WorldWideScience

Sample records for 70micron-selected galaxies starburst

  1. Starburst Galaxies

    Muxlow, T W B; Richards, A M S; Thrall, H

    2006-01-01

    Star-formation and the Starburst phenomenon are presented with respect to a number of nearby star-forming galaxies where our understanding of the process can be calibrated. Methods of estimating star-formation rates are discussed together with the role played in the investigation of the process by multi-wavelength studies of a few selected starburst galaxies (especially the well studied galaxy M82). Our understanding of nearby systems allows us to study the star-formation history of the Universe by observing high-redshift starburst galaxies. These begin to dominate the radio source populations at centimetric wavelengths at flux densities below a few 10s of Jy. New very sensitive, high resolution telescopes in the sub-mm and radio will revolutionize our understanding of these distant star-forming systems, some of which may contain embedded AGN.

  2. The PDS starburst galaxies

    Coziol, R; Quast, G; Contini, T; Davoust, E

    1998-01-01

    (Abridged) We discuss the nature of the galaxies found in the Pico dos Dias Survey (PDS) for young stellar objects. The PDS galaxies were selected from the IRAS Point Source catalog. They have flux density of moderate or high quality at 12, 25 and 60 $\\mu$m and spectral indices in the ranges $-3.00 \\leq criteria allowed the detection of 382 galaxies, which are a mixture of starburst and Seyfert galaxies. The starburst galaxies show an excess of FIR luminosity and their IRAS colors are significantly different from those of Seyfert galaxies -- 99% of the starburst galaxies in our sample have a spectral index $\\alpha(60,25) -2.5$. This color cut--off also marks a change in the dominant morphologies of the galaxies: the normal IRAS galaxies are preferentially late--type spirals (Sb and later), while the starbursts are more numerous among early--type spirals (earlier than Sbc). No difference is found between the starbursts detected in the FIR and those detected on the basis of UV excess. The PDS starburst galaxie...

  3. Formaldehyde Densitometry of Starburst Galaxies

    Mangum, Jeffrey G; Menten, Karl M; Henkel, Christian

    2007-01-01

    With a goal toward deriving the physical conditions in external galaxies, we present a survey of the formaldehyde emission in a sample of starburst systems. By extending a technique used to derive the spatial density in star formation regions in our own Galaxy, we show how the relative intensity of the 1(10)-1(11) and 2(11)-2(12) K-doublet transitions of H2CO can provide an accurate densitometer for the active star formation environments found in starburst galaxies. Relying upon an assumed kinetic temperature and co-spatial emission and absorption from both H2CO transitions, our technique is applied to a sample of nineteen IR-bright galaxies which exhibit various forms of starburst activity. In the five galaxies of our sample where both H2CO transitions were detected we have derived spatial densities. We also use H2CO to estimate the dense gas mass in our starburst galaxy sample, finding similar mass estimates for the dense gas forming stars in these objects as derived using other dense gas tracers. A related...

  4. ISO Images of Starbursts and Active Galaxies

    Mirabel, I F

    1999-01-01

    We present some highlights from the mid-infrared (5-16 micron) images of mergers of massive galaxies obtained with the Infrared Space Observatory (ISO). We have observed: 1) ultraluminous infrared nuclei, 2) luminous dust-enshrouded extranuclear starbursts, and 3) active galaxy nuclei (AGNs). In this contribution we discuss the observations of Arp 299, a prototype for very luminous infrared galaxies, the Antennae which is a prototype of mergers, and Centaurus A which is the closest AGN to Earth. From these observations we conclude the following: 1) the most intense starbursts in colliding systems of galaxies and the most massive stars are dust-enshrouded in regions that appear inconspicuous at optical wavelengths, 2) the most intense nuclear infrared sources are a combination of AGN and starburst activity, 3) the hosts of radio loud AGNs that trigger giant double-lobe structures may be symbiotic galaxies composed of barred spirals inside ellipticals.

  5. Densitometry and Thermometry of Starburst Galaxies

    Mangum, Jeffrey G; Menten, Karl M; Henkel, Christian; MacGregor, Meredith

    2011-01-01

    With a goal toward deriving the physical conditions in external galaxies, we present a survey of formaldehyde (H2CO) and ammonia (NH3) emission and absorption in a sample of starburst galaxies using the Green Bank Telescope. By extending well-established techniques used to derive the spatial density in star formation regions in our own Galaxy, we show how the relative intensity of the 1(10)-1(11) and 2(11)-2(12) K-doublet transitions of H2CO can provide an accurate densitometer for the active star formation environments found in starburst galaxies (c.f. Mangum et al. 2008). Similarly, we employ the well-established technique of using the relative intensities of the (1,1), (2,2), and (4,4) transitions of NH3 to derive the kinetic temperature in starburst galaxies. Our measurements of the kinetic temperature constrained spatial density in our starburst galaxy sample represent the first mean density measurements made toward starburst galaxies. We note a disparity between kinetic temperature measurements derived ...

  6. The Nature of Starbursts : II. The Duration of Starbursts in Dwarf Galaxies

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

    2010-01-01

    The starburst phenomenon can shape the evolution of the host galaxy and the surrounding intergalactic medium. The extent of the evolutionary impact is partly determined by the duration of the starburst, which has a direct correlation with both the amount of stellar feedback and the development of galactic winds, particularly for smaller mass dwarf systems. We measure the duration of starbursts in twenty nearby, ongoing, and "fossil" starbursts in dwarf galaxies based on the recent star format...

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

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

    2010-01-01

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

  8. The True Durations of Starbursts: HST Observations of Three Nearby Dwarf Starburst Galaxies

    McQuinn, Kristen B W; Cannon, John M; Dalcanton, Julianne J; Dolphin, Andrew; Stark, David; Weisz, Daniel

    2009-01-01

    The duration of a starburst is a fundamental parameter affecting the evolution of galaxies yet, to date, observational constraints on the durations of starbursts are not well established. Here we study the recent star formation histories (SFHs) of three nearby dwarf galaxies to rigorously quantify the duration of their starburst events using a uniform and consistent approach. We find that the bursts range from ~200 - ~400 Myr in duration resolving the tension between the shorter timescales often derived observationally with the longer timescales derived from dynamical arguments. If these three starbursts are typical of starbursts in dwarf galaxies, then the short timescales (3 - 10 Myr) associated with starbursts in previous studies are best understood as "flickering" events which are simply small components of the larger starburst. In this sample of three nearby dwarfs, the bursts are not localized events. All three systems show bursting levels of star formation in regions of both high and low stellar densit...

  9. The True Durations of Starbursts: HST Observations of Three Nearby Dwarf Starburst Galaxies

    McQuinn, Kristen B W; Skillman, Evan D.; Cannon, John M.; Dalcanton, Julianne J.; Dolphin, Andrew; Stark, David; Weisz, Daniel

    2009-01-01

    The duration of a starburst is a fundamental parameter affecting the evolution of galaxies yet, to date, observational constraints on the durations of starbursts are not well established. Here we study the recent star formation histories (SFHs) of three nearby dwarf galaxies to rigorously quantify the duration of their starburst events using a uniform and consistent approach. We find that the bursts range from ~200 - ~400 Myr in duration resolving the tension between the shorter timescales of...

  10. Post-Starburst Quasars: Bridging the Gap Between Post-Starburst Galaxies and Quasars

    Cales, Sabrina L

    2015-01-01

    In order to better understand the nature of post-starburst quasars (PSQs) in the context of galaxy evolution, we compare their properties to those of post-starburst galaxies and quasars from appropriately selected samples possessing similar redshift ($z \\sim 0.3$), luminosity ($M_r \\sim -$23), and data quality. We consider morphologies, spectral features, and derived physical properties of the stellar populations and central supermassive black hole. PSQs themselves come in two types: the more luminous AGNs with more luminous post-starburst stellar populations hosted by elliptical galaxies, some which are clearly merger products, and the less luminous systems existing within relatively undisturbed spiral galaxies and possessing signs of a more extended period of star formation. Post-starburst galaxies (PSQs) have elliptical and disturbed/post-merger morphologies similar to those of the more luminous PSQs, display similar spectral properties, but also can have younger stellar populations for a given starburst m...

  11. The Chemical Evolution of Starburst Nucleus Galaxies

    Coziol, R; Davoust, E; Considère, S

    1997-01-01

    The metallicities derived from spectroscopic observations of a sample of Starburst Nucleus Galaxies (SBNGs) are compared to those of several other types of galaxies (normal giant galaxies, Irregular and HII galaxies) drawn from the literature. The SBNGs are deficient in metals with respect to normal galaxies of same morphological type, suggesting that - SBNGs are galaxies still in the process of formation. Breaking the SBNGs into early-types (Sb and earlier) and late-types reveals that the former seem to follow the same linear luminosity-metallicity relation as the irregular and elliptical galaxies, whereas the latter and the giant spirals show comparable (0.2 and 0.3 dex) excess abundances with respect to the linear relation. This difference between the two types of SBNGs is consistent with the predictions of the model of hierarchical formation of galaxies: the early-type SBNGs are building their bulges by successive mergers of small stellar and gaseous systems, while the late-type SBNGs are mostly accreting...

  12. From Starburst to Quiescence: Testing AGN feedback in Rapidly Quenching Post-Starburst Galaxies

    Yesuf, Hassen M; Trump, Jonathan R; Koo, David C; Fang, Jerome J; Liu, F S; Wild, Vivienne; Hayward, Christopher C

    2014-01-01

    Post-starbursts are galaxies in transition from the blue cloud to the red sequence. Although they are rare today, integrated over time they may be an important pathway to the red sequence. This work uses SDSS, GALEX, and WISE observations to identify the evolutionary sequence from starbursts to fully quenched post-starbursts in the narrow mass range $\\log M(M_\\odot) = 10.3-10.7$, and identifies "transiting" post-starbursts which are intermediate between these two populations. In this mass range, $\\sim 0.3\\%$ of galaxies are starbursts, $\\sim 0.1\\%$ are quenched post-starbursts, and $\\sim 0.5\\%$ are the transiting types in between. The transiting post-starbursts have stellar properties that are predicted for fast-quenching starbursts and morphological characteristics that are already typical of early-type galaxies. The AGN fraction, as estimated from optical line ratios, of these post-starbursts is about 3 times higher ($\\gtrsim 36 \\pm 8 \\%$) than that of normal star-forming galaxies of the same mass, but ther...

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

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

  14. From starburst to quiescence: testing active galactic nucleus feedback in rapidly quenching post-starburst galaxies

    Yesuf, Hassen M.; Faber, S. M.; Trump, Jonathan R.; Koo, David C.; Fang, Jerome J.; Liu, F. S. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Wild, Vivienne [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS (United Kingdom); Hayward, Christopher C. [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany)

    2014-09-10

    Post-starbursts are galaxies in transition from the blue cloud to the red sequence. Although they are rare today, integrated over time they may be an important pathway to the red sequence. This work uses Sloan Digital Sky Survey, the Galaxy Evolution Explorer, and Wide-field Infrared Survey Explorer observations to identify the evolutionary sequence from starbursts to fully quenched post-starbursts (QPSBs) in the narrow mass range log M(M {sub ☉}) = 10.3-10.7, and identifies 'transiting' post-starbursts (TPSBs) which are intermediate between these two populations. In this mass range, ∼0.3% of galaxies are starbursts, ∼0.1% are QPSBs, and ∼0.5% are the transiting types in between. The TPSBs have stellar properties that are predicted for fast-quenching starbursts and morphological characteristics that are already typical of early-type galaxies. The active galactic nucleus (AGN) fraction, as estimated from optical line ratios, of these post-starbursts is about three times higher (≳ 36% ± 8%) than that of normal star forming galaxies of the same mass, but there is a significant delay between the starburst phase and the peak of nuclear optical AGN activity (median age difference of ≳ 200 ± 100 Myr), in agreement with previous studies. The time delay is inferred by comparing the broadband near-NUV-to-optical photometry with stellar population synthesis models. We also find that starbursts and post-starbursts are significantly more dust obscured than normal star forming galaxies in the same mass range. About 20% of the starbursts and 15% of the TPSBs can be classified as 'dust-obscured galaxies' (DOGs), with a near-UV-to-mid-IR flux ratio of ≳ 900, while only 0.8% of normal galaxies are DOGs. The time delay between the starburst phase and AGN activity suggests that AGNs do not play a primary role in the original quenching of starbursts but may be responsible for quenching later low-level star formation by removing gas and dust during

  15. From Starburst to Quiescence: Testing Active Galactic Nucleus feedback in Rapidly Quenching Post-starburst Galaxies

    Yesuf, Hassen M.; Faber, S. M.; Trump, Jonathan R.; Koo, David C.; Fang, Jerome J.; Liu, F. S.; Wild, Vivienne; Hayward, Christopher C.

    2014-09-01

    Post-starbursts are galaxies in transition from the blue cloud to the red sequence. Although they are rare today, integrated over time they may be an important pathway to the red sequence. This work uses Sloan Digital Sky Survey, the Galaxy Evolution Explorer, and Wide-field Infrared Survey Explorer observations to identify the evolutionary sequence from starbursts to fully quenched post-starbursts (QPSBs) in the narrow mass range log M(M ⊙) = 10.3-10.7, and identifies "transiting" post-starbursts (TPSBs) which are intermediate between these two populations. In this mass range, ~0.3% of galaxies are starbursts, ~0.1% are QPSBs, and ~0.5% are the transiting types in between. The TPSBs have stellar properties that are predicted for fast-quenching starbursts and morphological characteristics that are already typical of early-type galaxies. The active galactic nucleus (AGN) fraction, as estimated from optical line ratios, of these post-starbursts is about three times higher (gsim 36% ± 8%) than that of normal star forming galaxies of the same mass, but there is a significant delay between the starburst phase and the peak of nuclear optical AGN activity (median age difference of >~ 200 ± 100 Myr), in agreement with previous studies. The time delay is inferred by comparing the broadband near-NUV-to-optical photometry with stellar population synthesis models. We also find that starbursts and post-starbursts are significantly more dust obscured than normal star forming galaxies in the same mass range. About 20% of the starbursts and 15% of the TPSBs can be classified as "dust-obscured galaxies" (DOGs), with a near-UV-to-mid-IR flux ratio of >~ 900, while only 0.8% of normal galaxies are DOGs. The time delay between the starburst phase and AGN activity suggests that AGNs do not play a primary role in the original quenching of starbursts but may be responsible for quenching later low-level star formation by removing gas and dust during the post-starburst phase.

  16. THE NATURE OF STARBURSTS. I. THE STAR FORMATION HISTORIES OF EIGHTEEN NEARBY STARBURST DWARF GALAXIES

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

  17. Densitometry and Thermometry of Starburst Galaxies

    Mangum, J. G.; Darling, J.; Menten, K. M.; Henkel, C.; Aalto, S.; Spaans, M.; van der Werf, P.; Ginsburg, A.; Fomalont, E.; Cotton, B.; Kent, B.

    2016-05-01

    With a goal toward deriving the physical conditions in external galaxies, we have conducted a survey and subsequent high spatial resolution imaging of formaldehyde (H2CO) and ammonia (NH3) emission and absorption in a sample of starburst galaxies. In this article we present the results from a subset of this survey which focuses on high spatial resolution measurements of volume density- and kinetic temperature-sensitive transitions of the H2CO molecule. The volume density structure toward the nuclear region of NGC 253 has been derived from θ ≃ 4 arcsec NRAO Very Large Array (VLA) measurements of the 110 - 111 and 211 - 212 K-doublet transitions of H2CO. The kinetic temperature structure toward NGC 253 and NGC 4945 has been derived from θ ≃ 0.5 - 1.0 arcsec measurements of the H2CO 3K-1K+1 - 2K-1K+1 (near 218 GHz) and 5K-1K+1 - 4K-1K+1 (near 365 GHz) transitions acquired using the Atacama Large Millimeter/submillimeter Array (ALMA). These measurements have allowed us to characterize the dense gas and kinetic temperature structure within these star forming galaxies, which is a first step toward associating dense star-forming gas and the heating processes at work within galaxies.

  18. Long-slit spectroscopy of starburst galaxies

    Long-slit spectroscopy of nine optically luminous starburst galaxies (SBGs) is presented that shows that star formation is not confined to their nuclei, but extends up to kpc from their centers. This extended emission, coupled with their narrow line widths and low ionization, morphologically and spectroscopically distinguish SBGs from AGN. The rotation curves and velocity profiles both suggest that the star formation occurs in a large, disk-shaped volume which is supported by rotation and contains from tens to thousands of separate, massive H II region complexes. Given the large spatial extent of the star formation and its disk environment, it is difficult to see how an evolutionary link between SBGs and AGN could operate. 29 references

  19. Long-slit spectroscopy of starburst galaxies

    De Robertis, M.M.; Shaw, R.A.

    1988-06-01

    Long-slit spectroscopy of nine optically luminous starburst galaxies (SBGs) is presented that shows that star formation is not confined to their nuclei, but extends up to kpc from their centers. This extended emission, coupled with their narrow line widths and low ionization, morphologically and spectroscopically distinguish SBGs from AGN. The rotation curves and velocity profiles both suggest that the star formation occurs in a large, disk-shaped volume which is supported by rotation and contains from tens to thousands of separate, massive H II region complexes. Given the large spatial extent of the star formation and its disk environment, it is difficult to see how an evolutionary link between SBGs and AGN could operate. 29 references.

  20. FISICA observations of the starburst galaxy, NGC 1569

    Clark, D. M.; Eikenberry, S. S.; Raines, S. N.; Gruel, N.; Elston, R.; Guzman, R.; Julian, J.; Boreman, G.; Glenn, P. E.; Hull-Allen, C. G.; Hoffman, J.; Rodgers, M.; Thompson, K.; Flint, S.; Comstock, L.; Myrick, B.

    2006-06-01

    Using the Florida Image Slicer for Infrared Cosmology and Astrophysics (FISICA) we obtained observations of the dwarf starburst galaxy NGC 1569. We present our JH band spectra, particularly noting the existence of extended emission in Paschen β and He I.

  1. THE NATURE OF STARBURSTS. II. THE DURATION OF STARBURSTS IN DWARF GALAXIES

    The starburst phenomenon can shape the evolution of the host galaxy and the surrounding intergalactic medium. The extent of the evolutionary impact is partly determined by the duration of the starburst, which has a direct correlation with both the amount of stellar feedback and the development of galactic winds, particularly for smaller mass dwarf systems. We measure the duration of starbursts in twenty nearby, ongoing, and 'fossil' starbursts in dwarf galaxies based on the recent star formation histories derived from resolved stellar population data obtained with the Hubble Space Telescope. Contrary to the shorter times of 3-10 Myr often cited, the starburst durations we measure range from 450to650 Myr in fifteen of the dwarf galaxies and up to 1.3 Gyr in four galaxies; these longer durations are comparable to or longer than the dynamical timescales for each system. The same feedback from massive stars that may quench the flickering star formation does not disrupt the overall burst event in our sample of galaxies. While five galaxies present fossil bursts, fifteen galaxies show ongoing bursts and thus the final durations may be longer than we report here for these systems. One galaxy shows a burst that has been ongoing for only 20 Myr; we are likely seeing the beginning of a burst event in this system. Using the duration of the starbursts, we calculate that the bursts deposited 1053.9-1057.2 erg of energy into the interstellar medium through stellar winds and supernovae, and produced 3%-26% of the host galaxy's mass.

  2. The Nature of Starbursts : II. The Duration of Starbursts in Dwarf Galaxies

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

    2010-01-01

    The starburst phenomenon can shape the evolution of the host galaxy and the surrounding intergalactic medium. The extent of the evolutionary impact is partly determined by the duration of the starburst, which has a direct correlation with both the amount of stellar feedback and the development of galactic winds, particularly for smaller mass dwarf systems. We measure the duration of starbursts in twenty nearby, ongoing, and "fossil" starbursts in dwarf galaxies based on the recent star formation histories derived from resolved stellar population data obtained with the Hubble Space Telescope. Contrary to the shorter times of 3-10 Myr often cited, the starburst durations we measure range from 450 - 650 Myr in fifteen of the dwarf galaxies and up to 1.3 Gyr in four galaxies; these longer durations are comparable to or longer than the dynamical timescales for each system. The same feedback from massive stars that may quench the flickering SF does not disrupt the overall burst event in our sample of galaxies. Whil...

  3. Post-starburst galaxies: more than just an interesting curiosity

    Wild, Vivienne; Johansson, Peter H; Tresse, Laurence; Charlot, Stephane; Pollo, Agnieszka; Le Fevre, Olivier; de Ravel, Loic

    2008-01-01

    From the VIMOS VLT DEEP Survey (VVDS) we select a sample of 16 galaxies with spectra which identify them as having recently undergone a strong starburst and subsequent fast quenching of star formation. These post-starburst galaxies lie in the redshift range 0.510^9.75Msun. They have a number density of 1x10^-4 per Mpc^3, almost two orders of magnitude sparser than the full galaxy population with the same mass limit. We compare with simulations to show that the galaxies are consistent with being the descendants of gas rich major mergers. Starburst mass fractions must be larger than ~5-10% and decay times shorter than ~10^8 years for post-starburst spectral signatures to be observed in the simulations. We find that the presence of black hole feedback does not greatly affect the evolution of the simulated merger remnants through the post-starburst phase. The multiwavelength spectral energy distributions of the post-starburst galaxies show that 5/16 have completely ceased the formation of new stars. These 5 galax...

  4. Starburst Galaxies: Outflows of Metals and Energy into the IGM

    Strickland, David K; Ptak, Andrew; Schlegel, Eric; Tremonti, Christy; Tsuru, Takeshi; Tuellmann, Ralph; Zezas, Andreas

    2009-01-01

    What is the contribution of mass, metals and energy from starburst galaxies to the Intergalactic Medium? Starburst galaxies drive galactic-scale outflows or "superwinds" that may be responsible for removing metals from galaxies and polluting the Intergalactic Medium (IGM). In the last decade tremendous progress was made in mapping cool entrained gas in superwinds through UV/optical imaging and absorption line spectroscopy. These studies demonstrated that superwinds are ubiquitous in galaxies forming stars at high surface densities and that the most powerful starbursts can drive outflows near escape velocity. Theoretical models of galaxy evolution have begun to incorporate superwinds, using various ad-hoc prescriptions based on our knowledge of the cool gas. However, these efforts are fundamentally impeded by our lack of information about the hot phase of these outflows. The hot X-ray emitting phase of a superwind contains the majority of its energy and newly-synthesized metals, and given its high specific ene...

  5. Radio Observations of Super Star Clusters in Dwarf Starburst Galaxies

    Stevens, I R; Norris, R P; Stevens, Ian R.; Forbes, Duncan A.; Norris, Ray P.

    2002-01-01

    We present new radio continuum observations of two dwarf starburst galaxies, NGC3125 and NGC5408, with observations at 4.80GHz (6cm) and 8.64GHz (3cm), taken with the Australia Telescope Compact Array (ATCA). Both galaxies show a complex radio morphology with several emission regions, mostly coincident with massive young star clusters. The radio spectral indices of these regions are negative (with alpha ~ -0.5 - -0.7), indicating that the radio emission is dominated by synchrotron emission associated with supernova activity from the starburst. One emission region in NGC5408 has a flatter index (alpha ~ -0.1) indicative of optically thin free-free emission, which could indicate it is a younger cluster. Consequently, in these galaxies we do not see regions with the characteristic positive spectral index indicative of optically obscured star-formation regions, as seen in other dwarf starbursts such as Hen 2-10.

  6. The link between mass distribution and starbursts in dwarf galaxies

    McQuinn, Kristen B W; Skillman, Evan D; Dolphin, Andrew E; McGaugh, Stacy S; Williams, Benjamin F

    2015-01-01

    Recent studies have shown that starburst dwarf galaxies have steeply rising rotation curves in their inner parts, pointing to a close link between the intense star formation and a centrally concentrated mass distribution (baryons and dark matter). More quiescent dwarf irregulars typically have slowly rising rotation curves, although some "compact" irregulars with steep, inner rotation curves exist. We analyze archival Hubble Space Telescope images of two nearby "compact" irregular galaxies (NGC 4190 and NGC 5204), which were selected solely on the basis of their dynamical properties and their proximity. We derive their recent star-formation histories by fitting color-magnitude diagrams of resolved stellar populations, and find that the star-formation properties of both galaxies are consistent with those of known starburst dwarfs. Despite the small sample, this strongly reinforces the notion that the starburst activity is closely related to the inner shape of the potential well.

  7. Starburst Intensity Limit of Galaxies at z~5-6

    Hathi, N P; Rhoads, J E

    2007-01-01

    The peak star formation intensity in starburst galaxies does not vary significantly from the local universe to redshift z~6. We arrive at this conclusion through new surface brightness measurements of 47 starburst galaxies at z~5-6, doubling the redshift range for such observations. These galaxies are spectroscopically confirmed in the Hubble Ultra Deep Field (HUDF) through the GRism ACS program for Extragalactic Science (GRAPES) project. The starburst intensity limit for galaxies at z~5-6 agree with those at z~3-4 and z~0 to within a factor of a few, after correcting for cosmological surface brightness dimming and for dust. The most natural interpretation of this constancy over cosmic time is that the same physical mechanisms limit starburst intensity at all redshifts up to z~6 (be they galactic winds, gravitational instability, or something else). We do see two trends with redshift: First, the UV spectral slope of galaxies at z~5-6 is bluer than that of z~3 galaxies, suggesting an increase in dust content o...

  8. Multi-Wavelength Observations of Nearby Starburst Galaxies

    Lee, Janice

    2015-08-01

    Do cycles of violent, intense, but short-lived bursts constitute a significant mode of global star formation in present-day galaxies? Such events can have a profound effect on galaxies, particularly those with shallow potential wells, and observational measures of their prevalence inform our understanding of a wide range of issues in galaxy evolution. I will highlight what we have learned about starbursts from multi-wavelength observations of galaxies in the local volume on both galactic and smaller scales, and explore how connections with the study of the deaths of massive stars may further our understanding of open issues in galaxy evolution.

  9. Starbursts From 30 Doradus to Lyman Break Galaxies

    Grijs, Richard

    2005-01-01

    Starbursts are important features of early galaxy evolution. Many of the distant, high-redshift galaxies we are able to detect are in a starbursting phase, often apparently provoked by a violent gravitational interaction with another galaxy. In fact, if we did not know that major starbursts existed, these conference proceedings testify that we would indeed have difficulties explaining the key properties of the Universe! These conference proceedings cover starbursts from the small-scale star-forming regions in nearby galaxies to galaxy-wide events at high redshifts; one of the major themes of the conference proved to be "scalability", i.e., can we scale up the small-scale events to describe the physics on larger scales. The key outcome of this meeting – and these proceedings – is a resounding "yes" as answer to this fundamental, yet profound question. The enhanced synergy facilitated by the collaboration among observers using cutting-edge ground and space-based facilities, theorists and modellers has made ...

  10. Starbursts and Galaxy Evolution: results from COSMOS survey.

    Muñoz-Tuñón, C.; Hinojosa Goñi, R.; Jairo Méndez Abreu, J.; Sánchez Alméida, J.

    2016-06-01

    The search for starbursts galaxies in COSMOS database by a tailored procedure that uses the photometry from SUBARU, results in 220 targets at zsimilar to that of the quiescent galaxies in the survey at the same redshift range. From the detailed analysis of the galaxies images using the HST, the star forming clumps are characterized. The galaxies are of three different kinds, Snot, Snot and diffuse light and multiple knots. The mass of the knots are typically one order of magnitude below that of the host galaxy and the clumps in multiple knot galaxies are bigger the closer they are to the center. The sSFR however does not change with the particular position of the burst in their host galaxy, which suggests a similar process independently of their location. This result applies also to the galaxies at the largest z range (0.9). Our interpretation is that the star formation is happening at all possible locations on the galaxy discs, possibly from gas accreted from the halo or the IGM, with clumps which grow as they spiral and get to the centermost regions. Our previous work on nearby SF -tadpole galaxies of similar mass reported metallicity drops coinciding with the location of the burst what we have interpreted as SF driven by cold flows. Our results in COSMOS would be consistent with a similar interpretation and a scenario in which medium mass disks are growing by gas accretion that show up as scattered starbursts knots.

  11. Mapping CS in Starburst Galaxies: Disentangling and Characterising Dense Gas

    Kelly, G; Bayet, E; Aladro, R; Yates, J

    2015-01-01

    Aims. We observe the dense gas tracer CS in two nearby starburst galaxies to determine how the conditions of the dense gas varies across the circumnuclear regions in starburst galaxies. Methods. Using the IRAM-30m telescope, we mapped the distribution of the CS(2-1) and CS(3-2) lines in the circumnuclear regions of the nearby starburst galaxies NGC 3079 and NGC 6946. We also detected the formaldehyde (H2CO) and methanol (CH3OH) in both galaxies. We marginally detect the isotopologue C34S. Results. We calculate column densities under LTE conditions for CS and CH3OH. Using the detections accumulated here to guide our inputs, we link a time and depth dependent chemical model with a molecular line radiative transfer model; we reproduce the observations, showing how conditions where CS is present are likely to vary away from the galactic centres. Conclusions. Using the rotational diagram method for CH3OH, we obtain a lower limit temperature of 14 K. In addition to this, by comparing the chemical and radiative tran...

  12. Dense circum-nuclear molecular gas in starburst galaxies

    Green, Claire-Elise; Green, James A; Dawson, Joanne R; Jones, Paul A; López-Sánchez, Ángel R; Verdes-Montenegro, Lourdes; Henkel, Christian; Baan, Willem A; Martín, Sergio

    2016-01-01

    We present results from a study of the dense circum-nuclear molecular gas of starburst galaxies. The study aims to investigate the interplay between starbursts, active galactic nuclei and molecular gas. We characterise the dense gas traced by HCN, HCO$^{+}$ and HNC and examine its kinematics in the circum-nuclear regions of nine starburst galaxies observed with the Australia Telescope Compact Array. We detect HCN (1$-$0) and HCO$^{+}$ (1$-$0) in seven of the nine galaxies and HNC (1$-$0) in four. Approximately 7 arcsec resolution maps of the circum-nuclear molecular gas are presented. The velocity integrated intensity ratios, HCO$^{+}$ (1$-$0)/HCN (1$-$0) and HNC (1$-$0)/HCN (1$-$0), are calculated. Using these integrated intensity ratios and spatial intensity ratio maps we identify photon dominated regions (PDRs) in NGC 1097, NGC 1365 and NGC 1808. We find no galaxy which shows the PDR signature in only one part of the observed nuclear region. We also observe unusually strong HNC emission in NGC 5236, but it...

  13. H Emission Line Morphologies in Markarian Starburst Galaxies

    A. Chitre; U. C. Joshi

    2001-06-01

    We present broad band and narrow band H emission line images of a sample of optically selected starburst galaxies from the Markarian lists. The emission line morphology is studied and global properties like luminosities, equivalent widths and star formation rates are derived. The radial distribution of H flux and the EW are determined using concentric aperture photometry on the emission line and the continuum images. H flux is generally found to peak in the nuclear region and fall off outwards. The EW is found to peak off-center in most of the cases implying that though the intensity of emission is maximum at the nucleus, the star formation activity relative to the underlying continuum often peaks away from the center in Markarian starburst galaxies.

  14. The environments of starburst and post-starburst galaxies at z=0.4-0.8

    Poggianti, Bianca M; Zaritsky, Dennis; De Lucia, Gabriella; Milvang-Jensen, Bo; Desai, Vandana; Jablonka, Pascale; Halliday, Claire; Rudnick, Gregory; Varela, Jesus; Bamford, Steven; Best, Philip; Clowe, Douglas; Noll, Stefan; Saglia, Roberto; Pello, Roser; Simard, Luc; von der Linden, Anja; White, Simon

    2008-01-01

    Post-starburst (E+A or k+a) spectra, characterized by their exceptionally strong Balmer lines in absorption and the lack of emission lines, belong to galaxies in which the star formation activity ended abruptly sometime during the past Gyr. We perform a spectral analysis of galaxies in clusters, groups, poor groups and the field at z=0.4-0.8 based on the ESO Distant Cluster Survey. The incidence of k+a's at these redshifts depends strongly on environment. K+a's reside preferentially in clusters and, unexpectedly, in a subset of the sigma = 200-400 km/s groups, those that have a low fraction of [OII] emitters. In these environments, 20-30% of the recently star-forming galaxies have had their star formation activity recently truncated. In contrast, there are proportionally fewer k+a's in the field, the poor groups and groups with a high [OII] fraction. The incidence of k+a galaxies correlates with the cluster velocity dispersion: more massive clusters have higher proportions of k+a's. Spectra of dusty starburst...

  15. Infrared line ratios revealing starburst conditions in galaxies

    Viegas, S M M; Contini, T; Viegas, Sueli M.; Contini, Marcella; Contini, Thierry

    1999-01-01

    The physical conditions in typical starburst galaxies are investigated through critical infrared (IR) line ratios, as previously suggested by Lutz et al. (1998, A&A, 333, L75). The calculations by a composite model which consistently accounts for the coupled effect of shock and photoionization by hot stars definitely fit the observed line ratios of single objects and explain the observed relation between [OIV]/([NeII]+0.44[NeIII]) and [NeIII]/[NeII]. The shock velocity and the gas density are the critical parameters. Most of the shocks are produced in low density-velocity (n_0 = 100 cm-3 and V_s = 50 - 100 km/s) clouds which represent the bulk of the ionized gas in starburst galaxies. However, though they are by many orders less numerous, high-velocity (= 400 - 600 km/s) shocks in dense (= 500 - 800 cm-3) clouds are necessary to reproduce the critical IR line ratios observed in the low-excitation Starburst Nucleus Galaxies (SBNGs: M82, M83, NGC 253, NGC 3256, NGC 3690, and NGC 4945). These model predictio...

  16. Chandra Images the Seething Cauldron of Starburst Galaxy

    2000-01-01

    NASA's Chandra X-ray Observatory has imaged the core of the nearest starburst galaxy, Messier 82 (M82). The observatory has revealed a seething cauldron of exploding stars, neutron stars, black holes, 100 million degree gas, and a powerful galactic wind. The discovery will be presented by a team of scientists from Carnegie Mellon University, Pittsburgh, Penn., Pennsylvania State University, University Park, and the University of Michigan, Ann Arbor, on January 14 at the 195th national meeting of the American Astronomical Society. "In the disk of our Milky Way Galaxy, stars form and die in a relatively calm fashion like burning embers in a campfire," said Richard Griffiths, Professor of Astrophysics at Carnegie Mellon University. "But in a starburst galaxy, star birth and death are more like explosions in a fireworks factory." Short-lived massive stars in a starburst galaxy produce supernova explosions, which heat the interstellar gas to millions of degrees, and leave behind neutron stars and black holes. These explosions emit light in the X rays rather than in visible light. Because the superhot components inside starburst galaxies are complex and sometimes confusing, astronomers need an X-ray-detecting telescope with the highest focusing power (spatial resolution) to clearly discriminate the various structures. "NASA's Chandra X-ray Observatory is the perfect tool for studying starburst galaxies since it has the critical combination of high-resolution optics and good sensitivity to penetrating X rays," said Gordon Garmire, the Evan Pugh Professor of Astronomy and Astrophysics at Pennsylvania State University, and head of the team that conceived and built Chandra's Advanced CCD Imaging Spectrograph (ACIS) X-ray camera, which acquired the data. Many intricate structures missed by earlier satellite observatories are now visible in the ACIS image, including more than twenty powerful X-ray binary systems that contain a normal star in a close orbit around a neutron star

  17. A statistical study of properties of Seyfert and starburst galaxies

    Dahari, Oved; De Robertis, Michael M.

    1988-01-01

    Spectral and morphological data for 282 Seyfert and emission-line galaxies spanning radio to X-ray wavelengths are compiled. The data include a large number of optical emission-line measurements which have not been reported previously. These data are intended to provide a convenient summary of the relevant properties of these galaxies, as well as a data base to search for correlations among the various parameters in order to obtain a better understanding of the active galaxy phenomenon. The paper presents the data and analyzes the distributions of various properties of Seyfert 1 and Seyfert 2 galaxies and starburst galaxies. It is found that Seyferts 2s have a higher 60 micron/forbidden O III 5007 A flux ratio than Seyfert 1s. This result, combined with the fact that Seyfert 2s are more heavily reddened, indicate that they have a higher dust content. It is also found that starburst nuclei are comparable to Seyfert 2s in far-infrared and 20 cm luminosities, although their optical spectra are markedly different.

  18. Statistical study of properties of Seyfert and starburst galaxies

    Dahari, O.; De Robertis, M.M.

    1988-07-01

    Spectral and morphological data for 282 Seyfert and emission-line galaxies spanning radio to X-ray wavelengths are compiled. The data include a large number of optical emission-line measurements which have not been reported previously. These data are intended to provide a convenient summary of the relevant properties of these galaxies, as well as a data base to search for correlations among the various parameters in order to obtain a better understanding of the active galaxy phenomenon. The paper presents the data and analyzes the distributions of various properties of Seyfert 1 and Seyfert 2 galaxies and starburst galaxies. It is found that Seyferts 2s have a higher 60 micron/forbidden O III 5007 A flux ratio than Seyfert 1s. This result, combined with the fact that Seyfert 2s are more heavily reddened, indicate that they have a higher dust content. It is also found that starburst nuclei are comparable to Seyfert 2s in far-infrared and 20 cm luminosities, although their optical spectra are markedly different. 116 references.

  19. Statistical study of properties of Seyfert and starburst galaxies

    Spectral and morphological data for 282 Seyfert and emission-line galaxies spanning radio to X-ray wavelengths are compiled. The data include a large number of optical emission-line measurements which have not been reported previously. These data are intended to provide a convenient summary of the relevant properties of these galaxies, as well as a data base to search for correlations among the various parameters in order to obtain a better understanding of the active galaxy phenomenon. The paper presents the data and analyzes the distributions of various properties of Seyfert 1 and Seyfert 2 galaxies and starburst galaxies. It is found that Seyferts 2s have a higher 60 micron/forbidden O III 5007 A flux ratio than Seyfert 1s. This result, combined with the fact that Seyfert 2s are more heavily reddened, indicate that they have a higher dust content. It is also found that starburst nuclei are comparable to Seyfert 2s in far-infrared and 20 cm luminosities, although their optical spectra are markedly different. 116 references

  20. The Ubiquity of Coeval Starbursts in Massive Galaxy Cluster Progenitors

    Casey, Caitlin M

    2016-01-01

    The Universe's largest galaxy clusters likely built the majority of their massive $>10^{11} M_\\odot$ galaxies in simultaneous, short-lived bursts of activity well before virialization. This conclusion is reached from emerging datasets on $z>2$ proto-clusters and the characteristics of their member galaxies, in particular, rare starbursts and ultraluminous active galactic nuclei (AGN). The most challenging observational hurdle in identifying such structures is their very large volumes, $\\sim10^{4}$ comoving Mpc$^3$ at $z>2$, subtending areas $\\sim$half a degree on the sky. Thus the contrast afforded by an overabundance of very rare galaxies in comparison to the background can more easily distinguish overdense structures from the surrounding, normal density field. Five $210^{15} M_\\odot$ galaxy clusters in the nearby Universe, a factor of five larger than expected in some simulations. Some tension yet exists between measurements of their volume density of starburst-rich proto-clusters and the expectation that t...

  1. Winds of change: reionization by starburst galaxies

    Sharma, Mahavir; Frenk, Carlos; Bower, Richard G; Crain, Robert A; Schaller, Matthieu; Schaye, Joop

    2016-01-01

    We investigate the properties of the galaxies that reionized the Universe and the history of cosmic reionization using the "Evolution and Assembly of GaLaxies and their environments" (EAGLE) cosmological hydrodynamical simulations. We obtain the evolution of the escape fraction of ionizing photons in galaxies assuming that galactic winds create channels through which 20~percent of photons escape when the local surface density of star formation is greater than $0.1$ M$_\\odot$ yr$^{-1}$ kpc$^{-2}$. Such threshold behaviour for the generation of winds is observed, and the rare local objects which have such high star formation surface densities exhibit high escape fractions. In our model the luminosity-weighted mean escape fraction increases with redshift as $\\bar f_{\\rm esc}=0.045~((1+z)/4)^{1.1}$ at $z>3$, and the galaxy number weighted mean as $\\langle f_{\\rm esc} \\rangle=2.2\\times10^{-3}~((1+z)/4)^4$, and becomes constant $\\approx0.2$ at redshift $z>10$. The escape fraction evolves as an increasingly large fr...

  2. Starbursts in Isolated Galaxies: the influence of the ISM model

    Theis, Christian

    2009-01-01

    We study the stability properties of isolated star forming dwarf galaxies which undergo dynamically driven starbursts induced by stellar feedback. Here we focus on the impact of the adopted ISM model, i.e. either a diffuse or a clumpy ISM. We apply a one-zone model extended for active dynamical evolution. We found two major types of repetitive star bursts: one set (type A) of quasi-periodic starbursts is related to the dynamical timescale of the galaxy. In that case, the star formation follows the variations of the gas density induced by decaying virial oscillations. The second set (type B) of starbursts is characterized by long quiescence periods given by the sum of the dynamical and the dissipative timescale: after a first burst, the inserted energy leads to a substantial expansion of the system, by this stopping any significant star formation activity. A next burst might occur, when the gas reaches high densities again, i.e. after the gas recollapsed and the energy injected by stellar feedback is dissipate...

  3. Chemical Properties of Starburst Galaxies Near and Far: Clues to Galaxy Evolution

    Contini, T.; Treyer, M. -A.; Mouhcine, M.; Sullivan, M.; Ellis, R. S.,

    2001-01-01

    The determination of chemical abundances in star-forming galaxies and the study of their evolution on cosmological timescales are powerful tools for understanding galaxy formation and evolution. This contribution presents the latest results in this domain. We show that detailed studies of chemical abundances in UV-selected, HII and starburst nucleus galaxies, together with the development of new chemical evolution models, put strong constraints on the evolutionary stage of these objects in te...

  4. The rest-frame optical morphology of starburst galaxies at 1 < z < 3.5

    Lee, Bomee; Giavalisco, Mauro; Candels, Goods-Hershcel

    2015-01-01

    Using CANDELS combined with GOODS-Herschel in the GOODS-North and South field, we investigate the rest-frame optical morphologies of starburst galaxies at 1 We compare morphologies of MS and SB galaxies using non-parametric (Sersic Index) and parametric measures as well as the visual identification. FIR luminous starburst galaxies are usually interpreted as major wet mergers. We find that the average morphologies of SB galaxies are disky and generally have much more diffuse optical light profile than massive compact early-type galaxies (ETGs), challenging gas-rich merging as the primary dissipative mechanism to assemble very compact, massive galaxies. We find that the sizes of the SB galaxies are clearly larger than those of the MS galaxies on average. NIR to MIR colors of starburst galaxies show no evidence of highly dust-obscured compact component, which could eventually emerge as the massive compact core. Very compact SB galaxies are rather rare, and hence even from a statistical standpoint, our morphological analysis of starburst galaxies does not support the popular mechanism that powerful starburst in a highly dissipative wet merger of gas-rich disks, and subsequent quenching, is the key driver behind the formation of the massive, compact early-type galaxies observed at z~2. The light distribution of the bulk of stars in starburst galaxies is simply not compact enough to eventually evolve into the massive ultra compact ETGs at high redshift universe.

  5. Properties of the Molecular Gas in Starburst Galaxies and AGN

    Mühle, S; Henkel, C

    2009-01-01

    There is growing evidence that the properties of the molecular gas in the nuclei of starburst galaxies and in AGN may be very different from those seen in Galactic star forming regions and that a high kinetic temperature in the molecular gas may lead to a non-standard initial mass function in the next generation of stars. Unfortunately, among the fundamental parameters derived from molecular line observations, the kinetic temperature of the molecular gas in external galaxies is often not well determined due to a lack of suitable tracer molecules. We discuss the diagnostic power of selected transition lines of formaldehyde (H_2CO), which can be used as a molecular thermometer as well as an excellent tracer of the molecular gas density. As a proof of concept, we present the results of our multi-transition line study of the H_2CO emission from the prototypical starburst galaxy M82. Using our large velocity gradient model, we tightly constrain the physical properties of the dense gas in the prominent molecular lo...

  6. On the Lyman-alpha Emission of Starburst Galaxies

    Valls-Gabaud, D

    1993-01-01

    Nearby starburst galaxies have consistently shown anomalous Ly-alpha/H-beta ratios. By re-analysing the published IUE/optical observations, we show that most starbursts present a normal Ly-alpha emission, consistent with case B recombination theory, provided extinction laws appropriate to their metallicities are used. This implies that extinction is more important than multiple resonant scattering effects. The anomalous emission and absorption lines present in a few remaining galaxies are simply explained if they are observed in the post-burst phase, between about 10$^7$ and 10$^8$ yrs after the start of the burst. We use updated stellar population synthesis models to show that anomalous ratios are produced by the aging of stellar populations, since the underlying stellar Ly-alpha line is important in the cooler massive stars. The inferred low-duty cycle of massive star formation accounts naturally for the failure to detect large numbers of Ly-alpha--emitting galaxies in deep surveys and at high redshift. Som...

  7. THE IMACS CLUSTER BUILDING SURVEY. V. FURTHER EVIDENCE FOR STARBURST RECYCLING FROM QUANTITATIVE GALAXY MORPHOLOGIES

    Using J- and Ks-band imaging obtained as part of the IMACS Cluster Building Survey (ICBS), we measure Sérsic indices for 2160 field and cluster galaxies at 0.31 < z < 0.54. Using both mass- and magnitude-limited samples, we compare the distributions for spectroscopically determined passive, continuously star-forming, starburst, and post-starburst systems and show that previously established spatial and statistical connections between these types extend to their gross morphologies. Outside of cluster cores, we find close structural ties between starburst and continuously star-forming, as well as post-starburst and passive types, but not between starbursts and post-starbursts. These results independently support two conclusions presented in Paper II of this series: (1) most starbursts are the product of a non-disruptive triggering mechanism that is insensitive to global environment, such as minor mergers; (2) starbursts and post-starbursts generally represent transient phases in the lives of 'normal' star-forming and quiescent galaxies, respectively, originating from and returning to these systems in closed 'recycling' loops. In this picture, spectroscopically identified post-starbursts constitute a minority of all recently terminated starbursts, largely ruling out the typical starburst as a quenching event in all but the densest environments

  8. DLA kinematics and outflows from starburst galaxies

    Razoumov, Alexei O

    2008-01-01

    We present results from a numerical study of the multiphase interstellar medium in sub-Lyman-break galaxy protogalactic clumps. Such clumps are abundant at z=3 and are thought to be a major contributor to damped Ly-alpha absorption. We model the formation of winds from these clumps and show that during star formation episodes they feature outflows with neutral gas velocity widths up to several hundred km/s. Such outflows are consistent with the observed high-velocity dispersion in DLAs. In our models thermal energy feedback from winds and supernovae results in efficient outflows only when cold (~ 300 K), dense (> 100 msun/pc^3) clouds are resolved at grid resolution of 12 pc. At lower 24 pc resolution the first signs of the multiphase medium are spotted; however, at this low resolution thermal injection of feedback energy cannot yet create hot expanding bubbles around star-forming regions -- instead feedback tends to erase high-density peaks and suppress star formation. At 12 pc resolution feedback compresses...

  9. Contribution from normal and starburst galaxies to the extragalactic gamma-ray background (EGRB)

    Debbijoy Bhattacharya; Parameswaran Sreekumar

    2009-01-01

    The extragalactic diffuse emission at γ-ray energies has interesting cosmo-logical implications since these photons suffer little or no attenuation during their prop-agation from the site of origin. The emission could originate from either truly diffuse processes or from unresolved point sources such as AGNs, normal galaxies and starburst galaxies. Here, we examine the unresolved point source origin of the extragalactic γ-ray background emission from normal galaxies and starburst galaxies. γ-ray emission from normal galaxies is primarily coming from cosmic-ray interactions with interstellar mat-ter and radiation (~90%) along with a small contribution from discrete point sources (~10%). Starburst galaxies are expected to have enhanced supernovae activity which leads to higher cosmic-ray densities, making starburst galaxies sufficiently luminous at γ-ray energies to be detected by the current γ-ray mission (Fermi Gamma-ray Space Telescope).

  10. Local starburst galaxies and their descendants. Statistics from the Sloan Digital Sky Survey

    Bergvall, Nils; Marquart, Thomas; Way, Michael J.; Blomqvist, Anna; Holst, Emma; Östlin, Göran; Zackrisson, Erik

    2016-03-01

    Aims: Despite strong interest in the starburst phenomenon in extragalactic astronomy, the concept remains ill-defined. Here we use a strict definition of starburst to examine the statistical properties of starburst galaxies in the local universe. We also seek to establish links between starburst galaxies, post-starburst (hereafter postburst) galaxies, and active galaxies. Methods: Data were selected from the Sloan Digital Sky Survey DR7. We applied a novel method of treating dust attenuation and derive star formation rates, ages, and stellar masses assuming a two-component stellar population model. Dynamical masses are calculated from the width of the Hα line. These masses agree excellently with the photometric masses. The mass (gas+stars) range is ~109-1011.5ℳ⊙. As a selection criterion for starburst galaxies, we use, the birthrate parameter, b = SFR/ ⟨ SFR ⟩, requiring that b ≥ 3. For postburst galaxies, we use, the equivalent width of Hδ in absorption with the criterion EWHδ,abs ≥ 6 Å. Results: We find that only 1% of star-forming galaxies are starburst galaxies. They contribute 3-6% to the stellar production and are therefore unimportant for the local star formation activity. The median starburst age is 70 Myr roughly independent of mass, indicating that star formation is mainly regulated by local feedback processes. The b-parameter strongly depends on burst age. Values close to b = 60 are found at ages ~10 Myr, while almost no starbursts are found at ages >1 Gyr. The median baryonic burst mass fraction of sub-L∗ galaxies is 5% and decreases slowly towards high masses. The median mass fraction of the recent burst in the postburst sample is 5-10%. A smaller fraction of the postburst galaxies, however, originates in non-bursting galaxies. The age-mass distribution of the postburst progenitors (with mass fractions >3%) is bimodal with a break at logℳ(ℳ⊙) ~ 10.6, above which the ages are doubled. The starburst and postburst luminosity

  11. The Radio–Gamma Correlation in Starburst Galaxies

    Eichmann, B.; Becker Tjus, J.

    2016-04-01

    We present a systematic study of non-thermal electron–proton plasma and its emission processes in starburst galaxies in order to explain the correlation between the luminosity in the radio band and the recently observed gamma luminosity. In doing so, a steady state description of the cosmic-ray (CR) electrons and protons within the spatially homogeneous starburst is considered where continuous momentum losses are included as well as catastrophic losses due to diffusion and advection. The primary source of the relativistic CRs, e.g., supernova remnants, provides a quasi-neutral plasma with a power-law spectrum in momentum where we account for rigidity-dependent differences between the electron and proton spectrum. We examine the resulting leptonic and hadronic radiation processes by synchrotron radiation, inverse Compton scattering, Bremsstrahlung, and hadronic pion production. Finally, the observations of NGC 253, M82, NGC 4945, and NGC 1068 in the radio and gamma-ray bands as well as the observed supernova rate are used to constrain a best-fit model. In the case of NGC 253, M82, and NGC 4945 our model is able to accurately describe the data, showing that: (i) supernovae are the dominant particle accelerators for NGC 253, M82, and NGC 4945, but not for NGC 1068; (ii) all considered starburst galaxies are poor proton calorimeters in which for NGC 253 the escape is predominantly driven by the galactic wind, whereas the diffusive escape dominates in NGC 4945 and M82 (at energies >1 TeV); and (iii) secondary electrons from hadronic pion production are important to model the radio flux, but the associated neutrino flux is below the current observation limit.

  12. THE DRIVING MECHANISM OF STARBURSTS IN GALAXY MERGERS

    We present hydrodynamic simulations of a major merger of disk galaxies, and study the interstellar medium (ISM) dynamics and star formation (SF) properties. High spatial and mass resolutions of 12 pc and 4 x 104 M sun allow us to resolve cold and turbulent gas clouds embedded in a warmer diffuse phase. We compare lower-resolution models, where the multiphase ISM is not resolved and is modeled as a relatively homogeneous and stable medium. While merger-driven bursts of SF are generally attributed to large-scale gas inflows toward the nuclear regions, we show that once a realistic ISM is resolved, the dominant process is actually gas fragmentation into massive and dense clouds and rapid SF therein. As a consequence, SF is more efficient by a factor of up to ∼10 and is also somewhat more extended, while the gas density probability distribution function rapidly evolves toward very high densities. We thus propose that the actual mechanism of starburst triggering in galaxy collisions can only be captured at high spatial resolution and when the cooling of gas is modeled down to less than 103 K. Not only does our model reproduce the properties of the Antennae system, but it also explains the 'starburst mode' recently revealed in high-redshift mergers compared to quiescent disks.

  13. AGN outflows trigger starbursts in gas-rich galaxies

    Zubovas, Kastytis; King, Andrew; Wilkinson, Mark

    2013-01-01

    Recent well resolved numerical simulations of AGN feedback have shown that its effects on the host galaxy may be not only negative but also positive. In the late gas poor phase, AGN feedback blows the gas away and terminates star formation. However, in the gas-rich phase(s), AGN outflows trigger star formation by over-compressing cold dense gas and thus provide positive feedback on their hosts. In this paper we study this AGN-triggered starburst effect. We show that star formation rate in the burst increases until the star formation feedback counteracts locally the AGN outflow compression. Globally, this predicts a strong nearly linear statistical correlation between the AGN and starburst bolometric luminosities in disc galaxies, L_* \\propto L_{AGN}^{5/6}. The correlation is statistical only because AGN activity may fluctuate on short time scales (as short as tens of years), and because AGN may turn off but its effects on the host may continue to last until the AGN-driven outflow leaves the host, which may be...

  14. Starbursts and dusty tori in distant 3CR radio galaxies

    Podigachoski, P; Barthel, P D; Drouart, G; Fioc, M

    2016-01-01

    We present a study of the complete ultraviolet to submillimetre spectral energy distributions (SEDs) of twelve 3CR radio galaxy hosts in the redshift range $1.0 < z < 2.5$, which were all detected in the far-infrared by the Herschel Space Observatory. The study employs the new spectro-chemical evolutionary code P\\'EGASE.3, in combination with recently published clumpy AGN torus models. We uncover the properties of the massive host galaxy stellar populations, the AGN torus luminosities, and the properties of the recent starbursts, which had earlier been inferred in these objects from their infrared SEDs. The P\\'EGASE.3 fitting yields very luminous (up to 10$^{13}$L$_{\\odot}$) young stellar populations with ages of several hundred million years in hosts with masses exceeding 10$^{11}$M$_{\\odot}$. Dust masses are seen to increase with redshift, and a surprising correlation -- or better upper envelope behaviour -- is found between the AGN torus luminosity and the starburst luminosity, as revealed by their a...

  15. STAR CLUSTER DISRUPTION IN THE STARBURST GALAXY MESSIER 82

    Using high-resolution, multiple-passband Hubble Space Telescope images spanning the entire optical/near-infrared wavelength range, we obtained a statistically complete U-band-selected sample of 846 extended star clusters across the disk of the nearby starburst galaxy M82. Based on a careful analysis of the clusters' spectral energy distributions, we determined their galaxy-wide age and mass distributions. The M82 clusters exhibit three clear peaks in their age distribution, thus defining relatively young, log (t yr–1) ≤ 7.5, intermediate-age, log (t yr–1) in [7.5, 8.5], and old samples, log (t yr–1) ≥ 8.5. Comparison of the completeness-corrected mass distributions offers a firm handle on the galaxy's star cluster disruption history. The most massive star clusters in the young and old samples are (almost) all concentrated in the most densely populated central region, while the intermediate-age sample's most massive clusters are more spatially dispersed, which may reflect the distribution of the highest-density gas throughout the galaxy's evolutionary history, combined with the solid-body nature of the galaxy's central region

  16. The evolution of the cold interstellar medium in galaxies following a starburst

    Rowlands, K; Nesvadba, N; Sibthorpe, B; Mortier, A; Lehnert, M; da Cunha, E

    2014-01-01

    We present the evolution of dust and molecular gas properties in a sample of 11 $z\\sim0.03$ starburst to post-starburst (PSB) galaxies selected to span an age sequence from ongoing starburst to 1 Gyr after the starburst ended. All PSBs harbour significant molecular gas and dust reservoirs and residual star formation, indicating that complete quenching of the starburst due to exhaustion or expulsion of gas has not occurred during this timespan. As the starburst ages, we observe a clear decrease in the star-formation efficiency, molecular gas and SFR surface density, and effective dust temperature, from levels coincident with starburst galaxies to those of normal star-forming galaxies. These trends are consistent with a natural decrease in the SFR following consumption of molecular gas by the starburst, and corresponding decrease in the interstellar radiation field strength as the starburst ages. The gas and dust contents of the PSBs are coincident with those of star-forming galaxies and molecular gas-rich earl...

  17. Star cluster disruption in the starburst galaxy Messier 82

    Li, Shuo; Anders, Peter; Li, Chengyuan

    2014-01-01

    Using high-resolution, multiple-passband Hubble Space Telescope images spanning the entire optical/near-infrared wavelength range, we obtained a statistically complete sample, $U$-band selected sample of 846 extended star clusters across the disk of the nearby starburst galaxy M82. Based on careful analysis of their spectral energy distributions, we determined their galaxy-wide age and mass distributions. The M82 clusters exhibit three clear peaks in their age distribution, thus defining a relatively young, log(t/yr) 8.5. Comparison of the completeness-corrected mass distributions offers a firm handle on the galaxy's star cluster disruption history. The most massive star clusters in the young and old samples are (almost) all concentrated in the most densely populated central region, while the intermediate-age sample's most massive clusters are more spatially dispersed, which may reflect the distribution of the highest-density gas throughout the galaxy's evolutionary history, combined with the solid-body natu...

  18. Simulations of galactic winds and starbursts in galaxy clusters

    Kapferer, W; Domainko, W; Mair, M; Kronberger, T; Schindler, S; Kimeswenger, S; Van Kampen, E; Breitschwerdt, D; Ruffert, M

    2005-01-01

    We present an investigation of the metal enrichment of the intra-cluster medium (ICM) by galactic winds and merger-driven starbursts. We use combined N-body/hydrodynamic simulations with a semi-numerical galaxy formation model. The mass loss by galactic winds is obtained by calculating transonic solutions of steady state outflows, driven by thermal, cosmic ray and MHD wave pressure. The inhomogeneities in the metal distribution caused by these processes are an ideal tool to reveal the dynamical state of a galaxy cluster. We present surface brightness, X-ray emission weighted temperature and metal maps of our model clusters as they would be observed by X-ray telescopes like XMM-Newton. We show that X-ray weighted metal maps distinguish between pre- or post-merger galaxy clusters by comparing the metallicity distribution with the galaxy-density distribution: pre-mergers have a metallicity gap between the subclusters, post-mergers a high metallicity between subclusters. We apply our approach to two observed gala...

  19. The Radio-Gamma Correlation In Starburst Galaxies

    Eichmann, Björn

    2015-01-01

    We present a systematic study of the non-thermal electron-proton plasma and its emission processes in starburst galaxies in order to explain the correlation between the luminosity in the radio band and the recently observed gamma luminosity. In doing so, a steady state description of the non-thermal electrons and protons within the spatially homogeneous starburst is considered where continuous momentum losses are included as well as catastrophic losses due to diffusion and advection. The primary source of the relativistic electron-proton plasma, e.g. supernova remnants, provides a quasi-neutral plasma with a power law spectrum in momentum where we account for rigidity dependent differences between the electron and proton spectrum. We examine the resulting leptonic and hadronic radiation processes by synchrotron radiation, inverse Compton scattering, Bremsstrahlung and hadronic pion production. Finally, the observations of NGC 253, M 82, NGC 4945 and NGC 1068 in the radio and gamma-ray band are used to constra...

  20. CONNECTIONS BETWEEN GALAXY MERGERS AND STARBURST: EVIDENCE FROM THE LOCAL UNIVERSE

    Major mergers and interactions between gas-rich galaxies with comparable masses are thought to be the main triggers of starburst. In this work, we study, for a large stellar mass range, the interaction rate of the starburst galaxies in the local universe. We focus independently on central and satellite star forming galaxies extracted from the Sloan Digital Sky Survey. Here the starburst galaxies are selected in the star formation rate (SFR) stellar mass plane with SFRs five times larger than the median value found for ''star forming'' galaxies of the same stellar mass. Through visual inspection of their images together with close companions determined using spectroscopic redshifts, we find that ∼50% of the ''starburst'' populations show evident merger features, i.e., tidal tails, bridges between galaxies, double cores, and close companions. In contrast, in the control sample we selected from the normal star forming galaxies, only ∼19% of galaxies are associated with evident mergers. The interaction rates may increase by ∼5% for the starburst sample and 2% for the control sample if close companions determined using photometric redshifts are considered. The contrast of the merger rate between the two samples strengthens the hypothesis that mergers and interactions are indeed the main causes of starburst

  1. Resolving The Generation of Starburst Winds in Galaxy Mergers

    Hopkins, Philip F; Murray, Norman; Hernquist, Lars; Narayanan, Desika; Hayward, Christopher C

    2013-01-01

    We study galaxy super-winds driven in major mergers, using pc-resolution simulations with detailed models for stellar feedback that can self-consistently follow the formation/destruction of GMCs and generation of winds. The models include molecular cooling, star formation at high densities in GMCs, and gas recycling and feedback from SNe (I&II), stellar winds, and radiation pressure. We study mergers of systems from SMC-like dwarfs and Milky Way analogues to z~2 starburst disks. Multi-phase super-winds are generated in all passages, with outflow rates up to ~1000 M_sun/yr. However, the wind mass-loading efficiency (outflow rate divided by SFR) is similar to that in isolated galaxy counterparts of each merger: it depends more on global galaxy properties (mass, size, escape velocity) than on the dynamical state of the merger. Winds tend to be bi- or uni-polar, but multiple 'events' build up complex morphologies with overlapping, differently-oriented bubbles/shells at a range of radii. The winds have complex...

  2. Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy

    Geach, J E; Diamond-Stanic, A M; Krips, M; Rudnick, G H; Tremonti, C A; Sell, P H; Coil, A L; Moustakas, J

    2014-01-01

    Recent observations have revealed that starburst galaxies can drive molecular gas outflows through stellar radiation pressure. Molecular gas is the phase of the interstellar medium from which stars form, so these outflows curtail stellar mass growth in galaxies. Previously known outflows, however, involve small fractions of the total molecular gas content and are restricted to sub-kiloparsec scales. It is also apparent that input from active galactic nuclei is in at least some cases dynamically important, so pure stellar feedback has been considered incapable of aggressively terminating star formation on galactic scales. Extraplanar molecular gas has been detected in the archetype starburst galaxy M82, but so far there has been no evidence that starbursts can propel significant quantities of cold molecular gas to the same galactocentric radius (~10 kpc) as the warmer gas traced by metal absorbers. Here we report observations of molecular gas in a compact (effective radius 100 pc) massive starburst galaxy at z...

  3. The identification of post-starburst galaxies at z~1 using multiwavelength photometry: a spectroscopic verification

    Maltby, David T; Wild, Vivienne; Hatch, Nina A; Hartley, William G; Simpson, Chris; McLure, Ross J; Dunlop, James; Rowlands, Kate; Cirasuolo, Michele

    2016-01-01

    Despite decades of study, we still do not fully understand why some massive galaxies abruptly switch off their star formation in the early Universe, and what causes their rapid transition to the red sequence. Post-starburst galaxies provide a rare opportunity to study this transition phase, but few have currently been spectroscopically identified at high redshift ($z>1$). In this paper we present the spectroscopic verification of a new photometric technique to identify post-starbursts in high-redshift surveys. The method classifies the broad-band optical-near--infrared spectral energy distributions (SEDs) of galaxies using three spectral shape parameters (super-colours), derived from a principal component analysis of model SEDs. When applied to the multiwavelength photometric data in the UKIDSS Ultra Deep Survey (UDS), this technique identified over 900 candidate post-starbursts at redshifts $0.55 Ang.) and Balmer break, characteristic of post-starburst galaxies. We conclude that photometric methods can be us...

  4. The IMACS Cluster Building Survey: V. Further Evidence for Starburst Recycling from Quantitative Galaxy Morphologies

    Abramson, Louis E; Gladders, Michael D; Oemler,, Augustus; Poggianti, Bianca M; Monson, Andrew; Persson, Eric; Vulcani, Benedetta

    2013-01-01

    Using J and K_s band imaging obtained as part of the IMACS Cluster Building Survey (ICBS) we measure S\\'ersic indices for 2160 field and cluster galaxies at 0.31 < z < 0.54. We compare the distributions for spectroscopically determined passive, continuously starforming, starburst, and poststarburst systems and show that previously established spatial/statistical connections between these types extend to their gross morphologies. Outside of cluster cores, we find close structural ties between starburst and continuously starforming, as well as poststarburst and passive types, but not between starbursts and poststarbursts. These results independently support two conclusions presented in a previous ICBS paper (Dressler et al.): 1) most starbursts are the product of a non-disruptive triggering mechanism that is insensitive to global environment, such as minor-mergers; 2) starbursts and poststarbursts largely represent transient phases in the lives of "normal" starforming and quiescent galaxies, respectively,...

  5. HAWK-I infrared supernova search in starburst galaxies

    Miluzio, M; Botticella, M T; Cresci, G; Greggio, L; Mannucci, F; Benetti, S; Bufano, F; Elias-Rosa, N; Pastorello, A; Turatto, M; Zampieri, L

    2013-01-01

    The use of SN rates to probe explosion scenarios and to trace the cosmic star formation history received a boost from a number of synoptic surveys. There has been a recent claim of a mismatch by a factor of two between star formation and core collapse SN rates, and different explanations have been proposed for this discrepancy.} We attempted an independent test of the relation between star formation and supernova rates in the extreme environment of starburst galaxies, where both star formation and extinction are extremely high. To this aim we conducted an infrared supernova search in a sample of local starburts galaxies. The rational to search in the infrared is to reduce the bias due to extinction, which is one of the putative reasons for the observed discrepancy between star formation and supernova rates. To evaluate the outcome of the search we developed a MonteCarlo simulation tool that is used to predict the number and properties of the expected supernovae based on the search characteristics and the curr...

  6. Aspects of the interstellar medium in starburst galaxies

    Fanelli, Michael N.

    1990-07-01

    Researchers are engaged in a multifaceted program to investigate the stellar content and star formation history of actively star-forming galaxies. A large body of stellar spectra have been examined to identify spectral features characteristic of specific stellar types. These spectral diagnostics are then calibrated in terms of temperature (spectral type), gravity (luminosity class) and metallicity. The spectral data is compiled into a stellar library whose members represent specific locations in the HR diagram. Through the use of population synthesis techniques, both optimizing and evolutionary approaches, the stellar luminosity function in composite populations can be determined by analysis of their integrated light. Researchers have concentrated on the ultraviolet wavelength region (lambda lambda 1200 to 3200), utilizing the International Ultraviolet Explorer (IUE) archives supplemented by additional observations. In the optical, virtually all stars will contribute to the integrated light. In the ultraviolet however, cool stars will produce negligible flux due to their steep ultraviolet-to-visual continua, greatly simplifying the investigation of the hot component in a composite population. The researchers' initial stellar library has been applied to several blue compact galaxies, (BCGs), a class of starburst galaxy which is UV luminous. BCGs possess a complex interstellar medium which affects the emergent stellar continuum in several ways. This presents a challenge to the stellar analysis but affords insight into the properties of the gas and dust from which the massive OB stars have formed. The optimizing synthesis method solves for the stellar luminosity function and extinction simultaneously. This therefore provides an independent measure of the extinction affecting the hot population component. Despite the rise of the reddening law towards the ultraviolet, BCGs are found to be brighter in the ultraviolet than expected.

  7. Aspects of the interstellar medium in starburst galaxies

    Researchers are engaged in a multifaceted program to investigate the stellar content and star formation history of actively star-forming galaxies. A large body of stellar spectra have been examined to identify spectral features characteristic of specific stellar types. These spectral diagnostics are then calibrated in terms of temperature (spectral type), gravity (luminosity class) and metallicity. The spectral data is compiled into a stellar library whose members represent specific locations in the HR diagram. Through the use of population synthesis techniques, both optimizing and evolutionary approaches, the stellar luminosity function in composite populations can be determined. Researchers have concentrated on the ultraviolet wavelength region (lambda lambda 1200 to 3200). In the optical, virtually all stars will contribute to the integrated light. In the ultraviolet however, cool stars will produce negligible flux due to their steep ultraviolet-to-visual continua, greatly simplifying the investigation of the hot component in a composite population. The researchers' initial stellar library has been applied to several blue compact galaxies, (BCGs), a class of starburst galaxy which is UV luminous. BCGs possess a complex interstellar medium which affects the emergent stellar continuum in several ways. This presents a challenge to the stellar analysis but affords insight into the properties of the gas and dust from which the massive OB stars have formed. The optimizing synthesis method solves for the stellar luminosity function and extinction simultaneously. This therefore provides an independent measure of the extinction affecting the hot population component. Despite the rise of the reddening law towards the ultraviolet, BCGs are found to be brighter in the ultraviolet than expected

  8. The Evolution of Post-Starburst Galaxies from z~1 to the Present

    Pattarakijwanich, Petchara; Ho, Shirley; Ross, Nicholas P

    2014-01-01

    Post-starburst galaxies are in the transitional stage between blue, star-forming galaxies and red, quiescent galaxies, and therefore hold important clues for our understanding of galaxy evolution. In this paper, we systematically searched for and identified a large sample of post-starburst galaxies from the spectroscopic dataset of the Sloan Digital Sky Survey (SDSS) Data Release 9. In total, we found more than 6000 objects with redshifts between z ~ 0.05 to z ~ 1.3, making this the largest sample of post-starburst galaxies in the literature. We calculated the luminosity function of the post-starburst galaxies using two uniformly selected subsamples: the SDSS Main Galaxy Sample and the Baryon Oscillation Spectroscopic Survey CMASS sample. The luminosity functions are roughly log-normal. The peak magnitudes shift as a function of redshift from M ~ -23.5 at z ~ 0.8 to M ~ -20.5 at z ~ 0.1. This is consistent with the downsizing trend, whereby higher mass galaxies form earlier than low-mass galaxies. We compared...

  9. ACA [CI] observations of the starburst galaxy NGC 253

    Krips, M.; Martín, S.; Sakamoto, K.; Aalto, S.; Bisbas, T. G.; Bolatto, A. D.; Downes, D.; Eckart, A.; Feruglio, Ch.; García-Burillo, S.; Geach, J.; Greve, T. R.; König, S.; Matsushita, S.; Neri, R.; Offner, S.; Peck, A. B.; Viti, S.; Wagg, J.

    2016-07-01

    Context. Carbon monoxide (CO) is widely used as a tracer of the molecular gas in almost all types of environments. However, several shortcomings of CO complicate usaging it as H2 tracer, such as its optical depth effects, the dependence of its abundance on metallicity, or its susceptibility to dissociation in highly irradiated regions. Neutral carbon emission has been proposed to overcome some of these shortcomings and hence to help revealing the limits of CO as a measure of the molecular gas. Aims: We aim to study the general characteristics of the spatially and spectrally resolved carbon line emission in a variety of extragalactic sources and evaluate its potential as complementary H2 tracer to CO. Methods: We used the Atacama Compact Array to map the [CI](3P1-3P0) line emission in the nearby starburst galaxy NGC 253 at unprecedented angular resolution (~3''). This is the first well-resolved interferometric [CI] map of an extragalactic source. Results: We have detected the [CI] line emission at high significance levels along the central disk of NGC 253 and its edges where expanding shells have previously been found in CO. Globally, the distribution of the [CI] line emission strongly resembles that of CO, confirming the results of previous Galactic surveys that [CI] traces the same molecular gas as CO. However, we also identify a significant increase of [CI] line emission with respect to CO in (some of) the outflow or shocked regions of NGC 253, namely the bipolar outflow emerging from the nucleus. A first-order estimate of the [CI] column densities indicates abundances of [CI] that are very similar to the abundance of CO in NGC 253. Interestingly, we find that the [CI] line is marginally optically thick within the disk. Conclusions: The enhancement of the [CI]/CO line ratios (~0.4-0.6) with respect to Galactic values (≤0.1), especially in the shocked regions of NGC 253, clearly indicates that mechanical perturbation such as shocks and the strong radiation

  10. Chronos and Kairos: Mosfire Observations of Post-Starburst Galaxies in z~1 Clusters and Groups

    Lemaux, Brian C; Lubin, Lori M; Wu, Po-Feng; Gal, Roy R; Rumbaugh, Nicholas; Kocevski, Dale D; Squires, amd Gordon K

    2016-01-01

    In this study we present the exploration of $\\sim$500 spectroscopically confirmed galaxies in and around two large scale structures at $z\\sim1$ drawn from the ORELSE survey. A sub-sample of these galaxies ($\\sim$150) were targeted for the initial phases of a near-infrared MOSFIRE spectroscopic campaign investigating the differences in selections of galaxies which had recently ended a burst of star formation or had rapidly quenched (i.e., post-starburst or K+A galaxies). Selection with MOSFIRE resulted in a post-starburst sample more than double that selected by traditional $z\\sim1$ (observed-frame optical) methods even after the removal of the relatively large fraction of dusty starburst galaxies selected through traditional methods. While the traditional post-starburst fraction increased with increased global density, the MOSFIRE-selected post-starburst fraction was found to be constant in field, group, and cluster environments. However, this fraction relative to the number of galaxies with ongoing star form...

  11. Local starburst galaxies and their descendants. Statistics from the Sloan Digital Sky Survey

    Bergvall, Nils; Marquart, Thomas; Way, Michael J.; Blomqvist, Anna; Holst, Emma; Ostlin, Goran; Zackrisson, Erik

    2016-01-01

    Despite strong interest in the starburst phenomenon in extragalactic astronomy, the concept remains ill-defined. Here we use a strict definition of starburst to examine the statistical properties of starburst galaxies in the local universe. We also seek to establish links between starburst galaxies, post-starburst (hereafter postburst) galaxies, and active galaxies. Data were selected from the Sloan Digital Sky Survey DR7. We applied a novel method of treating dust attenuation and derive star formation rates, ages, and stellar masses assuming a two-component stellar population model. Dynamical masses are calculated from the width of the H-alpha line. These masses agree excellently with the photometric masses. The mass (gas+stars) range is approximately 10( exp 9) - 10(exp 11.5) solar mass. As a selection criterion for starburst galaxies, we use, the birthrate parameter, b = SFR/SFR, requiring that b is greater than 3. For postburst galaxies, we use, the equivalent width of Hdelta in absorption with the criterion EW (sub Hdelta_abs) is greater than 6 A. Results. We find that only 1% of star-forming galaxies are starburst galaxies. They contribute 3-6% to the stellar production and are therefore unimportant for the local star formation activity. The median starburst age is 70 Myr roughly independent of mass, indicating that star formation is mainly regulated by local feedback processes. The b-parameter strongly depends on burst age. Values close to b = 60 are found at ages approximately 10 Myr, while almost no starbursts are found at ages greater than 1 Gyr. The median baryonic burst mass fraction of sub-L galaxies is 5% and decreases slowly towards high masses. The median mass fraction of the recent burst in the postburst sample is 5-10%. A smaller fraction of the postburst galaxies, however, originates in non-bursting galaxies. The age-mass distribution of the postburst progenitors (with mass fractions is greater than 3%) is bimodal with a break at logM(solar mass

  12. Discovery of Large Molecular Gas Reservoirs in Post-Starburst Galaxies

    French, K Decker; Zabludoff, Ann; Narayanan, Desika; Shirley, Yancy; Walter, Fabian; Smith, John-David; Tremonti, Christy A

    2015-01-01

    Post-starburst (or "E+A") galaxies are characterized by low H$\\alpha$ emission and strong Balmer absorption, suggesting a recent starburst, but little current star formation. Although many of these galaxies show evidence of recent mergers, the mechanism for ending the starburst is not yet understood. To study the fate of the molecular gas, we search for CO (1-0) and (2-1) emission with the IRAM 30m and SMT 10m telescopes in 32 nearby ($0.01starburst galaxies drawn from the Sloan Digital Sky Survey. We detect CO in 17 (53%). Using CO as a tracer for molecular hydrogen, and a Galactic conversion factor, we obtain molecular gas masses of $M(H_2)=10^{8.6}$-$10^{9.8} M_\\odot$ and molecular gas mass to stellar mass fractions of $\\sim10^{-2}$-$10^{-0.5}$, comparable to those of star-forming galaxies. The large amounts of molecular gas rule out complete gas consumption, expulsion, or starvation as the primary mechanism that ends the starburst in these galaxies. The upper limits on $M(H_2)$ for th...

  13. The SDSS Discovery of a Strongly Lensed Post-Starburst Galaxy at z=0.766

    Shin, Min-Su; Strauss, Michael A.; Oguri, Masamune; Inada, Naohisa; Emilio E. Falco; Broadhurst, Tom; Gunn, James E.

    2008-01-01

    We present the first result of a survey for strong galaxy-galaxy lenses in Sloan Digital Sky Survey (SDSS) images. SDSS J082728.70+223256.4 was selected as a lensing candidate using selection criteria based on the color and positions of objects in the SDSS photometric catalog. Follow-up imaging and spectroscopy showed this object to be a lensing system. The lensing galaxy is an elliptical at z = 0.349 in a galaxy cluster. The lensed galaxy has the spectrum of a post-starburst galaxy at z = 0....

  14. The Post-Starburst Evolution of Tidal Disruption Event Host Galaxies

    French, K Decker; Zabludoff, Ann

    2016-01-01

    Tidal Disruption Events (TDEs) favor quiescent host galaxies with strong Balmer absorption lines. Here we study eight hosts of optical/UV-detected TDEs to determine the duration of the recent star formation episode, the time elapsed since it ended, and the fraction of stellar mass produced. Most hosts (6/8) have had short recent starbursts of <200 Myr as opposed to a slower decline in star formation. TDE host galaxies span a wide range of post-starburst ages (60-600 Myr for 6/8 galaxies), indicating that TDEs are not limited to a specific time in their hosts' post-starburst evolution. If the disrupted star was a main sequence star that formed in the burst or before, the post-burst ages provide an independent constraint on its likely mass, excluding O, B and the most massive A stars. If the starburst arose from a galaxy merger, the time elapsed since the starburst began constrains the coalescence timescale and thus limits the merger mass ratio to more equal than 12:1 in most (7/8) TDE hosts. This uncommon r...

  15. X-ray emission of post-starburst galaxies: looking into the feedback mechanism

    Ballo, Lucia

    2011-11-01

    The tight relation between galaxy bulges and black holes shows that star formation and accretion must have co-evolved throughout the history of the Universe. The leading hypothesis is that intense periods of star formation and black hole growth concurrently occur in the history of massive galaxies, possibly triggered by mergers. The feedback from the AGN could terminate the star formation and, eventually, extinguish the AGN itself. The complex physics involved in such a scenario is, however, poorly understood. The best class of objects to investigate the relative time-scales of this feedback are the post-starburst galaxies, i.e. galaxies observed shortly after the star-formation has ended (about 0.1-1 Gyr). ~0.3% of the SDSS galaxies in the local Universe show evidence in the optical band of the presence of both a nucleus still accreting in their centre and a post-starburst signature. This suggests that the switching off for a starburst event occurs before the extinguishing of the nuclear activity. However, it is not clear whether this result is a common law in the feedback mechanisms. Here we present a project devoted to study the X-ray emission of the apparently quiescent post-starburst galaxies detected in the SDSS, to deeply investigate the real lack of nuclear activity (possibly obscured in the optical band), and to study the energetics of these systems.

  16. Starbursts Lessons for the Origin and Evolution of Galaxies and the Inter-Galactic Medium

    Heckman, T M

    1997-01-01

    Starbursts are episodes of intense star-formation that occur in the central regions of galaxies, and dominate the integrated emission from the galaxy. They are a significant component of the present- day universe, being the site of for testing our ideas about star-formation, the evolution of high-mass stars, and the physics of the interstellar medium. They serve as local analogs of the processes that were important in the origin and early evolution of galaxies and in the heating and chemical enrichment of the inter-galactic medium. In this contribution I review starbursts from this broad cosmogonical perspective, stressing several key lessons we have learned from starbursts: 1) Violent, transient events play a significant role in the origin and evolution of galaxies. 2) Galaxies do not evolve as `Island Universes': starbursts are triggered by galaxy interactions and produce outflows of hot chemically-enriched gas that `pollute' the inter- galactic medium. 3) Dust dramatically affects of view of high-mass star...

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

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

    2012-01-01

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

  18. STAR FORMATION RATES FOR STARBURST GALAXIES FROM ULTRAVIOLET, INFRARED, AND RADIO LUMINOSITIES

    We present a comparison of star formation rates (SFR) determined from mid-infrared 7.7 μm polycyclic aromatic hydrocarbon (PAH) luminosity [SFR(PAH)], from 1.4 GHz radio luminosity [SFR(radio)], and from far-ultraviolet luminosity [SFR(UV)] for a sample of 287 starburst galaxies with z ν(7.7 μm)] - 42.57 ± 0.2, for SFR in Msun yr-1 and νL ν(7.7 μm) the luminosity at the peak of the 7.7 μm PAH feature in erg s-1, is found to agree with SFR(radio). Comparing with SFR(UV) determined independently from ultraviolet observations of the same sources with the Galaxy Evolution Explorer mission (not corrected for dust extinction), the median log [SFR(PAH)/SFR(UV)] = 1.67, indicating that only 2% of the ultraviolet continuum typically escapes extinction by dust within a starburst. This ratio SFR(PAH)/SFR(UV) depends on infrared luminosity, with the form log [SFR(PAH)/SFR(UV)] = (0.53 ± 0.05)log [νLν(7.7 μm)] - 21.5 ± 0.18, indicating that more luminous starbursts are also dustier. Using our adopted relation between νLν(7.7 μm) and L ir, this becomes log [SFR(PAH)/SFR(UV)]= (0.53 ± 0.05)log Lir - 4.11 ± 0.18, for Lir in Lsun. Only blue compact dwarf galaxies show comparable or greater SFR(UV) compared to SFR(PAH). We also find that the ratio SFR(PAH)/SFR(UV) is similar to that in infrared-selected starbursts for a sample of Markarian starburst galaxies originally selected using optical classification, which implies that there is no significant selection effect in SFR(PAH)/SFR(UV) using starburst galaxies discovered by Spitzer. These results indicate that SFRs determined with ultraviolet luminosities require dust corrections by a factor of ∼10 for typical local starbursts but this factor increases to >700 for the most luminous starbursts at z ∼ 2.5. Application of this factor explains why the most luminous starbursts discovered by Spitzer at z ∼ 2.5 are optically faint; with this amount of extinction, the optical magnitude of a starburst having fν(7.7

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

    Using star formation histories derived from optically resolved stellar populations in 19 nearby starburst dwarf galaxies observed with the Hubble Space Telescope, we measure the stellar mass surface densities of stars newly formed in the bursts. By assuming a star formation efficiency (SFE), we then calculate the inferred gas surface densities present at the onset of the starbursts. Assuming an SFE of 1%, as is often assumed in normal star-forming galaxies, and assuming that the gas was purely atomic, translates to very high H I surface densities (∼102-103 M☉ pc–2), which are much higher than have been observed in dwarf galaxies. This implies either higher values of SFE in these dwarf starburst galaxies or the presence of significant amounts of H2 in dwarfs (or both). Raising the assumed SFEs to 10% or greater (in line with observations of more massive starbursts associated with merging galaxies), still results in H I surface densities higher than observed in 10 galaxies. Thus, these observations appear to require that a significant fraction of the gas in these dwarf starbursts galaxies was in the molecular form at the onset of the bursts. Our results imply molecular gas column densities in the range 1019-1021 cm–2 for the sample. In the galaxies where CO observations have been made, these densities correspond to values of the CO–H2 conversion factor (XCO) in the range >(3-80) × 1020 cm–2 (K km s–1)–1, or up to 40 × greater than Galactic XCO values.

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

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

    2012-06-01

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

  1. Starburst Intensity Limit of Galaxies at z simeq 5-6

    Hathi, N. P.; Malhotra, S.; Rhoads, J. E.

    2008-02-01

    The peak star formation intensity in starburst galaxies does not vary significantly from the local universe to redshift z ~ 6. We arrive at this conclusion through new surface brightness measurements of 47 starburst galaxies at z simeq 5-6, doubling the redshift range for such observations. These galaxies are spectroscopically confirmed in the Hubble Ultra Deep Field (HUDF) through the GRism ACS program for Extragalactic Science (GRAPES) project. The starburst intensity limit for galaxies at z simeq 5-6 agrees with those at z simeq 3-4 and z simeq 0 to within a factor of a few, after correcting for cosmological surface brightness dimming and for dust. The most natural interpretation of this constancy over cosmic time is that the same physical mechanisms limit starburst intensity at all redshifts up to z simeq 6 (be they galactic winds, gravitational instability, or something else). We do see two trends with redshift: First, the UV spectral slope (β) of galaxies at z simeq 5-6 is bluer than that of z simeq 3 galaxies, suggesting an increase in dust content over time. Second, the galaxy sizes from z simeq 3 to 6 scale approximately as the Hubble parameter H-1(z) . Thus, galaxies at z simeq 6 are high-redshift starbursts, much like their local analogs except for slightly bluer colors, smaller physical sizes, and correspondingly lower overall luminosities. If we now assume a constant maximum star formation intensity, the differences in observed surface brightness between z simeq 0 and 6 are consistent with standard expanding cosmology and strongly inconsistent with the tired light model.

  2. Constraints on dark energy from H II starburst galaxy apparent magnitude versus redshift data

    In this Letter we use H II starburst galaxy apparent magnitude versus redshift data from Siegel et al. (2005) to constrain dark energy cosmological model parameters. These constraints are generally consistent with those derived using other data sets, but are not as restrictive as the tightest currently available constraints.

  3. Starburst or Seyfert? Adding a radio and far-infrared perspective to the investigation of activity in composite galaxies

    Hill, T L; Norris, R P; Reynolds, J E; Hunstead, R W; Hill, Tanya L.; Heisler, Charlene A.; Norris, Ray P.; Reynolds, John E.; Hunstead, Richard W.

    2001-01-01

    It was once common to regard Seyfert and starburst galaxies as completely different types of object, but there is growing recognition that these classifications refer to the extremes of a continuous spectrum of galaxy types. In a previous study we investigated a sample of galaxies with ambiguous optical emission-line ratios and concluded from near-infrared spectroscopic observations that the sample consisted of composite galaxies, containing both a starburst and an active galactic nucleus (AGN). We now extend our study using radio synthesis and long-baseline interferometer observations made with the Australia Telescope, together with far-infrared IRAS observations, to discuss the relative contribution of starburst and AGN components to the overall luminosity of the composite galaxies. We find that only a small fraction of the radio emission (90%) is probably due to the starburst component. We also show that an AGN contribution to the optical emission of as little as 10% is sufficient to account for the ambigu...

  4. Star(bursts) of FIRE: observational signatures of bursty star formation in galaxies

    Sparre, Martin; Feldmann, Robert; Faucher-Giguère, Claude-André; Muratov, Alexander L; Kereš, Dušan; Hopkins, Philip F

    2015-01-01

    Galaxy formation models exhibit remarkable success in reproducing observed relations such as the relation between galaxies' star formation rates (SFRs) and stellar masses and the stellar mass--halo mass relation. We demonstrate that comparisons of the short-timescale variability in galaxy SFRs with observational data provide an additional useful constraint on the physics of galaxy formation feedback. We apply SFR indicators with different sensitivity timescales to galaxies from the Feedback in Realistic Environments (FIRE) simulations. We find that the SFR--stellar mass relation has a significantly greater scatter when the Halpha-derived SFR is considered compared with when the far-ultraviolet (FUV)-based SFR is used. This difference is a direct consequence of bursty star formation because the FIRE galaxies exhibit order-of-magnitude SFR variations over timescales of a few Myr. Consequently, low-mass galaxies can go through both quenched (in terms of the 10-Myr averaged SFR) and starburst phases within a 200-...

  5. A connection between star formation activity and cosmic rays in the starburst galaxy M 82

    Acciari, V A; Arlen, T; Aune, T; Bautista, M; Beilicke, M; Benbow, W; Boltuch, D; Bradbury, S M; Buckley, J H; Bugaev, V; Byrum, K; Cannon, A; Celik, O; Cesarini, A; Chow, Y C; Ciupik, L; Cogan, P; Colin, P; Cui, W; Dickherber, R; Duke, C; Fegan, S J; Finley, J P; Finnegan, G; Fortin, P; Fortson, L; Furniss, A; Galante, N; Gall, D; Gibbs, K; Gillanders, G H; Godambe, S; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Holder, J; Horan, D; Hui, C M; Humensky, T B; Imran, A; Kaaret, Philip; Karlsson, N; Kertzman, M; Kieda, D; Kildea, J; Konopelko, A; Krawczynski, H; Krennrich, F; Lang, M J; Le Bohec, S; Maier, G; McArthur, S; McCann, A; McCutcheon, M; Millis, J; Moriarty, P; Mukherjee, R; Nagai, T; Ong, R A; Otte, A N; Pandel, D; Perkins, J S; Pizlo, F; Pohl, M; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Rose, H J; Schroedter, M; Sembroski, G H; Smith, A W; Steele, D; Swordy, S P; Theiling, M; Thibadeau, S; Varlotta, A; Vasilev, V V; Vincent, S; Wagner, R G; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; Weisgarber, T; Williams, D A; Wissel, S; Wood, M; Zitzer, B; 10.1038/nature08557

    2009-01-01

    Although Galactic cosmic rays (protons and nuclei) are widely believed to be dominantly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery [1]. The active regions of starburst galaxies have exceptionally high rates of star formation, and their large size, more than 50 times the diameter of similar Galactic regions, uniquely enables reliable calorimetric measurements of their potentially high cosmic-ray density [2]. The cosmic rays produced in the formation, life, and death of their massive stars are expected to eventually produce diffuse gamma-ray emission via their interactions with interstellar gas and radiation. M 82, the prototype small starburst galaxy, is predicted to be the brightest starburst galaxy in gamma rays [3, 4]. Here we report the detection of >700 GeV gamma rays from M 82. From these data we determine a cosmic-ray density of 250 eV cm-3 in the starburst core of M 82, or about 500 times the averag...

  6. Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: IV The Controlling Parameters of the Starburst SED

    Groves, B; Sutherland, R; Kewley, L; Fischera, J; Leitherer, C; Brandl, B; van Breugal, W

    2007-01-01

    We combine the the stellar spectral synthesis code Starburst99, the nebular modelling code MAPPINGSIII, and a 1-D dynamical evolution model of HII regions around massive clusters of young stars to generate improved models of the spectral energy distribution (SED) of starburst galaxies. We introduce a compactness parameter, C, which characterizes the specific intensity of the radiation field at ionization fronts in HII regions, and which controls the shape of the far-IR dust re-emission, often referred to loosely as the dust ``temperature''. We also investigate the effect of metallicity on the overall SED and in particular, on the strength of the PAH features. We provide templates for the mean emission produced by the young compact HII regions, the older (10 - 100 Myr) stars and for the wavelength-dependent attenuation produced by a foreground screen of the dust used in our model. We demonstrate that these components may be combined to produce a excellent fit to the observed SEDs of star formation dominated ga...

  7. New constraints on the escape of ionizing photons from starburst galaxies using ionization-parameter mapping

    The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [S III]/[S II] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrowband images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40° ± 5° (0.4 sr), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble activity, which should be conducive to escaping radiation, yet they are optically thick. These results support the scenario that an orientation bias limits our ability to directly detect escaping Lyman continuum in many starburst galaxies. A comparison of the star formation properties and histories of the optically thin and thick galaxies is consistent with the model that high escape fractions are limited to galaxies that are old enough (≳3 Myr) for mechanical feedback to have cleared optically thin passageways in the interstellar medium, but young enough (≲5 Myr) that the ionizing stars are still present.

  8. Post-Starburst Galaxies: Why Aren't They Forming Stars?

    de Rijcke, S.; Buyle, P.; Pisano, D. J.; Freeman, K.; Dejonghe, H.

    2010-06-01

    We present high spatial resolution 21 cm HI observations of EA01A and EA01B, a pair of interacting post-starburst, PSG or E+A, galaxies at z = 0.0746. Based on optical HST/WFPC2 images, both galaxies are known to display disturbed morphologies. They also appear to be linked by a bridge of stars. Previous HI observations [1] had already uncovered sizable quantities of neutral gas in or near these galaxies but they lacked the spatial resolution to locate the gas with any precision within this galactic binary system. We have analysed deep, high resolution archival VLA observations of the couple. We find evidence for three gaseous tidal tails; one connected to EA01A and two emanating from EA01B. These findings confirm, independently from the optical imaging, that (i) EA01A and EA01B are actively interacting, and that, as a consequence, the starbursts that occurred in these galaxies were most likely triggered by this interaction, and that (ii) 6.6+/-0.9×109 Msolar of neutral gas are still present in the immediate vicinity of the optical bodies of both galaxies. The HI column density is lowest at the optical positions of the galaxies, suggesting that most of the neutral gas that is visible in our maps is associated with the tidal arms and not with the galaxies themselves. This might provide an explanation for the apparent lack of ongoing star formation in these galaxies.

  9. Optical spectroscopy of the radio-loud nuclei of spiral galaxies: Starbursts or monsters

    We present optical spectroscopic data pertaining to the physical state, kinematics, and spatial extent of the emission-line gas near the radio-loud nuclei of spiral galaxies. These data are combined with published optical, radio, and infrared data to evaluate the suggestions by Condon et al. (1982) that the nuclear radio emission in this class of galaxy is produced by multiple supernova remnants generated as a consequence of a nuclear starburst. As a whole, the radio-loud nuclei have stronger emission lines than radio-quiet nuclei of galaxies of similar Hubble/de Vaucouleurs type. This emission-line gas is generally at least as spatially extended as the radio continuum emission. However, we find that only about 1/3 of the spiral galaxies examined have optical spectroscopic properties consistent with those of ''extranuclear starbursts'' (i.e., giant H II regions). The majority of the nuclei seem to require a form of energy input to the ionized gas which is ''harder'' than the Lyman continuum radiation of OB stars, as their emission-line spectra are of the Seyfert or Liner variety. The nuclei with H II region spectra are distinct from the nuclei with Seyfert spectra in terms of radio morphology and radio spectral index, and tend to occur in spiral galaxies of much later Hubble type than do the Seyfert or Liner nuclei (Sc vs Sa). Moreover, the most luminous nuclear radio sources in our sample (PMHz> or =1022 Watts Hz-1 Sr-1) are not associated with H II region nuclei. We summarize evidence that the putative nuclear starbursts must differ significantly from extranuclear starbursts

  10. Galaxies probing galaxies: cool halo gas from a z = 0.47 post-starburst galaxy

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

    2009-01-01

    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 16.5/h_70 kpc. The background galaxy spectrum reveals strong FeII, MgII, MgI, and CaII absorption at the redshift of the foreground galaxy, with a MgII 2796 rest equivalent width of 3.93 +/- 0.08 Angstroms, indicative of a velocity width exceeding 400 km/s. Because the background galaxy is large (> 4/h_70 kpc), the high covering fr...

  11. How ubiquitous are massive starbursts in interacting galaxies?

    Di Matteo, P; Martig, M; Combes, F; Melchior, A -L; Semelin, B

    2009-01-01

    Many evidences exist for a connection between galaxy interactions and induced star formation. However, a large range of responses of galaxies to tidal interactions is found, both in observations and in numerical simulations. We will discuss some recent results obtained analysing a large sample (~ 1000) of simulations of interacting pairs and their agreement with the most recent observational works.

  12. Very deep IRAS survey - constraints on the evolution of starburst galaxies

    Counts of sources (primarily starburst galaxies) from a deep 60 microns IRAS survey published by Hacking and Houck (1987) are compared with four evolutionary models. The counts below 100 mJy are higher than expected if no evolution has taken place out to a redshift of approximately 0.2. Redshift measurements of the survey sources should be able to distinguish between luminosity-evolution and density-evolution models and detect as little as a 20 percent brightening or increase in density of infrared sources per billion years ago (H/0/ = 100 km/s per Mpc). Starburst galaxies cannot account for the reported 100 microns background without extreme evolution at high redshifts. 21 references

  13. Localized starbursts in dwarf galaxies produced by impact of low metallicity cosmic gas clouds

    Almeida, J Sanchez; Munoz-Tunon, C; Elmegreen, D M; Perez-Montero, E; Amorin, R; Filho, M E; Ascasibar, Y; Papaderos, P; Vilchez, J M

    2015-01-01

    Models of galaxy formation predict that gas accretion from the cosmic web is a primary driver of star formation over cosmic history. Except in very dense environments where galaxy mergers are also important, model galaxies feed from cold streams of gas from the web that penetrate their dark matter haloes. Although these predictions are unambiguous, the observational support has been indirect so far. Here we report spectroscopic evidence for this process in extremely metal-poor galaxies (XMPs) of the local Universe, taking the form of localized starbursts associated with gas having low metallicity. Detailed abundance analyses based on Gran Telescopio Canarias (GTC) optical spectra of ten XMPs show that the galaxy hosts have metallicities around 60 % solar on average, while the large star-forming regions that dominate their integrated light have low metallicities of some 6 % solar. Because gas mixes azimuthally in a rotation timescale (a few hundred Myr), the observed metallicity inhomogeneities are only possib...

  14. Stellar population gradients and spatially resolved kinematics in luminous post-starburst galaxies

    Pracy, M B; Sadler, E; Couch, W J; Kuntschner, H; Bekki, K; Owers, M S; Zwaan, M; Turner, J; Bergmann, M

    2013-01-01

    We have used deep integral field spectroscopy obtained with the GMOS instrument on Gemini-North to determine the spatial distribution of the post-starburst stellar population in four luminous E+A galaxies at z<0.04. We find all four galaxies have centrally-concentrated gradients in the young stellar population contained within the central ~1 kpc. This is in agreement with the Balmer line gradients found in local low luminosity E+A galaxies. The results from higher redshift (z~0.1) samples of luminous E+A galaxies have been varied, but in general have found the post-starburst signature to be extended or a galaxy-wide phenomenon or have otherwise failed to detect gradients in the stellar populations. The ubiquity of the detection of a centrally concentrated young stellar population in local samples, and the presence of significant radial gradients in the stellar populations when the E+A galaxy core is well resolved raises the possibility that spatial resolution issues may be important in interpreting the hig...

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

    Buffie, Kaitlynn; Heesen, Volker; Shalchi, Andreas

    2012-01-01

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

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

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

    2001-01-01

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

  17. High-resolution radio observations of nuclear and circumnuclear starbursts in Luminous Infrared Galaxies

    Perez-Torres, Miguel A

    2008-01-01

    High-resolution radio observations of nearby starburst galaxies have shown that the distribution of their radio emission consists of a compact (<150 pc), high surface brightness, central radio source immersed in a low surface brightness circumnuclear halo. This radio structure is similar to that detected in bright Seyferts galaxies like NGC 7469 or Mrk 331, which display clear circumnuclear rings. While the compact, centrally located radio emission in these starbursts might be generated by a point-like source (AGN), or by the combined effect of multiple radio supernovae and supernova remnants (e.g., the evolved nuclear starburst in Arp~220), it seems well established that the circumnuclear regions of those objects host an ongoing burst of star-formation (e.g., NGC 7469; Colina et al. 2001, Alberdi et al. 2006). Therefore, high-resolution radio observations of Luminous Infra-Red Galaxies (LIRGs) in our local universe are a powerful tool to probe the dominant dust heating mechanism in their nuclear and circu...

  18. New Constraints on the Escape of Ionizing Photons From Starburst Galaxies Using Ionization-Parameter Mapping

    Zastrow, Jordan; Veilleux, Sylvain; McDonald, Michael

    2013-01-01

    The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [SIII]/[SII] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrow-band images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40+/-5 degrees (0.4 ster), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble act...

  19. Class I methanol megamasers: a potential probe of starburst activity and feedback in active galaxies

    Chen, X.; Ellingsen, S. P.; Zhang, J.-S.; Wang, J.-Z.; Shen, Z.-Q.; Wu, Q.-W.; Wu, Z.-Z.

    2016-06-01

    Previous observations have shown that the distribution of 36.2-GHz class I methanol megamaser (MM) emission in Arp 220 is highly correlated with the diffuse X-rays. On this basis it was suggested that methanol MM may be produced either by the effects of galactic-outflow-driven shocks and/or cosmic rays. Here we report the results of a single-dish survey undertaken with the Greenbank Telescope (GBT) to improve our understanding of the pumping conditions of extragalactic class I methanol masers and their relationship to starburst and feedback processes within the host galaxies, towards a sample which includes 16 galaxies which show both extended soft X-ray emission, and either OH or H2O MM emission. Large baseline ripples in the GBT spectra limited our results to tentative detections towards 11 of the target galaxies. Analysis of these tentative detections shows that there are significant correlations between the methanol intensity and the host-galaxy infrared, radio and OH MM emission, but no correlation with the X-ray and H2O MM emission. Some sources show methanol emission significantly offset from the systemic velocity of the galaxy (by up to 1000 km s-1) and we propose that these are associated with galactic-scale outflows from active galactic nuclei (AGNs) feedback. The combined observational properties suggest that class I methanol MMs are related to significant starburst and molecular outflow activity and hence may provide a potential probe of AGN feedback and starburst processes in the host galaxies.

  20. From HI to Stars: HI Depletion in Starbursts and Star-Forming Galaxies in the ALFALFA H-alpha Survey

    Jaskot, A E; Salzer, J J; Van Sistine, A; Bell, E F; Haynes, M P

    2015-01-01

    HI in galaxies traces the fuel for future star formation and reveals the effects of feedback on neutral gas. Using a statistically uniform, HI-selected sample of 565 galaxies from the ALFALFA H-alpha survey, we explore HI properties as a function of star formation activity. ALFALFA H-alpha provides R-band and H-alpha imaging for a volume-limited subset of the 21-cm ALFALFA survey. We identify eight starbursts based on H-alpha equivalent width and six with enhanced star formation relative to the main sequence. Both starbursts and non-starbursts have similar HI to stellar mass ratios (MHI/M*), which suggests that feedback is not depleting the starbursts' HI. Consequently, the starbursts do have shorter HI depletion times (t_dep), implying more efficient HI-to-H2 conversion. While major mergers likely drive this enhanced efficiency in some starbursts, the lowest mass starbursts may experience periodic bursts, consistent with enhanced scatter in t_dep at low M*. Two starbursts appear to be pre-coalescence mergers...

  1. The SDSS Discovery of a Strongly Lensed Post-Starburst Galaxy at z=0.766

    Shin, Min-Su; Strauss, Michael A.; Oguri, Masamune; Inada, Naohisa; Falco, Emilio E.; Broadhurst, Tom; Gunn, James E.

    2008-09-30

    We present the first result of a survey for strong galaxy-galaxy lenses in Sloan Digital Sky Survey (SDSS) images. SDSS J082728.70+223256.4 was selected as a lensing candidate using selection criteria based on the color and positions of objects in the SDSS photometric catalog. Follow-up imaging and spectroscopy showed this object to be a lensing system. The lensing galaxy is an elliptical at z = 0.349 in a galaxy cluster. The lensed galaxy has the spectrum of a post-starburst galaxy at z = 0.766. The lensing galaxy has an estimated mass of {approx} 1.2 x 10{sup 12} M{sub {circle_dot}} and the corresponding mass to light ratio in the B-band is {approx} 26 M{sub {circle_dot}}/L{sub {circle_dot}} inside 1.1 effective radii of the lensing galaxy. Our study shows how catalogs drawn from multi-band surveys can be used to find strong galaxy-galaxy lenses having multiple lens images. Our strong lensing candidate selection based on photometry-only catalogs will be useful in future multi-band imaging surveys such as SNAP and LSST.

  2. Starburst Galaxies: Hard X-ray spectra and contribution to the diffuse background

    Gruber, Duane E.

    1993-01-01

    During the period of this grant two main tasks were performed: a determination of a selection criterion for starburst galaxies most likely to emit X-rays, and performance of a pilot study of the X-ray emission from nine such systems. Starburst galaxies may be expected to emit flat-spectrum X-ray at energies above 10 keV resulting from the various remnants of the short-lived massive stars which characterize the starburst. The investigation to determine the optimum sample resulted in a change from an X-ray selected (HEAO-2) sample to infrared selection based on the IRAS catalogue. A much broader sample thereby available for study, and selection could be limited to only the nearest objects and still obtain a reasonably large sample. A sample of 99 of the brightest infrared starburst galaxies was settled on for the X-ray survey. For a set of practical size, this was then reduced to a subset of 53, based on luminosity and nearness. X-ray emission from these objects was individually measured from the UCSD HEAO-1 all-sky survey in four energy bands between 13 keV to 160 keV. This data base consists of about 20 optical disk volumes. Net significance for the result was roughly two sigma, and a very hard spectral shape is indicated for the net spectrum of the surveyed galaxies. With the possibility of detection of the class, it was then felt worthwhile to examine fluxes from these sources in other archival data. This was performed with the HEAO-1 A2 data and the HEAO-2 (EINSTEIN) main archive and slew survey. Positive results were also obtained for the sample, but again at weak significance. With three independent measures of weak X-ray fluxes from nearby starburst galaxies, we wrote a letter to the Astrophysical Journal (enclosed) discussing these results and their likely significance, in particular, for the contribution to the cosmic diffuse x-ray background, perhaps as much as 25 percent.

  3. Characterizing the radio continuum emission from intense starburst galaxies

    Galvin, T. J.; Seymour, N.; Filipović, M. D.; Tothill, N. F. H.; Marvil, J.; Drouart, G.; Symeonidis, M.; Huynh, M. T.

    2016-09-01

    The intrinsic thermal (free-free) and non-thermal (synchrotron) emission components that comprise the radio continuum of galaxies represent unique, dust-free measures of star formation rates (SFR). Such high SFR galaxies will dominate the deepest current and future radio surveys. We disentangle the thermal and non-thermal emission components of the radio continuum of six ultraluminous infrared galaxies (LFIR > 1012.5 L⊙) at redshifts of 0.2 ≤ z ≤ 0.5 and 22 IR selected galaxies. Radio data over a wide frequency range (0.8 < ν < 10 GHz) are fitted with a star-forming galaxy model comprising of thermal and non-thermal components. The luminosities of both radio continuum components are strongly correlated to the 60 μm luminosity across many orders of magnitude (consistent with the far-IR to radio correlation). We demonstrate that the spectral index of the radio continuum spectral energy distribution is a useful proxy for the thermal fraction. We also find that there is an increase in mean and scatter of the thermal fraction with FIR to radio luminosity ratio which could be influenced by different time-scales of the thermal and non-thermal emission mechanisms.

  4. The evolution of post-starburst galaxies from z=2 to z= 0.5

    Wild, Vivienne; Dunlop, Jim; Simpson, Chris; Rowlands, Kate; Bowler, Rebecca; Maltby, David; McLure, Ross

    2016-01-01

    We present the evolution in the number density and stellar mass functions of photometrically selected post-starburst galaxies in the UKIDSS Deep Survey (UDS), with redshifts of 0.510. We find that this transitionary species of galaxy is rare at all redshifts, contributing ~5% of the total population at z~2, to 2 they are exclusively massive galaxies that have formed the bulk of their stars during a rapid assembly period, followed by complete quenching of further star formation, (2) at z<1 they are caused by the rapid quenching of gas-rich star-forming galaxies, independent of stellar mass, possibly due to environment and/or gas-rich major mergers.

  5. Chemical Pollution and Evolution of Massive Starbursts: Cleaning up the Environment in Star-Forming Galaxies

    Kobulnicky, C.

    1996-12-01

    I present the results of a research program seeking to characterize the impact of massive star-clusters on the chemical and dynamical evolution of metal-poor, irregular and blue compact galaxies. The evolution of high mass stars is thought to contribute the bulk of heavy element enrichment in the interstellar medium, especially alpha -process elements like O, Si, etc. Yet, in actively star-forming galaxies, localized chemical inhomogeneities are seldom observed. Spatially-resolved optical and ultraviolet spectroscopy from the Hubble Space Telescope and ground-based observatories is used to search for chemical enrichment in the vicinity of young star clusters in nearby galaxies. VLA aperture synthesis maps are used to examine the neutral hydrogen content, dynamics, and local environment of the sample galaxies. Despite the spread in evolutionary state of the starbursts determined by the EW of Balmer emission lines and the radio continuum spectral index, few instances of localized enrichment are found. In light of these data, the ``instantaneous enrichment'' scenario for extragalactic HII regions appears less probable than one which operates on long timescales and global spatial scales. The results are consistent with the idea that starburst driven winds expel freshly synthesized metals in a hot 10(6) K phase into the halos of galaxies where they cool, condense into globules, and mix homogeneously with the rest of the galaxy on long (dynamical) timescales. The C/O and N/O ratios of the galaxies are used as new tools for measuring the recent star formation history. Implications for chemical evolution of galaxies both locally and cosmologically are developed.

  6. An excess of dusty starbursts related to the Spiderweb galaxy

    Dannerbauer, H; De Breuck, C; Wylezalek, D; Santos, J S; Koyama, Y; Seymour, N; Tanaka, M; Hatch, N; Altieri, B; Coia, D; Galametz, A; Kodama, T; Miley, G; Röttgering, H; Sanchez-Portal, M; Valtchanov, I; Venemans, B; Ziegler, B

    2014-01-01

    We present APEX LABOCA 870 micron observations of the field around the high-redshift radio galaxy MRC1138-262 at z=2.16. We detect 16 submillimeter galaxies in this ~140 square arcmin bolometer map with flux densities in the range 3-11 mJy. The raw number counts indicate a density of submillimeter galaxies (SMGs) that is up to four times that of blank field surveys. Based on an exquisite multiwavelength database, including VLA 1.4 GHz radio and infrared observations, we investigate whether these sources are members of the protocluster structure at z=2.2. Using Herschel PACS+SPIRE and Spitzer MIPS photometry, we derive reliable far-infrared photometric redshifts for all sources. Follow-up VLT ISAAC and SINFONI near-infrared spectra confirm that four of these SMGs have redshifts of z=2.2. We also present evidence that another SMG in this field, detected earlier at 850 micron, has a counterpart that exhibits Halpha and CO(1-0) emission at z=2.15. Including the radio galaxy and two SMGs with far-IR photometric re...

  7. Galaxy Zoo: building the low-mass end of the red sequence with local post-starburst galaxies

    Wong, O. I.; Schawinski, K.; Kaviraj, S.; Masters, K. L.; Nichol, R. C.; Lintott, C.; Keel, W. C.; Darg, D.; Bamford, S. P.; Andreescu, D.; Murray, P.; Raddick, M. J.; Szalay, A.; Thomas, D.; Vandenberg, J.

    2012-02-01

    We present a study of local post-starburst galaxies (PSGs) using the photometric and spectroscopic observations from the Sloan Digital Sky Survey and the results from the Galaxy Zoo project. We find that the majority of our local PSG population have neither early- nor late-type morphologies but occupy a well-defined space within the colour-stellar mass diagram, most notably, the low-mass end of the 'green valley' below the transition mass thought to be the mass division between low-mass star-forming galaxies and high-mass passively evolving bulge-dominated galaxies. Our analysis suggests that it is likely that local PSGs will quickly transform into 'red', low-mass early-type galaxies as the stellar morphologies of the 'green' PSGs largely resemble that of the early-type galaxies within the same mass range. We propose that the current population of PSGs represents a population of galaxies which is rapidly transitioning between the star-forming and the passively evolving phases. Subsequently, these PSGs will contribute towards the build-up of the low-mass end of the 'red sequence' once the current population of young stars fade and stars are no longer being formed. These results are consistent with the idea of 'downsizing' where the build-up of smaller galaxies occurs at later epochs. This publication has been made possible by the participation of more than 250 000 volunteers in the Galaxy Zoo project. Their contributions are individually acknowledged at .

  8. Evolution of the high-mass end of the stellar initial mass functions in starburst galaxies

    Bekki, Kenji

    2013-01-01

    We investigate the time evolution and spatial variation of the stellar initial mass function (IMF) in star-forming disk galaxies by using chemodynamical simulations with an IMF model depending both on local densities and metallicities ([Fe/H]) of the interstellar medium (ISM). We find that the slope (alpha) of a power-law IMF (N(m) ~ m^-alpha) for stellar masses larger than 1M_sun evolves from the canonical Salpeter IMF (alpha ~ 2.35) to be moderately top-heavy one (alpha ~ 1.9) in the simulated disk galaxies with starbursts triggered by galaxy interaction. We also find that alpha in star-forming regions correlates with star formation rate densities (Sigma_SFR in units of M_sun yr^{-1} kpc^{-2}). Feedback effects of Type Ia and II supernovae are found to prevent IMFs from being too top-heavy (alpha -2 (i.e., more top-heavy in higher Sigma_SFR), which is reasonably consistent well with corresponding recent observational results. The present study also predicts that inner regions of starburst disk galaxies hav...

  9. Seyfert 2 galaxies in the GeV band: jets and starburst

    Lenain, Jean-Philippe; Türler, Marc; Dorner, Daniela; Walter, Roland

    2010-01-01

    (Abridged) The Fermi/LAT collaboration recently reported the detection of starburt galaxies in the high energy gamma-ray domain, as well as radio-loud narrow-line Seyfert 1 objects. Motivated by the presence of sources close to the location of composite starburst/Seyfert 2 galaxies in the first year Fermi/LAT catalogue, we aim at studying high energy gamma-ray emission from such objects, and at disentangling the processes from starburst and active galactic nucleus activity. We analysed 1.6 years of Fermi/LAT data from NGC 1068 and NGC 4945, which count among the brightest Seyfert 2 galaxies. We search for potential variability of the high energy signal, and derive a spectrum of these sources. We also analyse public INTEGRAL IBIS/ISGRI data over the last seven years to derive their hard X-ray spectrum. We find an excess of high energy gamma-rays of 8.3 sigma and 9.2 sigma for 1FGL J0242.7+0007 and 1FGL J1305.4-4928, which are found to be consistent with the position of the Seyfert 2 galaxies NGC 1068 and NGC 4...

  10. An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10.

    Reines, Amy E; Sivakoff, Gregory R; Johnson, Kelsey E; Brogan, Crystal L

    2011-02-01

    Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first 'seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize 2-10 (refs 5 and 6) contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize 2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneously hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize 2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids. PMID:21217688

  11. Building the low-mass end of the red sequence with local post-starburst galaxies

    Wong, O. Ivy; Schawinski, K.; Kaviraj, S.; Masters, K.; Nichol, R.; Lintott, C.; Keel, W.; Darg, D.; Bamford, S.; Galaxy Zoo Team

    2011-05-01

    We present a study of local post-starburst galaxies (PSG) using the photometric and spectroscopic observations from the Sloan Digital Sky Survey (SDSS) and the results from the Galaxy Zoo project. We find that 74% of the local PSG are of indeterminate morphology. These local PSG also occupy a well-defined space within the color-stellar mass diagram, most notably in the low-mass end of the green valley below the transition mass described by Kauffmann et al. to be the mass division between low-mass star-forming galaxies and high-mass passively-evolving bulge-dominated galaxies. Our analysis suggests that it is likely that a local PSG will quickly transform into low-mass early-type galaxies as the stellar morphologies of the green PSG largely resemble that of the early-type galaxies within the same mass range. We propose that the current populations of PSG represent one population of galaxies which are rapidly transitioning from the blue cloud to the red sequence and subsequently, contributing towards the build-up of the low-mass end of the red sequence. This finding is consistent with the idea of downsizing where the build-up of smaller galaxies occurs at later epochs.

  12. Detailed Analysis of Starburst and AGN Activity in Blue E/S0 Galaxies in RESOLVE

    Bittner, Ashley; Snyder, Elaine M.; Kannappan, Sheila; Norman, Dara J.; Norris, Mark A.; Moffett, Amanda J.; Hoversten, Erik A.; Stark, David; RESOLVE Team

    2016-01-01

    We identify a population of ~120 blue E/S0 galaxies among the ~1350 galaxies that are targeted for spectroscopy and have measured morphologies in the highly complete REsolved Spectroscopy Of a Local Volume (RESOLVE) survey. Blue E/S0s are identified as being early type objects morphologically classified between E and S0/a that fall on the blue sequence. Most (~85%) of our blue E/S0s have stellar masses sample. Using three variations of the M_BH -- sigma relation, this kinematic subsample is estimated to typically host central black holes within the range log M_BH = 4-6 M_sun. Following up on previous suggestions of nuclear activity in the blue E/S0 population, we investigate nuclear starburst and/or AGN activity occurring within the full sample. Preliminary results from cross-checking known AGN catalogs with the blue E/S0 sample have revealed nuclear activity in ~20 of these galaxies based on heterogeneous criteria (BPT line ratio analysis, spectral line broadening, etc.), some of which may not entirely distinguish starburst from AGN activity. In an attempt to break the degeneracy between AGN and starburst activity, we perform detailed spectral analysis for a few of the galaxies with kinematic data. We also consider the viability of alternate AGN detection methods based on L_Edd estimates calculated from the M_BH estimates. This research has been supported by the National Science Foundation through the CAP REU Program (ACI-1156614) and the RESOLVE Survey (AST-0955368) as well as the National Space Grant College and Fellowship Program and the NC Space Grant Consortium.

  13. Interpreting the low-frequency radio spectra of starburst galaxies: a pudding of Strömgren spheres

    Lacki, Brian C.

    2013-06-01

    The low-frequency radio emission of starburst galaxies is informative, but it can be absorbed in several ways. Most importantly, starburst galaxies are home to many H II regions, whose free-free absorption blocks low-frequency radio waves. These H II regions are discrete objects, but most multiwavelength models of starbursts assume a uniform medium of ionized gas, if they include the absorption at all. I calculate the effective absorption coefficient of H II regions in starbursts, which is ultimately a cross-section times the density of H II regions. The cross-sections are calculated by assuming that H II regions are Strömgren spheres. The coefficient asymptotes to a constant value at low frequencies, because H II regions partially cover the starburst and are buried part way into the starburst's synchrotron-emitting material. Considering Strömgren spheres around either OB stars or Super Star Clusters, I demonstrate the method by fitting to the low-frequency radio spectrum of M82. I discuss implications of the results for synchrotron spectrum shape, H II region pressure and free-free emission as a star formation rate indicator. However, these results are preliminary and could be affected by systematics. I argue that there is no volume-filling warm ionized medium in starbursts and that H II regions may be the most important absorption process down to ˜10 MHz. Future data at low and high radio frequency will improve our knowledge of the ionized gas.

  14. Suppression of star formation in the galaxy NGC 253 by a starburst-driven molecular wind.

    Bolatto, Alberto D; Warren, Steven R; Leroy, Adam K; Walter, Fabian; Veilleux, Sylvain; Ostriker, Eve C; Ott, Jürgen; Zwaan, Martin; Fisher, David B; Weiss, Axel; Rosolowsky, Erik; Hodge, Jacqueline

    2013-07-25

    The under-abundance of very massive galaxies in the Universe is frequently attributed to the effect of galactic winds. Although ionized galactic winds are readily observable, most of the expelled mass (that is, the total mass flowing out from the nuclear region) is likely to be in atomic and molecular phases that are cooler than the ionized phases. Expanding molecular shells observed in starburst systems such as NGC 253 (ref. 12) and M 82 (refs 13, 14) may facilitate the entrainment of molecular gas in the wind. Although shell properties are well constrained, determining the amount of outflowing gas emerging from such shells and the connection between this gas and the ionized wind requires spatial resolution better than 100 parsecs coupled with sensitivity to a wide range of spatial scales, a combination hitherto not available. Here we report observations of NGC 253, a nearby starburst galaxy (distance ∼ 3.4 megaparsecs) known to possess a wind, that trace the cool molecular wind at 50-parsec resolution. At this resolution, the extraplanar molecular gas closely tracks the Hα filaments, and it appears to be connected to expanding molecular shells located in the starburst region. These observations allow us to determine that the molecular outflow rate is greater than 3 solar masses per year and probably about 9 solar masses per year. This implies a ratio of mass-outflow rate to star-formation rate of at least 1, and probably ∼3, indicating that the starburst-driven wind limits the star-formation activity and the final stellar content. PMID:23887428

  15. Galaxy Zoo: building the low-mass end of the red sequence with local post-starburst galaxies

    Wong, O Ivy; Kaviraj, S; Masters, K L; Nichol, R C; Lintott, C; Keel, W C; Darg, D; Bamford, S P; Andreescu, D; Murray, P; Raddick, M J; Szalay, A; Thomas, D; VandenBerg, J

    2011-01-01

    We present a study of local post-starburst galaxies (PSGs) using the photometric and spectroscopic observations from the Sloan Digital Sky Survey (SDSS) and the results from the Galaxy Zoo project. We find that the majority of our local PSG population have neither early- nor late- type morphologies but occupy a well-defined space within the colour-stellar mass diagram, most notably, the low-mass end of the "green valley" below the transition mass thought to be the mass division between low-mass star-forming galaxies and high-mass passively-evolving bulge-dominated galaxies. Our analysis suggests that it is likely that a local PSG will quickly transform into "red", low-mass early-type galaxies as the stellar morphologies of the "green" PSGs largely resemble that of the early-type galaxies within the same mass range. We propose that the current population of PSGs represents a population of galaxies which is rapidly transitioning between the star-forming and the passively-evolving phases. Subsequently, these PSG...

  16. EVOLUTION OF THE HIGH-MASS END OF THE STELLAR INITIAL MASS FUNCTIONS IN STARBURST GALAXIES

    Bekki, Kenji; Meurer, Gerhardt R. [ICRAR, M468, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)

    2013-03-01

    We investigate the time evolution and spatial variation of the stellar initial mass function (IMF) in star-forming disk galaxies by using chemodynamical simulations with an IMF model depending both on local densities and metallicities ([Fe/H]) of the interstellar medium (ISM). We find that the slope ({alpha}) of a power-law IMF (N(m){proportional_to}m {sup -{alpha}}) for stellar masses larger than 1 M{sub Sun} evolves from the canonical Salpeter IMF ({alpha} Almost-Equal-To 2.35) to be moderately top-heavy one ({alpha} Almost-Equal-To 1.9) in the simulated disk galaxies with starbursts triggered by galaxy interaction. We also find that {alpha} in star-forming regions correlates with star formation rate densities ({Sigma}{sub SFR} in units of M{sub Sun} yr{sup -1} kpc{sup -2}). Feedback effects of Type Ia and II supernovae are found to prevent IMFs from being too top-heavy ({alpha} < 1.5). The simulation predicts {alpha} Almost-Equal-To 0.23log {Sigma}{sub SFR} + 1.7 for log {Sigma}{sub SFR} {>=} -2 (i.e., more top-heavy in higher {Sigma}{sub SFR}), which is reasonably consistent with corresponding recent observational results. The present study also predicts that inner regions of starburst disk galaxies have smaller {alpha} and thus are more top-heavy (d{alpha}/dR {approx} 0.07 kpc{sup -1} for R {<=} 5 kpc). The predicted radial {alpha} gradient can be tested against future observational studies of the {alpha} variation in star-forming galaxies.

  17. Clumpy and Extended Starbursts in the Brightest Unlensed Submillimeter Galaxies

    Iono, Daisuke; Aretxaga, Itziar; Hatsukade, Bunyo; Hughes, David; Ikarashi, Soh; Izumi, Takuma; Kawabe, Ryohei; Kohno, Kotaro; Lee, Minju; Matsuda, Yuichi; Nakanishi, Kouichiro; Saito, Toshiki; Tamura, Yoichi; Ueda, Junko; Umehata, Hideki; Wilson, Grant; Michiyama, Tomonari; Ando, Misaki

    2016-01-01

    The central structure in three of the brightest unlensed z=3-4 submillimeter galaxies are investigated through 0.015" - 0.05" (120 -- 360~pc) 860 micron continuum images obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). The distribution in the central kpc in AzTEC1 and AzTEC8 are extremely complex, and they are composed of multiple ~200 pc clumps. AzTEC4 consists of two sources that are separated by ~1.5 kpc, indicating a mid-stage merger. The peak star formation rate densities in the central clumps are ~300 - 3000 Msun/yr/kpc^2, suggesting regions with extreme star formation near the Eddington Limit. By comparing the flux obtained by ALMA and Submillimeter Array (SMA), we find that 68-90% of the emission is extended (> 1 kpc) in AzTEC 4 and 8. For AzTEC1, we identify at least 11 additional compact (~200 pc) clumps in the extended 3 - 4 kpc region. Overall, the data presented here suggest that the luminosity surface densities observed at 1 kpc regions, some of which could also be clumpy...

  18. The identification of post-starburst galaxies at z ˜ 1 using multiwavelength photometry: a spectroscopic verification

    Maltby, David T.; Almaini, Omar; Wild, Vivienne; Hatch, Nina A.; Hartley, William G.; Simpson, Chris; McLure, Ross J.; Dunlop, James; Rowlands, Kate; Cirasuolo, Michele

    2016-06-01

    Despite decades of study, we still do not fully understand why some massive galaxies abruptly switch off their star formation in the early Universe, and what causes their rapid transition to the red sequence. Post-starburst galaxies provide a rare opportunity to study this transition phase, but few have currently been spectroscopically identified at high redshift (z > 1). In this paper, we present the spectroscopic verification of a new photometric technique to identify post-starbursts in high-redshift surveys. The method classifies the broad-band optical-near-infrared spectral energy distributions (SEDs) of galaxies using three spectral shape parameters (supercolours), derived from a principal component analysis of model SEDs. When applied to the multiwavelength photometric data in the UKIDSS Ultra Deep Survey, this technique identified over 900 candidate post-starbursts at redshifts 0.5 5 Å) and Balmer break, characteristic of post-starburst galaxies. We conclude that photometric methods can be used to select large samples of recently-quenched galaxies in the distant Universe.

  19. The Discovery of Spiral Arms in the Starburst Galaxy M82

    Mayya, Y D; Luna, A

    2005-01-01

    We report the discovery of two symmetric spiral arms in the near-infrared (NIR) images of the starburst galaxy M82. The spiral arms are recovered when an axi-symmetric exponential disk is subtracted from the NIR images. The arms emerge from the ends of the NIR bar and can be traced up to three disk scalelengths. The winding of the arms is consistent with an m=2 logarithmic spiral mode of pitch angle 14 degrees. The arms are bluer than the disk in spite of their detection on the NIR images. If the northern side of the galaxy is nearer to us, as is normally assumed, the observed sense of rotation implies trailing arms. The nearly edge-on orientation, high disk surface brightness, and the presence of a complex network of dusty filaments in the optical images, are responsible for the lack of detection of the arms in previous studies.

  20. Chandra Observations of Expanding Shells in the Dwarf Starburst Galaxy NGC 3077

    Ott, J; Walter, F; Ott, Juergen; Martin, Crystal L.; Walter, Fabian

    2003-01-01

    Deep Chandra observations (53 ks, ACIS-S3) of NGC 3077, a starburst dwarf galaxy in the M 81 triplet, resolve the X-ray emission from several supershells. The emission is brightest in the cavities defined by expanding shells detected previously in H alpha emission (Martin 1998). Thermal emission models fitted to the data imply temperatures ranging from ~1.3 to 4.9 x 10^(6) K and indicate that the strongest absorption is coincident with the densest clouds traced by CO emission. The fitted emission measures give pressures of P/k~10^(5-6) xi^(-0.5) f_(v)^(-0.5) K cm^(-3) (xi: metallicity of the hot gas in solar units, f_(v): volume filling factor). Despite these high pressures, the radial density profile of the hot gas is not as steep as that expected in a freely expanding wind (e.g., as seen in the neighboring starburst galaxy M 82) implying that the hot gas is still confined by the H alpha shells. The chaotic dynamical state of NGC 3077 undermines reliable estimates of the escape velocity. The more relevant qu...

  1. Star cluster versus field star formation in the nucleus of the prototype starburst galaxy M82

    Barker, S; Cerviño, M

    2008-01-01

    We analyse high-resolution Hubble Space Telescope/Advanced Camera for Surveys imaging of the nuclear starburst region of M82, obtained as part of the Hubble Heritage mosaic made of this galaxy, in four filters (Johnson-Cousins equivalent B, V, and I broad bands, and an Halpha narrow-band filter), as well as subsequently acquired U-band images. We find a complex system of ~150 star clusters in the inner few 100 pc of the galaxy. We do not find any conclusive evidence of a cluster-formation epoch associated with the most recent starburst event, believed to have occurred about 4-6 Myr ago. This apparent evidence of decoupling between cluster and field-star formation is consistent with the view that star cluster formation requires special conditions. However, we strongly caution, and provide compelling evidence, that the `standard' simple stellar population analysis method we have used significantly underestimates the true uncertainties in the derived ages due to stochasticity in the stellar initial mass function...

  2. Localized Starbursts in Dwarf Galaxies Produced by the Impact of Low-metallicity Cosmic Gas Clouds

    Sánchez Almeida, J.; Elmegreen, B. G.; Muñoz-Tuñón, C.; Elmegreen, D. M.; Pérez-Montero, E.; Amorín, R.; Filho, M. E.; Ascasibar, Y.; Papaderos, P.; Vílchez, J. M.

    2015-09-01

    Models of galaxy formation predict that gas accretion from the cosmic web is a primary driver of star formation over cosmic history. Except in very dense environments where galaxy mergers are also important, model galaxies feed from cold streams of gas from the web that penetrate their dark matter halos. Although these predictions are unambiguous, the observational support has been indirect so far. Here, we report spectroscopic evidence for this process in extremely metal-poor galaxies (XMPs) of the local universe, taking the form of localized starbursts associated with gas having low metallicity. Detailed abundance analyses based on Gran Telescopio Canarias optical spectra of 10 XMPs show that the galaxy hosts have metallicities around 60% solar, on average, while the large star-forming regions that dominate their integrated light have low metallicities of some 6% solar. Because gas mixes azimuthally in a rotation timescale (a few hundred Myr), the observed metallicity inhomogeneities are only possible if the metal-poor gas fell onto the disk recently. We analyze several possibilities for the origin of the metal-poor gas, favoring the metal-poor gas infall predicted by numerical models. If this interpretation is correct, XMPs trace the cosmic web gas in their surroundings, making them probes to examine its properties.

  3. From H I to Stars: H I Depletion in Starbursts and Star-forming Galaxies in the ALFALFA Hα Survey

    Jaskot, A. E.; Oey, M. S.; Salzer, J. J.; Van Sistine, A.; Bell, E. F.; Haynes, M. P.

    2015-07-01

    H i in galaxies traces the fuel for future star formation and reveals the effects of feedback on neutral gas. Using a statistically uniform, H i-selected sample of 565 galaxies from the Arecibo Legacy Fast ALFA (ALFALFA) Hα survey, we explore H i properties as a function of star formation activity. ALFALFA Hα provides R-band and Hα imaging for a volume-limited subset of the 21 cm ALFALFA survey. We identify eight starbursts based on Hα equivalent width and six with enhanced star formation relative to the main sequence. Both starbursts and non-starbursts have similar H i-to-stellar mass ratios ({M}{{H} {{I}}}/{M}*), which suggests that feedback is not depleting the starbursts’ H i. Consequently, the starbursts do have shorter H i depletion times ({t}{dep}), implying more efficient H i-to-H2 conversion. While major mergers likely drive this enhanced efficiency in some starbursts, the lowest-mass starbursts may experience periodic bursts, consistent with enhanced scatter in {t}{dep} at low {M}*. Two starbursts appear to be pre-coalescence mergers; their elevated {M}{{H} {{I}}}/{M}* suggest that H i-to-H2 conversion is still ongoing at this stage. By comparing with the GASS sample, we find that {t}{dep} anticorrelates with stellar surface density for disks, while spheroids show no such trend. Among early-type galaxies, {t}{dep} does not correlate with bulge-to-disk ratio; instead, the gas distribution may determine the star formation efficiency. Finally, the weak connection between galaxies’ specific star formation rates and {M}{{H} {{I}}}/{M}* contrasts with the well-known correlation between {M}{{H} {{I}}}/{M}* and color. We show that dust extinction can explain the H i–color trend, which may arise from the relationship between {M}*, {M}{{H} {{I}}}, and metallicity.

  4. The Far-Infrared Energy Distributions of Seyfert and Starburst Galaxies in the Local Universe: Infrared Space Observatory Photometry of the 12 Micron Active Galaxy Sample

    Spinoglio, Luigi; Andreani, Paola; Malkan, Matthew A.

    2002-06-01

    New far-infrared photometry with ISOPHOT aboard the Infrared Space Observatory (ISO) is presented for 58 galaxies with homogeneous published data for another 32 galaxies, all belonging to the 12 μm galaxy sample-in total, 29 Seyfert 1 galaxies, 35 Seyfert 2 galaxies, and 12 starburst galaxies, or about half of the 12 μm active galaxy sample, plus 14 normal galaxies for comparison. ISO and Infrared Astronomical Satellite (IRAS) data are used to define color-color diagrams and spectral energy distributions (SEDs). Thermal dust emission at two temperatures (one cold at 15-30 K and one warm at 50-70 K) can fit the 60-200 μm SED, with a dust emissivity law proportional to the inverse square of the wavelength. Seyfert 1 galaxies and Seyfert 2 galaxies are indistinguishable longward of 100 μm, while, as already seen by IRAS, the former have flatter SEDs shortward of 60 μm. A mild anticorrelation is found between the [200-100] color and the ``60 μm excess.'' We infer that this is due to the fact that galaxies with a strong starburst component and thus a strong 60 μm flux have a steeper far-infrared turnover. In non-Seyfert galaxies, increasing the luminosity corresponds to increasing the star formation rate, which enhances the 25 and 60 μm emission. This shifts the peak emission from around 150 μm in the most quiescent spirals to shorter than 60 μm in the strongest starburst galaxies. To quantify these trends further, we identified with the IRAS colors three idealized infrared SEDs: pure quiescent disk emission, pure starburst emission, and pure Seyfert nucleus emission. Even between 100 and 200 μm, the quiescent disk emission remains much cooler than the starburst component. Seyfert galaxies have 100-200 μm SEDs ranging from pure disks to pure starbursts, with no apparent contribution from their active nuclei at those wavelengths. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France

  5. Starburst galaxies in the COSMOS field: clumpy star-formation at redshift 0 < z < 0.5

    Hinojosa-Goñi, R.; Muñoz-Tuñón, C.; Méndez-Abreu, J.

    2016-08-01

    Context. At high redshift, starburst galaxies present irregular morphologies with 10-20% of their star formation occurring in giant clumps. These clumpy galaxies are considered the progenitors of local disk galaxies. To understand the properties of starbursts at intermediate and low redshift, it is fundamental to track their evolution and the possible link with the systems at higher z. Aims: We present an extensive, systematic, and multiband search and analysis of the starburst galaxies at redshift (0 1010. We classify galaxies into three main types, depending on their HST morphology: single knot (Sknot), single star-forming knot plus diffuse light (Sknot+diffuse), and multiple star-forming knots (Mknots/clumpy) galaxy. We found a fraction of Mknots/clumpy galaxy fclumpy = 0.24 considering out total sample of starburst galaxies up to z ~ 0.5. The individual star-forming knots in our sample follows the same L(Hα) vs. size scaling relation as local giant HII regions. However, they slightly differ from the one provided using samples at high redshift. This result highlights the importance of spatially resolving the star-forming regions for this kind of study. Star-forming clumps in the central regions of Mknots galaxies are more massive, and present higher star formation rates, than those in the outskirts. This trend is less clear when we consider either the mass surface density or surface star formation rate. Sknot galaxies do show properties similar to both dwarf elliptical and irregulars in the surface brightness (μ) versus Mhost diagram in the B-band, and to spheroidals and ellipticals in the μ versus Mhost diagram in the V-band. Conclusions: The properties of our star-forming knots in Sknot+diffuse and Mknots/clumpy galaxies support the predictions of recent numerical simulations claiming that they have been produced by violent disk instabilities. We suggest that the evolution of these knots means that large and massive clumps at the galaxy centers represent

  6. A Massive, Cooling-Flow-Induced Starburst in the Core of a Highly Luminous Galaxy Cluster

    McDonald, M; Benson, B A; Foley, R J; Ruel, J; Sullivan, P; Veilleux, S; Aird, K A; Ashby, M L N; Bautz, M; Bazin, G; Bleem, L E; Brodwin, M; Carlstrom, J E; Chang, C L; Cho, H M; Clocchiatti, A; Crawford, T M; Crites, A T; de Haan, T; Desai, S; Dobbs, M A; Dudley, J P; Egami, E; Forman, W R; Garmire, G P; George, E M; Gladders, M D; Gonzalez, A H; Halverson, N W; Harrington, N L; High, F W; Holder, G P; Holzapfel, W L; Hoover, S; Hrubes, J D; Jones, C; Joy, M; Keisler, R; Knox, L; Lee, A T; Leitch, E M; Lieu, J; Lueker, M; Luong-Van, D; Mantz, A; Marrone, D P; McMahon, J J; Mehl, J; Meyer, S S; Miller, E D; Mocanu, L; Mohr, J J; Montroy, T E; Murray, S S; Natoli, T; Padin, S; Plagge, T; Pryke, C; Rawle, T D; Reichardt, C L; Rest, A; Rex, M; Ruhl, J E; Saliwanchik, B R; Saro, A; Sayre, J T; Schaffer, K K; Shaw, L; Shirokoff, E; Simcoe, R; Song, J; Spieler, H G; Stalder, B; Staniszewski, Z; Stark, A A; Story, K; Stubbs, C W; Suhada, R; van Engelen, A; Vanderlinde, K; Vieira, J D; Vikhlinin, A; Williamson, R; Zahn, O; Zenteno, A

    2012-01-01

    In the cores of some galaxy clusters the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous "cooling flows" of gas sinking towards the cluster center, yet no such cooling flow has been observed. The low observed star formation rates and cool gas masses for these "cool core" clusters suggest that much of the cooling must be offset by astrophysical feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical, and infrared observations of the galaxy cluster SPT-CLJ2344-4243 at z = 0.596. These observations reveal an exceptionally luminous (L_2-10 keV = 8.2 x 10^45 erg/s) galaxy cluster which hosts an extremely strong cooling flow (dM/dt = 3820 +/- 530 Msun/yr). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (740 +/- 160 Msun/yr), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool core clusters may not yet be fully establishe...

  7. THE GREEN BANK TELESCOPE MAPS THE DENSE, STAR-FORMING GAS IN THE NEARBY STARBURST GALAXY M82

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO+. Here we demonstrate the power of the Robert C. Byrd Green Bank Telescope (GBT)—the largest single-dish millimeter radio telescope—for mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN and HCO+ in the starburst galaxy M82. The HCN and HCO+ in the disk of this galaxy correlates with both recent star formation and more diffuse molecular gas and shows kinematics consistent with a rotating torus. The HCO+ emission extending to the north and south of the disk is coincident with the outflow previously identified in CO and traces the eastern edge of the hot outflowing gas. The central starburst region has a higher ratio of star formation to dense gas than the outer regions, pointing to the starburst as a key driver of this relationship. These results establish that the GBT can efficiently map the dense molecular gas at 90 GHz in nearby galaxies, a capability that will increase further with the 16 element feed array under construction

  8. Physical properties and evolutionary state of the Lyman alpha emitting starburst galaxy IRAS 08339+6517

    Oti-Floranes, H; Jimenez-Bailon, E; Schaerer, D; Hayes, M; Ostlin, G; Atek, H; Kunth, D

    2014-01-01

    Though Lyman alpha emission (Lya) is one of the most used tracers of massive star formation at high redshift, a correct understanding of radiation transfer effects by neutral gas is required to properly quantify the star formation rate along the history of the Universe. We are embarked in a program to study the properties of the Lya emission (spectral profile, spatial distribution, relation to Balmer lines intensity,...) in several local starburst galaxies. We present here the results obtained for IRAS 08339+6517. Using evolutionary population synthesis models, we have characterized the properties of the starburst (UV continuum, Halpha, total infrared and X-ray emissions, etc.), which transformed 1.4e+8 Mo of gas into stars around 5-6 Myr ago. In addition to the central compact emission blob, we have identified a diffuse Lya emission component smoothly distributed over the whole central area of IRAS 08339+6517. This diffuse emission is spatially decoupled from the UV continuum, the Halpha emission or the Halp...

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

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

    2015-01-01

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

  10. Extinction, profile asymmetry, and tidal effects in Seyfert and starburst galaxies

    Dahari, O.; De robertis, M.M.

    1988-08-01

    Possible correlations between luminosity, extinction, and morphological properties of 246 Seyfert and starburst galaxies are investigated. It is shown that the asymmetry of the forbidden O III 5007 A profile is correlated with the signature of dust in both Seyfert types, and therefore establishes a direct connection between them. A positive correlation is found between soft X-ray luminosities and optical reddening for Seyfert 2's and a negative correlation for Seyfert 1's. These and other correlations are discussed in the context of current models of active nuclei. No statistically significant differences are found between Seyferts with and without companions, except that interacting Seyfert 2's have excess infrared and radio-continuum emission. 58 references.

  11. Extinction, profile asymmetry, and tidal effects in Seyfert and starburst galaxies

    Dahari, Oved; De Robertis, Michael M.

    1988-01-01

    Possible correlations between luminosity, extinction, and morphological properties of 246 Seyfert and starburst galaxies are investigated. It is shown that the asymmetry of the forbidden O III 5007 A profile is correlated with the signature of dust in both Seyfert types, and therefore establishes a direct connection between them. A positive correlation is found between soft X-ray luminosities and optical reddening for Seyfert 2's and a negative correlation for Seyfert 1's. These and other correlations are discussed in the context of current models of active nuclei. No statistically significant differences are found between Seyferts with and without companions, except that interacting Seyfert 2's have excess infrared and radio-continuum emission.

  12. Extinction, profile asymmetry, and tidal effects in Seyfert and starburst galaxies

    Possible correlations between luminosity, extinction, and morphological properties of 246 Seyfert and starburst galaxies are investigated. It is shown that the asymmetry of the forbidden O III 5007 A profile is correlated with the signature of dust in both Seyfert types, and therefore establishes a direct connection between them. A positive correlation is found between soft X-ray luminosities and optical reddening for Seyfert 2's and a negative correlation for Seyfert 1's. These and other correlations are discussed in the context of current models of active nuclei. No statistically significant differences are found between Seyferts with and without companions, except that interacting Seyfert 2's have excess infrared and radio-continuum emission. 58 references

  13. Probing the Circumnuclear Stellar Populations of Starburst Galaxies in the Near-infrared

    Dametto, N Z; Pastoriza, M G; Rodríguez-Ardila, A; Hernandez-Jimenez, J A; Carvalho, E A

    2014-01-01

    We employ the NASA Infrared Telescope Facility's near-infrared spectrograph SpeX at 0.8-2.4$\\mu$m to investigate the spatial distribution of the stellar populations (SPs) in four well known Starburst galaxies: NGC34, NGC1614, NGC3310 and NGC7714. We use the STARLIGHT code updated with the synthetic simple stellar populations models computed by Maraston (2005, M05). Our main results are that the NIR light in the nuclear surroundings of the galaxies is dominated by young/intermediate age SPs ($t \\leq 2\\times10^9$yr), summing from $\\sim$40\\% up to 100\\% of the light contribution. In the nuclear aperture of two sources (NGC1614 and NGC3310) we detected a predominant old SP component ($t > 2\\times10^9$yr), while for NGC34 and NGC7714 the younger component prevails. Furthermore, we found evidence of a circumnuclear star formation ring-like structure and a secondary nucleus in NGC1614, in agreement with previous studies. We also suggest that the merger/interaction experienced by three of the galaxies studied, NGC161...

  14. Compact starbursts in z~3-6 submillimeter galaxies revealed by ALMA

    Ikarashi, Soh; Caputi, Karina I; Aretxaga, Itziar; Dunlop, James S; Hatsukade, Bunyo; Hughes, DavidH; Iono, Daisuke; Izumi, Takuma; Kawabe, Ryohei; Kohno, Kotaro; Lagos, ClaudiaD P; Motohara, Kentaro; Nakanishi, Koichiro; Ohta, Kouji; Tamura, Yoichi; Umehata, Hideki; Wilson, GrantG; Yabe, Kiyoto; Yun, Min S

    2014-01-01

    We report the source size distribution, as measured by ALMA millimetric continuum imaging, of a sample of 13 AzTEC-selected submillimeter galaxies (SMGs) believed to lie at z_photo ~ 3-6. Their infrared luminosities and star-formation rates (SFR) are L_IR ~ 2-6 x 10^12 L_sun and ~ 200-500 M_sun yr-1, respectively. The size of z ~ 3-6 SMGs ranges from 0''.10 to 0''.38 with a median of 0''.22 (FWHM), corresponding to a median effective radius (Re) of ~ 0.8 kpc, comparable to the typical size of the stellar component measured in compact quiescent galaxies at z ~ 2 (cQGs) --- R ~ 1 kpc. The surface SFR density of our z ~ 3-6 SMGs is 160+610-82 M_sun yr-1 kpc-2, comparable to that seen in local merger-driven (U)LIRGs, which implies that these SMGs are also likely to be merger-driven. The discovery of compact starbursts in z >~ 3 SMGs strongly supports a massive galaxy formation scenario wherein z ~ 3-6 SMGs evolve into the compact stellar components of z ~ 2 cQGs. These cQGs are then thought to evolve into the mos...

  15. Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph

    Leitherer, Claus; Lee, Janice C; Oey, M S

    2016-01-01

    We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232 and Mrk 54 were observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescopes. The three galaxies have radial velocities of ~13,000 km/s, permitting a ~35 A window on the restframe Lyman continuum shortward of the Milky Way Lyman edge at 912 A. The chosen instrument configuration using the G140L grating covers the spectral range from 912 to 2,000 {\\AA}. We developed a dedicated background subtraction method to account for temporal and spatial background variations of the detector, which is crucial at the low flux levels around 912 A. This modified pipeline allowed us to significantly improve the statistical and systematic detector noise and will be made available to the community. We detect Lyman continuum in all three galaxies. However, we conservatively interpret the emission in Tol 0440-381 as an upper limit due to possible contamination by geocoronal Lyman series lines. ...

  16. Warm Dust and Spatially Variable PAH Emission in the Dwarf Starburst Galaxy NGC 1705

    Cannon, J M; Bendo, G J; Buckalew, B A; Calzetti, D; Dale, D A; Draine, B T; Engelbracht, C W; Gordon, K D; Helou, G; Hollenbach, D J; Jarrett, T H; Kennicutt, R C; Leitherer, C; Li, A; Meyer, M J; Murphy, E J; Regan, M W; Rieke, G H; Rieke, M J; Roussel, H; Sheth, K; Smith, J D T; Thornley, M D; Walter, F; Armus, Lee; Bendo, George J.; Buckalew, Brent A.; Calzetti, Daniela; Cannon, John M.; Dale, Daniel A.; Draine, Bruce T.; Engelbracht, Charles W.; Gordon, Karl D.; Helou, George; Hollenbach, David J.; Jarrett, Thomas H.; Kennicutt, Robert C.; Leitherer, Claus; Li, Aigen; Meyer, Martin J.; Murphy, Eric J.; Regan, Michael W.; Rieke, George H.; Rieke, Marcia J.; Roussel, Helene; Sheth, Kartik; Smith, John-David T.; Thornley, Michele D.; Walter, Fabian

    2006-01-01

    We present Spitzer observations of the dwarf starburst galaxy NGC 1705 obtained as part of SINGS. The galaxy morphology is very different shortward and longward of ~5 microns: short-wavelength imaging shows an underlying red stellar population, with the central super star cluster (SSC) dominating the luminosity; longer-wavelength data reveals warm dust emission arising from two off-nuclear regions offset by ~250 pc from the SSC. These regions show little extinction at optical wavelengths. The galaxy has a relatively low global dust mass (~2E5 solar masses, implying a global dust-to-gas mass ratio ~2--4 times lower than the Milky Way average). The off-nuclear dust emission appears to be powered by photons from the same stellar population responsible for the excitation of the observed H Alpha emission; these photons are unassociated with the SSC (though a contribution from embedded sources to the IR luminosity of the off-nuclear regions cannot be ruled out). Low-resolution IRS spectroscopy shows moderate-streng...

  17. Starburst galaxies in the COSMOS field: clumpy star-formation at redshift 0 < z < 0.5

    Hinojosa-Goñi, R; Méndez-Abreu, J

    2016-01-01

    At high redshift, starburst galaxies present irregular morphologies, with 10-20\\%\\ of their star formation occurring in giant clumps. These clumpy galaxies are considered to be the progenitors of local disk galaxies. To understand the properties of starbursts at intermediate and low redshift, it is fundamental to track their evolution and possible link with the systems at higher $z$. We present an extensive, systematic, and multi-band search and analysis of the starburst galaxies at redshift ($0 < z < 0.5$) in the COSMOS field, as well as detailed characteristics of their star-forming clumps by using Hubble Space Telescope/Advance Camera for Surveys (HST/ACS) images. Their principal properties, sizes, masses, and star formation rates are provided. The individual star-forming knots in our sample follow the same L(H$\\alpha$) vs. size scaling relation than local giant HII regions (Fuentes-Masip et al. 2000). However, they slightly differ from the one provided using samples at high redshift. This result hig...

  18. An enhanced fraction of starbursting galaxies among high Eddington ratio AGNs

    Bernhard, E.; Mullaney, J. R.; Daddi, E.; Ciesla, L.; Schreiber, C.

    2016-07-01

    We investigate the star-forming properties of 1620 X-ray selected active galactic nuclei (AGN) host galaxies as a function of their specific X-ray luminosity (i.e. X-ray luminosity per unit host stellar mass) - a proxy of the Eddington ratio. Our motivation is to determine whether there is any evidence of a suppression of star formation at high Eddington ratios, which may hint towards `AGN feedback' effects. Star formation rates (SFRs) are derived from fits to Herschel-measured far-infrared spectral energy distributions, taking into account any contamination from the AGN. Herschel-undetected AGNs are included via stacking analyses to provide average SFRs in bins of redshift and specific X-ray luminosity (spanning 0.01 ≲ L_X/M_{ast } ≲ 100 L_{{⊙}} M_{{⊙}}^{-1}). After normalizing for the effects of mass and redshift arising from the evolving galaxy main sequence, we find that the SFRs of high specific luminosity AGNs are slightly enhanced compared to their lower specific luminosity counterparts. This suggests that the SFR distribution of AGN hosts changes with specific X-ray luminosity, a result reinforced by our finding of a significantly higher fraction of starbursting hosts among high specific luminosity AGNs compared to that of the general star-forming galaxy population (i.e. 8-10 per cent versus 3 per cent). Contrary to our original motivation, our findings suggest that high specific luminosity AGNs are more likely to reside in galaxies with enhanced levels of star formation.

  19. An enhanced fraction of starbursting galaxies among high Eddington ratio AGNs

    Bernhard, E.; Mullaney, J. R.; Daddi, E.; Ciesla, L.; Schreiber, C.

    2016-04-01

    We investigate the star-forming properties of 1620 X-ray selected AGN host galaxies as a function of their specific X-ray luminosity (i.e., X-ray luminosity per unit host stellar mass) - a proxy of the Eddington ratio. Our motivation is to determine whether there is any evidence of a suppression of star-formation at high Eddington ratios, which may hint toward "AGN feedback" effects. Star-formation rates (SFRs) are derived from fits to Herschel-measured far-infrared spectral energy distributions, taking into account any contamination from the AGN. Herschel-undetected AGNs are included via stacking analyses to provide average SFRs in bins of redshift and specific X-ray luminosity (spanning 0.01 ≲ L_X/M_{ast } ≲ 100 L_{⊙} M_{⊙}^{-1}). After normalising for the effects of mass and redshift arising from the evolving galaxy main sequence, we find that the SFRs of high specific luminosity AGNs are slightly enhanced compared to their lower specific luminosity counterparts. This suggests that the SFR distribution of AGN hosts changes with specific X-ray luminosity, a result reinforced by our finding of a significantly higher fraction of starbursting hosts among high specific luminosity AGNs compared to that of the general star-forming galaxy population (i.e., 8-10 per cent vs. 3 per cent). Contrary to our original motivation, our findings suggest that high specific luminosity AGNs are more likely to reside in galaxies with enhanced levels of star-formation.

  20. Formaldehyde Densitometry of Starburst Galaxies: Density-Independent Global Star Formation

    Mangum, Jeffrey G; Henkel, Christian; Menten, Karl M

    2013-01-01

    Accurate techniques which allow for the derivation of the spatial density in star formation regions are rare. A technique which has found application for the derivation of spatial densities in Galactic star formation regions utilizes the density-sensitive properties of the K-doublet transitions of formaldehyde (H2CO). In this paper, we present an extension of our survey of the formaldehyde 1(10)-1(11) (lambda = 6.2 cm) and 2(11)-2(12) (lambda = 2.1 cm) K-doublet transitions of H2CO in a sample of 56 starburst systems (Mangum etal. 2008). We have extended the number of galaxies in which both transitions have been detected from 5 to 13. We have improved our spatial density measurements by incorporating kinetic temperatures based upon NH3 measurements of 11 of the galaxies with a total of 14 velocity components in our sample (Mangum etal. 2013). Our spatial density measurements lie in a relatively narrow range of from 10^(4.5) to 10^(5.5) cm^(-3). This implies that the Schmidt-Kennicutt relation between L_(IR) a...

  1. Evidence for an Interaction in the Nearest Starbursting Dwarf Irregular Galaxy IC 10

    Nidever, David L; Slater, Colin T; Ott, Juergen; Johnson, Megan; Bell, Eric F; Stanimirovic, Snezana; Putman, Mary; Majewski, Steven R; Simpson, Caroline E; Juette, Eva; Oosterloo, Tom A; Burton, W Butler

    2013-01-01

    Using deep 21-cm HI data from the Green Bank Telescope we have detected an ~18.3 kpc-long gaseous extension associated with the starbursting dwarf galaxy IC 10. The newly-found feature stretches 1.3 deg to the northwest and has a large radial velocity gradient reaching to ~65 km/s lower than the IC 10 systemic velocity. A region of higher column density at the end of the extension that possesses a coherent velocity gradient (~10 km/s across ~26 arcmin) transverse to the extension suggests rotation and may be a satellite galaxy of IC 10. The HI mass of IC 10 is 9.5x10^7 (d/805 kpc)^2 Msun and the mass of the new extension is 7.1x10^5 (d/805 kpc)^2 Msun. An IC 10-M31 orbit using known radial velocity and proper motion values for IC 10 show that the HI extension is inconsistent with the trailing portion of the orbit so that an M31-tidal or ram pressure origin seems unlikely. We argue that the most plausible explanation for the new feature is that it is the result of a recent interaction (and possible late merger...

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

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

    2014-01-01

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

  3. Gas Dynamics and Outflow in the Barred Starburst Galaxy NGC 1808 Revealed with ALMA

    Salak, Dragan; Hatakeyama, Takuya; Miyamoto, Yusuke

    2016-01-01

    NGC 1808 is a nearby barred starburst galaxy with an outflow from the nuclear region. To study the inflow and outflow processes related to star formation and dynamical evolution of the galaxy, we have carried out \\(^{12}\\)CO (\\(J=1-0\\)) mapping observations of the central \\(r\\sim4\\) kpc of NGC 1808 using the Atacama Large Millimeter/submillimeter Array (ALMA). Four distinct components of molecular gas are revealed at high spatial resolution of 2\\arcsec (\\(\\sim100\\) pc): (1) a compact (\\(r<200\\) pc) circumnuclear disk (CND), (2) \\(r\\sim500\\) pc ring, (3) gas-rich galactic bar, and (4) spiral arms. Basic geometric and kinematic parameters are derived for the central 1-kpc region using tilted-ring modeling. The derived rotation curve reveals multiple mass components that include (1) a stellar bulge, (2) nuclear bar and molecular CND, and (3) unresolved massive (\\(\\sim10^7~M_\\sun\\)) core. Two systemic velocities, 998 km s\\(^{-1}\\) for the CND and 964 km s\\(^{-1}\\) for the 500-pc ring, are revealed, indicating ...

  4. The magnetized galactic wind and synchrotron halo of the starburst dwarf galaxy IC10

    Chyzy, Krzysztof T; Beck, Rainer; Urbanik, Marek; Heesen, Volker; Bomans, Dominik J

    2016-01-01

    We aim to explore whether strong magnetic fields can be effectively generated in low-mass dwarf galaxies and, if so, whether such fields can be affected by galactic outflows and spread out into the intergalactic medium (IGM). We performed a radio continuum polarimetry study of IC10, the nearest starbursting dwarf galaxy, using a combination of multifrequency interferometric (VLA) and single-dish (Effelsberg) observations. VLA observations at 1.43 GHz reveal an extensive and almost spherical radio halo of IC10 in total intensity, extending twice more than the infrared-emitting galactic disk. The halo is magnetized with a magnetic field strength of 7 microG in the outermost parts. Locally, the magnetic field reaches about 29 microG in HII complexes, becomes more ordered, and weakens to 22 microG in the synchrotron superbubble and to 7-10 microG within HI holes. At the higher frequency of 4.86 GHz, we found a large-scale magnetic field structure of X-shaped morphology, similar to that observed in several edge-on...

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

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

    2016-01-01

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

  6. Constraints on the presence of water megamaser emission in z~2.5 ultraluminous infrared starburst galaxies

    Wagg, Jeff

    2009-01-01

    We present Expanded Very Large Array and Arecibo observations of two lensed submm galaxies at z~2.5, in order to search for redshifted 22.235 GHz water megamaser emission. Both SMM J14011+0252 and SMM J16359+6612 have multi-wavelength characteristics consistent with ongoing starburst activity, as well as CO line emission indicating the presence of warm molecular gas. Our observations do not reveal any evidence for H2O megamaser emission in either target, while the lensing allows us to obtain deep limits to the H_2O line luminosities, L(H2O) < 7470 Lsun (3-sigma) in the case of SMM J14011+0252, and L(H2O) < 1893 Lsun for SMM J16359+6612, assuming linewidths of 80 km/s. Our search for, and subsequent non-detection of H2O megamaser emission in two strongly lensed starburst galaxies, rich in gas and dust, suggests that such megamaser emission is not likely to be common within the unlensed population of high-redshift starburst galaxies. We use the recent detection of strong H2O megamaser emission in the lens...

  7. Chandra & XMM-Newton Observations of NGC5253. Analysis of the X-ray Emission from a Dwarf Starburst Galaxy

    Summers, L K; Strickland, D K; Heckman, T M; Summers, Lesley K.; Stevens, Ian R.; Strickland, David K.; Heckman, Timothy M.

    2004-01-01

    We present Chandra and XMM-Newton X-ray data of NGC5253, a local starbursting dwarf elliptical galaxy, in the early stages of a starburst episode. Contributions to the X-ray emission come from discrete point sources and extended diffuse emission, in the form of what appear to be multiple superbubbles, and smaller bubbles probably associated with individual star clusters. Chandra detects 17 sources within the optical extent of NGC5253 down to a completeness level corresponding to a luminosity of 1.5E37 erg/s.The slope of the point source X-ray luminosity function is -0.54, similar to that of other nearby dwarf starburst galaxies. Several different types of source are detected within the galaxy, including X-ray binaries and the emission associated with star-clusters. Comparison of the diffuse X-ray emission with the observed Halpha emission shows similarities in their extent. The best spectral fit to the diffuse emission is obtained with an absorbed, two temperature model giving temperatures for the two gas com...

  8. THE GREEN BANK TELESCOPE MAPS THE DENSE, STAR-FORMING GAS IN THE NEARBY STARBURST GALAXY M82

    Kepley, Amanda A.; Frayer, David [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944-0002 (United States); Leroy, Adam K. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Usero, Antonio [Observatorio Astronómico Nacional, C/Alfonso XII, 3, E-28014 Madrid (Spain); Marvil, Josh [Department of Physics, New Mexico Tech., 801 Leroy Place, Socorro, NM 87801 (United States); Walter, Fabian, E-mail: akepley@nrao.edu [Max Planck Institute fur Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

    2014-01-01

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO{sup +}. Here we demonstrate the power of the Robert C. Byrd Green Bank Telescope (GBT)—the largest single-dish millimeter radio telescope—for mapping dense gas in galaxies by presenting the most sensitive maps yet of HCN and HCO{sup +} in the starburst galaxy M82. The HCN and HCO{sup +} in the disk of this galaxy correlates with both recent star formation and more diffuse molecular gas and shows kinematics consistent with a rotating torus. The HCO{sup +} emission extending to the north and south of the disk is coincident with the outflow previously identified in CO and traces the eastern edge of the hot outflowing gas. The central starburst region has a higher ratio of star formation to dense gas than the outer regions, pointing to the starburst as a key driver of this relationship. These results establish that the GBT can efficiently map the dense molecular gas at 90 GHz in nearby galaxies, a capability that will increase further with the 16 element feed array under construction.

  9. A 2 mm spectral line survey of the starburst galaxy NGC 253

    Martín, S; Henkel, C; Martín-Pintado, J; Mauersberger, R

    2006-01-01

    We present the first unbiased molecular line survey towards an extragalactic source, namely the nuclear region of the starburst galaxy NGC 253. The scan covers the frequency band from 129.1 to 175.2 GHz, i.e. most of the 2mm atmospheric window. We identify 111 spectral features as transitions from 25 different molecular species. Eight of which (three tentatively) are detected for the first time in the extragalactic interstellar medium. Among these newly detected species, we detected the rare isotopomers 34SO and HC18O+. Tentative detections of two deuterated species, DNC and N2D+, are reported for the first time from a target beyond the Magellanic Clouds. Additionally, three hydrogen recombination lines are identified, while no organic molecules larger than methanol are detected. Column densities and rotation temperatures are calculated for all the species, including an upper limit to the ethanol abundance. A comparison of the chemical composition of the nuclear environment of NGC 253 with those of selected n...

  10. X-ray Detections of Sub-millimetre Galaxies: Active Galactic Nuclei Versus Starburst Contribution

    Johnson, Seth P; Wang, Danial Q; Williams, Christina C; Scott, Kim S; Yun, Min S; Pope, Alexandra; Lowenthal, James; Aretxaga, Itziar; Hughes, David; Kim, M J; Kim, Sungeun; Tamura, Yoichi; Kohno, Kotaro; Ezawa, Hajime; Kawabe, Ryohei; Oshima, Tai; 10.1093/mnras/stt197

    2013-01-01

    We present a large-scale study of the X-ray properties and near-IR-to-radio SEDs of submillimetre galaxies (SMGs) detected at 1.1mm with the AzTEC instrument across a ~1.2 square degree area of the sky. Combining deep 2-4 Ms Chandra data with Spitzer IRAC/MIPS and VLA data within the GOODS-N/S and COSMOS fields, we find evidence for AGN activity in ~14 percent of 271 AzTEC SMGs, ~28 percent considering only the two GOODS fields. Through X-ray spectral modeling and SED fitting using Monte Carlo Markov Chain techniques to Siebenmorgen et al. (2004) (AGN) and Efstathiou et al. (2000) (starburst) templates, we find that while star formation dominates the IR emission, with SFRs ~100-1000 M_sun/yr, the X-ray emission for most sources is almost exclusively from obscured AGNs, with column densities in excess of 10^23 cm^-2. Only for ~6 percent of our sources do we find an X-ray-derived SFR consistent with NIR-to-radio SED derived SFRs. Inclusion of the X-ray luminosities as a prior to the NIR-to-radio SED effectively...

  11. Gas Dynamics and Outflow in the Barred Starburst Galaxy NGC 1808 Revealed with ALMA

    Salak, Dragan; Nakai, Naomasa; Hatakeyama, Takuya; Miyamoto, Yusuke

    2016-05-01

    NGC 1808 is a nearby barred starburst galaxy with an outflow from the nuclear region. To study the inflow and outflow processes related to star formation and dynamical evolution of the galaxy, we have carried out 12CO (J=1-0) mapping observations of the central r ∼ 4 kpc of NGC 1808 using the Atacama Large Millimeter/submillimeter Array. Four distinct components of molecular gas are revealed at high spatial resolution of 2″ (∼100 pc): (1) a compact (r < 200 pc) circumnuclear disk (CND), (2) r ∼ 500 pc ring, (3) gas-rich galactic bar, and (4) spiral arms. Basic geometric and kinematic parameters are derived for the central 1 kpc region using tilted-ring modeling. The derived rotation curve reveals multiple mass components that include (1) a stellar bulge, (2) a nuclear bar and molecular CND, and (3) an unresolved massive (∼107 M ⊙) core. Two systemic velocities, 998 km s‑1 for the CND and 964 km s‑1 for the 500 pc ring, are revealed, indicating a kinematic offset. The pattern speed of the primary bar, derived by using a cloud-orbit model, is 56 ± 11 km s‑1 kpc‑1. Noncircular motions are detected associated with a nuclear spiral pattern and outflow in the central 1 kpc region. The ratio of the mass outflow rate to the star formation rate is {\\dot{M}}{out}/{SFR}∼ 0.2 in the case of optically thin CO (1–0) emission in the outflow, suggesting low efficiency of star formation quenching.

  12. RELATIONSHIP BETWEEN STAR FORMATION RATE AND BLACK HOLE ACCRETION AT z = 2: THE DIFFERENT CONTRIBUTIONS IN QUIESCENT, NORMAL, AND STARBURST GALAXIES

    We investigate the co-evolution of the black hole accretion rate (BHAR) and the star formation rate (SFR) in 1.5galaxies displaying a greater diversity of star-forming properties compared to previous studies. We combine X-ray stacking and far-IR photometry of stellar mass-limited samples of normal star-forming, starburst, and quiescent/quenched galaxies in the COSMOS field. We corroborate the existence of a strong correlation between BHAR (i.e., the X-ray luminosity, LX) and stellar mass (M*) for normal star-forming galaxies, though we find a steeper relation than previously reported. We find that starbursts show a factor of three enhancement in BHAR compared to normal SF galaxies (against a factor of six excess in SFR), while quiescents show a deficit of a factor times 5.5 at a given mass. One possible interpretation of this is that the starburst phase does not coincide with cosmologically relevant BH growth, or that starburst-inducing mergers are more efficient at boosting SFR than BHAR. Contrary to studies based on smaller samples, we find that the BHAR/SFR ratio of main-sequence (MS) galaxies is not mass invariant, but scales weakly as M∗0.43±0.09, implying faster BH growth in more massive galaxies at z∼2. Furthermore, BHAR/SFR during the starburst is a factor of two lower than in MS galaxies, at odds with the predictions of hydrodynamical simulations of merger galaxies that foresee a sudden enhancement of LX/SFR during the merger. Finally, we estimate that the bulk of the accretion density of the universe at z∼2 is associated with normal star-forming systems, with only ∼6(±1)% and ∼11(±1)% associated with starburst and quiescent galaxies, respectively

  13. Relationship between star formation rate and black hole accretion at z=3: the different contributions in quiescent, normal, and starburst galaxies

    Rodighiero, G.; Franceschini, A.; Baronchelli, I. [Dipartimento di Fisica e Astronomia “G. Galilei”, Universita’ di Padova, Vicolo dell’Osservatorio 3, I-35122 (Italy); Brusa, M.; Delvecchio, I.; Pozzi, F.; Cimatti, A. [Dipartimento di Fisica e Astronomia, Università di Bologna, viale Berti Pichat 6/2, I-40127 Bologna (Italy); Daddi, E.; Strazzullo, V. [Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/Service d’Astrophysique, Bât.709, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex (France); Negrello, M.; Renzini, A. [INAF-Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 2, I-35122 Padova (Italy); Mullaney, J. R. [Department of Physics and Astronomy, University of Sheffield, S3 7RH (United Kingdom); Lutz, D. [Max Planck Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany); Gruppioni, C. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127, Bologna (Italy); Silverman, J., E-mail: giulia.rodighiero@unipd.it [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo, Kashiwanoha, Kashiwa 277-8583 (Japan)

    2015-02-10

    We investigate the co-evolution of the black hole accretion rate (BHAR) and the star formation rate (SFR) in 1.5galaxies displaying a greater diversity of star-forming properties compared to previous studies. We combine X-ray stacking and far-IR photometry of stellar mass-limited samples of normal star-forming, starburst, and quiescent/quenched galaxies in the COSMOS field. We corroborate the existence of a strong correlation between BHAR (i.e., the X-ray luminosity, L{sub X}) and stellar mass (M{sub *}) for normal star-forming galaxies, though we find a steeper relation than previously reported. We find that starbursts show a factor of three enhancement in BHAR compared to normal SF galaxies (against a factor of six excess in SFR), while quiescents show a deficit of a factor times 5.5 at a given mass. One possible interpretation of this is that the starburst phase does not coincide with cosmologically relevant BH growth, or that starburst-inducing mergers are more efficient at boosting SFR than BHAR. Contrary to studies based on smaller samples, we find that the BHAR/SFR ratio of main-sequence (MS) galaxies is not mass invariant, but scales weakly as M{sub ∗}{sup 0.43±0.09}, implying faster BH growth in more massive galaxies at z∼2. Furthermore, BHAR/SFR during the starburst is a factor of two lower than in MS galaxies, at odds with the predictions of hydrodynamical simulations of merger galaxies that foresee a sudden enhancement of L{sub X}/SFR during the merger. Finally, we estimate that the bulk of the accretion density of the universe at z∼2 is associated with normal star-forming systems, with only ∼6(±1)% and ∼11(±1)% associated with starburst and quiescent galaxies, respectively.

  14. High-Resolution Near-Infrared Spectroscopy of an Equivalent Width-Selected Sample of Starbursting Dwarf Galaxies

    Maseda, Michael V.; VanDerWeL, Arjen; DaChuna, Elisabete; Rix, Hans-Walter; Pacafichi, Camilla; Momcheva, Ivelina; Brammer, Gabriel B.; Franx, Marijn; VanDokkum, Pieter; Bell, Eric F.; Ferguson, Harry C.; Fumagalli, Mattia; Grogin, Norman A.; Kocevski, Dale D.; Koekemoer, Anton M.; Lundgren, Britt F.; Marchesini, Danilo; Nelson, Erica J.; Patel, Shannon; Skelton, Rosalind E.; Straughn, Amber N.; Trump, Jonathan R.; Weiner, Benjamin J.; Whitaker, Katherine E.; Wuyts, Stijn

    2013-01-01

    Spectroscopic observations from the Large Binocular Telescope and the Very Large Telescope reveal kinematically narrow lines (approx. 50 km/s) for a sample of 14 Extreme Emission Line Galaxies (EELGs) at redshifts 1.4 < zeta < 2.3. These measurements imply that the total dynamical masses of these systems are low ( 3 × 10(exp 9) M). Their large [O III]5007 equivalent widths (500 - 1100 A) and faint blue continuum emission imply young ages of 10-100 Myr and stellar masses of 10(exp 8)-10(exp 9) M, confirming the presence of a violent starburst. The stellar mass formed in this vigorous starburst phase thus represents a large fraction of the total (dynamical) mass, without a significantly massive underlying population of older stars. The occurrence of such intense events in shallow potentials strongly suggests that supernova-driven winds must be of critical importance in the subsequent evolution of these systems.

  15. Star Dust Formation Activities in AzTEC-3: A Starburst Galaxy at z=5.3

    Dwek, Eliahu

    2011-01-01

    Analyses of of high-redshift ultraluminous infrared OR) galaxies traditionally use the observed optical to submillimeter spectral energy distribution (SED) and estimates of the dynamical mass as observational constraints to derive the star formation rate (SFR), the stellar mass, and age of these objects. In this lecture we add this constraint to the analysis of AzTEC-3, a starburst galaxy at z=5.3. We construct different stellar and chemical evolutionary scenarios, constrained to produce the inferred dust mass and observed luminosity before the associated stellar mass exceeds the observational limit. A robust result of our models is that all scenarios require most of the radiating dust mass to have been accreted in molecular clouds. Our new procedure highlights the importance of a multi wavelength approach, and of the use of dust evolution models in constraining the age and the star formation activity and history in galaxies.

  16. Star and Dust Formation Activities in AzTEC-3: A Starburst Galaxy at z=5.3

    Dwek, Eliahu

    2011-01-01

    Analyses of of high-redshift ultraluminous infrared (IR) galaxies traditionally use the observed optical to submillimeter spectral energy distribution (SED) and estimates of the dynamical mass as observational constraints to derive the star formation rate (SFR), the stellar mass, and age of these objects. In this lecture we add this constraint to the analysis of AzTEC-3, a starburst galaxy at z=5.3. We construct different stellar and chemical evolutionary scenarios, constrained to produce the inferred dust mass and observed luminosity before the associated stellar mass exceeds the observational limit. A robust result of our models is that all scenarios require most of the radiating dust mass to have been accreted in molecular clouds. Our new procedure highlights the importance of a multiwavelength approach, and of the use of dust evolution models in constraining the age and the star formation activity and history in galaxies.

  17. Star and Dust Formation Activities in AzTEC-3: A Starburst Galaxy at z equals 5.3

    Dwek, Eliahu

    2011-01-01

    Analyses of of high-redshift ultraluminous infrared (IR) galaxies traditionally use the observed optical to submillimeter spectral energy distribution (SED) and estimates of the dynamical mass as observational constraints to derive the star formation rate (SFR), the stellar mass, and age of these objects. In this lecture we add this constraint to the analysis of AzTEC-3, a starburst galaxy at z=5.3. We construct different stellar and chemical evolutionary scenarios, constrained to produce the inferred dust mass and observed luminosity before the associated stellar mass exceeds the observational limit. A robust result of our models is that all scenarios require most of the radiating dust mass to have been accreted in molecular clouds. Our new procedure highlights the importance of a multi wavelength approach, and of the use of dust evolution models in constraining the age and the star formation activity and history in galaxies.

  18. 3D-HST GRISM SPECTROSCOPY OF A GRAVITATIONALLY LENSED, LOW-METALLICITY STARBURST GALAXY AT z = 1.847

    We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z = 1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extremely strong [O III] λ5007 and Hβ emission lines with rest-frame equivalent widths of 2000 ± 100 and 520 ± 40 Å, respectively. The source has a stellar mass ∼108 M☉, sSFR ∼ 100 Gyr–1, and detection of [O III] λ4363 yields a metallicity of 12 + log (O/H) = 7.5 ± 0.2. We identify local blue compact dwarf analogs to SL2SJ02176-0513, which are among the most metal-poor galaxies in the Sloan Digital Sky Survey. The local analogs resemble the lensed galaxy in many ways, including UV/optical spectral energy distribution, spatial morphology, and emission line equivalent widths and ratios. Common to SL2SJ02176-0513 and its local counterparts is an upturn at mid-IR wavelengths likely arising from hot dust heated by starbursts. The emission lines of SL2SJ02176-0513 are spatially resolved owing to the combination of the lens and the high spatial resolution of HST. The lensed galaxy is composed of two clumps with combined size re ∼300 pc, and we resolve significant differences in UV color and emission line equivalent width between them. Though it has characteristics occasionally attributed to active galactic nuclei, we conclude that SL2SJ02176-0513 is a low-metallicity star-bursting dwarf galaxy. Such galaxies will be found in significant numbers in the full 3D-HST grism survey.

  19. 3D-HST GRISM SPECTROSCOPY OF A GRAVITATIONALLY LENSED, LOW-METALLICITY STARBURST GALAXY AT z = 1.847

    Brammer, Gabriel B.; Sanchez-Janssen, Ruben [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago (Chile); Labbe, Ivo; Franx, Marijn; Fumagalli, Mattia; Patel, Shannon [Leiden Observatory, Leiden University, 2300-RA Leiden (Netherlands); Da Cunha, Elisabete; Rix, Hans-Walter; Schmidt, Kasper B.; Van der Wel, Arjen [Max Planck Institute for Astronomy (MPIA), Koenigstuhl 17, D-69117 Heidelberg (Germany); Erb, Dawn K. [Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States); Lundgren, Britt; Momcheva, Ivelina; Nelson, Erica; Skelton, Rosalind E.; Van Dokkum, Pieter G.; Wake, David A.; Whitaker, Katherine E. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Marchesini, Danilo [Physics and Astronomy Department, Tufts University, Robinson Hall, Room 257, Medford, MA 02155 (United States); Quadri, Ryan, E-mail: gbrammer@eso.org [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2012-10-10

    We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z = 1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extremely strong [O III] {lambda}5007 and H{beta} emission lines with rest-frame equivalent widths of 2000 {+-} 100 and 520 {+-} 40 A, respectively. The source has a stellar mass {approx}10{sup 8} M{sub Sun }, sSFR {approx} 100 Gyr{sup -1}, and detection of [O III] {lambda}4363 yields a metallicity of 12 + log (O/H) = 7.5 {+-} 0.2. We identify local blue compact dwarf analogs to SL2SJ02176-0513, which are among the most metal-poor galaxies in the Sloan Digital Sky Survey. The local analogs resemble the lensed galaxy in many ways, including UV/optical spectral energy distribution, spatial morphology, and emission line equivalent widths and ratios. Common to SL2SJ02176-0513 and its local counterparts is an upturn at mid-IR wavelengths likely arising from hot dust heated by starbursts. The emission lines of SL2SJ02176-0513 are spatially resolved owing to the combination of the lens and the high spatial resolution of HST. The lensed galaxy is composed of two clumps with combined size r{sub e} {approx}300 pc, and we resolve significant differences in UV color and emission line equivalent width between them. Though it has characteristics occasionally attributed to active galactic nuclei, we conclude that SL2SJ02176-0513 is a low-metallicity star-bursting dwarf galaxy. Such galaxies will be found in significant numbers in the full 3D-HST grism survey.

  20. Spectral analysis and interpretation of the \\gamma-ray emission from the Starburst galaxy NGC 253

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Balzer, A; Barnacka, A; Becherini, Y; Becker, J; Bernlöhr, K; Birsin, E; Biteau, J; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Cologna, G; Conrad, J; Couturier, C; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Fegan, S; Feinstein, F; Fernandes, M V; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Gast, H; Gérard, L; Giebels, B; Glicenstein, J F; Glück, B; Göring, D; Grondin, M -H; Häffner, S; Hague, J D; Hahn, J; Hampf, D; Harris, J; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Krayzel, F; Laffon, H; Lamanna, G; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Mohamed, M; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Wilhelmi, E de Oña; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sheidaei, F; Skilton, J L; Sol, H; Spengler, G; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; White, R; Wierzcholska, A; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S

    2012-01-01

    Very-high-energy (VHE; E >100 GeV) and high-energy (HE; 100 MeV < E < 100 GeV) data from \\gamma-ray observations performed with the H.E.S.S. telescope array and the Fermi-LAT instrument, respectively, are analysed in order to investigate the non-thermal processes in the starburst galaxy NGC 253. The VHE \\gamma-ray data can be described by a power law in energy with differential photon index \\Gamma=2.14 \\pm 0.18_stat \\pm 0.30_sys and differential flux normalisation at 1 TeV of F_0 = (9.6 \\pm 1.5_stat (+5.7,-2.9)_sys) x 10^{-14} TeV^{-1} cm^{-2} s^{-1}. A power-law fit to the differential HE \\gamma-ray spectrum reveals a photon index of \\Gamma=2.24 \\pm 0.14_stat \\pm 0.03_sys and an integral flux between 200 MeV and 200 GeV of F(0.2-200 GeV) = (4.9 \\pm 1.0_stat \\pm 0.3_sys) x 10^{-9} cm^{-2} s^{-1}. No evidence for a spectral break or turnover is found over the dynamic range of both the LAT instrument and the H.E.S.S. experiment: a combined fit of a power law to the HE and VHE \\gamma-ray data results in a ...

  1. CALIFA Spectroscopy of the Interacting Galaxy NGC 5394 (Arp 84): Starbursts, Enhanced [NII]6584 and Signs of Outflows and Shocks

    Roche, Nathan; Gomes, Jean Michel; Papaderos, Polychronis; Lagos, Patricio; Sanchez, Sebastian F

    2015-01-01

    We investigate the spiral galaxy NGC 5394, which is strongly interacting with the larger spiral NGC 5395 (the pair is Arp 84), using optical integral-field spectroscopy from the CALIFA survey. Spatially-resolved equivalent-widths, emission-line ratios and kinematics reveal many features related to the interaction, which has reshaped the galaxy. $\\rm H\\alpha$ maps (with other diagnostic emission lines) show a concentrated central ($r<1$ kpc) starburst and three less luminous star-forming regions (one knot far out in the northern arm), and we estimate the dust-corrected total star-formation rate as 3.39 $\\rm M_{\\odot}yr^{-1}$. However, much of the galaxy, especially the outer tidal arms, has a post-starburst spectrum, evidence of a more extensive episode of star-formation a few $\\times 10^8$ yr ago, triggered by the previous perigalacticon. The $\\rm [NII]6584/H\\alpha$ ratio is high in the nucleus, reaching 0.63 at the centre, which we interpret as related to high electron density ($n_e\\simeq 750$ $\\rm cm^{-3...

  2. Starbursting brightest cluster galaxy: a Herschel view of the massive cluster MACS J1931.8-2634

    Santos, J. S.; Balestra, I.; Tozzi, P.; Altieri, B.; Valtchanov, I.; Mercurio, A.; Nonino, M.; Yu, Heng; Rosati, P.; Grillo, C.; Medezinski, E.; Biviano, A.

    2016-02-01

    We investigate the dust-obscured star formation (SF) properties of the massive, X-ray-selected galaxy cluster MACS J1931.8-2634 at z = 0.352. Using far-infrared (FIR) imaging in the range 100-500 μm obtained with the Herschel telescope, we extract 31 sources (2σ) within r ˜ 1 Mpc from the brightest cluster galaxy (BCG). Among these sources, we identify six cluster members for which we perform an analysis of their spectral energy distributions (SEDs). We measure total infrared luminosity (LIR), star formation rate (SFR) and dust temperature. The BCG, with LIR = 1.4 × 1012 L⊙ is an ultraluminous infrared galaxy and hosts a type-II active galactic nuclei (AGN). We decompose its FIR SED into AGN and starburst components and find equal contributions from AGN and starburst. We also recompute the SFR of the BCG finding SFR = 150 ± 15 M⊙ yr-1. We search for an isobaric cooling flow in the cool core using Chandra X-ray data, and find no evidence for gas colder than 1.8 keV in the inner 30 kpc, for an upper limit to the instantaneous mass-deposition rate of 58 M⊙ yr-1 at 95 per cent c.l. This value is 3× lower than the SFR in the BCG, suggesting that the on-going SF episode lasts longer than the intracluster medium cooling events.

  3. Starbursting Brightest Cluster Galaxy: a Herschel view of the massive cluster MACS J1931.8-2634

    Santos, J S; Tozzi, P; Altieri, B; Valtchanov, I; Mercurio, A; Nonino, M; Yu, Heng; Rosati, P; Grillo, C; Medezinski, E; Biviano, A

    2015-01-01

    We investigate the dust-obscured star formation properties of the massive, X-ray selected galaxy cluster MACS J1931.8-2634 at $z$=0.352. Using far-infrared (FIR) imaging in the range 100-500$\\mu$m obtained with the \\textit{Herschel} telescope, we extract 31 sources (2$\\sigma$) within $r\\sim$1 Mpc from the brightest cluster galaxy (BCG). Among these sources we identify six cluster members for which we perform an analysis of their spectral energy distributions (SEDs). We measure total infrared luminosity (L$_{IR}$), star formation rate (SFR) and dust temperature. The BCG, with L$_{IR}$=1.4$\\times$10$^{12}$L$_\\odot$ is an Ultra Luminous Infrared Galaxy and hosts a type II AGN. We decompose its FIR SED into AGN and starburst components and find equal contributions from AGN and starburst. We also recompute the SFR of the BCG finding SFR=150$\\pm$15 M$_\\odot$yr$^{-1}$. We search for an isobaric cooling flow in the cool core using {\\sl Chandra} X-ray data, and find no evidence for gas colder than 1.8 keV in the inner...

  4. FORMATION OF DENSE MOLECULAR GAS AND STARS AT THE CIRCUMNUCLEAR STARBURST RING IN THE BARRED GALAXY NGC 7552

    We present millimeter molecular line complemented by optical observations, along with a reanalysis of archival centimeter H I and continuum data, to infer the global dynamics and determine where dense molecular gas and massive stars preferentially form in the circumnuclear starburst ring of the barred-spiral galaxy NGC 7552. We find diffuse molecular gas in a pair of dust lanes each running along the large-scale galactic bar, as well as in the circumnuclear starburst ring. We do not detect dense molecular gas in the dust lanes, but find such gas concentrated in two knots where the dust lanes make contact with the circumnuclear starburst ring. When convolved to the same angular resolution as the images in dense gas, the radio continuum emission of the circumnuclear starburst ring also exhibits two knots, each lying downstream of an adjacent knot in dense gas. The results agree qualitatively with the idea that massive stars form from dense gas at the contact points, where diffuse gas is channeled into the ring along the dust lanes, and later explode as supernovae downstream of the contact points. Based on the inferred rotation curve, however, the propagation time between the respective pairs of dense gas and centimeter continuum knots is about an order of magnitude shorter than the lifetimes of OB stars. We discuss possible reasons for this discrepancy, and conclude that either the initial mass function is top-heavy or massive stars in the ring do not form exclusively at the contact points where dense molecular gas is concentrated.

  5. THE ORIGIN OF [O II] IN POST-STARBURST AND RED-SEQUENCE GALAXIES IN HIGH-REDSHIFT CLUSTERS

    /Seyfert, we estimate that at least ∼20% of galaxies in high-redshift clusters with M*>1010-1010.5 Msun contain a LINER/Seyfert component that can be revealed with line ratios. We also investigate the effect such a population has on the global star formation rate of cluster galaxies and the post-starburst fraction, concluding that LINER/Seyferts must be accounted for if these quantities are to be physically meaningful.

  6. Distribution of Molecules in the Circumnuclear Disk and Surrounding Starburst Ring in the Seyfert Galaxy NGC 1068 Observed with ALMA

    Takano, S.; Nakajima, T.; Kohno, K.; Harada, N.; Herbst, E.; Tamura, Y.; Izumi, T.; Taniguchi, A.; Tosaki, T.

    2015-12-01

    We report distributions of several molecular transitions including shock and dust related species (13CO and C18O J = 1-0, 13CN N = 1-0, CS J = 2-1, SO JN = 32-21, HNCO JKa,Kc = 50,5-40,4, HC3N J = 11-10, 12-11, CH3OH JK = 2K-1K, and CH3CN JK = 6K-5K) in the nearby Seyfert 2 galaxy NGC 1068 observed with ALMA. The central ˜1' (˜4.3 kpc) of this galaxy was observed in the 100 GHz region with an angular resolution of ˜4" x 2" (290 pc x 140 pc) to study the effects of an active galactic nucleus and its surrounding starburst ring on molecular abundances. We report a classification of molecular distributions into three main categories. Organic molecules such as CH3CN are found to be concentrated in the circumnuclear disk. In the starburst ring, the intensity of methanol at each clumpy region is not consistent with that of 13CO.

  7. Exploring AGN - starburst coexistence in galaxies at z$\\sim$ 0.8 by the [OIII]4959+5007/[OIII]4363 line ratio

    Contini, M

    2016-01-01

    We analyze by detailed modelling the spectra observed from the sample galaxies at z$\\sim$0.8 presented by Ly et al (2015), constraining the models by the [OIII]5007+4959/[OIII]4363 line ratios. Composite models accounting for shock and photoionization by AGN or starburst are adopted. O/H are about solar for all the objects, except for a few AGN clouds with O/H= 0.3 -0.5 solar. Starburst models reproduce most of the data within the observational errors. About half of the object spectra are well fitted by an accreting AGN. Some galaxies show multiple radiation sources, such as starburst+AGN, or a double AGN.

  8. Discovery of a Galaxy Cluster with a Violently Starbursting Core at z = 2.506

    Wang, Tao; Elbaz, David; Daddi, Emanuele; Finoguenov, Alexis; Liu, Daizhong; Schreiber, Corentin; Martín, Sergio; Strazzullo, Veronica; Valentino, Francesco; van der Burg, Remco; Zanella, Anita; Ciesla, Laure; Gobat, Raphael; Le Brun, Amandine; Pannella, Maurilio; Sargent, Mark; Shu, Xinwen; Tan, Qinghua; Cappelluti, Nico; Li, Yanxia

    2016-09-01

    We report the discovery of a remarkable concentration of massive galaxies with extended X-ray emission at z spec = 2.506, which contains 11 massive (M * ≳ 1011 M ⊙) galaxies in the central 80 kpc region (11.6σ overdensity). We have spectroscopically confirmed 17 member galaxies with 11 from CO and the remaining ones from Hα. The X-ray luminosity, stellar mass content, and velocity dispersion all point to a collapsed, cluster-sized dark matter halo with mass M 200c = 1013.9±0.2 M ⊙, making it the most distant X-ray-detected cluster known to date. Unlike other clusters discovered so far, this structure is dominated by star-forming galaxies (SFGs) in the core with only 2 out of the 11 massive galaxies classified as quiescent. The star formation rate (SFR) in the 80 kpc core reaches ∼3400 M ⊙ yr‑1 with a gas depletion time of ∼200 Myr, suggesting that we caught this cluster in rapid build-up of a dense core. The high SFR is driven by both a high abundance of SFGs and a higher starburst fraction (∼25%, compared to 3%–5% in the field). The presence of both a collapsed, cluster-sized halo and a predominant population of massive SFGs suggests that this structure could represent an important transition phase between protoclusters and mature clusters. It provides evidence that the main phase of massive galaxy passivization will take place after galaxies accrete onto the cluster, providing new insights into massive cluster formation at early epochs. The large integrated stellar mass at such high redshift challenges our understanding of massive cluster formation.

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

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

    2011-01-01

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

  10. Detection of Faint BLR Components in the Starburst/Seyfert Galaxy NGC 6221 and Measure of the Central BH Mass

    La Franca, Fabio; Ricci, Federica; Bianchi, Stefano; Marconi, Alessandro; Sani, Eleonora; Vignali, Cristian

    2016-01-01

    In the last decade, using single epoch virial based techniques in the optical band, it has been possible to measure the central black hole mass on large AGN1 samples. However these measurements use the width of the broad line region as a proxy of the virial velocities and are therefore difficult to be carried out on those obscured (type 2) or low luminosity AGN where the nuclear component does not dominate in the optical. Here we present the optical and near infrared spectrum of the starburst/Seyfert galaxy NGC 6221, observed with X-shooter/VLT. Previous observations of NGC 6221 in the X-ray band show an absorbed (N_H=8.5 +/- 0.4 x 10^21 cm^-2) spectrum typical of a type 2 AGN with luminosity log(L_14-195 keV) = 42.05 erg/s, while in the optical band its spectrum is typical of a reddened (A_V=3) starburst. Our deep X-shooter/VLT observations have allowed us to detect faint broad emission in the H_alpha, HeI and Pa_beta lines (FWHM ~1400-2300 km/s) confirming previous studies indicating that NGC 6221 is a redd...

  11. Neutral carbon and CO in 76 (U)LIRGs and starburst galaxy centers A method to determine molecular gas properties in luminous galaxies

    Israel, F P; van der Werf, P

    2015-01-01

    We present fluxes in both neutral carbon [CI] lines at the centers of 76 galaxies with FIR luminosities between 10^{9} and 10^{12} L(o) obtained with Herschel-SPIRE and with ground-based facilities, along with the J=7-6, J=4-3, J=2-1 12CO and J=2-1 13CO line fluxes. We investigate whether these lines can be used to characterize the molecular ISM of the parent galaxies in simple ways and how the molecular gas properties define the model results. In most starburst galaxies, the [CI]/13CO flux ratio is much higher than in Galactic star-forming regions, and it is correlated to the total FIR luminosity. The [CI](1-0)/CO(4-3), the [CI](2-1) (2-1)/CO(7-6), and the [CI] (2-1)/(1-0) flux ratios are also correlated, and trace the excitation of the molecular gas. In the most luminous infrared galaxies (LIRGs), the ISM is fully dominated by dense and moderately warm gas clouds that appear to have low [C]/[CO] and [13CO]/[12CO] abundances. In less luminous galaxies, emission from gas clouds at lower densities becomes prog...

  12. Prototypes for infrared astronomical spectroscopy: A starburst galaxy, a data acquisition system, and a data reduction system

    Achtermann, Jeffrey Mark

    1994-01-01

    Over the last twenty years advances in detector technology have transformed infrared astronomy from a curiosity into a valuable tool of modern astronomy. This change also required advancements in three key areas: data acquisition systems, data reduction systems, and the astronomical interpretation of infrared observations. A data acquisition system based on digital signal processors (DSPs) and capable of accommodating the high throughput of infrared arrays was constructed. By using off-the-shelf components, system design was simplified, construction time and cost were reduced, and reliability was increased. The use of DSPs shifts much of the functionality and development work from hardware to software. The acquisition software is a distributed system running on two Sun SPARCstations and two DSP cards containing Motorola DSP56001s. The data acquisition software takes advantage of the object-oriented features of C++ to modularize the software system. The modularity of this system allows it to be easily adapted to other telescopes and/or arrays. A general astronomical reduction system was created. The system allows the easily manipulation of three dimensional arrays in mathematical expressions, can automatically process data taken in the common infrared observing modes, and provides a uniquely flexible plotting interface which allows data to be viewed as spectra, contour plots, color images, or as a 'movie'. Observations of (Ne-II)(12.8 micro-m), (Ar-III)(8.99 micro-m), (S-IV)(10.51 micro-m), and Hydrogen Bra (4.06 micro-m) were used to probe the excitation and kinematics within the starburst nucleus of M82. The temperature of the stars ionizing the starburst region is approximately 33,000 K, cooler than most Galactic H-II regions. This may be the result of either in initial mass function that does not produce high mass stars or the termination of the starburst 4 x 106 years ago. Within the starburst region, the ionized gas is distributed in a nuclear ring and two

  13. Ionization Parameter as a Diagnostic of Radiation and Wind Pressures in H II Regions and Starburst Galaxies

    Yeh, Sherry C C

    2012-01-01

    The ionization parameter U is potentially useful for measuring radiation pressure feedback from massive star clusters, as it reflects the radiation-to-gas-pressure ratio and is readily derived from mid-infrared line ratios. We consider several effects which determine the apparent value of U in HII regions and galaxies. An upper limit is set by the compression of gas by radiation pressure. The pressure from stellar winds and the presence of neutral clumps both reduce U for a given radiation intensity. The most intensely irradiated regions are selectively dimmed by internal dust absorption of ionizing photons, inducing observational bias on galactic scales. We explore these effects analytically and numerically, and use them to interpret previous observational results. We find that radiation confinement sets the upper limit log_10 U = -1 seen in individual regions. Unresolved starbursts display a maximum value of ~ -2.3. While lower, this is also consistent with a large portion of their HII regions being radiati...

  14. DETECTION OF GAMMA-RAY EMISSION FROM THE STARBURST GALAXIES M82 AND NGC 253 WITH THE LARGE AREA TELESCOPE ON FERMI

    We report the detection of high-energy γ-ray emission from two starburst galaxies using data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Steady point-like emission above 200 MeV has been detected at significance levels of 6.8σ and 4.8σ, respectively, from sources positionally coincident with locations of the starburst galaxies M82 and NGC 253. The total fluxes of the sources are consistent with γ-ray emission originating from the interaction of cosmic rays with local interstellar gas and radiation fields and constitute evidence for a link between massive star formation and γ-ray emission in star-forming galaxies.

  15. AKARI Near-Infrared Spectroscopic Observations of Interstellar Ices in Edge-on Starburst Galaxy NGC253

    Yamagishi, Mitsuyoshi; Ishihara, Daisuke; Oyabu, Shinki; Onaka, Takashi; Shimonishi, Takashi; Suzuki, Toyoaki

    2011-01-01

    We present the spatially-resolved near-infrared (2.5-5.0 um) spectra of the edge-on starburst galaxy NGC253 obtained with the Infrared Camera onboard AKARI. Near the center of the galaxy, we clearly detect the absorption features of interstellar ices (H_2O: 3.05 um, CO_2: 4.27 um, and XCN: 4.62 um) and the emission of polycyclic aromatic hydrocarbons (PAHs) at 3.29 um and hydrogen recombination line Br alpha at 4.05 um. We find that the distributions of the ices differ from those of the PAH and gas. We calculate the column densities of the ices and derive the abundance ratios of N(CO_2)/N(H_2O) = 0.17 +- 0.05. They are similar to those obtained around the massive young stellar objects in our Galaxy (0.17 +- 0.03), although much stronger interstellar radiation field and higher dust temperature are expected near the center of NGC253.

  16. On carbon and oxygen isotope ratios in starburst galaxies: New data from NGC253 and Mrk231 and their implications

    Henkel, C; Ao, Y; Aalto, S; Danielson, A L R; Papadopoulos, P P; Garcia-Burillo, S; Aladro, R; Impellizzeri, C M V; Mauersberger, R; Martin, S; Harada, N

    2014-01-01

    Using the IRAM 30-m telescope, CN and CO isotopologues have been measured toward the central regions of the nearby starburst galaxy NGC253 and the prototypical ultraluminous infrared galaxy Mrk231. In NGC253, the 12C/13C ratio is 40+-10. Assuming that the ratio also holds for the CO emitting gas, this yields 16O/18O = 145+-36 and 16O/17O = 1290+-365 and a 32S/34S ratio close to that measured for the local interstellar medium (20-25). No indication for vibrationally excited CN is found. Peak line intensity ratios between NGC253 and Mrk231 are ~100 for 12C16O and 12C18O J=1-0, while the ratio for 13C16O J=1-0 is ~250. This and similar 13CO and C18O line intensities in the J=1-0 and 2-1 transitions of Mrk231 suggest 12C/13C ~ 100 and 16O/18O ~ 100, in agreement with values obtained for the less evolved ultraluminous merger Arp220. Also accounting for other extragalactic data, 12C/13C ratios appear to vary over a full order of magnitude, from >100 in ultraluminous high redshift galaxies to ~100 in more local such...

  17. Parsec-Scale Radio Emission from the Low-Luminosity Active Galactic Nucleus in the Dwarf Starburst Galaxy Henize 2-10

    Reines, Amy E.; Deller, Adam T.

    2012-01-01

    A candidate accreting massive black hole (BH) with M_BH ~ 10^6 Msun has recently been identified at the center of the dwarf starburst galaxy Henize 2-10 (He 2-10). This discovery offers the first possibility of studying a growing BH in a nearby galaxy resembling those in the earlier universe, and opens up a new class of host galaxies to search for the smallest supermassive BHs. Here we present very long baseline interferometry observations of He 2-10 taken with the Long Baseline Array (LBA) a...

  18. High luminosity IRAS galaxies - II. Optical spectroscopy, modelling of starburst regions and comparison with structure

    We have obtained moderate-resolution spectrophotometry, and here present various emission-line ratios and emission-line luminosities, for a complete sample of (predominantly high-luminosity) IRAS galaxies. Line ratio diagnostic diagrams show most to exhibit H II region-like spectra, although about 12 per cent are Seyferts or LINERs. The fraction of active galaxies does not appear to be a function of IR luminosity. The typical extinction, as derived from Hα/Hβ, is Av∼1. Comparison of the (0 III)/Hβ line ratios of IRAS galaxies with those of an optically selected sample of H II region-like galaxies shows the IRAS galaxies to be of lower ionization, which may be due to either higher metallicities or their high dust content. The IRAS galaxies show a range of optical colours, with the majority having colours similar to Sc galaxies. (author)

  19. WHAT DO THE STAR FORMATION HISTORIES OF GALAXIES TELL US ABOUT THE STARBURST-AGN CONNECTION?

    J. P. Torres-Papaqui

    2013-01-01

    Full Text Available We have determined the normal star formation histories (SFHs for narrow emission line galaxies classified as star forming galaxies (SFGs, transition type objects (TOs, Seyfert 2s (Sy2s and LINERs. The SFH varied with the activity type, following the mass of the galaxies and the importance of their bulge: LINERs reside in massive early-type galaxies, Sy2s and TOs in intermediate mass galaxies with intermediate morphological types, and SFGs are hosted in lower mass late-type spirals. Also, the maximum star formation rate in the past was found to increase with the virial mass within the aperture (VMA. This correlation suggests that the bulges and the supermassive black holes at the center of galaxies grow in parallel, in good agreement with the MBH -σ∗ relation.

  20. MUSE Reveals a Recent Merger in the Post-starburst Host Galaxy of the TDE ASASSN-14li

    Prieto, J L; Anderson, J P; Galbany, L; Kochanek, C S; Aquino, E; Brown, J S; Dong, Subo; Förster, F; Holoien, T W -S; Kuncarayakti, H; Maureira, J C; Rosales-Ortega, F F; Sánchez, S F; Shappee, B J; Stanek, K Z

    2016-01-01

    We present MUSE integral field spectroscopic observations of the host galaxy (PGC 043234) of one of the closest ($z=0.0206$, $D\\simeq 90$ Mpc) and best-studied tidal disruption events (TDE), ASASSN-14li. The MUSE integral field data reveal asymmetric and filamentary structures that extend up to $\\gtrsim 10$ kpc from the post-starburst host galaxy of ASASSN-14li. The structures are traced only through the strong nebular [O III] $\\lambda$5007, [N II] $\\lambda$6584, and H$\\alpha$ emission lines. The total off nuclear [O III] $\\lambda$5007 luminosity is luminosity is $4.7\\times 10^{39}$ erg s$^{-1}$ and the ionized H mass is $\\rm \\sim 10^4(500/n_e)\\,M_{\\odot}$. Based on the BPT diagram, the nebular emission can be driven by either AGN photoionization or shock excitation, with AGN photoionization favored given the narrow intrinsic line widths. The emission line ratios and spatial distribution strongly resemble ionization nebulae around fading AGNs such as IC 2497 (Hanny's Voorwerp) and ionization "cones" around Se...

  1. X-ray sources in the starburst spiral galaxy M83 nuclear region and discrete source population

    Soria, R; Soria, Roberto; Wu, Kinwah

    2002-01-01

    Chandra has resolved the starburst nuclear region of the face-on grand-design spiral M83. Eighty-one point sources are detected above 3.5 sigma in the ACIS S3 image, and 15 of them are within the inner 16-arcsec region of the galaxy. A point source with L_x ~ 3 x 10^(38) erg/s in the 0.3--8.0 keV band is found to coincide with the infra-red nuclear photometric peak, one of the two dynamical nuclei of the galaxy. No point-like sources are resolved (at a 2.5-sigma level) at the centre of symmetry of the outer optical isophote ellipses, suspected to be another dynamical nucleus. About 50% of the total emission in the nuclear region is unresolved; of this, about 70% can be attributed to hot thermal plasma, and the rest is probably due to unresolved point sources (eg, faint X-ray binaries). The azimuthally-averaged radial distribution of the unresolved emission has a King-like profile, with no central cusp. Strong emission lines are seen in the spectrum of the optically thin plasma component. The high abundances o...

  2. IC10: the history of the nearest starburst galaxy through its Planetary Nebula and HII region populations

    Magrini, Laura; Gonçalves, Denise R.

    2009-09-01

    We report the results of spectroscopic observations, obtained with the Gemini North Multi-Object Spectrograph, of nine planetary nebulae (PNe) and 15 HII regions located in the 5.5 × 5.5arcmin2 inner region of the nearby starburst galaxy IC10. Twelve new candidates PNe have been discovered during our pre-imaging phase. Nine of them have been spectroscopically confirmed. The direct availability of the electron temperature diagnostics in several nebulae allowed an accurate determination of the metallicity map of IC10 at two epochs: the present-time from HII regions and the old/intermediate-age from PNe. We found a non-homogeneous distribution of metals at both epochs, but similar average abundances were found for the two populations. The derived age-metallicity relation shows a little global enrichment interpreted as the loss of metals by supernova winds and to differential gas outflows. Finally, we analysed the production of oxygen - through the third dredge-up - in the chemical abundance patterns of the PN populations belonging to several dwarf irregular galaxies. We found that the third dredge-up of oxygen is a metallicity dependent phenomenon occurring mainly for 12 + log(O/H) arcetri.astro.it

  3. Molecular gas in low-metallicity starburst galaxies:. Scaling relations and the CO-to-H2 conversion factor

    Amorín, R.; Muñoz-Tuñón, C.; Aguerri, J. A. L.; Planesas, P.

    2016-04-01

    Context. Tracing the molecular gas-phase in low-mass star-forming galaxies becomes extremely challenging due to significant UV photo-dissociation of CO molecules in their low-dust, low-metallicity ISM environments. Aims: We aim to study the molecular content and the star-formation efficiency of a representative sample of 21 blue compact dwarf galaxies (BCDs), previously characterized on the basis of their spectrophotometric properties. Methods: We present CO (1-0) and (2-1) observations conducted at the IRAM-30m telescope. These data are further supplemented with additional CO measurements and multiwavelength ancillary data from the literature. We explore correlations between the derived CO luminosities and several galaxy-averaged properties. Results: We detect CO emission in seven out of ten BCDs observed. For two galaxies these are the first CO detections reported so far. We find the molecular content traced by CO to be correlated with the stellar and Hi masses, star formation rate (SFR) tracers, the projected size of the starburst, and its gas-phase metallicity. BCDs appear to be systematically offset from the Schmidt-Kennicutt (SK) law, showing lower average gas surface densities for a given ΣSFR, and therefore showing extremely low (≲0.1 Gyr) H2 and H2 +Hi depletion timescales. The departure from the SK law is smaller when considering H2 +Hi rather than H2 only, and is larger for BCDs with lower metallicity and higher specific SFR. Thus, the molecular fraction (ΣH2/ ΣHI) and CO depletion timescale (ΣH2/ ΣSFR) of BCDs is found to be strongly correlated with metallicity. Using this, and assuming that the empirical correlation found between the specific SFR and galaxy-averaged H2 depletion timescale of more metal-rich galaxies extends to lower masses, we derive a metallicity-dependent CO-to-H2 conversion factor αCO,Z ∝ (Z/Z⊙)- y, with y = 1.5(±0.3)in qualitative agreement with previous determinations, dust-based measurements, and recent model

  4. Hubble space telescope grism spectroscopy of extreme starbursts across cosmic time: The role of dwarf galaxies in the star formation history of the universe

    Near infrared slitless spectroscopy with the Wide Field Camera 3, on board the Hubble Space Telescope, offers a unique opportunity to study low-mass galaxy populations at high redshift (z ∼ 1-2). While most high-z surveys are biased toward massive galaxies, we are able to select sources via their emission lines that have very faint continua. We investigate the star formation rate (SFR)-stellar mass (M*) relation for about 1000 emission line galaxies identified over a wide redshift range of 0.3 ≲ z ≲ 2.3. We use the Hα emission as an accurate SFR indicator and correct the broadband photometry for the strong nebular contribution to derive accurate stellar masses down to M* ∼107 M☉. We focus here on a subsample of galaxies that show extremely strong emission lines (EELGs) with rest-frame equivalent widths ranging from 200 to 1500 Å. This population consists of outliers to the normal SFR-M* sequence with much higher specific SFRs (>10 Gyr–1). While on-sequence galaxies follow continuous star formation processes, EELGs are thought to be caught during an extreme burst of star formation that can double their stellar mass in a period of less than 100 Myr. The contribution of the starburst population to the total star formation density appears to be larger than what has been reported for more massive galaxies in previous studies. In the complete mass range 8.2 < log(M*/M☉) <10 and a SFR lower completeness limit of about 2 M☉ yr–1 (10 M☉ yr–1) at z ∼ 1 (z ∼ 2), we find that starbursts having EWrest(Hα) > 300, 200, and 100 Å contribute up to ∼13%, 18%, and 34%, respectively, to the total SFR of emission-line-selected sample at z ∼ 1-2. The comparison with samples of massive galaxies shows an increase in the contribution of starbursts toward lower masses.

  5. Charge-exchange emission in the starburst galaxies M82 and NGC3256

    Ranalli, Piero

    2012-01-01

    Charge-exchange (CE) emission produces features which are detectable with the current X-ray instrumentation in the brightest near galaxies. We describe these aspects in the observed X-ray spectra of the star forming galaxies M82 and NGC 3256, from the Suzaku and XMM-Newton telescopes. Emission from both ions (O, C) and neutrals (Mg, Si) is recognised. We also describe how microcalorimeter instrumentation on future missions will improve CE observations.

  6. The far infra-red SEDs of main sequence and starburst galaxies

    Cowley, William I; Lagos, Claudia del P; Lacey, Cedric G; Baugh, Carlton M; Cole, Shaun

    2016-01-01

    We compare observed far infra-red/sub-millimetre (FIR/sub-mm) galaxy spectral energy distributions (SEDs) of massive galaxies ($M_{\\star}\\gtrsim10^{10}$ $h^{-1}$M$_{\\odot}$) derived through a stacking analysis with predictions from a new model of galaxy formation. The FIR SEDs of the model galaxies are calculated using a self-consistent model for the absorption and re-emission of radiation by interstellar dust based on radiative transfer calculations and global energy balance arguments. Galaxies are selected based on their position on the specific star formation rate (sSFR) - stellar mass ($M_{\\star}$) plane. We identify a main sequence of star-forming galaxies in the model, i.e. a well defined relationship between sSFR and $M_\\star$, up to redshift $z\\sim6$. The scatter of this relationship evolves such that it is generally larger at higher stellar masses and higher redshifts. There is remarkable agreement between the predicted and observed average SEDs across a broad range of redshifts ($0.5\\lesssim z\\lesss...

  7. ALMA Reveals Weak [NII] Emission in "Typical" Galaxies and Intense Starbursts at z=5-6

    Pavesi, Riccardo; Capak, Peter L; Carilli, Christopher L; Sharon, Chelsea E; Stacey, Gordon J; Karim, Alexander; Scoville, Nicholas Z; Smolcic, Vernesa

    2016-01-01

    We report interferometric measurements of [NII] 205 um fine-structure line emission from a representative sample of three galaxies at z=5-6 using the Atacama Large (sub)Millimeter Array (ALMA). These galaxies were previously detected in [CII] and far-infrared continuum emission and span almost two orders of magnitude in star formation rate (SFR). Our results show at least two different regimes of ionized inter-stellar medium properties for galaxies in the first billion years of cosmic time, separated by their L_[CII]/L_[NII] ratio. We find extremely low [NII] emission compared to [CII] (L_ [CII]/L_[NII]=68 [+200/-28]) from a "typical" L*_UV star-forming galaxy, likely directly or indirectly (by its effect on the radiation field) related to low dust abundance and low metallicity. The infrared-luminous modestly star-forming Lyman Break Galaxy (LBG) in our sample is characterized by an ionized-gas fraction (L_[CII]/L_[NII]<=20) typical of local star-forming galaxies and shows evidence for spatial variations i...

  8. The Spatially Resolved Dynamics of Dusty Starburst Galaxies in a z ~ 0.4 Cluster: Beginning the Transition from Spirals to S0s

    Johnson, H.L.; Harrison, C. M.; Swinbank, A. M.; Bower, R. G.; Smail, Ian; Y. Koyama; Geach, J. E.

    2016-01-01

    To investigate what drives the reversal of the morphology-density relation at intermediate/high redshift, we present a multi-wavelength analysis of 27 dusty starburst galaxies in the massive cluster Cl 0024+17 at z = 0.4. We combine H-alpha dynamical maps from the VLT/FLAMES multi-IFU system with far-infrared imaging using Herschel SPIRE and millimetre spectroscopy from IRAM/NOEMA, in order to measure the dynamics, star formation rates and gas masses of this sample. Most galaxies appear to be...

  9. Neutral carbon and CO in 76 (U)LIRGs and starburst galaxy centers. A method to determine molecular gas properties in luminous galaxies

    Israel, F. P.; Rosenberg, M. J. F.; van der Werf, P.

    2015-06-01

    In this paper we present fluxes in the [ CI ] lines of neutral carbon at the centers of some 76 galaxies with far-infrared luminosities ranging from 109 to 1012L⊙, as obtained with the Herschel Space Observatory and ground-based facilities, along with the line fluxes of the J = 7-6, J = 4-3, J = 2-112CO, and J = 2-113CO transitions. With this dataset, we determine the behavior of the observed lines with respect to each other and then investigate whether they can be used to characterize the molecular interstellar medium (ISM) of the parent galaxies in simple ways and how the molecular gas properties define the model results. In most starburst galaxies, the [ CI ] to 13CO line flux ratio is much higher than in Galactic star-forming regions, and it is correlated to the total far-infrared luminosity. The [ CI ] (1-0)/12CO (4-3), the [ CI ] (2-1)/12CO (7-6), and the [ CI ] (2-1)/(1-0) flux ratios are correlated, and they trace the excitation of the molecular gas. In the most luminous infrared galaxies (LIRGs), the ISM is fully dominated by dense (n( H2) = 104-105 cm-3) and moderately warm (Tkin ≈ 30 K) gas clouds that appear to have low [C°]/[CO] and [13CO]/[12CO] abundances. In less luminous galaxies, emission from gas clouds at lower densities becomes progressively more important, and a multiple-phase analysis is required to determine consistent physical characteristics. Neither the 12CO nor the [ CI ] velocity-integrated line fluxes are good predictors of molecular hydrogen column densities in individual galaxies. In particular, so-called X( [ CI ]) conversion factors are not superior to X( 12CO) factors. The methods and diagnostic diagrams outlined in this paper also provide a new and relatively straightforward means of deriving the physical characteristics of molecular gas in high-redshift galaxies up to z = 5, which are otherwise hard to determine.

  10. Discovery of a galaxy cluster with a violently starbursting core at z=2.506

    Wang, Tao; Daddi, Emanuele; Finoguenov, Alexis; Liu, Daizhong; Schreiber, Corentin; Martin, Sergio; Strazzullo, Veronica; Valentino, Francesco; van der Burg, Remco; Zanella, Anita; Ciesla, Laure; Gobat, Raphael; Brun, Amandine Le; Pannella, Maurillio; Sargent, Mark; Tan, Xinwen Shu Qinghua; Cappelluti, Nico; Li, Yanxia

    2016-01-01

    We report the discovery of a remarkable concentration of massive galaxies with extended X-ray emission at $z_{spec} = 2.506$ in the COSMOS field. This structure contains in its center 11 massive ($M_{*} \\gtrsim 10^{11} M_{\\odot}$) galaxies distributed over 80-kpc, producing an 11.6$\\sigma$ overdensity. We have spectroscopically confirmed 16 member galaxies extending to $\\sim1$ Mpc from the core with half of them derived from CO with IRAM-NOEMA and JVLA and the other half from $H\\alpha$ with VLT-KMOS. The X-ray luminosity, high stellar mass content and velocity dispersion all point to a collapsed, single cluster-sized dark matter halo with total mass $M_{200c} \\sim 10^{13.9\\pm0.2} M_{\\odot}$, identifying it as the most distant X-ray detected cluster known to date. Unlike other clusters discovered so far, this structure is dominated by star-forming galaxies in the core with only two out of the 11 massive galaxies classified as quiescent. The star formation rate in the 80-kpc core reaches $\\sim$3400 $M_{\\odot}$ ...

  11. The Starburst in the Abell 1835 Cluster Central Galaxy: A Case Study of Galaxy Formation Regulated by an Outburst from a Supermassive Black Hole

    McNamara, B R; Carilli, C L; Nulsen, P E J; Rafferty, D A; Ryan, R; Sharma, M; Steiner, J; Wise, M W

    2006-01-01

    We present an optical, X-ray, and radio analysis of the starburst in the Abell 1835 cluster's central cD galaxy. The dense gas surrounding the galaxy is radiating X-rays with a luminosity of ~1E45 erg/s consistent with a cooling rate of ~1000-2000 solar masses per year. However, new Chandra and XMM-Newton observations find less than 200 solar masses per year of gas cooling below ~2 keV, a level that is consistent with the cD's current star formation rate of 100-180 solar masses per year. One or more heating agents (feedback) must then be replenishing the remaining radiative losses. The heat fluxes from supernova explosions and thermal conduction alone are unable to do so. However, a pair of X-ray cavities from an AGN outburst has deposited ~1.7E60 erg into the surrounding gas over the past 40 Myr. The corresponding jet power 1.4E45 erg/sec is enough to offset most of the radiative losses from the cooling gas. The jet power exceeds the radio synchrotron power by ~4000 times, making this one of the most radiati...

  12. A population of intermediate-mass black holes in dwarf starburst galaxies up to redshift=1.5

    Mezcua, M; Fabbiano, G; Miyaji, T; Marchesi, S

    2015-01-01

    We study a sample of $\\sim$50,000 dwarf starburst and late-type galaxies drawn from the COSMOS survey with the aim of investigating the presence of nuclear accreting black holes (BHs) as those seed BHs from which supermassive BHs could grow in the early Universe. We divide the sample into five complete redshift bins up to $z=1.5$ and perform an X-ray stacking analysis using the \\textit{Chandra} COSMOS-Legacy survey data. After removing the contribution from X-ray binaries and hot gas to the stacked X-ray emission, we still find an X-ray excess in the five redshift bins that can be explained by nuclear accreting BHs. This X-ray excess is more significant for $z<0.5$. At higher redshifts, these active galactic nuclei could suffer mild obscuration, as indicated by the analysis of their hardness ratios. The average nuclear X-ray luminosities in the soft band are in the range 10$^{39}-10^{40}$ erg s$^{-1}$. Assuming that the sources accrete at $\\geq$ 1\\% the Eddington rate, their BH masses would be $\\leq$ 10$^{...

  13. Galactic mergers, starburst galaxies, quasar activity and massive binary black holes

    Many quasar-like objects show evidence for massive binary black holes. The recent discovery of a massive (5 X 106 Msolar mass) object in the centre of the local group dwarf elliptical M 32 greatly raises the probability of forming such binaries through galactic mergers. The author argues that the enhancement of all kinds of activity (quasar-like activity and star formation) in galaxies with companions is not so much a consequence of tidal interaction between the massive galaxies as the result of collisions with their dwarf satellites. (author)

  14. VCC 144 - a star-bursting dwarf galaxy in the Virgo Cluster

    Brosch, N.; Almoznino, E.; L. Hoffman

    1997-01-01

    We describe results of a multi-spectral study of a blue compact dwarf galaxy in Virgo. The object was observed with broad-band and H$\\alpha$ imaging, UV observations, and radio synthesis. Our data were combined with published optical observations, with HI single-beam observation and with FIR data, and were compared to results of evolutionary synthesis programs. The radio observations revealed a compact source of HI coincident with the optical galaxy, embedded in a diffuse, HI cloud which has ...

  15. Mapping the starburst in Blue Compact Dwarf Galaxies. PMAS Integral Field Spectroscopy of Mrk 1418

    Cairos, L M; Zurita, C; Kehrig, C; Weilbacher, P; Roth, M

    2009-01-01

    (Abridged) Aims: By means of optical Integral Field Spectroscopy (IFS) observations, we aim to disentangle and characterize the starburst component in the BCD Mrk 1418. In particular we propose to study the stellar and ionized gas morphology, to investigate the ionization mechanism(s) acting in the interstellar medium, to derive the physical parameters and abundances of the ionized gas. Methods: IFS observations of Mrk 1418 were carried out with PMAS at the 3.5 m telescope at CAHA. The central 16"x16" were mapped. From these data we built maps of the most prominent emission lines, namely [OII], H-beta, [OIII], H-alpha, [NII] and [SII] as well as of several continuum bands, plus maps of the main line ratios: [OIII]/H-beta, [NII]/H-alpha, [SII]/H-alpha, and H-alpha/H-beta, and derived the physical parameters and gaseous metal abundances of the different star-forming regions detected in the field of view. Results: Mrk 1418 shows a distorted morphology both in the continuum and in the ionized gas maps; the curren...

  16. Multi-wavelength lens reconstruction of a Planck \\& \\textit{Herschel}-detected starbursting galaxy

    Timmons, Nicholas; Riechers, Dominik A; Nayyeri, Hooshang; Fu, Hai; Jullo, Eric; Gladders, Michael D; Baes, Maarten; Bussmann, R Shane; Calanog, Jae; Clements, David L; da Cunha, Elisabete; Dye, Simon; Eales, Stephen A; Furlanetto, Cristina; Gonzalez-Nuevo, Joaquin; Greenslade, Joshua; Gurwell, Mark; Michałowski, Michał J; Pérez-Fournon, Iván Oteo Ismael; Scott, Douglas; Valiante, Elisabetta

    2015-01-01

    We present a reconstruction of a {\\it Herschel} and Planck detected gravitationally-lensed dusty star-forming galaxy (DSFG) at $z=1.68$ using {\\it Hubble}, Sub-millimeter Array (SMA), and Keck observations. The background sub-millimeter galaxy (SMG) is strongly lensed by a foreground galaxy cluster at z=0.997 and appears as an arc of length $\\sim 15"$ in the optical images. The continuum dust emission, as seen by SMA, is limited to a single knot within this arc. We present a lens model with source plane reconstructions at several wavelengths to show the difference in magnifications between the stars and the dust and highlight the importance of a multi-wavelength lens models for studies involving lensed DSFGs. We estimate the physical properties of the galaxy by fitting the flux densities to model SEDs leading to a magnification-corrected star-formation rate of $390 \\pm 60$ M$_{\\odot}$yr$^{-1}$ and a stellar mass of $1.1 \\pm 0.4\\times 10^{11}$M$_{\\odot}$. These values are consistent with high-redshift massive ...

  17. An Extreme Starburst in the Core of a Rich Galaxy Cluster at z = 1.7

    Webb, Tracy; Noble, Allison; DeGroot, Andrew; Wilson, Gillian; Muzzin, Adam; Bonaventura, Nina; Cooper, Mike; Delahaye, Anna; Foltz, Ryan; Lidman, Chris; Surace, Jason; Yee, H. K. C.; Chapman, Scott; Dunne, Loretta; Geach, James; Hayden, Brian; Hildebrandt, Hendrik; Huang, Jiasheng; Pope, Alexandra; Smith, Matthew W. L.; Perlmutter, Saul; Tudorica, Alex

    2015-08-01

    We have discovered an optically rich galaxy cluster at z = 1.7089 with star formation occurring in close proximity to the central galaxy. The system, SpARCS104922.6+564032.5, was detected within the Spitzer Adaptation of the red-sequence Cluster Survey, and confirmed through Keck-MOSFIRE spectroscopy. The rest-frame optical richness of Ngal (500 kpc) = 30 ± 8 implies a total halo mass, within 500 kpc, of ˜3.8 ± 1.2 × 1014 M⊙, comparable to other clusters at or above this redshift. There is a wealth of ancillary data available, including Canada-France-Hawaii Telescope optical, UKIRT-K, Spitzer-IRAC/MIPS, and Herschel-SPIRE. This work adds submillimeter imaging with the SCUBA2 camera on the James Clerk Maxwell Telescope and near-infrared imaging with the Hubble Space Telescope. The mid/far-infrared (M/FIR) data detect an Ultra-luminous Infrared Galaxy spatially coincident with the central galaxy, with LIR = 6.2 ± 0.9 × 1012 L⊙. The detection of polycyclic aromatic hydrocarbons at z = 1.7 in a Spitzer-IRS spectrum of the source implies the FIR luminosity is dominated by star formation (an Active Galactic Nucleus contribution of 20%) with a rate of ˜860 ± 130 M⊙ yr-1. The optical source corresponding to the IR emission is likely a chain of >10 individual clumps arranged as “beads on a string” over a linear scale of 66 kpc. Its morphology and proximity to the Brightest Cluster Galaxy (BCG) imply a gas-rich interaction at the center of the cluster triggered the star formation. This system indicates that wet mergers may be an important process in forming the stellar mass of BCGs at early times.

  18. Star formation in infrared bright and infrared faint starburst interacting galaxies

    Lamb, Susan A.; Bushouse, Howard A.; Towns, John W.

    1990-01-01

    Short wavelength IUE spectra of Arp 248b and UGC 8315N are combined with optical spectra and interpreted using a combination of spectrum synthesis and spectral diagnostics to place constraints on the massive star populations of the central regions of these galaxies and to deduce information about the star formation histories in the last 10(exp 8) years. The authors find that both galaxies have substantial fractions of their optical light coming from massive stars and that Arp 248b may be dominated in the UV by WR stars. The UV spectra are dominated by radiation from evolved massive stars and the authors place and age on the burst in Arp 248b of a few tens of millions of years.

  19. AN INITIAL MASS FUNCTION STUDY OF THE DWARF STARBURST GALAXY NGC 4214

    Andrews, J. E.; Calzetti, D. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Chandar, R. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Lee, J. C.; Whitmore, B. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Elmegreen, B. G. [IBM T. J. Watson Research Center, Yorktown Heights, NY (United States); Kennicutt, R. C. [Institute of Astronomy, Cambridge University, Cambridge (United Kingdom); Kissel, J. S. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Da Silva, Robert L.; Krumholz, Mark R. [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); O' Connell, R. W. [Department of Astronomy, University of Virginia, P.O. Box 3818, Charlottesville, VA 22903 (United States); Dopita, M. A. [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Frogel, Jay A. [Galaxies Unlimited, 1 Tremblant Court, Lutherville, MD (United States); Kim, Hwihyun, E-mail: jandrews@astro.umass.edu, E-mail: callzetti@astro.umass.edu [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States)

    2013-04-10

    The production rate of ionizing photons in young ({<=}8 Myr), unresolved stellar clusters in the nearby irregular galaxy NGC 4214 is probed using multi-wavelength Hubble Space Telescope WFC3 data. We normalize the ionizing photon rate by the cluster mass to investigate the upper end of the stellar initial mass function (IMF). We have found that within the uncertainties the upper end of the stellar IMF appears to be universal in this galaxy, and that deviations from a universal IMF can be attributed to stochastic sampling of stars in clusters with masses {approx}<10{sup 3} M{sub Sun }. Furthermore, we have found that there does not seem to be a dependence of the maximum stellar mass on the cluster mass. We have also found that for massive clusters, feedback may cause an underrepresentation in H{alpha} luminosities, which needs to be taken into account when conducting this type of analysis.

  20. Extra-nuclear starbursts: young luminous Hinge clumps in interacting galaxies

    Smith, Beverly J.; Giroux, Mark L. [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37614 (United States); Soria, Roberto [Curtin Institute of Radio Astronomy, Curtin University, 1 Turner Avenue, Bentley, WA 6102 (Australia); Struck, Curtis [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Swartz, Douglas A. [University Space Research Association, NASA Marshall Space Flight Center, ZP 12, Huntsville, AL (United States); Yukita, Mihoko, E-mail: smithbj@etsu.edu, E-mail: girouxm@etsu.edu, E-mail: rsoria@physics.usyd.edu.au, E-mail: curt@iastate.edu, E-mail: myukita1@pha.jhu.edu [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2014-03-01

    Hinge clumps are luminous knots of star formation near the base of tidal features in some interacting galaxies. We use archival Hubble Space Telescope (HST) UV/optical/IR images and Chandra X-ray maps along with Galaxy Evolution Explorer UV, Spitzer IR, and ground-based optical/near-IR images to investigate the star forming properties in a sample of 12 hinge clumps in five interacting galaxies. The most extreme of these hinge clumps have star formation rates of 1-9 M {sub ☉} yr{sup –1}, comparable to or larger than the 'overlap' region of intense star formation between the two disks of the colliding galaxy system the Antennae. In the HST images, we have found remarkably large and luminous sources at the centers of these hinge clumps. These objects are much larger and more luminous than typical 'super star clusters' in interacting galaxies, and are sometimes embedded in a linear ridge of fainter star clusters, consistent with star formation along a narrow caustic. These central sources have FWHM diameters of ∼70 pc, compared to ∼3 pc in 'ordinary' super star clusters. Their absolute I magnitudes range from M{sub I} ∼ – 12.2 to –16.5; thus, if they are individual star clusters they would lie near the top of the 'super star cluster' luminosity function of star clusters. These sources may not be individual star clusters, but instead may be tightly packed groups of clusters that are blended together in the HST images. Comparison to population synthesis modeling indicates that the hinge clumps contain a range of stellar ages. This is consistent with expectations based on models of galaxy interactions, which suggest that star formation may be prolonged in these regions. In the Chandra images, we have found strong X-ray emission from several of these hinge clumps. In most cases, this emission is well-resolved with Chandra and has a thermal X-ray spectrum, thus it is likely due to hot gas associated with the star

  1. The Eddington Limit in Cosmic Rays: An Explanation for the Observed Faintness of Starbursting Galaxies

    Socrates, A; Ramirez-Ruiz, E; Socrates, Aristotle; Davis, Shane W.; Ramirez-Ruiz, Enrico

    2006-01-01

    We show that the luminosity of a star forming galaxy is capped by the production and subsequent expulsion of cosmic rays from its interstellar medium. By defining an Eddington luminosity in cosmic rays, we show that the star formation rate of a given galaxy is limited by its mass content and the cosmic ray mean free path. When the cosmic ray luminosity and pressure reaches a critical value as a result of vigorous star formation, hydrostatic balance is lost, a cosmic ray-driven wind develops, and star formation is choked off. Cosmic ray pressure-driven winds are likely to produce wind velocities significantly in excess of the galactic escape velocity. It is possible that cosmic ray feedback results in the Faber-Jackson relation for a plausible set of input parameters that describe cosmic ray production and transport, which are calibrated by observations of the Milky Way's interstellar cosmic rays.

  2. The Virtual Observatory as a Tool to Study Star Cluster Populations in Starburst Galaxies

    de Grijs, Richard; Alvensleben, Uta Fritze - v.

    2002-01-01

    The cluster luminosity function (CLF) is one of the most important diagnostics in the study of old globular and young compact star cluster populations. We are currently using ASTROVIRTEL to obtain CLFs in several optical and/or near-infrared passbands, and colour distributions. This will provide us with a powerful analytical tool for the determination of the violent star and cluster formation history of galaxies: we will address questions related to the universality of the globular CLF, the t...

  3. High-J CO Versus Far-Infrared Relations in Normal and Starburst Galaxies

    Liu, Daizhong; Isaak, Kate; Daddi, Emanuele; Yang, Chentao; Lu, Nanyao; van der Werf, Paul

    2015-01-01

    We present correlations between 9 CO transition ($J=4-3$ to $12-11$) lines and beam-matched far-infrared (FIR) luminosities ($L_{\\mathrm{FIR},\\,b}$) among 167 local galaxies, using Herschel SPIRE/FTS spectroscopic data and PACS photometry data. We adopt entire-galaxy FIR luminosities ($L_{\\mathrm{FIR},\\,e}$) from the {\\it{IRAS}} Revised Bright Galaxy Sample and correct to $L_{\\mathrm{FIR},\\,b}$ using PACS images to match the varying FTS beams. All 9 correlations between $L'_{\\mathrm{CO}}$ and $L_{\\mathrm{FIR},\\,b}$ are essentially linear, even for the highest transition $J=12-11$. This supports the notion that dense molecular gas ($n_{\\mathrm{H}_2}\\gtrsim10^{4-6}\\,cm^{-3}$) linearly correlates with the star formation rate (SFR). We divide the entire sample into three subsamples and find that smaller sample size can induce large difference in the correlation slopes. We also derive an average CO spectral line energy distribution (SLED) for the entire sample and discuss the implied average molecular gas properti...

  4. The essential signature of a massive starburst in a distant galaxy

    Solomon, P M; Carilli, C; Guélin, M

    2003-01-01

    Observations of carbon monoxide (CO) emission in high redshift (z>2) galaxies indicate the presence of large amounts of molecular gas. Many of these galaxies contain an active galactic nucleus (AGN) powered by accretion of gas onto a supermassive black hole, and a key question is whether their extremely high infrared luminosities result from the AGN, or from bursts of massive star formation (associated with the molecular gas), or both. In the Milky Way, high-mass stars form in the dense cores of interstellar molecular clouds; gas densities are n(H2)>105 cm-3 in the cores. Recent surveys show that virtually all galactic sites of high-mass star formation have similarly high densities. The bulk of the cloud material traced by CO observations is at a much lower density. In galaxies in the local Universe, the HCN(J=1-0) line is an effective tracer of the high-density molecular gas. Here we report observations of HCN emission in the early Universe from the infrared luminous 'Cloverleaf' quasar (at a redshift z=2.55...

  5. Dense Molecular Gas in Extreme Starburst Galaxies - What will we learn from Herschel?

    Greve, T R; Gao, Y; Radford, S J E

    2006-01-01

    Ultra Luminous Infra-Red Galaxies (ULIRGs) -- gas-rich mergers harboring the most extreme star-forming conditions encountered in the local Universe -- are thought to re-enact the galaxy formation processes we are only barely able to glimpse in the distant Universe. Combining new single-dish molecular line observations of 12CO, 13CO, HCO+, HCN, and CS towards the two ULIRGs Arp220 and NGC6240 with existing data in the literature, we have compiled the most extensive molecular line data-sets to date of such galaxies. The data allow us to put strong constraints on the properties of the dense star forming gas in these two systems, and compare the relative usefulness of CS, HCN and HCO+ as tracers of dense gas. In addition, we have build molecular line templates based on our observations, and demonstrate that Herschel/HI-FI will be able to detect the high-J transitions of most of the above molecules in a large sample of ULIRGs out to z<=0.5, assuming Arp220 and NGC6240 are representative of the ULIRG population ...

  6. An Extreme Starburst in Close Proximity to the Central Galaxy of a Rich Galaxy Cluster at z=1.7

    Webb, Tracy; DeGroot, Andrew; Wilson, Gillian; Muzzin, Adam; Bonaventura, Nina; Cooper, Mike; Delahaye, Anna; Foltz, Ryan; Lidman, Chris; Surace, Jason; Yee, H K C; Chapman, Scott; Dunne, Loretta; Geach, James; Hayden, Brian; Hildebrandt, Hendrik; Huang, Jiasheng; Pope, Alexandra; Smith, Matthew W L; Perlmutter, Saul; Tudorica, Alex

    2015-01-01

    We have discovered an optically rich galaxy cluster at z=1.7089 with star formation occurring in close proximity to the central galaxy. The system, SpARCS104922.6+564032.5, was detected within the Spitzer Adaptation of the red-sequence Cluster Survey, (SpARCS), and confirmed through Keck-MOSFIRE spectroscopy. The rest-frame optical richness of Ngal(500kpc) = 30+/-8 implies a total halo mass, within 500kpc, of ~3.8+/-1.2 x 10^14 Msun, comparable to other clusters at or above this redshift. There is a wealth of ancillary data available, including Canada-France-Hawaii Telescope optical, UKIRT-K, Spitzer-IRAC/MIPS, and Herschel-SPIRE. This work adds submillimeter imaging with the SCUBA2 camera on the James Clerk Maxwell Telescope and near-infrared imaging with the Hubble Space Telescope (HST). The mid/far-infrared (M/FIR) data detect an Ultra-luminous Infrared Galaxy spatially coincident with the central galaxy, with LIR = 6.2+/-0.9 x 10^12 Lsun. The detection of polycyclic aromatic hydrocarbons (PAHs) at z=1.7 i...

  7. X-ray source population study of the starburst galaxy M83 with XMM-Newton

    Ducci, L.; Sasaki, M.; Haberl, F.; Pietsch, W.

    2013-01-01

    We present the results obtained from the analysis of three XMM-Newton observations of M83. The aims of the paper are studying the X-ray source populations in M83 and calculating the X-ray luminosity functions of X-ray binaries for different regions of the galaxy. We detected 189 sources in the XMM-Newton field of view in the energy range of 0.2-12 keV. We constrained their nature by means of spectral analysis, hardness ratios, studies of the X-ray variability, and cross-correlations with cata...

  8. Spitzer observations of MAMBO galaxies: weeding out active nuclei in starbursting proto-ellipticals

    Ivison, R J; Serjeant, S; Bertoldi, F; Egami, E; Mortier, A M J; Alonso-Herrero, A; Barmby, P; Bei, L; Dole, H; Engelbracht, C W; Fazio, G G; Frayer, D T; Gordon, K D; Hines, D C; Huang, J S; Le Floc'h, E; Misselt, K A; Miyazaki, S; Morrison, J E; Papovich, C; Pérez-González, P G; Rieke, M J; Rieke, G H; Rigby, J; Rigopoulou, D; Smail, I; Wilson, G; Willner, S P

    2004-01-01

    We present Spitzer observations in five wavebands between 3.6 and 24um of an unbiased sample of 9 luminous, dusty galaxies selected at 1200um by the MAMBO camera on the IRAM 30-m telescope, a population akin to the well-known submm or `SCUBA' galaxies (hereafter SMGs). Owing to the coarse resolution of submm/mm instrumentation, SMGs have traditionally been difficult to identify at other wavelengths. We compare our multi-wavelength catalogs to show that the overlap between 24 and 1200um must be close to complete at these flux levels. We find that all (4/4) of the most secure >=4sigma SMGs have robust >=4sigma counterparts at 1.4GHz, while the fraction drops to 7/9 using all >=3sigma SMGs. We show that combining mid-IR and marginal (>=3sigma) radio detections provides plausible identifications in the remaining cases, enabling us to identify the complete sample. Accretion onto an obscured central engine is betrayed by the shape of the mid-IR continuum emission for several sources, confirming Spitzer's potential ...

  9. The discovery of SN2014J in the nearby starburst galaxy M82

    Goobar, A; Amanullah, R; Fossey, S J; Cao, Y; Perley, D A; Kasliwal, M M; Ferretti, R; Nugent, P E; Harris, C; Gal-Yam, A; Ofek, E O; Tendulkar, S P; Dennefeld, M; Valenti, S; Arcavi, I; Banerjee, D P K; Venkataraman, V; Joshi, V; Ashok, N M; Cenko, S B; Diaz, R F; Fremling, C; Horesh, A; Howell, D A; Kulkarni, S R; Papadogiannakis, S; Petrushevska, T; Sand, D; Sollerman, J; Stanishev, V; Bloom, J S; Surace, J; Cooke, B N; Pollack, G M; Wilde, M; Wright, T

    2014-01-01

    In this Letter, we report the discovery of SN2014J in the nearby galaxy M82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova over a wide range of the electromagnetic spectrum. The first set of optical, near-IR and mid-IR observations of SN2014J, orchestrated by the intermediate Palomar Transient Factory (iPTF), show that SN2014J is a spectroscopically normal Type Ia supernova, albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the lightcurve rise. Similarly to other highly reddened Type Ia supernovae, a low value of total-to-selective extinction, Rv < 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from HST with specia...

  10. An enhanced fraction of starbursting galaxies among high Eddington ratio AGNs

    Bernhard, E; Daddi, E; Ciesla, L; Schreiber, C

    2016-01-01

    We investigate the star-forming properties of 1620 X-ray selected AGN host galaxies as a function of their specific X-ray luminosity (i.e., X-ray luminosity per unit host stellar mass) -- a proxy of the Eddington ratio. Our motivation is to determine whether there is any evidence of a suppression of star-formation at high Eddington ratios, which may hint toward "AGN feedback" effects. Star-formation rates (SFRs) are derived from fits to Herschel-measured far-infrared spectral energy distributions, taking into account any contamination from the AGN. Herschel-undetected AGNs are included via stacking analyses to provide average SFRs in bins of redshift and specific X-ray luminosity (spanning $0.01 \\lesssim L_{\\rm X}/M_{\\ast} \\lesssim 100~L_{\\odot} ~M_{\\odot}^{-1}$). After normalising for the effects of mass and redshift arising from the evolving galaxy main sequence, we find that the SFRs of high specific luminosity AGNs are slightly enhanced compared to their lower specific luminosity counterparts. This sugges...

  11. Hubble space telescope grism spectroscopy of extreme starbursts across cosmic time: The role of dwarf galaxies in the star formation history of the universe

    Atek, Hakim; Kneib, Jean-Paul [Laboratoire d' Astrophysique, EPFL, CH-1290 Sauverny (Switzerland); Pacifici, Camilla [Yonsei University Observatory, Yonsei University, Seoul 120-749 (Korea, Republic of); Malkan, Matthew; Ross, Nathaniel [Department of Physics and Astronomy, University of California, Los Angeles, CA (United States); Charlot, Stephane; Lehnert, Matthew [UPMC-CNRS, UMR7095, Institut d' Astrophysique de Paris, F-75014 Paris (France); Lee, Janice [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bedregal, Alejandro [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Bunker, Andrew J. [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, OX13RH (United Kingdom); Colbert, James W.; Rafelski, Marc [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Dressler, Alan; McCarthy, Patrick [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Hathi, Nimish [Aix Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Martin, Crystal L. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Siana, Brian [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Teplitz, Harry I. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2014-07-10

    Near infrared slitless spectroscopy with the Wide Field Camera 3, on board the Hubble Space Telescope, offers a unique opportunity to study low-mass galaxy populations at high redshift (z ∼ 1-2). While most high-z surveys are biased toward massive galaxies, we are able to select sources via their emission lines that have very faint continua. We investigate the star formation rate (SFR)-stellar mass (M{sub *}) relation for about 1000 emission line galaxies identified over a wide redshift range of 0.3 ≲ z ≲ 2.3. We use the Hα emission as an accurate SFR indicator and correct the broadband photometry for the strong nebular contribution to derive accurate stellar masses down to M{sub *} ∼10{sup 7} M{sub ☉}. We focus here on a subsample of galaxies that show extremely strong emission lines (EELGs) with rest-frame equivalent widths ranging from 200 to 1500 Å. This population consists of outliers to the normal SFR-M{sub *} sequence with much higher specific SFRs (>10 Gyr{sup –1}). While on-sequence galaxies follow continuous star formation processes, EELGs are thought to be caught during an extreme burst of star formation that can double their stellar mass in a period of less than 100 Myr. The contribution of the starburst population to the total star formation density appears to be larger than what has been reported for more massive galaxies in previous studies. In the complete mass range 8.2 < log(M{sub *}/M{sub ☉}) <10 and a SFR lower completeness limit of about 2 M{sub ☉} yr{sup –1} (10 M{sub ☉} yr{sup –1}) at z ∼ 1 (z ∼ 2), we find that starbursts having EW{sub rest}(Hα) > 300, 200, and 100 Å contribute up to ∼13%, 18%, and 34%, respectively, to the total SFR of emission-line-selected sample at z ∼ 1-2. The comparison with samples of massive galaxies shows an increase in the contribution of starbursts toward lower masses.

  12. The state of the warm and cold gas in the extreme starburst at the core of the Phoenix galaxy cluster (SPT-CLJ2344-4243)

    We present new optical integral field spectroscopy (Gemini South) and submillimeter spectroscopy (Submillimeter Array) of the central galaxy in the Phoenix cluster (SPT-CLJ2344-4243). This cluster was previously reported to have a massive starburst (∼800 M ☉ yr–1) in the central, brightest cluster galaxy, most likely fueled by the rapidly cooling intracluster medium. These new data reveal a complex emission-line nebula, extending for >30 kpc from the central galaxy, detected at [O II]λλ3726, 3729, [O III]λλ4959, 5007, Hβ, Hγ, Hδ, [Ne III]λ3869, and He II λ4686. The total Hα luminosity, assuming Hα/Hβ = 2.85, is L Hα = 7.6 ± 0.4 ×1043 erg s–1, making this the most luminous emission-line nebula detected in the center of a cool core cluster. Overall, the relative fluxes of the low-ionization lines (e.g., [O II], Hβ) to the UV continuum are consistent with photoionization by young stars. In both the center of the galaxy and in a newly discovered highly ionized plume to the north of the galaxy, the ionization ratios are consistent with both shocks and active galactic nucleus (AGN) photoionization. We speculate that this extended plume may be a galactic wind, driven and partially photoionized by both the starburst and central AGN. Throughout the cluster we measure elevated high-ionization line ratios (e.g., He II/Hβ, [O III]/Hβ), coupled with an overall high-velocity width (FWHM ≳ 500 km s–1), suggesting that shocks are likely important throughout the interstellar medium of the central galaxy. These shocks are most likely driven by a combination of stellar winds from massive young stars, core-collapse supernovae, and the central AGN. In addition to the warm, ionized gas, we detect a substantial amount of cold, molecular gas via the CO(3-2) transition, coincident in position with the galaxy center. We infer a molecular gas mass of MH2 = 2.2 ± 0.6 × 1010 M ☉, which implies that the starburst will consume its fuel in ∼30 Myr if it is not

  13. The Virtual Observatory as a Tool to Study Star Cluster Populations in Starburst Galaxies

    De Grijs, R; Grijs, Richard de; Alvensleben, Uta Fritze-v.

    2002-01-01

    The cluster luminosity function (CLF) is one of the most important diagnostics in the study of old globular and young compact star cluster populations. We are currently using ASTROVIRTEL to obtain CLFs in several optical and/or near-infrared passbands, and colour distributions. This will provide us with a powerful analytical tool for the determination of the violent star and cluster formation history of galaxies: we will address questions related to the universality of the globular CLF, the time-scale of low-mass, low-luminosity star cluster depletion and its observability, and environmental effects affecting the shape of the CLFs and the efficiency of the depletion process. This has required the development of complex data mining tools, which are currently being incorporated in ASTROVIRTEL's "querator".

  14. QUEST FOR COSMOS SUBMILLIMETER GALAXY COUNTERPARTS USING CARMA AND VLA: IDENTIFYING THREE HIGH-REDSHIFT STARBURST GALAXIES

    Smolcic, V. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching b. Muenchen (Germany); Navarrete, F.; Bertoldi, F. [Argelander Institut for Astronomy, Auf dem Huegel 71, Bonn D-53121 (Germany); Aravena, M.; Sheth, K. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Ilbert, O. [Laboratoire d' Astrophysique de Marseille, Universite de Provence, CNRS, BP 8, Traverse du Siphon, F-13376 Marseille Cedex 12 (France); Yun, M. S. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Salvato, M.; Finoguenov, A. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); McCracken, H. J. [Institut d' Astrophysique de Paris, UMR7095 CNRS, Universit Pierre et Marie Curie, 98 bis Boulevard Arago, F-75014 Paris (France); Diener, C. [Institute for Astronomy, ETH Zrich, Wolfgang-Pauli-strasse 27, 8093 Zurich (Switzerland); Aretxaga, I.; Hughes, D.; Wilson, G. [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla, Pue. (Mexico); Riechers, D. A.; Capak, P.; Scoville, N. Z. [Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Karim, A.; Schinnerer, E. [Max Planck Institut fuer Astronomie, Koenigstuhl 17, Heidelberg D-69117 (Germany)

    2012-05-01

    We report on interferometric observations at 1.3 mm at 2''-3'' resolution using the Combined Array for Research in Millimeter-wave Astronomy. We identify multi-wavelength counterparts of three submillimeter galaxies (SMGs; F{sub 1m} > 5.5 mJy) in the COSMOS field, initially detected with MAMBO and AzTEC bolometers at low, {approx}10''-30'', resolution. All three sources-AzTEC/C1, Cosbo-3, and Cosbo-8-are identified to coincide with positions of 20 cm radio sources. Cosbo-3, however, is not associated with the most likely radio counterpart, closest to the MAMBO source position, but with that farther away from it. This illustrates the need for intermediate-resolution ({approx}2'') mm-observations to identify the correct counterparts of single-dish-detected SMGs. All of our three sources become prominent only at NIR wavelengths, and their mm-to-radio flux based redshifts suggest that they lie at redshifts z {approx}> 2. As a proof of concept, we show that photometric redshifts can be well determined for SMGs, and we find photometric redshifts of 5.6 {+-} 1.2, 1.9{sup +0.9}{sub -0.5}, and {approx}4 for AzTEC/C1, Cosbo-3, and Cosbo-8, respectively. Using these we infer that these galaxies have radio-based star formation rates of {approx}> 1000 M{sub Sun} yr{sup -1}and IR luminosities of {approx}10{sup 13} L{sub Sun} consistent with properties of high-redshift SMGs. In summary, our sources reflect a variety of SMG properties in terms of redshift and clustering, consistent with the framework that SMGs are progenitors of z {approx} 2 and today's passive galaxies.

  15. QUEST FOR COSMOS SUBMILLIMETER GALAXY COUNTERPARTS USING CARMA AND VLA: IDENTIFYING THREE HIGH-REDSHIFT STARBURST GALAXIES

    We report on interferometric observations at 1.3 mm at 2''-3'' resolution using the Combined Array for Research in Millimeter-wave Astronomy. We identify multi-wavelength counterparts of three submillimeter galaxies (SMGs; F1m > 5.5 mJy) in the COSMOS field, initially detected with MAMBO and AzTEC bolometers at low, ∼10''-30'', resolution. All three sources—AzTEC/C1, Cosbo-3, and Cosbo-8—are identified to coincide with positions of 20 cm radio sources. Cosbo-3, however, is not associated with the most likely radio counterpart, closest to the MAMBO source position, but with that farther away from it. This illustrates the need for intermediate-resolution (∼2'') mm-observations to identify the correct counterparts of single-dish-detected SMGs. All of our three sources become prominent only at NIR wavelengths, and their mm-to-radio flux based redshifts suggest that they lie at redshifts z ∼> 2. As a proof of concept, we show that photometric redshifts can be well determined for SMGs, and we find photometric redshifts of 5.6 ± 1.2, 1.9+0.9–0.5, and ∼4 for AzTEC/C1, Cosbo-3, and Cosbo-8, respectively. Using these we infer that these galaxies have radio-based star formation rates of ∼> 1000 M☉ yr–1and IR luminosities of ∼1013 L☉ consistent with properties of high-redshift SMGs. In summary, our sources reflect a variety of SMG properties in terms of redshift and clustering, consistent with the framework that SMGs are progenitors of z ∼ 2 and today's passive galaxies.

  16. Cosmic rays and the magnetic field in the nearby starburst galaxy NGC253 III. Helical magnetic fields in the nuclear outflow

    Heesen, Volker; Beck, Rainer; Krause, Marita; Dettmar, Ralf-Jürgen

    2011-01-01

    Magnetic fields are a good tracer for gas compression by shock waves, which can be caused by interaction of star-formation driven outflows from individual star formation sites as described in the chimney model. We study the magnetic field structure in the central part of the nuclear starburst galaxy NGC 253 with spatial resolutions between 40 and 150 pc to detect any filamentary emission associated with the nuclear outflow. New VLA observations at 3 cm with 7.5" resolution were combined with ...

  17. Populations of Bright X-ray Sources in the Starburst Galaxies NGC 4038/4039

    Xi-Wei Liu; Xiang-Dong Li

    2007-01-01

    Assuming a naive star formation history,we construct synthetic X-ray source populations.using a population synthesis code,for comparison with the observed X-ray luminosity function (XLF) of the interacting galaxies NGC 4038/4039.We have included highand intermediate-mass X-ray binaries.young rotation-powered pulsars and fallback disk-fed black holes in modeling the bright X-ray sources detected.We find that the majority of the X-ray sources are likely to be intermediate-mass X-ray binaries.but for typical binary evolution parameters.the predicted XLF seems to be steeper than observed.We note that the shape of the XLFs depends critically on the existence of XLF break for young populations.and suggest super-Eddington accretion luminosities or the existence of intermediate-mass black holes to account for the high luminosity end and the slope of the XLF in NGC 4038/4039.

  18. ALMA imaging of gas and dust in a galaxy protocluster at redshift 5.3: [C II] emission in 'typical' galaxies and dusty starbursts ≈1 billion years after the big bang

    Riechers, Dominik A. [Department of Astronomy, Cornell University, 220 Space Sciences Building, Ithaca, NY 14853 (United States); Carilli, Christopher L. [National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801 (United States); Capak, Peter L.; Yan, Lin [Spitzer Science Center, California Institute of Technology, MC 220-6, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Scoville, Nicholas Z. [Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Smolčić, Vernesa [University of Zagreb, Physics Department, Bijenička cesta 32, 10002 Zagreb (Croatia); Schinnerer, Eva [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Yun, Min [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Cox, Pierre [ALMA Santiago Central Office, Alonso de Cordova 3107, Vitacura, Santiago (Chile); Bertoldi, Frank; Karim, Alexander, E-mail: dr@astro.cornell.edu [Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, Bonn, D-53121 (Germany)

    2014-12-01

    We report interferometric imaging of [C II]({sup 2} P {sub 3/2}→{sup 2} P {sub 1/2}) and OH({sup 2}Π{sub 1/2} J = 3/2→1/2) emission toward the center of the galaxy protocluster associated with the z = 5.3 submillimeter galaxy (SMG) AzTEC-3, using the Atacama Large (sub)Millimeter Array (ALMA). We detect strong [C II], OH, and rest-frame 157.7 μm continuum emission toward the SMG. The [C II]({sup 2} P {sub 3/2}→{sup 2} P {sub 1/2}) emission is distributed over a scale of 3.9 kpc, implying a dynamical mass of 9.7 × 10{sup 10} M {sub ☉}, and a star formation rate (SFR) surface density of Σ{sub SFR} = 530 M {sub ☉} yr{sup –1} kpc{sup –2}. This suggests that AzTEC-3 forms stars at Σ{sub SFR} approaching the Eddington limit for radiation pressure supported disks. We find that the OH emission is slightly blueshifted relative to the [C II] line, which may indicate a molecular outflow associated with the peak phase of the starburst. We also detect and dynamically resolve [C II]({sup 2} P {sub 3/2}→{sup 2} P {sub 1/2}) emission over a scale of 7.5 kpc toward a triplet of Lyman-break galaxies with moderate UV-based SFRs in the protocluster at ∼95 kpc projected distance from the SMG. These galaxies are not detected in the continuum, suggesting far-infrared SFRs of <18-54 M {sub ☉} yr{sup –1}, consistent with a UV-based estimate of 22 M {sub ☉} yr{sup –1}. The spectral energy distribution of these galaxies is inconsistent with nearby spiral and starburst galaxies, but resembles those of dwarf galaxies. This is consistent with expectations for young starbursts without significant older stellar populations. This suggests that these galaxies are significantly metal-enriched, but not heavily dust-obscured, 'normal' star-forming galaxies at z > 5, showing that ALMA can detect the interstellar medium in 'typical' galaxies in the very early universe.

  19. Quest for COSMOS submillimeter galaxy counterparts using CARMA and VLA: Identifying three high-redshift starburst galaxies

    Smolcic, V; Aravena, M; Ilbert, O; Yun, M S; Sheth, K; Salvato, M; McCracken, H J; Diener, C; Aretxaga, I; Riechers, D A; Finoguenov, A; Bertoldi, F; Capak, P; Hughes, D; Karim, A; Schinnerer, E; Scoville, N Z; Wilson, G

    2012-01-01

    We report on interferometric observations at 1.3 mm at 2"-3" resolution using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We identify multi-wavelength counterparts of three submillimeter galaxies (SMGs; F(1mm)>5.5 mJy) in the COSMOS field, initially detected with MAMBO and AzTEC bolometers at low, ~10"-30", resolution. All three sources -- AzTEC/C1, Cosbo-3 and Cosbo-8 -- are identified to coincide with positions of 20 cm radio sources. Cosbo-3, however, is not associated with the most likely radio counterpart, closest to the MAMBO source position, but that further away from it. This illustrates the need for intermediate-resolution (~2") mm-observations to identify the correct counterparts of single-dish detected SMGs. All of our three sources become prominent only at NIR wavelengths, and their mm-to-radio flux based redshifts suggest that they lie at redshifts z>~2. As a proof of concept, we show that photometric redshifts can be well determined for SMGs, and we find photometric-red...

  20. The kiloparsec-scale star formation law at redshift 4: wide-spread, highly efficient star formation in the dust-obscured starburst galaxy GN20

    Hodge, J A; Decarli, R; Walter, F; Carilli, C L; Daddi, E; Dannerbauer, H

    2014-01-01

    We present high-resolution observations of the 880 $\\mu$m (rest-frame FIR) continuum emission in the z$=$4.05 submillimeter galaxy GN20 from the IRAM Plateau de Bure Interferometer (PdBI). These data resolve the obscured star formation in this unlensed galaxy on scales of 0.3$^{\\prime\\prime}$$\\times$0.2$^{\\prime\\prime}$ ($\\sim$2.1$\\times$1.3 kpc). The observations reveal a bright (16$\\pm$1 mJy) dusty starburst centered on the cold molecular gas reservoir and showing a bar-like extension along the major axis. The striking anti-correlation with the HST/WFC3 imaging suggests that the copious dust surrounding the starburst heavily obscures the rest-frame UV/optical emission. A comparison with 1.2 mm PdBI continuum data reveals no evidence for variations in the dust properties across the source within the uncertainties, consistent with extended star formation, and the peak star formation rate surface density (119$\\pm$8 M$_{\\odot}$ yr$^{-1}$ kpc$^{-2}$) implies that the star formation in GN20 remains sub-Eddington ...

  1. The spatially resolved dynamics of dusty starburst galaxies in a z ˜ 0.4 cluster: beginning the transition from spirals to S0s

    Johnson, H. L.; Harrison, C. M.; Swinbank, A. M.; Bower, R. G.; Smail, Ian; Koyama, Y.; Geach, J. E.

    2016-07-01

    To investigate what drives the reversal of the morphology-density relation at intermediate/high redshift, we present a multiwavelength analysis of 27 dusty starburst galaxies in the massive cluster Cl 0024+17 at z = 0.4. We combine Hα dynamical maps from the VLT/FLAMES multi-IFU system with far-infrared imaging using Herschel/SPIRE and millimetre spectroscopy from IRAM/NOEMA, in order to measure the dynamics, star formation rates and gas masses of this sample. Most galaxies appear to be rotationally supported, with a median ratio of rotational-support to line-of-sight velocity dispersion v/σ ˜ 5 ± 2, and specific angular momentum λR = 0.83 ± 0.06 - comparable to field spirals of a similar mass at this redshift. The star formation rates of 3-26 M⊙ yr-1 and average 12CO-derived gas mass of ˜ 1 × 1010 M⊙ suggest gas depletion time-scales of ˜1 Gyr (˜0.25 of the cluster crossing time). We derive characteristic dust temperatures (mean Td = 26 ± 1 K) consistent with local galaxies of similar far-infrared luminosity, suggesting that the low-density gas is yet to be stripped. Taken together, these results suggest that these starbursts have only recently accreted from the field, with star formation rates likely enhanced due to the effects of ram pressure. In order to make the transition to cluster S0s these galaxies must lose ˜40 per cent of their specific angular momentum. We suggest this must occur ≥1 Gyr later, after the molecular gas has been depleted and/or stripped, via multiple tidal interactions with other cluster members.

  2. The Spatially Resolved Dynamics of Dusty Starburst Galaxies in a z ˜ 0.4 Cluster: Beginning the Transition from Spirals to S0s

    Johnson, H. L.; Harrison, C. M.; Swinbank, A. M.; Bower, R. G.; Smail, Ian; Koyama, Y.; Geach, J. E.

    2016-05-01

    To investigate what drives the reversal of the morphology-density relation at intermediate/high redshift, we present a multi-wavelength analysis of 27 dusty starburst galaxies in the massive cluster Cl 0024+17 at z = 0.4. We combine Hα dynamical maps from the VLT / FLAMES multi-IFU system with far-infrared imaging using Herschel / SPIRE and millimeter spectroscopy from IRAM / NOEMA, in order to measure the dynamics, star formation rates and gas masses of this sample. Most galaxies appear to be rotationally supported, with a median ratio of rotational-support to line-of-sight velocity dispersion v/σ ˜ 5 ± 2, and specific angular momentum λR = 0.83 ± 0.06 - comparable to field spirals of a similar mass at this redshift. The star formation rates of 3-26 M⊙ yr-1 and average 12CO-derived gas mass of ˜ 1 × 1010 M⊙ suggest gas depletion timescales of ˜ 1 Gyr (˜ 0.25 of the cluster crossing time). We derive characteristic dust temperatures (mean Td = 26 ± 1 K) consistent with local galaxies of similar far-infrared luminosity, suggesting that the low density gas is yet to be stripped. Taken together, these results suggest that these starbursts have only recently accreted from the field, with star formation rates likely enhanced due to the effects of ram pressure. In order to make the transition to cluster S0s these galaxies must lose ˜ 40% of their specific angular momentum. We suggest this must occur ≥ 1 Gyr later, after the molecular gas has been depleted and/or stripped, via multiple tidal interactions with other cluster members.

  3. The State of the Warm and Cold Gas in the Extreme Starburst at the Core of the Phoenix Galaxy Cluster (SPT-CLJ2344-4243)

    McDonald, Michael; Edge, Alastair C; Wilner, David J; Veilleux, Sylvain; Benson, Braford A; Hogan, Michael T; Marrone, Daniel P; McNamara, Brian R; Wei, Lisa H; Bayliss, Matthew B; Bautz, Marshall W

    2013-01-01

    [Abridged] We present new optical integral field spectroscopy (Gemini South) and submillimeter spectroscopy (Submillimeter Array) of the central galaxy in the Phoenix cluster (SPT-CLJ2344-4243). This cluster was previously reported to have a massive starburst (~800 Msun/yr) in the central, brightest cluster galaxy, most likely fueled by the rapidly-cooling intracluster medium. These new data reveal a complex emission-line nebula, extending for >30 kpc from the central galaxy. The total Halpha luminosity, assuming Halpha/Hbeta = 2.85, is L_Ha = 7.6 +/- 0.4 x10^43 erg/s, making this the most luminous emission line nebula detected in the center of a cool core cluster. Overall, the relative fluxes of the low-ionization lines (e.g., [O II], Hbeta) to the UV continuum are consistent with photoionization by young stars. In both the center of the galaxy and in a newly-discovered highly-ionized plume to the north of the galaxy, the ionization ratios are consistent with both shocks and AGN photoionization. We speculate...

  4. Spatially Resolving a Starburst Galaxy at Hard X-ray Energies: NuSTAR, Chandra, AND VLBA Observations of NGC 253

    Wik, Daniel R; Hornschemeier, Ann E; Yukita, Mihoko; Ptak, Andrew; Zezas, Andreas; Antoniou, Vallia; Argo, Megan K; Bechtol, Keith; Boggs, Steven; Christensen, Finn; Craig, William; Hailey, Charles; Harrison, Fiona; Krivanos, Roman; Maccarone, Thomas J; Stern, Daniel; Venters, Tonia; Zhang, William W

    2014-01-01

    Prior to the launch of NuSTAR, it was not feasible to spatially resolve the hard (E > 10 keV) emission from galaxies beyond the Local Group. The combined NuSTAR dataset, comprised of three ~165 ks observations, allows spatial characterization of the hard X-ray emission in the galaxy NGC 253 for the first time. As a follow up to our initial study of its nuclear region, we present the first results concerning the full galaxy from simultaneous NuSTAR, Chandra, and VLBA monitoring of the local starburst galaxy NGC 253. Above ~10 keV, nearly all the emission is concentrated within 100" of the galactic center, produced almost exclusively by three nuclear sources, an off-nuclear ultraluminous X-ray source (ULX), and a pulsar candidate that we identify for the first time in these observations. We detect 21 distinct sources in energy bands up to 25 keV, mostly consisting of intermediate state black hole X-ray binaries. The global X-ray emission of the galaxy - dominated by the off-nuclear ULX and nuclear sources, whic...

  5. THE KILOPARSEC-SCALE STAR FORMATION LAW AT REDSHIFT 4: WIDESPREAD, HIGHLY EFFICIENT STAR FORMATION IN THE DUST-OBSCURED STARBURST GALAXY GN20

    We present high-resolution observations of the 880 μm (rest-frame FIR) continuum emission in the z = 4.05 submillimeter galaxy GN20 from the IRAM Plateau de Bure Interferometer (PdBI). These data resolve the obscured star formation (SF) in this unlensed galaxy on scales of 0.''3 × 0.''2 (∼2.1 × 1.3 kpc). The observations reveal a bright (16 ± 1 mJy) dusty starburst centered on the cold molecular gas reservoir and showing a bar-like extension along the major axis. The striking anti-correlation with the Hubble Space Telescope/Wide Field Camera 3 imaging suggests that the copious dust surrounding the starburst heavily obscures the rest-frame UV/optical emission. A comparison with 1.2 mm PdBI continuum data reveals no evidence for variations in the dust properties across the source within the uncertainties, consistent with extended SF, and the peak star formation rate surface density (119 ± 8 M ☉ yr–1 kpc–2) implies that the SF in GN20 remains sub-Eddington on scales down to 3 kpc2. We find that the SF efficiency (SFE) is highest in the central regions of GN20, leading to a resolved SF law with a power-law slope of ΣSFR ∼ ΣH22.1±1.0, and that GN20 lies above the sequence of normal star-forming disks, implying that the dispersion in the SF law is not due solely to morphology or choice of conversion factor. These data extend previous evidence for a fixed SFE per free-fall time to include the star-forming medium on ∼kiloparsec scales in a galaxy 12 Gyr ago

  6. HerMES: The Rest-Frame UV Emission and A Lensing Model for the z=6.34 Luminous Dusty Starburst Galaxy HFLS3

    Cooray, Asantha; Wardlow, Julie L; Bock, J; Bridge, C; Burgarella, D; Bussmann, R S; Casey, C M; Clements, D; Conley, A; Farrah, D; Fu, H; Gavazzi, R; Ivison, R J; Laporte, N; Lofaro, B; Ma, Brian; Magdis, G; Oliver, S J; Osage, W A; Pe'rez-Fournon, I; Riechers, D; Rigopoulou, D; Scott, D; Viero, M; Watson, D

    2014-01-01

    We discuss the restframe UV emission from the starbursting galaxy HFLS3 at z=6.34, discovered in Herschel/SPIRE data due to its red color in the submm wavelengths from 250-500 um. The apparent inst. SFR of HFLS3 inferred from the total FIR luminosity measured with over 15 photometric data points between 100 to 1000 um is 2900 Msun/yr. Keck/NIRC2 Ks band adaptive optics imaging data showed two potential NIR counterparts near HFLS3. Previously, the northern galaxy was taken to be in the foreground at z=2.1 while the southern galaxy was assumed to HFLS3's NIR counterpart. New HST/WFC3 and ACS imaging data show both optically bright galaxies are in the foreground at z<6. A new lensing model based on HST data and mm-wave continuum emission yields a magnification of 2.2+/-0.3. The lack of multiple imaging constrains the lensing magnification to be lower than either 2.7 or 3.5 at the 95% confidence level for the two scenarios, which attribute one or two components to HFLS3 in the source plane. Correcting for grav...

  7. HerMES: The Rest-frame UV Emission and a Lensing Model for the z = 6.34 Luminous Dusty Starburst Galaxy HFLS3

    Cooray, Asantha; Calanog, Jae; Wardlow, Julie L.; Bock, J.; Bridge, C.; Burgarella, D.; Bussmann, R. S.; Casey, C. M.; Clements, D.; Conley, A.; Farrah, D.; Fu, H.; Gavazzi, R.; Ivison, R. J.; La Porte, N.; Lo Faro, B.; Ma, Brian; Magdis, G.; Oliver, S. J.; Osage, W. A.; Pérez-Fournon, I.; Riechers, D.; Rigopoulou, D.; Scott, Douglas; Viero, M.; Watson, D.

    2014-07-01

    We discuss the rest-frame ultraviolet emission from the starbursting galaxy HFLS3 at a redshift of 6.34. The galaxy was discovered in Herschel/SPIRE data due to its red color in the submillimeter wavelengths from 250 to 500 μm. Keck/NIRC2 K s -band adaptive optics imaging data showed two potential near-IR counterparts near HFLS3. Previously, the northern galaxy was taken to be in the foreground at z = 2.1, while the southern galaxy was assumed to be HFLS3's near-IR counterpart. The recently acquired Hubble/WFC3 and Advanced Camera for Surveys (ACS) imaging data show conclusively that both optically bright galaxies are in the foreground at z < 6. A new lensing model based on the Hubble imaging data and the millimeter-wave continuum emission yields a magnification factor of 2.2 ± 0.3, with a 95% confidence upper limit on the magnification of 3.5. When corrected for lensing, the instantaneous star formation rate is 1320 M ⊙ yr-1, with the 95% confidence lower limit around 830 M ⊙ yr-1. The dust and stellar masses of HFLS3 from the same spectral energy distribution (SED) models are at the level of 3 × 108 M ⊙ and ~5 × 1010 M ⊙, respectively, with large systematic uncertainties on assumptions related to the SED model. With Hubble/WFC3 images, we also find diffuse near-IR emission about 0.5 arcsec (~3 kpc) to the southwest of HFLS3 that remains undetected in the ACS imaging data. The emission has a photometric redshift consistent with either z ~ 6 or a dusty galaxy template at z ~ 2.

  8. HerMES: The rest-frame UV emission and a lensing model for the z = 6.34 luminous dusty starburst galaxy HFLS3

    Cooray, Asantha; Calanog, Jae; Casey, C. M.; Ma, Brian; Osage, W. A. [Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Wardlow, Julie L. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Bock, J.; Bridge, C. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Burgarella, D. [Laboratoire d' Astrophysique de Marseille, Aix-Marseille University, CNRS, F-13013 Marseille (France); Bussmann, R. S. [Department of Astronomy, Space Science Building, Cornell University, Ithaca, NY 14853-6801 (United States); Clements, D. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Conley, A. [Department of Astrophysical and Planetary Sciences, CASA 389-UCB, University of Colorado, Boulder, CO 80309 (United States); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Fu, H. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Gavazzi, R. [Institut d' Astrophysique de Paris, UMR 7095, CNRS, UPMC Univ. Paris 06, 98bis boulevard Arago, F-75014 Paris (France); Ivison, R. J. [European Southern Observatory, Karl Schwarzschild Strasse 2, D-85748 Garching (Germany); La Porte, N. [Pontificia Universidad Caólica de Chile, Departamento de Astronomía y Astrofísica, Casilla 306, Santiago 22 (Chile); Lo Faro, B. [Aix-Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR7326, F-13388 Marseille (France); Magdis, G. [Department of Astrophysics, Denys Wilkinson Building, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Oliver, S. J. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); and others

    2014-07-20

    We discuss the rest-frame ultraviolet emission from the starbursting galaxy HFLS3 at a redshift of 6.34. The galaxy was discovered in Herschel/SPIRE data due to its red color in the submillimeter wavelengths from 250 to 500 μm. Keck/NIRC2 K{sub s}-band adaptive optics imaging data showed two potential near-IR counterparts near HFLS3. Previously, the northern galaxy was taken to be in the foreground at z = 2.1, while the southern galaxy was assumed to be HFLS3's near-IR counterpart. The recently acquired Hubble/WFC3 and Advanced Camera for Surveys (ACS) imaging data show conclusively that both optically bright galaxies are in the foreground at z < 6. A new lensing model based on the Hubble imaging data and the millimeter-wave continuum emission yields a magnification factor of 2.2 ± 0.3, with a 95% confidence upper limit on the magnification of 3.5. When corrected for lensing, the instantaneous star formation rate is 1320 M{sub ☉} yr{sup –1}, with the 95% confidence lower limit around 830 M{sub ☉} yr{sup –1}. The dust and stellar masses of HFLS3 from the same spectral energy distribution (SED) models are at the level of 3 × 10{sup 8} M{sub ☉} and ∼5 × 10{sup 10} M{sub ☉}, respectively, with large systematic uncertainties on assumptions related to the SED model. With Hubble/WFC3 images, we also find diffuse near-IR emission about 0.5 arcsec (∼3 kpc) to the southwest of HFLS3 that remains undetected in the ACS imaging data. The emission has a photometric redshift consistent with either z ∼ 6 or a dusty galaxy template at z ∼ 2.

  9. The Optical Structure of the Starburst Galaxy M82. II. Nebular Properties of the Disk and Inner-Wind

    Westmoquette, M S; Smith, L J; Trancho, G; Bastian, N; Konstantopoulos, I S

    2009-01-01

    (Abridged) In this second paper of the series, we present the results from optical Gemini-North GMOS-IFU and WIYN DensePak IFU spectroscopic observations of the starburst and inner wind zones of M82, with a focus on the state of the T~10^4 K ionized interstellar medium. Our electron density maps show peaks of a few 1000 cm-3, local small spatial-scale variations, and a fall-off in the minor axis direction. We discuss the implications of these results with regards to the conditions/locations that may favour the escape of individual cluster winds. Our findings imply that the starburst environment is highly fragmented into a range of clouds from small/dense clumps with low filling factors (10^4 cm-3) to larger filling factor, less dense gas. The near-constant state of the ionization state of the ~10^4 K gas throughout the starburst can be explained as a consequence of the small cloud sizes, which allow the gas conditions to respond quickly to any changes. We have examined in more detail both the broad (FWHM 150-...

  10. Spatially resolving a starburst galaxy at hard X-ray energies: NuSTAR, CHANDRA, AND VLBA observations of NGC 253

    Wik, D. R.; Lehmer, B. D.; Hornschemeier, A. E.;

    2014-01-01

    intermediate state black hole X-ray binaries. The global X-ray emission of the galaxy-dominated by the off-nuclear ULX and nuclear sources, which are also likely ULXs-falls steeply (photon index ≳ 3) above 10 keV, consistent with other NuSTAR-observed ULXs, and no significant excess above the background is...... the first time. As a follow up to our initial study of its nuclear region, we present the first results concerning the full galaxy from simultaneous NuSTAR, Chandra, and Very Long Baseline Array monitoring of the local starburst galaxy NGC 253. Above ~10 keV, nearly all the emission is concentrated...... within 100" of the galactic center, produced almost exclusively by three nuclear sources, an off-nuclear ultraluminous X-ray source (ULX), and a pulsar candidate that we identify for the first time in these observations. We detect 21 distinct sources in energy bands up to 25 keV, mostly consisting of...

  11. The Spatially Resolved Dynamics of Dusty Starburst Galaxies in a z ~ 0.4 Cluster: Beginning the Transition from Spirals to S0s

    Johnson, H L; Swinbank, A M; Bower, R G; Smail, Ian; Koyama, Y; Geach, J E

    2016-01-01

    To investigate what drives the reversal of the morphology-density relation at intermediate/high redshift, we present a multi-wavelength analysis of 27 dusty starburst galaxies in the massive cluster Cl 0024+17 at z = 0.4. We combine H-alpha dynamical maps from the VLT/FLAMES multi-IFU system with far-infrared imaging using Herschel SPIRE and millimetre spectroscopy from IRAM/NOEMA, in order to measure the dynamics, star formation rates and gas masses of this sample. Most galaxies appear to be rotationally supported, with a median ratio of rotational support to line-of-sight velocity dispersion v/sigma ~ 5 +/- 2, and specific angular momentum lambda_R = 0.83 +/- 0.06 - comparable to field spirals of a similar mass at this redshift. The star formation rates of 3 - 26 M_solar/yr and average 12 CO derived gas mass of 1 x 10^10 M_solar suggest gas depletion timescales of ~ 1Gyr (~ 0.25 of the cluster crossing time). We derive characteristic dust temperatures (mean T_dust = 26 +/- 1 K) consistent with local galaxie...

  12. X-ray observations of the starburst galaxy NGC 253 --- II. Extended emission from hot gas in the nuclear area, disk, and halo

    Pietsch, W.; Vogler, A.; Klein, U.; Zinnecker, H.

    2000-08-01

    Spatial and spectral analysis of deep ROSAT HRI and PSPC observations of the near edge-on starburst galaxy NGC 253 reveal diffuse soft X-ray emission, which contributes 80% to its total X-ray luminosity (LX = 5 1039 erg s-1, corrected for foreground absorption). The nuclear area, disk, and halo contribution to the luminosity is about equal. The starburst nucleus itself is highly absorbed and not visible in the ROSAT band. The emission from the nuclear area stems from a heavily absorbed source with an extent of 250 pc (FWHM) about 100 pc above the nucleus along the SE minor axis ("nuclear source", X34), and the "X-ray plume". The nuclear source is best described as having a thermal bremsstrahlung spectrum with a temperature of T = 1.2 keV (NH = 3 1021 cm-2) and LXexgal = 3 1038 erg s-1 (corrected for Galactic foreground absorption). The spectrum of the hollow-cone shaped plume (opening angle of 32̂ and extent of ~ 700 pc along the SE minor axis) is best modeled by a composite of a thermal bremsstrahlung (NH = 3 1020 cm-2, T = 1.2 keV, LXexgal = 4.6 1038 erg s-1) and a thin thermal plasma (Galactic foreground absorption, T = 0.33 keV, LXexgal = 4 1038 erg s-1). The diffuse nuclear emission components trace interactions between the galactic super-wind emitted by the starburst nucleus, and the dense interstellar medium of the disk. Diffuse emission from the disk is heavily absorbed and follows the spiral structure. It can be described by a thin thermal plasma spectrum (T = 0.7 keV, intrinsic luminosity LXintr = 1.2 1039 erg s-1), and most likely reflects a mixture of sources (X-ray binaries, supernova remnants, and emission from H II regions) and the hot interstellar medium. The surface brightness profile reveals a bright inner and a fainter outer component along the major axis with extents of ∓3.4 kpc and ∓7.5 kpc. We analysed the total halo emission separated into two geometrical areas; the "corona" (scale height ~ 1 kpc) and the "outer halo". The coronal

  13. The Sloan Digital Sky Survey Reverberation Mapping Project: Post-Starburst Signatures in Quasar Host Galaxies at z < 1

    Matsuoka, Yoshiki; Shen, Yue; Brandt, William N; Greene, Jenny E; Ho, Luis C; Schneider, Donald P; Sun, Mouyuan; Trump, Jonathan R

    2015-01-01

    Quasar host galaxies are key for understanding the relation between galaxies and the supermassive black holes (SMBHs) at their cores. We present a study of 191 unobscured quasars and their host galaxies at z < 1, using high signal-to-noise ratio (SNR) spectra produced by the Sloan Digital Sky Survey Reverberation Mapping project. Clear detection of stellar absorption lines allows a reliable decomposition of the observed spectra into nuclear and host components, using spectral models of quasar and stellar radiations as well as emission lines from the interstellar medium. We estimate age, mass (M*), and velocity dispersion (sigma*) of the host stars, the star formation rate (SFR), quasar luminosity, and SMBH mass (Mbh), for each object. The quasars are preferentially hosted by massive galaxies with M* ~ 10^{11} Msun characterized by stellar ages around a billion years, which coincides with the transition phase of normal galaxies from the blue cloud to the red sequence. The host galaxies have relatively low S...

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

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

    2011-01-01

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

  15. O VI Emission Imaging of a Galaxy with the Hubble Space Telescope: a Warm Gas Halo Surrounding the Intense Starburst SDSS J115630.63+500822.1

    Hayes, Matthew; Östlin, Göran; Scarlata, Claudia; Lehnert, Matthew D; Mannerström-Jansson, Gustav

    2016-01-01

    We report results from a new HST study of the OVI 1032,1038\\AA\\ doublet in emission around intensely star-forming galaxies. The programme aims to characterize the energy balance in starburst galaxies and gas cooling in the difficult-to-map coronal temperature regime of 2-5 x $10^5$K. We present the first resolved image of gas emission in the OVI line. Our target, SDSS J1156+5008, is very compact in the continuum but displays OVI emission to radii of 23 kpc. The surface brightness profile is well fit by an exponential with a scale of 7.5kpc. This is ten times the size of the photoionized gas, and we estimate that 1/6 the total OVI luminosity comes from resonantly scattered continuum radiation. Spectroscopy - which closely resembles a stacked sample of archival spectra - confirms the OVI emission, and determines the column density and outflow velocity from blueshifted absorption. The combination of measurements enables several new calculations with few assumptions. The OVI regions fill only ~$10^{-3}$ of the vo...

  16. The optical structure of the starburst galaxy M82 - I: Dynamics of the disk and inner-wind

    Westmoquette, M S; Gallagher, J S; Trancho, G; Bastian, N; Konstantopoulos, I S

    2009-01-01

    [Abridged] We present Gemini-N GMOS-IFU observations of the central starburst clumps and inner wind of M82, together with WIYN DensePak IFU observations of the inner 2x0.9kpc of the disk. These cover the emission lines of H$\\alpha$, [NII], [SII], and [SIII]. We were able to accurately decompose the emission line profiles into multiple narrow components (FWHM~30-130kms) superimposed on a broad (FWHM 150-350kms) feature. This paper is the first of a series examining the optical structure of M82's disk and inner wind; here we focus on the ionized gaseous and stellar dynamics and present maps of the relevant emission line properties. Our observations show that ionized gas in the starburst core of M82 is dynamically complex. Localised line splitting of up to 100kms in the narrow component is associated with expanding shells of compressed, cool, photoionized gas. We have been able to associate some of this inner-wind gas with a distinct outflow channel characterised by its dynamics and gas density patterns, and we ...

  17. The Optical Structure of the Starburst Galaxy M82. II. Nebular Properties of the Disk and Inner Wind

    Westmoquette, M. S.; Gallagher, J. S.; Smith, L. J.; Trancho, G.; Bastian, N.; Konstantopoulos, I. S.

    2009-12-01

    In this second paper of the series, we present the results from optical Gemini-North GMOS-IFU and WIYN DensePak IFU spectroscopic observations of the starburst and inner wind zones of M82, with a focus on the state of the T ~ 104 K ionized interstellar medium. Our electron density maps show peaks of a few 1000 cm-3 (implying very high thermal pressures), local small spatial-scale variations, and a falloff in the minor axis direction. We discuss the implications of these results with regards to the conditions/locations that may favor the escape of individual cluster winds that ultimately power the large-scale superwind. Our findings, when combined with the body of literature built up over the last decade on the state of the interstellar medium (ISM) in M82, imply that the starburst environment is highly fragmented into a range of clouds from small/dense clumps with low-filling factors (cluster complexes, whereas the cloud sizes in the inter-complex region are larger. These dense clouds are bathed with an intense radiation field and embedded in an extensive high temperature (T gsim 106 K), X-ray-emitting ISM that is a product of the high star formation rates in the starburst zones of M82. The near-constant state of the ionization state of the ~104 K gas throughout the M82 starburst zone can be explained as a consequence of the small cloud sizes, which allow the gas conditions to respond quickly to any changes. In Paper I, we found that the observed emission lines are composed of multiple components, including a broad (FWHM ~ 150-350 km s-1) feature that we associate with emission from turbulent mixing layers on the surfaces of the gas clouds, resulting from the interaction of the fast wind outflows from the synchrotron self-Comptons. The large number of compact clouds and wind sources provides an ideal environment for broad line emission, and explains the large observed broad/narrow-line flux ratios. We have examined in more detail the discrete outflow channel

  18. THE OPTICAL STRUCTURE OF THE STARBURST GALAXY M82. II. NEBULAR PROPERTIES OF THE DISK AND INNER WIND

    In this second paper of the series, we present the results from optical Gemini-North GMOS-IFU and WIYN DensePak IFU spectroscopic observations of the starburst and inner wind zones of M82, with a focus on the state of the T ∼ 104 K ionized interstellar medium. Our electron density maps show peaks of a few 1000 cm-3 (implying very high thermal pressures), local small spatial-scale variations, and a falloff in the minor axis direction. We discuss the implications of these results with regards to the conditions/locations that may favor the escape of individual cluster winds that ultimately power the large-scale superwind. Our findings, when combined with the body of literature built up over the last decade on the state of the interstellar medium (ISM) in M82, imply that the starburst environment is highly fragmented into a range of clouds from small/dense clumps with low-filling factors (e ∼> 104 cm-3) to larger filling factor, less dense gas. The most compact clouds seem to be found in the cores of the star cluster complexes, whereas the cloud sizes in the inter-complex region are larger. These dense clouds are bathed with an intense radiation field and embedded in an extensive high temperature (T ∼> 106 K), X-ray-emitting ISM that is a product of the high star formation rates in the starburst zones of M82. The near-constant state of the ionization state of the ∼104 K gas throughout the M82 starburst zone can be explained as a consequence of the small cloud sizes, which allow the gas conditions to respond quickly to any changes. In Paper I, we found that the observed emission lines are composed of multiple components, including a broad (FWHM ∼ 150-350 km s-1) feature that we associate with emission from turbulent mixing layers on the surfaces of the gas clouds, resulting from the interaction of the fast wind outflows from the synchrotron self-Comptons. The large number of compact clouds and wind sources provides an ideal environment for broad line emission

  19. Extreme Starbursts in the Local Universe

    Delgado, R M Gonzalez; Perez, E; Alonso-Herrero, A; Tadhunter, C; Veilleux, S; Heckman, T; Overzier, R; Goncalves, T S; Alberdi, A; Torres, M A Perez; Pasquali, A; Monreal-Ibero, A; Diaz-Santos, T; Garcia-Burillo, S; Caballero, D Miralles; Di Matteo, P; Kewley, L; Almeida, C Ramos; Weiner, B; Rothberg, B; Tan, J C; Jogee, S; Fernandes, R Cid; Rodrigues, M; Delgado-Serrano, R; Spoon, H; Hopkins, P; Rupke, D; Bellocchi, E; Cortijo, C; Lopez, J Piqueras; Canalizo, G; Imanishi, M; Lazarova, M; Villar-Martin, M; Brotherton, M; Wild, V; Swinbank, M; Menendez-Delmestre, K; Hammer, F; Perez-Gonz?alez, P; Turner, J; Fischer, J; Sanchez, S F; Colina, L; Gardini, A

    2010-01-01

    The "Extreme starbursts in the local universe" workshop was held at the Insituto de Astrofisica de Andalucia in Granada, Spain on 21-25 June 2010. Bearing in mind the advent of a new generation of facilities such as JWST, Herschel, ALMA, eVLA and eMerlin, the aim of the workshop was to bring together observers and theorists to review the latest results. The purpose of the workshop was to address the following issues: what are the main modes of triggering extreme starbursts in the local Universe? How efficiently are stars formed in extreme starbursts? What are the star formation histories of local starburst galaxies? How well do the theoretical simulations model the observations? What can we learn about starbursts in the distant Universe through studies of their local counterparts? How important is the role of extreme starbursts in the hierarchical assembly of galaxies? How are extreme starbursts related to the triggering of AGN in the nuclei of galaxies? Overall, 41 talks and 4 posters with their correspondin...

  20. THE M81 GROUP DWARF IRREGULAR GALAXY DDO 165. I. HIGH-VELOCITY NEUTRAL GAS IN A POST-STARBURST SYSTEM

    We present new multi-configuration Very Large Array H I spectral line observations of the M81 group dwarf irregular post-starburst galaxy DDO 165. The H I morphology is complex, with multiple column density peaks surrounding a large region of very low H I surface density that is offset from the center of the stellar distribution. The bulk of the neutral gas is associated with the southern section of the galaxy; a secondary peak in the north contains ∼15% of the total H I mass. These components appear to be kinematically distinct, suggesting that either tidal processes or large-scale blowout have recently shaped the interstellar medium (ISM) of DDO 165. Using spatially resolved position-velocity maps, we find multiple localized high-velocity gas features. Cross-correlating with radius-velocity analyses, we identify eight shell/hole structures in the ISM with a range of sizes (∼400-900 pc) and expansion velocities (∼7-11 km s-1). These structures are compared with narrow- and broadband imaging from the Kitt Peak National Observatory and the Hubble Space Telescope (HST). Using the latter data, recent works have shown that DDO 165's previous 'burst' phase was extended temporally (∼>1 Gyr). We thus interpret the high-velocity gas features, H I holes, and kinematically distinct components of the galaxy in the context of the immediate effects of 'feedback' from recent star formation (SF). In addition to creating H I holes and shells, extended SF events are capable of creating localized high-velocity motion of the surrounding interstellar material. A companion paper connects the energetics from the H I and HST data.

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

    Kepley, Amanda A.; Leroy, Adam K.; Frayer, David; Usero, Antonio; Marvil, Josh; Walter, Fabian

    2013-01-01

    Observations of the Milky Way and nearby galaxies show that dense molecular gas correlates with recent star formation, suggesting that the formation of this gas phase may help regulate star formation. A key test of this idea requires wide-area, high-resolution maps of dense molecular gas in galaxies to explore how local physical conditions drive dense gas formation, but these observations have been limited because of the faintness of dense gas tracers like HCN and HCO+. Here we demonstrate th...

  2. Highest Redshift Image of Neutral Hydrogen in Emission: A CHILES Detection of a Starbursting Galaxy at z = 0.376

    Fernández, Ximena; Gim, Hansung B.; van Gorkom, J. H.; Yun, Min S.; Momjian, Emmanuel; Popping, Attila; Chomiuk, Laura; Hess, Kelley M.; Hunt, Lucas; Kreckel, Kathryn; Lucero, Danielle; Maddox, Natasha; Oosterloo, Tom; Pisano, D. J.; Verheijen, M. A. W.; Hales, Christopher A.; Chung, Aeree; Dodson, Richard; Golap, Kumar; Gross, Julia; Henning, Patricia; Hibbard, John; Jaffé, Yara L.; Donovan Meyer, Jennifer; Meyer, Martin; Sanchez-Barrantes, Monica; Schiminovich, David; Wicenec, Andreas; Wilcots, Eric; Bershady, Matthew; Scoville, Nick; Strader, Jay; Tremou, Evangelia; Salinas, Ricardo; Chávez, Ricardo

    2016-06-01

    Our current understanding of galaxy evolution still has many uncertainties associated with the details of the accretion, processing, and removal of gas across cosmic time. The next generation of radio telescopes will image the neutral hydrogen (H i) in galaxies over large volumes at high redshifts, which will provide key insights into these processes. We are conducting the COSMOS H i Large Extragalactic Survey (CHILES) with the Karl G. Jansky Very Large Array, which is the first survey to simultaneously observe H i from z = 0 to z ∼ 0.5. Here, we report the highest redshift H i 21 cm detection in emission to date of the luminous infrared galaxy COSMOS J100054.83+023126.2 at z = 0.376 with the first 178 hr of CHILES data. The total H i mass is (2.9 ± 1.0) × 1010 M ⊙ and the spatial distribution is asymmetric and extends beyond the galaxy. While optically the galaxy looks undisturbed, the H i distribution suggests an interaction with a candidate companion. In addition, we present follow-up Large Millimeter Telescope CO observations that show it is rich in molecular hydrogen, with a range of possible masses of (1.8–9.9) × 1010 M ⊙. This is the first study of the H i and CO in emission for a single galaxy beyond z ∼ 0.2.

  3. THE ACS NEARBY GALAXY SURVEY TREASURY. VII. THE NGC 4214 STARBURST AND THE EFFECTS OF STAR FORMATION HISTORY ON DWARF MORPHOLOGY

    We present deep Hubble Space Telescope WFPC2 optical observations obtained as part of the ACS Nearby Galaxy Survey Treasury as well as early release Wide Field Camera 3 ultraviolet and infrared observations of the nearby dwarf starbursting galaxy NGC 4214. Our data provide a detailed example of how covering such a broad range in wavelength provides a powerful tool for constraining the physical properties of stellar populations. The deepest data reach the ancient red clump at MF814W ∼ - 0.2. All of the optical data reach the main-sequence turnoff for stars younger than ∼300 Myr and the blue He-burning sequence for stars younger than 500 Myr. The full color-magnitude diagram (CMD) fitting analysis shows that all three fields in our data set are consistent with ∼75% of the stellar mass being older than 8 Gyr, in spite of showing a wide range in star formation rates at present. Thus, our results suggest that the scale length of NGC 4214 has remained relatively constant for many gigayears. As previously noted by others, we also find the galaxy has recently ramped up production consistent with its bright UV luminosity and its population of UV-bright massive stars. In the central field we find UV point sources with F336W magnitudes as bright as -9.9. These are as bright as stars with masses of at least 52-56 Msun and ages near 4 Myr in stellar evolution models. Assuming a standard initial mass function, our CMD is well fitted by an increase in star formation rate beginning 100 Myr ago. The stellar populations of this late-type dwarf are compared with those of NGC 404, an early-type dwarf that is also the most massive galaxy in its local environment. The late-type dwarf appears to have a similar high fraction of ancient stars, suggesting that these dominant galaxies may form at early epochs even if they have low total mass and very different present-day morphologies.

  4. Highest Redshift Image of Neutral Hydrogen in Emission: A CHILES Detection of a Starbursting Galaxy at z=0.376

    Fernández, Ximena; van Gorkom, J H; Yun, Min S; Momjian, Emmanuel; Popping, Attila; Chomiuk, Laura; Hess, Kelley M; Hunt, Lucas; Kreckel, Kathryn; Lucero, Danielle; Maddox, Natasha; Oosterloo, Tom; Pisano, D J; Verheijen, M A W; Hales, Christopher A; Chung, Aeree; Dodson, Richard; Golap, Kumar; Gross, Julia; Henning, Patricia; Hibbard, John; Jaffé, Yara L; Meyer, Jennifer Donovan; Meyer, Martin; Sanchez-Barrantes, Monica; Schiminovich, David; Wicenec, Andreas; Wilcots, Eric; Bershady, Matthew; Scoville, Nick; Strader, Jay; Tremou, Evangelia; Salinas, Ricardo; Chávez, Ricardo

    2016-01-01

    Our current understanding of galaxy evolution still has many uncertainties associated with the details of accretion, processing, and removal of gas across cosmic time. The next generation of radio telescopes will image the neutral hydrogen (HI) in galaxies over large volumes at high redshifts, which will provide key insights into these processes. We are conducting the COSMOS HI Large Extragalactic Survey (CHILES) with the Karl G. Jansky Very Large Array, which is the first survey to simultaneously observe HI from z=0 to z~0.5. Here, we report the highest redshift HI 21-cm detection in emission to date of the luminous infrared galaxy (LIRG) COSMOS J100054.83+023126.2 at z=0.376 with the first 178 hours of CHILES data. The total HI mass is $(2.9\\pm1.0)\\times10^{10}~M_\\odot$, and the spatial distribution is asymmetric and extends beyond the galaxy. While optically the galaxy looks undisturbed, the HI distribution suggests an interaction with candidate a candidate companion. In addition, we present follow-up Larg...

  5. Radiative feedback from massive black holes in elliptical galaxies. AGN flaring and central starburst fueled by recycled gas

    Ciotti, L

    2007-01-01

    The importance of the radiative output from massive black holes at the centers of elliptical galaxies is not in doubt, given the well established relations among electromagnetic output, black hole mass and galaxy optical luminosity. We show how this AGN radiative output affects the hot ISM of an isolated elliptical galaxy with the aid of a high-resolution hydrodynamical code, where the cooling and heating functions include photoionization plus Compton heating. We find that radiative heating is a key factor in the self-regulated coevolution of massive black holes and their host galaxies and that 1) the mass accumulated by the central black hole is limited by feedback to the range observed today, and 2) relaxation instabilities occur so that duty cycles are small enough (~0.03) to account for the very small fraction of massive ellipticals observed to be in the "on" -QSO- phase, when the accretion luminosity approaches the Eddington luminosity. The duty cycle of the hot bubbles inflated at the galaxy center duri...

  6. The XMM Cluster Survey: Active Galactic Nuclei and Starburst Galaxies in XMMXCS J2215.9-1738 at z=1.46

    Hilton, Matt; Stanford, S Adam; Stott, John P; Collins, Chris A; Romer, A Kathy; Hosmer, Mark; Hoyle, Ben; Kay, Scott T; Liddle, Andrew R; Mehrtens, Nicola; Miller, Christopher J; Sahlén, Martin; Viana, Pedro T P

    2010-01-01

    We use Chandra X-ray and Spitzer infrared observations to explore the AGN and starburst populations of XMMXCS J2215.9-1738 at z=1.46, one of the most distant spectroscopically confirmed galaxy clusters known. The high resolution X-ray imaging reveals that the cluster emission is contaminated by point sources that were not resolved in XMM observations of the system, and have the effect of hardening the spectrum, leading to the previously reported temperature for this system being overestimated. From a joint spectroscopic analysis of the Chandra and XMM data, the cluster is found to have temperature T=4.1_-0.9^+0.6 keV and luminosity L_X=(2.92_-0.35^+0.24)x10^44 erg/s extrapolated to a radius of 2 Mpc. As a result of this revised analysis, the cluster is found to lie on the sigma_v-T relation, but the cluster remains less luminous than would be expected from self-similar evolution of the local L_X-T relation. Two of the newly discovered X-ray AGN are cluster members, while a third object, which is also a promin...

  7. Cosmic rays and the magnetic field in the nearby starburst galaxy NGC253 III. Helical magnetic fields in the nuclear outflow

    Heesen, Volker; Krause, Marita; Dettmar, Ralf-Jürgen

    2011-01-01

    Magnetic fields are a good tracer for gas compression by shock waves, which can be caused by interaction of star-formation driven outflows from individual star formation sites as described in the chimney model. We study the magnetic field structure in the central part of the nuclear starburst galaxy NGC 253 with spatial resolutions between 40 and 150 pc to detect any filamentary emission associated with the nuclear outflow. New VLA observations at 3 cm with 7.5" resolution were combined with archive data at 20 and 6 cm. We find filamentary radio continuum emission in a geometrical distribution that we interpret as the boundary of the northwestern nuclear outflow cone. The scaleheight of the continuum emission is 150+/-20 pc, regardless of the observing frequency. The equipartition magnetic field strength is 46+/-10 microG for the total field and 21+/-5 microG for the regular field in the filaments. The ordered magnetic field is aligned along the filaments, in agreement with amplification due to compression. T...

  8. Variations of the stellar initial mass function in the progenitors of massive early-type galaxies and in extreme starburst environments

    Chabrier, G; Charlot, P

    2014-01-01

    We examine variations of the stellar initial mass function (IMF) in extreme environments within the formalism derived by Hennebelle \\& Chabrier. We focus on conditions encountered in progenitors of massive early type galaxies and starburst regions. We show that, when applying the concept of turbulent Jeans mass as the characteristic mass for fragmentation in a turbulent medium, instead of the standard thermal Jeans mass for purely gravitational fragmentation, the peak of the IMF in such environments is shifted towards smaller masses, leading to a bottom-heavy IMF, as suggested by various observations. In very dense and turbulent environments, we predict that the high-mass tail of the IMF can become even steeper than the standard Salpeter IMF, with a limit for the power law exponent $\\alpha\\simeq -2.7$, in agreement with recent observational determinations. This steepening is a direct consequence of the high densities and Mach values in such regions but also of the time dependence of the fragmentation proc...

  9. Karl G. Jansky very large array observations of cold dust and molecular gas in starbursting quasar host galaxies at z ∼ 4.5

    We present Karl G. Jansky Very Large Array (VLA) observations of 44 GHz continuum and CO J = 2-1 line emission in BRI 1202–0725 at z = 4.7 (a starburst galaxy and quasar pair) and BRI 1335–0417 at z = 4.4 (also hosting a quasar). With the full 8 GHz bandwidth capabilities of the upgraded VLA, we study the (rest-frame) 250 GHz thermal dust continuum emission for the first time along with the cold molecular gas traced by the low-J CO line emission. The measured CO J = 2-1 line luminosities of BRI 1202–0725 are LCO′=(8.7±0.8)×1010 K km s–1 pc2 and LCO′=(6.0 ± 0.5)×1010 K km s–1 pc2 for the submillimeter galaxy (SMG) and quasar, respectively, which are equal to previous measurements of the CO J = 5-4 line luminosities implying thermalized line emission, and we estimate a combined cold molecular gas mass of ∼9×1010 M ☉. In BRI 1335–0417 we measure LCO′=(7.3±0.6)×1010 K km s–1 pc2. We detect continuum emission in the SMG BRI 1202–0725 North (S 44 GHz = 51 ± 6 μJy), while the quasar is detected with S 44 GHz = 24 ± 6 μJy and in BRI 1335–0417 we measure S 44 GHz = 40 ± 7 μJy. Combining our continuum observations with previous data at (rest-frame) far-infrared and centimeter wavelengths, we fit three-component models in order to estimate the star formation rates. This spectral energy distribution fitting suggests that the dominant contribution to the observed 44 GHz continuum is thermal dust emission, while either thermal free-free or synchrotron emission contributes less than 30%.

  10. IONIZATION PARAMETER AS A DIAGNOSTIC OF RADIATION AND WIND PRESSURES IN H II REGIONS AND STARBURST GALAXIES

    The ionization parameter U is potentially useful as a tool to measure radiation pressure feedback from massive star clusters, as it directly reflects the ratio of radiation to gas pressure and is readily derived from mid-infrared line ratios. We consider a number of physical effects which combine to determine the apparent value of U in observations encompassing one or many H II regions. An upper limit is set by the compression of gas by radiation pressure, when this is important. The pressure of shocked stellar winds and the presence of neutral clumps both tend to reduce U for a given intensity of irradiation. The most intensely irradiated regions are selectively dimmed by internal dust absorption of ionizing photons, leading to a bias for observations on galactic scales. We explore these effects in analytical and numerical models for dusty H II regions and use them to interpret previous observational results. We find that radiation pressure confinement sets the upper limit log10U≅-1 seen in individual regions. Unresolved starbursts are known to display a maximum value of ≅ – 2.3. While lower, this is also consistent with a large portion of their H II regions being radiation pressure dominated, given the different technique used to interpret unresolved regions, and given the bias caused by dust absorption. We infer that many individual, strongly illuminated regions cannot be significantly overpressured by stellar winds, and that even when averaged on galactic scales, the shocked wind pressure cannot be large compared to radiation pressure. Therefore, most H II regions cannot be adiabatic wind bubbles. Our models imply a metallicity dependence in the physical structure and dust attenuation of radiation-dominated regions, both of which should vary strongly across a critical metallicity of about one-twentieth solar.

  11. IONIZATION PARAMETER AS A DIAGNOSTIC OF RADIATION AND WIND PRESSURES IN H II REGIONS AND STARBURST GALAXIES

    Yeh, Sherry C. C.; Matzner, Christopher D. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, ON M5S 3H4 (Canada)

    2012-10-01

    The ionization parameter U is potentially useful as a tool to measure radiation pressure feedback from massive star clusters, as it directly reflects the ratio of radiation to gas pressure and is readily derived from mid-infrared line ratios. We consider a number of physical effects which combine to determine the apparent value of U in observations encompassing one or many H II regions. An upper limit is set by the compression of gas by radiation pressure, when this is important. The pressure of shocked stellar winds and the presence of neutral clumps both tend to reduce U for a given intensity of irradiation. The most intensely irradiated regions are selectively dimmed by internal dust absorption of ionizing photons, leading to a bias for observations on galactic scales. We explore these effects in analytical and numerical models for dusty H II regions and use them to interpret previous observational results. We find that radiation pressure confinement sets the upper limit log{sub 10}U{approx_equal}-1 seen in individual regions. Unresolved starbursts are known to display a maximum value of {approx_equal} - 2.3. While lower, this is also consistent with a large portion of their H II regions being radiation pressure dominated, given the different technique used to interpret unresolved regions, and given the bias caused by dust absorption. We infer that many individual, strongly illuminated regions cannot be significantly overpressured by stellar winds, and that even when averaged on galactic scales, the shocked wind pressure cannot be large compared to radiation pressure. Therefore, most H II regions cannot be adiabatic wind bubbles. Our models imply a metallicity dependence in the physical structure and dust attenuation of radiation-dominated regions, both of which should vary strongly across a critical metallicity of about one-twentieth solar.

  12. Ionization Parameter as a Diagnostic of Radiation and Wind Pressures in H II Regions and Starburst Galaxies

    Yeh, Sherry C. C.; Matzner, Christopher D.

    2012-10-01

    The ionization parameter {\\cal U} is potentially useful as a tool to measure radiation pressure feedback from massive star clusters, as it directly reflects the ratio of radiation to gas pressure and is readily derived from mid-infrared line ratios. We consider a number of physical effects which combine to determine the apparent value of {\\cal U} in observations encompassing one or many H II regions. An upper limit is set by the compression of gas by radiation pressure, when this is important. The pressure of shocked stellar winds and the presence of neutral clumps both tend to reduce {\\cal U} for a given intensity of irradiation. The most intensely irradiated regions are selectively dimmed by internal dust absorption of ionizing photons, leading to a bias for observations on galactic scales. We explore these effects in analytical and numerical models for dusty H II regions and use them to interpret previous observational results. We find that radiation pressure confinement sets the upper limit log _{10} {\\cal U}\\simeq -1 seen in individual regions. Unresolved starbursts are known to display a maximum value of ~= - 2.3. While lower, this is also consistent with a large portion of their H II regions being radiation pressure dominated, given the different technique used to interpret unresolved regions, and given the bias caused by dust absorption. We infer that many individual, strongly illuminated regions cannot be significantly overpressured by stellar winds, and that even when averaged on galactic scales, the shocked wind pressure cannot be large compared to radiation pressure. Therefore, most H II regions cannot be adiabatic wind bubbles. Our models imply a metallicity dependence in the physical structure and dust attenuation of radiation-dominated regions, both of which should vary strongly across a critical metallicity of about one-twentieth solar.

  13. O vi Emission Imaging of a Galaxy with the Hubble Space Telescope: a Warm Gas Halo Surrounding the Intense Starburst SDSS J115630.63+500822.1

    Hayes, Matthew; Melinder, Jens; Östlin, Göran; Scarlata, Claudia; Lehnert, Matthew D.; Mannerström-Jansson, Gustav

    2016-09-01

    We report results from a new Hubble Space Telescope campaign that targets the O vi λ λ 1032,1038 Å doublet in emission around intensely star-forming galaxies. The program aims to characterize the energy balance in starburst galaxies and gas cooling in the difficult-to-map coronal temperature regime of 2{--}5× {10}5 K. We present the first resolved image of gas emission in the O vi line. Our target, SDSS J115630.63+500822.1, is very compact in the continuum but displays O vi emission to radii of 23 kpc. The surface brightness profile is well fit by an exponential with a scale length of 7.5 kpc. This is 10 times the size of the photoionized gas, and we estimate that about 1/6 the total O vi luminosity comes from resonantly scattered continuum radiation. Spectroscopy—which closely resembles a stacked sample of archival spectra—confirms the O vi emission, and determines the column density and outflow velocity from blueshifted absorption. The combination of measurements enables a large number of calculations with few assumptions. The O vi regions fill only ∼ {10}-3 of the volume. By comparing the cooling time with the cloud sound-crossing time, the cooling distance with the size, and the pressure in the O vi and nebular gas, we conclude that the O vi-bearing gas cannot have been lifted to the scale height at this temperature, and must be cooling in situ through this coronal temperature regime. The coronal phase contains ∼1% of the ionized mass, and its kinetic energy at a given instant is ∼1% of the budget set by supernova feedback. However, a much larger amount of the gas must have cooled through this phase during the star formation episode. The outflow exceeds the escape velocity and the gas may become unbound, but it will recombine before it escapes and become visible to Lyman (and O i) spectroscopy. The mapping of this gas represents a crucial step in further constraining galaxy formation scenarios and guiding the development of future astronomical

  14. The Feedback-Regulated Growth of Black Holes and Bulges through Gas Accretion and Starbursts in Cluster Central Dominant Galaxies

    Rafferty, D A; Nulsen, P E J; Wise, M W

    2006-01-01

    We present an analysis of the growth of black holes through accretion and bulges through star formation in 33 galaxies at the centers of cooling flows. Most of these systems show evidence of cavities in the intracluster medium (ICM) inflated by radio jets emanating from their active galactic nuclei (AGN). We present a new and extensive analysis of X-ray cavities in these systems. We find that AGN are energetically able to balance radiative losses (cooling) from the ICM in more than half of our sample. Using a subsample of 17 systems, we examine the relationship between cooling and star formation. We find that the star formation rates are approaching or are comparable to X-ray and far UV limits on the rates of gas condensation onto the central galaxy. The remaining radiative losses could be offset by AGN feedback. The vast gulf between radiative losses and the sink of cooling material, which has been the primary objection to cooling flows, has narrowed and, in some cases, is no longer a serious issue. Using th...

  15. The redshift and nature of AzTEC/COSMOS 1: A starburst galaxy at z=4.6

    Smolcic, V; Ilbert, O; Blain, A W; Salvato, M; Aretxaga, I; Schinnerer, E; Masters, D; Moric, I; Riechers, D A; Sheth, K; Aravena, M; Aussel, H; Aguirre, J; Berta, S; Carilli, C L; Civano, F; Fazio, G; Huang, J; Hughes, D; Kartaltepe, J; Koekemoer, A M; Kneib, J -P; LeFloc'h, E; Lutz, D; McCracken, H; Mobasher, B; Murphy, E; Pozzi, F; Riguccini, L; Sanders, D B; Sargent, M; Scott, K S; Scoville, N Z; Taniguchi, Y; Thompson, D; Willott, C; Wilson, G; Yun, M

    2011-01-01

    Based on broad/narrow-band photometry and Keck DEIMOS spectroscopy we report a redshift of z=4.64-0.08+0.06 for AzTEC/COSMOS 1, the brightest sub-mm galaxy in the AzTEC/COSMOS field. In addition to the COSMOS-survey X-ray to radio data, we report observations of the source with Herschel/PACS (100, 160 micron), CSO/SHARC II (350 micron), CARMA and PdBI (3 mm). We do not detect CO(5-4) line emission in the covered redshift ranges, 4.56-4.76 (PdBI/CARMA) and 4.94-5.02 (CARMA). If the line is within this bandwidth, this sets 3sigma upper limits on the gas mass to <~8x10^9 M_Sol and <~5x10^10 M_Sol, respectively (assuming similar conditions as observed in z~2 SMGs). This could be explained by a low CO-excitation in the source. Our analysis of the UV-IR spectral energy distribution of AzTEC 1 shows that it is an extremely young (<~50 Myr), massive (M*~10^11 M_Sol), but compact (<~2 kpc) galaxy forming stars at a rate of ~1300 M_Sol/yr. Our results imply that AzTEC 1 is forming stars in a 'gravitationall...

  16. A universal, turbulence-regulated star formation law: from Milky Way clouds to high-redshift disk and starburst galaxies

    Salim, Diane M; Kewley, Lisa J

    2015-01-01

    Whilst the star formation rate (SFR) of molecular clouds and galaxies is key in understanding galaxy evolution, the physical processes which determine the SFR remain unclear. This uncertainty about the underlying physics has resulted in various different star formation laws, all having substantial intrinsic scatter. Extending upon previous works that define the column density of star formation (Sigma_SFR) by the gas column density (Sigma_gas), we develop a new universal star formation (SF) law based on the multi-freefall prescription of gas. This new SF law relies predominantly on the probability density function (PDF) and on the sonic Mach number of the turbulence in the star-forming clouds. By doing so we derive a relation where the star formation rate (SFR) correlates with the molecular gas mass per multi-freefall time, whereas previous models had used the average, single-freefall time. We define a new quantity called maximum (multi-freefall) gas consumption rate (MGCR) and show that the actual SFR is only...

  17. THE REDSHIFT AND NATURE OF AzTEC/COSMOS 1: A STARBURST GALAXY AT z = 4.6

    Based on broadband/narrowband photometry and Keck DEIMOS spectroscopy, we report a redshift of z = 4.64+0.06-0.08 for AzTEC/COSMOS 1, the brightest submillimeter galaxy (SMG) in the AzTEC/COSMOS field. In addition to the COSMOS-survey X-ray to radio data, we report observations of the source with Herschel/PACS (100, 160 μm), CSO/SHARC II (350 μm), and CARMA and PdBI (3 mm). We do not detect CO(5 → 4) line emission in the covered redshift ranges, 4.56-4.76 (PdBI/CARMA) and 4.94-5.02 (CARMA). If the line is within this bandwidth, this sets 3σ upper limits on the gas mass to ∼9 Msun and ∼10 Msun, respectively (assuming similar conditions as observed in z ∼ 2 SMGs). This could be explained by a low CO-excitation in the source. Our analysis of the UV-IR spectral energy distribution of AzTEC 1 shows that it is an extremely young (∼* ∼ 1011 Msun), but compact (∼sun yr-1. Our results imply that AzTEC 1 is forming stars in a 'gravitationally bound' regime in which gravity prohibits the formation of a superwind, leading to matter accumulation within the galaxy and further generations of star formation.

  18. Star and dust formation activities in AzTEC-3: A starburst galaxy at z = 5.3

    Dwek, Eli; Arendt, Richard G; Capak, Peter L; Kovacs, Attila; Benford, Dominic; Fixsen, Dale; Karim, Alexander; Leclercq, Samuel; Maher, Stephen F; Moseley, Samuel H; Schinnerer, Eva; Sharp, Elmer H

    2011-01-01

    Analyses of high-redshift ultraluminous infrared (IR) galaxies traditionally use the observed optical to submillimeter spectral energy distribution (SED) and estimates of the dynamical mass as observational constraints to derive the star formation rate (SFR), the stellar mass, and age of these objects. An important observational constraint neglected in the analysis is the mass of dust giving rise to the IR emission. In this paper we add this constraint to the analysis of AzTEC-3. Adopting an upper limit to the mass of stars and a bolometric luminosity for this object, we construct stellar and chemical evolutionary scenarios, constrained to produce the inferred dust mass and observed luminosity before the associated stellar mass exceeds the observational limit. We find that the model with a Top Heavy IMF provided the most plausible scenario consistent with the observational constraints. In this scenario the dust formed over a period of ~200 Myr, with a SFR of ~500 Msun/yr. These values for the age and SFR in A...

  19. SMA Observations of the Extended 12CO(J = 6–5) Emission in the Starburst Galaxy NGC 253

    Krips, M.; Martín, S.; Peck, A. B.; Sakamoto, K.; Neri, R.; Gurwell, M.; Petitpas, G.; Zhao, Jun-Hui

    2016-04-01

    We present observations of the 12CO(J = 6–5) line and 686 GHz continuum emission in NGC 253 with the Submillimeter Array at an angular resolution of ∼4″. The 12CO(J = 6–5) emission is clearly detected along the disk and follows the distribution of the lower 12CO line transitions with little variation of the line ratios. A large velocity gradient analysis suggests a two-temperature model of the molecular gas in the disk, likely dominated by a combination of low-velocity shocks and the disk-wide photodissociation regions. Only marginal 12CO(J = 6–5) emission is detected in the vicinity of the expanding shells at the eastern and western edges of the disk. While the eastern shell contains gas even warmer (Tkin > 300 K) than the hot gas component (Tkin = 300 K) of the disk, the western shell is surrounded by gas much cooler (Tkin = 60 K) than the eastern shell but somewhat hotter than the cold gas component of the disk (for similar H2 and CO column densities), indicative of different (or differently efficient) heating mechansisms. The continuum emission at 686 GHz in the disk agrees well in shape and size with that at lower (sub)millimeter frequencies, exhibiting a spectral index consistent with thermal dust emission. We find dust temperatures of ∼10–30 K and largely optically thin emission. However, our fits suggest a second (more optically thick) dust component at higher temperatures ({T}{{d}}\\gt 60 K), similar to the molecular gas. We estimate a global dust mass of ∼106 {M}ȯ for the disk, translating into a gas-to-dust mass ratio of a few hundred, consistent with other nearby active galaxies.

  20. Revealing the ISM in high redshift starburst galaxies: An analysis of Herschel PACS and SPIRE FTS spectroscopic observations of HerMES and H-ATLAS-selected lensed galaxies

    Cooray, Asantha

    In the quest to develop a fundamental understanding of galaxy formation and evolution, observations of dusty star-forming galaxies (DSFGs) promise significant progress this decade. The importance of DSFGs is highlighted by the fact that half of the energy emitted by extragalactic sources emerges as dust-reprocessed light at infrared (IR) to sub millimeter wavelength. In the post-herschel\\ era, we are now at a unique position to tackle some of the key questions on galaxy formation and evolution because of the large area Herschel's Key Project surveys (HerMES and H-ATLAS). In particular those surveys have allowed us to identify a sample of 250 strongly gravitationally lensed DSFGs at z > 1. They give us a unique opportunity to dissect the detailed structures and kinematics of DSFGs. The Herschel Science Archive also contains individual follow up data on 44 and 25 of the brightest sources with SPIRE-FTS and PACS, respectively, in the spectroscopy mode, taking over 250 hours in four open-time programs. Only one of the 44 SPIRE FTS targets has yet to appear in the published literature. One of the four include an open-time 2 PACS spectroscopy program that was led at UCI by a former postdoc from the PI's group. That program was initially approved at Priority 2 in 2011, but was triggered in late 2012 and achieved 100% completion during the last two weeks of Herschel lifetime in May 2013. This archival analysis, interpretation, and modeling program involves two parts: (i) PACS spectroscopy in 50 to 200 microns of 25 lensed galaxies in the fine-structure emission lines [SiII]34, [SIII]33, [OIV]26, [OIII]52, [NIII]57 and [OI]63, and the molecular hydrogen H_2 S(0) and S(1). (ii) SPIRE FTS spectroscopy of 44 lensed galaxies, including above 25, over the wavelength range of 200 to 600 microns targeting [CII]158, [OIII]88, [OI]63/145, and [NI]122. The analysis will lead to a better understanding of the ISM of starbursting galaxies that span 1 peer-reviewed literature. The

  1. SMBH Luminosity in the Starburst Environment

    Silich, S.; Tenorio-Tagle, G.; Hueyotl-Zahuantitla, F.; Palouš, Jan; Wünsch, Richard

    Cambridge : Cambridge University Press, 2010 - (Peterson, B.). s. 336-336 ISBN 978-0-521-76502-2. [Symposium of the International Astronomical Union /267./. 10.08.2009-14.08.2009, Rio de Janeiro] Institutional research plan: CEZ:AV0Z10030501 Keywords : Seyfert, galaxies * starburst, accretion * hydrodynamics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  2. Star Formation in Galaxies

    1987-01-01

    Topics addressed include: star formation; galactic infrared emission; molecular clouds; OB star luminosity; dust grains; IRAS observations; galactic disks; stellar formation in Magellanic clouds; irregular galaxies; spiral galaxies; starbursts; morphology of galactic centers; and far-infrared observations.

  3. Star-formation laws in extreme starbursts

    Garcia-Burillo, S; Alonso-Herrero, A

    2012-01-01

    The observational study of star-formation laws is paramount to disentangling the physical processes at work on local and global scales in galaxies. To this aim we have expanded the sample of extreme starbursts, represented by local LIRGs and ULIRGs, with high-quality data obtained in the 1-0 line of HCN. The analysis of the new data shows that the star-formation efficiency of the dense molecular gas, derived from the FIR/HCN luminosity ratio, is a factor 3-4 higher in extreme starbursts compared to normal galaxies. We find a duality in the Kennicutt-Schmidt laws that is enhanced if we account for the different conversion factor for HCN (alpha_HCN) in extreme starbursts and correct for the unobscured star-formation rate in normal galaxies. We find that it is possible to fit the observed differences in the FIR/HCN ratios between normal galaxies and LIRGs/ULIRGs with a common constant star-formation rate per free-fall time (SFR_ff) if we assume that HCN densities are ~1-2 orders of magnitude higher in LIRGs/ULIR...

  4. THE NATURE OF STARBURSTS. III. THE SPATIAL DISTRIBUTION OF STAR FORMATION

    We map the spatial distribution of recent star formation over a few × 100 Myr timescales in 15 starburst dwarf galaxies using the location of young blue helium burning stars identified from optically resolved stellar populations in archival Hubble Space Telescope observations. By comparing the star formation histories from both the high surface brightness central regions and the diffuse outer regions, we measure the degree to which the star formation has been centrally concentrated during the galaxies' starbursts, using three different metrics for the spatial concentration. We find that the galaxies span a full range in spatial concentration, from highly centralized to broadly distributed star formation. Since most starbursts have historically been identified by relatively short timescale star formation tracers (e.g., Hα emission), there could be a strong bias toward classifying only those galaxies with recent, centralized star formation as starbursts, while missing starbursts that are spatially distributed.

  5. THE NATURE OF STARBURSTS. III. THE SPATIAL DISTRIBUTION OF STAR FORMATION

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

    2012-11-01

    We map the spatial distribution of recent star formation over a few Multiplication-Sign 100 Myr timescales in 15 starburst dwarf galaxies using the location of young blue helium burning stars identified from optically resolved stellar populations in archival Hubble Space Telescope observations. By comparing the star formation histories from both the high surface brightness central regions and the diffuse outer regions, we measure the degree to which the star formation has been centrally concentrated during the galaxies' starbursts, using three different metrics for the spatial concentration. We find that the galaxies span a full range in spatial concentration, from highly centralized to broadly distributed star formation. Since most starbursts have historically been identified by relatively short timescale star formation tracers (e.g., H{alpha} emission), there could be a strong bias toward classifying only those galaxies with recent, centralized star formation as starbursts, while missing starbursts that are spatially distributed.

  6. The Nature of Starbursts: III. The Spatial Distribution of Star Formation

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

    2012-01-01

    We map the spatial distribution of recent star formation over a few x 100 Myr timescales in fifteen starburst dwarf galaxies using the location of young blue helium burning stars identified from optically resolved stellar populations in archival Hubble Space Telescope observations. By comparing the star formation histories from both the high surface brightness central regions and the diffuse outer regions, we measure the degree to which the star formation has been centrally concentrated during the galaxies' starbursts, using three different metrics for the spatial concentration. We find that the galaxies span a full range in spatial concentration, from highly centralized to broadly distributed star formation. Since most starbursts have historically been identified by relatively short timescale star formation tracers (e.g., Halpha emission), there could be a strong bias towards classifying only those galaxies with recent, centralized star formation as starbursts, while missing starbursts that are spatially dis...

  7. Decoding spectral energy distributions of dust-obscured starburst-AGN

    Han, Yunkun

    2012-01-01

    We present BayeSED, a general purpose tool for doing Bayesian analysis of SEDs by using whatever pre-existing model SED libraries or their linear combinations. The artificial neural networks (ANNs), principal component analysis (PCA) and multimodal nested sampling (MultiNest) techniques are employed to allow a highly efficient sampling of posterior distribution and the calculation of Bayesian evidence. As a demonstration, we apply this tool to a sample of hyperluminous infrared galaxies (HLIRGs). The Bayesian evidences obtained for a pure Starburst, a pure AGN, and a linear combination of Starburst+AGN models show that the Starburst+AGN model have the highest evidence for all galaxies in this sample. The Bayesian evidences for the three models and the estimated contributions of starburst and AGN to infrared luminosity show that HLIRGs can be classified into two groups: one dominated by starburst and the other dominated by AGN. Other parameters and corresponding uncertainties about starburst and AGN are also e...

  8. PAHS AS TRACERS OF LOCAL AGN-STARBURST CONNECTION

    Mario-A. Higuera-G.

    2013-01-01

    Full Text Available The main purpose of this research was to investigate how energetic processes associated with active galactic nuclei (AGN are related to those due to nuclear or circumnuclear star formation activity. Photometric and spectroscopic data were used to discriminate between these processes in a sample of starburst, infrared galaxies and AGNs. Here, we propose new diagnostic diagrams based on the 7.7 μm polycyclic aromatic hydrocarbon emission band, the L(MIR,FIR infrared ratio and the q parameter. The diagnostic diagrams allow us to discriminate the behavior of quasars and Seyfert 1-Seyfert 2 galaxies from starbursts and LIRGs-ULIRGs objects.

  9. A Spectacular Post-Starburst Quasar

    Brotherton, M S; Stanford, S A; Smith, R J; Boyle, B J; Miller, L; Shanks, T; Croom, S M; Filippenko, A V; Breugel, Wil van; Miller, Lance; Filippenko, Alexei V.

    1999-01-01

    We report the discovery of a spectacular ``post-starburst quasar'' UN J1025-0040 (B=19; z=0.634). The optical spectrum is a chimera, displaying the broad Mg II emission line and strong blue continuum characteristic of quasars, but is dominated in the red by a large Balmer jump and prominent high-order Balmer absorption lines indicative of a substantial young stellar population at similar redshift. Stellar synthesis population models show that the stellar component is consistent with a 400 Myr old instantaneous starburst with a mass of less than or about 10^{11} solar masses. A deep, K_s-band image taken in 0.5 arcsec seeing shows a point source surrounded by asymmetric extended fuzz. Approximately 70% of the light is unresolved, the majority of which is expected to be emitted by the starburst. While starbursts and galaxy interactions have been previously associated with quasars, no quasar ever before has been seen with such an extremely luminous young stellar population.

  10. A Revised Host Galaxy Association for GRB 020819B: A High-Redshift Dusty Starburst, Not a Low-Redshift Gas-Poor Spiral

    Perley, Daniel A; Schady, Patricia; Michałowski, Michał J; Thöne, Christina C; Petry, Dirk; Graham, John F; Greiner, Jochen; Schulze, Steve; Kim, Sam

    2016-01-01

    The purported spiral host galaxy of GRB 020819B at z=0.41 has been seminal in establishing our view of the diversity of long-duration gamma-ray burst environments: optical spectroscopy of this host provided evidence that GRBs can form even at high metallicities, while millimetric observations suggested that GRBs may preferentially form in regions with minimal molecular gas. We report new observations from VLT (MUSE and X-shooter) which demonstrate that the purported host is an unrelated foreground galaxy. The probable radio afterglow is coincident with a compact, highly star-forming, dusty galaxy at z=1.9621. The revised redshift naturally explains the apparent nondetection of CO(3-2) line emission at the afterglow site from ALMA. There is no evidence that molecular gas properties in GRB host galaxies are unusual, and limited evidence that GRBs can form readily at super-Solar metallicity.

  11. The Role of Radiation Feedback in Starburst Environments

    Yeh, Sherry; Matzner, C. D.; Seaquist, E. R.

    2012-01-01

    Massive bursts of stellar activity in starburst environments feed prodigious amount of energy and momentum into the surrounding neutral clouds. With sufficiently intense irradiation from starbursts, the structure of an HII region will be dominated by radiation pressure rather than ionized gas pressure, and radiative energy input in photodissociation regions (PDRs) becomes more important. This state is of considerable interest because of its role in the formation of massive stars, the disruption of giant molecular clouds, and the evolution of starburst galaxies. We study the role of radiation feedback in starburst environments via both theoretical and observational approaches. We argue that radiation pressure is the underlying mechanism for the remarkable constancy of ionization parameters in starburst environments. We also point out that clumping in the neutral material and compression by stellar wind pressure can act to reduce ionization parameters. We use the Cloudy code to determine effective ionization parameters for a population of static dusty HII regions compressed by both radiation pressure and stellar winds. We conclude that the inner starburst region of M82 and the Antennae Galaxies HII regions are both dominated by a combination of radiation pressure and shocked winds. We investigate radiative energy feedback in starburst environments by observing the nearest starburst region 30 Doradus in the LMC. We observe 30 Doradus using NOAO Extremely Wide-Field Infrared Imager (NEWFIRM) with H2 1-0 S(1), Brγ, and [FeII] lines. While H2 can be either radiative or shock excited, the near infrared [FeII] emission line traces shock activities, and the hydrogen recombination line Brγ arises from regions ionized by UV radiation. Therefore ratios of the three emission lines form very useful diagnostics to assess the fraction of radiative and shock feedback. We preliminarily suggest that radiative energy input in the 30 Doradus PDRs is non-negligible.

  12. Starburst99 for Windows

    Leitherer, Claus

    2008-01-01

    We describe a Windows compatible version of the evolutionary synthesis code Starburst99. Starburst99 for Windows was developed from the public UNIX based version at STScI. We converted the original Fortran77 source code into a version for a Win32 environment with an Absoft Fortran Pro x86 compiler. Extensive testing showed no significant numerical differences in comparison with the previous UNIX version. The software application consists of the source code, executable, and a number of auxiliary files. The package installs on any PC running Windows 2000, XP, or Vista and can be obtained as freeware at http://www.stsci.edu/science/starburst/PCStarburst99.html. We give an overview of the different running modes and provide instructions for getting started with the initial set-up.

  13. Young star clusters in starburst environments

    Ho, L C

    1996-01-01

    Recent high-resolution observations with the Hubble Space Telescope (HST) reveal that young star clusters of extraordinary luminosity and compactness ("super star clusters") are commonly found in starburst systems. Cluster formation appears to be a dominant mode of star formation in starbursts. The principal properties of the young clusters are summarized. A new ultraviolet HST imaging survey of the central regions of nearby galaxies indicates that young clusters form in a wide range of environments. Circumnuclear star-forming rings, in particular, are richly populated with clusters, and several examples from recent imaging studies are discussed. There has been much speculation that super star clusters represent present-day analogs of young globular clusters. I will present evidence suggesting that at least some super star clusters indeed have masses and mass densities comparable to those of evolved globular clusters in the Milky Way.

  14. A CHANDRA OBSERVATION OF THE ULTRALUMINOUS INFRARED GALAXY IRAS 19254–7245 (THE SUPERANTENNAE): X-RAY EMISSION FROM THE COMPTON-THICK ACTIVE GALACTIC NUCLEUS AND THE DIFFUSE STARBURST

    We present a Chandra observation of IRAS 19254–7245, a nearby ultraluminous infrared galaxy also known as the Superantennae. The high spatial resolution of Chandra allows us to disentangle for the first time the diffuse starburst (SB) emission from the embedded Compton-thick active galactic nucleus (AGN) in the southern nucleus. No AGN activity is detected in the northern nucleus. The 2-10 keV spectrum of the AGN emission is fitted by a flat power law (Γ = 1.3) and an He-like Fe Kα line with equivalent width ∼1.5 keV, consistent with previous observations. The Fe Kα line profile could be resolved as a blend of a neutral 6.4 keV line and an ionized 6.7 keV (He-like) or 6.9 keV (H-like) line. Variability of the neutral line is detected compared with the previous XMM-Newton and Suzaku observations, demonstrating the compact size of the iron line emission. The spectrum of the galaxy-scale extended emission excluding the AGN and other bright point sources is fitted with a thermal component with a best-fit kT of ∼0.8 keV. The 2-10 keV luminosity of the extended emission is about one order of magnitude lower than that of the AGN. The basic physical and structural properties of the extended emission are fully consistent with a galactic wind being driven by the SB. A candidate ultraluminous X-ray source is detected 8'' south of the southern nucleus. The 0.3-10 keV luminosity of this off-nuclear point source is ∼6 × 1040 erg s–1 if the emission is isotropic and the source is associated with the Superantennae.

  15. A Chandra Observation of the Ultraluminous Infrared Galaxy IRAS 19254-7245 (The Superantennae): X-Ray Emission from the Compton-Thick Active Galactic Nucleus and the Diffuse Starburst

    Jia, Jianjun; Ptak, Andrew; Heckman, Timothy M.; Braito, Valentina; Reeves, James

    2012-01-01

    We present a Chandra observation of IRAS 19254-7245, a nearby ultraluminous infrared galaxy also known as the Superantennae. The high spatial resolution of Chandra allows us to disentangle for the first time the diffuse starburst (SB) emission from the embedded Compton-thick active galactic nucleus (AGN) in the southern nucleus. No AGN activity is detected in the northern nucleus. The 2-10 keV spectrum of the AGN emission is fitted by a flat power law (TAU = 1.3) and an He-like Fe Kalpha line with equivalent width 1.5 keV, consistent with previous observations. The Fe K line profile could be resolved as a blend of a neutral 6.4 keV line and an ionized 6.7 keV (He-like) or 6.9 keV (H-like) line. Variability of the neutral line is detected compared with the previous XMM-Newton and Suzaku observations, demonstrating the compact size of the iron line emission. The spectrum of the galaxy-scale extended emission excluding the AGN and other bright point sources is fitted with a thermal component with a best-fit kT of approximately 0.8 keV. The 2-10 keV luminosity of the extended emission is about one order of magnitude lower than that of the AGN. The basic physical and structural properties of the extended emission are fully consistent with a galactic wind being driven by the SB. A candidate ultraluminous X-ray source is detected 8 south of the southern nucleus. The 0.3 - 10 keV luminosity of this off-nuclear point source is approximately 6 x 10(exp 40) erg per second if the emission is isotropic and the source is associated with the Superantennae.

  16. Galaxies at High Redshifts

    Yahil, A.; Lanzetta, K. M.; Fernandez-Soto, A.

    1998-01-01

    Several conclusions have been reached over the last few years concerning high-redshift galaxies: (1) The excess of faint blue galaxies is due to dwarf galaxies. (2) Star formation peaks at redshifts z ~1-2. (3) It appears to occur piecemeal in any given galaxy and there is no evidence for starbursting throughout a large ~10 kpc galaxy. (4) There is significant and sharp diminution in the number of L* spiral galaxies at redshifts 1

  17. SPITZER MID-IR SPECTROSCOPY OF POWERFUL 2 JY AND 3CRR RADIO GALAXIES. I. EVIDENCE AGAINST A STRONG STARBURST-AGN CONNECTION IN RADIO-LOUD AGN

    We present deep Spitzer/Infrared Spectrograph (IRS) spectra for complete samples of 46 2 Jy radio galaxies (0.05 75%) than their more extended counterparts (≈15%-25%). We discuss this result in the context of a possible bias toward the selection of compact radio sources triggered in gas-rich environments.

  18. Hubble Space Telescope Grism Spectroscopy of Extreme Starbursts Across Cosmic Time: The Role of Dwarf Galaxies in the Star Formation History of the Universe

    Atek, Hakim; Pacifici, Camilla; Malkan, Matthew; Charlot, Stephane; Lee, Janice; Bedregal, Alejandro; Bunker, Andrew J; Colbert, James W; Dressler, Alan; Hathi, Nimish; Lehnert, Matthew; Martin, Crystal L; McCarthy, Patrick; Rafelski, Marc; Ross, Nathaniel; Siana, Brian; Teplitz, Harry I

    2014-01-01

    Near infrared slitless spectroscopy with the Wide Field Camera 3, onboard the Hubble Space Telescope, offers a unique opportunity to study low-mass galaxy populations at high-redshift ($z\\sim$1-2). While most high$-z$ surveys are biased towards massive galaxies, we are able to select sources via their emission lines that have very-faint continua. We investigate the star formation rate (SFR)-stellar mass ($M_{\\star}$) relation for about 1000 emission-line galaxies identified over a wide redshift range of $0.3 \\lesssim z \\lesssim 2.3$. We use the H$_{\\alpha}$ emission as an accurate SFR indicator and correct the broadband photometry for the strong nebular contribution to derive accurate stellar masses down to $M_{\\star} \\sim 10^{7} M_{\\odot}$. We focus here on a subsample of galaxies that show extremely strong emission lines (EELGs) with rest-frame equivalent widths ranging from 200 to 1500 \\AA. This population consists of outliers to the normal SFR-$M_{\\star}$ sequence with much higher specific SFRs ($> 10$ Gy...

  19. Star Formation in Extreme Starburst Environments - "Super" Star Clusters

    De Grijs, R

    2003-01-01

    The currently available empirical evidence on the star formation processes in the extreme, high-pressure environments induced by galaxy encounters, mostly based on high-resolution Hubble Space Telescope imaging observations, strongly suggests that star CLUSTER formation is an important and perhaps even the dominant mode of star formation in the starburst events associated with galaxy interactions. The production of "super star clusters" (SSCs; luminous, compact star clusters) seems to be a hallmark of intense star formation, particularly in interacting and starburst galaxies. Their sizes, luminosities, and mass estimates are entirely consistent with what is expected for young Milky Way-type globular clusters (GCs). SSCs are important because of what they can tell us about GC formation and evolution (e.g., initial characteristics and early survival rates). They are also of prime importance as probes of the formation and (chemical) evolution of their host galaxies, and of the initial mass function in the extrem...

  20. The Implications of Extreme Outflows from Extreme Starbursts

    Heckman, Timothy M.; Borthakur, Sanchayeeta

    2016-05-01

    Interstellar ultraviolet absorption lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis of the systematic properties of starburst-driven galactic outflows by expanding our sample to include a rare population of starbursts with exceptionally high outflow velocities. In principle, these could be a qualitatively different phenomenon from more typical outflows. However, we find that instead these starbursts lie on, or along the extrapolation of, the trends defined by the more typical systems studied previously by us. We exploit the wide dynamic range provided by this new sample to determine scaling relations of outflow velocity with galaxy stellar mass (M *), circular velocity, star formation rate (SFR), SFR/M *, and SFR/area. We argue that these results can be accommodated within the general interpretational framework we previously advocated, in which a population of ambient interstellar or circumgalactic clouds is accelerated by the combined forces of gravity and the momentum flux from the starburst. We show that this simple physical picture is consistent with both the strong cosmological evolution of galactic outflows in typical star-forming galaxies and the paucity of such galaxies with spectra showing inflows. We also present simple parameterizations of these results that can be implemented in theoretical models and numerical simulations of galaxy evolution.

  1. The Vertical Structure of Nuclear Starburst Disks: Testing a Model of AGN Obscuration

    Ballantyne, David R.; Gohil, Raj

    2016-04-01

    Nuclear starburst disks are Eddington-limited, radiation pressure supported disks that may be active in the nuclear environment of active galaxies (ULIRGS and AGNs). Earlier analytical models suggested that, under certain conditions, these disks may be geometrically thick on pc-scales, and thus could be a viable source for AGN obscuration, partcularly at z≤1, when gas factions in galaxies are still significant. Here, we present early results from numerical 2D models of nuclear starburst disks where the vertical structure is calculated explicitly from solving the hydrostatic balance and radiative transfer equations. We quantitatively assess under which conditions the starburst disk may present substantial obscuring columns for AGN observations.

  2. Gas-rich mergers and feedback are ubiqitous amongst starbursting radio galaxies, as revealed by JVLA, IRAM PdBI and Herschel

    Ivison, R J; Amblard, A; Arumugam, V; De Breuck, C; Emonts, B H C; Feain, I; Greve, T R; Haas, M; Ibar, E; Jarvis, M J; Kovaks, A; Lehnert, M D; Nesvadba, N P H; Rottgering, H J A; Seymour, N; Wylezalek, D

    2012-01-01

    We report new, sensitive observations of two z ~ 3-3.5 FIR-luminous radio galaxies, 6C1909+72 and B3J2330+3927, in 12CO J=1-0 with the Karl Jansky VLA and at 100-500um using Herschel, alongside new and archival 12CO J=4-3 observations from IRAM PdBI. We introduce a new colour-colour diagnostic plot to constrain the redshifts of several distant, dusty galaxies in our target fields. A bright SMG near 6C1909+72 likely shares the same node or filament as the signpost AGN, but it is not detected in CO despite ~20,000 km/s of velocity coverage. Also in the 6C1909+72 field, a large, red dust feature spanning ~500 kpc is aligned with the radio jet. We suggest several processes by which metal-rich material may have been transported, favouring a collimated outflow reminiscent of the jet-oriented metal enrichment seen in local cluster environments. Our interferometric imaging reveals a gas-rich companion to B3J2330+3927; indeed, all bar one of the eight z >~ 2 radio galaxies (or companions) detected in CO provide some e...

  3. Mergers, Interactions, and The Fueling of Starbursts

    Hibbard, J E

    1997-01-01

    The most active starbursts are found in galaxies with the highest IR luminosities, with peak star formation rates and efficiencies that are over an order of magnitude higher than in normal disk systems. These systems are almost exclusively on-going mergers. In this review I explore the conditions needed for interactions to experience such a phase by comparing two systems at similar stages of merging but quite different IR luminosities: NGC 4038/9 and Arp 299. These observations show that the most intense starbursts occur at the sites with the highest gas densities, which is a general result for IR luminous mergers. Observations and theory both suggest that the strength of the merger induced starburst depends on the internal structure of the progenitors, the amount and distribution of the gas, and the violence of the interaction. In particular, interactions involving progenitors with dense bulges, gas-rich disks, and/or a retrograde spin are expected to preferentially lead to large amounts of gaseous dissipati...

  4. Supernova Remnants in the Fossil Starburst in M82

    De Grijs, R; Becker, G D; Chevalier, R A; Gallagher, J S; Grijs, Richard de; O'Connell, Robert W; Becker, George D; Chevalier, Roger A; Gallagher, John S

    1999-01-01

    We report the discovery of ten compact H-alpha-bright sources in the post-starburst region northeast of the center of M82, ``M82 B.'' These objects have H alpha luminosities and sizes consistent with Type II supernova remnants (SNRs). They fall on the same H alpha surface brightness-diameter (Sigma-D) relation defined by SNRs in other nearby star-forming galaxies, with the M82 candidates lying preferentially at the small diameter end. These are the first candidates for optically-visible SNRs in M82 outside the heavily obscured central starburst within ~250 pc from the galactic center. If these sources are SNRs, they set an upper limit to the end of the starburst in region ``B2,'' about 500 pc from the galaxy's core, of ~50 Myr. Region ``B1,'' about 1000 pc from the core, lacks good SNR candidates and is evidently somewhat older. This suggests star formation in the galaxy has propagated inward toward the present-day intense starburst core.

  5. Are spiral galaxies heavy smokers?

    The dustiness of spiral galaxies is discussed. Starburst galaxies and the shortage of truly bright spiral galaxies is cited as evidence that spiral galaxies are far dustier than has been thought. The possibility is considered that the dust may be hiding missing mass

  6. The Fermi Bubbles as Starburst Wind Termination Shocks

    Lacki, Brian C

    2013-01-01

    The enhanced star formation in the inner 100 pc of the Galaxy launches a superwind, reaching ~1600 km/s for M82-like parameters. The ram pressure of the wind is very low compared to more powerful starburst winds. I show that halo gas stops the wind a few kpc from the Galactic Center. I argue that the termination shock accelerates cosmic rays, and that the resulting Inverse Compton gamma-rays are visible as the Fermi Bubbles. The Bubbles are thus wind bubbles, which the starburst can inflate within 10 Myr. They remain in steady state as long as the starburst lasts. The shock may accelerate PeV electrons and ultra-high energy protons. The Bubbles may be analogs of galactic wind termination shocks in the intergalactic medium. I discuss the advantages and problems of this model.

  7. The Implications of Extreme Outflows from Extreme Starbursts

    Heckman, Timothy M

    2016-01-01

    Interstellar ultraviolet absorption-lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis of the systematic properties of starburst-driven galactic outflows by expanding our sample to include a rare population of starbursts with exceptionally high outflow velocities. In principle, these could be a qualitatively different phenomenon from more typical outflows. However, we find that instead these starbursts lie on, or along the extrapolation of, the trends defined by the more typical systems studied previously by us. We exploit the wide dynamic range provided by this new sample to determine scaling relations of outflow velocity with galaxy stellar mass (M*), circular velocity, star-formation rate (SFR), SFR/M*, and SFR/area. We argue that these results can be accommodated within the general interpretational framework we previously advocated, in which a population of ambient interstellar or circum-galactic clouds is accelerated by the combine...

  8. Equipartition and Cosmic Ray Energy Densities in Central Molecular Zones of Starbursts

    Yoast-Hull, Tova M; Zweibel, Ellen G

    2015-01-01

    The energy densities in magnetic fields and cosmic rays (CRs) in galaxies are often assumed to be in equipartition, allowing for an indirect estimate of the magnetic field strength from the observed radio synchrotron spectrum. However, both primary and secondary CRs contribute to the synchrotron spectrum, and the CR electrons also loose energy via bremsstrahlung and inverse Compton. While classical equipartition formulae avoid these intricacies, there have been recent revisions that account for the extreme conditions in starbursts. Yet, the application of the equipartition formula to starburst environments also presupposes that timescales are long enough to reach equilibrium. Here, we test equipartition in the central molecular zones (CMZs) of nearby starburst galaxies by modeling the observed gamma-ray spectra, which provide a direct measure of the CR energy density, and the radio spectra, which provide a probe of the magnetic field strength. We find that in starbursts, the magnetic field energy density is s...

  9. Nonthermal particles and photons in starburst regions and superbubbles

    Bykov, Andrei

    2015-01-01

    Starforming factories in galaxies produce compact clusters and loose associations of young massive stars. Fast radiation-driven winds and supernovae input their huge kinetic power into the interstellar medium in the form of highly supersonic and superalfvenic outflows. Apart from gas heating, collisionless relaxation of fast plasma outflows results in fluctuating magnetic fields and energetic particles. The energetic particles comprise a long-lived component which may contain a sizeable fraction of the kinetic energy released by the winds and supernova ejecta and thus modify the magnetohydrodynamic flows in the systems. We present a concise review of observational data and models of nonthermal emission from starburst galaxies, superbubbles, and compact clusters of massive stars. Efficient mechanisms of particle acceleration and amplification of fluctuating magnetic fields with a wide dynamical range in starburst regions are discussed. Sources of cosmic rays, neutrinos and multi-wavelength nonthermal emission ...

  10. The Fossil Starburst in M82

    De Grijs, R; Gallagher, J S; Grijs, Richard de; Connell, Robert W. O'; Gallagher, John S.

    2000-01-01

    (Abridged) We present high-resolution HST imaging in the optical (WFPC2) and near-infrared (NICMOS) of a disk region 1 kpc NE of the starburst core in the nearby galaxy M82. This region, M82 ``B,'' has been suspected to be a fossil starburst site in which an intense episode of star formation occurred over 100 Myr ago, and our new observations confirm this intepretation. We find a large, evolved system of super star clusters in M82 B; we identify a total of 113 super star cluster candidates. The clusters range in absolute magnitude from M_V^0 = -6 to -10, with a peak at -7.5. The derived age distribution suggests steady, continuing cluster formation at a modest rate at early times (> 2 Gyr ago), followed by a concentrated formation episode ~600 Myr ago and more recent suppression of cluster formation. The peak episode coincides with independent dynamical estimates for the last tidal encounter with M81. Our J and H band observations resolve the bright giant population in M82's disk for the first time. Star form...

  11. High energy (gamma)-ray emission from the starburst nucleus of NGC 253

    Domingo-Santamaria, E; Torres, D F

    2005-06-15

    The high density medium that characterizes the central regions of starburst galaxies and its power to accelerate particles up to relativistic energies make these objects good candidates as {gamma}-rays sources. In this paper, a self-consistent model of the multifrequency emission of the starburst galaxy NGC 253, from radio to gamma-rays, is presented. The model is in agreement with all current measurements and provides predictions for the high energy behavior of the NGC 253 central region. Prospects for observations with the HESS array and GLAST satellite are especially discussed.

  12. The Fermi bubbles as starburst wind termination shocks

    Lacki, Brian C.

    2014-10-01

    The enhanced star formation in the inner 100 pc of the Galaxy launches a superwind at ˜1600 km s-1 for M82-like parameters. The ram pressure of the wind is very low compared to more powerful starburst winds. I show that halo gas stops the wind a few kpc from the Galactic Centre. I suggest that the termination shock accelerates cosmic rays, and that the resulting inverse Compton γ-rays are visible as the Fermi bubbles. The bubbles are then wind bubbles, which the starburst can inflate within 10 Myr. They can remain in steady state as long as the starburst lasts. The shock may accelerate PeV electrons and EeV protons. The bubbles may be analogues of galactic wind termination shocks in the intergalactic medium. I discuss the advantages and problems of this model. I note that any jets from Sgr A* must burrow through the starburst wind bubble before reaching the halo gas, which could affect the early evolution of such jets.

  13. Spatially-Resolved Medium Resolution Spectroscopy of an Interacting E+A (post-starburst) System with the Subaru telescope

    Goto, Tomotsugu; Yagi, Masafumi; Yamauchi, Chisato

    2008-01-01

    We have performed a spatially-resolved medium resolution long-slit spectroscopy of a nearby E+A (post-starburst) galaxy system, SDSSJ161330.18+510335.5. This E+A galaxy has an obvious companion galaxy 14kpc in front with the velocity difference of 61.8 km/s. Both galaxies have obviously disturbed morphology We have found that H$\\delta$ equivalent width (EW) of the E+A galaxy is greater than 7\\AA galaxy wide (8.5 kpc). The E+A galaxy have a weak [OIII] emission (EW$\\sim$1\\AA) by $\\sim$2.6 kpc ...

  14. Hidden Starbursts and Active Galactic Nuclei at 0

    Lemaux, Brian C; Fèvre, Olivier Le; Ilbert, Olivier; Tresse, Laurence; Lubin, Lori M; Zamorani, Giovanni; Gal, Roy R; Ciliegi, Paolo; Cassata, Paolo; Kocevski, Dale D; McGrath, Elizabeth J; Bardelli, Sandro; Zucca, Elena; Squires, Gordon K

    2013-01-01

    We investigate of the properties of approximately 2000 Herschel/SPIRE-selected galaxies from 00.5), the highest LTIR galaxies in a given redshift bin are unobserved by SPIRE at subsequently lower redshifts, a trend linked to downsizing. In conjunction with other results, this evidence is used to argue for prevalent AGN-driven quenching in starburst galaxies across cosmic time.

  15. $^{13}CO(J = 1-0)$ Depression in Luminous Starburst Mergers

    Taniguchi, Y; Taniguchi, Yoshiaki; Ohyama, Youichi

    1998-01-01

    It is known that the class of luminous starburst galaxies tends to have higher $R =^{12}CO(J=1--0)/^{13}CO(J=1--0)$ integrated line intensity ratios ($R>20$) than normal spiral galaxies ($R \\sim 10$). Since most previous studies investigated only $R$, it remains uncertain whether the luminous starburst galaxies are overabundant in $^{12}$CO or underabundant in $^{13}$CO. Here we propose a new observational test to examine this problem. Our new test is to compare far-infrared luminosities [$L$(FIR)] with those of $^{12}$CO and $^{13}CO [L(^{12}CO)$ and $L(^{13}CO)$, respectively]. It is shown that there is a very tight correlation between $L(^{12}CO)$ and L(FIR), as found in many previous studies. However, we find that the $^{13}$CO luminosities of the high-R galaxies are lower by a factor of three on the average than those expected from the correlation for the remaining galaxies with ordinary $R$ values. Therefore, we conclude that the observed high $R$ values for the luminous starburst galaxies are attribute...

  16. Hubble Space Telescope Imaging of Post-Starburst Quasars

    Cales, S L; Shang, Zhaohui; Bennert, Vardha Nicola; Canalizo, G; Stoll, R; Ganguly, R; Berk, D Vanden; Paul, C; Diamond-Stanic, A

    2011-01-01

    We present images of 29 post-starburst quasars (PSQs) from a Hubble Space Telescope (\\emph{HST}) Advanced Camera for Surveys (ACS) Wide Field Channel Snapshot program. These broad-lined active galactic nuclei (AGN) possess the spectral signatures of massive ($M_{burst} \\sim 10^{10} M_{\\odot}$), moderate-aged stellar populations (hundreds of Myrs). Thus, their composite nature provides insight into the AGN-starburst connection. We measure quasar-to-host galaxy light contributions via semi-automated two-dimensional light profile fits of PSF-subtracted images. We examine the host morphologies, as well as, model the separate bulge and disk components. The \\emph{HST}/ACS-F606W images reveal an equal number of spiral (13/29) and early-type (13/29) hosts, with the remaining three hosts having indeterminate classifications. AGNs hosted by early-type galaxies have on average greater luminosity than those hosted by spiral galaxies. Disturbances, such as tidal tails, shells, star-forming knots, and asymmetries are seen ...

  17. Viscous time lags between starburst and AGN activity

    Blank, Marvin

    2016-01-01

    There is strong observational evidence indicating a time lag of order of some 100 Myr between the onset of starburst and AGN activity in galaxies. Dynamical time lags have been invoked to explain this. We extend this approach by introducing a viscous time lag the gas additionally needs to flow through the AGN's accretion disc before it reaches the central black hole. Our calculations reproduce the observed time lags and are in accordance with the observed correlation between black hole mass and stellar velocity dispersion.

  18. Cosmic Collisions: Galaxy Mergers and Evolution

    Trouille, Laura; Willett, Kyle; Masters, Karen; Lintott, Christopher; Whyte, Laura; Lynn, Stuart; Tremonti, Christina A.

    2014-08-01

    Over the years evidence has mounted for a significant mode of galaxy evolution via mergers. This process links gas-rich, spiral galaxies; starbursting galaxies; active galactic nuclei (AGN); post-starburst galaxies; and gas-poor, elliptical galaxies, as objects representing different phases of major galaxy mergers. The post-starburst phase is particularly interesting because nearly every galaxy that evolves from star-forming to quiescent must pass through it. In essence, this phase is a sort of galaxy evolution “bottleneck” that indicates that a galaxy is actively evolving through important physical transitions. In this talk I will present the results from the ‘Galaxy Zoo Quench’ project - using post-starburst galaxies to place observational constraints on the role of mergers and AGN activity in quenching star formation. `Quench’ is the first fully collaborative research project with Zooniverse citizen scientists online; engaging the public in all phases of research, from classification to data analysis and discussion to writing the article and submission to a refereed journal.

  19. Galaxies at High Redshifts

    Yahil, A; Fernández-Soto, A

    1998-01-01

    Several conclusions have been reached over the last few years concerning high-redshift galaxies: (1) The excess of faint blue galaxies is due to dwarf galaxies. (2) Star formation peaks at redshifts z ~1-2. (3) It appears to occur piecemeal in any given galaxy and there is no evidence for starbursting throughout a large ~10 kpc galaxy. (4) There is significant and sharp diminution in the number of L* spiral galaxies at redshifts 1galaxies at redshifts 2.5galaxies in universes with larger volumes per unit redshift, i.e., open or lambda models, which have lower deceleration parameters.

  20. The Systematic Properties of the Warm Phase of Starburst-Driven Galactic Winds

    Heckman, Timothy M.; Alexandroff, Rachel M.; Borthakur, Sanchayeeta; Overzier, Roderik; Leitherer, Claus

    2015-08-01

    Using ultraviolet absorption lines, we analyze the systematic properties of the warm ionized phase of starburst-driven winds in a sample of 39 low-redshift objects that spans broad ranges in starburst and galaxy properties. Total column densities for the outflows are ˜1021 cm-2. The outflow velocity (vout) correlates only weakly with the galaxy stellar mass ({M}*), or circular velocity (vcir), but strongly with both SFR and SFR/area. The normalized outflow velocity ({v}{out}/{v}{cir}) correlates well with both SFR/area and SFR/{M}*. The estimated outflow rates of warm ionized gas (\\dot{M}) are ˜1-4 times the SFR, and the ratio \\dot{M}/{SFR} does not correlate with vout. We show that a model of a population of clouds accelerated by the combined forces of gravity and the momentum flux from the starburst matches the data. We find a threshold value for the ratio of the momentum flux supplied by the starburst to the critical momentum flux needed for the wind to overcome gravity acting on the clouds (Rcrit). For {R}{crit} \\gt 10 (strong-outflows) the outflow’s momentum flux is similar to the total momentum flux from the starburst and the outflow velocity exceeds the galaxy escape velocity. Neither of these is the case for the weak outflows ({R}{crit} \\lt 10). For the weak-outflows, the data severely disagree with many prescriptions in numerical simulations or semi-analytic models of galaxy evolution. The agreement is better for the strong outflows, and we advocate the use of Rcrit to guide future prescriptions.

  1. Modeling Small Stellar Populations Using Starburst99

    Vazquez, Gerardo Arturo; Leitherer, Claus

    2015-08-01

    Stellar populations synthesis models have proven to be excellent tools to learn about galaxy evolution. However, modeling small stellar populations (lower than 105 M⊙) has been an intriguing and continuous to be a field of intensive research. In this work, we have developed a new approach to form stars from clusters first, where massive stars are formed from fractions of mass of small stellar clusters. This new approximation is based on the empirical power law (mc-2) for the mass function of clusters between 20-1100 M⊙ found in recent years and the maximum stellar mass that can be formed in a cluster. Incorporating this new approach to form clusters has made us upgrade the way we integrate the stellar properties and the way that the isochrone is produced with a new technique. To produce the new models we have used the most recent version of Starburst99 that incorporates the most recent stellar evolution models with rotation. On the verge of solving nearby stellar populations and observing small stellar populations across the universe, this new approach brings a new scope on trying to disentangle the nature of hyper and supermassive stars in small stellar populations. In this work we present this new approach and the results when these models are applied to very energetic stellar populations such as the cluster in NGC 3603. Our most important result is that we have modeled the ionizing power of this cluster and some others by forming enough supermassive stars in a cluster of ~104 M⊙.

  2. Minor Merger Origin for the Circumnuclear Starburst in NGC 7742

    Mazzuca, L M; Knapen, J H; Veilleux, S; Swaters, R

    2006-01-01

    We present an emission-line diagnostic analysis of integral-field spectroscopic observations that cover the central kiloparsec of NGC 7742. This Sa galaxy hosts a spectacular nuclear starburst ring and nuclear regions characterized by low-ionization emission. The gas in the ring rotates in the opposite sense to the stars in the galaxy, suggesting a recent merging or acquisition event. The combination of integral-field measurements for the H-alpha + [NII] emission lines from DensePak and the H-beta and [OIII] emission from Sauron allow the construction of diagnostic diagrams that highlight the transition from star formation in the nuclear ring to excitation by high-velocity shocks or by a central AGN towards the center. DensePak measurements for the [SII] line ratio reveal very low gas densities in the nuclear ring, Ne < 100 per cm^3, characteristic of massive HII regions. Comparison with MAPPINGS III models for starbursts with low gas densities show that the ring is of roughly solar metallicity. This sugge...

  3. Herschel-ATLAS: a binary HyLIRG pinpointing a cluster of starbursting proto-ellipticals

    Ivison, R J; Smail, Ian; Harris, A I; Bussmann, R S; Cooray, A; Cox, P; Fu, Hai; Kovacs, A; Krips, M; Narayanan, D; Negrello, M; Neri, R; Penarrubia, J; Richard, J; Riechers, D A; Rowlands, K; Staguhn, J G; Targett, T A; Amber, S; Baker, A J; Bourne, N; Bertoldi, F; Bremer, M; Calanog, J A; Clements, D L; Dannerbauer, H; Dariush, A; De Zotti, G; Dunne, L; Eales, S A; Farrah, D; Fleuren, S; Franceschini, A; Geach, J E; George, R D; Helly, J C; Hopwood, R; Ibar, E; Jarvis, M J; Kneib, J -P; Maddox, S; Omont, A; Scott, D; Serjeant, S; Smith, M W L; Thompson, M A; Valiante, E; Valtchanov, I; Vieira, J; van der Werf, P

    2013-01-01

    Exploiting the relationship between CO luminosity and line width determined for fainter starbursts, we identify and remove lensed sources from the widest Herschel extragalactic imaging survey to yield a sample of intrinsically luminous galaxies. Panchromatic observations of the best candidate HyLIRG then led to the discovery of at least four luminous galaxies across a ~100-kpc region at z=2.41. Our technique separates HyLIRGs from the more numerous, strongly lensed population, and can also pinpoint clusters of starbursting proto-ellipticals. Via sub-arcsecond interferometric imaging we have measured accurate gas and star-formation surface densities. The two brightest galaxies span ~3 kpc FWHM in submm/radio continuum and CO J=4-3, and double that in CO J=1-0. The broad CO line is due partly to the multitude of constituent galaxies and partly to large rotational velocities in two counter-rotating gas disks -- a scenario predicted to lead to the most intense starbursts, which will therefore come in pairs. The d...

  4. The Systematic Properties of the Warm Phase of Starburst-Driven Galactic Winds

    Heckman, Timothy M; Borthakur, Sanchayeeta; Overzier, Roderik; Leitherer, Claus

    2015-01-01

    Using ultra-violet absorption-lines, we analyze the systematic properties of the warm ionized phase of starburst-driven winds in a sample of 39 low-redshift objects that spans broad ranges in starburst and galaxy properties. Total column densities for the outflows are $\\sim$10$^{21}$ cm$^{-2}$. The outflow velocity (v$_{out}$) correlates only weakly with the galaxy stellar mass (M$_*$), or circular velocity (v$_{cir}$), but strongly with both SFR and SFR/area. The normalized outflow velocity (v$_{out}/v_{cir}$) correlates well with both SFR/area and SFR/M$_*$. The estimated outflow rates of warm ionized gas ($\\dot{M}$) are $\\sim$ 1 to 4 times the SFR, and the ratio $\\dot{M}/SFR$ does not correlate with v$_{out}$. We show that a model of a population of clouds accelerated by the combined forces of gravity and the momentum flux from the starburst matches the data. We find a threshold value for the ratio of the momentum flux supplied by the starburst to the critical momentum flux needed for the wind to overcome ...

  5. $^{13}CO(J=1-0)$ Depression in Luminous Starburst Mergers, Revisited

    Taniguchi, Y; Sanders, D B; Taniguchi, Yoshiaki; Ohyama, Youichi

    1999-01-01

    It is known that merging galaxies with luminous starbursts and high far-infrared luminosities tend to have higher $R_{1-0} =^{12}CO(J=1-0)/^{13}CO(J=1-0)$ integrated line intensity ratios ($R_{1-0} far-infrared luminosities [L(FIR)] with those of ^{12}CO(J=1-0) and ^{13}CO(J=1-0) for a sample of normal and starburst galaxies, Taniguchi & Ohyama found that the observed high $R_{1-0}$ values for the luminous starburst mergers are attributed to their lower ^{13}CO line intensities by a factor of 3 on the average. They suggested the following two possibilities; in the luminous starburst mergers, 1) ^{13}CO is underabundant with respect to ^{12}CO, or 2) exitation and/or optical depth effects are responsible for the change in $R_{1-0}$. In this paper, we investigate the second possibility using higher transition data of both ^{12}CO and ^{13}CO emission lines. Applying the same method proposed by Taniguchi & Ohyama to both ^{12}CO(J=2-1) and ^{13}CO(J=2-1), we find that ^{13}CO(J=2-1) is also depressed wit...

  6. Cold dust and young starbursts: spectral energy distributions of Herschel SPIRE sources from the HerMES survey

    Rowan-Robinson, Michael

    2015-01-01

    We present spectral energy distributions (SEDs) for 68 Herschel sources detected at 5-sigma at 250, 350 and 500 mu in the HerMES SWIRE-Lockman field. We explore whether existing models for starbursts, quiescent star-forming galaxies and for AGN dust tori are able to model the full range of SEDs measured with Herschel. We find that while many galaxies (~ 56 %) are well fitted with the templates used to fit IRAS, ISO and Spitzer sources, for about half the galaxies two new templates are required: quiescent ('cirrus') models with colder (10-20 K) dust, and a young starburst model with higher optical depth than Arp 220. Predictions of submillimetre fluxes based on model fits to 4.5-24 mu data agree rather poorly with the observed fluxes, but the agreement is better for fits to 4.5-70 mu data. Herschel galaxies detected at 500 mu tend to be those with the very highest dust masses.

  7. RADIO AND MID-INFRARED PROPERTIES OF COMPACT STARBURSTS: DISTANCING THEMSELVES FROM THE MAIN SEQUENCE

    We investigate the relationship between 8.44 GHz brightness temperatures and 1.4 to 8.44 GHz radio spectral indices with 6.2 μm polycyclic aromatic hydrocarbon (PAH) emission and 9.7 μm silicate absorption features for a sample of 36 local luminous and ultraluminous infrared galaxies. We find that galaxies having small 6.2 μm PAH equivalent widths (EQWs), which signal the presence of weak PAH emission and/or an excess of very hot dust, also have flat spectral indices. The three active galactic nuclei (AGN) identified through their excessively large 8.44 GHz brightness temperatures are also identified as AGN via their small 6.2 μm PAH EQWs. We also find that the flattening of the radio spectrum increases with increasing silicate optical depth, 8.44 GHz brightness temperature, and decreasing size of the radio source even after removing potential AGN, supporting the idea that compact starbursts show spectral flattening as the result of increased free-free absorption. These correlations additionally suggest that the dust obscuration in these galaxies must largely be coming from the vicinity of the compact starburst itself, and is not distributed throughout the (foreground) disk of the galaxy. Finally, we investigate the location of these infrared-bright systems relative to the main sequence (star formation rate versus stellar mass) of star-forming galaxies in the local universe. We find that the radio spectral indices of galaxies flatten with increasing distance above the main sequence, or in other words, with increasing specific star formation rate. This indicates that galaxies located above the main sequence, having high specific star formation rates, are typically compact starbursts hosting deeply embedded star formation that becomes more optically thick in the radio and infrared with increased distance above the main sequence.

  8. Symbiotic starburst-black hole AGN; 1, Isothermal hydrodynamics of the mass-loaded ISM

    Williams, R J R; Perry, J J

    1999-01-01

    Compelling evidence associates the nuclei of active galaxies and massive starbursts. The symbiosis between a compact nuclear starburst stellar cluster and a massive black hole can self-consistently explain the properties of active nuclei. The young stellar cluster has a profound effect on the most important observable properties of active galaxies through its gravity, and by mass injection through stellar winds, supernovae and stellar collisions. Mass injection generates a nuclear ISM which flows under gravitational and radiative forces until it leaves the nucleus or is accreted onto the black hole or accretion disc. The radiative force exerted by the black hole--accretion disc radiation field is not spherically symmetric. This results in complex flows in which regions of inflow can coexist with high Mach number outflowing winds and hydrodynamic jets. We present two-dimensional hydrodynamic models of such nISM flows, which are highly complex and time variable. Shocked shells, jets and explosive bubbles are pr...

  9. The Starburst-AGN connection: quenching the fire and feeding the monster

    Melnick, Jorge; Telles, Eduardo; De Propris, Roberto; Chu, Zhang-Hu

    2015-10-01

    The merger of two spiral galaxies is believed to be one of the main channels for the production of elliptical and early-type galaxies. In the process, the system becomes an (ultra) luminous infrared galaxy, or (U)LIRG, that morphs to a quasar, to a K+A galaxy, and finally to an early-type galaxy. The time scales for this metamorphosis are only loosely constrained by observations. In particular, the K+A phase should follow immediately after the quasi stellar object (QSO) phase during which the dust and gas remaining from the (U)LIRG phase are expelled by the active galactic nucleus (AGN). An intermediate class of QSOs with K+A spectral signatures, the post-starburst QSOs (PSQ), may represent the transitional phase between QSOs and K+As. We have compiled a sample of 72 bona fide z history of PSQ.

  10. Starburst-driven Galactic Superbubbles Radiating to 10 K

    Tanner, Ryan; Cecil, Gerald; Heitsch, Fabian

    2016-04-01

    Our three-dimensional hydrodynamical simulations of starbursts examine the formation of superbubbles over a range of driving luminosities and mass loadings that determine superbubble growth and wind velocity. From this we determine the relationship between the velocity of a galactic wind (GW) and the power of the starburst. We find a threshold for the formation of a wind, above which the speed of the wind is not affected by grid resolution or the temperature floor of our radiative cooling. We investigate the effect that two different temperature floors in our radiative cooling prescription have on wind kinematics and content. We find that cooling to 10 K instead of to 104 K increases the mass fraction of cold neutral and hot X-ray gas in the GW, while halving that in warm Hα. Our simulations show that the mass of cold gas transported into the lower halo does not depend on the starburst strength. Optically bright filaments form at the edge of merging superbubbles, or where a cold dense cloud has been disrupted by the wind. Filaments formed by merging superbubbles will persist and grow to \\gt 400 pc in length if anchored to a star forming complex. Filaments embedded in the hot GW contain warm and cold gas that moves 300‑1200 km s‑1 slower than the surrounding wind, with the coldest gas hardly moving with respect to the Galaxy. Warm and cold matter in the GW show asymmetric absorption profiles consistent with observations, with a thin tail up to the wind velocity.

  11. The Properties of Post-Starburst Quasars Based on Optical Spectroscopy

    Cales, Sabrina L.; Brotherton, Michael S.; Shang, Zhaohui; Runnoe, Jessie C.; DiPompeo, Michael A.; Bennert, Vardha Nicola; Canalizo, Gabriela; Hiner, Kyle D.; Stoll, R.; Ganguly, Rajib; Diamond-Stanic, Aleksandar

    2012-01-01

    We present optical spectroscopy of a sample of 38 post-starburst quasars (PSQs) at z ~ 0.3, 29 of which have morphological classifications based on Hubble Space Telescope imaging. These broad-lined active galactic nuclei (AGNs) possess the spectral signatures of massive intermediate-aged stellar populations making them potentially useful for studying connections between nuclear activity and host galaxy evolution. We model the spectra in order to determine the ages and masses of the host stell...

  12. Different star formation laws for disks versus starbursts at low and high redshifts

    Daddi, E; Walter, F; Bournaud, F; Salmi, F; Carilli, C; Dannerbauer, H; Dickinson, M; Monaco, P; Riechers, D

    2010-01-01

    We present evidence that 'bona fide' disks and starburst systems occupy distinct regions in the gas mass versus star formation (SF) rate plane, both for the integrated quantities and for the respective surface densities. This result is based on CO observations of galaxy populations at low and high redshifts, and on the current consensus for the CO luminosity to gas mass conversion factors. The data suggest the existence of two different star formation regimes: a long-lasting mode for disks and a more rapid mode for starbursts, the latter probably occurring during major mergers or in dense nuclear SF regions. Both modes are observable over a large range of SF rates. The detection of CO emission from distant near-IR selected galaxies reveals such bimodal behavior for the first time, as they allow us to probe gas in disk galaxies with much higher SF rates than are seen locally. The different regimes can potentially be interpreted as the effect of a top-heavy IMF in starbursts. However, we favor a different physi...

  13. Zooming in on major mergers: dense, starbursting gas in cosmological simulations

    Sparre, Martin

    2016-01-01

    We introduce the `Illustris zoom simulation project', which allows the study of selected galaxies forming in the $\\Lambda$CDM cosmology with a 40 times better mass resolution than in the parent large-scale hydrodynamical Illustris simulation. We here focus on the starburst properties of the gas in four cosmological simulations of major mergers. The galaxies in our high-resolution zoom runs exhibit a bursty mode of star formation with gas consumption timescales 10 times shorter than for the normal star formation mode. The strong bursts are only present in the simulations with the highest resolution, hinting that a too low resolution is the reason why the original Illustris simulation showed a dearth of starburst galaxies. Very pronounced bursts of star formation occur in two out of four major mergers we study. The high star formation rates, the short gas consumption timescales and the morphology of these systems strongly resemble observed nuclear starbursts. This is the first time that a sample of major merger...

  14. LUMINOUS STAR-FORMING GALAXIES IN THE GALAXY EVOLUTION EXPLORER-SLOAN DIGITAL SKY SURVEY DATABASE

    We have a Galaxy Evolution Explorer-Sloan Digital Sky Survey sample that isolates intermediate redshift QSOs. Some 1% of the spectroscopic sample consists of galaxies in starburst or post-starburst stages. We discuss the most luminous 10 of these, which have redshifts between 0.18 and 0.6. We present spectroscopic measures and derive star formation rates. Two of the six with Mg II coverage reveal outflows in this line. None shows any sign of active galactic nucleus activity. We discuss their star formation histories and their place in galaxy evolution.

  15. Chemical Enrichment from Massive Stars in Starbursts; 2, NGC 1569

    Kobulnicky, H A; Kobulnicky, Henry A.; Skillman, Evan D.

    1997-01-01

    We present a longslit optical spectrophotometric survey in the irregular "post-starburst" galaxy NGC 1569 to search for chemical gradients and inhomogeneities in the interstellar medium. Despite the presence of two massive evolved starclusters and numerous HII regions, we find no evidence for chemical gradients or inhomogeneities that may be attributed to enrichment from the recent star formation activity. The chemical properties are consistent with 12+log(O/H)=8.19+/-0.04 and log(N/O)=-1.40+/-0.05 at all locations. No localized chemical self-enrichment ("pollution") from massive star evolution is found, even though the data are sensitive to the chemical yields from as few as two or three massive stars. Flat chemical abundance profiles appear to be the rule rather than the exception in low-mass galaxies. Strong chemical signatures in the surrounding interstellar material should be detected unless one or more of the following are true: 1) Different star forming regions throughout the studied galaxies ``conspir...

  16. The multiphase starburst-driven galactic wind in NGC 5394

    Martín-Fernández, P; Zurita, A; Mediavilla, E; Castillo-Morales, A

    2016-01-01

    We present a detailed study of the neutral and ionised gas phases in the galactic wind for the nearby starburst galaxy NGC 5394 based on new integral field spectroscopy obtained with the INTEGRAL fibre system at the William Herschel Telescope. The neutral gas phase in the wind is detected via the interstellar NaI D doublet absorption. After a careful removal of the stellar contribution to these lines, a significant amount of neutral gas (~10^7 Msun) is detected in a central region of ~1.75 kpc size. This neutral gas is blueshifted by ~165 km/s with respect to the underlying galaxy. The mass outflow of neutral gas is comparable to the star formation rate of the host galaxy. Simultaneously, several emission lines (Ha, [NII], [SII]) are also analysed looking for the ionised warm phase counterpart of the wind. A careful kinematic decomposition of the line profiles reveals the presence of a secondary, broader, kinematic component. This component is found roughly in the same region where the NaI D absorption is det...

  17. Empirical ugri-UBVRc Transformations for Galaxies

    Cook, David O; Johnson, Benjamin D; Van Zee, Liese; Lee, Janice C; Kennicutt, Robert C; Calzetti, Daniela; Staudaher, Shawn M; Engelbracht, Charles W

    2014-01-01

    We present empirical color transformations between Sloan Digital Sky Survey ugri and Johnson-Cousins UBVRc photometry for nearby galaxies (D < 11 Mpc). We use the Local Volume Legacy (LVL) galaxy sample where there are 90 galaxies with overlapping observational coverage for these two filter sets. The LVL galaxy sample consists of normal, non-starbursting galaxies. We also examine how well the LVL galaxy colors are described by previous transformations derived from standard calibration stars and model-based galaxy templates. We find significant galaxy color scatter around most of the previous transformation relationships. In addition, the previous transformations show systematic offsets between transformed and observed galaxy colors which are visible in observed color-color trends. The LVL-based $galaxy$ transformations show no systematic color offsets and reproduce the observed color-color galaxy trends.

  18. Gamma-Ray Dominated Regions: Extending the Reach of Cosmic Ray Ionization in Starburst Environments

    Lacki, Brian C

    2012-01-01

    Cosmic rays are appealing as a source of ionization in starburst galaxies because of the great columns they can penetrate, but in the densest regions of starbursts, they may be stopped by pion production and ionization energy losses. I argue that gamma rays are the source of ionization in the deepest molecular clouds of dense starbursts, creating Gamma-Ray Dominated Regions (GRDRs). Gamma rays are not deflected by magnetic fields, have a luminosity up to ~1/3 that of the injected cosmic rays, and can easily penetrate column depths of ~100 g/cm^2 before being attenuated by gamma-Z pair production. The ionization rates of GRDRs, <~10^-16 s^-1, are much smaller than in cosmic ray dominated regions, but in the most extreme starbursts, they may still reach values comparable to those in Milky Way molecular clouds. The gas temperatures in GRDRs could be likewise low, <~10 K if there is no additional heating from dust or turbulence, while at high densities, the kinetic temperature will approach the dust tempera...

  19. Molecular outflows in starburst nuclei

    Roy, Arpita; Sharma, Prateek; Shchekinov, Yuri

    2016-01-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with $N_{OB}\\ge 10^5$ (corresponding to a star formation rate (SFR)$\\ge 1$ M$_{\\odot}$ yr$^{-1}$ in the nuclear region), in a stratified disk with mid-plane density $n_0\\sim 200\\hbox{--}1000$ cm$^{-3}$ and scale height $z_0\\ge 200 (n_0/10^2 \\, {\\rm cm}^{-3})^{-3/5}$ pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is $\\ge 10^7$ M$_\\odot$ at a distance of a few hundred pc, with a speed of several tens of km s$^{-1}$. We show that a SFR surface density of $10 \\le \\Sigma_{SFR} \\le 50$ M$_\\odot$ yr$^{-1}$ kpc$^{-2}$ favours the production of molecular outflows, consistent with observed values.

  20. Molecular outflows in starburst nuclei

    Roy, Arpita; Nath, Biman B.; Sharma, Prateek; Shchekinov, Yuri

    2016-08-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with NOB ≥ 105 (corresponding to a star formation rate (SFR)≥1 M⊙ yr-1 in the nuclear region), in a stratified disk with mid-plane density n0 ˜ 200-1000 cm-3 and scale height z0 ≥ 200(n0/102 cm-3)-3/5 pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is ≥107 M⊙ at a distance of a few hundred pc, with a speed of several tens of km s-1. We show that a SFR surface density of 10 ≤ ΣSFR ≤ 50 M⊙ yr-1 kpc-2 favours the production of molecular outflows, consistent with observed values.

  1. Symposium “Mapping the Galaxy and Nearby Galaxies”

    Wada, Keiichi; ASTROPHYSICS AND SPACE SCIENCE PROCEEDINGS

    2008-01-01

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

  2. Shape asymmetry: a morphological indicator for automatic detection of galaxies in the post-coalescence merger stages

    Pawlik, M M; Walcher, C J; Johansson, P H; Villforth, C; Rowlands, K; Mendez-Abreu, J; Hewlett, T

    2015-01-01

    We present a new morphological indicator designed for automated recognition of galaxies with faint asymmetric tidal features suggestive of an ongoing or past merger. We use this new indicator, together with preexisting diagnostics of galaxy structure to study the role of galaxy mergers in inducing (post-)starburst spectral signatures in local galaxies, and investigate whether (post-)starburst galaxies play a role in the build up of the `red sequence'. Our morphological and structural analysis of an evolutionary sample of 335 (post-)starburst galaxies in the SDSS DR7 with starburst ages 0galaxies with young starbursts (tSB<0.1 Gyr) show signatures of an ongoing or past merger. This fraction declines with starburst age, and we find a good agreement between automated and visual classifications. The majority of the oldest (post-)starburst galaxies in our sample (tSB~0.6Gyr) have structural properties characteristic of early-type disks and are not as highly concentrated as ...

  3. Submillimeter galaxies as progenitors of compact quiescent galaxies

    Three billion years after the big bang (at redshift z = 2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation and extremely compact with stellar mass densities at least an order of magnitude larger than in low-redshift ellipticals, their descendants. Little is known about how they formed, but their evolved, dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr earlier (at 3 < z < 6). Simulations show that gas-rich major mergers can give rise to such starbursts, which produce dense remnants. Submillimeter-selected galaxies (SMGs) are prime examples of intense, gas-rich starbursts. With a new, representative spectroscopic sample of compact, quiescent galaxies at z = 2 and a statistically well-understood sample of SMGs, we show that z = 3-6 SMGs are consistent with being the progenitors of z = 2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses, and internal velocities. Assuming an evolutionary connection, their space densities also match if the mean duty cycle of SMG starbursts is 42−29+40 Myr (consistent with independent estimates), which indicates that the bulk of stars in these massive galaxies were formed in a major, early surge of star formation. These results suggest a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent star formation through their appearance as high stellar-density galaxy cores and to their ultimate fate as giant ellipticals.

  4. ALFALFA Hα Reveals How Galaxies Use their HI Fuel

    Jaskot, Anne; Oey, Sally; Salzer, John; Van Sistine, Angela; Bell, Eric; Haynes, Martha

    2015-08-01

    Atomic hydrogen traces the raw material from which molecular clouds and stars form. With the ALFALFA Hα survey, a statistically complete subset of the ALFALFA survey, we examine the processes that affect galaxies’ abilities to access and consume their HI gas. On galaxy-wide scales, HI gas fractions correlate only weakly with instantaneous specific star formation rates (sSFRs) but tightly with galaxy color. We show that a connection between dust and HI content, arising from the fundamental mass-metallicity-HI relation, leads to this tight color correlation. We find that disk galaxies follow a relation between stellar surface density and HI depletion time, consistent with a scenario in which higher mid-plane pressure leads to more efficient molecular cloud formation from HI. In contrast, spheroids show no such trend. Starbursts, identified by Hα equivalent width, do not show enhanced HI gas fractions relative to similar mass non-starburst galaxies. The starbursts’ shorter HI depletion times indicate more efficient consumption of HI, and galaxy interactions drive this enhanced star formation efficiency in several starbursts. Interestingly, the most disturbed starbursts show greater enhancements in HI gas fraction, which may indicate an excess of HI at early merger stages. At low galaxy stellar masses, the triggering mechanism for starbursts is less clear; the high scatter in efficiency and sSFR among low-mass galaxies may result from periodic bursts. We find no evidence for depleted HI reservoirs in starbursts, which suggests that galaxies may maintain sufficient HI to fuel multiple starburst episodes.

  5. The Evolution of Galaxies in Compact Groups

    Coziol, R; Capelato, H V; Ribeiro, A L B; Coziol, Roger; Carvalho, Reinaldo R. de; Capelato, Hugo V.; Ribeiro, Andre L. B.

    1998-01-01

    We present the analysis of the spectra of 62 galaxies in 15 compact groups. The galaxies were classified in four activity classes: galaxies without emission, starburst nucleus galaxies (SBNGs), luminous AGNs and low-luminosity AGNs (LLAGNs). The star formation in the HCG starbursts is more intense than in normal spirals, but comparable to those in the field SBNGs. Their mean gas metallicity is solar and they do not follow the metallicity-luminosity relation traced by the early-type SBNGs in the field, suggesting that most of them are late-type SBNGs. This morphology preference coupled to the observation that the HCG starbursts are predominantly in the halo of the groups is consistent with the idea that compact groups are embedded in sparser structures. The stellar metallicities of the non starburst galaxies are relatively high for their luminosities. In these galaxies the equivalent widths of the metal absorption lines are slightly narrower than normal while the Balmer absorption lines are relatively strong. ...

  6. The Fossil Starburst in M82

    De Grijs, R; Gallagher, J S; Grijs, Richard de; Connell, Robert W. O'; III, John S. Gallagher

    1999-01-01

    We present high-resolution optical and near-infrared HST observations of two adjacent regions in the fossil starburst region in M82, M82 B1 and B2. The presence of both the active and the fossil starburst in M82 provides a unique physical environment to study the stellar and dynamical evolution of star cluster systems. The cluster population in B2 is more heavily affected by internal extinction than that in B1, amounting to an excess extinction in B2 of A_(V,excess) = 1.1 +/- 0.3 mag. Preliminary age estimates date the cluster population in the fossil starburst between ~2 x 10^8 and ~10^9 years. The radial luminosity profiles of the brightest clusters are more closely approximated by power laws than by a Gaussian model, in particular in their wings, which favors a slow star formation scenario.

  7. The multiphase starburst-driven galactic wind in NGC 5394

    Martín-Fernández, Pablo; Jiménez-Vicente, Jorge; Zurita, Almudena; Mediavilla, Evencio; Castillo-Morales, África

    2016-05-01

    We present a detailed study of the neutral and ionised gas phases in the galactic wind for the nearby starburst galaxy NGC 5394 based on new integral field spectroscopy obtained with the INTEGRAL fibre system at the William Herschel Telescope. The neutral gas phase in the wind is detected via the interstellar Na I D doublet absorption. After a careful removal of the stellar contribution to these lines, a significant amount of neutral gas (˜107 M⊙) is detected in a central region of ˜1.75 kpc size. This neutral gas is blueshifted by ˜165 km s-1 with respect to the underlying galaxy. The mass outflow of neutral gas is comparable to the star formation rate of the host galaxy. Simultaneously, several emission lines (Hα, [N II], [S II]) are also analysed looking for the ionised warm phase counterpart of the wind. A careful kinematic decomposition of the line profiles reveals the presence of a secondary, broader, kinematic component. This component is found roughly in the same region where the Na I D absorption is detected. It presents higher [N II]/Hα and [S II]/Hα line ratios than the narrow component at the same locations, indicative of contamination by shock ionization. This secondary component also presents blueshifted velocities, although smaller than those measured for the neutral gas, averaging to ˜-30 km s-1. The mass and mass outflow rate of the wind is dominated by the neutral gas, of which a small fraction might be able to escape the gravitational potential of the host galaxy. The observations in this system can be readily understood within a bipolar gas flow scenario.

  8. Young star clusters: Metallicity tracers in external galaxies

    Anders, P.; Alvensleben, U. Fritze--v.; de Grijs, R.

    2003-01-01

    Star cluster formation is a major mode of star formation in the extreme conditions of interacting galaxies and violent starbursts. These newly-formed clusters are built from recycled gas, pre-enriched to various levels within the interacting galaxies. Hence, star clusters of different ages represent a fossil record of the chemical enrichment history of their host galaxy, as well as of the host galaxy's violent star formation history. We present a new set of evolutionary synthesis models of ou...

  9. Scaling relations of metallicity, stellar mass, and star formation rate in metal-poor starbursts: I. A fundamental plane

    Hunt, Leslie; Galli, Daniele; Schneider, Raffaella; Bianchi, Simone; Maiolino, Roberto; Romano, Donatella; Tosi, Monica; Valiante, Rosa

    2012-01-01

    Most galaxies follow well-defined scaling relations of metallicity (O/H), star formation rate (SFR), and stellar mass. However, low-metallicity starbursts, rare in the Local Universe but more common at high redshift, deviate significantly from these scaling relations. On the "main sequence" of star formation, these galaxies have high SFR for a given M*; and on the mass-metallicity relation, they have excess M* for their low metallicity. In this paper, we characterize O/H, M*, and SFR for these deviant "low-metallicity starbursts", selected from a sample of ~1100 galaxies, spanning almost two orders of magnitude in metal abundance, a factor of ~10^6 in SFR, and of ~10^5 in stellar mass. Our sample includes quiescent star-forming galaxies and blue compact dwarfs at redshift 0, luminous compact galaxies at redshift 0.3, and Lyman Break galaxies at redshifts 1-3.4. Applying a Principal Component Analysis (PCA) to the galaxies in our sample with M*<10^{10} Msun gives a Fundamental Plane (FP) of scaling relation...

  10. The colours of HII galaxies

    Telles, E; Telles, Eduardo; Terlevich, Roberto

    1995-01-01

    We present high spatial resolution CCD surface photometry study in the optical V, R and I filters of 15 HII galaxies from the Nordic Optical Telescope and the Jacobus Kapteyn Telescope at Canary Islands. The colours of the starburst continuum and of the underlying galaxy are measured. The distribution of colours of the underlying galaxy in HII galaxies is similar to the colours of other late type low surface brightness galaxies which suggests a close kinship of these with the quiescent phases of HII galaxies. However, comparison with recent evolutionary population synthesis models show that the observational errors and the uncertainties in the models are still too large to put strict constraints on their past star formation history.

  11. Sub-millimeter galaxies as progenitors of compact quiescent galaxies

    Toft, S; Magnelli, B; Karim, A; Zirm, A; Michalowski, M; Capak, P; Sheth, K; Schawinski, K; Krogager, J -K; Wuyts, S; Sanders, D; Man, A W S; Lutz, D; Staguhn, J; Berta, S; Mccracken, H; Krpan, J; Riechers, D

    2014-01-01

    Three billion years after the big bang (at redshift z=2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation and extremely compact with stellar mass densities at least an order of magnitude larger than in low redshift ellipticals, their descendants. Little is known about how they formed, but their evolved, dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr earlier (at 3starbursts which produce dense remnants. Sub-millimeter selected galaxies (SMGs) are prime examples of intense, gas-rich, starbursts. With a new, representative spectroscopic sample of compact quiescent galaxies at z=2 and a statistically well-understood sample of SMGs, we show that z=3-6 SMGs are consistent with being the progenitors of z=2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses and internal velocities. As...

  12. BLACK-HOLE-BULGE RELATIONSHIP OF POST-STARBURST QUASARS AT z ∼ 0.3

    The MBH-σ* relation has been studied extensively for local galaxies, but to date there have been scarce few direct measurements of stellar velocity dispersions for systems beyond the local universe. We investigate black hole and host galaxy properties of six 'post-starburst quasars' (PSQs) at z ∼ 0.3. Spectra of these objects simultaneously display features from the active nucleus including broad emission lines and a host galaxy Balmer absorption series indicative of the post-starburst stellar population. These are the first measurements of σ* in such objects, and we significantly increase the number of directly measured non-local objects on the MBH-σ* diagram. The 'PSQs' of our sample fall on or above the locally defined MBH-σ* relation, a result that is consistent with previous MBH-σ* studies of samples at z > 0.1. However, they are generally consistent with the MBH-Lbulge relation. Furthermore, their location on the Faber-Jackson relation suggests that some of the bulges may be dynamically peculiar.

  13. Warm-Dense Molecular Gas in the ISM of Starbursts, LIRGs and ULIRGs

    Narayanan, D; Groppi, C E; Narayanan, Desika; Walker, Christopher K.; Groppi, Christopher E.

    2005-01-01

    The role of star formation in luminous and ultraluminous infrared galaxies is a hotly debated issue: while it is clear that starbursts play a large role in powering the IR luminosity in these galaxies, the relative importance of possible enshrouded AGNs is unknown. It is therefore important to better understand the role of star forming gas in contributing to the infrared luminosity in IR-bright galaxies. The J=3 level of 12CO lies 33K above ground and has a critical density of ~1.5 X 10^4 cm^-3. The 12CO(J=3-2) line serves as an effective tracer for warm-dense molecular gas heated by active star formation. Here we report on 12CO (J=3-2) observations of 17 starburst spirals, LIRGs and ULIRGs which we obtained with the Heinrich Hertz Submillimeter Telescope on Mt. Graham, Arizona. Our main results are the following: 1. We find a nearly linear relation between the infrared luminosity and warm-dense molecular gas such that the infrared luminosity increases as the warm-dense molecular gas to the power 0.92; We int...

  14. The Panchromatic STARBurst IRregular Dwarf Survey (STARBIRDS): Observations and Data Archive

    McQuinn, Kristen B. W.; Mitchell, Noah P.; Skillman, Evan D.

    2015-06-01

    Understanding star formation in resolved low mass systems requires the integration of information obtained from observations at different wavelengths. We have combined new and archival multi-wavelength observations on a set of 20 nearby starburst and post-starburst dwarf galaxies to create a data archive of calibrated, homogeneously reduced images. Named the panchromatic “STARBurst IRregular Dwarf Survey” archive, the data are publicly accessible through the Mikulski Archive for Space Telescopes. This first release of the archive includes images from the Galaxy Evolution Explorer Telescope (GALEX), the Hubble Space Telescope (HST), and the Spitzer Space Telescope (Spitzer) Multiband Imaging Photometer instrument. The data sets include flux calibrated, background subtracted images, that are registered to the same world coordinate system. Additionally, a set of images are available that are all cropped to match the HST field of view. The GALEX and Spitzer images are available with foreground and background contamination masked. Larger GALEX images extending to 4 times the optical extent of the galaxies are also available. Finally, HST images convolved with a 5″ point spread function and rebinned to the larger pixel scale of the GALEX and Spitzer 24 μm images are provided. Future additions are planned that will include data at other wavelengths such as Spitzer IRAC, ground-based Hα, Chandra X-ray, and Green Bank Telescope H i imaging. Based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA), and the Canadian Astronomy Data Centre (CADC/NRC/CSA).

  15. THE PROPERTIES OF POST-STARBURST QUASARS BASED ON OPTICAL SPECTROSCOPY

    Cales, Sabrina L. [Departamento de Astronomia, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Brotherton, Michael S.; Shang, Zhaohui; Runnoe, Jessie C.; DiPompeo, Michael A., E-mail: scales@astro-udec.cl, E-mail: scales@uwyo.edu, E-mail: mbrother@uwyo.edu, E-mail: shang@uwyo.edu, E-mail: jrunnoe@uwyo.edu, E-mail: mdipompe@uwyo.edu [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); and others

    2013-01-10

    We present optical spectroscopy of a sample of 38 post-starburst quasars (PSQs) at z {approx} 0.3, 29 of which have morphological classifications based on Hubble Space Telescope imaging. These broad-lined active galactic nuclei (AGNs) possess the spectral signatures of massive intermediate-aged stellar populations, making them potentially useful for studying connections between nuclear activity and host galaxy evolution. We model the spectra in order to determine the ages and masses of the host stellar populations, and the black hole masses and Eddington fractions of the AGNs. Our model components include an instantaneous starburst, a power law, and emission lines. We find that the PSQs have M {sub BH} {approx} 10{sup 8} M {sub Sun} accreting at a few percent of Eddington luminosity and host {approx}10{sup 10.5} M {sub Sun} stellar populations which are several hundred Myr to a few Gyr old. We investigate relationships among these derived properties, spectral properties, and morphologies. We find that PSQs hosted in spiral galaxies have significantly weaker AGN luminosities, older starburst ages, and narrow emission-line ratios diagnostic of ongoing star formation when compared to their early-type counterparts. We conclude that the early-type PSQs are likely the result of major mergers and were likely luminous infrared galaxies in the past, while spiral PSQs with more complex star formation histories are triggered by less dramatic events (e.g., harassment, bars). We provide diagnostics to distinguish the early-type and spiral hosts when high spatial resolution imaging is not available.

  16. Starburst Driven Thermal and Non-thermal Structures in the Galactic Center Region

    Yusef-Zadeh, F; Hewitt, J; Law, C; Maddalena, R; Roberts, D A

    2005-01-01

    We briefly review the prominent thermal and nonthermal sources near the Galactic center. These sources include the young stellar clusters, the Sgr B complex as well as the large-scale nonthermal filaments and lobes. Some of the recent radio images of this region based on VLA and Green Bank Telescope observations are also presented. We then argue that the origin of the large-scale features within the inner two degrees of the Galactic center is tied to a past starburst activity in the nucleus of the Galaxy.

  17. Far-infrared spectroscopy of a lensed starburst: a blind redshift from Herschel

    George, RD; Ivison, RJ; Hopwood, R.; Riechers, DA; Bussmann, RS; Cox, P.; Dye, S.; Krips, M.; Negrello, M.; Neri, R.; Serjeant, S; Valtchanov, I.; Baes, Maarten; Bourne, N.; Clements, DL

    2013-01-01

    We report the redshift of HATLAS J132427.0+284452 (hereafter HATLAS J132427), a gravitationally lensed starburst galaxy, the first determined 'blind' by the Herschel Space Observatory. This is achieved via the detection of [C II] consistent with z = 1.68 in a far-infrared spectrum taken with the SPIRE Fourier Transform Spectrometer (FTS). We demonstrate that the [C II] redshift is secure via detections of CO J = 2 -> 1 and 3 -> 2 using the Combined Array for Research in Millimeter-wave Astron...

  18. Dynamical Delays Between Starburst and AGN Activity in Galaxy Nuclei

    Hopkins, Philip F

    2011-01-01

    Observations of AGN have suggested a possible delay between the peak of star formation (on some scale) and AGN activity. Feedback from fast stellar winds has been invoked to explain this, but this is not likely to be viable in bright systems accreting primarily cold dense gas. We show that such a delay can arise even in bright quasars for purely dynamical reasons. If some large-scale process produces rapid inflow, smaller scales will quickly become gas-dominated. As the gas density peaks, so does the SFR. However, gravitational torques which govern further inflow are relatively inefficient in gas-dominated systems; as more gas is turned into stars, the stars provide an efficient angular momentum sink allowing more rapid inflow. Moreover, the gas provided to the central regions in mergers or strong disk instabilities will typically be ~100 times larger than that needed to fuel the BH; the system is effectively in the 'infinite gas supply' limit. BH growth can therefore continue for some time while the gas supp...

  19. ALMA observations of cool dust in a low-metallicity starburst, SBS0335-052

    Hunt, L K; Casasola, V; Garcia-Burillo, S; Combes, F; Nikutta, R; Caselli, P; Henkel, C; Maiolino, R; Menten, K M; Sauvage, M; Weiss, A

    2013-01-01

    We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 0 Band 7 observations of an extremely metal-poor dwarf starburst galaxy in the Local Universe, SBS0335-052 (12+log(O/H)~7.2). With these observations, dust is detected at 870micron (ALMA Band 7), but 87% of the flux in this band is due to free-free emission from the starburst. We have compiled a spectral energy distribution (SED) of SBS0335-052 that spans almost 6 orders of magnitude in wavelength and fit it with a spherical dust shell heated by a single-age stellar population; the best-fit model gives a dust mass of (3.8+/-0.6)x10^4 Msun. We have also constructed a SED including Herschel archival data for IZw18, another low-metallicity dwarf starburst (12+log(O/H)=7.17), and fit it with a similar model to obtain a dust mass of (3.4+/-1.0)x10^2 Msun. Compared with their atomic gas mass, the dust mass of SBS0335-052 far exceeds the prediction of a linear trend of dust-to-gas mass ratio with metallicity, while IZw18 falls far below. We use gas...

  20. Intrinsic viscosity of model starburst dendrimers

    The hydrodynamic radii (Rη) calculated from intrinsic viscosities of poly(amido amide) (PAMAM) starburst dendrimers increasing generation number. This would seem to support a structure with strongly stretched tiers, which is relatively hollow near the core, and with most end groups near the surface. However, a computer simulation due to Lescanec and Muthukumar supports a more folded structure with higher density near the core and with end groups dispersed throughout the molecule. Here we calculate the hydrodynamic radii of the Lescanec-Muthukumar model using intrinsic viscosity formulas developed by Zimm and Fixman. The Lescanec-Muthukumar starbursts with relatively stiff spacers have hydrodynamic radii in good agreement with the experimental PAMAM radii, in spite of their folded structure. The hydrodynamic radius is sensitive both to the molecular size and to the density. As the number of generations increases, the molecules become more dense and the hydrodynamic radius increases more rapidly than the radius of gyration. 16 refs., 7 figs., 2 tabs

  1. QSO variability: probing the Starburst model

    Aretxaga, Itziar; Fernandes Jr., R. Cid; Terlevich, R. J.

    1996-01-01

    The consistency of the Starburst model for AGN is tested using the optical variability observed in large data bases of QSOs. Theoretical predictions for the variability--luminosity relationship and structure function are presented and compared with observations. If QSOs follow a variability--wavelength relation as that observed in nearby AGN, the model proves successful in reproducing the main characteristics of optical variability. The wavelength dependence (1) flattens the, otherwise, monoc...

  2. The Starburst-AGN connection: quenching the fire and feeding the beast

    Melnick, Jorge; De Propris, Roberto; Zhang-Hu, Chu

    2015-01-01

    The merger of two spiral galaxies is believed to be one of the main channels for the production of elliptical and early-type galaxies. In the process, the system becomes an (ultra) luminous infrared galaxy, or (U)LIRG, that morphs to a quasar, to a K+A galaxy, and finally to an early-type galaxy. The time scales for this metamorphosis are only loosely constrained by observations. In particular, the K+A phase should follow immediately after the QSO phase during which the dust and gas remaining from the (U)LIRG phase are expelled by the AGN. An intermediate class of QSOs with K+A spectral signatures, the post-starburst QSOs or PSQ, may represent the transitional phase between QSOs and K+As. We have compiled a sample of 72 {bona fide} $z<0.5$ PSQ from the SDSS DR7 QSO catalogue. We find the intermediate age populations in this sample to be on average significantly weaker and metal poorer than their putative descendants, the K+A galaxies. The typical spectral energy distribution of PSQ is well fitted by three ...

  3. HERSCHEL-ATLAS: A BINARY HyLIRG PINPOINTING A CLUSTER OF STARBURSTING PROTOELLIPTICALS

    Ivison, R. J. [UK Astronomy Technology Centre, Science and Technology Facilities Council, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Swinbank, A. M.; Smail, Ian [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Harris, A. I. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Bussmann, R. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Cooray, A.; Fu, H. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Cox, P.; Krips, M.; Neri, R. [Institut de Radioastronomie Millimetrique, 300 rue de la Piscine, F-38406 Saint-Martin d' Heres (France); Kovacs, A. [Department of Astronomy, University of Minnesota, Minneapolis, MN 55414 (United States); Narayanan, D. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Negrello, M. [INAF, Osservatorio Astronomico di Padova, I-35122 Padova (Italy); Penarrubia, J.; Targett, T. A. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Richard, J. [Centre de Recherche Astrophysique de Lyon, Universite Lyon 1, 9 Avenue Charles Andre, F-69561 Saint Genis Laval Cedex (France); Riechers, D. A. [Department of Astronomy, Space Science Building, Cornell University, Ithaca, NY 14853-6801 (United States); Rowlands, K. [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Staguhn, J. G. [The Henry A. Rowland Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Amber, S. [Department of Physical Sciences, The Open University, Milton Keynes (United Kingdom); and others

    2013-08-01

    Panchromatic observations of the best candidate hyperluminous infrared galaxies from the widest Herschel extragalactic imaging survey have led to the discovery of at least four intrinsically luminous z = 2.41 galaxies across an Almost-Equal-To 100 kpc region-a cluster of starbursting protoellipticals. Via subarcsecond interferometric imaging we have measured accurate gas and star formation surface densities. The two brightest galaxies span {approx}3 kpc FWHM in submillimeter/radio continuum and CO J = 4-3, and double that in CO J = 1-0. The broad CO line is due partly to the multitude of constituent galaxies and partly to large rotational velocities in two counter-rotating gas disks-a scenario predicted to lead to the most intense starbursts, which will therefore come in pairs. The disks have M{sub dyn} of several Multiplication-Sign 10{sup 11} M{sub Sun }, and gas fractions of {approx}40%. Velocity dispersions are modest so the disks are unstable, potentially on scales commensurate with their radii: these galaxies are undergoing extreme bursts of star formation, not confined to their nuclei, at close to the Eddington limit. Their specific star formation rates place them {approx}> 5 Multiplication-Sign above the main sequence, which supposedly comprises large gas disks like these. Their high star formation efficiencies are difficult to reconcile with a simple volumetric star formation law. N-body and dark matter simulations suggest that this system is the progenitor of a B(inary)-type Almost-Equal-To 10{sup 14.6}-M{sub Sun} cluster.

  4. Gaseous Flows in Galaxies

    Combes, F

    2007-01-01

    The gas component plays a major role in the dynamics of spiral galaxies, because of its dissipative character, and its ability to exchange angular momentum with stars in the disk. Due to its small velocity dispersion, it triggers gravitational instabilities, and the corresponding non-axisymmetric patterns produce gravity torques, which mediate these angular momentum exchanges. When a srong bar pattern develops with the same pattern speed all over the disk, only gas inside corotation can flow towards the center. But strong bars are not long lived in presence of gas, and multiple-speed spiral patterns can develop between bar phases, and help the galaxy to accrete external gas flowing from cosmic filaments. The gas is then intermittently driven to the galaxy center, to form nuclear starbursts and fuel an active nucleus. The various time-scales of these gaseous flows are described.

  5. Slowly cooking galaxies

    Legrand, F

    1999-01-01

    Recent spectroscopic observations of IZw~18 have revealed homogeneous abundance throughout the galaxy and several observations of other starburst galaxies have shown no significant gradient or discontinuity in the abundance distributions within the HII regions. I thus concur with Tenorio-Tagle (1996) and Devost et al. (1997) that these observed abundance homogeneities cannot be produced by the material ejected from the stars formed in the current burst and result from a previous star formation episode. Metals ejected in the current burst of star formation remain most probably hidden in a hot phase and are undetectable using optical spectroscopy. Combining various observational facts, for instance the faint star formation rate observed in low surface brightness galaxies (van Zee et al., 1997), I propose that a low and continuous star formation rate occurring during quiescent phases between bursts is a non negligible source of new elements in the interstellar medium. Using a spectrophotometric and chemical evol...

  6. Magnetic Fields in Spiral Galaxies

    Beck, Rainer

    2015-01-01

    Radio synchrotron emission is a powerful tool to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30\\mu G) and in central starburst regions (50-100\\mu G). Such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. Polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. The strongest ordered fields (10-15\\mu G) are generally found in interarm regions. In galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies, and in central regions. Ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the interg...

  7. A compact starburst ring traced by clumpy OH megamaser emission

    Parra, R; Elitzur, M; Pihlström, Y M

    2005-01-01

    We model the OH megamaser emission from the luminous infrared galaxy IIIZw35 as arising from a narrow rotating starburst ring of radius 22 pc enclosing a mass of 7 x 10^6 Msun. We show how both the compact and apparently diffuse maser emission from this ring can arise from a single phase of unsaturated maser clouds amplifying background radio continuum. The masing clouds are estimated to have a diameter of <0.7 pc and internal velocity dispersion of about 20 km/s. We find that the clouds are neither self-gravitating nor pressure confined but are freely expanding. Their dispersal lifetimes may set the vertical thickness of the ring. For an estimated internal density of 3 x 10^3 cm^-3, cloud masses are of order 24 Msun. The observed spectral features and velocity gradients indicate that the clouds must be outflowing and escaping the nucleus. The cloud mass outflow rate is estimated to be 0.8 Msun/yr, while the star formation rate is about 19 Msun/yr. Associated ionised gas, possibly generated from dissipated...

  8. Young star clusters: Clues to galaxy formation and evolution

    Anders, P.; Alvensleben, U. Fritze--v.; de Grijs, R.

    2003-01-01

    Young clusters are observed to form in a variety of interacting galaxies and violent starbursts, a substantial number resembling the progenitors of the well-studied globular clusters in mass and size. By studying young clusters in merger remnants and peculiar galaxies, we can therefore learn about the violent star formation history of these galaxies. We present a new set of evolutionary synthesis models of our GALEV code specifically developed to include the gaseous emission of presently form...

  9. ASTRO-H White Paper - High Resolution Spectroscopy of Interstellar and Circumgalactic Gas in the Milky Way and Other Galaxies

    Paerels, F; Anabuki, N; Costantini, E; de Vries, C; Fujimoto, R; Hornschemeier, A; Iizuka, R; Kilbourne, C; Konami, S; LaMassa, S; Loewenstein, M; McCammon, D; Matsushita, K; McNamara, B; Mitsuishi, I; Nagino, R; Nakagawa, T; Porter, S; Sakai, K; Smith, R K; Takei, Y; Tsuru, T; Uchiyama, H; Yamaguchi, H; Yamauchi, S

    2014-01-01

    We describe the potential of high resolution imaging spectroscopy with the SXS on ASTRO-H to advance our understanding of the interstellar- and circumgalactic media of our own Galaxy, and other galaxies. Topics to be addressed range from absorption spectroscopy of dust in the Galactic interstellar medium, to observations to constrain the total mass-, metal-, and energy flow out of starburst galaxies.

  10. Physics of Coevolution of Galaxies and Supermassive Black Holes

    Cen, Renyue

    2011-01-01

    A model for coevolution of galaxies and supermassive black holes (SMBH) is presented that is physically based. The starting point is a gas-rich major merger that triggers a starburst and the endpoint is a quiescent elliptical galaxy many gigayears later. There is an approximate coevolution between starburst galaxies and elliptical galaxies, although it is not exact in several important ways. Starburst precedes the onset of main SMBH growth with a gap of time equal to ~100Myr and is responsible for shutting down its own activities; AGN has little to do with it. While starburst occurs earlier and lasts for only about 100Myrs, the AGN accretion occurs later and lasts for ~1 Gyr or longer with a diminishing Eddington ratio. The main AGN growth in post-starburst phase is fueled by recycled gas from inner bulge stars and self-regulated. The predicted relation between SMBH mass and bulge mass/velocity dispersion is consistent with observations. A suite of testable and falsifiable predictions and implications with re...

  11. NGC1266: Compton-thick AGN or Ultra-compact Starburst?

    Lanz, Lauranne; Alatalo, Katherine A.; Brightman, Murray; Ogle, Patrick M.; Appleton, Philip N.

    2016-01-01

    NGC1266 is a nearby lenticular galaxy hosting a massive molecular outflow driven by its active galactic nucleus (AGN). The turbulence injected into its ISM by the outflow may account for the suppression of its star formation by a factor of 50-150. ALMA and CARMA measurements of dense gas tracers had shown that its nuclear region lies behind a column of N(H2) = 3 x 10^24 cm^-2, and ALMA barely resolved a region of continuum FIR emission contained within 30pc of the nucleus emitting L(IR)>10^10 solar luminosities. With out recent NuSTAR observation of this galaxies, we determine whether the dust is heated by a Compton-thick AGN or an ultra-compact central starburst.

  12. THE ANATOMY OF AN EXTREME STARBURST WITHIN 1.3 Gyr OF THE BIG BANG REVEALED BY ALMA

    We present further analysis of the [C II] 158 μm fine structure line and thermal dust continuum emission from the archetype extreme starburst/active galactic nucleus (AGN) group of galaxies in the early universe, BRI 1202–0725 at z = 4.7, using the Atacama Large Millimeter Array. The group has long been noted for having a closely separated (26 kpc in projection) FIR-hyperluminous quasar host galaxy and an optically obscured submillimeter galaxy (SMG). A short ALMA test observation reveals a rich laboratory for the study of the myriad processes involved in clustered massive galaxy formation in the early universe. Strong [C II] emission from the SMG and the quasar have been reported earlier by Wagg et al. based on these observations. In this paper, we examine in more detail the imaging results from the ALMA observations, including velocity channel images, position-velocity plots, and line moment images. We present detections of [C II] emission from two Lyα-selected galaxies in the group, demonstrating the relative ease with which ALMA can detect the [C II] emission from lower star formation rate galaxies at high redshift. Imaging of the [C II] emission shows a clear velocity gradient across the SMG, possibly indicating rotation or a more complex dynamical system on a scale ∼10 kpc. There is evidence in the quasar spectrum and images for a possible outflow toward the southwest, as well as more extended emission (a bridge), between the quasar and the SMG, although the latter could simply be emission from Lyα-1 blending with that of the quasar at the limited spatial resolution of the current observations. These results provide an unprecedented view of a major merger of gas-rich galaxies driving extreme starbursts and AGN accretion during the formation of massive galaxies and supermassive black holes within 1.3 Gyr of the big bang.

  13. Spatially Resolved WFC3/Grism Spectral Line Imaging of Gravitational Lensed Herschel-selected Luminous Dusty Starbursts

    Cooray, Asantha

    2013-10-01

    We propose WFC3 G102 and G141 grism spectral imaging of two gravitationally lensed dusty, starburst galaxies found with the 600 square degree Herschel-ATLAS survey. One galaxy is the brightest {both in far-IR at 250 micron and in near-IR in J/K-band}, while the second is the largest {11 arcsec on the sky} of the lensed sub-mm galaxies in a sample of 200 imaged with WFC3/F110W. The two galaxies are at redshifts that are optimal for grism observations with HST/WFC3. The lensing flux magnification and spatial enhancement makes them very unique for the study proposed hereand will increase the number of lensed galaxies imaged in spectral lines with WFC3 grisms to three from existing single serendipitous lens studied in HST-3D survey. With WFC3 grism spectra taken in a specific orientation to minimize foreground and lensing galaxy confusion we can map each of these galaxies in a variety of spatially-resolved spectral lines in the rest-frame optical, including impostant Balmer lines for studies on the interstellar medium. The grism spectra will allow us to determine the gas-phase metallicities of these two galaxies and to study the extinction of optically-thin regions compared to direct sub-mm emission seen in interferometric continuum images of optically thick dust in starbursting knots and clumps. With spatial resolution provided by gravitational lensing combined with HST/WFC3 resolution, we will be able to study the dependence of line ratios in high density/SFR regions to low dense diffuse environments.

  14. A panchromatic survey of post-starburst mergers: searching for feedback

    De Propris, Roberto; Melnick, Jorge

    2014-04-01

    We consider the morphology, stellar populations, structure and AGN activity of 10 post-starburst (K+A) galaxies with Hubble Space Telescope (HST) observations, full spectral coverage in the optical, spectral energy distributions from 0.2 to 160 μm, X-ray and radio data. Our results show that the post-starburst galaxy (PSG) phenomenon is related to mergers and interactions, and that star formation was likely triggered during close passes prior to final coalescence. We performed a detailed qualitative analysis of the observed light distribution, including low surface brightness tidal features and colour profiles, in high-resolution multiband imaging with HST. We find evidence that star formation was centrally concentrated and that quenching took place from the inside-out, consistent with the occurrence of a feedback episode. Most of our PSGs contain massive bulges and therefore should host supermassive black holes. We search for AGN activity in spectra (line ratios), optical variability, X-ray emission at 0.5-7.0 KeV and radio emission at 20 cm: all four lines of evidence show that there is no active AGN accreting at more than 0.1 per cent of the Eddington luminosity. We conclude that mergers may be a necessary, but not a sufficient condition, for AGN activity and that they are not likely to be important in our objects. If PSGs are good test cases for quenching and evolution to the red sequence, AGNs may play a smaller role than expected.

  15. Central regions of LIRGs: rings, hidden starbursts, Supernovae and star clusters

    Vaisanen, Petri; Kankare, Erkki; Kotilainen, Jari; Mattila, Seppo; Rajpaul, Vinesh; Randriamanakoto, Zara; Reunanen, Juha; Ryder, Stuart; Zijlstra, Albert

    2012-01-01

    We study star formation (SF) in very active environments, in luminous IR galaxies, which are often interacting. A variety of phenomena are detected, such as central starbursts, circumnuclear SF, obscured SNe tracing the history of recent SF, massive super star clusters, and sites of strong off-nuclear SF. All of these can be ultimately used to define the sequence of triggering and propagation of star-formation and interplay with nuclear activity in the lives of gas rich galaxy interactions and mergers. In this paper we present analysis of high-spatial resolution integral field spectroscopy of central regions of two interacting LIRGs. We detect a nuclear 3.3 um PAH ring around the core of NGC 1614 with thermal-IR IFU observations. The ring's characteristics and relation to the strong star-forming ring detected in recombination lines are presented, as well as a scenario of an outward expanding starburst likely initiated with a (minor) companion detected within a tidal feature. We then present NIR IFU observatio...

  16. The Properties of Post-Starburst Quasars Based on Optical Spectroscopy

    Cales, Sabrina L; Shang, Zhaohui; Runnoe, Jessie C; DiPompeo, Michael A; Bennert, Vardha Nicola; Canalizo, Gabriela; Hiner, Kyle D; Stoll, R; Ganguly, Rajib; Diamond-Stanic, Aleksandar

    2012-01-01

    We present optical spectroscopy of a sample of 38 post-starburst quasars (PSQs) at z ~ 0.3, 29 of which have morphological classifications based on Hubble Space Telescope imaging. These broad-lined active galactic nuclei (AGNs) possess the spectral signatures of massive intermediate-aged stellar populations making them potentially useful for studying connections between nuclear activity and host galaxy evolution. We model the spectra in order to determine the ages and masses of the host stellar populations, and the black hole masses and Eddington fractions of the AGNs. Our model components include an instantaneous starburst, a power-law, and emission lines. We find the PSQs have MBH ~ 10^8 Msun accreting at a few percent of Eddington luminosity and host ~ 10^10.5 Msun stellar populations which are several hundred Myr to a few Gyr old. We investigate relationships among these derived properties, spectral properties, and morphologies. We find that PSQs hosted in spiral galaxies have significantly weaker AGN lum...

  17. Far-infrared spectroscopy of a lensed starburst: a blind redshift from Herschel

    George, R D; Hopwood, R; Riechers, D A; Bussmann, R S; Cox, P; Dye, S; Krips, M; Negrello, M; Neri, R; Serjeant, S; Valtchanov, I; Baes, M; Bourne, N; Clements, D L; De Zotti, G; Dunne, L; Eales, S A; Ibar, E; Maddox, S; Smith, M W L; Valiante, E; van der Werf, P

    2013-01-01

    We report the redshift of HATLAS J132427.0+284452 (hereafter HATLAS J132427), a gravitationally lensed starburst galaxy, the first determined 'blind' by the Herschel Space Observatory. This is achieved via the detection of [C II] consistent with z = 1.68 in a far-infrared spectrum taken with the SPIRE Fourier Transform Spectrometer. We demonstrate that the [C II] redshift is secure via detections of CO J = 2 - 1 and 3 - 2 using the Combined Array for Research in Millimeter-wave Astronomy and the Institut de Radioastronomie Millimetrique's Plateau de Bure Interferometer. The intrinsic properties appear typical of high-redshift starbursts despite the high lensing-amplified fluxes, proving the ability of the FTS to probe this population with the aid of lensing. The blind detection of [C II] demonstrates the potential of the SAFARI imaging spectrometer, proposed for the much more sensitive SPICA mission, to determine redshifts of multiple dusty galaxies simultaneously without the benefit of lensing.

  18. How does star formation proceed in the circumnuclear starburst ring of NGC 6951?

    van der Laan, T P R; Emsellem, E; Hunt, L K; McDermid, R M; Liu, G

    2013-01-01

    Gas inflowing along stellar bars is often stalled at the location of circumnuclear rings, that form an effective reservoir for massive star formation and thus shape the central regions of galaxies. However, how exactly star formation is proceeding within these circumnuclear starburst rings is subject of debate. Two main scenarios for this process have been put forward: In the first the onset of star formation is regulated by the total amount of gas present in the ring with star forming starting once a mass threshold has reached in a `random' position within the ring like `popcorn'. In the second star formation preferentially takes place near the locations where the gas enters the ring. This scenario has been dubbed `pearls-on-a-string'. Here we combine new optical IFU data covering the full stellar bar with existing multi-wavelength data to study in detail the 580 pc radius circumnuclear starburst ring in the nearby spiral galaxy NGC 6951. Using HST archival data together with Sauron and Oasis IFU data, we de...

  19. Angular correlation between IceCube high-energy starting events and starburst sources

    Moharana, Reetanjali

    2016-01-01

    Starburst galaxies and star-forming regions in the Milkyway, with high rate of supernova activities, are candidate sources of high-energy neutrinos. Using a gamma-ray selected sample of these sources we perform statistical analysis of their angular correlation with the four-year sample of high-energy starting events (HESE), detected by the IceCube Neutrino Observatory. We find that the two samples (starburst galaxies and local star-forming regions) are correlated with cosmic neutrinos at $\\sim (2-3)\\sigma$ (pre-trial) significance level, when the full HESE sample with deposited energy $\\gtrsim 20$~TeV is considered. However when we consider the HESE sample with deposited energy $\\gtrsim 60$~TeV, which is almost free of atmospheric neutrino and muon backgrounds, the significance of correlation decreased drastically. We perform a similar study for Galactic sources in the 2FHL catalog as well, obtaining $\\sim (2-3)\\sigma$ (pre-trial) correlation, however the significance of correlation increases with higher cuto...

  20. Far-infrared spectroscopy of a lensed starburst: a blind redshift from Herschel

    George, R. D.; Ivison, R. J.; Hopwood, R.; Riechers, D. A.; Bussmann, R. S.; Cox, P.; Dye, S.; Krips, M.; Negrello, M.; Neri, R.; Serjeant, S.; Valtchanov, I.; Baes, M.; Bourne, N.; Clements, D. L.; De Zotti, G.; Dunne, L.; Eales, S. A.; Ibar, E.; Maddox, S.; Smith, M. W. L.; Valiante, E.; van der Werf, P.

    2013-11-01

    We report the redshift of HATLAS J132427.0+284452 (hereafter HATLAS J132427), a gravitationally lensed starburst galaxy, the first determined `blind' by the Herschel Space Observatory. This is achieved via the detection of [C II] consistent with z = 1.68 in a far-infrared spectrum taken with the SPIRE Fourier Transform Spectrometer (FTS). We demonstrate that the [C II] redshift is secure via detections of CO J = 2 → 1 and 3 → 2 using the Combined Array for Research in Millimeter-wave Astronomy and the Institut de Radioastronomie Millimétrique's Plateau de Bure Interferometer. The intrinsic properties appear typical of high-redshift starbursts despite the high lensing-amplified fluxes, proving the ability of the FTS to probe this population with the aid of lensing. The blind detection of [C II] demonstrates the potential of the SPICA Far-infrared Instrument imaging spectrometer, proposed for the much more sensitive Space Infrared Telescope for Cosmology and Astrophysics mission, to determine redshifts of multiple dusty galaxies simultaneously without the benefit of lensing.

  1. Observations of the Hubble Deep Field with the Infrared Space Observatory .5. Spectral energy distributions, starburst models and star formation history

    Rowan Robinson, M.; Mann, R.G.; Oliver, S.J.;

    1997-01-01

    star formation rate can be deduced from the far-infrared luminosity, and derive star formation rates for these galaxies of 8-1000 phi M. yr(-1), where phi takes account of the uncertainty in the initial mass function, The HDF galaxies detected by ISO are clearly forming stars at, a prodigious rate...... compared with nearby normal galaxies, We discuss the implications of our detections for the history of star and heavy element formation in the Universe, Although uncertainties in the calibration, reliability of source detection, associations and starburst models remain, it is clear that dust plays an...... important role in star formation out to redshift 1 at least....

  2. Recent Star-formation in Post-Starburst Quasars

    Townsend, Shonda; Ganguly, R.; Strom, A.; Cales, S.; Brotherton, M. S.

    2011-01-01

    Post-Starburst Quasars (PSQ, alternatively Q+As) show simultaneously the spectrum of a massive A-type stellar population and a quasar. The prototype PSQ, UNJ1025-0040, shows a UV excess over the quasar spectrum, indicating more recent star-formation (Brotherton et al 2002). To gauge the frequency and distribution of these younger stellar populations in PSQs, we have collected GALEX (GR45) and 2MASS photometry for 409 objects. The objects are catalog 609 spectroscopically-selected PSQs from Brotherton et al. (2010) that uses similar criteria as Zabludoff et al. (1996) for post-starburst galaxies (PSG, E+A). For comparison, we have compiled two samples: (1) 16,000 quasars that is matched in redshift (0.01-0.7) and Sloan-u magnitude (16.1-21.2), which is blueward of the Balmer edge and provides the least contamination from the massive stellar population; and (2) 500 PSGs from Goto et al. (2007). 389 (55) PSQs show an NUV (FUV) excess over the expected UV flux if the underlying quasar were ``normal.'’ 126 (460) objects show an NUV (FUV) decrement. The observed NUV to u-band flux ratio of the median PSQ rises from 1 at z=0.01 to 2.5 at z=0.4, while the same for the median QSO remains at 1. The observed FUV to u-band flux ratio of the median QSO rises slightly from 0.6 to 0.8 over the redshift range 0.05-0.2, whereas the median PSQ is nearly a factor of three lower. The disparity between the median PSQ and QSO suggests the presence of young stars that add in NUV light, but not FUV light. To quantify the youth and mass of this putative population, we will present preliminary efforts to model PSQs using two simple stellar populations, an underlying quasar, and dust reddening. We acknowledge funding from GALEX through grant NNX10AC63G.

  3. Connecting galaxy and supermassive black hole growth during the last 8 billion years

    Juneau, Stephanie

    It has become increasingly clear that a complete picture of galaxy evolution requires a better understanding of the role of Active Galactic Nuclei (AGN). In particular, they could be responsible for regulating star formation and galaxy growth via feedback processes. There are also competing views about the main modes of stellar growth and supermassive black hole growth in galaxies that need to be resolved. With high infrared luminosities (thus star formation rates) and a frequent occurrence of AGN, galaxies selected in the far-infrared wavebands form an ideal sample to search for a connection between AGN and star formation. The first part of this thesis contains a detailed analysis of the molecular gas properties of nearby infrared luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs). We find that the enhanced molecular gas density in the most IR-luminous systems can be explained by major galaxy mergers, and that AGN are more likely to reside in higher-density systems. While the frequent concurrence of AGN and galaxy mergers in ULIRGs was already established, this work provides a coherent framework that explains trends observed with five molecular gas tracers with a broad range of critical densities, and a comparison with simulations that reproduce observed molecular line ratios without invoking AGN-induced chemistry. The second part of the thesis presents an analysis of the AGN content of intermediate redshift galaxies (0.3 < z < 1). However, identifying complete AGN samples at these redshift is challenging because it is difficult to find X-ray weak or absorbed AGN. To alleviate this problem, we developed the Mass-Excitation (MEx) diagram, which is applicable out to redshift of ˜ 1 with existing optical spectra. It improves the overall AGN census by detecting AGN that are missed in even the most sensitive X-ray surveys. The new diagnostic was used to study the concurrence of star formation and AGN in 70 micron-selected galaxies from the Far

  4. Imaging and Spectroscopy of Arp 104: A Post-starburst Interacting Pair with Cross-Fuelling?

    Roche, N

    2006-01-01

    We perform UBR imaging and optical spectroscopy of the interacting galaxy pair Arp 104, at z=0.0098. This consists of NGC5218, a disturbed Sb barred spiral with an inclined outer shell, the round spheroidal NGC5216, a connecting bridge of length 50 kpc and a curved plume. Neither galaxy shows emission lines. NGC5218 has strong Balmer lines and appears to have undergone a major starburst some 0.2 Gyr ago, triggered by the last close passage of the two galaxies. The galaxy is very red in its centre, suggesting it is dusty, but its outer regions, and the bridge connecting the two galaxies, have the blue colours of 0.2-0.4 Gyr old stars. NGC5216 lacks strong Balmer lines but outside its centre is blue in U-B, suggesting it experienced a star-formation episode only about 40 Myr ago. This could have been fuelled by gas from NGC5218, transfered through the bridge. The bridge passes through NGC5216 to emerge as a plume extending 14 kpc to the SW. The plume, from its colours, is very young and may be a site of ongoing...

  5. The energy source and dynamics of infrared luminous galaxy ESO 148-IG002

    Leslie, Sarah; Rich, Jeffrey; Kewley, Lisa; Dopita, Michael

    2014-01-01

    ESO 148-IG002 represents a transformative stage of galaxy evolution, containing two galaxies at close separation which are currently coalescing into a single galaxy. We present integral field data of this galaxy from the ANU Wide Field Spectrograph (WiFeS). We analyse our integral field data using optical line ratio maps and velocity maps. We apply active galactic nucleus (AGN), star-burst and shock models to investigate the relative contribution from star-formation, shock excitation and AGN ...

  6. Comparing the Evolution of the Galaxy Disk Sizes with CDM Models The Hubble Deep Field

    Giallongo, E; Poli, F; D'Odorico, S; Fontana, A

    2000-01-01

    The intrinsic sizes of the field galaxies with I-19) galaxies is skewed with respect to the CDM predictions and an excess of small-size disks (R_d<2 kpc) is already present at z~ 0.5. The excess persists up to z~3 and involves brighter galaxies . Such an excess may be reduced if luminosity-dependent effects, like starburst activity in interacting galaxies, are included in the physical mechanisms governing the star formation history in CDM models.

  7. SGAS 143845.1+145407: A BIG, COOL STARBURST AT REDSHIFT 0.816

    We present the discovery and detailed multi-wavelength study of a strongly lensed luminous infrared galaxy at z = 0.816. Unlike most known lensed galaxies discovered at optical or near-infrared wavelengths, this lensed source is red, (r – Ks ) AB = 3.9, which the data presented here demonstrate is due to ongoing dusty star formation. The overall lensing magnification (a factor of 17) facilitates observations from the blue optical through to 500 μm, fully capturing both the stellar photospheric emission and the re-processed thermal dust emission. We also present optical and near-IR spectroscopy. These extensive data show that this lensed galaxy is in many ways typical of IR-detected sources at z ∼ 1, with both a total luminosity and size in accordance with other (albeit much less detailed) measurements for samples of galaxies observed in deep fields with the Spitzer telescope. Its far-infrared spectral energy distribution is well fit by local templates that are an order of magnitude less luminous than the lensed galaxy; local templates of comparable luminosity are too hot to fit. Its size (D ∼ 7 kpc) is much larger than local luminous infrared galaxies, but in line with sizes observed for such galaxies at z ∼ 1. The star formation appears uniform across this spatial scale. In this source, the luminosity of which is typical of sources that dominate the cosmic infrared background, we find that star formation is spatially extended and well organized, quite unlike the compact merger-driven starbursts that are typical for sources of this luminosity at z ∼ 0.

  8. Neutral Atomic Carbon in Centers of Galaxies

    Israel, F.P.; Baas, F

    2001-01-01

    We present measurements of the emission from the centers of fifteen spiral galaxies in the 3P1-3P0 [CI] fine-structure transition at 492 GHz. Observed galaxy centers range from quiescent to starburst to active. The intensities of neutral carbon, the J=2-1 transition of 13CO and the J=4-3 transition of 12CO are compared in matched beams. Most galaxy centers emit more strongly in [CI] than in 13CO, completely unlike the situation pertaining to Galactic molecular cloud regions. [CI] intensities ...

  9. Tracing star formation in galaxies with molecular line and continuum observations

    Kohno, K; Hatsukade, B; Tanaka, K; Iono, D; Nakanishi, K; Tosaki, T; Sawada, T; Kawabe, R; Ezawa, H; Yamaguchi, N; Tamura, Y; Wilson, G; Yun, M S; Hughes, D; Matsushita, S; Hsieh, P -Y

    2008-01-01

    We report our recent progress on extragalactic spectroscopic and continuum observations, including HCN(J=1-0), HCO$^+$(J=1-0), and CN(N=1-0) imaging surveys of local Seyfert and starburst galaxies using the Nobeyama Millimeter Array, high-J CO observations (J=3-2 observations using the Atacama Submillimeter Telescope Experiment (ASTE) and J=2-1 observations with the Submillimeter Array) of galaxies, and $\\lambda$ 1.1 mm continuum observations of high-z violent starburst galaxies using the bolometer camera AzTEC mounted on ASTE.

  10. Spectral Decomposition of Broad-Line AGNs and Host Galaxies

    Vanden Berk, Daniel E; Yip, C W; Schneider, D P; Connolly, A J; Burton, R E; Jester, S; Hall, P B; Szalay, A S; Brinkmann, J; Berk, Daniel E. Vanden; Shen, Jiajian; Yip, Ching-Wa; Schneider, Donald P.; Connolly, Andrew J.; Burton, Ross E.; Jester, Sebastian; Hall, Patrick B.; Szalay, Alex S.; Brinkmann, John

    2005-01-01

    Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification. We show how the accuracy of the decomposition depends upon S/N, host galaxy fraction, and the galaxy class. Based on the eigencoefficients, the sample of SDSS broad-line AGN host galaxies spans a wide range of spectral types, but the distribution differs significantly from inactive galaxies. In particular, post-starburst activity appears to be much more common among AGN host galaxies. The luminosities of the hosts are much higher than expected for normal early-type galaxies, and their colors become increasing...

  11. The Dust Content and Opacity of Actively Star-Forming Galaxies

    Calzetti, D.; Armus, L.; Bohlin, R. C.; Kinney, A. L.; Koornneef, J.; Storchi-Bergmann, T.

    1999-01-01

    Submitted to: Astrophys. J. Abstract: (Abridged) We present far-infrared (FIR) photometry at 150 micron and 205 micron of eight low-redshift starburst galaxies obtained with the ISO Photometer. Five of the eight galaxies are detected in both wavebands and these data are used, in conjunction with IRA

  12. Central regions of LIRGs: rings, hidden starbursts, Supernovae and star clusters

    Väisänen, Petri; Escala, Andres; Kankare, Erkki; Kotilainen, Jari; Mattila, Seppo; Rajpaul, Vinesh; Randriamanakoto, Zara; Reunanen, Juha; Ryder, Stuart; Zijlstra, Albert

    2012-07-01

    We study star formation (SF) in very active environments, in luminous IR galaxies, which are often interacting. A variety of phenomena are detected, such as central starbursts, circumnuclear SF, obscured SNe tracing the history of recent SF, massive super star clusters, and sites of strong off-nuclear SF. All of these can be ultimately used to define the sequence of triggering and propagation of star-formation and interplay with nuclear activity in the lives of gas rich galaxy interactions and mergers. In this paper we present analysis of high-spatial resolution integral field spectroscopy of central regions of two interacting LIRGs. We detect a nuclear 3.3 μm PAH ring around the core of NGC 1614 with thermal-IR IFU observations. The ring's characteristics and relation to the strong star-forming ring detected in recombination lines are presented, as well as a scenario of an outward expanding starburst likely initiated with a (minor) companion detected within a tidal feature. We then present NIR IFU observations of IRAS 19115-2124, aka the Bird, which is an intriguing triple encounter. The third component is a minor one, but, nevertheless, is the source of 3/4 of the SFR of the whole system. Gas inflows and outflows are detected in their nuclei locations. Finally, we briefly report on our on-going NIR adaptive optics imaging survey of several dozen LIRGs. We have detected highly obscured core-collapse SNe in the central kpc, and discuss the statistics of "missing SNe" due to dust extinction. We are also determining the characteristics of hundreds of super star clusters in and around the core regions of LIRGs, as a function of host-galaxy properties.

  13. Feedback from starbursts: 30 Dorado as a case study

    Wang, Q. Daniel; lim, Seunghwan

    2016-01-01

    Stellar feedback remains a key uncertain aspect in galaxy formation and evolution theories. In addition to the mechanical energy injection from fast stellar winds and supernovae of massive stars, their radiative transfer feedback (via direct and indirect/dust-processed radiation pressures and photo-ionization) has also been proposed to play a significant role in dispersing dense dusty gas and possibly in driving outflows from starburst regions. To test the relative efficiency of these two forms of the stellar feedback, we study the energetics of the Tarantula Nebula (30 Doradus) in the Large Magellanic Cloud. The nebula consists of various blisters of diffuse hot plasma enveloped by cool gas. Based on the X-ray spectroscopy of the nebula, using a 100 ks Suzaku X-ray observation, we estimate the thermal energy of the enclosed plasma, accounting for its temperature distribution and foreground absorption variation. The estimated thermal energy is far short of the expected fraction of the mechanical energy input from the central young stellar association (NGC 2070) of the nebula, according to the classic superbubble solution, indicating a substantial loss of energy via probably hot electron-dust interaction and cosmic-ray acceleration, as well as the cool shell formation. We further characterize the kinetic energy of dense dusty gas, using a recently published dust mass map and the velocity dispersion inferred from molecular and HI gases in the nebula. However, this component of the kinetic energy appears to be dominated by the turbulent and bulk motions of HII gas. The total kinetic energy of the nebula is consistent with the expected fraction of the mechanical energy input. Therefore, the radiation transfer feedback does not seem to play a significant role in the expansion of 30 Doradus.

  14. Calibrating UV Star Formation Rates for Dwarf Galaxies from STARBIRDS

    McQuinn, Kristen B W; Dolphin, Andrew E; Mitchell, Noah P

    2015-01-01

    Integrating our knowledge of star formation traced by observations at different wavelengths is essential for correctly interpreting and comparing star formation activity in a variety of systems and environments. This study compares extinction corrected integrated ultraviolet (UV) emission from resolved galaxies with color-magnitude diagram (CMD) based star formation rates (SFRs) derived from resolved stellar populations and CMD fitting techniques in 19 nearby starburst and post-starburst dwarf galaxies. The datasets are from the panchromatic STARBurst IRregular Dwarf Survey (STARBIRDS) and include deep legacy GALEX UV imaging, HST optical imaging, and Spitzer MIPS imaging. For the majority of the sample, the integrated near UV fluxes predicted from the CMD-based SFRs - using four different models - agree with the measured, extinction corrected, integrated near UV fluxes from GALEX images, but the far UV predicted fluxes do not. Further, we find a systematic deviation between the SFRs based on integrated far U...

  15. HIERARCHICAL STAR FORMATION IN NEARBY LEGUS GALAXIES

    Hierarchical structure in ultraviolet images of 12 late-type LEGUS galaxies is studied by determining the numbers and fluxes of nested regions as a function of size from ∼1 to ∼200 pc, and the number as a function of flux. Two starburst dwarfs, NGC 1705 and NGC 5253, have steeper number-size and flux-size distributions than the others, indicating high fractions of the projected areas filled with star formation. Nine subregions in seven galaxies have similarly steep number-size slopes, even when the whole galaxies have shallower slopes. The results suggest that hierarchically structured star-forming regions several hundred parsecs or larger represent common unit structures. Small galaxies dominated by only a few of these units tend to be starbursts. The self-similarity of young stellar structures down to parsec scales suggests that star clusters form in the densest parts of a turbulent medium that also forms loose stellar groupings on larger scales. The presence of super star clusters in two of our starburst dwarfs would follow from the observed structure if cloud and stellar subregions more readily coalesce when self-gravity in the unit cell contributes more to the total gravitational potential

  16. Galaxy Formation and Evolution

    Nagamine, Kentaro; Reddy, Naveen; Daddi, Emanuele; Sargent, Mark T.

    2016-07-01

    In this chapter, we discuss the current status of observational and computational studies on galaxy formation and evolution. In particular, a joint analysis of star-formation rates (SFRs), stellar masses, and metallicities of galaxies throughout cosmic time can shed light on the processes by which galaxies build up their stellar mass and enrich the environment with heavy elements. Comparison of such observations and the results of numerical simulations can give us insights on the physical importance of various feedback effects by supernovae and active galactic nuclei. In Sect. 1, we first discuss the primary methods used to deduce the SFRs, stellar masses, and (primarily) gas-phase metallicities in high-redshift galaxies. Then, we show how these quantities are related to each other and evolve with time. In Sect. 2, we further examine the distribution of SFRs in galaxies following the `Main Sequence' paradigm. We show how the so-called `starbursts' display higher specific SFRs and SF efficiencies by an order of magnitude. We use this to devise a simple description of the evolution of the star-forming galaxy population since z ˜3 that can successfully reproduce some of the observed statistics in the infrared (IR) wavelength. We also discuss the properties of molecular gas. In Sect. 3, we highlight some of the recent studies of high-redshift galaxy formation using cosmological hydrodynamic simulations. We discuss the physical properties of simulated galaxies such as luminosity function and escape fraction of ionizing photons, which are important statistics for reionization of the Universe. In particular the escape fraction of ionizing photons has large uncertainties, and studying gamma-ray bursts (which is the main topic of this conference) can also set observational constraints on this uncertain physical parameter as well as cosmic star formation rate density.

  17. MAXIMALLY STAR-FORMING GALACTIC DISKS. I. STARBURST REGULATION VIA FEEDBACK-DRIVEN TURBULENCE

    Star formation rates in the centers of disk galaxies often vastly exceed those at larger radii, whether measured by the surface density of star formation ΣSFR, by the star formation rate per unit gas mass, ΣSFR/Σ, or even by total output. In this paper, we investigate the idea that central starbursts are self-regulated systems in which the momentum flux injected to the interstellar medium (ISM) by star formation balances the gravitational force confining the ISM gas in the disk. For most starbursts, supernovae are the largest contributor to the momentum flux, and turbulence provides the main pressure support for the predominantly molecular ISM. If the momentum feedback per stellar mass formed is p*/m* ∼ 3000 km s-1, the predicted star formation rate is ΣSFR ∼ 2πGΣ2 m*/p* ∼ 0.1 Msun kpc-2 yr-1(Σ/100 Msun pc-2)2 in regions where gas dominates the vertical gravity. We compare this prediction with numerical simulations of vertically resolved disks that model star formation including feedback, finding good agreement for gas surface densities in the range Σ ∼ 102-103 Msun pc-2. We also compare to a compilation of star formation rates and gas contents from local and high-redshift galaxies (both mergers and normal galaxies), finding good agreement provided that the conversion factor XCO from integrated CO emission to H2 surface density decreases modestly as Σ and ΣSFR increase. Star formation rates in dense, turbulent gas are also expected to depend on the gravitational free-fall time at the corresponding mean ISM density ρ0; if the star formation efficiency per free-fall time is εff(ρ0) ∼ 0.01, the turbulent velocity dispersion driven by feedback is expected to be vz = 0.4 εff(ρ0)p*/m* ∼ 10 km s-1, relatively independent of Σ or ΣSFR. Turbulence-regulated starbursts (controlled by kinetic momentum feedback) are part of the larger scheme of self-regulation; primarily atomic low-Σ outer disks may have star formation regulated by ultraviolet

  18. AGN-starburst evolutionary connection : a physical interpretation based on radiative feedback

    Ishibashi, W.; Fabian, A. C.

    2016-08-01

    Observations point towards a close connection between nuclear starbursts, active galactic nuclei (AGN), and outflow phenomena. An evolutionary sequence, starting from a dust-obscured ultra-luminous infrared galaxy and eventually leading to an unobscured optical quasar, has been proposed and discussed in the literature. AGN feedback is usually invoked to expel the obscuring gas and dust in a blow-out event, but the underlying physical mechanism remains unclear. We consider AGN feedback driven by radiation pressure on dust, which directly acts on the obscuring dusty gas. We obtain that radiative feedback can potentially disrupt dense gas in the infrared-optically thick regime, and that an increase in the dust-to-gas fraction leads to an increase in the effective Eddington ratio. Thus the more dusty gas is preferentially expelled by radiative feedback, and the central AGN is prone to efficiently remove its own obscuring dust cocoon. Large amounts of dust imply heavy obscuration but also powerful feedback, suggesting a causal link between dust obscuration and blow-out. In this picture, AGN feedback and starburst phenomena are intrinsically coupled through the production of dust in supernova explosions, leading to a natural interpretation of the observed evolutionary path.

  19. M82, Starbursts, Star Clusters, and the Formation of Globular Clusters

    Keto, E; Lo, K Y; Keto, Eric; Ho, Luis C.

    2005-01-01

    We observed the nearby starburst galaxy M82 in CO in the higher frequency (2--1) transition to achieve an angular resolution below 1 arc second or 17 pc at the target. We resolved the molecular gas into a large number of compact clouds, with masses ranging from about 2x10^3 to 2x10^6 solar masses. The mass spectrum scales as N(M) ~ M^-1.5, similar to the mass spectra of young massive star clusters suggesting that individual molecular clouds are transformed in the starburst into individual star clusters. The larger clouds are surrounded by supernovae and HII regions suggesting that star formation proceeds from the outside of the clouds and progresses inward consistent with triggering by a sudden increase in external pressure. The clouds with internal star formation have velocity gradients and inverse P-Cygni spectral line profiles indicating inward motions of 35 kms consistent with shock driven compression. Diffuse free-free radio emission and X-ray emission around the clouds provides evidence for superheated ...

  20. Cosmic Rays, Gamma-Rays, & Neutrinos in the Starburst Nuclei of Arp 220

    Yoast-Hull, Tova M; Zweibel, Ellen G

    2015-01-01

    The cores of Arp 220, the closest ultra-luminous infrared starburst galaxy, provide an opportunity to study interactions of cosmic rays under extreme conditions. In this paper, we model the populations of cosmic rays produced by supernovae in the central molecular zones of both starburst nuclei. We find that ~65 - 100% of cosmic rays are absorbed in these regions due to their huge molecular gas contents, and thus, the nuclei of Arp 220 nearly complete proton calorimeters. As the cosmic ray protons collide with the interstellar medium, they produce secondary electrons that are also contained within the system and radiate synchrotron emission. Using results from chi-squared tests between the model and the observed radio spectral energy distribution, we predict the emergent gamma-ray and high-energy neutrino spectra and find the magnetic field to be at milligauss levels. Because of the extremely intense far-infrared radiation fields, the gamma-ray spectrum steepens significantly at TeV energies due to gamma-gamm...

  1. Polycyclic aromatic hydrocarbon (PAH) luminous galaxies at z~1

    Takagi, T; Goto, T; Matsuhara, H; Oyabu, S; Wada, T; Pearson, C P; Lee, H M; Im, M; Lee, M G; Shim, H; Hanami, H; Ishigaki, T; Imai, K; White, G J; Serjeant, S; Malkan, M

    2010-01-01

    Using an AKARI multi-wavelength mid-infrared (IR) survey, we identify luminous starburst galaxies at z> 0.5 based on the PAH luminosity, and investigate the nature of these PAH-selected starbursts. An extragalactic survey with AKARI towards the north ecliptic pole (NEP), the NEP-Deep survey, is unique in terms of a comprehensive wavelength coverage from 2 to 24um using all 9 photometric bands of the InfraRed Camera (IRC). This survey allows us to photometrically identify galaxies whose mid-IR emission is clearly dominated by PAHs. We propose a single colour selection method to identify such galaxies, using two mid-IR flux ratios at 11-to-7um and 15-to-9um (PAH-to-continuum flux ratio in the rest-frame), which are useful to identify starburst galaxies at z~0.5 and 1, respectively. We perform a fitting of the spectral energy distributions (SEDs) from optical to mid-IR wavelengths, using an evolutionary starburst model with a proper treatment of radiative transfer (SBURT), in order to investigate their nature. T...

  2. The Butcher-Oemler effect in a nearby cluster of galaxies?

    The integrated spectra of early-type galaxies in the nearby Abell 262, Pegasus I, and Virgo clusters are compared with those of several field galaxies. The spectra of five galaxies in Pegasus I and one galaxy in the Virgo Cluster show evidence of recent star formation. The average blue magnitude for the star-forming galaxies is M(B) = -20. The star-formation activity in Pegasus I is found to be similar to that of starburst and poststarburst galaxies in Butcher-Oemler clusters at redshifts greater than 2. 38 refs

  3. Luminosity function of the brightest galaxies in the IRAS survey

    Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst galaxies, and more numerous than quasars at the same bolometric luminosity. The far infrared luminosity in the local universe is approximately 25% of the starlight output in the same volume

  4. On the Early Evolution of Young Starbursts

    Rosa-Gonzalez, Daniel; Terlevich, Elena; Terlevich, Roberto

    2009-01-01

    We studied the radio properties of very young massive regions of star formation in HII galaxies, with the aim of detecting episodes of recent star formation in an early phase of evolution where the first supernovae start to appear. The observed radio spectral energy distribution (SED) covers a behaviour range; 1) there are galaxies where the SED is characterized by a synchrotron-type slope, 2) galaxies with a thermal slope, and 3) galaxies with possible free-free absorption at long wavelengths. The latter SED represents a signature of massive star clusters that are still well inside the progenitor molecular cloud. Based on the comparison of the star formation rates (SFR) determined from the recombination lines and those determined from the radio emission we find that SFR(Ha) is on average five times higher than SFR(1.4 GHz). These results suggest that the emission of these galaxies is dominated by a recent and massive star formation event in which the first supernovae (SN) just started to explode. We conclude...

  5. Large family of compact radio sources in the starburst nucleus of NGC 253

    Deep VLA maps of NGC 253 show that it has at least 35 compact radio sources similar to those in the prototypical IR starburst galaxy M82. It is noted that NGC 253 is a twin of M82 in IR spectrum and luminosity as well as distance. Some of the sources in M82 which are rapidly expanding and fading are believed to be extremely young supernova remnants. Most of the sources detected in NGC 253 are unresolved or only marginally resolved, with typical diameters no greater than 2-5 pc. If they are young supernova remnants expanding at 12,000 km/s, the source ages are no more than 160-400 yr. This requires a supernova rate of about 1/0.1 yr. If the compact radio sources are indeed young supernova remnants, star formation must have ceased shortly after the progenitors of the current supernovae were produced. 12 references

  6. SPITZER- AND HERSCHEL-BASED SPECTRAL ENERGY DISTRIBUTIONS OF 24 μm BRIGHT z ∼ 0.3-3.0 STARBURSTS AND OBSCURED QUASARS

    In this paper, we characterize the infrared spectral energy distributions (SEDs) of mid-IR-selected z ∼ 0.3-3.0 and LIR ∼ 1011-1013 L☉ galaxies, and study how their SEDs differ from those of local and high-z analogs. Infrared SEDs depend both on the power source (AGN or star formation) and the dust distribution. Therefore, differences in the SEDs of high-z and local galaxies provide clues as to differences in their physical conditions. Our mid-IR flux-limited sample of 191 sources is unique in size, and spectral coverage, including Spitzer mid-IR spectroscopy. Here, we add Herschel photometry at 250 μm, 350 μm, and 500 μm, which allows us, through fitting an empirical SED model, to obtain accurate total IR luminosities, as well as constrain the relative contributions of AGNs and starbursts to those luminosities. Our sample includes three broad categories of SEDs: ∼23% of the sources are AGNs (i.e., where the AGN contributes >50% of LIR), ∼30% are starbursts where an AGN contributes IR, and the mid-IR spectra are starburst-like (i.e., strong polycyclic aromatic hydrocarbon features); and the largest group (∼47%) are composites which show both significant AGN and starburst activity. The AGN-dominated sources divide into ones that show a strong silicate 9.7 μm absorption feature, implying highly obscured systems, and ones that do not. The high-τ9.7 sources are half of our z > 1.2 AGNs, but show SEDs that are extremely rare among local AGNs. The 30% of the sample that are starbursts, even the z ∼ 2, LIR ∼ 1013 L☉ ones, have lower far-IR to mid-IR continuum ratios than local Ultra Luminous Infrared Galaxies (ULIRGs) or the z ∼ 2 sub-mm galaxies—effectively the SEDs of our z ∼ 2 starburst-dominated ULIRGs are much closer to those of local Luminous Infrared Galaxies than ULIRGs. This is consistent with our earlier finding that, unlike local ULIRGs, our high-z starbursts are typically only in the early stages of a merger. The SEDs of the

  7. Search for Blue Compact Dwarf Galaxies During Quiescence

    Almeida, J Sanchez; Amorin, R; Aguerri, J A; Sanchez-Janssen, R; Tenorio-Tagle, G

    2008-01-01

    Blue Compact Dwarf (BCD) galaxies are metal poor systems going through a major starburst that cannot last for long. We have identified galaxies which may be BCDs during quiescence (QBCD), i.e., before the characteristic starburst sets in or when it has faded away. These QBCD galaxies are assumed to be like the BCD host galaxies. The SDSS/DR6 database provides ~21500 QBCD candidates. We also select from SDSS/DR6 a complete sample of BCD galaxies to serve as reference. The properties of these two galaxy sets have been computed and compared. The QBCD candidates are thirty times more abundant than the BCDs, with their luminosity functions being very similar except for the scaling factor, and the expected luminosity dimming associated with the end of the starburst. QBCDs are redder than BCDs, and they have larger HII region based oxygen abundance. QBCDs also have lower surface brightness. The BCD candidates turn out to be the QBCD candidates with the largest specific star formation rate (actually, with the largest...

  8. Nuclear starburst-driven evolution of the central region in NGC 6764

    Leon, S; Laine, S; Kotilainen, J K; Schinnerer, E; Lee, S -W; Krips, M; Reunanen, J; Scharwächter, J

    2007-01-01

    We study the CO and the radiocontinuum emission in an active galaxy to analyze the interplay between the central activity and the molecular gas. We present new high-resolution observations of the CO(1-0) and CO(2-1) emission lines, and 3.5 cm and 20 cm radio continuum emission in the central region of the LINER/starburst galaxy NGC 6764. The galaxy has an outflow morphology in radio continuum, spatially coincident with the CO and H$\\alpha$ emission, and centered slightly off the radio continuum peak at the LINER nucleus. The total molecular gas mass in the center is about 7x10^8 \\msun, using a CO luminosity to total molecular gas conversion factor that is three times lower than the standard one. CO(1-0) emission is found near the boundaries of the radio continuum emission cone. The outflow has a projected expansion velocity of 25 km/s relative to the systemic velocity of NGC6764. About 4x 10^6 \\msun of molecular gas is detected in the outflow. The approximate location (~1 kpc) of the dynamical inner Lindblad ...

  9. A REDSHIFT SURVEY OF HERSCHEL FAR-INFRARED SELECTED STARBURSTS AND IMPLICATIONS FOR OBSCURED STAR FORMATION

    We present Keck spectroscopic observations and redshifts for a sample of 767 Herschel-SPIRE selected galaxies (HSGs) at 250, 350, and 500 μm, taken with the Keck I Low Resolution Imaging Spectrometer and the Keck II DEep Imaging Multi-Object Spectrograph. The redshift distribution of these SPIRE sources from the Herschel Multitiered Extragalactic Survey peaks at z = 0.85, with 731 sources at z spec)) = 0.29) than is seen in non-infrared selected samples, likely due to enhanced star formation rates and dust obscuration in infrared-selected galaxies. The infrared data are used to directly measure integrated infrared luminosities and dust temperatures independent of radio or 24 μm flux densities. By probing the dust spectral energy distribution (SED) at its peak, we estimate that the vast majority (72%-83%) of z IR∝(1 + z)–0.30±0.02 at z > 0 and demonstrates the growing importance of dusty starbursts for galaxy evolution studies and the build-up of stellar mass throughout cosmic time.

  10. HI Recycling Formation of Tidal Dwarf Galaxies

    Duc, P A; Duc, Pierre-Alain; Brinks, Elias

    2000-01-01

    Galactic collisions trigger a number of phenomena, such as transportation inward of gas from distances of up to kiloparsecs from the center of a galaxy to the nuclear region, fuelling a central starburst or nuclear activity. The inverse process, the ejection of material into the intergalactic medium by tidal forces, is another important aspect and can be studied especially well through detailed HI observations of interacting systems which have shown that a large fraction of the gaseous component of colliding galaxies can be expelled. Part of this tidal debris might fall back, be dispersed throughout the intergalactic medium or recondense to form a new generation of galaxies: the so-called tidal dwarf galaxies. The latter are nearby examples of galaxies in formation. The properties of these recycled objects are reviewed here and different ways to identify them are reviewed.

  11. The host galaxy of GRB 990712

    Christensen, L.; Hjorth, J.; Gorosabel, J.;

    2004-01-01

    We present a comprehensive study of the z = 0.43 host galaxy of GRB 990712, involving ground-based photometry, spectroscopy, and HST imaging. The broad-band UBVRIJHKs photometry is used to determine the global spectral energy distribution (SED) of the host galaxy. Comparison with that of known...... galaxy types shows that the host is similar to a moderately kreddened starburst galaxy with a young stellar population. The estimated internal extinction in the host is A(V) = 0.15 +/- 0.1 and the star-formation rate (SFR) from the UV continuum is 1.3 +/- 0.3 M-circle dot yr(-1) (not corrected for the...... effects of extinction). Other galaxy template spectra than starbursts failed to reproduce the observed SED. We also present VLT spectra leading to the detection of Halpha from the GRB host galaxy. A SFR of 2.8 +/- 0.7 M-circle dot yr(-1) is inferred from the Halpha line flux, and the presence of a young...

  12. Probing the chemical abundances in distant galaxies with 10 m class telescopes

    Contini, T.

    2003-01-01

    The determination of chemical abundances in star-forming galaxies and the study of their evolution on cosmological timescales are powerful tools for understanding galaxy formation and evolution. This contribution presents the latest results in this domain. We show that detailed studies of chemical abundances in UV-selected, HII and starburst nucleus galaxies, together with the development of new chemical evolution models, put strong constraints on the evolutionary stage of these objects in te...

  13. Modelling nova populations in galaxies

    Chen, Hai-Liang; Woods, T. E.; Yungelson, L. R.; Gilfanov, M.; Han, Zhanwen

    2016-05-01

    Theoretical modelling of the evolution of classical and recurrent novae plays an important role in studies of binary evolution, nucleosynthesis and accretion physics. However, from a theoretical perspective the observed statistical properties of novae remain poorly understood. In this paper, we have produced model populations of novae using a hybrid binary population synthesis approach for differing star formation histories (SFHs): a starburst case (elliptical-like galaxies), a constant star formation rate case (spiral-like galaxies) and a composite case (in line with the inferred SFH for M31). We found that the nova rate at 10 Gyr in an elliptical-like galaxy is ˜10-20 times smaller than a spiral-like galaxy with the same mass. The majority of novae in elliptical-like galaxies at the present epoch are characterized by low-mass white dwarfs (WDs), long decay times, relatively faint absolute magnitudes and long recurrence periods. In contrast, the majority of novae in spiral-like galaxies at 10 Gyr have massive WDs, short decay times, are relatively bright and have short recurrence periods. The mass-loss time distribution for novae in our M31-like galaxy is in agreement with observational data for Andromeda. However, it is possible that we underestimate the number of bright novae in our model. This may arise in part due to the present uncertainties in the appropriate bolometric correction for novae.

  14. QUALITATIVE INTERPRETATION OF GALAXY SPECTRA

    We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is for general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means-based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7, thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to H II galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. We compare the mean ages of the stellar populations with those inferred using the code STARLIGHT. We also examine the estimated gas-phase metallicity with the metallicities obtained using electron-temperature-based methods. A number of byproducts follow from the analysis. There is a tight correlation between the age of the stellar population and the metallicity of the gas, which is stronger than the correlations between galaxy mass and stellar age, and galaxy mass and gas metallicity. The galaxy spectra are known to follow a one-dimensional sequence, and we identify the luminosity-weighted mean stellar age as the affine parameter that describes the sequence. All ASK classes happen to have a significant fraction of old stars, although spectrum-wise they are outshined by the youngest populations. Old stars are metal-rich or metal-poor depending on whether they reside in passive galaxies or in star-forming galaxies.

  15. QUALITATIVE INTERPRETATION OF GALAXY SPECTRA

    Sanchez Almeida, J.; Morales-Luis, A. B. [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Terlevich, R.; Terlevich, E. [Instituto Nacional de Astrofisica, Optica y Electronica, Tonantzintla, Puebla (Mexico); Cid Fernandes, R., E-mail: jos@iac.es, E-mail: abml@iac.es, E-mail: rjt@ast.cam.ac.uk, E-mail: eterlevi@inaoep.mx, E-mail: cid@astro.ufsc.br [Departamento de Fisica-CFM, Universidade Federal de Santa Catarina, P.O. Box 476, 88040-900 Florianopolis, SC (Brazil)

    2012-09-10

    We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is for general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means-based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7, thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to H II galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. We compare the mean ages of the stellar populations with those inferred using the code STARLIGHT. We also examine the estimated gas-phase metallicity with the metallicities obtained using electron-temperature-based methods. A number of byproducts follow from the analysis. There is a tight correlation between the age of the stellar population and the metallicity of the gas, which is stronger than the correlations between galaxy mass and stellar age, and galaxy mass and gas metallicity. The galaxy spectra are known to follow a one-dimensional sequence, and we identify the luminosity-weighted mean stellar age as the affine parameter that describes the sequence. All ASK classes happen to have a significant fraction of old stars, although spectrum-wise they are outshined by the youngest populations. Old stars are metal-rich or metal-poor depending on whether they reside in passive galaxies or in star-forming galaxies.

  16. Over half of the far-infrared background light comes from galaxies at z >= 1.2

    Devlin, Mark J; Aretxaga, Itziar; Bock, James J; Chapin, Edward L; Griffin, Matthew; Gundersen, Joshua O; Halpern, Mark; Hargrave, Peter C; Hughes, David H; Klein, Jeff; Marsden, Gaelen; Martin, Peter G; Mauskopf, Philip; Moncelsi, Lorenzo; Netterfield, Calvin B; Ngo, Henry; Olmi, Luca; Pascale, Enzo; Patanchon, Guillaume; Rex, Marie; Scott, Douglas; Semisch, Christopher; Thomas, Nicholas; Truch, Matthew D P; Tucker, Carole; Tucker, Gregory S; Viero, Marco P; Wiebe, Donald V; 10.1038/nature07918

    2009-01-01

    Submillimetre surveys during the past decade have discovered a population of luminous, high-redshift, dusty starburst galaxies. In the redshift range 1 = 1.2 accounting for 70 per cent of it. As expected, at the longest wavelengths the signal is dominated by ultraluminous galaxies at z > 1.

  17. The Circumnuclear Environment of IRAS 20551-4250: A Case Study of AGN/Starburst Connection for JWST

    E. Sani

    2012-01-01

    Full Text Available We present a general review of the current knowledge of IRAS 20551-4250 and its circumnuclear environment. This Ultraluminous Infrared Galaxy is one of the most puzzling sources of its class in the nearby Universe: the near-IR spectrum is typical of a galaxy experiencing a very intense starburst, but a highly obscured active nucleus is identified beyond ~5 μm and possibly dominates the mid-IR energy output of the system. At longer wavelengths star formation is again the main driver of the global spectral shape and features. We interpret all the available IR diagnostics in the framework of simultaneous black hole growth and star formation and discuss the key properties that make this source an ideal laboratory for the forthcoming James Webb Space Telescope.

  18. Peering into the heart of the M82 starburst: Type II supernova remnants and a possible relic GRB?

    Fenech, Danielle Marie; Beswick, Robert; Muxlow, Tom; Argo, Megan

    2015-08-01

    M82 is considered the archetypal starburst galaxy and at a distance of ~3.6 Mpc is one of the closest examples of its kind. It therefore provides a unique opportunity to study a star-forming environment in detail and particularly the discrete products of star-formation such as supernova remnants (SNR) and HII regions. Supernovae and supernova remnants play an important role in the feedback of energy and material into the surrounding interstellar medium as evidenced in M82 by the galactic superwind driven by the numerous supernovae, SNR and massive stellar winds.Radio observations can be used to see into the core of the star-forming region in the centre of M82 as they are unaffected by the gas and dust associated with such an intense starburst environment. Since their discovery in the 1970s, radio observations have been used to study and monitor the evolution of the ~100 supernova remnants at the heart of this galaxy.We present multi-epoch millarcsecond resolution images of the most compact supernova remnants in M82, spanning 25 years of evolution. In particular, we will discuss one of the quintessential SNR 43.31+59.2 as well as the unusual object 41.95+57.5 and its potential as a GRB afterglow.

  19. Wing galaxies: A formation mechanism of the clumpy irregular galaxy Markarian 297

    Taniguchi, Yoshiaki; Noguchi, Masafumi

    1990-11-01

    In order to contribute to an understanding of collision-induced starburst activities, the authors present a detailed case study on the starburst galaxy Markarian 297 (= NGC 6052 = Arp 209; hereafter Mrk 297). This galaxy is classified as a clumpy irregular galaxy (CIG) according to its morphological properties (cf. Heidmann, 1987). Two major clumps and many small clumps are observed in the entire region of Mrk 297 (Hecquet, Coupinot, and Maucherat 1987). The overall morphology of Mrk 297 is highly chaotic and thus it seems difficult to determine possible orbits of galaxy-galaxy collision. However, the authors have serendipitously found a possible orbit during a course of numerical simulations for a radial-penetration collision between galaxies. The radial-penetration collision means that an intruder penetrates a target galaxy radially passing by its nucleus. This kind of collision is known to explain a formation mechanism of ripples around disk galaxies (Wallin and Struck-Marcell 1988). Here, the authors show that the radial-penetration collision between galaxies successfully explains both overall morphological and kinematical properties of Mrk 297. The authors made two kinds of numerical simulations for Mrk 297. One is N-body (1x104 particles) simulations in which effects of self gravity of the stellar disk are taken into account. These simulations are used to study detailed morphological feature of Mrk 297. The response of gas clouds are also investigated in order to estimate star formation rates in such collisions. The other is test-particle simulations, which are utilized to obtain a rough picture of Mrk 297 and to analyze the velocity field of Mrk 297. The techniques of the numerical simulations are the same as those in Noguchi (1988) and Noguchi and Ishibashi (1986). In the present model, an intruding galaxy with the same mass of a target galaxy moves on a rectilinear orbit which passes the center of the target.

  20. Wing galaxies: A formation mechanism of the clumpy irregular galaxy Markarian 297

    Taniguchi, Yoshiaki; Noguchi, Masafumi

    1990-01-01

    In order to contribute to an understanding of collision-induced starburst activities, the authors present a detailed case study on the starburst galaxy Markarian 297 (= NGC 6052 = Arp 209; hereafter Mrk 297). This galaxy is classified as a clumpy irregular galaxy (CIG) according to its morphological properties (cf. Heidmann, 1987). Two major clumps and many small clumps are observed in the entire region of Mrk 297 (Hecquet, Coupinot, and Maucherat 1987). The overall morphology of Mrk 297 is highly chaotic and thus it seems difficult to determine possible orbits of galaxy-galaxy collision. However, the authors have serendipitously found a possible orbit during a course of numerical simulations for a radial-penetration collision between galaxies. The radial-penetration collision means that an intruder penetrates a target galaxy radially passing by its nucleus. This kind of collision is known to explain a formation mechanism of ripples around disk galaxies (Wallin and Struck-Marcell 1988). Here, the authors show that the radial-penetration collision between galaxies successfully explains both overall morphological and kinematical properties of Mrk 297. The authors made two kinds of numerical simulations for Mrk 297. One is N-body (1x10(exp 4) particles) simulations in which effects of self gravity of the stellar disk are taken into account. These simulations are used to study detailed morphological feature of Mrk 297. The response of gas clouds are also investigated in order to estimate star formation rates in such collisions. The other is test-particle simulations, which are utilized to obtain a rough picture of Mrk 297 and to analyze the velocity field of Mrk 297. The techniques of the numerical simulations are the same as those in Noguchi (1988) and Noguchi and Ishibashi (1986). In the present model, an intruding galaxy with the same mass of a target galaxy moves on a rectilinear orbit which passes the center of the target.

  1. The clustering properties of faint galaxies

    Infante, L; Infante, L; Pritchet, C J

    1994-01-01

    The two-point angular correlation function of galaxies, \\wte, has been computed from a new survey of faint galaxies covering a 2 deg^2 area near the North Galactic Pole. This survey, which is complete to limiting magnitudes \\jmag=24 and \\fmag=23, samples angular scales as large as 1\\degpoint5. Faint galaxies are found to be more weakly clustered (by a factor of at least two) compared to galaxies observed locally. Clustering amplitudes are closer to model predictions in the red than in the blue. The weak clustering of faint galaxies cannot be explained by any plausible model of clustering evolution with redshift. However, one possible explanation of the clustering properties of intermediate redshift galaxies is that they resemble those of starburst galaxies and H II region galaxies, which are observed locally to possess weak clustering amplitudes. Our clustering amplitudes are also similar to those of nearby late-type galaxies, which are observed to be more weakly clustered than early-type galaxies A simple, s...

  2. Ionizing photon budget: constraints from galaxies

    Östlin, Göran

    2015-08-01

    I will discuss the the production and propagation of ionizing photons in galaxies. Multi wavelength HST imaging and spectroscopy of local starbursts, including candidate Lyman continuum leakers, from the UV to the i-band plus Halpha and Hbeta are used to investigate where ionizing protons are produced and absorbed. We add IFU data, e.g. from MUSE, to further constrain the optical depth to Lyman continuum photons. I will further discuss rest frame UV observations of galaxies at higher redshifts, and their implications for the ionizing photon budget.

  3. Deep galaxy count predictions in the radio, infrared, and X-ray spectral bands

    Treyer, Marie-Agnes; Silk, Joseph

    1993-01-01

    The existence of a dominant population of strongly evolving starburst sources at moderate redshift is a plausible explanation for the excess number of faint blue galaxies detected in deep sky surveys. Multiwavelength observations at faint magnitudes would allow the existence of such a population to be confirmed. We use observed luminosity correlations and physical properties of known starburst galaxies to predict their contribution to the deep radio, infrared, and X-ray counts, as well as to the diffuse extragalactic background radiation in these various spectral bands.

  4. The Evidence for Massive Star Formation in Early-Type Spiral Galaxies

    Hameed, S A; Hameed, Salman; Devereux, Nick

    1997-01-01

    A recent analysis of the IRAS database indicates that the massive star formation rates in early-type (Sa-Sab) spirals are comparable to the massive star formation rates in late-type spirals. $H\\alpha$ imaging of some of the infrared luminous early-type spirals reveals two types of galaxies. One type shows clear signs of interaction, whereas the other type appears to host a nuclear starburst. The occurence of nuclear starbursts in early-type spirals may be related to the propensity for such galaxies to also host Seyfert nuclei. The evidence for interactions suggests that early-type spirals are evolving in the current epoch.

  5. Scaling relations of metallicity, stellar mass, and star formation rate in metal-poor starbursts: II. Theoretical models

    Magrini, Laura; Galli, Daniele; Schneider, Raffaella; Bianchi, Simone; Maiolino, Roberto; Romano, Donatella; Tosi, Monica; Valiante, Rosa

    2012-01-01

    Scaling relations of metallicity (O/H), star formation rate (SFR), and stellar mass give important insight on galaxy evolution. They are obeyed by most galaxies in the Local Universe and also at high redshift. In a companion paper, we compiled a sample of ~1100 galaxies from redshift 0 to ~3, spanning almost two orders of magnitude in metal abundance, a factor of $\\sim10^6$ in SFR, and of ~10^5 in stellar mass. We have characterized empirically the star-formation "main sequence" (SFMS) and the mass-metallicity relation (MZR) for this sample, and also identified a class of low-metallicity starbursts, rare locally but more common in the distant universe. These galaxies deviate significantly from the main scaling relations, with high SFR and low metal content for a given M*. In this paper, we model the scaling relations and explain these deviations from them with a set of multi-phase chemical evolution models based on the idea that, independently of redshift, initial physical conditions in a galaxy's evolutionar...

  6. Resolving the buried starburst in Arp299

    Charmandaris, V; Gull, G

    2002-01-01

    We present new 37.7 micron far-infrared imaging of the infrared luminous (L_IR ~ 5.16x10^{11} L_sun) interacting galaxy Arp299 (= IC694 + NGC3690). We show that the 38 micron flux, like the 60 and 100 micron emission, traces the luminosity of star forming galaxies, but at considerably higher spatial resolution. Our data establish that the major star formation activity of the galaxy originates from a point source in its eastern component, IC694, which is inconspicuous in the optical, becoming visible only at the near and mid-infrared. We find that IC694 is two times more luminous than NGC3690, contributing to more than 46% of the total energy output of the system at this wavelength. The spectral energy distribution of the different components of the system clearly shows that IC694, has 6 times the infrared luminosity of M82 and it is the primary source responsible for the bolometric luminosity of Arp299.

  7. Modelling nova populations in galaxies

    Chen, Hai-Liang; Yungelson, L R; Gilfanov, M; Han, Zhanwen

    2016-01-01

    Theoretical modelling of the evolution of classical and recurrent novae plays an important role in studies of binary evolution, nucleosynthesis and accretion physics. However, from a theoretical perspective the observed statistical properties of novae remain poorly understood. In this paper, we have produced model populations of novae using a hybrid binary population synthesis approach for differing star formation histories (SFHs): a starburst case (elliptical-like galaxies), a constant star formation rate case (spiral-like galaxies) and a composite case (in line with the inferred SFH for M31). We found that the nova rate at 10\\;Gyr in an elliptical-like galaxy is $\\sim 10-20$ times smaller than a spiral-like galaxy with the same mass. The majority of novae in elliptical-like galaxies at the present epoch are characterized by low mass white dwarfs (WDs), long decay times, relatively faint absolute magnitudes and long recurrence periods. In contrast, the majority of novae in spiral-like galaxies at 10\\;Gyr hav...

  8. Qualitative interpretation of galaxy spectra

    Almeida, J Sanchez; Terlevich, E; Fernandes, R Cid; Morales-Luis, A B

    2012-01-01

    We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis, and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is of general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7 (SDSS-DR7), thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to HII galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. A number of byprodu...

  9. Elliptical Galaxies and Bulges of Disk Galaxies: Summary of Progress and Outstanding Issues

    Kormendy, John

    2015-01-01

    This is the summary chapter of a review book on galaxy bulges. Bulge properties and formation histories are more varied than those of ellipticals. I emphasize two advances: 1 - "Classical bulges" are observationally indistinguishable from ellipticals, and like them, are thought to form by major galaxy mergers. "Disky pseudobulges" are diskier and more actively star-forming (except in S0s) than are ellipticals. Theys are products of the slow ("secular") evolution of galaxy disks: bars and other nonaxisymmetries move disk gas toward the center, where it starbursts and builds relatively flat, rapidly rotating components. This secular evolution is a new area of galaxy evolution work that complements hierarchical clustering. 2 - Disks of high-redshift galaxies are unstable to the formation of mass clumps that sink to the center and merge - an alternative channel for the formation of classical bulges. I review successes and unsolved problems in the formation of bulges+ellipticals and their coevolution (or not) with...

  10. The Starburst Model for AGN: Past, Present & Future

    Fernandes, R. Cid

    1996-01-01

    It is now eleven years since Terlevich \\& Melnick first proposed an `AGN without black-holes' model, an idea which since then evolved into what is now called the starburst model for AGN. This model has been the subject of much debate in the last decade, with observational evidence both for and against it further fuelling the controversy. Can we after all these years reach a veredictum on whether starbursts can power AGN? This contribution tries to answer this question reviewing the main achie...

  11. Dusty star-forming galaxies at high redshift

    Far-infrared and submillimeter wavelength surveys have now established the important role of dusty, star-forming galaxies (DSFGs) in the assembly of stellar mass and the evolution of massive galaxies in the Universe. The brightest of these galaxies have infrared luminosities in excess of 1013L⊙ with implied star-formation rates of thousands of solar masses per year. They represent the most intense starbursts in the Universe, yet many are completely optically obscured. Their easy detection at submm wavelengths is due to dust heated by ultraviolet radiation of newly forming stars. When summed up, all of the dusty, star-forming galaxies in the Universe produce an infrared radiation field that has an equal energy density as the direct starlight emission from all galaxies visible at ultraviolet and optical wavelengths. The bulk of this infrared extragalactic background light emanates from galaxies as diverse as gas-rich disks to mergers of intense starbursting galaxies. Major advances in far-infrared instrumentation in recent years, both space-based and ground-based, has led to the detection of nearly a million DSFGs, yet our understanding of the underlying astrophysics that govern the start and end of the dusty starburst phase is still in nascent stage. This review is aimed at summarizing the current status of DSFG studies, focusing especially on the detailed characterization of the best-understood subset (submillimeter galaxies, who were summarized in the last review of this field over a decade ago, Blain et al., 2002), but also the selection and characterization of more recently discovered DSFG populations. We review DSFG population statistics, their physical properties including dust, gas and stellar contents, their environments, and current theoretical models related to the formation and evolution of these galaxies

  12. AGN Zoo and Classifications of Active Galaxies

    Mickaelian, Areg M.

    2015-07-01

    We review the variety of Active Galactic Nuclei (AGN) classes (so-called "AGN zoo") and classification schemes of galaxies by activity types based on their optical emission-line spectrum, as well as other parameters and other than optical wavelength ranges. A historical overview of discoveries of various types of active galaxies is given, including Seyfert galaxies, radio galaxies, QSOs, BL Lacertae objects, Starbursts, LINERs, etc. Various kinds of AGN diagnostics are discussed. All known AGN types and subtypes are presented and described to have a homogeneous classification scheme based on the optical emission-line spectra and in many cases, also other parameters. Problems connected with accurate classifications and open questions related to AGN and their classes are discussed and summarized.

  13. COLA. III. RADIO DETECTION OF ACTIVE GALACTIC NUCLEUS IN COMPACT MODERATE LUMINOSITY INFRARED GALAXIES

    We present results from 4.8 GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median LIR = 1011.01 Lsun) COLA sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (∼1021 W Hz-1) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.

  14. Radio and Mid-Infrared Properties of Compact Starbursts: Distancing Themselves from the Main Sequence

    Murphy, E J; Armus, L; Condon, J J; Evans, A S

    2013-01-01

    We investigate the relationship between 8.44\\,GHz brightness temperatures and 1.4 to 8.44\\,GHz radio spectral indices with 6.2\\,$\\mu$m polycyclic aromatic hydrocarbon (PAH) emission and 9.7\\,$\\mu$m silicate absorption features for a sample of 36 local luminous and ultra-luminous infrared galaxies. We find that galaxies having small 6.2\\,$\\mu$m PAH equivalent widths (EQWs), which signal the presence of weak PAH emission and/or an excess of very hot dust, also have flat spectral indices. The three active galactic nuclei (AGN) identified through their excessively large 8.44\\,GHz brightness temperatures are also identified as AGN via their small 6.2\\,$\\mu$m PAH EQWs. We also find that the flattening of the radio spectrum increases with increasing silicate optical depth, 8.44\\,GHz brightness temperature, and decreasing size of the radio source even after removing potential AGN, supporting the idea that compact starbursts show spectral flattening as the result of increased free-free absorption. These correlations a...

  15. Infrared Narrow-Band Tomography of the Local Starburst NGC 1569 with LBT/LUCIFER

    Pasquali, A; Zibetti, S; Ageorges, N; Seifert, W; Brandner, W; Rix, H -W; Juette, M; Knierim, V; Buschkamp, P; Feiz, C; Gemperlein, H; Germeroth, A; Hoffmann, R; Laun, W; Lederer, R; Lehmitz, M; Lenzen, R; Mall, U; Mandel, H; Mueller, P; Naranjo, V; Polsterer, K; Quirrenbach, A; Schaeffner, L; Storz, C; Weiser, P

    2011-01-01

    We used the near-IR imager/spectrograph LUCIFER mounted on the Large Binocular Telescope (LBT) to image, with sub-arcsec seeing, the local dwarf starburst NGC 1569 in the JHK bands and HeI 1.08 micron, [FeII] 1.64 micron and Brgamma narrow-band filters. We obtained high-quality spatial maps of HeI, [FeII] and Brgamma emission across the galaxy, and used them together with HST/ACS images of NGC 1569 in the Halpha filter to derive the two-dimensional spatial map of the dust extinction and surface star formation rate density. We show that dust extinction is rather patchy and, on average, higher in the North-West (NW) portion of the galaxy [E_g(B-V) = 0.71 mag] than in the South-East [E_g(B-V) = 0.57 mag]. Similarly, the surface density of star formation rate peaks in the NW region of NGC 1569, reaching a value of about 4 x 10^-6 M_sun yr^-1 pc^-2. The total star formation rate as estimated from the integrated, dereddened Halpha luminosity is about 0.4 M_sun yr^-1, and the total supernova rate from the integrated...

  16. ISM gas removal from starburst galxies and the premature death of star clusters

    Melioli, C

    2005-01-01

    Recent observational studies of the age distribution of star clusters in nearby merging galaxies and starburst (SB) galaxies indicate a premature death of the young clusters. The fate of an evolving star cluster crucially depends of its gas content. This behaves like a glue that helps to keep the star system gravitationally bound. In SB systems where the rate of supernovae (SNe) explosions is elevated one should expect an efficient heating of the gas and its complete removal which could then favor the rapid dissociation of the evolving star clusters. Based on a contemporaneous study of the dynamical evolution of the interstellar gas in SB environments (Melioli & de Gouveia Dal Pino 2004) where it has been considered also the presence of dense clouds that may inhibit the heating efficiency of the interstellar gas by the SNe, we have here computed the timescales for gas removal from young clusters embedded in these systems and found that they are consistent with the very short timescales for cluster dissolu...

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

    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.

  18. The mid-infrared appearance of the galactic mini-starburst W49A

    Stock, D. J.; Peeters, E.; Choi, W. D.-Y.; Shannon, M. J. [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada)

    2014-08-20

    The massive star-forming region W49A represents one of the largest complexes of massive star formation present in the Milky Way and contains at least 50 young massive stars still enshrouded in their natal molecular cloud. We employ Spitzer/Infrared Spectrometer spectral mapping observations of the northern part of W49A to investigate the mid-infrared (MIR) spatial appearance of the polycyclic aromatic hydrocarbon (PAH) bands, PAH plateau features, atomic lines, and continuum emission. We examine the spatial variations of the MIR emission components in slices through two of the ultra-compact-H II (UC-H II) regions. We find that the PAH bands reproduce known trends, with the caveat that the 6.2 μm PAH band seems to decouple from the other ionized PAH bands in some of the UC-H II regions—an effect previously observed only in one other object: the giant star forming region N66 in the Large Magellanic Cloud. Furthermore, we compare the nature of the emission surrounding W49A to that of 'diffuse' sightlines. It is found that the surrounding emission can be explained by line of sight emission and does not represent true 'diffuse' material. Additionally, we examine the MIR appearance of star formation on various scales from UC-H II regions to starburst galaxies, including a discussion of the fraction of PAH emission in the 8 μm IRAC filter. We find that the MIR appearance of W49A is that of a starburst on large scales, yet its individual components are consistent with other galactic H II regions.

  19. On the geometry and conformation of starburst dendrimers

    De Pádua, A B; Moraes, F; Padua, Antonio de; Moraes, Fernando

    1995-01-01

    In this work, we propose a geometrical model for the study of conformational properties of a starburst dendrimer with the topology of a truncated Bethe lattice. A convenient embedding of the Bethe lattice in the hyperbolic plane is used to study the architecture of the dendrimer. As results, we find an upper bound for the molecular size and the density profile.

  20. The mass-metallicity relation of interacting galaxies

    Michel-Dansac, L; Alonso, M S; Tissera, P

    2008-01-01

    We study the mass-metallicity relation of galaxies in pairs and in isolation taken from the SDSS-DR4 using the stellar masses and oxygen abundances derived by Tremonti et al. (2004). Close galaxy pairs, defined by projected separation r_p ~ 10^10 Msun/h) galaxies have a systematically lower metallicity, although with a smaller difference (-0.05 dex). Similar trends are obtained if g-band magnitudes are used instead of stellar masses. In minor interactions, we find that the less massive member is systematically enriched, while a galaxy in interaction with a comparable stellar mass companion shows a metallicity decrement with respect to galaxies in isolation. We argue that metal-rich starbursts triggered by a more massive component, and inflows of low metallicity gas induced by comparable or less massive companion galaxies, provide a natural scenario to explain our findings.

  1. Galaxy Zoo: Mergers - Dynamical models of interacting galaxies

    Holincheck, Anthony J.; Wallin, John F.; Borne, Kirk; Fortson, Lucy; Lintott, Chris; Smith, Arfon M.; Bamford, Steven; Keel, William C.; Parrish, Michael

    2016-06-01

    The dynamical history of most merging galaxies is not well understood. Correlations between galaxy interaction and star formation have been found in previous studies, but require the context of the physical history of merging systems for full insight into the processes that lead to enhanced star formation. We present the results of simulations that reconstruct the orbit trajectories and disturbed morphologies of pairs of interacting galaxies. With the use of a restricted three-body simulation code and the help of citizen scientists, we sample 105 points in parameter space for each system. We demonstrate a successful recreation of the morphologies of 62 pairs of interacting galaxies through the review of more than 3 million simulations. We examine the level of convergence and uniqueness of the dynamical properties of each system. These simulations represent the largest collection of models of interacting galaxies to date, providing a valuable resource for the investigation of mergers. This paper presents the simulation parameters generated by the project. They are now publicly available in electronic format at http://data.galaxyzoo.org/mergers.html. Though our best-fitting model parameters are not an exact match to previously published models, our method for determining uncertainty measurements will aid future comparisons between models. The dynamical clocks from our models agree with previous results of the time since the onset of star formation from starburst models in interacting systems and suggest that tidally induced star formation is triggered very soon after closest approach.

  2. PHYSICS OF COEVOLUTION OF GALAXIES AND SUPERMASSIVE BLACK HOLES

    Cen Renyue, E-mail: cen@astro.princeton.edu [Princeton University Observatory, Princeton, NJ 08544 (United States)

    2012-08-10

    A new physically based model for coevolution of galaxies and supermassive black holes (SMBHs) is presented. The evolutionary track starts with an event that triggers a significant starburst in the central region of a galaxy. In this model, the main SMBH growth takes place in the post-starburst phase, fueled by recycled gas from inner bulge stars in a self-regulated fashion on a timescale that is substantially longer than 100 Myr and at a diminishing Eddington ratio with time. We argue that the SMBH cannot gorge itself during the starburst phase, despite the abundant supply of cold gas, because star formation (SF) is a preferred mode of gas consumption over accretion to the central SMBH in such an environment. We also show that feedback from SF is at least as strong as that from an active galactic nucleus (AGN); thus, if SF is in need of being quenched, AGN feedback generally does not play the primary role. The predicted relation between SMBH mass and bulge mass/velocity dispersion is consistent with observations. A clear prediction is that early-type galaxy hosts of high-Eddington-rate AGNs are expected to be light blue to green in optical color, gradually evolving to the red sequences with decreasing AGN luminosity. A suite of falsifiable predictions and implications with respect to relationships between various types of galaxies, AGNs, and others are made. For those where comparisons to extant observations are possible, the model appears to be in good standing.

  3. PHYSICS OF COEVOLUTION OF GALAXIES AND SUPERMASSIVE BLACK HOLES

    A new physically based model for coevolution of galaxies and supermassive black holes (SMBHs) is presented. The evolutionary track starts with an event that triggers a significant starburst in the central region of a galaxy. In this model, the main SMBH growth takes place in the post-starburst phase, fueled by recycled gas from inner bulge stars in a self-regulated fashion on a timescale that is substantially longer than 100 Myr and at a diminishing Eddington ratio with time. We argue that the SMBH cannot gorge itself during the starburst phase, despite the abundant supply of cold gas, because star formation (SF) is a preferred mode of gas consumption over accretion to the central SMBH in such an environment. We also show that feedback from SF is at least as strong as that from an active galactic nucleus (AGN); thus, if SF is in need of being quenched, AGN feedback generally does not play the primary role. The predicted relation between SMBH mass and bulge mass/velocity dispersion is consistent with observations. A clear prediction is that early-type galaxy hosts of high-Eddington-rate AGNs are expected to be light blue to green in optical color, gradually evolving to the red sequences with decreasing AGN luminosity. A suite of falsifiable predictions and implications with respect to relationships between various types of galaxies, AGNs, and others are made. For those where comparisons to extant observations are possible, the model appears to be in good standing.

  4. Infrared studies of active galaxies

    IRAS observations of extragalactic objects are analyzed, supplemented by optical spectroscopy and 10 μm photometry. The relationship between various forms of activity in the nuclei of spiral galaxies and their mid- to far-infrared spectral energy distributions is explored. It is shown that more than 70% of galaxies with F60/F25 ≤ 3 are Seyferts, while the remainder have bright optical emission lines in their nuclear spectra. It is argued that most Seyferts are powered by their active nuclei at 25 μm, while there is some indication that Seyferts with large F60/F25 flux ratios are undergoing starbursts in the vicinity of their nuclei. The properties of a sample of bright, extragalactic IRAS sources are studied. A catalog containing total infrared and blue fluxes, distance estimates, recession velocities, and morphological classifications for these objects is presented. The brightest sources at mid- to far-infrared wavelengths are nearby, normal spiral galaxies; galaxies with disturbed or irregular morphology (often known as interacting galaxies); type 2 Seyferts; and dust-embedded type 1 Seyferts. All of these sources are dominated by thermal emission from dust. The dust in the peculiar, irregular, and Seyfert galaxies is exposed to a higher mean intensity of radiation. Moreover, these IR-active galaxies tend to have strong, compact nuclear sources at 11 μm, whether or not they contain a known Seyfert nucleus. The distinctive spectral behavior of IR-luminous galaxies is shown to result from the presence of compact, dust-dominated IR nuclear sources, which are the predominant cause of IR luminosities above 1011 L of sun

  5. Effects of AGN feedback on LCDM galaxies

    Lagos, Claudia del P; Padilla, Nelson D

    2008-01-01

    We study the effects of Active Galactic Nuclei (AGN) feedback on the formation and evolution of galaxies in a semi-analytic model of galaxy formation. This model is an improved version of the one described by Cora (2006), which now considers the growth of black holes (BHs) as driven by (i) gas accretion during merger-driven starbursts and mergers with other BHs, (ii) accretion during starbursts triggered by disc instabilities, and (iii) accretion of gas cooled from quasi-hydrostatic hot gas haloes. It is assumed that feedback from AGN operates in the later case. The model has been calibrated in order to reproduce observational correlations between BH mass and mass, velocity dispersion, and absolute magnitudes of the galaxy bulge. AGN feedback has a strong impact on reducing or even suppressing gas cooling, an effect that becomes important at lower redshifts. This phenomenon helps to reproduce the observed galaxy luminosity function (LF) in the optical and near IR bands at z=0, and the cosmic star formation ra...

  6. Molecular gas heating mechanisms, and star formation feedback in merger/starbursts: NGC 6240 and Arp 193 as case studies

    We used the SPIRE/FTS instrument aboard the Herschel Space Observatory to obtain the Spectral Line Energy Distributions (SLEDs) of CO from J = 4-3 to J = 13-12 of Arp 193 and NGC 6240, two classical merger/starbursts selected from our molecular line survey of local Luminous Infrared Galaxies (L IR ≥ 1011 L ☉). The high-J CO SLEDs are then combined with ground-based low-J CO, 13CO, HCN, HCO+, CS line data and used to probe the thermal and dynamical states of their large molecular gas reservoirs. We find the two CO SLEDs strongly diverging from J = 4-3 onward, with NGC 6240 having a much higher CO line excitation than Arp 193, despite their similar low-J CO SLEDs and L FIR/L CO, 1 –0, L HCN/L CO (J = 1-0) ratios (proxies of star formation efficiency and dense gas mass fraction). In Arp 193, one of the three most extreme starbursts in the local universe, the molecular SLEDs indicate a small amount (∼5%-15%) of dense gas (n ≥ 104 cm–3) unlike NGC 6240 where most of the molecular gas (∼60%-70%) is dense (n ∼ (104-105) cm–3). Strong star-formation feedback can drive this disparity in their dense gas mass fractions, and also induce extreme thermal and dynamical states for the molecular gas. In NGC 6240, and to a lesser degree in Arp 193, we find large molecular gas masses whose thermal states cannot be maintained by FUV photons from Photon-Dominated Regions. We argue that this may happen often in metal-rich merger/starbursts, strongly altering the initial conditions of star formation. ALMA can now directly probe these conditions across cosmic epoch, and even probe their deeply dust-enshrouded outcome, the stellar initial mass function averaged over galactic evolution.

  7. Star Formation in Nearby Isolated Galaxies

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

    2013-01-01

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

  8. ISM Properties of Local Luminous Infrared Galaxies

    Diaz-Santos, Tanio; Armus, Lee; Stierwalt, Sabrina; Elbaz, David; Malhotra, Sangeeta

    2015-08-01

    Luminous and Ultra-luminous Infrared Galaxies ((U)LIRGs) represent the most important galaxy population at redshifts z > 1 as they account for more than 50% of all star formation produced in the Universe at those epochs; and encompass what it is called the main-sequence (MS) of star-forming galaxies. Investigating their local counterparts -low luminosity LIRGs- is therefore key to understand the physical properties and phases of their inter-stellar medium (ISM) - a task that is rather challenging in the distant Universe. On the other hand, high-z star-bursting (out of the MS) systems, although small in number, account for a modest yet still significant fraction of the total energy production. Here I present far-IR line emission observations ([CII]158μm, [OI]63μm, [OIII]88μm and [NII]122μm) obtained with Herschel for two large samples of nearby LIRGs: The Great Observatories All-sky LIRG Survey (GOALS), a sample of more than 240 relatively cold LIRGs, and a survey of 30 LIRGs selected to have very warm mid- to far-IR colors, suggestive of an ongoing intense nuclear starburst and/or an AGN. Using photo-dissociation region (PDR) models we derive the basic characteristics of the ISM (ionization intensity and density) for both samples and study differences among systems as a function of AGN activity, merger stage, dust temperature, and compactness of the starburst - parameters that are thought to control the life cycle of galaxies moving in and out of the MS, locally and at high-z.

  9. Impact of the short-term luminosity evolution on luminosity function of star-forming galaxies

    Parnovsky, S L

    2015-01-01

    An evolution of luminosity of galaxies in emission lines or wavelength ranges in which they are sensitive to the star formation process is caused by burning out of the most massive O-class stars during a few million years after a starburst. We study the impact of this effect on the luminosity function (LF) of a sample of star-forming galaxies. We introduce several types of LFs: an initial LF after a starburst, current, time-averaged and sample ones. We find the relations between them in general and specify them in the case of the luminosity evolution law proposed for the luminous compact galaxies. We obtain the sample LF for the cases the initial one is described by the pure Schechter function or the log-normal distribution and analyze the properties of these LFs. As a result we get two new types of LFs to fit the LF of a sample of star-forming galaxies.

  10. Star formation laws in Luminous Infrared Galaxies. New observational constraints on models

    Garcia-Burillo, S; Alonso-Herrero, A; Gracia-Carpio, J; Pereira-Santaella, M; Colina, L; Planesas, P; Arribas, S

    2011-01-01

    The observational study of star formation relations in galaxies is central to unraveling the physical processes at work on local and global scales. We wish to expand the sample of extreme starbursts, represented by local LIRGs and ULIRGs, with high quality observations in the 1-0 line of HCN. We study if a universal law can account for the star formation relations observed for the dense molecular gas in normal star forming galaxies and extreme starbursts. We have used the IRAM 30m telescope to observe a sample of 19 LIRGs in the 1-0 lines of CO, HCN and HCO+. The analysis of the new data proves that the efficiency of star formation in the dense molecular gas (SFE-dense) of extreme starbursts is a factor 3-4 higher compared to normal galaxies. We find a duality in Kennicutt-Schmidt (KS) laws that is reinforced if we account for the different conversion factor for HCN (alpha-HCN) in extreme starbursts and for the unobscured star formation rate in normal galaxies. This result extends to the higher molecular dens...

  11. Galaxy Pairs in the Sloan Digital Sky Survey - III: Evidence of Induced Star Formation from Optical Colours

    Patton, David R; Simard, Luc; McConnachie, Alan W; Mendel, J Trevor

    2010-01-01

    We have assembled a large, high quality catalogue of galaxy colours from the Sloan Digital Sky Survey Data Release 7, and have identified 21,347 galaxies in pairs spanning a range of projected separations (r_p 60 h_{70}^{-1} kpc and \\Delta v 3000 km/s). These effects are also stronger in central (fibre) colours than in global colours, and are found primarily in low- to medium-density environments. Conversely, no such trends are seen in red galaxies, apart from a small reddening at small separations which may resu lt from residual errors with photometry in crowded fields. When interpreted in conjunction with a simple model of induced starbursts, these results are consistent with a scenario in which close peri-centre passages trigger induced star formation in the centres of galaxies which are sufficiently gas rich, after which time the galaxies gradually redden as they separate and their starbursts age.

  12. Measures of star formation rates from Infrared (Herschel) and UV (GALEX) emissions of galaxies in the HerMES fields

    Buat, V; Burgarella, D; Altieri, B; Amblard, A; Arumugam, V; Aussel, H; Babbedge, T; Blain, A; Bock, J; Boselli, A; Castro-Rodriguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Dwek, E; Eales, S; Elbaz, D; Fox, M; Franceschini, A; Gear, W; Glenn, J; Griffin, M; Halpern, M; Hatziminaoglou, E; Heinis, S; Ibar, E; Isaak, K; Ivison, R J; Lagache, G; Levenson, L; Lonsdale, C J; Lu, N; Madden, S; Maffei, B; Magdis, G; Mainetti, G; Marchetti, L; Morrison, G E; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Owen, F N; Page, M J; Pannella, M; Panuzzo, P; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rigopoulou, D; Rizzo, D; Roseboom, I G; Rowan-Robinson, M; Portal, M Sanchez; Schulz, B; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Strazzullo, V; Symeonidis, M; Trichas, M; Tugwell, K E; Vaccari, M; Valiante, E; Valtchanov, I; Vigroux, L; Wang, L; Ward, R; Wright, G; Xu, C K; Zemcov, M

    2010-01-01

    The reliability of infrared (IR) and ultraviolet (UV) emissions to measure star formation rates in galaxies is investigated for a large sample of galaxies observed with the SPIRE and PACS instruments on Herschel as part of the HerMES project. We build flux-limited 250 micron samples of sources at redshift z 10 ^{11} L_sun and 0.5< z<1 exhibit a mean dust attenuation A_UV about 0.7 mag lower than that found for their local counterparts, although with a large dispersion. Our galaxy samples span a large range of beta and L_IR/L_UV values which, for the most part, are distributed between the ranges defined by the relations found locally for starburst and normal star-forming galaxies. As a consequence the recipe commonly applied to local starbursts is found to overestimate the dust attenuation correction in our galaxy sample by a factor ~2-3 .

  13. Discovery of a z=0.65 Post-Starburst BAL Quasar in the DES Supernova Fields

    Mudd, Dale; Tie, Suk Sien; Lidman, Chris; McMahon, Richard; Banerji, Manda; Davis, Tamara; Peterson, Bradley; Sharp, Rob; Childress, Michael; Lewis, Geraint; Tucker, Brad; Yuan, Fang; Abbot, Tim; Abdalla, Filipe; Allam, Sahar; Benoit-Levy, Aurelien; Bertin, Emmanuel; Brooks, David; Rosell, A Camero; Kind, Matias Carrasco; Carretero, Jorge; da Costa, Luiz N; Desai, Shantanu; Diehl, Thomas; Eifler, Tim; Finley, David; Flaugher, Brenna; Glazebrook, Karl; Gruen, Daniel; Gruendl, Robert; Gutierrez, Gaston; Hinton, Samuel; Honscheid, Klaus; James, David; Kuehn, Kyler; Kuropatkin, Nikolav; Macaulay, Edward; Maia, M A G; Miquel, Ramon; Ogando, Ricardo; Plazas, Andres; Riel, Kevin; Sanchez, Eusebio; Santiago, Basillio; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Smith, R C; Soares-Santos, Marcelle; Sobreira, Flavia; Suchyta, Eric; Swanson, Molly; Tarle, Gregory; Thomas, Daniel; Uddin, Sved; Walker, Alistair; Zhang, Bonnie

    2016-01-01

    We present the discovery of a z=0.65 low-ionization broad absorption line (LoBAL) quasar in a post-starburst galaxy in data from the Dark Energy Survey (DES) and spectroscopy from the Australian Dark Energy Survey (OzDES). LoBAL quasars are a minority of all BALs, and rarer still is that this object also exhibits broad FeII (an FeLoBAL) and Balmer absorption. This is the first BAL quasar that has signatures of recently truncated star formation, which we estimate ended about 40 Myr ago. The characteristic signatures of an FeLoBAL require high column densities, which could be explained by the emergence of a young quasar from an early, dust-enshrouded phase, or by clouds compressed by a blast wave. The age of the starburst component is comparable to estimates of the lifetime of quasars, so if we assume the quasar activity is related to the truncation of the star formation, this object is better explained by the blast wave scenario.

  14. The luminosity function of the brightest galaxies in the IRAS survey

    Soifer, B. T.; Sanders, D. B.; Madore, B. F.; Neugebauer, G.; Persson, C. J.; Persson, S. E.; Rice, W. L.

    1987-01-01

    Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst galaxies, and more numerous than quasars at the same bolometric luminosity. The far infrared luminosity in the local universe is approximately 25% of the starlight output in the same volume.

  15. Scaling Relations of Starburst-Driven Galactic Winds

    Tanner, Ryan; Heitsch, Fabian

    2016-01-01

    Using synthetic absorption lines generated from 3D hydro-dynamical simulations we explore how the velocity of a starburst-driven galactic wind correlates with the star formation rate (SFR) and SFR density. We find strong correlations until the scaling relations flatten abruptly at a point set by the mass loading of the starburst. Below this point the scaling relation depends on the temperature regime being probed by the absorption line, not on the mass loading. The exact scaling relation depends on whether the maximum or mean velocity of the absorption line is used. We find that the outflow velocity of neutral gas is four to five times lower than the average velocity of the hottest gas, with the difference in velocity between the neutral and ionized gas increasing with gas ionization. Thus, absorption lines of neutral or low ionized gas will underestimate the outflow velocity of hot gas, severely underestimating outflow energetics.

  16. ANATOMY OF A POST-STARBURST MINOR MERGER: A MULTI-WAVELENGTH WFC3 STUDY OF NGC 4150

    We present a spatially resolved near-UV/optical study, using the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope, of NGC 4150, a sub-L*, early-type galaxy (ETG) of around 6 x 109 Msun, which has been observed as part of the WFC3 Early-Release Science Programme. Previous work indicates that this galaxy has a large reservoir of molecular hydrogen gas, exhibits a kinematically decoupled core (a likely indication of recent merging) and strong, central Hβ absorption (indicative of young stars). While relatively uninspiring in its optical image, the core of NGC 4150 shows ubiquitous near-UV emission and remarkable dusty substructure. Our analysis shows this galaxy to lie in the near-UV green valley, and its pixel-by-pixel photometry exhibits a narrow range of near-UV/optical colors that are similar to those of nearby E+A (post-starburst) galaxies and lie between those of M83 (an actively star-forming spiral) and the local quiescent ETG population. We parameterize the properties of the recent star formation (RSF; age, mass fraction, metallicity, and internal dust content) in the NGC 4150 pixels by comparing the observed near-UV/optical photometry to stellar models. The typical age of the RSF is around 0.9 Gyr, consistent with the similarity of the near-UV colors to post-starburst systems, while the morphological structure of the young component supports the proposed merger scenario. The typical RSF metallicity, representative of the metallicity of the gas fuelling star formation, is ∼0.3-0.5 Zsun. Assuming that this galaxy is a merger and that the gas is sourced mainly from the infalling companion, these metallicities plausibly indicate the gas-phase metallicity (GPM) of the accreted satellite. Comparison to the local mass-GPM relation suggests (crudely) that the mass of the accreted system is ∼3 x 108 Msun, making NGC 4150 a 1:20 minor merger. A summation of the pixel RSF mass fractions indicates that the RSF contributes ∼2%-3% of the stellar mass

  17. Faint Infrared-Excess Field Galaxies FROGs

    Moustakas, L A; Zepf, S E; Bunker, A J

    1997-01-01

    Deep near-infrared and optical imaging surveys in the field reveal a curious population of galaxies that are infrared-bright (I-K>4), yet with relatively blue optical colors (V-I20, is high enough that if placed at z>1 as our models suggest, their space densities are about one-tenth of phi-*. The colors of these ``faint red outlier galaxies'' (fROGs) may derive from exceedingly old underlying stellar populations, a dust-embedded starburst or AGN, or a combination thereof. Determining the nature of these fROGs, and their relation with the I-K>6 ``extremely red objects,'' has implications for our understanding of the processes that give rise to infrared-excess galaxies in general. We report on an ongoing study of several targets with HST & Keck imaging and Keck/LRIS multislit spectroscopy.

  18. Spectral decomposition of broad-line agns and host galaxies

    Vanden Berk, Daniel E.; Shen, Jiajian; /Penn State U., Astron. Astrophys.; Yip, Ching-Wa; /Pittsburgh U.; Schneider, Donald P.; /Penn State U., Astron. Astrophys.; Connolly,; /Pittsburgh U.; Burton, Ross E.; /Pittsburgh U. /Case Western Reserve U.; Jester, Sebastian; /Fermilab; Hall, Patrick B.; /York U., Canada; Szalay, Alex S.; /Johns Hopkins; Brinkmann, John; /Apache Point Observ.

    2005-09-01

    Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification. We show how the accuracy of the decomposition depends upon S/N, host galaxy fraction, and the galaxy class. Based on the eigencoefficients, the sample of SDSS broad-line AGN host galaxies spans a wide range of spectral types, but the distribution differs significantly from inactive galaxies. In particular, post-starburst activity appears to be much more common among AGN host galaxies. The luminosities of the hosts are much higher than expected for normal early-type galaxies, and their colors become increasingly bluer than early-type galaxies with increasing host luminosity. Most of the AGNs with detected hosts are emitting at between 1% and 10% of their estimated Eddington luminosities, but the sensitivity of the technique usually does not extend to the Eddington limit. There are mild correlations among the AGN and host galaxy eigencoefficients, possibly indicating a link between recent star formation and the onset of AGN activity. The catalog of spectral reconstruction parameters is available as an electronic table.

  19. Starburst Driven Galactic Superbubbles Radiating to 10 K

    Tanner, Ryan; Heitsch, Fabian

    2015-01-01

    Our three-dimensional hydro-dynamical simulations of starbursts examine the formation of superbubbles over a range of driving luminosities and mass loadings which determine superbubble growth and wind velocity. From this we determine the relationship between the velocity of a galactic wind and the power of the starburst. We find a threshold for the formation of a wind, above which the speed of the wind is not affected by grid resolution or the temperature floor of our radiative cooling. We investigate the effect two different temperature floors in our radiative cooling prescription have on wind kinematics and content. We find that cooling to $10$ K instead of to $10^4$ K increases the mass fraction of cold neutral and hot X-ray gas in the galactic wind while halving that in warm H$\\alpha$. Our simulations show the mass of cold gas transported into the lower halo does not depend on the starburst strength. Optically bright filaments form at the edge of merging superbubbles, or where a cold dense cloud has been ...

  20. Measures of cosmic-ray energy densities in galaxies

    Persic, Massimo

    2012-01-01

    The energy density of cosmic-ray protons (CRp) in star-forming galaxies can be estimated from (i) neutral-pion--decay gamma-ray emission, (ii) synchrotron radio emission, and (iii) supernova rates. For most of the galaxies for which values of all these quantities are known, the three methods yield consistent CRp energy density estimates, ranging from O(0.1) eV/cm3 in galaxies with low star-formation rates, to O(100) eV/cm3 in galaxies with high star-formation rates. The only cases for which the methods do not agree are the composite starburst/Seyfert2 galaxy NGC1068, whose gamma-ray emission originates in black-hole accretion rather than star formation, and the Small Magellanic Cloud, where the discrepancy between measured and estimated CRp energy density may be due to a small CR confinement volume.

  1. The Lyman-alpha signature of the first galaxies

    Smith, Aaron; Safranek-Shrader, Chalence; Bromm, Volker; Milosavljević, Miloš

    2014-01-01

    We present the Cosmic Lyman-$\\alpha$ Transfer code (COLT), a massively parallel Monte-Carlo radiative transfer code, to simulate Lyman-$\\alpha$ (Ly$\\alpha$) resonant scattering through neutral hydrogen as a probe of the first galaxies. We explore the interaction of centrally produced Ly$\\alpha$ radiation with the host galactic environment. Ly$\\alpha$ photons emitted from the luminous starburst region escape with characteristic features in the line profile depending on the density distribution...

  2. Star formation rates from [C II] 158 μm and mid-infrared emission lines for starbursts and active galactic nuclei

    Sargsyan, L.; Lebouteiller, V.; Weedman, D.; Barry, D.; Spoon, H. [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States); Samsonyan, A. [Byurakan Astrophysical Observatory, Byurakan 0213 (Armenia); Bernard-Salas, J. [Department of Physical Sciences, Open University, Milton Keynes MK7 6AA (United Kingdom); Houck, J., E-mail: sargsyan@isc.astro.cornell.edu, E-mail: dweedman@isc.astro.cornell.edu [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States)

    2014-07-20

    A summary is presented for 130 galaxies observed with the Herschel Photodetector Array Camera and Spectrometer instrument to measure fluxes for the [C II] 158 μm emission line. Sources cover a wide range of active galactic nucleus to starburst classifications, as derived from polycyclic aromatic hydrocarbon strength measured with the Spitzer Infrared Spectrograph. Redshifts from [C II] and line to continuum strengths (equivalent width (EW) of [C II]) are given for the full sample, which includes 18 new [C II] flux measures. Calibration of L([C II)]) as a star formation rate (SFR) indicator is determined by comparing [C II] luminosities with mid-infrared [Ne II] and [Ne III] emission line luminosities; this gives the same result as determining SFR using bolometric luminosities of reradiating dust from starbursts: log SFR = log L([C II)]) – 7.0, for SFR in M{sub ☉} yr{sup –1} and L([C II]) in L{sub ☉}. We conclude that L([C II]) can be used to measure SFR in any source to a precision of ∼50%, even if total source luminosities are dominated by an active galactic nucleus (AGN) component. The line to continuum ratio at 158 μm, EW([C II]), is not significantly greater for starbursts (median EW([C II]) = 1.0 μm) compared to composites and AGNs (median EW([C II]) = 0.7 μm), showing that the far-infrared continuum at 158 μm scales with [C II] regardless of classification. This indicates that the continuum at 158 μm also arises primarily from the starburst component within any source, giving log SFR = log νL{sub ν}(158 μm) – 42.8 for SFR in M{sub ☉} yr{sup –1} and νL{sub ν}(158 μm) in erg s{sup –1}.

  3. Anatomy of a post-starburst minor merger: a multi-wavelength WFC3 study of NGC 4150

    Crockett, R Mark; Silk, Joseph I; Whitmore, Bradley C; O'Connell, Robert W; Mutchler, Max; Balick, Bruce; Bond, Howard E; Calzetti, Daniela; Carollo, C Marcella; Disney, Michael J; Dopita, Michael A; Frogel, Jay A; Hall, Donald N B; Holtzman, Jon A; Kimble, Randy A; McCarthy, Patrick J; Paresce, Francesco; Saha, Abhijit; Trauger, John T; Walker, Alistair R; Windhorst, Rogier A; Young, Erick T; Jeong, Hyunjin; Yi, Sukyoung K

    2010-01-01

    (Abridged) We present a spatially-resolved near-UV/optical study of NGC 4150, using the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. Previous studies of this early-type galaxy (ETG) indicate that it has a large reservoir of molecular gas, exhibits a kinematically decoupled core (likely indication of recent merging) and strong, central H_B absorption (indicative of young stars). The core of NGC 4150 shows ubiquitous near-UV emission and remarkable dusty substructure. Our analysis shows this galaxy to lie in the near-UV green valley, and its pixel-by-pixel photometry exhibits a narrow range of near-UV/optical colours that are similar to those of nearby E+A (post-starburst) galaxies. We parametrise the properties of the recent star formation (age, mass fraction, metallicity and internal dust content) in the NGC 4150 pixels by comparing the observed near-UV/optical photometry to stellar models. The typical age of the recent star formation (RSF) is around 0.9 Gyrs, consistent with the similarity...

  4. A Panchromatic Survey of Post-starburst Mergers: searching for feedback

    De Propris, Roberto

    2014-01-01

    We consider the morphology, stellar populations, structure and AGN activity of 10 post-starburst (K+A) galaxies with HST observations, full spectral coverage in the optical, spectral energy distributions from 0.2 to 160 $\\mu$m, X-ray and radio data. Our results show that the PSG phenomenon is related to mergers and interactions, and that star formation was likely triggered during close passes prior to final coalescence. We performed a detailed qualitative analysis of the observed light distribution, including low-surface brightness tidal features and color profiles, in high-resolution multi-band imaging with HST. We find evidence that star formation was centrally concentrated and that quenching took place from the inside-out, consistent with the occurrence of a feedback episode. Most of our PSGs contain massive bulges and therefore should host supermassive black holes. We search for AGN activity in spectra (line ratios), optical variability, X-ray emission at 0.5--7.0 KeV and radio emission at 20cm: all four ...

  5. 3-D Hydrodynamical Simulations of radiative cooling SNRs-clouds interactions: an application to Starburst Environments

    Melioli, C; Raga, A

    2005-01-01

    Most galaxies present supernova shock fronts interacting with a cloudy interstellar medium. Particularly, in this work we are interested to study the by-products of SNR-clouds in a starburst (SB) system. Due to the high SN rate in this environment, a cloud may be shocked more than once by SNRs. These interactions can have an important role in the recycling of matter from the clouds to the ISM and vice-versa. Their study is also relevant to understand the evolution of the ISM density and the structure of the clouds embedded in it. In the present work, we have focused our attention on the global effects of the interactions between clouds and SN shock waves in the ISM of SB environments, and performed 3-D radiative cooling hydrodynamical simulations with the adaptive YGUAZU grid code. We have also considered the effects of the photo-evaporation due to the presence of a high number of UV photons from hot stars and supernovae (SNe). The results have shown that, in the presence of radiative cooling, instead of an e...

  6. A far-IR view of the starburst driven superwind in NGC 2146

    Kreckel, K; Groves, B; Lyubenova, M; Diaz-Santos, T; Schinnerer, E; Appleton, P; Croxall, K V; Dale, D A; Hunt, L K; Beirao, P; Bolatto, A D; Calzetti, D; Meyer, J Donovan; Draine, B T; Hinz, J; Kennicutt, R C; Meidt, S; Murphy, E J; Smith, J D T; Tabatabaei, F S; Walter, F

    2014-01-01

    NGC 2146, a nearby luminous infrared galaxy (LIRG), presents evidence for outflows along the disk minor axis in all gas phases (ionized, neutral atomic and molecular). We present an analysis of the multi-phase starburst driven superwind in the central 5 kpc as traced in spatially resolved spectral line observations, using far-IR Herschel PACS spectroscopy, to probe the effects on the atomic and ionized gas, and optical integral field spectroscopy to examine the ionized gas through diagnostic line ratios. We observe an increased ~250 km/s velocity dispersion in the [OI] 63 micron, [OIII] 88 micron, [NII] 122 micron and [CII] 158 micron fine-structure lines that is spatially coincident with high excitation gas above and below the disk. We model this with a slow ~200 km/s shock and trace the superwind to the edge of our field of view 2.5 kpc above the disk. We present new SOFIA 37 micron observations to explore the warm dust distribution, and detect no clear dust entrainment in the outflow. The stellar kinematic...

  7. MAMBO 1.2 mm OBSERVATIONS OF LUMINOUS STARBURSTS AT z ∼ 2 IN THE SWIRE FIELDS

    We report on-off pointed MAMBO observations at 1.2 mm of 61 Spitzer-selected star-forming galaxies from the Spitzer Wide Area Infrared Extragalactic Legacy survey (SWIRE). The sources are selected on the basis of bright 24 μm fluxes (f 24μm > 0.4 mJy) and of stellar dominated near-infrared spectral energy distributions in order to favor z ∼ 2 starburst galaxies. The average 1.2 mm flux for the whole sample is 1.5 ± 0.2 mJy. Our analysis focuses on 29 sources in the Lockman Hole field where the average 1.2 mm flux (1.9 ± 0.3 mJy) is higher than in other fields (1.1 ± 0.2 mJy). The analysis of the multiwavelength spectral energy distributions indicates that these sources are starburst galaxies with far-infrared luminosities from 1012 to 1013.3 L sun, and stellar masses of ∼0.2-6 x 1011 M sun. Compared to submillimeter selected galaxies (SMGs), the SWIRE-MAMBO sources are among those with the largest 24 μm/1.2 mm flux ratios. The origin of such large ratios is investigated by comparing the average mid-infrared spectra and the stacked far-infrared spectral energy distributions of the SWIRE-MAMBO sources and of SMGs. The mid-infrared spectra, available for a handful of sources, exhibit strong polycyclic aromatic hydrocarbon (PAH) features, and a warm dust continuum. The warm dust continuum contributes ∼34% of the mid-infrared emission, and is likely associated with an AGN component. This contribution is consistent with what is found in SMGs. The large 24 μm/1.2 mm flux ratios are thus not due to AGN emission, but rather to enhanced PAH emission compared to SMGs. The analysis of the stacked far-infrared fluxes yields warmer dust temperatures than typically observed in SMGs. Our selection favors warm ultraluminous infrared sources at high-z, a class of objects that is rarely found in SMG samples. Indeed SMGs are not common among bright 24 μm sources (e.g., only about 20% of SMGs have f 24μm > 0.4 mJy). Our sample is the largest Spitzer-selected sample

  8. E+A Galaxies: Did They Lose The A to Become E?

    de Rijcke, Sven; Michielsen, D.; Buyle, P.; Pisano, D. J.; Dejonghe, H.; Freeman, K.

    2007-05-01

    Over the last 5 Gyr, the cluster galaxy population has changed dramatically. Whereas clusters at z˜0.5 contain a significant fraction of distorted blue galaxies, this population is almost missing in local clusters. About 60% of these blue galaxies, called E+A galaxies, are characterised by strong Balmer lines, typical for a very young stellar population, but have weak, if any, emission lines, suggesting the absence of star formation (Dressler 1999). It has been suggested that E+As are witnessing the aftermath of a merger-triggered starburst and, over time, evolve into early-type galaxies (Poggianti 1999, Bekki 2005). This would make E+As the crucial link between starbursting merger remnants and quiescent early-types, providing a direct observational window on the formation of massive galaxies. We are conducting HI observations of a sample of 20 E+A galaxies with the Arecibo and Parkes radio telescopes (Buyle 2006). Of the 9 E+As observed so far, 7 have been detected at 21cm, containing significant amounts (˜109 solar masses) of neutral hydrogen. These findings have important implications for the classification of E+As as post-starburst systems and as the progenitors of early-type galaxies. With gas, the raw material for forming stars, still present, E+As may undergo future star-formation episodes, making the link between E+As and early-types less direct than previously thought. This also opens up the possibility that E+As are actively forming stars but that dust, which is surely present, obscures star-forming regions. Moreover, these results raise the question of why the starburst ended, if it did, before consuming all the gas. Possibly, the starburst evaporates the dense molecular clouds, temporarily halting star formation. We present observations of our E+A sample with the MOPRA telescope of HCN, a tracer of the dense molecular ISM, and CO, a tracer of the diffuse molecular ISM, to shed light on this issue. In short, with this multiwavelength data set, we can

  9. The Dust Content and Opacity of Actively Star-Forming Galaxies

    Calzetti, Daniela; Armus, Lee; Bohlin, Ralph C.; Kinney, Anne L.; Koornneef, Jan; Storchi-Bergmann, Thaisa

    2000-01-01

    We present far-infrared (FIR) photometry at 150 and 205 micron(s) of eight low-redshift starburst galaxies obtained with the Infrared Space Observatory (ISO) ISOPHOT. Five of the eight galaxies are detected in both wave bands, and these data are used, in conjunction with IRAS archival photometry, to model the dust emission at lambda approximately greater than 40 microns. The FIR spectral energy distributions (SEDs) are best fitted by a combination of two modified Planck functions, with T approx. 40 - 55 K (warm dust) and T approx. 20-23 K (cool dust) and with a dust emissivity index epsilon = 2. The cool dust can be a major contributor to the FIR emission of starburst galaxies, representing up to 60% of the total flux. This component is heated not only by the general interstellar radiation field, but also by the starburst itself. The cool dust mass is up to approx. 150 times larger than the warm dust mass, bringing the gas-to-dust ratios of the starbursts in our sample close to Milky Way values, once resealed for the appropriate metallicity. The ratio between the total dust FIR emission in the range 1-1000 microns and the IRAS FIR emission in the range 40 - 120 microns is approx. 1.75, with small variations from galaxy to galaxy. This ratio is about 40% larger than previously inferred from data at millimeter wavelengths. Although the galaxies in our sample are generally classified as "UV bright," for four of them the UV energy emerging shortward of 0.2 microns is less than 15% of the FIR energy. On average, about 30% of the bolometric flux is coming out in the UV-to-near-IR wavelength range; the rest is emitted in the FIR. Energy balance calculations show that the FIR emission predicted by the dust reddening of the UV-to-near-IR stellar emission is within a factor of approx. 2 of the observed value in individual galaxies and within 20% when averaged over a large sample. If our sample of local starbursts is representative of high-redshift (z approx. greater than 1

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

    Imanishi, Masatoshi [Subaru Telescope, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Nakanishi, Kouichiro, E-mail: masa.imanishi@nao.ac.jp [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2014-07-01

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

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

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

  12. THE ROLE OF MERGERS IN EARLY-TYPE GALAXY EVOLUTION AND BLACK HOLE GROWTH

    Models of galaxy formation invoke the major merger of gas-rich progenitor galaxies as the trigger for significant phases of black hole growth and the associated feedback that suppresses star formation to create red spheroidal remnants. However, the observational evidence for the connection between mergers and active galactic nucleus (AGN) phases is not clear. We analyze a sample of low-mass early-type galaxies known to be in the process of migrating from the blue cloud to the red sequence via an AGN phase in the green valley. Using deeper imaging from Sloan Digital Sky Survey Stripe 82, we show that the fraction of objects with major morphological disturbances is high during the early starburst phase, but declines rapidly to the background level seen in quiescent early-type galaxies by the time of substantial AGN radiation several hundred Myr after the starburst. This observation empirically links the AGN activity in low-redshift early-type galaxies to a significant merger event in the recent past. The large time delay between the merger-driven starburst and the peak of AGN activity allows for the merger features to decay to the background and hence may explain the weak link between merger features and AGN activity in the literature.

  13. EXPLORING THE z = 3-4 MASSIVE GALAXY POPULATION WITH ZFOURGE: THE PREVALENCE OF DUSTY AND QUIESCENT GALAXIES

    Spitler, Lee R.; Rees, Glen [Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia); Straatman, Caroline M. S.; Labbé, Ivo [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Glazebrook, Karl; Kacprzak, Glenn G.; Nanayakkara, Themiya [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia); Tran, Kim-Vy H.; Papovich, Casey; Kawinwanichakij, Lalitwadee; Mehrtens, Nicola; Tilvi, Vithal; Tomczak, Adam R. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Quadri, Ryan F.; Persson, S. Eric; Kelson, Daniel D.; McCarthy, Patrick J.; Monson, Andrew J. [Carnegie Observatories, Pasadena, CA 91101 (United States); Van Dokkum, Pieter [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Allen, Rebecca, E-mail: lee.spitler@mq.edu.au [Australian Astronomical Observatory, P.O. Box 296 Epping, NSW 1710 (Australia)

    2014-06-01

    Our understanding of the redshift z > 3 galaxy population relies largely on samples selected using the popular ''dropout'' technique, typically consisting of UV-bright galaxies with blue colors and prominent Lyman breaks. As it is currently unknown if these galaxies are representative of the massive galaxy population, we here use the FOURSTAR Galaxy Evolution (ZFOURGE) survey to create a stellar mass-limited sample at z = 3-4. Uniquely, ZFOURGE uses deep near-infrared medium-bandwidth filters to derive accurate photometric redshifts and stellar population properties. The mass-complete sample consists of 57 galaxies with log M >10.6, reaching below M {sup *} at z = 3-4. On average, the massive z = 3-4 galaxies are extremely faint in the observed optical with median R{sub tot}{sup AB}=27.48±0.41 (rest-frame M {sub 1700} = –18.05 ± 0.37). They lie far below the UV luminosity-stellar mass relation for Lyman break galaxies and are about ∼100 × fainter at the same mass. The massive galaxies are red (R – K {sub s} {sub AB} = 3.9 ± 0.2; rest-frame UV-slope β = –0.2 ± 0.3) likely from dust or old stellar ages. We classify the galaxy spectral energy distributions by their rest-frame U–V and V–J colors and find a diverse population: 46{sub −6−17}{sup +6+10}% of the massive galaxies are quiescent, 40{sub −6−5}{sup +6+7}% are dusty star-forming galaxies, and only 14{sub −3−4}{sup +3+10}% resemble luminous blue star-forming Lyman break galaxies. This study clearly demonstrates an inherent diversity among massive galaxies at higher redshift than previously known. Furthermore, we uncover a reservoir of dusty star-forming galaxies with 4 × lower specific star-formation rates compared to submillimeter-selected starbursts at z > 3. With 5 × higher numbers, the dusty galaxies may represent a more typical mode of star formation compared to submillimeter-bright starbursts.

  14. EXPLORING THE z = 3-4 MASSIVE GALAXY POPULATION WITH ZFOURGE: THE PREVALENCE OF DUSTY AND QUIESCENT GALAXIES

    Our understanding of the redshift z > 3 galaxy population relies largely on samples selected using the popular ''dropout'' technique, typically consisting of UV-bright galaxies with blue colors and prominent Lyman breaks. As it is currently unknown if these galaxies are representative of the massive galaxy population, we here use the FOURSTAR Galaxy Evolution (ZFOURGE) survey to create a stellar mass-limited sample at z = 3-4. Uniquely, ZFOURGE uses deep near-infrared medium-bandwidth filters to derive accurate photometric redshifts and stellar population properties. The mass-complete sample consists of 57 galaxies with log M >10.6, reaching below M * at z = 3-4. On average, the massive z = 3-4 galaxies are extremely faint in the observed optical with median RtotAB=27.48±0.41 (rest-frame M 1700 = –18.05 ± 0.37). They lie far below the UV luminosity-stellar mass relation for Lyman break galaxies and are about ∼100 × fainter at the same mass. The massive galaxies are red (R – K s AB = 3.9 ± 0.2; rest-frame UV-slope β = –0.2 ± 0.3) likely from dust or old stellar ages. We classify the galaxy spectral energy distributions by their rest-frame U–V and V–J colors and find a diverse population: 46−6−17+6+10% of the massive galaxies are quiescent, 40−6−5+6+7% are dusty star-forming galaxies, and only 14−3−4+3+10% resemble luminous blue star-forming Lyman break galaxies. This study clearly demonstrates an inherent diversity among massive galaxies at higher redshift than previously known. Furthermore, we uncover a reservoir of dusty star-forming galaxies with 4 × lower specific star-formation rates compared to submillimeter-selected starbursts at z > 3. With 5 × higher numbers, the dusty galaxies may represent a more typical mode of star formation compared to submillimeter-bright starbursts

  15. Observed and predicted Ly-alpha and UV lines for a sample of galaxies at redshifts z<3.7

    Contini, M

    2015-01-01

    We explore the origin of the observed Lya and other UV lines from galaxies at z1000 km/s) component of the emitting gas is accompanied by relatively low preshock densities (n0 ~100-400 cm^-3) leading in some cases to broad forbidden lines. Some spectra are best reproduced by shock dominated models in which the photoionizing source is hidden or absent. Within more than 50 galaxies modelled in this work, only a few spectra from galaxies at z~2.5 correspond to a starburst temperature Ts>10^5 K, similar to that found in galaxies showing some activity.

  16. DISTRIBUTION AND MOTIONS OF H-I AND H-2 IN THE PECULIAR SPIRAL GALAXY NGC-3310

    MULDER, PS; VANDRIEL, W; BRAINE, J

    1995-01-01

    The peculiar Sbc-type starburst galaxy NGC 3310 was mapped in the 21 cm H I line at Westerbork with an angular resolution of 12''.2 x 15''.1 (alpha x delta) and a velocity resolution of 33 km s(-1). The galaxy was also partially mapped in the CO(1-0) and (2-1) lines at IRAM with resolutions of simil

  17. Correlation between Post-LASIK Starburst Symptom and Ocular Wavefront Aberrations

    LIU Yong-Ji; MU Guo-Guang; WANG Zhao-Qi; WANG Yan

    2006-01-01

    Monochromatic aberrations in post laser in-situ keratomileusis (LASIK) eyes are measured. The data are categorized into reference group and starburst group according to the visual symptoms. Statistic analysis has been made to find the correJation between the ocular wavefront aberrations and the starburst symptom. The rms aberrations of the 3rd and 4th orders for the starburst group are significantly larger than those for the reference group. The starburst symptom shows a strong correlation with vertical coma, total coma, spherical aberrations. For 3-mm pupil size and 5.8-mm pupil size, the modulation transfer function (MTF) of the starburst group are lower than those of the reference group, but their visual acuities are close. MTF and PSF analyses are made for two groups, and the results are consistent with the statistical analysis, which means the difference between the two groups is mainly due to the third- and fourth-order Zernike aberrations.

  18. Star Formation in Tadpole Galaxies

    Munoz-Tunon, Casiana; Elmegreen, Debra M; Elmegreen, Bruce G

    2014-01-01

    Tadpole Galaxies look like a star forming head with a tail structure to the side. They are also named cometaries. In a series of recent works we have discovered a number of issues that lead us to consider them extremely interesting targets. First, from images, they are disks with a lopsided starburst. This result is firmly established with long slit spectroscopy in a nearby representative sample. They rotate with the head following the rotation pattern but displaced from the rotation center. Moreover, in a search for extremely metal poor (XMP) galaxies, we identified tadpoles as the dominant shapes in the sample- nearly 80% of the local XMP galaxies have a tadpole morphology. In addition, the spatially resolved analysis of the metallicity shows the remarkable result that there is a metallicity drop right at the position of the head. This is contrary to what intuition would say and difficult to explain if star formation has happened from gas processed in the disk. The result could however be understood if the ...

  19. Infrared Narrowband Tomography of the Local Starburst NGC 1569 with the Large Binocular Telescope/LUCIFER

    Pasquali, A.; Bik, A.; Zibetti, S.; Ageorges, N.; Seifert, W.; Brandner, W.; Rix, H.-W.; Jütte, M.; Knierim, V.; Buschkamp, P.; Feiz, C.; Gemperlein, H.; Germeroth, A.; Hofmann, R.; Laun, W.; Lederer, R.; Lehmitz, M.; Lenzen, R.; Mall, U.; Mandel, H.; Müller, P.; Naranjo, V.; Polsterer, K.; Quirrenbach, A.; Schäffner, L.; Storz, C.; Weiser, P.

    2011-04-01

    We used the near-IR imager/spectrograph LUCIFER mounted on the Large Binocular Telescope to image, with subarcsecond seeing, the local dwarf starburst NGC 1569 in the JHK bands and He I 1.08 μm, [Fe II] 1.64 μm, and Brγ narrowband filters. We obtained high-quality spatial maps of He I 1.08 μm, [Fe II] 1.64 μm, and Brγ emission across the galaxy, and used them together with Hubble Space Telescope/Advanced Camera for Surveys images of NGC 1569 in the Hα filter to derive the two-dimensional spatial map of the dust extinction and surface star formation rate (SFR) density. We show that dust extinction (as derived from the Hα/Brγ flux ratio) is rather patchy and, on average, higher in the northwest (NW) portion of the galaxy (E g(B - V) ~= 0.71 mag) than in the southeast (E g(B - V) ~= 0.57 mag). Similarly, the surface density of SFR (computed from either the dereddened Hα or dereddened Brγ image) peaks in the NW region of NGC 1569, reaching a value of about 4 × 10-6 M sun yr-1 pc-2. The total SFR as estimated from the integrated, dereddened Hα (or, alternatively, Brγ) luminosity is about 0.4 M sun yr-1, and the total supernova rate from the integrated, dereddened [Fe II] 1.64 μm luminosity is about 0.005 yr-1 (assuming a distance of 3.36 Mpc). The azimuthally averaged [Fe II] 1.64 μm/Brγ flux ratio is larger at the edges of the central, gas-deficient cavities (encompassing the superstar clusters A and B) and in the galaxy outskirts. If we interpret this line ratio as the ratio between the average past star formation (as traced by supernovae) and ongoing activity (represented by OB stars able to ionize the interstellar medium), it would then indicate that star formation has been quenched within the central cavities and lately triggered in a ring around them. The number of ionizing hydrogen and helium photons as computed from the integrated, dereddened Hα and He I 1.08 μm luminosities suggests that the latest burst of star formation occurred about 4 Myr

  20. INFRARED NARROWBAND TOMOGRAPHY OF THE LOCAL STARBURST NGC 1569 WITH THE LARGE BINOCULAR TELESCOPE/LUCIFER

    We used the near-IR imager/spectrograph LUCIFER mounted on the Large Binocular Telescope to image, with subarcsecond seeing, the local dwarf starburst NGC 1569 in the JHK bands and He I 1.08 μm, [Fe II] 1.64 μm, and Brγ narrowband filters. We obtained high-quality spatial maps of He I 1.08 μm, [Fe II] 1.64 μm, and Brγ emission across the galaxy, and used them together with Hubble Space Telescope/Advanced Camera for Surveys images of NGC 1569 in the Hα filter to derive the two-dimensional spatial map of the dust extinction and surface star formation rate (SFR) density. We show that dust extinction (as derived from the Hα/Brγ flux ratio) is rather patchy and, on average, higher in the northwest (NW) portion of the galaxy (Eg(B - V) ≅ 0.71 mag) than in the southeast (Eg(B - V) ≅ 0.57 mag). Similarly, the surface density of SFR (computed from either the dereddened Hα or dereddened Brγ image) peaks in the NW region of NGC 1569, reaching a value of about 4 x 10-6 Msun yr-1 pc-2. The total SFR as estimated from the integrated, dereddened Hα (or, alternatively, Brγ) luminosity is about 0.4 Msun yr-1, and the total supernova rate from the integrated, dereddened [Fe II] 1.64 μm luminosity is about 0.005 yr-1 (assuming a distance of 3.36 Mpc). The azimuthally averaged [Fe II] 1.64 μm/Brγ flux ratio is larger at the edges of the central, gas-deficient cavities (encompassing the superstar clusters A and B) and in the galaxy outskirts. If we interpret this line ratio as the ratio between the average past star formation (as traced by supernovae) and ongoing activity (represented by OB stars able to ionize the interstellar medium), it would then indicate that star formation has been quenched within the central cavities and lately triggered in a ring around them. The number of ionizing hydrogen and helium photons as computed from the integrated, dereddened Hα and He I 1.08 μm luminosities suggests that the latest burst of star formation occurred about 4 Myr

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

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

    1997-01-01

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

  2. The Connection among Gamma-ray Burst Host-Galaxies, BL Lacs and Quasars

    Rej, A.

    1999-01-01

    A possible connection among host-galaxies of gamma-ray bursts, BL Lacs and quasars is analysed. It is believed that the gamma-ray bursts, which do not show radio or infrared emission, occur in faint blue dwarf galaxies, that are seen around radio-quiet quasars, which lie in clusters. The GRB counterparts, which show radio emission, may be associated with more evolved starbursting environments, and arise from red galaxies, that are observed around some radio-loud quasars lying in richer cluste...

  3. Radiation Pressure Supported Starburst Disks and AGN Fueling

    Thompson, T A; Murray, N; Thompson, Todd A.; Quataert, Eliot; Murray, Norm

    2005-01-01

    We consider the structure of marginally Toomre-stable starburst disks under the assumption that radiation pressure on dust grains provides the dominant vertical support against gravity. This is particularly appropriate when the disk is optically thick to its own IR radiation, as in the central regions of ULIRGs. Because the disk radiates at its Eddington limit, the Schmidt-law for star formation changes in the optically-thick limit, with the star formation rate per unit area scaling as Sigma_g/kappa, where Sigma_g is the gas surface density and kappa is the mean opacity. We show that optically thick starburst disks have a characteristic flux and dust effective temperature of F10^{13} L_sun/kpc^2 and T_eff~90K, respectively. We compare our predictions with observations and find good agreement. We extend our model from many-hundred parsec scales to sub-parsec scales and address the problem of fueling AGN. We assume that angular momentum transport proceeds via global torques rather than a local viscosity. We acc...

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

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

    2012-01-01

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

  5. Extragalactic background light inferred from AEGIS galaxy SED-type fractions

    Dominguez, A; Rosario, D J; Prada, F; Gilmore, R C; Faber, S M; Koo, D C; Somerville, R S; Perez-Torres, M A; Perez-Gonzalez, P; Huang, J -S; Davis, M; Guhathakurta, P; Barmby, P; Conselice, C J; Lozano, M; Newman, J A; Cooper, M C

    2011-01-01

    The extragalactic background light (EBL) is of fundamental importance both for understanding the entire process of galaxy evolution and for gamma-ray astronomy. However, the overall spectrum of the EBL between 0.1 and 1000 microns has never been determined directly neither from observed luminosity functions (LFs), over a wide redshift range, nor from any multiwavelength observation of galaxy spectral energy distributions (SEDs). The evolving, overall spectrum of the EBL is derived here utilizing a novel method based on observations only. The changing fractions of quiescent galaxies, star-forming galaxies, starburst galaxies and active galactic nucleus (AGN) galaxies from redshift 0.2 to 1 are estimated, and two alternative extrapolations of SED types to higher redshifts are considered. This allows calculation of the evolving EBL. The EBL uncertainties in our modelling based directly on the data are quantified, and their consequences for attenuation of very-high-energy gamma-rays due to pair production on the ...

  6. Unveiling the Nature of the "Green Pea" Galaxies: Oxygen and Nitrogen Chemical Abundances

    Amorín, R. O.; Pérez-Montero, E.; Vílchez, J. M.

    2011-07-01

    We present recent results on the oxygen and nitrogen chemical abundances in the extremely compact, low-mass starburst galaxies at redshifts 0.1-0.3 usually referred to as "green pea" galaxies. We show that they are metal-poor galaxies (~1/5 solar) with lower oxygen abundances than star-forming galaxies of similar mass and N/O ratios unusually high for galaxies of the same metallicity. Recent, rapid, and massive inflows of cold gas, possibly coupled with enriched outflows from supernova winds, are used to explain the results. This is consistent with the known "pea" galaxy properties and suggest that these rare objects are experiencing a short and extreme phase in their evolution.

  7. High-energy emission from star-forming galaxies

    Persic, Massimo

    2011-01-01

    Adopting the convection-diffusion model for energetic electron and proton propagation, and accounting for all the relevant hadronic and leptonic processes, the steady-state energy distributions of these particles in the starburst galaxies M82 and NGC253 can be determined with a detailed numerical treatment. The electron distribution is directly normalized by the measured synchrotron radio emission from the central starburst region; a commonly expected theoretical relation is then used to normalize the proton spectrum in this region, and a radial profile is assumed for the magnetic field. The resulting radiative yields of electrons and protons are calculated: the predicted >100MeV and >100GeV fluxes are in agreement with the corresponding quantities measured with the orbiting Fermi telescope and the ground-based VERITAS and HESS Cherenkov telescopes. The cosmic-ray energy densities in central regions of starburst galaxies, as inferred from the radio and gamma-ray measurements of (respectively) non-thermal sync...

  8. Galaxy formation in pre-processed dark halos

    Mo, H J; Mao, Shude

    2003-01-01

    Recent N-body simulations show that the formation of a present-day, galaxy sized dark matter halo in the CDM cosmogony in general consists of an early fast collapse phase, during which the potential associated with a halo is established, followed by a slow accretion phase, during which mass is added rather gently in the outer region. Here we outline a scenario in which the fast collapse phase is accompanied with rapid formation of cold clouds and with starbursts that can eject a large amount of gas from the halo center.The loss of orbital energy of the cold clouds to the dark matter and the ejection of gas from halo center by starburst can significantly reduce the halo concentration. The outflow from the starburst can also heat the gas in the protogalaxy region. Subsequent formation of galaxies in the slow accretion regime is therefore in halos that have been pre-processed by these processes and may have properties different from that given by N-body simulations. This scenario can help to solve several outsta...

  9. The molecular astrophysics of stars and galaxies.

    Hartquist, T. W.; Williams, D. A.

    This book provides a comprehensive survey of modern molecular astrophysics. It gives an introduction to molecular spectroscopy and then addresses the main areas of current molecular astrophysics, including galaxy formation, star forming regions, mass loss from young as well as highly evolved stars and supernovae, starburst galaxies plus the tori and discs near the central engines of active galactic nuclei. With chapters written by leading experts, the book is unique in giving a detailed view of this wide-ranging subject. It will provide the standard introduction for research students in molecular astrophysics; it will also enable chemists to learn the astrophysics most related to chemistry as well as instruct physicists about the molecular processes most important in astronomy. This volume is dedicated to Alexander Dalgarno.

  10. Galaxy Formation

    Sparre, Martin

    Galaxy formation is an enormously complex discipline due to the many physical processes that play a role in shaping galaxies. The objective of this thesis is to study galaxy formation with two different approaches: First, numerical simulations are used to study the structure of dark matter and how...... galaxies form stars throughout the history of the Universe, and secondly it is shown that observations of gamma-ray bursts (GRBs) can be used to probe galaxies with active star formation in the early Universe. A conclusion from the hydrodynamical simulations is that the galaxies from the stateof...... important, since it helps constraining chemical evolution models at high redshift. A new project studying how the population of galaxies hosting GRBs relate to other galaxy population is outlined in the conclusion of this thesis. The core of this project will be to quantify how the stellar mass function of...

  11. Active Galaxies

    Kilerci Eser, Ece

    Galaxy formation and evolution is one of the main research themes of modern astronomy. Active galaxies such as Active Galactic Nuclei (AGN) and Ultraluminous Infrared Galaxies (ULIRGs) are important evolutionary stages of galaxies. The ULIRG stage is mostly associated with galaxy mergers and...... interactions. During the interactions of gas-rich galaxies, the gas inflows towards the centers of the galaxies and can trigger both star formation and AGN activity. The ULIRG stage includes rapid star formation activity and fast black hole growth that is enshrouded by dust. Once the AGN emission is...... one is related to the mass estimates of supermassive black holes (SMBHs). Mass estimates of SMBHs are important to understand the formation and evolution of SMBHs and their host galaxies. Black hole masses in Type 1 AGN are measured with the reverberation mapping (RM) technique. Reverberation mapping...

  12. Oxygen, Carbon and Nitrogen evolution in galaxies

    Chiappini, C; Matteucci, F; Chiappini, Cristina; Romano, Donatella; Matteucci, Francesca

    2003-01-01

    We discuss the evolution of oxygen, carbon and nitrogen in galaxies of different morphological type by adopting detailed chemical evolution models with different star formation histories (continuous star formation or starbursts). We start by computing chemical evolution models for the Milky Way with different stellar nucleosynthesis prescriptions. Then, a comparison between model results and ``key'' observational constraints allows us to choose the best set of stellar yields. Once the best set of yields is identified for the Milky Way, we apply the same nucleosynthesis prescriptions to other spirals (in particular M101) and dwarf irregular galaxies. We compare our model predictions with the [C,N,O/Fe] vs. [Fe/H], log(C/O) vs. 12+ log(O/H), log(N/O) vs. 12+ log(O/H) and [C/O] vs. [Fe/H] relations observed in the solar vicinity, along the disk and in other galaxies. By taking into account the results obtained for all the studied galaxies (Milky Way, M101, dwarf galaxies and DLAs) our main conclusions are: a) on...

  13. Galaxy Formation at z~3 Constraints from Spatial Clustering

    Wechsler, R H; Bullock, J S; Kolatt, T S; Primack, Joel R; Blumenthal, G R; Dekel, A; Wechsler, Risa H.; Somerville, Rachel S.; Bullock, James S.; Kolatt, Tsafrir S.; Primack, Joel R.; Blumenthal, George R.; Dekel, Avishai

    2001-01-01

    We use N-body simulations combined with semi-analytic models to compute the clustering properties of modeled galaxies at z~3, and confront these predictions with the clustering properties of the observed population of Lyman-break galaxies (LBGs). Several scenarios for the nature of LBGs are explored, which may be broadly categorized into models in which high-redshift star formation is driven by collisional starbursts and those in which quiescent star formation dominates. For each model, we make predictions for the LBG overdensity distribution, the variance of counts-in-cells, the correlation length, and close pair statistics. Models which assume a one-to-one relationship between massive dark-matter halos and galaxies are disfavored by close pair statistics, as are models in which colliding halos are associated with galaxies in a simplified way. However, when modeling of gas consumption and star formation is included using a semi-analytic treatment, the quiescent and collisional starburst models predict simila...

  14. METALS REMOVED BY OUTFLOWS FROM MILKY WAY DWARF SPHEROIDAL GALAXIES

    The stars in the dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are significantly more metal-poor than would be expected from a closed box model of chemical evolution. Gas outflows likely carried away most of the metals produced by the dSphs. Based on previous Keck/DEIMOS observations and models, we calculate the mass in Mg, Si, Ca, and Fe expelled from each of eight dSphs. Essentially, these masses are the differences between the observed amount of metals present in the dSphs' stars today and the inferred amount of metals produced by supernovae. We conclude that the dSphs lost 96% to >99% of the metals their stars manufactured. We apply the observed mass function of Milky Way dSphs to the ejected mass function to determine that a single large dSph, like Fornax, lost more metals over 10 Gyr than all smaller dSphs combined. Therefore, small galaxies like dSphs are not significant contributors to the metal content of the intergalactic medium. Finally, we compare our ejected mass function to previous X-ray measurements of the metal content of the winds from the post-starburst dwarf irregular galaxy NGC 1569. Remarkably, the most recent starburst in that galaxy falls exactly on the ejected-mass-stellar-mass relation defined by the Milky Way dSphs.

  15. A unified multi-wavelength model of galaxy formation

    Lacey, Cedric G; Frenk, Carlos S; Benson, Andrew J; Bower, Richard G; Cole, Shaun; Gonzalez-Perez, Violeta; Helly, John C; Lagos, Claudia D P; Mitchell, Peter D

    2015-01-01

    We present a new version of the GALFORM semi-analytical model of galaxy formation. This brings together several previous developments of GALFORM into a single unified model, including a different initial mass function (IMF) in quiescent star formation and in starbursts, feedback from active galactic nuclei supressing gas cooling in massive halos, and a new empirical star formation law in galaxy disks based on their molecular gas content. In addition, we have updated the cosmology, introduced a more accurate treatment of dynamical friction acting on satellite galaxies, and updated the stellar population model. The new model is able to simultaneously explain both the observed evolution of the K-band luminosity function and stellar mass function, and the number counts and redshift distribution of sub-mm galaxies selected at 850 mu. This was not previously achieved by a single physical model within the LambdaCDM framework, but requires having an IMF in starbursts that is somewhat top-heavy. The new model is teste...

  16. Evidence for outflows in z ~ 6 galaxies with ALMA

    Gallerani, S; Feruglio, C; Ferrara, A; Maiolino, R; Vallini, L; Riechers, D A

    2016-01-01

    We present the first attempt to detect outflows from galaxies approaching the Epoch of Reionization (EoR) using a sample of 9 star-forming (5 < SFR < 70 Msun/yr) z ~ 6 galaxies for which high-quality spectra of the [CII]158 micron line has been previously obtained with ALMA. We first fit each line with a Gaussian function and compute the residuals by subtracting the best fitting model from the data. We combine the residuals of all sample galaxies and find that the total signal is characterized by a flux excess that can be ascribed to broad wings of the [CII] line, which we interpret as a signature of starburst-driven outflows. The tentatively inferred outflow rate is dM/dt ~ 65 Msun/yr. Our interpretation is consistent with results from zoomed hydro- simulations of Dahlia, a z ~ 7 galaxy (SFR ~ 100 Msun/yr) whose feedback-regulated star formation results in an outflow rate dM/dt ~ 30 Msun/yr. These results suggest that starburst-driven outflows are in place in the EoR. Deeper observations of the [CII] l...

  17. GeV Observations of Star-forming Galaxies with \\textit{Fermi} LAT

    Ackermann, M; Allafort, A; Baldini, L; Ballet, J; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Cillis, A N; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cutini, S; De Palma, F; Dermer, C D; Digel, S W; Silva, E Do Couto e; Drell, P S; Drlica-Wagner, A; Favuzzi, C; Fegan, S J; Fortin, P; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Germani, S; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Guiriec, S; Gustafsson, M; Hadasch, D; Hayashida, M; Hays, E; Hughes, R E; Jóhannesson, G; Johnson, A S; Kamae, T; Katagiri, H; Kataoka, J; Knödlseder, J; Kuss, M; Lande, J; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Martin, P; Mazziotta, M N; McEnery, J E; Michelson, P F; Mizuno, T; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nishino, S; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ozaki, M; Parent, D; Persic, M; Pesce-Rollins, M; Petrosian, V; Pierbattista, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Ritz, S; Roth, M; Sbarra, C; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Stawarz, \\{L}ukasz; Strong, A W; Takahashi, H; Tanaka, T; Thayer, J B; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Vandenbroucke, J; Vianello, G; Vitale, V; Waite, A P; Wood, M; Yang, Z

    2012-01-01

    Recent detections of the starburst galaxies M82 and NGC 253 by gamma-ray telescopes suggest that galaxies rapidly forming massive stars are more luminous at gamma-ray energies compared to their quiescent relatives. Building upon those results, we examine a sample of 69 dwarf, spiral, and luminous and ultraluminous infrared galaxies at photon energies 0.1-100 GeV using 3 years of data collected by the Large Area Telescope (LAT) on the \\textit{Fermi Gamma-ray Space Telescope} (\\textit{Fermi}). Measured fluxes from significantly detected sources and flux upper limits for the remaining galaxies are used to explore the physics of cosmic rays in galaxies. We find further evidence for quasi-linear scaling relations between gamma-ray luminosity and both radio continuum luminosity and total infrared luminosity which apply both to quiescent galaxies of the Local Group and low-redshift starburst galaxies (conservative $P$-values $\\lesssim0.05$ accounting for statistical and systematic uncertainties). The normalizations ...

  18. [CII] line emission in massive star-forming galaxies at z=4.7

    Wagg, J; Carilli, C L; Espada, D; Peck, A; Riechers, D; Walter, F; Wootten, A; Aravena, M; Barkats, D; Cortes, J R; Hills, R; Hodge, J; Impellizzeri, C M V; Iono, D; Leroy, A; Martin, S; Rawlings, M G; Maiolino, R; McMahon, R G; Scott, K S; Villard, E; Vlahakis, C

    2012-01-01

    We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [CII] 157.7micron fine structure line and thermal dust continuum emission from a pair of gas-rich galaxies at z=4.7, BR1202-0725. This system consists of a luminous quasar host galaxy and a bright submm galaxy (SMG), while a fainter star-forming galaxy is also spatially coincident within a 4'' (25 kpc) region. All three galaxies are detected in the submm continuum, indicating FIR luminosities in excess of 10^13 Lsun for the two most luminous objects. The SMG and the quasar host galaxy are both detected in [CII] line emission with luminosities, L([CII]) = (10.0 +/- 1.5)x10^9 Lsun and L([CII]) = (6.5+/-1.0)x10^9 Lsun, respectively. We estimate a luminosity ratio, L([CII])/L(FIR) = (8.3+/-1.2)x10^-4 for the starburst SMG to the North, and L([CII])/L(FIR) = (2.5+/-0.4)x10^-4 for the quasar host galaxy, in agreement with previous high-redshift studies that suggest lower [CII]-to-FIR luminosity ratios in quasars than in starburst gal...

  19. Spectroscopy of Luminous Compact Blue Galaxies in Distant Clusters II. Physical Properties of dE Progenitor Candidates

    Crawford, S M; Bershady, M A; Randriamampandry, S M

    2015-01-01

    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 >10^15 M_sun), 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 clust...

  20. A far-IR view of the starburst-driven superwind in NGC 2146

    Kreckel, K.; Groves, B.; Lyubenova, M.; Schinnerer, E.; Meidt, S. [Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Armus, L.; Díaz-Santos, T. [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States); Appleton, P. [NASA Herschel Science Center, IPAC, California Institute of Technology, Pasadena, CA 91125 (United States); Croxall, K. V. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Dale, D. A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Hunt, L. K. [INAF-Osservatorio Astrosico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Beirão, P. [Observatoire de Paris, 61 avenue de l' Observatoire, F-75014 Paris (France); Bolatto, A. D. [Department of Astronomy and Joint Space-Science Institute, University of Maryland, College Park, MD (United States); Calzetti, D. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Donovan Meyer, J. [National Radio Astronomy Observatory, Charlottesville, VA 22901 (United States); Draine, B. T. [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001 (United States); Hinz, J. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Kennicutt, R. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Murphy, E. J. [Infrared Processing and Analysis Center, California Institute of Technology, MC 220-6, Pasadena, CA 91125 (United States); Smith, J. D. T., E-mail: kreckel@mpia.de [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); and others

    2014-07-20

    NGC 2146, a nearby luminous infrared galaxy, presents evidence for outflows along the disk minor axis in all gas phases (ionized, neutral atomic, and molecular). We present an analysis of the multi-phase, starburst-driven superwind in the central 5 kpc as traced in spatially resolved spectral line observations, using far-IR Herschel PACS spectroscopy, to probe the effects on the atomic and ionized gas, and optical integral field spectroscopy to examine the ionized gas through diagnostic line ratios. We observe an increased ∼250 km s{sup –1} velocity dispersion in the [O I] 63 μm, [O III] 88 μm, [N II] 122 μm, and [C II] 158 μm fine-structure lines that is spatially coincident with high excitation gas above and below the disk. We model this with a slow ∼200 km s{sup –1} shock and trace the superwind to the edge of our field of view 2.5 kpc above the disk. We present new SOFIA 37 μm observations to explore the warm dust distribution, and detect no clear dust entrainment in the outflow. The stellar kinematics appear decoupled from the regular disk rotation seen in all gas phases, consistent with a recent merger event disrupting the system. We consider the role of the superwind in the evolution of NGC 2146 and speculate on the evolutionary future of the system. Our observations of NGC 2146 in the far-IR allow an unobscured view of the wind, crucial for tracing the superwind to the launching region at the disk center, and provide a local analog for future ALMA observations of outflows in high-redshift systems.

  1. A far-IR view of the starburst-driven superwind in NGC 2146

    NGC 2146, a nearby luminous infrared galaxy, presents evidence for outflows along the disk minor axis in all gas phases (ionized, neutral atomic, and molecular). We present an analysis of the multi-phase, starburst-driven superwind in the central 5 kpc as traced in spatially resolved spectral line observations, using far-IR Herschel PACS spectroscopy, to probe the effects on the atomic and ionized gas, and optical integral field spectroscopy to examine the ionized gas through diagnostic line ratios. We observe an increased ∼250 km s–1 velocity dispersion in the [O I] 63 μm, [O III] 88 μm, [N II] 122 μm, and [C II] 158 μm fine-structure lines that is spatially coincident with high excitation gas above and below the disk. We model this with a slow ∼200 km s–1 shock and trace the superwind to the edge of our field of view 2.5 kpc above the disk. We present new SOFIA 37 μm observations to explore the warm dust distribution, and detect no clear dust entrainment in the outflow. The stellar kinematics appear decoupled from the regular disk rotation seen in all gas phases, consistent with a recent merger event disrupting the system. We consider the role of the superwind in the evolution of NGC 2146 and speculate on the evolutionary future of the system. Our observations of NGC 2146 in the far-IR allow an unobscured view of the wind, crucial for tracing the superwind to the launching region at the disk center, and provide a local analog for future ALMA observations of outflows in high-redshift systems.

  2. From nearby low-mass protostars to high redshift starbursts: protostellar outflows tracing the IMF

    Kristensen, Lars E.; Bergin, Edwin

    2015-08-01

    Embedded low-mass protostars are notoriously difficult to observe even in the nearest Galactic high-mass clusters where they outnumber the high-mass protostars by orders of magnitude. Thus, without a good tracer of the low-mass population, we do not have a good handle on the shape of the initial (core) mass function, leaving little hope for extrapolating to extragalactic regions where we will never have neither the sensitivity nor the resolution to directly observe this population. A good tracer of the low-mass population is needed.One such physical tracer is outflows. Outflow emission is directly proportional to envelope mass, and outflows are predominantly active during the deeply embedded phases of star formation. What is required for this method to work is species and transitions tracing outflows uniquely such that any signal is not diluted by the surrounding cloud, such as certain methanol transitions, water, high-J CO (J > 10).I will present a statistical model of a forming high-mass cluster. The model includes what we currently know about Galactic high-mass clusters and incorporates outflow emission from low-mass protostars. The latter component is obtained from observations of tens of nearby embedded low-mass protostellar outflows in the above-mentioned tracers. The model is benchmarked against ALMA and Herschel-HIFI observations of Galactic clusters proving the concept, and preliminary extrapolations to the extragalactic regime are presented. With this new probe, and traditional probes of the distant star formation which predominantly trace high mass stars, we will be able to explore the IMF in starburst galaxies from low to high redshift.

  3. Elliptical Galaxies and Bulges of Disc Galaxies: Summary of Progress and Outstanding Issues

    Kormendy, John

    Bulge components of disc galaxies are the high-density centers interior to their outer discs. Once thought to be equivalent to elliptical galaxies, their observed properties and formation histories turn out to be richer and more varied than those of ellipticals. This book reviews progress in many areas of bulge studies. Two advances deserve emphasis: (1) Observations divide bulges into "classical bulges" that look indistinguishable from ellipticals and "pseudobulges" that are discier and (except in S0s) more actively star-forming than are ellipticals. Classical bulges and ellipticals are thought to form by major galaxy mergers. Discy pseudobulges are a product of the slow ("secular") evolution of galaxy discs. Nonaxisymmetries such as bars and oval distortions transport some disc gas toward the center, where it starbursts and builds a dense central component that is discier in structure than are classical bulges. Secular evolution explains many regular structures (e.g., rings) seen in galaxy discs. It is a new area of galaxy evolution work that complements hierarchical clustering. (2) Studies of high-redshift galaxies reveal that their discs are so gas-rich that they are violently unstable to the formation of mass clumps that sink to the center and merge. This is an alternative channel for the formation of classical bulges. This chapter summarizes big-picture successes and unsolved problems in the formation of bulges and ellipticals and their coevolution (or not) with supermassive black holes. I present an observer's perspective on simulations of cold dark matter galaxy formation including baryonic physics. Our picture of the quenching of star formation is becoming general and secure at redshifts z 1000 in mass but that differ from each other as we observe over that whole range. A related difficulty is how hierarchical clustering makes so many giant, bulgeless galaxies in field but not cluster environments. I present arguments that we rely too much on star

  4. State of the gas in intense lensed starbursts

    George, Richard David

    2015-01-01

    The most intensely star-forming galaxies lie at z ∼ 2 and are thought to be the progenitors of the most massive galaxies today, yet study of this important population has been hampered by vast quantities of dust, making them almost invisible in the optical and ultraviolet (UV) regimes, and by the low sensitivity and angular resolution of many infrared (IR) facilities. Chapter 2 describes the use of the flux and angular extent boost provided by strong gravitational lensing in th...

  5. Secular Evolution in Disk Galaxies

    Kormendy, John

    2013-10-01

    bulges because the latter retain a `memory' of their disky origin. That is, they have one or more characteristics of disks: (1) flatter shapes than those of classical bulges, (2) correspondingly large ratios of ordered to random velocities, (3) small velocity dispersions with respect to the Faber-Jackson correlation between velocity dispersion and bulge luminosity, (4) spiral structure or nuclear bars in the `bulge' part of the light profile, (5) nearly exponential brightness profiles and (6) starbursts. So the cleanest examples of pseudobulges are recognisable. However, pseudo and classical bulges can coexist in the same galaxy. I review two important implications of secular evolution: (1) The existence of pseudobulges highlights a problem with our theory of galaxy formation by hierarchical clustering. We cannot explain galaxies that are completely bulgeless. Galaxy mergers are expected to happen often enough so that every giant galaxy should have a classical bulge. But we observe that bulgeless giant galaxies are common in field environments. We now realise that many dense centres of galaxies that we used to think are bulges were not made by mergers; they were grown out of disks. So the challenge gets more difficult. This is the biggest problem faced by our theory of galaxy formation. (2) Pseudobulges are observed to contain supermassive black holes (BHs), but they do not show the well-known, tight correlations between BH mass and the mass and velocity dispersion of the host bulge. This leads to the suggestion that there are two fundamentally different BH feeding processes. Rapid global inward gas transport in galaxy mergers leads to giant BHs that correlate with host ellipticals and classical bulges, whereas local and more stochastic feeding of small BHs in largely bulgeless galaxies evidently involves too little energy feedback to result in BH-host coevolution. It is an important success of the secular evolution picture that morphological differences can be used to

  6. Evolving Starburst Modeling of FIR/sub-mm/mm Line Emission. II. Application to M 82

    Yao, Lihong

    2009-01-01

    We present starburst models for far-infrared/sub-millimeter/millimeter (FIR/sub-mm/mm) line emission of molecular and atomic gas in an evolving starburst region, which is treated as an ensemble of non-interacting hot bubbles which drive spherical shells of swept-up gas into a surrounding uniform gas medium. These bubbles and shells are driven by stellar winds and supernovae within massive star clusters formed during an instantaneous starburst. The underlying stellar radiation from the evolving clusters affects the properties and structure of photodissociation regions (PDRs) in the shells, and hence the spectral energy distributions (SEDs) of the molecular and atomic line emission from these swept-up shells and the associated parent giant molecular clouds (GMCs) contains a signature of the stage of evolution of the starburst. The physical and chemical properties of the shells and their structure are computed using a a simple well known similarity solution for the shell expansion, a stellar population synthesis...

  7. INSTANTANEOUS STARBURST OF THE MASSIVE CLUSTERS WESTERLUND 1 AND NGC 3603 YC

    Kudryavtseva, Natalia; Brandner, Wolfgang; Gennaro, Mario; Rochau, Boyke; Henning, Thomas [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Stolte, Andrea [Argelander Institut fuer Astronomie, Auf dem Huegel 71, 53121 Bonn (Germany); Andersen, Morten; Da Rio, Nicola [European Space Agency, Space Science Department, Keplerlaan 1, 2200 AG Noordwijk (Netherlands); Tognelli, Emanuele [Department of Physics, University of Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa (Italy); Hogg, David [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, Room 424, New York, NY 10003 (United States); Clark, Simon [Department of Physics and Astronomy, The Open University, Milton Keynes MK7 6AA (United Kingdom); Waters, Rens [Sterrenkundig Instituut Anton Pannekoek, University of Amsterdam, Science Park 904, 1098 Amsterdam (Netherlands)

    2012-05-10

    We present a new method to determine the age spread of resolved stellar populations in a starburst cluster. The method relies on a two-step process. In the first step, kinematic members of the cluster are identified based on multi-epoch astrometric monitoring. In the second step, a Bayesian analysis is carried out, comparing the observed photometric sequence of cluster members with sets of theoretical isochrones. When applying this methodology to optical and near-infrared high angular resolution Hubble Space Telescope (HST) and adaptive optics observations of the {approx}5 Myr old starburst cluster Westerlund 1 and {approx}2 Myr old starburst cluster NGC 3603 YC, we derive upper limits for the age spreads of 0.4 and 0.1 Myr, respectively. The results strongly suggest that star formation in these starburst clusters happened almost instantaneously.

  8. THE RADIO LUMINOSITY FUNCTION AND GALAXY EVOLUTION IN THE COMA CLUSTER

    We investigate the radio luminosity function and radio source population for two fields within the Coma cluster of galaxies, with the fields centered on the cluster core and southwest infall region and each covering about half a square degree. Using VLA data with a typical rms sensitivity of 28 μJy per 4.''4 beam, we identify 249 radio sources with optical counterparts brighter than r = 22. For cluster galaxies, these correspond to L 1.4 = 1.7 x 1020 W Hz-1(for a 5σ source) and Mr = -13. Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between sources powered by an active nucleus and sources powered by active star formation. The radio-detected star-forming galaxies are the dominant population only at radio luminosities between about 1021 and 1022 W Hz-1, an interesting result given star formation dominates field radio luminosity functions for all luminosities lower than about 1023 W Hz-1. The majority of the radio-detected star-forming galaxies have characteristics of starbursts, including high specific star formation rates and optical spectra with strong emission lines. In conjunction with prior studies on post-starburst galaxies within the Coma cluster, this is consistent with a picture in which late-type galaxies entering Coma undergo a starburst prior to a rapid cessation of star formation. Optically bright elliptical galaxies (Mr ≤ -20.5) make the largest contribution to the radio luminosity function at both the high (∼>3x1022 W Hz-1) and low (∼21 W Hz-1) ends. Through a stacking analysis of these optically bright ellipticals we find that they continue to harbor radio sources down to luminosities as faint as 3 x 1019 W Hz-1. However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint (Mr ∼ -14) dwarf ellipticals hosting strong radio AGNs.

  9. The Radio Luminosity Function and Galaxy Evolution in the Coma Cluster

    Miller, Neal A.; Hornschemeier, Ann E.; Mabasher, Bahram; Brudgesm Terrry J.; Hudson, Michael J.; Marzke, Ronald O.; Smith, Russell J.

    2008-01-01

    We investigate the radio luminosity function and radio source population for two fields within the Coma cluster of galaxies, with the fields centered on the cluster core and southwest infall region and each covering about half a square degree. Using VLA data with a typical rms sensitivity of 28 (mu)Jy per 4.4" beam, we identify 249 radio sources with optical counterparts brighter than r = 22 (equivalent to M(sub r) = -13 for cluster member galaxies). Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between sources powered by an active nucleus and sources powered by active star formation. The radio-detected star-forming galaxies are restricted to radio luminosities between about 10(exp 21) and 10(exp 22) W/Hz, an interesting result given that star formation dominates field radio luminosity functions below about 10(exp 23) W/Hz. The majority of the radio-detected star-forming galaxies have characteristics of starbursts, including high specific star formation rates and optical spectra with strong emission lines. In conjunction with prior studies on post-starburst galaxies within the Coma cluster, this is consistent with a picture in which late-type galaxies entering Coma undergo a starburst prior to a rapid cessation of star formation. Optically bright elliptical galaxies (Mr less than or equals -20.5) make the largest contribution to the radio luminosity function at both the high (> approx. 3x10(exp 22) W/Hz) and low (< approx. 10(exp 21) W/Hz) ends. Through a stacking analysis of these optically-bright ellipticals we find that they continue to harbor radio sources down to luminosities as faint as 3x10(exp 19) W/Hz. However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint (M(sub r) approx. equals -14) dwarf ellipticals hosting strong radio AGN.

  10. SMA Observations of the Extended CO(6-5) Emission in the Starburst Galaxy NGC253

    Krips, Melanie; Peck, Alison; Sakamoto, Kazushi; Neri, Roberto; Gurwell, Mark; Petitpas, Glen; Zhao, Jun-Hui

    2016-01-01

    We present observations of the $^{12}$CO(6-5) line and 686GHz continuum emission in NGC253 with the Submillimeter Array at an angular resolution of ~4arcsec. The $^{12}$CO(6-5) emission is clearly detected along the disk and follows the distribution of the lower $^{12}$CO line transitions with little variations of the line ratios in it. A large-velocity gradient analysis suggests a two-temperature model of the molecular gas in the disk, likely dominated by a combination of low-velocity shocks and the disk wide PDRs. Only marginal $^{12}$CO(6-5) emission is detected in the vicinity of the expanding shells at the eastern and western edges of the disk. While the eastern shell contains gas even warmer (T$_{\\rm kin}$>300~K) than the hot gas component (T$_{\\rm kin}$=300K) of the disk, the western shell is surrounded by gas much cooler (T$_{\\rm kin}$=60K) than the eastern shell but somewhat hotter than the cold gas component of the disk (for similar H$_2$ and CO column densities), indicative of different (or differe...

  11. Mass and metal ejection efficiency in disk galaxies driven by young stellar clusters of nuclear starburst

    A. Rodríguez-González

    2011-01-01

    Full Text Available Presentamos las eficiencias de pérdida de masa y metales obtenidas de modelos numéricos de vientos galácticos empujados por la energía depositada en brotes de formación estelar nucleares. Los brotes de formación estelar contienen cúmulos estelares jóvenes los cuales inyectan la energía suficiente para empujar parte del medio interestelar fuera de las galaxias. En algunos casos los vientos galácticos contienen una importante parte de los metales producidos por las nuevas generaciones estelares. Para estudiar las eficiencias de pérdida de masa y metales hemos desarrollado simulaciones numéricas 3D N-Cuerpos/Smooth Particle Hydrodynamics de vientos galácticos para los casos: adiabáticos y con pérdidas radiativas. Los modelos numéricos cubren una amplio intervalo de masas de los brotes de formación estelar (de ∼ 10 2 a ∼ 10 7 M ⊙ y de masas en las galaxias anfitrionas (de ∼ 6 × 10 6 a ∼ 10 11 M ⊙. Las regiones de formación estelar concentradas en el centro del potencial son una maquinaria importante para la pérdida y redistribución de mas a y metales en este tipo de galaxias.

  12. MASS AND METAL EJECTION EFFICIENCY IN DISK GALAXIES DRIVEN BY YOUNG STELLAR CLUSTERS OF NUCLEAR STARBURST

    A. Rodríguez-González

    2011-01-01

    Full Text Available Presentamos las eficiencias de pérdida de masa obtenidas de modelos numéricos de vientos galácticos empujados por la energía depositada en brotes de formación estelar nucleares. Los brotes de formación estelar contienen cúmulos estelares jóvenes los cuales inyectan la energía suficiente para empujar parte del medio interestelar fuera de las galaxias. En algunos casos los vientos galácticos contienen una importante parte de los metales producidos por las nuevas generaciones estelares. Para estudiar las eficiencias de pérdida de masa hemos desarrollado simulaciones numéricas 3D "N-Body/Smooth Particle Hydrodynamics" de vientos galácticos para el caso con pérdidas radiativas. Los modelos numéricos cubren una amplio intervalo de masas en los brotes de formación estelar (de -102 a -107 M¿ y de masas en las galaxias anfitrionas (de -6×106 a -1011 M¿. Las regiones de formación estelar concentradas en el centro del potencial, son una maquinaria importante para la pérdida y redistribución de masa y metales en este tipo de galaxias.

  13. Clustering, host halos and environment of z$\\sim$2 galaxies as a function of their physical properties

    Bethermin, Matthieu; Daddi, Emanuele; Gabor, Jared; Finoguenov, Alexis; McCracken, Henry; Wolk, Melody; Aussel, Herve; Strazzulo, Veronica; Floc'h, Emeric Le; Gobat, Raphael; Rodighiero, Giulia; Dickinson, Mark; Wang, Lingyu; Lutz, Dieter; Heinis, Sebastien

    2014-01-01

    Using a sample of 25683 star-forming and 2821 passive galaxies at $z\\sim2$, selected in the COSMOS field following the BzK color criterion, we study the hosting halo mass and environment of galaxies as a function of their physical properties. Spitzer and Herschel provide accurate SFR estimates for starburst galaxies. We measure the auto- and cross-correlation functions of various galaxy sub-samples and infer the properties of their hosting halos using both an HOD model and the linear bias at large scale. We find that passive and star-forming galaxies obey a similarly rising relation between the halo and stellar mass. The mean host halo mass of star forming galaxies increases with the star formation rate between 30 and 200 M$_\\odot$.yr$^{-1}$, but flattens for higher values, except if we select only main-sequence galaxies. This reflects the expected transition from a regime of secular co-evolution of the halos and the galaxies to a regime of episodic starburst. We find similar large scale biases for main-seque...

  14. Peas in a Pod: Environment and Ionization in Green Pea Galaxies

    Kurtz, Heather; Jaskot, Anne; Drew, Patrick; Pare, Dylan; Griffin, Jon; Petersen, Michael

    2016-01-01

    The Green Peas are extreme, highly ionized, starburst galaxies with strong [OIII] 5007 emission. Using the Sloan Digital Sky Survey, we present statistics on the environment of Green Peas and investigate its effects on their ionized gas properties. Although most dwarf starburst galaxies are in low-density environments, we identify a sample of Green Peas in dense environments. Emission line observations with the WIYN 0.9-meter telescope at Kitt Peak reveal that one cluster Green Pea is more highly ionized in the direction of the cluster center. Ram pressure stripping likely generates this ionization gradient. We explore the role of the environment in enhancing star formation rates and ionization, and we compare the nebular properties of Green Peas in high-density environments to those in low-density environments.

  15. The BeppoSAX spectrum of the composite galaxy Mrk609

    Pappa, A; Ward, M; Zezas, A L

    2002-01-01

    We present Bepposax observations of the starburst/Seyfert composite galaxy Mrk609. This enigmatic object has an optical spectrum dominated by the features of starburst galaxies, yet its X-ray luminosity (6.3$\\times10^{42}$\\lunits) is typical of an AGN. The X-ray spectrum of Mrk609 can be parameterised by a single power-law model with a photon index $\\Gamma\\sim1.6\\pm0.1$ and no evidence for significant absorption above the Galactic value. Long term variability in both the 0.1-2 keV and 2-10 keV energy bands is detected, again suggesting that the X-ray emission is dominated by an AGN. The observed broad Ha component is a factor of 40 below that predicted by the X-ray flux implying a deficit of ionizing UV photons.

  16. A Companion Galaxy to the Poststarburst Quasar UN J1025-0040

    UN J1025-0040 is a quasar at z=0.6344 that shows an extremely bright post starburst population of age ∼400 Myr (Brotherton et al.). Images of UN J1025-0040 show a nearly stellar object 4(arc-seconds sign)2 south-southwest of the quasar. We present imaging and spectroscopy that confirm that this object is a companion galaxy at redshift z=0.6341. We estimate an age of ∼800 Myr for the dominant stellar population in the companion. The companion appears to be interacting with the quasar host galaxy, and this interaction may have triggered both the starburst and the quasar activity in UN J1025-0040. (c) (c) 2000. The American Astronomical Society

  17. 60 micron luminosity evolution of rich clusters of galaxies

    Kelly, D.M.; Rieke, G.H. (Steward Observatory, Tucson, AZ (USA))

    1990-10-01

    The average 60-micron flux has been determined for a collection of optically selected galaxy clusters at redshifts ranging from 0.30 to 0.92. The result, 26 mJy per cluster, represents the faintest flux determination known of using the IRAS data base. The flux from this set of clusters has been compared to the 60-micron flux from a sample of nearby galaxy clusters. It is found that the far-infrared luminosity evolution in cluster galaxies can be no more than a factor of 1.7 from z = 0.4 to the present epoch. This upper limit is close to the evolution predicted for simple aging of the stellar populations. Additional processes such as mergers, cannibalism, or enhanced rates of starbursts appear to occur at a low enough level that they have little influence on the far-infrared emission from clusters over this redshift range. 38 refs.

  18. Searching for molecular outflows in Hyper-Luminous Infrared Galaxies

    Calderón, D; Veilleux, S; Graciá-Carpio, J; Sturm, E; Lira, P; Schulze, S; Kim, S

    2016-01-01

    We present constraints on the molecular outflows in a sample of five Hyper-Luminous Infrared Galaxies using Herschel observations of the OH doublet at 119 {\\mu}m. We have detected the OH doublet in three cases: one purely in emission and two purely in absorption. The observed emission profile has a significant blueshifted wing suggesting the possibility of tracing an outflow. Out of the two absorption profiles, one seems to be consistent with the systemic velocity while the other clearly indicates the presence of a molecular outflow whose maximum velocity is about ~1500 km/s. Our analysis shows that this system is in general agreement with previous results on Ultra-luminous Infrared Galaxies and QSOs, whose outflow velocities do not seem to correlate with stellar masses or starburst luminosities (star formation rates). Instead the galaxy outflow likely arises from an embedded AGN.

  19. The peculiar galaxy IC 1182: An ongoing merger?

    Moles, M.; Bettoni, D.; Fasano, G.; Kjærgaard, P.; Varela, J.; Milvang-Jensen, B.

    2004-05-01

    High resolution broad and narrow band images and long slit spectroscopy of the peculiar galaxy IC 1182 are presented. The analysis of the broad band images reveals a distorted morphology with a large, heavily obscured disk-like structure and several knots in the central region. Galactic material, some of it in the form of two slender tails, is detected well beyond the main body of the galaxy. The second, fainter tail and several knots are reported here for the first time. The galaxy has color indices of an early type object except U-B, which is significantly bluer than what is typical for this kind of galaxy. The narrow band images centered on different emission lines show that the galaxy is a very powerful emitter. Most of the knots detected in the central region and in the prominent tail emerging eastward from the galaxy are very luminous in Hα, and have typical sizes about 1 kpc (FWHM). The emission in the main lines extends all over the galaxy, with plumes and arc-like structures seen in Hα at large distances from the center. The observed, uncorrected Hα flux corresponds to a total luminosity of 3.51 × 1041 erg s-1, about 3 times that of the starburst galaxy Arp 220. We have found that the internal extinction deduced from the observed Balmer decrement is high all along the slit, with EB-V≈ 1, so the corrected SFR could amount to 90 M⊙ per year. On this basis IC 1182 is found to be a very powerful starburst galaxy. Surprisingly, the source is not in the IRAS Point Source Catalogue. The emission knots detected in the central region of the galaxy have line ratios that place them close to the border of the region occupied by active nuclei in the diagnostic diagrams. Using the best determined diagnostic ratio, [O III]/Hβ vs. [N II]/Hα, they can still be classified as extreme HII-like regions. We notice that the same kind of line ratios are also measured at different places in the galaxy, adding to the idea that the nuclear line ratios can be explained in

  20. Misalignment between cold gas and stellar components in early-type galaxies

    Wong, O Ivy; Józsa, G I G; Urry, C M; Lintott, C J; Simmons, B D; Kaviraj, S; Masters, K L

    2015-01-01

    Recent work suggests blue ellipticals form in mergers and migrate quickly from the blue cloud of star-forming galaxies to the red sequence of passively evolving galaxies, perhaps as a result of black hole feedback. Such rapid reddening of stellar populations implies that large gas reservoirs in the pre-merger star-forming pair must be depleted on short time scales. Here we present pilot observations of atomic hydrogen gas in four blue early-type galaxies that reveal increasing spatial offsets between the gas reservoirs and the stellar components of the galaxies, with advancing post-starburst age. Emission line spectra show associated nuclear activity in two of the merged galaxies, and in one case radio lobes aligned with the displaced gas reservoir. These early results suggest that a kinetic process (possibly feedback from black hole activity) is driving the quick truncation of star formation in these systems, rather than a simple exhaustion of gas supply.