II: stars surfing the bar in anti-truncated discs

    CERN Document Server

    Herpich, Jakob; Rix, Hans-Walter; Martig, Marie; Dutton, Aaron A

    2015-01-01

    Simple numerical models can produce the observed radial breaks in the stellar surface density profile of late-type galaxies by varying only one parameter, the initial halo spin {\\lambda}. Here we analyse these simulations in more detail in an effort to identify the physical mechanism that leads to the formation of anti-truncations (Type-III profiles). We find that orbital resonances with a central bar drive stellar orbits from circular orbits with small semi-major axes to rather eccentric orbits with large semi-major axes. These orbits then form a disk-like configuration with high radial dispersion and rotation far below the circular velocity. This will manifest itself in photometry as an anti-truncated (Type-III) outer stellar disk. Whether such outer disks -- with qualitatively new dynamics -- exist in nature can be tested by future observations.

  15. The power spectrum and bispectrum of SDSS DR11 BOSS galaxies II: cosmological interpretation

    CERN Document Server

    Gil-Marín, Héctor; Noreña, Jorge; Cuesta, Antonio J; Samushia, Lado; Percival, Will J; Wagner, Christian; Manera, Marc; Schneider, Donald P

    2014-01-01

    We examine the cosmological implications of the measurements of the linear growth rate of cosmological structure obtained in a companion paper from the power spectrum and bispectrum monopoles of the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey Data, Release 11, CMASS galaxies. This measurement was of $f^{0.43}\\sigma_8$, where $\\sigma_8$ is the amplitude of dark matter density fluctuations, and $f$ is the linear growth rate, at the effective redshift of the survey, $z_{\\rm eff}=0.57$. In conjunction with Cosmic Microwave Background (CMB) data, interesting constraints can be placed on models with non-standard neutrino properties and models where gravity deviates from general relativity on cosmological scales. In particular, the sum of the masses of the three species of the neutrinos is constrained to $m_\

  16. Preparation and characterization of a novel nano-absorbent based on multi-cyanoguanidine modified magnetic chitosan and its highly effective recovery for Hg(II) in aqueous phase.

    Science.gov (United States)

    Wang, Yang; Qi, Yongxin; Li, Yanfeng; Wu, Jianjun; Ma, Xiaojie; Yu, Cui; Ji, Lei

    2013-09-15

    A new kind of nano-absorbent with the entirely novel structure, nano-absorbent of multi-cyanogunidine modified magnetic chitosan (CG-MCS nano-absorbent), has been firstly synthesized by using the functionalized chitosan and cross-linking agent with cyanoguanidine group simultaneously. The resulting nano-absorbent was characterized by means of the Fourier transform infrared spectra (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), elemental analysis and vibrating sample magnetometer (VSM). The resulting nano-absorbent basen on multi-cyanoguanidine modified magnetic chitosan has been demonstrated holding highly effective recovery for mercury ions, in other words, it showed both the extraordinary adsorption capacity for Hg(II) at high initial concentration and the strong removal ability for it at low concentration, the maximum adsorption capacity was up to 285 mg g(-1) and the removal percentage could reach 96% at low concentration. Meanwhile, the resulting CG-MCS nano-absorbent also showed a high selectivity adsorption for Hg(II) among coexisting heavy metals and the good regeneration performance.

  17. Narrow He II emission in star-forming galaxies at low metallicity. Stellar wind emission from a population of very massive stars

    Science.gov (United States)

    Gräfener, G.; Vink, J. S.

    2015-06-01

    Context. In a recent study, star-forming galaxies with He ii λ1640 emission at moderate redshifts between 2 and 4.6 have been found to occur in two modes that are distinguished by the width of their He ii emission lines. Broad He ii emission has been attributed to stellar emission from a population of evolved Wolf-Rayet (WR) stars. The origin of narrow He ii emission is less clear but has been attributed to nebular emission excited by a population of very hot Pop III stars formed in pockets of pristine gas at moderate redshifts. Aims: We propose an alternative scenario for the origin of the narrow He ii emission, namely very massive stars (VMS) at low metallicity (Z), which form strong but slow WR-type stellar winds due to their proximity to the Eddington limit. Methods: We estimated the expected He ii line fluxes and equivalent widths based on wind models for VMS and Starburst99 population synthesis models and compared the results with recent observations of star-forming galaxies at moderate redshifts. Results: The observed He ii line strengths and equivalent widths are in line with what is expected for a population of VMS in one or more young super-clusters located within these galaxies. Conclusions: In our scenario the two observed modes of He ii emission originate from massive stellar populations in distinct evolutionary stages at low Z (~0.01 Z⊙). If this interpretation is correct, there is no need to postulate the existence of Pop III stars at moderate redshifts to explain the observed narrow He ii emission. An interesting possibility is the existence of self-enriched VMS with similar WR-type spectra at extremely low Z. Stellar He ii emission from such very early generations of VMS may be detectable in future studies of star-forming galaxies at high redshifts with the James Webb Space Telescope (JWST). The fact that the He ii emission of VMS is largely neglected in current population synthesis models will generally affect the interpretation of the

  18. Narrow He II emission in star-forming galaxies at low metallicity. Stellar wind emission from a population of Very Massive Stars

    CERN Document Server

    Gräfener, G

    2015-01-01

    In a recent study star-forming galaxies with HeII emission at moderate redshifts have been found to occur in two modes, distinguished by the width of their HeII emission lines. Broad HeII emission has been attributed to stellar emission from a population of evolved Wolf-Rayet (WR) stars while narrow HeII emission has been attributed to nebular emission excited by a population of very hot PopIII stars formed in pockets of pristine gas at moderate redshifts. In this work we propose an alternative scenario for the origin of the narrow HeII emission, namely very massive stars (VMS) at low metallicity (Z) which form strong but slow WR-type stellar winds due to their proximity to the Eddington limit. We estimate the expected HeII line fluxes and equivalent widths based on wind models for VMS and population synthesis models, and compare the results with recent observations of star-forming galaxies at moderate redshifts. The observed HeII line strengths and equivalent widths are in line with what is expected for a po...

  19. Sound Absorbers

    Science.gov (United States)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  20. STELLAR POPULATIONS AND STRUCTURAL PROPERTIES OF ULTRA FAINT DWARF GALAXIES, CANES VENATICI I, BOOeTES I, CANES VENATICI II, AND LEO IV

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Sakurako [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Arimoto, Nobuo; Yamada, Yoshihiko [National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan); Onodera, Masato, E-mail: okamoto@pku.edu.cn [Institute for Astronomy, ETH Zuerich, Wolfgang-Pauli-Strasse 27, 8093 Zuerich (Switzerland)

    2012-01-10

    We take deep images of four ultra faint dwarf (UFD) galaxies, Canes Venatici I (CVn I), Booetes I (Booe I), Canes Venatici II (CVn II), and Leo IV, using the Suprime-Cam on the Subaru Telescope. Color-magnitude diagrams (CMDs) extend below main-sequence turnoffs (MSTOs) and yield measurements of the ages of stellar populations. The stellar populations of three faint galaxies, the Booe I, CVn II, and Leo IV dwarf spheroidal galaxies (dSphs), are estimated to be as old as the Galactic globular cluster M92. We confirm that Booe I dSph has no intrinsic color spread in the MSTO and no spatial difference in the CMD morphology, which indicates that Booe I dSph is composed of an old single stellar population. One of the brightest UFDs, CVn I dSph, shows a relatively younger age ({approx}12.6 Gyr) with respect to Booe I, CVn II, and Leo IV dSphs, and the distribution of red horizontal branch (HB) stars is more concentrated toward the center than that of blue HB stars, suggesting that the galaxy contains complex stellar populations. Booe I and CVn I dSphs show the elongated and distorted shapes. CVn II dSph has the smallest tidal radius of a Milky Way satellite and has a distorted shape, while Leo IV dSph shows a less concentrated spherical shape. The simple stellar population of faint UFDs indicates that the gases in their progenitors were removed more effectively than those of brighter dSphs at the occurrence of their initial star formation. This is reasonable if the progenitors of UFDs belong to less massive halos than those of brighter dSphs.

  1. The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II) V. Exploring a local underdensity in the Southern Sky

    CERN Document Server

    Boehringer, Hans; Bristow, Martyn; Collins, Chris A

    2014-01-01

    Several claims have been made that we are located in a locally underdense region of the Universe based on observations of supernovae and galaxy density distributions. Two recent studies of K-band galaxy surveys have provided new support for a local underdensity in the galaxy distribution out to distances of 200 - 300 Mpc. If confirmed, such large local underdensities would have important implications on the interpretation of local measurements of cosmological parameters. Galaxy clusters have been shown to be ideal probes to trace the large-scale structure of the Universe. In this paper we study the local density distribution in the southern sky with the X-ray detected galaxy clusters from the REFLEX II cluster survey. From the normalized comoving number density of clusters we find an average underdensity of ~30 - 40% in the redshift range out to z ~0.04 (~170 Mpc) in the southern extragalactic sky with a significance larger than 3.4sigma. On larger scales from 300 Mpc to over 1 Gpc the density distribution ap...

  2. Dust Properties of C ii Detected z ˜ 5.5 Galaxies: New HST/WFC3 Near-IR Observations

    Science.gov (United States)

    Barisic, I.; Faisst, A. L.; Capak, P. L.; Pavesi, R.; Riechers, D. A.; Scoville, N. Z.; Cooke, K.; Kartaltepe, J. S.; Casey, C. M.; Smolcic, V.

    2017-08-01

    We examine the rest-frame ultraviolet (UV) properties of 10 [C ii]λ158 μm-detected galaxies at z ˜ 5.5 in COSMOS using new Hubble Space Telescope/Wide Field Camera 3 near-infrared imaging. Together with pre-existing 158 μm continuum and [C ii] line measurements by the Atacama Large Millimeter/submillimeter Array, we study their dust attenuation properties on the IRX-β diagram, which connects the total dust emission (\\propto {IRX}={log}({L}{FIR}/{L}1600)) to the line-of-sight dust column (∝ β). We find systematically bluer UV continuum spectral slopes (β) compared to previous low-resolution ground-based measurements, which relieves some of the tension between models of dust attenuation and observations at high redshifts. While most of the galaxies are consistent with local starburst or Small Magellanic Cloud-like dust properties, we find galaxies with low IRX values and a large range in β that cannot be explained by models of a uniform dust distribution well mixed with stars. A stacking analysis of Keck/DEIMOS optical spectra indicates that these galaxies are metal-poor with young stellar populations that could significantly alter their spatial dust distribution.

  3. Study of the Sextans dwarf spheroidal galaxy from the DART Ca II triplet survey

    NARCIS (Netherlands)

    Battaglia, G.; Tolstoy, E.; Helmi, A.; Irwin, M.; Parisi, P.; Hill, V.; Jablonka, P.

    2011-01-01

    We use Very Large Telescope (VLT)/Fibre Large Array Multi Element Spectrograph (FLAMES) intermediate-resolution (R˜ 6500) spectra of individual red giant branch stars in the near-infrared Ca II triplet (CaT) region to investigate the wide-area metallicity properties and internal kinematics of the Se

  4. Is Draco II one of the faintest dwarf galaxies? First evidence from Keck/DEIMOS spectroscopy

    CERN Document Server

    Martin, Nicolas F; Ibata, Rodrigo A; Collins, Michelle L M; Laevens, Benjamin P M; Bell, Eric F; Rix, Hans-Walter; Ferguson, Annette M N; Chambers, Kenneth C; Wainscoat, Richard J; Waters, Christopher

    2015-01-01

    We present the first spectroscopic analysis of the faint and compact stellar system Draco II (Dra II, M_V=-2.9 +/- 0.8, r_h=19^{+8}_{-6} pc), recently discovered in the Pan-STARRS1 3\\pi survey. The observations, conducted with DEIMOS on the Keck II telescope, reveal a cold velocity peak with 9 member stars at a systemic heliocentric velocity =-347.6^{+1.7}_{-1.8} km/s, thereby confirming Dra II is a satellite of the Milky Way. We infer a marginally resolved velocity dispersion with \\sigma_{vr}=2.9 +/- 2.1 km/s, which hints that this system is kinematically hotter than implied from its baryonic mass alone and potentially dark-matter-dominated (\\log_{10}(M_{1/2})=5.5^{+0.4}_{-0.6} and log_{10}((M/L)_{1/2})=2.7^{+0.5}_{-0.8}, in Solar units). Furthermore, very weak Calcium triplet lines in the spectra of the high signal-to-noise member stars indicate that its metallicity is likely lower than that of the globular cluster NGC 2419 ([Fe/H]<-2.1). Finally, variations in the line strengths of two stars with simila...

  5. Study of the Sextans dwarf spheroidal galaxy from the DART CaII triplet survey

    NARCIS (Netherlands)

    Battaglia, G.; Tolstoy, E.; Helmi, A.; Irwin, M.; Parisi, P.; Hill, V.; Jablonka, P.

    2011-01-01

    We use Very Large Telescope (VLT)/Fibre Large Array Multi Element Spectrograph (FLAMES) intermediate-resolution (R similar to 6500) spectra of individual red giant branch stars in the near-infrared Ca ii triplet (CaT) region to investigate the wide-area metallicity properties and internal kinematics

  6. A cold metal poor cloud traced by a weak MgII absorption at z~0.45. First detection of SiI, CaI and FeI in a QSO absorber

    CERN Document Server

    D'Odorico, Valentina

    2007-01-01

    We present the observations of a weak MgII absorption system detected at z~0.452 in the UVES high resolution spectrum of the QSO HE0001-2340. The weakest of the two MgII components forming the system shows associated absorptions due to SiI, CaI and FeI observed for the first time in a QSO spectrum. We investigate the nature of this absorber by comparing its properties with those of different classes of absorbers (weak MgII, Damped Ly-alpha systems and local interstellar clouds) and reproducing its ionization conditions with photoionization models. The observed absorber belongs to the class of weak MgII systems on the basis of its equivalent width, however the relative strength of commonly observed transitions deviates significantly from those of the above mentioned absorbers. A rough estimate of the probability to cross such a system with a QSO line of sight is P~0.03. The presence of rare neutral transitions suggests that the cloud is shielded by a large amount of neutral Hydrogen. A detailed comparison of t...

  7. Comparative assessment of “plaque/media” change on three modalities of IVUS immediately after implantation of either everolimus-eluting bioresorbable vascular scaffold or everolimus-eluting metallic stent in Absorb II study

    NARCIS (Netherlands)

    Y. Zeng (Yaping); R. Cavalcante (Rafael); E. Tenekecioglu (Erhan); P. Suwannasom (Pannipa); Y. Sotomi (Yohei); C. Collet (Carlos); M. Abdelghani (Mohammad); H. Jonker (Hans); Digne, F. (Franck); Horstkotte, D. (Dieter); Zehender, M. (Manfred); Indolfi, C. (Ciro); F. Saia (Francesco); Fiorilli, R. (Rosario); B. Chevalier (Bernard); L. Bolognese (Leonardo); Goicolea, J. (Javier); Nie, S. (Shaoping); Y. Onuma (Yoshinobu); P.W.J.C. Serruys (Patrick); On Behalf Of The Investigators Of Absorb Ii Study,

    2017-01-01

    textabstractThe purpose of the study to assess the comparability of immediate changes in plaque/media volume (PV) on three modalities of intravascular ultrasound (IVUS) after implantation of either bioresorbable vascular scaffold (BVS) or everolimus-eluting metallic stent (EES) in Absorb II Study. T

  8. Variable stars in Local Group Galaxies - II. Sculptor dSph

    Science.gov (United States)

    Martínez-Vázquez, C. E.; Stetson, P. B.; Monelli, M.; Bernard, E. J.; Fiorentino, G.; Gallart, C.; Bono, G.; Cassisi, S.; Dall'Ora, M.; Ferraro, I.; Iannicola, G.; Walker, A. R.

    2016-11-01

    We present the identification of 634 variable stars in the Milky Way dwarf spheroidal (dSph) satellite Sculptor based on archival ground-based optical observations spanning ˜24 yr and covering ˜2.5 deg2. We employed the same methodologies as the `Homogeneous Photometry' series published by Stetson. In particular, we have identified and characterized one of the largest (536) RR Lyrae samples so far in a Milky Way dSph satellite. We have also detected four Anomalous Cepheids, 23 SX Phoenicis stars, five eclipsing binaries, three field variable stars, three peculiar variable stars located above the horizontal branch - near to the locus of BL Herculis - that we are unable to classify properly. Additionally, we identify 37 long period variables plus 23 probable variable stars, for which the current data do not allow us to determine the period. We report positions and finding charts for all the variable stars, and basic properties (period, amplitude, mean magnitude) and light curves for 574 of them. We discuss the properties of the RR Lyrae stars in the Bailey diagram, which supports the coexistence of subpopulations with different chemical compositions. We estimate the mean mass of Anomalous Cepheids (˜1.5 M⊙) and SX Phoenicis stars (˜1 M⊙). We discuss in detail the nature of the former. The connections between the properties of the different families of variable stars are discussed in the context of the star formation history of the Sculptor dSph galaxy.

  9. Water Masers in the Andromeda Galaxy: II. Where Do Masers Arise?

    CERN Document Server

    Amiri, Nikta

    2016-01-01

    We present a comparative multi-wavelength analysis of water maser-emitting regions and non-maser-emitting luminous 24 micron star-forming regions in the Andromeda Galaxy (M31) to identify the sites most likely to produce luminous water masers useful for astrometry and proper motion studies. Included in the analysis are Spitzer 24 micron photometry, Herschel 70 and 160 micron photometry, H$\\alpha$ emission, dust temperature, and star formation rate. We find significant differences between the maser-emitting and non-maser-emitting regions: water maser-emitting regions tend to be more IR-luminous and show higher star formation rates. The five water masers in M31 are consistent with being analogs of water masers in Galactic star-forming regions and represent the high-luminosity tail of a larger (and as yet undetected) population. Most regions likely to produce water masers bright enough for proper motion measurements using current facilities have already been surveyed, but we suggest three ways to detect addition...

  10. Dynamical Models of Elliptical Galaxies -- II. M87 and its Globular Clusters

    CERN Document Server

    Agnello, A; Romanowsky, A J; Brodie, J P

    2014-01-01

    We study the Globular Cluster (GC) system of the nearby elliptical galaxy M87 using the newly available dataset with accurate kinematics (Strader et al.2011). We find evidence for three distinct sub-populations of GCs in terms of colours, kinematics and radial profiles. We show that a decomposition into three populations (blue, intermediate and red GCs) is statistically preferred to one with two or four populations, and relate them to the stellar profile. We exploit the sub-populations to derive dynamical constraints on the mass and Dark Matter (DM) content of M87 out to $\\sim100$ kpc. We use a class of global mass-estimators (from Paper I), obtaining mass measurements at different locations. M87's DM fraction changes from $\\approx$0.2 at the starlight's effective radius (6 kpc) to $\\approx$0.95 at the distance probed by the most extended, blue GCs (135 kpc). We supplement this with \\textit{virial decompositions}, exploiting the dynamical model to produce a separation into multiple components. These yield the...

  11. Broad-band properties of the CfA Seyfert Galaxies. II - Infrared to millimeter properties

    Science.gov (United States)

    Edelson, R. A.; Malkan, M. A.; Rieke, G. H.

    1987-01-01

    IR and mm observations of the 48 Seyfert 1 and 2 galaxies (SG1s and SG2s) of the CfA sample (Huchra and Berg, 1987) are reported. Data obtained (1) in the NIR using the 1.55-m reflector at Stewart Observatory and the 3-m IRTF during 1984-1986, (2) in the FIR with IRAS, and (3) at 1.3 mm using the 12-m NRAO telescope at KPNO in June 1984 are presented in extensive tables and graphs and characterized in detail. None of the objects was detected at 1.3 mm, and the IR spectra of the SG2s are found to be significantly steeper (indicating thermal emission) than those of SG1s and QSOs (nonthermal emission). Turnover in the IR emission below 100 microns (in half of the objects detected at three or more IRAS wavelengths) is shown to be consistent with an accretion disk in dust-free SG1s and with unusually warm (35-65 K) dust in SG2s. It is inferred that a 60-100-micron cool excess is masking turnover in the other SGs, so that a general association of SG nuclei with strong star formation can be confirmed.

  12. The MUSIC of Galaxy Clusters II: X-ray global properties and scaling relations

    CERN Document Server

    Biffi, Veronica; De Petris, Marco; Valdarnini, Riccardo; Yepes, Gustavo; Gottlöber, Stefan

    2014-01-01

    We present the X-ray properties and scaling relations of a large sample of clusters extracted from the Marenostrum MUltidark SImulations of galaxy Clusters (MUSIC) dataset. We focus on a sub-sample of 179 clusters at redshift z~0.11, with 3.2e14M_sun/h

  13. Emission Line Galaxies in the STIS Parallel Survey II: Star Formation Density

    Science.gov (United States)

    Teplitz, Harry I.; Collins, Nicholas R.; Gardner, Jonathan P.; Hill, Robert S.; Rhodes, Jason

    2002-01-01

    We present the luminosity function of [OII]-emitting galaxies at a median redshift of z = 0.9, as measured in the deep spectroscopic data in the STIS Parallel Survey (SPS). The luminosity function shows strong evolution from the local value, as expected. By using random lines of sight, the SPS measurement complements previous deep single field studies. We calculate the density of inferred star formation at this redshift by converting from [OII] to H(alpha) line flux as a function of absolute magnitude and find rho = 0.052 +/- 0.017 Solar mass/yr Mpc(sup -3) at a median redshift z approx. 0.9 within the range 0.46 less than z less than 1.415 (H(sub 0) = 50 km/s Mpc(sup -l), Omega(sub M) = 1.0, Omega(sub lambda) = 0.0). This density is consistent with a (1 + z)(sup )4 evolution in global star formation since z approx. 1. To reconcile the density with similar measurements made by surveys targeting H(alpha) may require substantial extinction correction.

  14. SPECTROSCOPY OF LUMINOUS COMPACT BLUE GALAXIES IN DISTANT CLUSTERS. II. PHYSICAL PROPERTIES OF dE PROGENITOR CANDIDATES

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, S. M. [South African Astronomical Observatory, Observatory, 7935 Cape Town (South Africa); Wirth, Gregory D. [W. M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela HI 96743 (United States); Bershady, M. A. [Washburn Observatories, U. Wisconsin—Madison, 475 N. Charter St., Madison, WI 53706 (United States); Randriamampandry, S. M., E-mail: crawford@saao.ac.za, E-mail: gregory.wirth@gmail.com, E-mail: mab@astro.wisc.edu [Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Durban 4041 (South Africa)

    2016-02-01

    Luminous Compact Blue Galaxies (LCBGs) are an extreme star-bursting population of galaxies that were far more common at earlier epochs than today. Based on spectroscopic and photometric measurements of LCBGs in massive (M > 10{sup 15} M{sub ⊙}), intermediate redshift (0.5 < z < 0.9) galaxy clusters, we present their rest-frame properties including star formation rate, dynamical mass, size, luminosity, and metallicity. The appearance of these small, compact galaxies in clusters at intermediate redshift helps explain the observed redshift evolution in the size–luminosity relationship among cluster galaxies. In addition, we find the rest-frame properties of LCBGs appearing in galaxy clusters are indistinguishable from field LCBGs at the same redshift. Up to 35% of the LCBGs show significant discrepancies between optical and infrared indicators of star formation, suggesting that star formation occurs in obscured regions. Nonetheless, the star formation for LCBGs shows a decrease toward the center of the galaxy clusters. Based on their position and velocity, we estimate that up to 10% of cluster LCBGs are likely to merge with another cluster galaxy. Finally, the observed properties and distributions of the LCBGs in these clusters lead us to conclude that we are witnessing the quenching of the progenitors of dwarf elliptical galaxies that dominate the number density of present-epoch galaxy clusters.

  15. A GMOS-N IFU study of the central H ii region in the blue compact dwarf galaxy NGC 4449: kinematics, nebular metallicity and star formation

    Science.gov (United States)

    Kumari, Nimisha; James, Bethan L.; Irwin, Mike J.

    2017-10-01

    We use integral field spectroscopic (IFS) observations from the Gemini Multi-Object Spectrograph North (GMOS-N) to study the central H ii region in a nearby blue compact dwarf (BCD) galaxy NGC 4449. The IFS data enable us to explore the variation of physical and chemical conditions of the star-forming region and the surrounding gas on spatial scales as small as 5.5 pc. Our kinematical analysis shows possible signatures of shock ionization and shell structures in the surroundings of the star-forming region. The metallicity maps of the region, created using direct Te and indirect strong line methods (R23, O3N2 and N2), do not show any chemical variation. From the integrated spectrum of the central H ii region, we find a metallicity of 12 + log(O/H) = 7.88 ± 0.14 ({˜ }0.15^{+0.06}_{-0.04} Z⊙) using the direct method. Comparing the central H ii region metallicity derived here with those of H ii regions throughout this galaxy from previous studies, we find evidence of increasing metallicity with distance from the central nucleus. Such chemical inhomogeneities can be due to several mechanisms, including gas loss via supernova blowout, galactic winds or metal-poor gas accretion. However, we find that the localized area of decreased metallicity aligns spatially with the peak of star-forming activity in the galaxy, suggesting that gas accretion may be at play here. Spatially resolved IFS data for the entire galaxy are required to confirm the metallicity inhomogeneity found in this study and determine its possible cause.

  16. Outliers from the Mass--Metallicity Relation II: A Sample of Massive Metal-Poor Galaxies from SDSS

    CERN Document Server

    Peeples, Molly S; Stanek, K Z

    2008-01-01

    We present a sample of 42 high-mass low-metallicity outliers from the mass--metallicity relation of star-forming galaxies. These galaxies have stellar masses that span log(M_*/M_sun) ~9.4 to 11.1 and are offset from the mass--metallicity relation by -0.3 to -0.85 dex in 12+log(O/H). In general, they are extremely blue, have high star formation rates for their masses, and are morphologically disturbed. Tidal interactions are expected to induce large-scale gas inflow to the galaxies' central regions, and we find that these galaxies' gas-phase oxygen abundances are consistent with large quantities of low-metallicity gas from large galactocentric radii diluting the central metal-rich gas. We conclude with implications for deducing gas-phase metallicities of individual galaxies based solely on their luminosities, specifically in the case of long gamma-ray burst host galaxies.

  17. 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, ...

  18. Mapping Large-Scale Gaseous Outflows in Ultraluminous Infrared Galaxies with Keck II ESI Spectra: Spatial Extent of the Outflow

    CERN Document Server

    Martin, C L

    2006-01-01

    The kinematics of neutral gas and warm ionized gas have been mapped in one-dimension across ultraluminous starburst galaxies using interstellar absorption and emission lines, in Keck II ESI spectra. Blue-shifted absorption is found along more of the slit than anticipated, exceeding scales of 15 kpc across several systems. The large velocity gradient measured across some of these outflows is inconsistent with a flow diverging from the central starburst -- angular momentum conservation reduces the rotational velocity of an outflow as it expands. More widespread star formation, likely triggered by the merger, probably drives these outflows, although some models suggest the collision itself could generate a wind by shock heating interstellar gas throughout the disk. Young mergers with separated nuclei present the highest outflow masses, due mainly to the larger area over which the cool gas can be detected. In a typical ULIG, the mass carried by the cool phase of the outflow is around 10^8Msun, or a few percent of...

  19. A Study of the Type II-Plateau Supernova 1999gi, and the Distance to its Host Galaxy, NGC 3184

    CERN Document Server

    Leonard, D C; Li, W; Matheson, T; Kirshner, R P; Chornock, R; Van Dyk, S D; Berlind, P; Calkins, M L; Challis, P M; Garnavich, P M; Jha, S; Mahdavi, A M; Leonard, Douglas C.; Filippenko, Alexei V.; Li, Weidong; Matheson, Thomas; Kirshner, Robert P.; Chornock, Ryan; Dyk, Schuyler D. Van; Berlind, Perry; Calkins, Michael L.; Challis, Peter M.; Garnavich, Peter M.; Jha, Saurabh; Mahdavi, Andisheh

    2002-01-01

    We present optical spectra and photometry sampling the first six months after discovery of supernova (SN) 1999gi in NGC 3184. SN 1999gi is shown to be a Type II-plateau event with a photometric plateau lasting until about 100 days after discovery. The reddening values resulting from five independent techniques are all consistent with an upper bound of E(B-V) < 0.45 mag established by comparing the early-time color of SN 1999gi with that of an infinitely hot blackbody, and yield a probable reddening of E(B-V) = 0.21 +/- 0.09 mag. Using the expanding photosphere method (EPM), we derive a distance to SN 1999gi of 11.1^{+2.0}_{-1.8} Mpc and an explosion date of 1999 December 5.8^{+3.0}_{-3.1}, or 4.1^{+3.0}_{-3.1} days prior to discovery. This distance is consistent with a recent Tully-Fisher distance derived to NGC 3184 (D ~ 11.59 Mpc), but is somewhat closer than the Cepheid distances derived to two galaxies that have generally been assumed to be members of a small group containing NGC 3184 (NGC 3319, D = 13...

  20. An optical/NIR survey of globular clusters in early-type galaxies II. Ages of GC systems and the relation to galaxy morphology

    CERN Document Server

    Chies-Santos, A L; Kuntschner, H; Anders, P; Wehner, E M; Strader, J; Brodie, J P; Santos, J F C

    2010-01-01

    Context: Some photometric studies of extragalactic globular cluster (GC) systems using the optical and near-infrared colour combination have suggested the presence of a large fraction of intermediate-age (2-8 Gyrs) GCs. Aims: We investigate the age distributions of GC systems in 14 E/S0 galaxies. Methods: We carry out a differential comparison of the (g-z) vs. (g-K) two-colour diagrams for GC systems in the different galaxies in order to see whether there are indications of age differences. We also compare the different GC systems with a few simple stellar population models. Results: No significant difference is detected in the mean ages of GCs among elliptical galaxies. S0 galaxies on the other hand, show evidence for younger GCs. Surprisingly, this appears to be driven by the more metal-poor clusters. The age distribution of GCs in NGC4365 seems to be similar to that of other large ellipticals (e.g. NGC4486, NGC4649). Padova SSPs with recently released isochrones for old ages (14 Gyrs) show less of an offse...

  1. Type Ia Supernova Properties as a Function of the Distance to the Host Galaxy in the SDSS-II SN Survey

    Energy Technology Data Exchange (ETDEWEB)

    Galbany, Lluis [Institut de Fisica d' Altes Energies (IFAE), Barcelona (Spain); et al.

    2012-08-20

    We use type-Ia supernovae (SNe Ia) discovered by the SDSS-II SN Survey to search for dependencies between SN Ia properties and the projected distance to the host galaxy center, using the distance as a proxy for local galaxy properties (local star-formation rate, local metallicity, etc.). The sample consists of almost 200 spectroscopically or photometrically confirmed SNe Ia at redshifts below 0.25. The sample is split into two groups depending on the morphology of the host galaxy. We fit light-curves using both MLCS2k2 and SALT2, and determine color (AV, c) and light-curve shape (delta, x1) parameters for each SN Ia, as well as its residual in the Hubble diagram. We then correlate these parameters with both the physical and the normalized distances to the center of the host galaxy and look for trends in the mean values and scatters of these parameters with increasing distance. The most significant (at the 4-sigma level) finding is that the average fitted AV from MLCS2k2 and c from SALT2 decrease with the projected distance for SNe Ia in spiral galaxies. We also find indications that SNe in elliptical galaxies tend to have narrower light-curves if they explode at larger distances, although this may be due to selection effects in our sample. We do not find strong correlations between the residuals of the distance moduli with respect to the Hubble flow and the galactocentric distances, which indicates a limited correlation between SN magnitudes after standardization and local host metallicity.

  2. Dynamical models of elliptical galaxies - II. M87 and its globular clusters

    Science.gov (United States)

    Agnello, A.; Evans, N. W.; Romanowsky, A. J.; Brodie, J. P.

    2014-08-01

    We study the globular cluster (GC) system of the nearby elliptical galaxy M87 using the newly available data set with accurate kinematics provided by Strader et al. We find evidence for three distinct subpopulations of GCs in terms of colours, kinematics and radial profiles. A decomposition into three populations - blue, intermediate and red GCs - is statistically preferred to one with two or four populations. The existence of three components has been suggested before, but here we are able to identify them robustly and relate them to the stellar profile. We exploit the subpopulations to derive dynamical constraints on the mass and dark matter (DM) content of M87 out to ˜100 kpc. We deploy a class of global mass estimators, developed in Paper I, obtaining mass measurements at different locations. The DM fraction in M87 changes from ≈0.2 at the effective radius of the stellar light (0.02° or 6 kpc) to ≈0.95 at the distance probed by the most extended, blue GCs (0.47° or 135 kpc). We complete this analysis with virial decompositions, in which the dynamical model is used to produce velocity dispersions, which in turn are used to separate the GC populations. This ensures that the three subpopulations are simultaneously consistent with the same underlying mass profile. These yield the luminous mass as 5.5^{+1.5}_{-2.0} × 10^{11} M_{⊙} and the DM within 135 kpc as 8.0^{+1.0}_{-4.0} × 10^{12} M_{⊙}. The inner DM density behaves as ρ ˜ r-γ with γ ≈ 1.6. This is steeper than the cosmologically preferred cusp of ρ ˜ r-1 and may provide evidence of DM contraction. Finally, we combine the GC separation into three subpopulations with the Jeans equations, obtaining information on the orbital structure of the GC system. The centrally concentrated red GCs exhibit tangential anisotropy, consistent with the depletion of radial orbits by tidal shredding. The most extended blue GCs have an isotropic velocity-dispersion tensor in the central parts, which becomes

  3. Preparing for JWST Observations. Insights from First Light and Assembly of Galaxies GTO Programs II: Studying galaxy properties with MIRI Spectroscopy

    Science.gov (United States)

    Garcia Marin, Macarena; Wright, Gillian; Rieke, George; MIRI GTO Team

    2017-06-01

    The MIRI instrument, a result of the collaborative work of a consortium of European and US institutes, is the only Mid-IR science instrument on board of the James Webb Space Telescope. It will achieve unprecedented sensitivity and spatial resolution in the 5-28 microns wavelength range. A significant part of the MIRI GTO time will be dedicated to extragalactic observations, with the aim of covering a broad range of redshifts and giving new insights to galaxy history through time. While some of the programme will use deep MIRI images complemented with NIR observations, in this talk I will focus on the spectroscopic studies of galaxies planned by the MIRI team. At redshifts of about 7-8 we will study the reionization epoch, by observing spectroscopically confirmed targets. The strong emission lines predicted for these galaxies will be measured with the MIRI MRS (an integral field spectrometer).Moving closer in redshift, MIRI will be able to provide spatially resolved spectroscopy of massive dusty star forming galaxies at redshifts of about 3 or higher. This will give us the opportunity to study obscured AGNs, internal extinction and star formation activity, and gas-kpc scales kinematics. Finally, in the local Universe, we will observe the nuclei of well-known nearby galaxies with the MIRI MRS and the NIRSpec IFU. The spectra will yield new insights into the distribution, physical conditions, and kinematics of the various gas components (ionized, atomic, or molecular) in the immediate vicinity of the nucleus.In this contribution I will present this overall spectroscopic GTO program, giving insight into the observing strategies we plan to use for optimally implementing our observations.

  4. Fueling the central engine of radio galaxies. II. The footprints of AGN feedback on the ISM of 3C 236

    NARCIS (Netherlands)

    Labiano, A.; Garcia-Burillo, S.; Combes, F.; Usero, A.; Soria-Ruiz, R.; Tremblay, G.; Neri, R.; Fuente, A.; Morganti, R.; Oosterloo, T.

    2013-01-01

    Context. There is growing observational evidence of active galactic nuclei (AGN) feedback on the interstellar medium (ISM) of radio-quiet and radio-loud galaxies. While AGN feedback is expected to be more common at high-redshift objects, studying local universe galaxies helps to better characterize

  5. Mapping stellar content to dark matter halos. II. Halo mass is the main driver of galaxy quenching

    CERN Document Server

    Zu, Ying

    2015-01-01

    We develop a simple yet comprehensive method to distinguish the underlying drivers of galaxy quenching, using the clustering and galaxy-galaxy lensing of red and blue galaxies in SDSS. Building on the iHOD framework developed by Zu & Mandelbaum (2015a), we consider two quenching scenarios: 1) a "halo" quenching model in which halo mass is the sole driver for turning off star formation in both centrals and satellites; and 2) a "hybrid" quenching model in which the quenched fraction of galaxies depends on their stellar mass while the satellite quenching has an extra dependence on halo mass. The two best-fit models describe the red galaxy clustering and lensing equally well, but halo quenching provides significantly better fits to the blue galaxies above $10^{11} M_\\odot/h^2$. The halo quenching model also correctly predicts the average halo mass of the red and blue centrals, showing excellent agreement with the direct weak lensing measurements of locally brightest galaxies. Models in which quenching is not ...

  6. Mean Hα+[N ii]+[S ii] EW inferred for star-forming galaxies atz ˜ 5.1-5.4 using high-qualitySpitzer/IRAC photometry

    Science.gov (United States)

    Rasappu, N.; Smit, R.; Labbé, I.; Bouwens, R. J.; Stark, D. P.; Ellis, R. S.; Oesch, P. A.

    2016-10-01

    Recent Spitzer/InfraRed Array Camera (IRAC) photometric observations have revealed that rest-frame optical emission lines contribute significantly to the broad-band fluxes of high-redshift galaxies. Specifically, in the narrow redshift range z ˜ 5.1-5.4 the [3.6]-[4.5] colour is expected to be very red, due to contamination of the 4.5 μm band by the dominant Hα line, while the 3.6 μm filter is free of nebular emission lines. We take advantage of new reductions of deep Spitzer/IRAC imaging over the Great Observatories Origins Deep Survey-North+South fields (Labbé et al. 2015) to obtain a clean measurement of the mean Hα equivalent width (EW) from the [3.6]-[4.5] colour in the redshift range z = 5.1-5.4. The selected sources either have measured spectroscopic redshifts (13 sources) or lie very confidently in the redshift range z = 5.1-5.4 based on the photometric redshift likelihood intervals (11 sources). Our zphot = 5.1-5.4 sample and zspec = 5.10-5.40 spectroscopic sample have a mean [3.6]-[4.5] colour of 0.31 ± 0.05 and 0.35 ± 0.07 mag, implying a rest-frame EW (Hα+[N II]+[S II]) of 665 ± 53 and 707 ± 74 Å, respectively, for sources in these samples. These values are consistent albeit slightly higher than derived by Stark et al. at z ˜ 4, suggesting an evolution to higher values of the Hα+[N II]+[S II] EW at z > 2. Using the 3.6 μm band, which is free of emission line contamination, we perform robust spectral energy distribution fitting and find a median specific star formation rate of sSFR = 17_{-5}^{+2} Gyr-1, 7_{-2}^{+1}× higher than at z ˜ 2. We find no strong correlation (<2σ) between the Hα+[N II]+[S II] EW and the stellar mass of sources. Before the advent of JWST, improvements in these results will come through an expansion of current spectroscopic samples and deeper Spitzer/IRAC measurements.

  7. Physical properties of simulated galaxy populations at z=2 -- II. Effects of physics ingredients other than cooling and outflows

    CERN Document Server

    Haas, Marcel R; Booth, C M; Vecchia, Claudio Dalla; Springel, Volker; Theuns, Tom; Wiersma, Robert P C

    2012-01-01

    We use hydrodynamical simulations from the OWLS project to investigate the dependence of the physical properties of galaxy populations at redshift 2 on the assumed star formation law, the equation of state imposed on the unresolved interstellar medium, the stellar initial mass function, the reionization history, and the assumed cosmology. This work complements that of Paper I, where we studied the effects of varying models for galactic winds driven by star formation and AGN. The normalisation of the matter power spectrum strongly affects the galaxy mass function, but has a relatively small effect on the physical properties of galaxies residing in haloes of a fixed mass. Reionization suppresses the stellar masses and gas fractions of low-mass galaxies, but by z = 2 the results are insensitive to the timing of reionization. The stellar initial mass function mainly determines the physical properties of galaxies through its effect on the efficiency of the feedback, while changes in the recycled mass and metal fra...

  8. Mapping stellar content to dark matter haloes - II. Halo mass is the main driver of galaxy quenching

    Science.gov (United States)

    Zu, Ying; Mandelbaum, Rachel

    2016-04-01

    We develop a simple yet comprehensive method to distinguish the underlying drivers of galaxy quenching, using the clustering and galaxy-galaxy lensing of red and blue galaxies in Sloan Digital Sky Survey. Building on the iHOD framework developed by Zu & Mandelbaum, we consider two quenching scenarios: (1) a `halo' quenching model in which halo mass is the sole driver for turning off star formation in both centrals and satellites; and (2) a `hybrid' quenching model in which the quenched fraction of galaxies depends on their stellar mass, while the satellite quenching has an extra dependence on halo mass. The two best-fitting models describe the red galaxy clustering and lensing equally well, but halo quenching provides significantly better fits to the blue galaxies above 1011 h-2 M⊙. The halo quenching model also correctly predicts the average halo mass of the red and blue centrals, showing excellent agreement with the direct weak lensing measurements of locally brightest galaxies. Models in which quenching is not tied to halo mass, including an age-matching model in which galaxy colour depends on halo age at fixed M*, fail to reproduce the observed halo mass for massive blue centrals. We find similar critical halo masses responsible for the quenching of centrals and satellites (˜1.5 × 1012 h-1 M⊙), hinting at a uniform quenching mechanism for both, e.g. the virial shock heating of infalling gas. The success of the iHOD halo quenching model provides strong evidence that the physical mechanism that quenches star formation in galaxies is tied principally to the masses of their dark matter haloes rather than the properties of their stellar components.

  9. A Multiwavelength Study of a Sample of 70 μm Selected Galaxies in the COSMOS Field : II. The Role of Mergers in Galaxy Evolution

    NARCIS (Netherlands)

    Kartaltepe, Jeyhan S.; Sanders, D. B.; Le Floc'h, E.; Frayer, D. T.; Aussel, H.; Arnouts, S.; Ilbert, O.; Salvato, M.; Scoville, N. Z.; Surace, J.; Yan, L.; Capak, P.; Caputi, K.; Carollo, C. M.; Cassata, P.; Civano, F.; Hasinger, G.; Koekemoer, A. M.; Le Fèvre, O.; Lilly, S.; Liu, C. T.; McCracken, H. J.; Schinnerer, E.; Smolčić, V.; Taniguchi, Y.; Thompson, D. J.; Trump, J.; Baldassare, V. F.; Fiorenza, S. L.

    2010-01-01

    We analyze the morphological properties of a large sample of 1503 70 μm selected galaxies in the COSMOS field spanning the redshift range 0.01

  10. PROBING THE PHYSICS OF NARROW LINE REGIONS IN ACTIVE GALAXIES. II. THE SIDING SPRING SOUTHERN SEYFERT SPECTROSCOPIC SNAPSHOT SURVEY (S7)

    Energy Technology Data Exchange (ETDEWEB)

    Dopita, Michael A.; Davies, Rebecca; Kewley, Lisa; Hampton, Elise; Sutherland, Ralph [RSAA, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Shastri, Prajval; Kharb, Preeti; Jose, Jessy; Bhatt, Harish; Ramya, S. [Indian Institute of Astrophysics, Koramangala 2 B Block, Bangalore 560034 (India); Scharwächter, Julia [LERMA, Observatoire de Paris, CNRS, UMR 8112, 61 Avenue de l’Observatoire, F-75014 Paris (France); Jin, Chichuan [Qian Xuesen Laboratory for Space Technology, Beijing (China); Banfield, Julie [CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW, 1710 Australia (Australia); Zaw, Ingyin [New York University (Abu Dhabi), 70 Washington Square South, New York, NY 10012 (United States); Juneau, Stéphanie [CEA-Saclay, DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); James, Bethan [Institute of Astronomy, Cambridge University, Madingley Road, Cambridge CB3 0HA (United Kingdom); Srivastava, Shweta, E-mail: Michael.Dopita@anu.edu.au [Astronomy and Astrophysics Division, Physical Research Laboratory, Ahmedabad 380009 (India)

    2015-03-15

    Here we describe the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) and present results on 64 galaxies drawn from the first data release. The S7 uses the Wide Field Spectrograph mounted on the ANU 2.3 m telescope located at the Siding Spring Observatory to deliver an integral field of 38 × 25 arcsec at a spectral resolution of R = 7000 in the red (530–710 nm), and R = 3000 in the blue (340–560 nm). From these data cubes we have extracted the narrow-line region spectra from a 4 arcsec aperture centered on the nucleus. We also determine the Hβ and [O iii] λ5007 fluxes in the narrow lines, the nuclear reddening, the reddening-corrected relative intensities of the observed emission lines, and the Hβ and [O iii] λ5007 luminosities determined from spectra for which the stellar continuum has been removed. We present a set of images of the galaxies in [O iii] λ5007, [N ii] λ6584, and Hα, which serve to delineate the spatial extent of the extended narrow-line region and also to reveal the structure and morphology of the surrounding H ii regions. Finally, we provide a preliminary discussion of those Seyfert 1 and Seyfert 2 galaxies that display coronal emission lines in order to explore the origin of these lines.

  11. INTERPRETING THE GLOBAL 21-cm SIGNAL FROM HIGH REDSHIFTS. II. PARAMETER ESTIMATION FOR MODELS OF GALAXY FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Mirocha, Jordan; Burns, Jack O. [Center for Astrophysics and Space Astronomy and Department of Astrophysical and Planetary Science, University of Colorado, Campus Box 389, Boulder, CO 80309 (United States); Harker, Geraint J. A., E-mail: mirocha@astro.ucla.edu [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

    2015-11-01

    Following our previous work, which related generic features in the sky-averaged (global) 21-cm signal to properties of the intergalactic medium, we now investigate the prospects for constraining a simple galaxy formation model with current and near-future experiments. Markov-Chain Monte Carlo fits to our synthetic data set, which includes a realistic galactic foreground, a plausible model for the signal, and noise consistent with 100 hr of integration by an ideal instrument, suggest that a simple four-parameter model that links the production rate of Lyα, Lyman-continuum, and X-ray photons to the growth rate of dark matter halos can be well-constrained (to ∼0.1 dex in each dimension) so long as all three spectral features expected to occur between 40 ≲ ν/MHz ≲ 120 are detected. Several important conclusions follow naturally from this basic numerical result, namely that measurements of the global 21-cm signal can in principle (i) identify the characteristic halo mass threshold for star formation at all redshifts z ≳ 15, (ii) extend z ≲ 4 upper limits on the normalization of the X-ray luminosity star formation rate (L{sub X}–SFR) relation out to z ∼ 20, and (iii) provide joint constraints on stellar spectra and the escape fraction of ionizing radiation at z ∼ 12. Though our approach is general, the importance of a broadband measurement renders our findings most relevant to the proposed Dark Ages Radio Explorer, which will have a clean view of the global 21-cm signal from ∼40 to 120 MHz from its vantage point above the radio-quiet, ionosphere-free lunar far-side.

  12. Large-scale HI in nearby radio galaxies (II): the nature of classical low-power radio sources

    CERN Document Server

    Emonts, B H C; Struve, C; Oosterloo, T A; van Moorsel, G; Tadhunter, C N; van der Hulst, J M; Brogt, E; Holt, J; Mirabal, N

    2010-01-01

    An important aspect of solving the long-standing question as to what triggers various types of Active Galactic Nuclei involves a thorough understanding of the overall properties and formation history of their host galaxies. This is the second in a series of papers that systematically study the large-scale properties of cold neutral hydrogen (HI) gas in nearby radio galaxies. The main goal is to investigate the importance of gas-rich galaxy mergers and interactions among radio-loud AGN. In this paper we present results of a complete sample of classical low-power radio galaxies. We find that extended Fanaroff & Riley type-I radio sources are generally not associated with gas-rich galaxy mergers or ongoing violent interactions, but occur in early-type galaxies without large (> 10^8 M_sun) amounts of extended neutral hydrogen gas. In contrast, enormous discs/rings of HI gas (with sizes up to 190 kpc and masses up to 2 x 10^10 M_sun) are detected around the host galaxies of a significant fraction of the compac...

  13. The growth of disks and bulges during hierarchical galaxy formation. II: metallicity, stellar populations and dynamical evolution

    CERN Document Server

    Tonini, Chiara; Wyithe, J Stuart B; Croton, Darren J

    2016-01-01

    We investigate the properties of the stellar populations of model galaxies, using the new semi-analytic model presented in Tonini et al. (2016a). This new model follows the angular momentum evolution of gas and stars, providing the base for a new star formation recipe, and treatment of the effects of mergers that depends on the central galaxy dynamical structure. We find that the new recipes have the effect of boosting the efficiency of the baryonic cycle in producing and recycling metals, as well as preventing minor mergers from diluting the metallicity of bulges and ellipticals. The model reproduces the stellar mass - stellar metallicity relation for galaxies above 1e10 solar masses, including Brightest Cluster Galaxies. Model disks, galaxies dominated by instability-driven components, and merger-driven objects each stem from different evolutionary channels. These model galaxies therefore occupy different loci in the galaxy mass - size relation, which we find to be in accord with the Atlas 3D classification...

  14. Chandra Reveals Twin X-ray Jets in the Powerful FR-II Radio Galaxy 3C353

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, J.; Stawarz, L.; Harris, D.E.; Siemiginowska, A.; Ostrowski, M.; Swain, M.R.; Hardcastle, M.J.; Goodger, J.L.; Iwasawa, K.; Edwards, P.G.

    2008-06-13

    We report X-ray imaging of the powerful FR II radio galaxy 3C 353 using the Chandra X-ray Observatory. 3C 353's two 4-inch wide and 2-feet long jets allow us to study in detail the internal structure of the large-scale relativistic outflows at both radio and X-ray photon energies with the sub-arcsecond spatial resolution provided by the VLA and Chandra instruments. In a 90 ks Chandra observation, we have detected X-ray emission from most radio structures in 3C 353, including the nucleus, the jet and the counterjet, the terminal jet regions (hotspots), and one radio lobe. We show that the detection of the X-ray emission associated with the radio knots and counterknots, which is most likely non-thermal in origin, puts several crucial constraints on the X-ray emission mechanisms in powerful large-scale jets of quasars and FR II sources. In particular, we show that this detection is inconsistent with the inverse-Compton model proposed in the literature, and instead implies a synchrotron origin of the X-ray jet photons. We also find that the width of the X-ray counterjet is possibly narrower than that measured in radio bands, that the radio-to-X-ray flux ratio decreases systematically downstream along the jets, and that there are substantial (kpc-scale) offsets between the positions of the X-ray and radio intensity maxima within each knot, whose magnitudes increase away from the nucleus. We discuss all these findings in the wider context of the physics of extragalactic jets, proposing some particular though not definitive solutions or interpretations for each problem. In general, we find that the synchrotron X-ray emission of extragalactic large-scale jets is not only shaped by the global hydrodynamical configuration of the outflows, but is also likely to be very sensitive to the microscopic parameters of the jet plasma. A complete, self-consistent model for the X-ray emission of extragalactic jets still remains elusive.

  15. 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.

  16. Radial metallicity gradients in spiral galaxies from H II regions and planetary nebulae: probing galactic chemical evolution

    Science.gov (United States)

    Stanghellini, Letizia

    2015-08-01

    Radial metallicity gradients, typically observed in spiral galaxies, are excellent constraints for chemical evolution models. The contemporary studies of the two stellar populations, whose progenitors have formed at different times, yield to the chemical and time constraining of the models. In this context, planetary nebula and HII region analysis proved to be ideal two-epochs test populations. We present an assortment of galaxies whose oxygen abundances have been determined both with weak- and strong-line methods, and whose radial metallicity gradients and their evolution in time have disclosed very interesting correlations with the galaxy characteristics. New results from our Gemini/GMOS observations, and a review of the best literature data, set the stage for a better understanding of spiral galaxy evolution.

  17. First Detections of the [N II] 122 micron Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe

    Science.gov (United States)

    Ferkinhoff, Carl; Brisbin, Drew; Nikola, Thomas; Parshley, Stephen C.; Stacey, Gordon J.; Phillips, Thomas G.; Falgarone, Edith; Benford, Dominic J.; Staguhn, Johannes G.; Tucker, Carol E.

    2011-01-01

    We report the first detections of the [N II] 122 micron line from a high-redshift galaxy. The line was strongly (>6(sigma)) detected from SMMJ02399-0136, and H1413 + 117 (the Cloverleaf QSO) using the Redshift (zeta) and Early Universe Spectrometer on the Caltech Submillimeter Observatory. The lines from both sources are quite bright with line to far-infrared (FIR) continuum luminosity ratios that are approx.7.0 x 10(exp -4) (Cloverleaf) and 2.1 x 10(exo -3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line to continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, approx.8%-17% of the molecUlar gas mass. The [O III]/[N II] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an active galactic nucleus (AGN). Using Our previous detection of the [O III] 88 micron line, the [O III]/[N II]line ratio for SMMJ02399-0136 indicates that the dominant source of the line emission is either stellar H II regions ionized by O9.5 stars, or the NLR of the AGN with ionization parameter log(U) = -3.3 to -4.0. A composite system, where 30%-50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of approx.200 M82-like starbursts accounting for all of the FIR emission and 43% of the [N II]line. The remainder may come from the NLR. This war!< demonstrates the utility of the [N II] and [O III] lines in constraining properties of the ionized medium.

  18. First Detections of the [N II] 122 micron Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe

    Science.gov (United States)

    Ferkinhoff, Carl; Brisbin, Drew; Nikola, Thomas; Parshley, Stephen C.; Stacey, Gordon J.; Phillips, Thomas G.; Falgarone, Edith; Benford, Dominic J.; Staguhn, Johannes G.; Tucker, Carol E.

    2011-01-01

    We report the first detections of the [N II] 122 micron line from a high-redshift galaxy. The line was strongly (>6(sigma)) detected from SMMJ02399-0136, and H1413 + 117 (the Cloverleaf QSO) using the Redshift (zeta) and Early Universe Spectrometer on the Caltech Submillimeter Observatory. The lines from both sources are quite bright with line to far-infrared (FIR) continuum luminosity ratios that are approx.7.0 x 10(exp -4) (Cloverleaf) and 2.1 x 10(exo -3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line to continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, approx.8%-17% of the molecUlar gas mass. The [O III]/[N II] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an active galactic nucleus (AGN). Using Our previous detection of the [O III] 88 micron line, the [O III]/[N II]line ratio for SMMJ02399-0136 indicates that the dominant source of the line emission is either stellar H II regions ionized by O9.5 stars, or the NLR of the AGN with ionization parameter log(U) = -3.3 to -4.0. A composite system, where 30%-50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of approx.200 M82-like starbursts accounting for all of the FIR emission and 43% of the [N II]line. The remainder may come from the NLR. This war!< demonstrates the utility of the [N II] and [O III] lines in constraining properties of the ionized medium.

  19. The VIPERS Multi-Lambda Survey. II. Diving with massive galaxies in 22 square degrees since z = 1.5

    Science.gov (United States)

    Moutard, T.; Arnouts, S.; Ilbert, O.; Coupon, J.; Davidzon, I.; Guzzo, L.; Hudelot, P.; McCracken, H. J.; Van Werbaeke, L.; Morrison, G. E.; Le Fèvre, O.; Comte, V.; Bolzonella, M.; Fritz, A.; Garilli, B.; Scodeggio, M.

    2016-05-01

    We investigate the evolution of the galaxy stellar mass function and stellar mass density from redshift z = 0.2 to z = 1.5 of a Ks 22.5) samples, respectively. The galaxy stellar mass function is measured with ~760 000 galaxies down to Ks ~ 22 and over an effective area of ~22.4 deg2, the latter of which drastically reduces the statistical uncertainties (i.e. Poissonian error and cosmic variance). We point out the importance of carefully controlling the photometric calibration, whose effect becomes quickly dominant when statistical uncertainties are reduced, which will be a major issue for future cosmological surveys with EUCLID or LSST, for instance. By exploring the rest-frame (NUV-r) vs. (r-Ks) colour-colour diagram with which we separated star-forming and quiescent galaxies, (1) we find that the density of very massive log (M∗/M⊙) > 11.5 galaxies is largely dominated by quiescent galaxies and increases by a factor 2 from z ~ 1 to z ~ 0.2, which allows for additional mass assembly through dry mergers. (2) We also confirm the scenario in which star formation activity is impeded above a stellar mass log(ℳ*SF/M⊙) = 10.64±0.01. This value is found to be very stable at 0.2 galaxies, and we finally (4) characterise another quenching mechanism that is required to explain the clear excess of low-mass quiescent galaxies that is observed at low redshift.

  20. The formation and evolution of high-redshift dusty galaxies

    Science.gov (United States)

    Ma, Jingzhe; Gonzalez, Anthony H.; Ge, Jian; Vieira, Joaquin D.; Prochaska, Jason X.; Spilker, Justin; Strandet, Maria; Ashby, Matthew; Noterdaeme, Pasquier; Lundgren, Britt; Zhao, Yinan; Ji, Tuo; Zhang, Shaohua; Caucal, Paul; SPT SMG Collaboration

    2017-01-01

    Star formation and chemical evolution are among the biggest questions in galaxy formation and evolution. High-redshift dusty galaxies are the best sites to investigate mass assembly and growth, star formation rates, star formation history, chemical enrichment, and physical conditions. My thesis is based on two populations of high-redshift dusty galaxies, submillimeter galaxies (SMGs) and quasar 2175 Å dust absorbers, which are selected by dust emission and dust absorption, respectively.For the SMG sample, I have worked on the gravitationally lensed dusty, star-forming galaxies (DSFGs) at 2.8 thesis is focused on the stellar masses and star formation rates of these objects by means of multi-wavelength spectral energy distribution (SED) modelling. The data include HST/WFC3, Spitzer/IRAC, Herschel/PACS, Herschel/SPIRE, APEX/Laboca and SPT. Compared to the star-forming main sequence (MS), these DSFGs have specific SFRs that lie above the MS, suggesting that we are witnessing ongoing strong starburst events that may be driven by major mergers. SPT0346-52 at z = 5.7, the most extraordinary source in the SPT survey for which we obtained Chandra X-ray and ATCA radio data, was confirmed to have the highest star formation surface density of any known galaxy at high-z.The other half of my thesis is focused on a new population of quasar absorption line systems, 2175 Å dust absorbers, which are excellent probes of gas and dust properties, chemical evolution and physical conditions in the absorbing galaxies. This sample was selected from the SDSS and BOSS surveys and followed up with the Echelle Spectrographs and Imager on the Keck-II telescope, the Red & Blue Channel Spectrograph on the Multiple Mirror Telescope, and the Ultraviolet and Visible Echelle Spectrograph onboard the Very Large Telescope. We found a correlation between the presence of the 2175 Å bump and other ingredients including high metallicity, high depletion level, overall low ionization state of gas, neutral

  1. BUDHIES II: A phase-space view of HI gas stripping and star-formation quenching in cluster galaxies

    CERN Document Server

    Jaffe, Yara L; Candlish, Graeme N; Poggianti, Bianca M; Sheen, Yun-Kyeong; Verheijen, Marc A W

    2015-01-01

    We investigate the effect of ram-pressure from the intracluster medium on the stripping of HI gas in galaxies in a massive, relaxed, X-ray bright, galaxy cluster at z=0.2 from the Blind Ultra Deep HI Environmental Survey (BUDHIES). We use cosmological simulations, and velocity vs. position phase-space diagrams to infer the orbital histories of the cluster galaxies. In particular, we embed a simple analytical description of ram-pressure stripping in the simulations to identify the regions in phase-space where galaxies are more likely to have been sufficiently stripped of their HI gas to fall below the detection limit of our survey. We find a striking agreement between the model predictions and the observed location of HI-detected and non-detected blue (late-type) galaxies in phase-space, strongly implying that ram-pressure plays a key role in the gas removal from galaxies, and that this can happen during their first infall into the cluster. However, we also find a significant number of gas-poor, red (early-typ...

  2. Recovering galaxy stellar population properties from broad-band spectral energy distribution fitting II. The case with unknown redshift

    CERN Document Server

    Pforr, Janine; Tonini, Chiara

    2013-01-01

    (Abridged) In a recent work we explored the dependence of galaxy stellar population properties derived from broad-band spectral energy distribution fitting on the fitting parameters, e.g. SFHs, age grid, metallicity, IMF, dust reddening, reddening law, filter setup and wavelength coverage. In this paper we consider also redshift as a free parameter in the fit and study whether one can obtain reasonable estimates of photometric redshifts and stellar population properties at once. We use mock star-forming as well as passive galaxies placed at various redshifts (0.5 to 3) as test particles. Mock star-forming galaxies are extracted from a semi-analytical galaxy formation model. We show that for high-z star-forming galaxies photometric redshifts, stellar masses and reddening can be determined simultaneously when using a broad wavelength coverage and a wide template setup in the fit. Masses are similarly well recovered (median ~ 0.2 dex) as at fixed redshift. For old galaxies with little recent star formation masse...

  3. Gas surface density, star formation rate surface density, and the maximum mass of young star clusters in a disk galaxy. II. The grand-design galaxy M51

    CERN Document Server

    Gonzalez-Lopezlira, Rosa A; Kroupa, Pavel

    2013-01-01

    We analyze the relationship between maximum cluster mass, and surface densities of total gas (Sigma_gas), molecular gas (Sigma_H_2), neutral gas (Sigma_HI) and star formation rate (Sigma_SFR) in the grand design galaxy M51, using published gas data and a catalog of masses, ages, and reddenings of more than 1800 star clusters in its disk, of which 223 are above the cluster mass distribution function completeness limit. We find for clusters older than 25 Myr that M_3rd, the median of the 5 most massive clusters, is proportional to Sigma_HI^0.4. There is no correlation with Sigma_gas, Sigma_H2, or Sigma_SFR. For clusters younger than 10 Myr, M_3rd is proportional to Sigma_HI^0.6, M_3rd is proportional to Sigma_gas^0.5; there is no correlation with either Sigma_H_2 or Sigma_SFR. The results could hardly be more different than those found for clusters younger than 25 Myr in M33. For the flocculent galaxy M33, there is no correlation between maximum cluster mass and neutral gas, but M_3rd is proportional to Sigma_g...

  4. ALMA unveils a triple merger and gas exchange in a hyper-luminous radio galaxy at z=2: the Dragonfly Galaxy (II)

    CERN Document Server

    Emonts, B H C; Lehnert, M D; Vernet, J; Gullberg, B; Villar-Martín, M; Nesvadba, N; Drouart, G; Ivison, R; Seymour, N; Wylezalek, D; Barthel, P

    2015-01-01

    The Dragonfly Galaxy (MRC0152-209), at redshift z~2, is one of the most vigorously star-forming radio galaxies in the Universe. What triggered its activity? We present ALMA Cycle 2 observations of cold molecular CO(6-5) gas and dust, which reveal that this is likely a gas-rich triple merger. It consists of a close double nucleus (separation ~4 kpc) and a weak CO-emitter at ~10 kpc distance, all of which have counterparts in HST/NICMOS imagery. The hyper-luminous starburst and powerful radio-AGN were triggered at this precoalescent stage of the merger. The CO(6-5) traces dense molecular gas in the central region, and complements existing CO(1-0) data, which revealed more widespread tidal debris of cold gas. We also find ~10$^{10}$ M(sun) of molecular gas with enhanced excitation at the highest velocities. At least 20-50% of this high-excitation, high-velocity gas shows kinematics that suggests it is being displaced and redistributed within the merger, although with line-of-sight velocities of |v| < 500 km/s...

  5. Galaxy Group at z=0.3 Associated with the Damped Lyman Alpha System Towards Quasar Q1127-145

    CERN Document Server

    Kacprzak, G G; Churchill, C W

    2010-01-01

    We performed a spectroscopic galaxy survey, complete to $m_{F814W}\\leq20.3$ ($L_B>0.15L_B^{\\star}$ at z=0.3), within 100x100'' of the quasar Q1127-145 ($z_{em}=1.18$). The VLT/UVES quasar spectrum contains three $z_{abs}<0.33$ MgII absorption systems. We obtained eight new galaxy redshifts, adding to the four previously known, and galaxy star formation rates (SFRs) and metallicities were computed where possible. A strong MgII system [$W_r(2796)=1.8$A], which is a known damped Ly$\\alpha$ absorber (DLA), had three previously identified galaxies; we found two additional galaxies associated with this system. These five galaxies form a group with diverse properties, such as a luminosity range of $0.04\\leq L_B\\leq0.63 L_B^{\\star}$, an impact parameter range of $17\\leq D \\leq 241$ kpc and velocity dispersion of $\\sigma$=115 km/s. The DLA group galaxy redshifts span beyond the 350 km/s velocity spread of the metallic absorption lines of the DLA itself. The two brightest group galaxies have SFRs of $\\sim$few $M_{\\o...

  6. G359.87+0.18: An FR II Radio Galaxy 15 Arcminutes from Sgr A*. Implications for the Scattering Region in the Galactic Center

    OpenAIRE

    Lazio, T. Joseph W.; Anantharamaiah, K. R.; W. M. Goss; Kassim, Namir E.; Cordes, James M.

    1998-01-01

    G359.87+0.18 is an enigmatic object located 15' from Sgr A*. It has been variously classified as an extragalactic source, Galactic jet source, and young supernova remnant. We present new observations of G359.87+0.18 between 0.33 and 15 GHz and use these to argue that this source is an Faranoff-Riley II radio galaxy. We are able to place a crude limit on its redshift of z > 0.1. The source has a spectral index \\alpha ...

  7. Being WISE II: Reducing the Influence of Star formation History on the Mass-to-Light Ratio of Quiescent Galaxies

    Science.gov (United States)

    Norris, Mark A.; Van de Ven, Glenn; Schinnerer, Eva; Crain, Robert A.; Meidt, Sharon; Groves, Brent; Bower, Richard G.; Furlong, Michelle; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-12-01

    Stellar population synthesis models can now reproduce the photometry of old stellar systems (age \\gt 2 Gyr) in the near-infrared (NIR) bands at 3.4 and 4.6 μm (WISE W1 and W2 or IRAC 1 and 2). In this paper, we derive stellar mass-to-light ratios for these and optical bands, and confirm that the NIR M/L shows dramatically reduced sensitivity to both age and metallicity compared to optical bands, and further, that this behavior leads to significantly more robust stellar masses for quiescent galaxies with [Fe/H] ≳ -0.5 regardless of star-formation history (SFH). We then use realistic early-type galaxy SFHs and metallicity distributions from the EAGLE simulations of galaxy formation to investigate two methods to determine the appropriate M/L for a galaxy. (1) We show that the uncertainties introduced by an unknown SFH can be largely removed using a spectroscopically inferred luminosity-weighted age and metallicity for the population to select the appropriate single stellar population (SSP) equivalent M/L. Using this method, the maximum systematic error due to SFH on the M/L of an early-type galaxy is \\lt 4 % at 3.4 μm and typical uncertainties due to errors in the age and metallicity create a scatter of ≲ 13 % . The equivalent values for optical bands are more than two to three times greater, even before considering uncertainties associated with internal dust extinction. (2) We demonstrate that if the EAGLE SFHs and metallicities accurately reproduce the true properties of early-type galaxies, the use of an iterative approach to select a mass dependent M/L can provide even more accurate stellar masses for early-type galaxies, with typical uncertainties of \\lt 9 % .

  8. The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) III. Construction of the first flux-limited supercluster sample

    CERN Document Server

    Chon, Gayoung; Nowak, Nina

    2012-01-01

    We present the first supercluster catalogue constructed with the extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster survey (REFLEX II) data, which comprises 919 X-ray selected galaxy clusters. Based on this cluster catalogue we construct a supercluster catalogue using a friends-of-friends algorithm with a linking length depending on the local cluster density. The resulting catalogue comprises 164 superclusters at redshift z<=0.4. We study the properties of different catalogues such as the distributions of the redshift, extent and multiplicity by varying the choice of parameters. In addition to the main catalogue we compile a large volume-limited cluster sample to investigate the statistics of the superclusters. We also compare the X-ray luminosity function for the clusters in superclusters with that for the field clusters with the flux- and volume-limited catalogues. The results mildly support the theoretical suggestion of a top-heavy X-ray luminosity function of galaxy clusters in regions of high cluste...

  9. The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) IV. X-ray Luminosity Function and First Constraints on Cosmological Parameters

    CERN Document Server

    Böhringer, H; Collins, C A

    2014-01-01

    The X-ray luminosity function is an important statistic of the census of galaxy clusters and an important means to probe the cosmological model of our Universe. Based on our recently completed REFLEX II cluster sample we construct the X-ray luminosity function of galaxy clusters for several redshift slices from $z = 0$ to $z = 0.4$ and discuss its implications. We find no significant signature of redshift evolution of the luminosity function in the redshift interval. We provide the results of fits of a parameterized Schechter function and extensions of it which provide a reasonable characterization of the data. Using a model for structure formation and galaxy cluster evolution we compare the observed X-ray luminosity function with predictions for different cosmological models. For the most interesting constraints for the cosmological parameters $\\Omega_m$ and $\\sigma_8$ we obatain $\\Omega_m \\sim 0.27 \\pm 0.03$ and $\\sigma_8 \\sim 0.80 \\pm 0.03$ based on the statistical uncertainty alone. Marginalizing over the...

  10. Boosting Lyα and He II λ1640 Line Fluxes from Population III Galaxies: Stochastic IMF Sampling and Departures from Case-B

    Science.gov (United States)

    Mas-Ribas, Lluís; Dijkstra, Mark; Forero-Romero, Jaime E.

    2016-12-01

    We revisit calculations of nebular hydrogen Lyα and He ii λ1640 line strengths for Population III (Pop III) galaxies, undergoing continuous, and bursts of, star formation. We focus on initial mass functions (IMFs) motivated by recent theoretical studies, which generally span a lower range of stellar masses than earlier works. We also account for case-B departures and the stochastic sampling of the IMF. In agreement with previous work, we find that departures from case-B can enhance the Lyα flux by a factor of a few, but we argue that this enhancement is driven mainly by collisional excitation and ionization, and not due to photoionization from the n = 2 state of atomic hydrogen. The increased sensitivity of the Lyα flux to the high-energy end of the galaxy spectrum makes it more subject to stochastic sampling of the IMF. The latter introduces a dispersion in the predicted nebular line fluxes around the deterministic value by as much as a factor of ∼4. In contrast, the stochastic sampling of the IMF has less impact on the emerging Lyman Werner photon flux. When case-B departures and stochasticity effects are combined, nebular line emission from Pop III galaxies can be up to one order of magnitude brighter than predicted by “standard” calculations that do not include these effects. This enhances the prospects for detection with future facilities such as the James Webb Space Telescope and large, ground-based telescopes.

  11. On the Heterogeneity of Metal-Line and Ly-Alpha Absorption in Galaxy "Halos" at z~0.7

    CERN Document Server

    Churchill, C W; Steidel, C C; Evans, J L; Churchill, Christopher W.; Kacprzak, Glenn G.; Steidel, Charles C.; Evans, Jessica L.

    2006-01-01

    We examine the properties of two galaxy "halos" at z ~ 0.7 in the TON 153 (z_em = 1.01) quasar field. The first absorber-galaxy pair (G1) is a z = 0.672, L_B = 4.3 L*_B, E/S0 galaxy probed at D = 58 kpc. G1 is associated with a remarkable five-component Ly-alpha complex having tau_LL < 0.4, W_r(Lya) = 2.8 A, and a velocity spread of v = 1420 km/s. We find no MgII, CIV, NV, nor OVI absorption in these clouds and infer metallicity upper limits of -3 < log(Z/Z_sun) < -1, depending upon assumptions of photoionized or collisionally ionized gas. The second absorber-galaxy pair (G2) is a z = 0.661, L_B = 1.8 L*_B, Sab galaxy probed at D = 103 kpc. G2 is associated with metal--enriched (log Z/Z_sun ~ -0.4) photoionized gas having N(HI) ~ 18.3 and a velocity spread of v = 200 km/s. The very different G1 and G2 systems both have gas-galaxy properties inconsistent with the standard luminosity dependent galaxy "halo" model commonly invoked for quasar absorption line surveys. We emphasize that mounting evidence i...

  12. Metal-poor dwarf galaxies in the SIGRID galaxy sample. II. The electron temperature-abundance calibration and the parameters that affect it

    CERN Document Server

    Nicholls, David C; Sutherland, Ralph S; Jerjen, Helmut; Kewley, Lisa J; Basurah, Hassan

    2014-01-01

    In this paper, we use the Mappings photoionization code to explore the physical parameters that impact on the measurement of electron temperature and abundance in HII regions. In the previous paper we presented observations and measurements of physical properties from the spectra of seventeen HII regions in fourteen isolated dwarf irregular galaxies from the SIGRID sample. Here, we analyze these observations further, together with three additional published data sets. We explore the effects of optical thickness, electron density, ionization parameter, ionization source, and non-equilibrium effects on the relation between electron temperature and metallicity. We present a standard model that fits the observed data remarkably well at metallicities between 1/10 and 1 solar. We investigate the effects of optically thin HII regions, and show that they can have a considerable effect on the measured electron temperature, and that there is evidence that some of the observed objects are optically thin. We look at the ...

  13. Coevolution of metallicity and star formation in galaxies to z=3.7: II. A theoretical model

    CERN Document Server

    Hunt, Leslie; Magrini, Laura; Ferrara, Andrea

    2016-01-01

    Recent work suggests that galaxy evolution, and the build-up of stellar mass (M*) over cosmic time, is characterized by changes with redshift of star formation rate (SFR) and oxygen abundance (O/H). In a companion paper, we have compiled a large dataset to study Metallicity Evolution and Galaxy Assembly (MEGA), consisting of roughly 1000 galaxies to z=3.7 with a common O/H calibration. Here we interpret the MEGA scaling relations of M*, SFR, and O/H with an updated version of the model presented by Dayal et al. (2013). This model successfully reproduces the observed O/H ratio of 80,000 galaxies selected from the Sloan Digital Sky Survey to within 0.05-0.06 dex. By extending the model to the higher redshift MEGA sample, we find that although the specific mass loading of outflows does not change measurably during the evolution, the accretion rate and gas content of galaxies increase significantly with redshift. These two effects can explain, either separately or possibly in tandem, the observed lower metal abun...

  14. The VIPERS Multi-Lambda Survey - II: Diving with massive galaxies in 22 square degrees since z = 1.5

    CERN Document Server

    Moutard, T; Ilbert, O; Coupon, J; Davidzon, I; Guzzo, L; Hudelot, P; McCracken, H J; Van Waerbeke, L; Morrison, G E; Fèvre, O Le; Comte, V; Bolzonella, M; Fritz, A; Garilli, B; Scodeggio, M

    2016-01-01

    We investigate the evolution of the galaxy stellar mass function (SMF) and stellar mass density from redshift z=0.2 to z=1.5 of a $K_{AB}$22.5) samples, respectively. The SMF is measured with ~760,000 galaxies down to $K_s$=22 and over an effective area of ~22.4 deg$^2$, the latter of which drastically reduces the statistical uncertainties (i.e. Poissonian error & cosmic variance). We point out the importance of a careful control of the photometric calibration, whose impact becomes quickly dominant when statistical uncertainties are reduced, which will be a major issue for future generation of cosmological surveys with, e.g. EUCLID or LSST. By exploring the rest-frame (NUV-r) vs (r-$K_s$) color-color diagram separating star-forming and quiescent galaxies, (1) we find that the density of very massive log($M_*/ M_{\\odot}$) > 11.5 galaxies is largely dominated by quiescent galaxies and increases by a factor 2 from z~1 to z~0.2, which allows for additional mass assembly via dry mergers, (2) we confirm a scena...

  15. Formation and evolution of dwarf early-type galaxies in the Virgo cluster II. Kinematic Scaling Relations

    CERN Document Server

    Toloba, E; Peletier, R; Falcon-Barroso, J; van de Ven, G; Gorgas, J

    2012-01-01

    We place our sample of 18 Virgo dwarf early-type galaxies (dEs) on the V-K - velocity dispersion, Faber-Jackson, and Fundamental Plane (FP) scaling relations for massive early-type galaxies (Es). We use a generalized velocity dispersion, which includes rotation, to be able to compare the location of both rotationally and pressure supported dEs with those of early and late-type galaxies. We find that dEs seem to bend the Faber-Jackson relation of Es to lower velocity dispersions, being the link between Es and dwarf spheroidal galaxies (dSphs). Regarding the FP relation, we find that dEs are significantly offset with respect to massive hot stellar systems, and re-casting the FP into the so-called kappa-space suggests that this offset is related to dEs having a total mass-to-light ratio higher than Es but still significantly lower than dSph galaxies. Given a stellar mass-to-light ratio based on the measured line indices of dEs, the FP offset allows us to infer that the dark matter fraction within the half light ...

  16. Using Galaxy Winds to Constrain Galaxy Evolution

    Science.gov (United States)

    Churchill, Christopher W.; Klypin, A.; Ceverino, D.; Kacprzak, G.; Klimek, E.

    2010-01-01

    Analysis of mock quasar spectra of metal absorption lines in the proximity of formed galaxies in cosmological simulation is a highly promising for understanding the role of galaxies in IGM physics, or IGM physics in the role of galaxy formation in context of the cosmic web. Such analysis using neutral hydrogen in the cosmic web has literally revolutionized our understanding of the Lyman alpha forest. We are undertaking a wholesale approach to use powerful Lambda-CDM simulations to interpret absorption line data from redshift 1-3 starbursting galaxies e.g. Lyman break galaxies, etc) The data with which direct quantitative comparison is made are from the DEEP survey (Weiner et al.) and the collective work of Steidel et al. and collaborators. The simulations are performed using the Eulerian Gasdynamics plus N-body Adaptive Refinement Tree (ART) code, which has gas cell resolutions of 20-50 pc. Physical processes implemented in the code include realistic radiative cooling, star formation, metal enrichment and thermal feedback due to type II and type Ia supernovae. We quantitatively compare the spatial and kinematic distribution of HI, MgII, CIV, and OVI of absorption lines over a range of impact parameters for various simulated galaxies as a function of redshift, and discuss key insights for interpreting the underlying temperature, density, and ionization structure of the halo/cosmic-web interface, and the influence of galaxies on its chemical enrichment.

  17. 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...

  18. Large scale star formation in galaxies. II. The spirals NGC 3377A, NGC 3507 and NGC 4394

    CERN Document Server

    Vicari, A; Capuzzo-Dolcetta, R; Wyder, T K; Arrabito, G

    2001-01-01

    The identification of young star groupings (YSG) in the three spiral galaxies NGC 3377A, NGC 3507, NGC 4394 is obtained by mean of the statistical method described in Paper I. We find 83, 90, 185 YSGs, respectively. An identification map of YSGs, as well as their size distribution, their B-luminosity function, their surface luminosity density radial behaviour, are presented and comparatively discussed. These data, in addition to those in Paper I, constitute a first sample suitable for seeking correlations among properties of galaxies and their YSG, which we briefly discuss here.

  19. 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...

  20. The ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) I. Newly identified X-ray luminous clusters at z>=0.2

    CERN Document Server

    Chon, Gayoung

    2011-01-01

    We report 19 intermediate redshift clusters newly detected in the ROSAT All-Sky survey that are spectroscopically confirmed. They form a part of 911 objects in the REFLEX II cluster catalogue with a limiting flux of 1.8\\times10^12 erg/s/cm2 in the 0.1-2.4 keV ROSAT band at redshift z >= 0.2. In addition we report three clusters from the REFLEX III supplementary catalogue, which contains objects below the REFLEX II flux limit but satisfies the redshift constraint above. These clusters are spectroscopically followed-up by our ESO NTT-EFOSC2 campaigns for the redshift measurement. We describe our observing and data reduction methods. We show how X-ray properties such as spectral hardness ratio and source extent can be used as important diagnostics in selecting galaxy cluster candidates. Physical properties of the clusters are subsequently calculated from the X-ray observations. This sample contains the high mass and intermediate-redshift galaxy clusters for astrophysical and cosmological applications.

  1. An ALMA survey of Sub-millimetre Galaxies in the Extended Chandra Deep Field South: Detection of [C II] at z=4.4

    CERN Document Server

    Swinbank, Mark; Smail, Ian; Hodge, Jackie; Walter, Fabian; Bertoldi, Frank; Biggs, Andy; De Breuck, Carlos; Chapman, Scott; Coppin, Kristen; Cox, Pierre; Danielson, Alice; Dannerbauer, Helmut; Ivison, Rob; Greve, Thomas; Knudsen, Kirsten; Menten, Karl; Simpson, James; Schinnerer, Eva; Wardlow, Julie; Weiss, Axel; van der Werf, Paul

    2012-01-01

    We present ALMA 870-um (345GHz) observations of two sub-millimetre galaxies (SMGs) drawn from an ALMA study of the 126 sub-millimeter sources from the LABOCA Extended Chandra Deep Field South Survey (LESS). The ALMA data identify the counterparts to these previously unidentified sub-millimeter sources and serendipitously detect bright emission lines in their spectra which we show are most likely to be [C II]157.74um emission yielding redshifts of z=4.42 and z=4.44. This blind detection rate within the 7.5-GHz bandpass of ALMA is consistent with the previously derived photometric redshift distribution of SMGs and suggests a modest, but not dominant (4. We find that the ratio of L_CII/L_FIR in these SMGs is much higher than seen for similarly far-infrared-luminous galaxies at z~0, which is attributed to the more extended gas reservoirs in these high-redshift ULIRGs. Indeed, in one system we show that the [C II] emission shows hints of extended emission on >3kpc scales. Finally, we use the volume probed by our A...

  2. 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

  3. 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

  4. Being WISE II: Reducing the Influence of Star Formation History on the Mass-to-Light Ratio of Quiescent Galaxies

    CERN Document Server

    Norris, Mark A; Schinnerer, Eva; Crain, Robert A; Meidt, Sharon; Groves, Brent; Bower, Richard G; Furlong, Michelle; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-01-01

    Stellar population synthesis models can now reproduce the photometry of old stellar systems (age $>$ 2 Gyr) in the near-infrared (NIR) bands at 3.4 and 4.6$\\mu$m (WISE W1 $\\&$ W2 or IRAC 1 $\\&$ 2). In this paper we derive stellar mass-to-light ratios for these and optical bands, and confirm that the NIR M/L shows dramatically reduced sensitivity to both age and metallicity compared to optical bands, and further, that this behavior leads to significantly more robust stellar masses for quiescent galaxies with [Fe/H] > -0.5 regardless of star formation history (SFH). We then use realistic early-type galaxy SFHs and metallicity distributions from the EAGLE simulations of galaxy formation to investigate two methods to determine the appropriate M/L for a galaxy: 1) We show that the uncertainties introduced by an unknown SFH can be largely removed using a spectroscopically inferred luminosity-weighted age and metallicity for the population to select the appropriate single stellar population (SSP) equivalent ...

  5. The Interstellar Medium and Star Formation in Edge-On Galaxies. II. NGC 4157, 4565, and 5907

    NARCIS (Netherlands)

    Yim, Kijeong; Wong, Tony; Xue, Rui; Rand, Richard J.; Rosolowsky, Erik; van der Hulst, J. M.; Benjamin, Robert; Murphy, Eric J.

    2014-01-01

    We present a study of the vertical structure of the gaseous and stellar disks in a sample of edge-on galaxies (NGC 4157, 4565, and 5907) using BIMA/CARMA 12COJ=1\\to 0, VLA Hi, and Spitzer 3.6 μm data. In order to take into account projection effects when we measure the disk thickness as a function

  6. A CFH12k lensing survey of X-ray luminous galaxy clusters - II. Weak lensing analysis and global correlations

    NARCIS (Netherlands)

    Bardeau, S.; Soucail, G.; Kneib, J.-P.; Czoske, O.; Ebeling, H.; Hudelot, P.; Smail, I.; Smith, G. P.

    2007-01-01

    Aims. We present a wide-field multi-color survey of a homogeneous sample of eleven clusters of galaxies for which we measure total masses and mass distributions from weak lensing. This sample, spanning a small range in both X-ray luminosity and redshift, is ideally suited to determining the normalis

  7. Tracing Galaxy Formation with Stellar Halos. II. Relating Substructure in Phase and Abundance Space to Accretion Histories

    Science.gov (United States)

    Johnston, Kathryn V.; Bullock, James S.; Sharma, Sanjib; Font, Andreea; Robertson, Brant E.; Leitner, Samuel N.

    2008-12-01

    This paper explores the mapping between the observable properties of a stellar halo in phase and abundance space and the parent galaxy's accretion history in terms of the characteristic epoch of accretion and mass and orbits of progenitor objects. The study utilizes a suite of 11 stellar halo models constructed within the context of a standard ΛCDM cosmology. The results demonstrate that coordinate-space studies are sensitive to the recent (0-8 Gyr ago) merger histories of galaxies (this timescale corresponds to the last few percent to tens of percent of mass accretion for a Milky Way-type galaxy). Specifically, the frequency, sky coverage, and fraction of stars in substructures in the stellar halo as a function of surface brightness are indicators of the importance of recent merging and of the luminosity function of infalling dwarfs. The morphology of features serves as a guide to the orbital distribution of those dwarfs. Constraints on the earlier merger history (>8 Gyr ago) can be gleaned from the abundance patterns in halo stars: within our models, dramatic differences in the dominant epoch of accretion or luminosity function of progenitor objects leave clear signatures in the [α/Fe] and [Fe/H] distributions of the stellar halo; halos dominated by very early accretion have higher average [α/Fe], while those dominated by high-luminosity satellites have higher [Fe/H]. This insight can be applied to reconstruct much about the merger histories of nearby galaxies from current and future data sets.

  8. NIHAO project II: Halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations

    CERN Document Server

    Butsky, Iryna; Dutton, Aaron A; Wang, Liang; Stinson, Greg S; Penzo, Camilla; Kang, Xi; Keller, Ben W; Wadsley, James

    2015-01-01

    We show the effect of galaxy formation on the dark matter (DM) distribution across a wide range of halo masses. We focus on how baryon physics changes the dark matter halo shape, the so called "pseudo phase-space density distribution" and the velocity distribution within the virial radius, Rvir and in the solar neighborhood. This study is based on the NIHAO galaxy formation simulations, a large suite of cosmological zoom-in simulations. The galaxies reproduce key properties of observed galaxies, and hence offer unique insight into how baryons change the dark matter morphology and kinematics. When compared to dark matter only simulations, the NIHAO haloes have similar shapes at Rvir, but are substantially rounder inside ~0.1 Rvir. In DM-only simulations the inner halo has a minor-to-major axis ratio of c/a~0.5. In hydro simulations c/a increases with halo mass and integrated star formation efficiency, reaching ~0.8 at the Milky Way mass, reconciling a long-standing conflict between observations and DM only sim...

  9. The sloan lens acs survey. II. Stellar populations and internal structure of early-type lens galaxies

    NARCIS (Netherlands)

    Treu, Tommaso; Koopmans, Léon V.; Bolton, Adam S.; Burles, Scott; Moustakas, Leonidas A.

    2006-01-01

    We use HST images to derive effective radii and effective surface brightnesses of 15 early-type (E+S0) lens galaxies identified by the SLACS Survey. Our measurements are combined with stellar velocity dispersions from the SDSS database to investigate for the first time the distribution of lens galax

  10. Lyman break and UV-selected galaxies at z ~ 1: II. PACS-100um/160um FIR detections

    CERN Document Server

    Oteo, I; Bongiovanni, Á; Pérez-García, A M; Cepa, J; Cedrés, B; Ederoclite, A; Sánchez-Portal, M; Aguerri, J A L; Alfaro, E J; Altieri, B; Andreani, P; Aparicio-Villegas, T; Aussel, H; itez, N Ben\\'; Berta, S; Broadhurst, T; Cabrera-Caño, J; Castander, F J; Cerviño, M; Cimatti, A; Cristobal-Hornillos, D; Daddi, E; Elbaz, D; Fernandez-Soto, A; Schreiber, N Förster; Genzel, R; Gonzalez-Delgado, R M; Husillos, C; Infante, L; Floc'h, E Le; Lutz, D; Magnelli, B; Maiolino, R; arquez, I M\\'; inez, V J Mart\\'; Masegosa, J; Matute, I; Moles, M; Molino, A; del Olmo, A; Perea, J; inez, R P\\' erez-Mart\\'; Pintos-Castro, I; Poglitsch, A; Polednikova, J; Popesso, P; Pović, M; Pozzi, F; Prada, F; Quintana, J M; Riguccini, L; Sturm, E; Tacconi, L; Valtchanov, I; Viironen, K

    2013-01-01

    We report the PACS-100um/160um detections of a sample of 42 GALEX-selected and FIR-detected Lyman break galaxies (LBGs) at z ~ 1 located in the COSMOS field and analyze their ultra-violet (UV) to far-infrared (FIR) properties. The detection of these LBGs in the FIR indicates that they have a dust content high enough so that its emission can be directly detected. According to a spectral energy distribution (SED) fitting with stellar population templates to their UV-to-near-IR observed photometry, PACS-detected LBGs tend to be bigger, more massive, dustier, redder in the UV continuum, and UV-brighter than PACS-undetected LBGs. PACS-detected LBGs at z ~ 1 are mostly disk-like galaxies and are located over the green-valley and red sequence of the color-magnitude diagram of galaxies at their redshift. By using their UV and IR emission, we find that PACS-detected LBGs tend to be less dusty and have slightly higher total star-formation rates (SFRs) than other PACS-detected UV-selected galaxies within their same reds...

  11. The star cluster - field star connection in nearby spiral galaxies. II. Field star and cluster formation histories and their relation

    NARCIS (Netherlands)

    Silva-Villa, E.; Larsen, S.S.

    2011-01-01

    Context. Recent studies have started to cast doubt on the assumption that most stars are formed in clusters. Observational studies of field stars and star cluster systems in nearby galaxies can lead to better constraints on the fraction of stars forming in clusters. Ultimately this may lead to a bet

  12. A Multiwavelength Study of a Sample of 70 micron Selected Galaxies in the COSMOS Field II: The Role of Mergers in Galaxy Evolution

    CERN Document Server

    Kartaltepe, Jeyhan S; Le Floc'h, E; Frayer, D T; Aussel, H; Arnouts, S; Ilbert, O; Salvato, M; Scoville, N Z; Surace, J; Yan, L; Capak, P; Caputi, K; Carollo, C M; Cassata, P; Civano, F; Hasinger, G; Koekemoer, A M; Le Fèvre, O; Lilly, S; Liu, C T; McCracken, H J; Schinnerer, E; Smolcic, V; Taniguchi, Y; Thompson, D J; Trump, J; Baldassare, V F; Fiorenza, S L

    2010-01-01

    We analyze the morphological properties of a large sample of 1503 70 micron selected galaxies in the COSMOS field spanning the redshift range 0.011 being difficult to classify and subject to the effects of band pass shifting, therefore, these numbers can only be considered lower limits. At z1 the fraction of major mergers is at least 30-40% for ULIRGs. Although the general morphological trends agree with what has been observed for local (U)LIRGs, the fraction of major mergers is slightly lower than seen locally. This is in part due to the difficulty of identifying merger signatures at high redshift. W e argue that given the number of major gas-rich mergers observed and the relatively short timescale that they would be observable in the (U)LIRG phase that it is plausible for the observed red sequence of massive ellipticals (<10^12 M_sun) to have been formed entirely by gas-rich major mergers.

  13. The galaxy counterpart of the high-metallicity and 16 kpc impact parameter DLA towards Q 0918+1636 - a challenge to galaxy formation models?

    Science.gov (United States)

    Sommer-Larsen, J.; Fynbo, J. P. U.

    2017-01-01

    The quasar Q0918+1636 (z = 3.07) has an intervening high-metallicity damped Lyman α absorber (DLA) along the line of sight, at a redshift of z = 2.58. The DLA is located at a large impact parameter of 16.2 kpc, and despite this large impact parameter, it has a very high metallicity (consistent with solar). In this paper, it is investigated whether a novel type of galaxy formation models, based on hydrodynamical/gravitational TreeSPH simulations invoking a new Supernova Type II feedback prescription, the Haardt & Madau most recent ultraviolet background radiation (UVB) field and explicit treatment of UVB self-shielding effects, can reproduce the observed characteristics of the DLA. Effects of UV radiation from young stellar populations in the galaxy, in particular in the photon energy range 10.36-13.61 eV (relating to Sulphur II abundance), are also considered in the analysis. It is found that (a) for L ˜ L⋆ galaxies (at z = 2.58), about 10 per cent of the sight-lines through the galaxies at impact parameter b = 16.2 kpc will display a Sulphur II column density of N({S II)} ≥ 10^{15.82} cm-2 (the observed value for the DLA), and (b) considering only cases where a near-solar metallicity will be detected at 16.2 kpc impact parameter, the (Bayesian) probability distribution of galaxy star formation rate peaks near the value observed for the DLA galaxy counterpart of 27^{+20}_{-9} { M_{⊙}} yr-1. It is argued that the bulk of the α-elements, like Sulphur, traced by the high metal column density, b = 16.2 kpc absorption lines, have been produced by evolving stars in the inner galaxy, and subsequently transported outwards by galactic winds.

  14. The star cluster - field star connection in nearby spiral galaxies. II. Field star and cluster formation histories and their relation

    Science.gov (United States)

    Silva-Villa, E.; Larsen, S. S.

    2011-05-01

    Context. Recent studies have started to cast doubt on the assumption that most stars are formed in clusters. Observational studies of field stars and star cluster systems in nearby galaxies can lead to better constraints on the fraction of stars forming in clusters. Ultimately this may lead to a better understanding of star formation in galaxies, and galaxy evolution in general. Aims: We aim to constrain the amount of star formation happening in long-lived clusters for four galaxies through the homogeneous, simultaneous study of field stars and star clusters. Methods: Using HST/ACS and HST/WFPC2 images of the galaxies NGC 45, NGC 1313, NGC 5236, and NGC 7793, we estimate star formation histories by means of the synthetic CMD method. Masses and ages of star clusters are estimated using simple stellar population model fitting. Comparing observed and modeled luminosity functions, we estimate cluster formation rates. By randomly sampling the stellar initial mass function (SIMF), we construct artificial star clusters and quantify how stochastic effects influence cluster detection, integrated colors, and age estimates. Results: Star formation rates appear to be constant over the past 107 - 108 years within the fields covered by our observations. The number of clusters identified per galaxy varies, with a few detected massive clusters (M ≥ 105 M⊙) and a few older than 1 Gyr. Among our sample of galaxies, NGC 5236 and NGC 1313 show high star and cluster formation rates, while NGC 7793 and NGC 45 show lower values. We find that stochastic sampling of the SIMF has a strong impact on the estimation of ages, colors, and completeness for clusters with masses ≤ 103 - 104 M⊙, while the effect is less pronounced for high masses. Stochasticity also makes size measurements highly uncertain at young ages (τ ≲ 108 yr), making it difficult to distinguish between clusters and stars based on sizes. Conclusions: The ratio of star formation happening in clusters (Γ) compared to

  15. GAS SURFACE DENSITY, STAR FORMATION RATE SURFACE DENSITY, AND THE MAXIMUM MASS OF YOUNG STAR CLUSTERS IN A DISK GALAXY. II. THE GRAND-DESIGN GALAXY M51

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Lopezlira, Rosa A. [On sabbatical leave from the Centro de Radioastronomia y Astrofisica, UNAM, Campus Morelia, Michoacan, C.P. 58089, Mexico. (Mexico); Pflamm-Altenburg, Jan; Kroupa, Pavel, E-mail: r.gonzalez@crya.unam.mx [Argelander Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany)

    2013-06-20

    We analyze the relationship between maximum cluster mass and surface densities of total gas ({Sigma}{sub gas}), molecular gas ({Sigma}{sub H{sub 2}}), neutral gas ({Sigma}{sub H{sub I}}), and star formation rate ({Sigma}{sub SFR}) in the grand-design galaxy M51, using published gas data and a catalog of masses, ages, and reddenings of more than 1800 star clusters in its disk, of which 223 are above the cluster mass distribution function completeness limit. By comparing the two-dimensional distribution of cluster masses and gas surface densities, we find for clusters older than 25 Myr that M{sub 3rd}{proportional_to}{Sigma}{sub H{sub I}{sup 0.4{+-}0.2}}, whereM{sub 3rd} is the median of the five most massive clusters. There is no correlation with{Sigma}{sub gas},{Sigma}{sub H2}, or{Sigma}{sub SFR}. For clusters younger than 10 Myr, M{sub 3rd}{proportional_to}{Sigma}{sub H{sub I}{sup 0.6{+-}0.1}} and M{sub 3rd}{proportional_to}{Sigma}{sub gas}{sup 0.5{+-}0.2}; there is no correlation with either {Sigma}{sub H{sub 2}} or{Sigma}{sub SFR}. The results could hardly be more different from those found for clusters younger than 25 Myr in M33. For the flocculent galaxy M33, there is no correlation between maximum cluster mass and neutral gas, but we have determined M{sub 3rd}{proportional_to}{Sigma}{sub gas}{sup 3.8{+-}0.3}, M{sub 3rd}{proportional_to}{Sigma}{sub H{sub 2}{sup 1.2{+-}0.1}}, and M{sub 3rd}{proportional_to}{Sigma}{sub SFR}{sup 0.9{+-}0.1}. For the older sample in M51, the lack of tight correlations is probably due to the combination of strong azimuthal variations in the surface densities of gas and star formation rate, and the cluster ages. These two facts mean that neither the azimuthal average of the surface densities at a given radius nor the surface densities at the present-day location of a stellar cluster represent the true surface densities at the place and time of cluster formation. In the case of the younger sample, even if the clusters have not yet

  16. Posterior C1-C2 Fixation Using Absorbable Suture for Type II Odontoid Fracture in 2-Year-Old Child: Description of a New Technique and Literature Review.

    Science.gov (United States)

    Labbe, Jean L; Peres, Olivier; Leclair, Olivier; Goulon, Renaud; Scemama, Patrice; Jourdel, François; Bertrou, Véronique; Murgier, Jerome

    2016-12-01

    Odontoid synchondrosis fractures are rare in children, even though they are the more common cervical fracture in children less than 7 years old. Nonoperative treatment with external orthosis immobilization is the treatment of choice for stable undisplaced or minimally displaced injuries. In unstable fractures, when reduction cannot be achieved or maintained, surgical fixation is recommended. We report a 2-year-old boy with an unstable fracture of the odontoid treated surgically using an absorbable monofilament suture for C1-C2 interlaminar fixation without bone grafting. This suture was strong enough to provide the stability necessary to allow healing of the synchondrosis and the delayed resorption of the suture was followed by complete restoration of the mobility between C1 and C2. This case illustrates that surgical stabilization using an absorbable suture in young children with an unstable odontoid fracture is a safe and effective alternative to other surgical techniques.

  17. Tracing Outflows and Accretion: A Bimodal Azimuthal Dependence of MgII Absorption

    CERN Document Server

    Kacprzak, G G; Nielsen, N M

    2012-01-01

    We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by MgII absorption: Halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed MgII absorption-selected galaxies [W_r(2796)> 0.1A] and 35 spectroscopically confirmed non-absorbing galaxies [W_r(2796)<0.1A] imaged with HST and SDSS. The azimuthal angle distribution for non-absorbers is flat, indicating no azimuthal preference for gas characterized by W_r(2796)<0.1A. We find that blue star-forming galaxies clearly drive the bimodality. We compute an azimuthal angle dependent MgII absorption covering fraction and find that it is enhanced by as much as 20-30% along the major and minor axes. The equivalent width distribution for gas along the major axis is likely skewed toward weaker MgII absorption than for gas along the projected minor axis. These combined results...

  18. Characterizing the Chemically-Enriched Circumgalactic Medium of ~38000 Luminous Red Galaxies in SDSS DR12

    CERN Document Server

    Huang, Yun-Hsin; Johnson, Sean D; Weiner, Benjamin J

    2015-01-01

    We report a definitive detection of chemically-enriched cool gas around massive, quiescent galaxies at z~0.4-0.7. The result is based on a survey of 37621 luminous red galaxy (LRG)-QSO pairs in SDSS DR12 with projected distance d~1Gyr) stellar population with 13% displaying [OII] emission features and LINER-like spectra. Both passive and [OII]-emitting LRGs share the same stellar mass distribution with a mean of ~11.4 and a dispersion of 0.2 dex. Both LRG populations exhibit associated strong MgII absorbers out to d_MgII > 15% and declines quickly to _MgII ~ 5% at d_MgII around passive LRGs at all radii, a modest enhancement in _MgII is detected along the major axis of [OII]-emitting LRGs at d_MgII along the major axis of [OII]-emitting LRGs at d<50 kpc, provides important insights into the origin of the observed chemically-enriched cool gas in LRG halos. We consider different scenarios and conclude that the observed MgII absorbers around LRGs are best-explained by a combination of cool clouds formed in th...

  19. A radial velocity survey of low Galactic latitude structures: II. The Monoceros Ring behind the Canis Major dwarf galaxy

    CERN Document Server

    Conn, B C; Lewis, G F; Ibata, R A; Bellazzini, M; Irwin, M J; Conn, Blair C.; Martin, Nicolas F.; Lewis, Geraint F.; Ibata, Rodrigo A.; Bellazzini, Michele; Irwin, Mike J.

    2005-01-01

    An AAT/2dF Spectrograph Survey of low Galactic latitudes targeting the putative Canis Major dwarf galaxy, and the (possibly) associated tidal debris of stars known as the Monoceros Ring, covering Galactic coordinates 231.5$^{\\circ}< ${\\it l} $<$ 247.5$^{\\circ}$ and -11.8$^{\\circ}<${\\it b}$<-3.8^{\\circ}$, has revealed the presence of the Monoceros Ring in the background of the Canis Major dwarf galaxy. This detection resides at a galactocentric distance of $\\sim18.9\\pm$0.3\\kpc (13.5$\\pm$0.3\\kpc heliocentric), exhibiting a velocity of $\\sim132.8\\pm$1.3 $\\kms$ with a dispersion of $\\sim22.7\\pm1.7\\kms$; both of these comparable with previous measurements of the Monoceros Ring in nearby fields. This detection highlights the increasing complexity of structure being revealed in recent surveys of the Milky Way thick disk and Halo.

  20. Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564. II. Ultraviolet Continuum and Emission-line Variability

    CERN Document Server

    Collier, S J; Peterson, B M; Brandt, W N; Clavel, J; Edelson, R; George, I M; Horne, K; Kriss, G A; Mathur, S; Netzer, H; O'Brien, P T; Pogge, R W; Pounds, K A; Romano, P; Shemmer, O; Turner, T J; Wamsteker, W

    2001-01-01

    We present results of an intensive two-month campaign of approximately daily spectrophotometric monitoring of the narrow-line Seyfert 1 galaxy Akn 564 with HST. The fractional variability amplitude of the continuum variations between 1365-3000 A is ~6%, about a factor 3 less than that found in typical Seyfert 1 galaxies over a similar period of time. However, large amplitude, short time-scale flaring behavior is evident, with trough-to-peak flux changes of about 18% in approximately 3 days. We present evidence for wavelength-dependent continuum time delays, with the variations at 3000 A lagging behind those at 1365 A by about 1 day. These delays may be interpreted as evidence for a stratified continuum reprocessing region, possibly an accretion-disk structure. The Lyman-alpha 1216 emission-line exhibits flux variations of about 1% amplitude.

  1. MEASURING STAR FORMATION RATES AND FAR-INFRARED COLORS OF HIGH-REDSHIFT GALAXIES USING THE CO(7–6) AND [N II] 205 μm LINES

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Nanyao; Zhao, Yinghe; Xu, C. Kevin; Howell, Justin; Mazzarella, Joseph M.; Schulz, Bernhard [Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States); Gao, Yu; Liu, Lijie [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Díaz-Santos, Tanio; Armus, Lee [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States); Charmandaris, Vassilis [Department of Physics, University of Crete, GR-71003 Heraklion (Greece); Inami, Hanae [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Privon, George C. [Departamento de Astronomía, Universidad de Concepción, Casilla 160 C, Concepción (Chile); Lord, Steven D. [The SETI Institute, 189 Bernardo Avenue Suite 100, Mountain View, CA 94043 (United States); Sanders, David B. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Van der Werf, Paul P., E-mail: lu@ipac.caltech.edu [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

    2015-03-20

    To better characterize the global star formation activity in a galaxy, one needs to know not only the star formation rate (SFR) but also the rest-frame, far-infrared color (e.g., the 60–100 μm color, C(60/100)) of the dust emission. The latter probes the average intensity of the dust heating radiation field and scales statistically with the effective SFR surface density in star-forming galaxies including (ultra-)luminous infrared galaxies ((U)LIRGs). To this end, here we exploit a new spectroscopic approach involving only two emission lines: CO(7–6) at 372 μm and [N ii] at 205 μm([N ii]{sub 205μm}). For local (U)LIRGs, the ratios of the CO(7–6) luminosity (L{sub CO(7–6)}) to the total infrared luminosity (L{sub IR}; 8–1000 μm) are fairly tightly distributed (to within ∼0.12 dex) and show little dependence on C(60/100). This makes L{sub CO(7–6)} a good SFR tracer, which is less contaminated by active galactic nuclei than L{sub IR} and may also be much less sensitive to metallicity than L{sub CO(1–0)}. Furthermore, the logarithmic [N ii]{sub 205μm}/CO(7–6) luminosity ratio depends fairly strongly (at a slope of ∼ −1.4) on C(60/100), with a modest scatter (∼0.23 dex). This makes it a useful estimator on C(60/100) with an implied uncertainty of ∼0.15 (or ≲4 K in the dust temperature (T{sub dust}) in the case of a graybody emission with T{sub dust} ≳ 30 K and a dust emissivity index β ≥ 1). Our locally calibrated SFR and C(60/100) estimators are shown to be consistent with the published data of (U)LIRGs of z up to ∼6.5.

  2. Cross-correlation Weak Lensing of SDSS galaxy Clusters II: Cluster Density Profiles and the Mass--Richness Relation

    CERN Document Server

    Johnston, David E; Wechsler, Risa H; Rozo, Eduardo; Koester, Benjamin P; Frieman, Joshua A; McKay, Timothy A; Evrard, August E; Becker, Matthew R; Annis, James

    2007-01-01

    We interpret and model the statistical weak lensing measurements around 130,000 groups and clusters of galaxies in the Sloan Digital Sky Survey presented by Sheldon et al. 2007 (Paper I). We present non-parametric inversions of the 2D shear profiles to the mean 3D cluster density and mass profiles in bins of both optical richness and cluster i-band luminosity. We correct the inferred 3D profiles for systematic effects, including non-linear shear and the fact that cluster halos are not all precisely centered on their brightest galaxies. We also model the measured cluster shear profile as a sum of contributions from the brightest central galaxy, the cluster dark matter halo, and neighboring halos. We infer the relations between mean cluster virial mass and optical richness and luminosity over two orders of magnitude in cluster mass; the virial mass at fixed richness or luminosity is determined with a precision of 13% including both statistical and systematic errors. We also constrain the halo concentration para...

  3. The dark matter halo shape of edge-on disk galaxies - II. Modelling the HI observations: methods

    CERN Document Server

    O'Brien, J C; van der Kruit, P C

    2010-01-01

    This is the second paper of a series in which we attempt to put constraints on the flattening of dark halos in disk galaxies. For this purpose, we observe the HI in edge-on galaxies, where it is in principle possible to measure the force field in the halo vertically and radially from gas layer flaring and rotation curve decomposition respectively. To calculate the force fields, we need to analyse the observed XV diagrams to accurately measure all three functions that describe the planar kinematics and distribution of a galaxy: the radial HI surface density, the rotation curve and the HI velocity dispersion. In this paper, we discuss the improvements and limitations of the methods previously used to measure these HI properties. We extend the constant velocity dispersion method to include determination of the HI velocity dispersion as a function of galactocentric radius and perform extensive tests on the quality of the fits. We will apply this 'radial decomposition XV modelling method' to our HI observations of...

  4. Structure and dynamics of galaxies with a low surface-brightness disc - II. Stellar populations of bulges

    CERN Document Server

    Morelli, L; Pizzella, A; Bontà, E Dalla; Coccato, L; Méndez-Abreu, J; Cesetti, M

    2012-01-01

    The radial profiles of the Hb, Mg, and Fe line-strength indices are presented for a sample of eight spiral galaxies with a low surface-brightness stellar disc and a bulge. The correlations between the central values of the line-strength indices and velocity dispersion are consistent to those known for early-type galaxies and bulges of high surface-brightness galaxies. The age, metallicity, and alpha/Fe enhancement of the stellar populations in the bulge-dominated region are obtained using stellar population models with variable element abundance ratios. Almost all the sample bulges are characterized by a young stellar population, on-going star formation, and a solar alpha/Fe enhancement. Their metallicity spans from high to sub-solar values. No significant gradient in age and alpha/Fe enhancement is measured, whereas only in a few cases a negative metallicity gradient is found. These properties suggest that a pure dissipative collapse is not able to explain formation of all the sample bulges and that other ph...

  5. Deep spectroscopy of z~1 6C radio galaxies - II. Breaking the redshift-radio power degeneracy

    CERN Document Server

    Inskip, K J; Röttgering, H J A; Rawlings, S; Cotter, G; Longair, M S

    2002-01-01

    The results of a spectroscopic analysis of 3CR and 6C radio galaxies at redshift z~1 are contrasted with the properties of lower redshift radio galaxies, chosen to be matched in radio luminosity to the 6C sources studied at z~1, thus enabling the P-z degeneracy to be broken. Partial rank correlations and principal component analysis have been used to determine which of z and P are the critical parameters underlying the observed variation of the ionization state andd kinematics of the emission line gas. [OII]/H-beta is shown to be a useful ionization mechanism diagnostic. Statistical analysis of the data shows that the ionization state of the emission line gas is strongly correlated with radio power, once the effects of other parameters are removed. No dependence of ionization state on z is observed, implying that the ionization state of the emission line gas is solely a function of the AGN properties rather than the hostt galaxy and/or environment. Statistical analysis of the kinematic properties of the emiss...

  6. The star cluster - field star connection in nearby spiral galaxies. II. Field star and cluster formation histories and their relation

    CERN Document Server

    Silva-Villa, Esteban

    2011-01-01

    Recent studies have started to cast doubt on the assumption that most stars are formed in clusters. Observational studies of field stars and star cluster systems in nearby galaxies can lead to better constraints on the fraction of stars forming in clusters. We aim to constrain the amount of star formation happening in long-lived clusters for four galaxies through the homogeneous study of field stars and star clusters. Using HST/ACS-WFPC2 images of the galaxies NGC45, NGC1313, NGC5236 and NGC7793, we estimate star formation histories by means of the synthetic CMD method. Masses and ages of star clusters are estimated using simple stellar population model fitting. Comparing observed and modeled luminosity functions we estimate cluster formation rates. By randomly sampling the stellar IMF, we construct artificial star clusters and quantify how stochastic effects influence cluster detection, integrated colors and age estimates. Star formation rates appear to be constant over the past 10-100 Myr. The number of clu...

  7. The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent : Part II. the regeneration of copper sulfide to copper oxide - An experimental study

    NARCIS (Netherlands)

    Ter Maat, H.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    Aim of this study was to investigate the possibilities for a selective and efficient method to convert copper(II) sulfide (CuS) into copper(II) oxide (CuO). The oxidation of copper sulfide has been studied experimentally using a thermogravimetric analyzer (TGA) at temperatures ranging from 450 to 75

  8. The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent: Part II. The regeneration of copper sulfide to copper oxide—an experimental study

    NARCIS (Netherlands)

    Maat, ter H.; Hogendoorn, J.A.; Versteeg, G.F.

    2005-01-01

    Aim of this study was to investigate the possibilities for a selective and efficient method to convert copper(II) sulfide (CuS) into copper(II) oxide (CuO). The oxidation of copper sulfide has been studied experimentally using a thermogravimetric analyzer (TGA) at temperatures ranging from 450 to 75

  9. The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent : Part II. the regeneration of copper sulfide to copper oxide - An experimental study

    NARCIS (Netherlands)

    Ter Maat, H.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    Aim of this study was to investigate the possibilities for a selective and efficient method to convert copper(II) sulfide (CuS) into copper(II) oxide (CuO). The oxidation of copper sulfide has been studied experimentally using a thermogravimetric analyzer (TGA) at temperatures ranging from 450 to

  10. Nonlinear Color--Metallicity Relations of Globular Clusters. VI. On Calcium II Triplet Based Metallicities of Globular Clusters in Early-type Galaxies

    CERN Document Server

    Chung, Chul; Lee, Sang-Yoon; Lee, Young-Wook

    2016-01-01

    The metallicity distribution function of globular clusters (GCs) in galaxies is a key to understanding galactic formation and evolution. The calcium II triplet (CaT) index has recently become a popular metal abundance indicator thanks to its sensitivity to GC metallicity. Here we revisit and assess the reliability of CaT as a metallicity indicator using our new stellar population synthesis simulations based on empirical, high-resolution fluxes. The model shows that the CaT strength of old ($>$ 10 Gyr) GCs is proportional to ${\\rm [Fe/H]}$ below $-0.5$. In the modest metal-rich regime, however, CaT does not increase anymore with ${\\rm [Fe/H]}$ due to the little contribution from coolest red giant stars to the CaT absorption. The nonlinear nature of the color--$CaT$ relation is confirmed by the observations of GCs in nearby early-type galaxies. This indicates that the CaT should be used carefully when deriving metallicities of metal-rich stellar populations. Our results offer an explanation for the observed sha...

  11. The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II) VI. Effect of massive neutrinos on the cosmological constraints from clusters

    CERN Document Server

    Boehringer, Hans

    2015-01-01

    Clusters of galaxies are important probes for the large-scale structure that allow us to test cosmological models. With the REFLEX II galaxy cluster survey we previously derived tight constraints on the cosmological parameters for the matter density, Omega_m, and the amplitude parameter of the matter density fluctuations, sigma_8. Whereas in these previous studies no effect of massive neutrinos was taken into account, we explore these effects in the present publication. We derive cosmological constraints for the sum of the neutrino masses of the conventional three neutrino families in the range 0 to 0.6 eV. The influence on the constraints of Omega_m and sigma_8 for the expected mass range is weak. Interesting constraints on the neutrino properties can be derived by comparing the cluster data with those from the Planck cosmic microwave background observations. The current tension between the Planck results and clusters can formally be resolved with neutrino masses of about M_nu = 0.45 (+- 0.28, 1-sigma) eV. W...

  12. Boosting Lya and HeII 1640A Line Fluxes from Pop III Galaxies: Stochastic IMF Sampling and Departures from Case-B

    CERN Document Server

    Mas-Ribas, Lluís; Forero-Romero, Jaime E

    2016-01-01

    We revisit calculations of nebular hydrogen Lya and HeII 1640A line strengths for population III galaxies, undergoing continuous and bursts of star formation. We focus on initial mass functions (IMFs) motivated by recent theoretical studies, which generally span a lower range of stellar masses than earlier works. We also account for case-B departures and the stochastic sampling of the IMF. In agreement with previous works, we find that departures from case-B can enhance the Lya flux by a factor of a few, but we argue that this enhancement is driven mainly by collisional excitation and ionization, and not due to photoionization from the n = 2 state of atomic hydrogen. The increased sensitivity of the Lya flux to the high-energy end of the galaxy spectrum makes it more subject to stochastic sampling of the IMF. The latter introduces a dispersion in the predicted nebular line fluxes around the deterministic value by as much as a factor of ~4. In contrast, the stochastic sampling of the IMF has less impact on the...

  13. 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...

  14. He II emitters in the VIMOS VLT Deep Survey: Population III star formation or peculiar stellar populations in galaxies at 2 < z < 4.6?

    Science.gov (United States)

    Cassata, P.; Le Fèvre, O.; Charlot, S.; Contini, T.; Cucciati, O.; Garilli, B.; Zamorani, G.; Adami, C.; Bardelli, S.; Le Brun, V.; Lemaux, B.; Maccagni, D.; Pollo, A.; Pozzetti, L.; Tresse, L.; Vergani, D.; Zanichelli, A.; Zucca, E.

    2013-08-01

    Aims: The aim of this work is to identify He II emitters at 2 Methods: We assembled a sample of 277 galaxies with a highly reliable spectroscopic redshift at 2 1200 km s-1), 3 active galactic nuclei (AGN), and an additional 12 possible He II emitters. The properties of the individual broad emitters are in agreement with expectations from a Wolf-Rayet (W-R) model. Instead, the properties of the narrow emitters are not compatible with this model, nor with predictions of gravitational cooling radiation produced by gas accretion, unless this is severely underestimated by current models by more than two orders of magnitude. Rather, we find that the EW of the narrow He II line emitters are in agreement with expectations for a Population III (PopIII) star formation, if the episode of star formation is continuous, and we calculate that a PopIII star formation rate (SFR) of 0.1-10 M⊙ yr-1 alone is enough to sustain the observed He II flux. Conclusions: We conclude that narrow He II emitters are powered either by the ionizing flux from a stellar population rare at z ~ 0 but much more common at z ~ 3, or by PopIII star formation. As proposed by Tornatore and collaborators, incomplete interstellar medium mixing may leave some small pockets of pristine gas at the periphery of galaxies from which PopIII may form, even down to z ~ 2 or lower. If this interpretation is correct, we measure at z ~ 3 a star formation rate density in PopIII stars of 10-6 M⊙ yr-1 Mpc-3, higher than, but qualitatively comparable to the value predicted by Tornatore and collaborators. Figures 2-8, and 12 are available in electronic form at http://www.aanda.orgBased on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Programs 070.A-9007 and 177.A-0837. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of

  15. An optical spectroscopic survey of the 3CR sample of radio galaxies with z < 0.3. V. Implications for the unified model for FR IIs

    Science.gov (United States)

    Baldi, Ranieri D.; Capetti, Alessandro; Buttiglione, Sara; Chiaberge, Marco; Celotti, Annalisa

    2013-12-01

    We explore the implications of our optical spectroscopic survey of 3CR radio sources with z edge-brightened" (FR II) radio morphology. The sample contains 33 high ionization galaxies (HIGs) and 18 broad line objects (BLOs). According to the UM, HIGs, the narrow line sources, are the nuclearly obscured counterparts of BLOs. The fraction of HIGs indicates a covering factor of the circumnuclear matter of 65% that corresponds, adopting a torus geometry, to an opening angle of 50° ± 5. No dependence on redshift and luminosity on the torus opening angle emerges. We also consider the implications for a "clumpy" torus. The distributions of total radio luminosity of HIGs and BLOs are not statistically distinguishable, as expected from the UM. Conversely, BLOs have a radio core dominance, R, more than ten times larger with respect to HIGs, as expected in case of Doppler boosting when the jets in BLOs are preferentially oriented closer to the line of sight than in HIGs. Modeling the R distributions leads to an estimate of the jet bulk Lorentz factor of Γ ~ 3-5. The test of the UM based on the radio source size is not conclusive due to the limited number of objects and because the size distribution is dominated by the intrinsic scatter rather than by projection effects. The [O II] line luminosities in HIGs and BLOs are similar but the [O III] and [O I] lines are higher in BLOs by a factor of ~2. We ascribe this effect to the presence of a line emitting region located within the walls of the obscuring torus, visible in BLOs but obscured in HIGs, with a density higher than the [O II] critical density. We find evidence that BLOs have broader [O I] and [O III] lines than HIGs of similar [O II] width, as expected in the presence of high density gas in the proximity of the central black hole. In conclusion, the radio and narrow line region (NLR) properties of HIGs and BLOs are consistent with the UM predictions when the partial obscuration of the NLR is taken into account. We

  16. Quasar Absorption Lines and SDSS Galaxies

    Science.gov (United States)

    Shoemaker, Emileigh Suzanne; Scott, Jennifer E.; Oldak, Katarzyna

    2017-01-01

    We present the results of a study of the sightlines of 45 low redshift quasars (0.06 COS that lie within the footprint of the Sloan Digital Sky Survey. We use both the SDSS DR12 galaxy photometric data, including photometric redshifts, and the measured properties of the absorbers along with the known absorption characteristics of the intergalactic medium and the circumgalactic medium of galaxies to assign the most probable galaxy matches for each absorber in the sample, using estimated galaxy luminosities and virial radii as a discriminator. We show that the scheme can recover known galaxy-absorber matches found from spectroscopic data and thus provides a method for identifying likely pairs in photometric data sets as well as targets for spectroscopic follow up.

  17. An HST/COS legacy survey of intervening Si III absorption in the extended gaseous halos of low-redshift galaxies

    Science.gov (United States)

    Richter, P.; Wakker, B. P.; Fechner, C.; Herenz, P.; Tepper-García, T.; Fox, A. J.

    2016-05-01

    Aims: Doubly ionized silicon (Si iii) is a powerful tracer of diffuse ionized gas inside and outside of galaxies. It can be observed in the local Universe in ultraviolet (UV) absorption against bright extragalactic background sources. We here present an extensive study of intervening Si iii-selected absorbers and study the properties of the warm circumgalactic medium (CGM) around low-redshift (z ≤ 0.1) galaxies. Methods: We analyzed the UV absorption spectra of 303 extragalactic background sources, as obtained with the Cosmic Origins Spectrograph (COS) on-board the Hubble Space Telescope (HST). We developed a geometrical model for the absorption-cross section of the CGM around the local galaxy population and compared the observed Si iii absorption statistics with predictions provided by the model. We also compared redshifts and positions of the absorbers with those of ~64 000 galaxies using archival galaxy-survey data to investigate the relation between intervening Si iii absorbers and the CGM. Results: Along a total redshift path of Δz ≈ 24, we identify 69 intervening Si iii systems that all show associated absorption from other low and high ions (e.g., H i, Si ii, Si iv, C ii, C iv). We derive a bias-corrected number density of dN/dz(Si iii)= 2.5 ± 0.4 for absorbers with column densities log N(Si iii) > 12.2, which is ~3 times the number density of strong Mg ii systems at z = 0. This number density matches the expected cross section of a Si iii absorbing CGM around the local galaxy population with a mean covering fraction of ⟨ fc ⟩ = 0.69. For the majority (~60 percent) of the absorbers, we identify possible host galaxies within 300 km s-1 of the absorbers and derive impact parameters ρ files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/590/A68

  18. High velocity blue-shifted FeII absorption in the dwarf star-forming galaxy PHL293B: Evidence for a wind driven supershell?

    CERN Document Server

    Terlevich, R; Bosch, G; Diaz, A I; Hagele, G; Cardaci, M; Firpo, V

    2014-01-01

    X-shooter and ISIS WHT spectra of the starforming galaxy PHL 293B also known as A2228-00 and SDSS J223036.79-000636.9 are presented in this paper. We find broad (FWHM = 1000km/s) and very broad (FWZI = 4000km/s) components in the Balmer lines, narrow absorption components in the Balmer series blueshifted by 800km/s, previously undetected FeII multiplet (42) absorptions also blueshifted by 800km/s, IR CaII triplet stellar absorptions consistent with [Fe/H] < -2.0 and no broad components or blushifted absorptions in the HeI lines. Based on historical records, we found no optical variability at the 5 sigma level of 0.02 mag between 2005 and 2013 and no optical variability at the level of 0.1mag for the past 24 years. The lack of variability rules out transient phenomena like luminous blue variables or SN IIn as the origin of the blue shifted absorptions of HI and FeII. The evidence points to either a young and dense expanding supershell or a stationary cooling wind, in both cases driven by the young cluster w...

  19. Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. III. Detection of Fe II Reverberation in Nine Narrow-Line Seyfert 1 Galaxies

    CERN Document Server

    Hu, Chen; Lu, Kai-Xing; Li, Yan-Rong; Wang, Fang; Qiu, Jie; Bai, Jin-Ming; Kaspi, Shai; Ho, Luis C; Netzer, Hagai; Wang, Jian-Min

    2015-01-01

    This is the third in a series of papers reporting on a large reverberation-mapping campaign aimed to study the properties of active galactic nuclei (AGNs) with high accretion rates. We present new results on the variability of the optical Fe II emission lines in 10 AGNs observed by the Yunnan Observatory 2.4m telescope during 2012--2013. We detect statistically significant time lags, relative to the AGN continuum, in nine of the sources. This accurate measurement is achieved by using a sophisticated spectral fitting scheme that allows for apparent flux variations of the host galaxy, and several narrow lines, due to the changing observing conditions. Six of the newly detected lags are indistinguishable from the Hbeta lags measured in the same sources. Two are significantly longer and one is slightly shorter. Combining with Fe II lags reported in previous studies, we find a Fe II radius--luminosity relationship similar to the one for Hbeta, although our sample by itself shows no clear correlation. The results s...

  20. C IV ABSORBERS ALONG THE SIGHTLINES TO GAMMA-RAY BURSTS

    Directory of Open Access Journals (Sweden)

    N. Tejos

    2009-01-01

    Full Text Available We report on the statistics of strong (Wr > 0:15 A C IV absorbers at z = 1:5 3:5 toward high-redshift Gamma-Ray Bursts (GRBs. In contrast with a recent survey for strong Mg II absorption systems at z < 2, we nd that the number of C IV absorbers per unit redshift dN=dz does not show any signi cant deviation from previous surveys using QSOs as background sources. Although the results for Mg II and C IV absorbers along GRB sightlines appear to contradict one another, we note that the surveys are nearly disjoint: the C IV survey corresponds to higher redshift and more highly ionized gas than the Mg II survey. Nevertheless, analysis on larger statistical samples may constrain properties of the galaxies hosting these metals (e.g. mass, dust content and/or the coherence-length of the gas giving rise to the metal-line absorption.

  1. A galaxy halo with a radius of 65 KPC

    Science.gov (United States)

    Bergeron, J.

    1985-12-01

    In the spectra of QSOs, a large number of absorption lines are observed, and many of these systems are only known on the basis of their absorption characteristics. Special questions arise in connection with the Ly-alpha forest systems. These questions are considered in the context of a discussion of the different types of extrinsic absorption systems. Attention is also given to the detection of a galaxy identified with the absorption system in PKS 2128-12, and the nature of the Mg II absorption system detected in PKS 2128-12. Questions regarding the association of the absorbing cloud on the line of sight to PKS 2128-12 are considered. It is concluded that an association with a very extended disk is more likely than an association with a halo around a spiral galaxy of absolute luminosity Mv = -20.8.

  2. The Hi content of early-type galaxies from the ALFALFA survey. II. The case of low density environments

    Science.gov (United States)

    Grossi, M.; di Serego Alighieri, S.; Giovanardi, C.; Gavazzi, G.; Giovanelli, R.; Haynes, M. P.; Kent, B. R.; Pellegrini, S.; Stierwalt, S.; Trinchieri, G.

    2009-05-01

    Aims: We present the analysis of the Hi content of a sample of early-type galaxies (ETGs) in low-density environments (LDEs) using the data set provided by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We compare their properties to the sample in the Virgo cluster that we studied in a previous paper (di Serego Alighieri et al. 2007, A&A, 474, 851, Paper I). Our aim is both to investigate how the cool interstellar medium (ISM) of these systems depends on the galaxy mass and the environment and to relate the properties of the neutral hydrogen to the warm phases of the ISM. Methods: We have selected a sample of 62 nearby ETGs (V21-cm measurements reported in the literature. One by one comparison with the available material confirms, as expected, that ALFALFA data are, with rare exceptions, of equal or better quality than the best spectra previously obtained for these objects. All together, our analysis doubles the number of known gas-rich ETGs in this area. The Hi detection rate is 44% in luminous ETGs (MB -17). In both cases it is 10 times higher than that of the Virgo cluster. The presence of gas can be related to a recent star formation activity: 60% of all ETGs with Hi have optical emission line ratios typical of star-forming galaxies and blue colours suggesting the presence of young stellar populations, especially in the dwarf subsample. Conclusions: We show that the Hi detection rate of ETGs depends both on the environment and mass. The fraction of early-type systems with neutral hydrogen is higher in more massive objects when compared to early-type dwarfs. The ETGs in LDEs seem to have more heterogeneous properties than their Virgo cluster counterparts, since they are able to retain a cold interstellar gas component and to support star formation activity even at recent epochs.

  3. NIHAO project II: halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations

    Science.gov (United States)

    Butsky, Iryna; Macciò, Andrea V.; Dutton, Aaron A.; Wang, Liang; Obreja, Aura; Stinson, Greg S.; Penzo, Camilla; Kang, Xi; Keller, Ben W.; Wadsley, James

    2016-10-01

    We use the NIHAO (Numerical Investigation of Hundred Astrophysical Objects) cosmological simulations to study the effects of galaxy formation on key properties of dark matter (DM) haloes. NIHAO consists of ≈90 high-resolution smoothed particle hydrodynamics simulations that include (metal-line) cooling, star formation, and feedback from massive stars and supernovae, and cover a wide stellar and halo mass range: 106 ≲ M*/M⊙ ≲ 1011(109.5 ≲ Mhalo/M⊙ ≲ 1012.5). When compared to DM-only simulations, the NIHAO haloes have similar shapes at the virial radius, Rvir, but are substantially rounder inside ≈0.1Rvir. In NIHAO simulations, c/a increases with halo mass and integrated star formation efficiency, reaching ˜0.8 at the Milky Way mass (compared to 0.5 in DM-only), providing a plausible solution to the long-standing conflict between observations and DM-only simulations. The radial profile of the phase-space Q parameter (ρ/σ3) is best fit with a single power law in DM-only simulations, but shows a flattening within ≈0.1Rvir for NIHAO for total masses M > 1011 M⊙. Finally, the global velocity distribution of DM is similar in both DM-only and NIHAO simulations, but in the solar neighbourhood, NIHAO galaxies deviate substantially from Maxwellian. The distribution is more symmetric, roughly Gaussian, with a peak that shifts to higher velocities for Milky Way mass haloes. We provide the distribution parameters which can be used for predictions for direct DM detection experiments. Our results underline the ability of the galaxy formation processes to modify the properties of DM haloes.

  4. Cross-correlation Weak Lensing of SDSS galaxy Clusters II: Cluster Density Profiles and the Mass--Richness Relation

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, David E.; Sheldon, Erin S.; Wechsler, Risa H.; Rozo, Eduardo; Koester, Benjamin P.; Frieman, Joshua A.; McKay, Timothy A.; Evrard, August E.; Becker, Matthew; Annis, James

    2007-09-28

    We interpret and model the statistical weak lensing measurements around 130,000 groups and clusters of galaxies in the Sloan Digital Sky Survey presented by Sheldon et al. (2007). We present non-parametric inversions of the 2D shear profiles to the mean 3D cluster density and mass profiles in bins of both optical richness and cluster i-band luminosity. Since the mean cluster density profile is proportional to the cluster-mass correlation function, the mean profile is spherically symmetric by the assumptions of large-scale homogeneity and isotropy. We correct the inferred 3D profiles for systematic effects, including non-linear shear and the fact that cluster halos are not all precisely centered on their brightest galaxies. We also model the measured cluster shear profile as a sum of contributions from the brightest central galaxy, the cluster dark matter halo, and neighboring halos. We infer the relations between mean cluster virial mass and optical richness and luminosity over two orders of magnitude in cluster mass; the virial mass at fixed richness or luminosity is determined with a precision of {approx} 13% including both statistical and systematic errors. We also constrain the halo concentration parameter and halo bias as a function of cluster mass; both are in good agreement with predictions from N-body simulations of LCDM models. The methods employed here will be applicable to deeper, wide-area optical surveys that aim to constrain the nature of the dark energy, such as the Dark Energy Survey, the Large Synoptic Survey Telescope and space-based surveys.

  5. Spitzer mid-IR spectroscopy of powerful 2Jy and 3CRR radio galaxies. II. AGN power indicators and unification

    Energy Technology Data Exchange (ETDEWEB)

    Dicken, D. [CEA-Saclay, F-91191 Gif-sur-Yvette (France); Tadhunter, C. [University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Morganti, R. [ASTRON, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Axon, D.; Robinson, A.; Magagnoli, M. [Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States); Kharb, P. [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560034 (India); Ramos Almeida, C. [Instituto de Astrofisica de Canarias (IAC), C/V ia Lactea, s/n, E-38205 La Laguna, Tenerife (Spain); Mingo, B. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Hardcastle, M. [School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Nesvadba, N. P. H.; Singh, V. [Institut d' Astrophysique Spatiale, CNRS, Université Paris Sud, F-91405 Orsay (France); Kouwenhoven, M. B. N. [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, Beijing 100871 (China); Rose, M.; Spoon, H. [224 Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Inskip, K. J. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Holt, J., E-mail: daniel.dicken@cea.fr [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

    2014-06-20

    It remains uncertain which continuum and emission line diagnostics best indicate the bolometric powers of active galactic nuclei (AGNs), especially given the attenuation caused by the circumnuclear material and the possible contamination by components related to star formation. Here we use mid-IR spectra along with multiwavelength data to investigate the merit of various diagnostics of AGN radiative power, including the mid-IR [Ne III] λ25.89 μm and [O IV] λ25.89 μm fine-structure lines, the optical [O III] λ5007 forbidden line, and mid-IR 24 μm, 5 GHz radio, and X-ray continuum emission, for complete samples of 46 2Jy radio galaxies (0.05 < z < 0.7) and 17 3CRR FRII radio galaxies (z < 0.1). We find that the mid-IR [O IV] line is the most reliable indicator of AGN power for powerful radio-loud AGNs. By assuming that the [O IV] is emitted isotropically, and comparing the [O III] and 24 μm luminosities of the broad- and narrow-line AGNs in our samples at fixed [O IV] luminosity, we show that the [O III] and 24 μm emission are both mildly attenuated in the narrow-line compared to the broad-line objects by a factor of ≈2. However, despite this attenuation, the [O III] and 24 μm luminosities are better AGN power indicators for our sample than either the 5 GHz radio or the X-ray continuum luminosities. We also detect the mid-IR 9.7 μm silicate feature in the spectra of many objects but not ubiquitously: at least 40% of the sample shows no clear evidence for these features. We conclude that, for the majority of powerful radio galaxies, the mid-IR lines are powered by AGN photoionization.

  6. 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

  7. Mid-infrared properties of luminous infrared galaxies. II. Probing the dust and gas physics of the goals sample

    Energy Technology Data Exchange (ETDEWEB)

    Stierwalt, S.; Armus, L.; Diaz-Santos, T.; Marshall, J.; Haan, S.; Howell, J.; Murphy, E. J.; Inami, H.; Petric, A. O. [Spitzer Science Center, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Charmandaris, V. [Department of Physics, University of Crete, GR-71003 Heraklion (Greece); Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Iwasawa, K. [INAF-Observatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Kim, D. C. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Rich, J. A. [The Observatories, Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Spoon, H. W. W. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); U, V., E-mail: sabrinas@virginia.edu [Department of Physics and Astronomy, University of California, Riverside, CA 92507 (United States)

    2014-08-01

    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 the results of a multi-component, spectral decomposition analysis of the low-resolution mid-infrared (MIR) Spitzer Infrared Spectrograph spectra from 5-38 μm of 244 LIRG nuclei. The detailed fits and high-quality spectra allow for characterization of the individual polycyclic aromatic hydrocarbon (PAH) features, warm molecular hydrogen emission, and optical depths for both silicate dust grains and water ices. We find that starbursting LIRGs, which make up the majority of the GOALS sample, are very consistent in their MIR properties (i.e., τ{sub 9.7μm}, τ{sub ice}, neon line ratios, and PAH feature ratios). However, as their EQW{sub 6.2{sub μm}} decreases, usually an indicator of an increasingly dominant active galactic nucleus (AGN), LIRGs cover a larger spread in these MIR parameters. The contribution from PAH emission to the total IR luminosity (L(PAH)/L(IR)) in LIRGs varies from 2%-29% and LIRGs prior to their first encounter show significantly higher L(PAH)/L(IR) ratios on average. We observe a correlation between the strength of the starburst (represented by IR8 = L{sub IR}/L{sub 8{sub μm}}) and the PAH fraction at 8 μm but no obvious link between IR8 and the 7.7 to 11.3 PAH ratio, suggesting that the fractional photodissociation region (PDR) emission, and not the overall grain properties, is associated with the rise in IR8 for galaxies off the starburst main sequence. We detect crystalline silicate features in ∼6% of the sample but only in the most obscure sources (s{sub 9.7{sub μm}} < –1.24). Ice absorption features are observed in ∼11% (56%) of GOALS LIRGs (ULIRGs) in sources with a range of silicate depths. Most GOALS LIRGs have L(H{sub 2})/L(PAH) ratios elevated above those observed for normal star-forming galaxies and exhibit a trend for increasing L(H{sub 2})/L

  8. The Self-Similarity of the Circumgalactic Medium with Galaxy Virial Mass: Implications for Cold-Mode Accretion

    CERN Document Server

    Churchill, Christopher W; Kacprzak, Glenn G; Trujillo-Gomez, Sebastian

    2013-01-01

    We apply halo abundance matching to obtain galaxy virial masses, M_h, and radii, Rvir, for the 169 isolated galaxies in the "MgII Absorber-Galaxy Catalog" (MAGIICAT, Nielsen et al.). All galaxies have spectroscopic redshifts (0.1 < z < 1.1) and their circumgalactic medium (CGM) is probed in MgII absorption within projected galactocentric distances D < 200 kpc. We examine the behavior of equivalent width, W(2796), and covering fraction, f_c, as a function of D, D/Rvir, and M_h. We find: [1] systematic segregation of M_h on the W(2796)-D plane (4.2 sigma); high-mass halos are found at higher D with larger W(2796) compared to lower mass halos. On the W(2796)-D/Rvir plane, mass segregation vanishes and we find W(2796) ~ (D/Rvir)^-2 (9.5 sigma); [2] higher mass halos have larger f_c at a given D, whereas f_c is independent of M_h at all D/Rvir; [3] f_c is constant with M_h over the range 10.4 < log(M_h/Msun) < 13.3 within a given D or D/Rvir. The combined results suggest that the MgII absorbing CGM ...

  9. Evidence for Expanding Superbubbles in a Galaxy at z=0.7443

    CERN Document Server

    Bond, N A; Charlton, J C; Vogt, S S; Bond, Nicholas A.; Churchill, Chris W.; Charlton, Jane C.

    2001-01-01

    The intervening z=0.7443 Mg II absorption system in the spectrum of MC 1331+170 shows an unusual series of line pairs, each with velocity separations of 30 km/s. These lines could be explained as the shells of expanding superbubbles residing in the outer regions of an edge-on spiral galaxy visible in the optical image of the MC 1331+170 field. The color and brightness of this galaxy make it the most likely candidate z=0.7443 absorber, though two other galaxies in the quasar field could also be contributing to the Mg II absorption profile. Kinematic models of absorption from compact groups and galaxy pairs produce profiles largely inconsistent with the observed Mg II spectrum. Superbubbles would naturally generate more regular structures such as those observed. Photoionization models of the superbubble shell are consistent with the observed profile for many realistic physical conditions. In a pure superbubble model, the large velocity spread of the Mg II absorption system is inconsistent with the expected spre...

  10. Reaching the Peak of the quasar spectral energy distribution - II. Exploring the accretion disc, dusty torus and host galaxy

    CERN Document Server

    Collinson, James S; Landt, Hermine; Done, Chris; Elvis, Martin; McDowell, Jonathan C

    2016-01-01

    We continue our study of the spectral energy distributions (SEDs) of 11 AGN at 1.5 < z < 2.2, with optical-NIR spectra, X-ray data and mid-IR photometry. In a previous paper we presented the observations and models; in this paper we explore the parameter space of these models. We first quantify uncertainties on the black hole masses (M$_{\\rm BH}$) and degeneracies between SED parameters. The effect of BH spin is tested, and we find that while low to moderate spin values (a$_*$ $\\leq$ 0.9) are compatible with the data in all cases, maximal spin (a$_*$ = 0.998) can only describe the data if the accretion disc is face-on. The outer accretion disc radii are well constrained in 8/11 objects, and are found to be a factor ~5 smaller than the self-gravity radii. We then extend our modelling campaign into the mid-IR regime with WISE photometry, adding components for the host galaxy and dusty torus. Our estimates of the host galaxy luminosities are consistent with the M$_{\\rm BH}$-bulge relationship, and the meas...

  11. Stellar Orbital Studies in Normal Spiral Galaxies II: Restrictions to Structural and Dynamical parameters on Spiral Arms

    CERN Document Server

    Pérez-Villegas, Angeles; Moreno, Edmundo

    2015-01-01

    Making use of a set of detailed potential models for normal spiral galaxies, we analyze the disk stellar orbital dynamics as the structural and dynamical parameters of the spiral arms (mass, pattern speed and pitch angle) are gradually modified. With this comprehensive study of ordered and chaotic behavior, we constructed an assemblage of orbitally supported galactic models and plausible parameters for orbitally self-consistent spiral arms models. We find that, to maintain orbital support for the spiral arms, the spiral arm mass, M$_{sp}$, must decrease with the increase of the pitch angle, $i$; if $i$ is smaller than $\\sim10\\deg$, M$_{sp}$ can be as large as $\\sim7\\%$, $\\sim6\\%$, $\\sim5\\%$ of the disk mass, for Sa, Sb, and Sc galaxies, respectively. If $i$ increases up to $\\sim25\\deg$, the maximum M$_{sp}$ is $\\sim1\\%$ of the disk mass independently in this case of morphological type. For values larger than these limits, spiral arms would likely act as transient features. Regarding the limits posed by extrem...

  12. Reaching the peak of the quasar spectral energy distribution - II. Exploring the accretion disc, dusty torus and host galaxy

    Science.gov (United States)

    Collinson, James S.; Ward, Martin J.; Landt, Hermine; Done, Chris; Elvis, Martin; McDowell, Jonathan C.

    2017-02-01

    We continue our study of the spectral energy distributions (SEDs) of 11 active galactic nuclei (AGN) at 1.5 maximal spin (a* = 0.998) can only describe the data if the accretion disc is face-on. The outer accretion disc radii are well constrained in 8/11 objects and are found to be a factor ˜5 smaller than the self-gravity radii. We then extend our modelling campaign into the mid-IR regime with Wide-field Infrared Survey Explorer photometry, adding components for the host galaxy and dusty torus. Our estimates of the host galaxy luminosities are consistent with the MBH-bulge relationship, and the measured torus properties (covering factor and temperature) are in agreement with earlier work, suggesting a predominantly silicate-based grain composition. Finally, we deconvolve the optical-NIR spectra using our SED continuum model. We claim that this is a more physically motivated approach than using empirical descriptions of the continuum such as broken power laws. For our small sample, we verify previously noted correlations between emission linewidths and luminosities commonly used for single-epoch MBH estimates, and observe a statistically significant anticorrelation between [O III] equivalent width and AGN luminosity.

  13. Search for Extremely Metal-poor Galaxies in the Sloan Digital Sky Survey (II): high electron temperature objects

    CERN Document Server

    Almeida, J Sanchez; Morales-Luis, A B; Munoz-Tunon, C; Garcia-Benito, R; Nuza, S E; Kitaura, F S

    2016-01-01

    Extremely metal-poor (XMP) galaxies are defined to have gas-phase metallicity smaller than a tenth of the solar value (12 + log[O/H] < 7.69). They are uncommon, chemically and possibly dynamically primitive, with physical conditions characteristic of earlier phases of the Universe. We search for new XMPs in the Sloan Digital Sky Survey (SDSS) in a work that complements Paper I. This time high electron temperature objects are selected; since metals are a main coolant of the gas, metal- poor objects contain high-temperature gas. Using the algorithm k-means, we classify 788677 spectra to select 1281 galaxies having particularly intense [OIII]4363 with respect to [OIII]5007, which is a proxy for high electron temperature. The metallicity of these candidates was computed using a hybrid technique consistent with the direct method, rendering 196 XMPs. A less restrictive noise constraint provides a larger set with 332 candidates. Both lists are provided in electronic format. The selected XMP sample have mean stell...

  14. The interstellar medium and star formation in edge-on galaxies. II. NGC 4157, 4565, and 5907

    Energy Technology Data Exchange (ETDEWEB)

    Yim, Kijeong; Wong, Tony; Xue, Rui [Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801 (United States); Rand, Richard J. [Department of Physics and Astronomy, University of New Mexico, 1919 Lomas Boulevard NE, Albuquerque, NM 87131-1156 (United States); Rosolowsky, Erik [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB T6G 2E1 (Canada); Hulst, J. M. van der [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands); Benjamin, Robert [Department of Physics, University of Wisconsin-Whitewater, 800 West Main Street, Whitewater, WI 53190 (United States); Murphy, Eric J., E-mail: k.yim@astro.rug.nl [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2014-12-01

    We present a study of the vertical structure of the gaseous and stellar disks in a sample of edge-on galaxies (NGC 4157, 4565, and 5907) using BIMA/CARMA {sup 12}COJ=1→0, VLA Hi, and Spitzer 3.6 μm data. In order to take into account projection effects when we measure the disk thickness as a function of radius, we first obtain the inclination by modeling the radio data. Using the measurement of the disk thicknesses and the derived radial profiles of gas and stars, we estimate the corresponding volume densities and vertical velocity dispersions. Both stellar and gas disks have smoothly varying scale heights and velocity dispersions, contrary to assumptions of previous studies. Using the velocity dispersions, we find that the gravitational instability parameter Q follows a fairly uniform profile with radius and is ⩾1 across the star-forming disk. The star formation law has a slope that is significantly different from those found in more face-on galaxy studies, both in deprojected and pixel-by-pixel plots. Midplane gas pressure based on the varying scale heights and velocity dispersions appears to roughly hold a power-law correlation with the midplane volume density ratio.

  15. NIBLES - an HI census of stellar mass selected SDSS galaxies: II. Arecibo follow-up HI observations

    CERN Document Server

    Butcher, Z; van Driel, W; Lehnert, M D; Minchin, R

    2016-01-01

    We obtained Arecibo HI line follow-up observations of 154 of the 2600 galaxies in the Nan\\c{c}ay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) sample. These observations are on average four times more sensitive than the original observations at the Nan\\c{c}ay Radio Telescope. The main goal of this survey is to characterize the underlying HI properties of the NIBLES galaxies which were undetected or marginally detected at Nan\\c{c}ay. Of the Nan\\c{c}ay non-detections, 85% were either clearly or marginally detected at Arecibo, while 89% of the Nan\\c{c}ay marginal detections were clearly detected. Based on the statistics of the detections relative to g-i color and r-band luminosity (L$_r$) distribution among our Arecibo observations, we anticipate ~60% of our 867 Nan\\c{c}ay non-detections and marginal detections could be detected at the sensitivity of our Arecibo observations. Follow-up observations of our low luminosity (L$_r$ < 10$^{8.5}$ L$_{\\odot}$) blue sources indicate that they have, on aver...

  16. 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...

  17. Galaxy Clusters in the Swift/BAT era II: 10 more Clusters detected above 15 keV

    Energy Technology Data Exchange (ETDEWEB)

    Ajello, M.; /SLAC /KIPAC, Menlo Park; Rebusco, P.; /KIPAC, Menlo Park; Cappelluti, N.; /Garching, Max Planck Inst., MPE /Maryland U., Baltimore County; Reimer, O.; /SLAC /Palermo Observ.; Boehringer, H.; /Garching, Max Planck Inst., MPE; La Parola, V.; Cusumano, G.; /Palermo Observ.

    2010-10-27

    We report on the discovery of 10 additional galaxy clusters detected in the ongoing Swift/BAT all-sky survey. Among the newly BAT-discovered clusters there are: Bullet, Abell 85, Norma, and PKS 0745-19. Norma is the only cluster, among those presented here, which is resolved by BAT. For all the clusters we perform a detailed spectral analysis using XMM-Newton and Swift/BAT data to investigate the presence of a hard (non-thermal) X-ray excess. We find that in most cases the clusters emission in the 0.3-200 keV band can be explained by a multi-temperature thermal model confirming our previous results. For two clusters (Bullet and Abell 3667) we find evidence for the presence of a hard X-ray excess. In the case of the Bullet cluster, our analysis confirms the presence of a non-thermal, power-law like, component with a 20-100 keV flux of 3.4 x 10{sup -12} erg cm{sup -2} s{sup -1} as detected in previous studies. For Abell 3667 the excess emission can be successfully modeled as a hot component (kT = {approx}13 keV). We thus conclude that the hard X-ray emission from galaxy clusters (except the Bullet) has most likely thermal origin.

  18. The Arecibo Galaxy Environment Survey: II. A HI view of the Abell cluster 1367 and its outskirts

    CERN Document Server

    Cortese, L; Auld, R R; Davies, J I; Catinella, B; Momjian, E; Rosenberg, J L; Taylor, R; Gavazzi, G; O'Neil, K; Baes, M; Boselli, A; Bothun, G; Koribalski, B; Schneider, S; Van Driel, W

    2007-01-01

    We present 21 cm HI line observations of 5x1 square degrees centered on the local Abell cluster 1367 obtained as part of the Arecibo Galaxy Environment Survey. One hundred sources are detected (79 new HI measurements and 50 new redshifts), more than half belonging to the cluster core and its infalling region. Combining the HI data with SDSS optical imaging we show that our HI selected sample follows scaling relations similar to the ones usually observed in optically selected samples. Interestingly all galaxies in our sample appear to have nearly the same baryon fraction independently of their size, surface brightness and luminosity. The most striking difference between HI and optically selected samples resides in their large scale distribution: whereas optical and X-ray observations trace the cluster core very well, in HI there is almost no evidence of the presence of the cluster. Some implications on the determination of the cluster luminosity function and HI distribution for samples selected at different wa...

  19. 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