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Sample records for massive relaxed galaxy

  1. The flat density profiles of massive, and relaxed galaxy clusters

    SciTech Connect

    Popolo, A. Del

    2014-07-01

    The present paper is an extension and continuation of Del Popolo (2012a) which studied the role of baryon physics on clusters of galaxies formation. In the present paper, we studied by means of the SIM introduced in Del Popolo (2009), the total and DM density profiles, and the correlations among different quantities, observed by Newman et al. (2012a,b), in seven massive and relaxed clusters, namely MS2137, A963, A383, A611, A2537, A2667, A2390. As already found in Del Popolo 2012a, the density profiles depend on baryonic fraction, angular momentum, and the angular momentum transferred from baryons to DM through dynamical friction. Similarly to Newman et al. (2012a,b), the total density profile, in the radius range 0.003–0.03r{sub 200}, has a mean total density profile in agreement with dissipationless simulations. The slope of the DM profiles of all clusters is flatter than -1. The slope, α, has a maximum value (including errors) of α = −0.88 in the case of A2390, and minimum value α = −0.14 for A2537. The baryonic component dominates the mass distribution at radii < 5–10 kpc, while the outer distribution is dark matter dominated. We found an anti-correlation among the slope α, the effective radius, R{sub e}, and the BCG mass, and a correlation among the core radius r{sub core}, and R{sub e}. Moreover, the mass in 100 kpc (mainly dark matter) is correlated with the mass inside 5 kpc (mainly baryons). The behavior of the total mass density profile, the DM density profile, and the quoted correlations can be understood in a double phase scenario. In the first dissipative phase the proto-BCG forms, and in the second dissipationless phase, dynamical friction between baryonic clumps (collapsing to the center) and the DM halo flattens the inner slope of the density profile. In simple terms, the large scatter in the inner slope from cluster to cluster, and the anti-correlation among the slope, α and R{sub e} is due to the fact that in order to have a total

  2. LONG-TERM EVOLUTION OF MASSIVE BLACK HOLE BINARIES. IV. MERGERS OF GALAXIES WITH COLLISIONALLY RELAXED NUCLEI

    SciTech Connect

    Gualandris, Alessia; Merritt, David

    2012-01-01

    We simulate mergers between galaxies containing collisionally relaxed nuclei around massive black holes (MBHs). Our galaxies contain four mass groups, representative of old stellar populations; a primary goal is to understand the distribution of stellar-mass black holes (BHs) after the merger. Mergers are followed using direct-summation N-body simulations, assuming a mass ratio of 1:3 and two different orbits. Evolution of the binary MBH is followed until its separation has shrunk by a factor of 20 below the hard-binary separation. During the galaxy merger, large cores are carved out in the stellar distribution, with radii several times the influence radius of the massive binary. Much of the pre-existing mass segregation is erased during this phase. We follow the evolution of the merged galaxies for approximately three central relaxation times after coalescence of the massive binary; both standard and top-heavy mass functions are considered. The cores that were formed in the stellar distribution persist, and the distribution of the stellar-mass BHs evolves against this essentially fixed background. Even after one central relaxation time, these models look very different from the relaxed, multi-mass models that are often assumed to describe the distribution of stars and stellar remnants near a massive BH. While the stellar BHs do form a cusp on roughly a relaxation timescale, the BH density can be much smaller than in those models. We discuss the implications of our results for the extreme-mass-ratio inspiral problem and for the existence of Bahcall-Wolf cusps.

  3. The Dark Matter Halos of Massive, Relaxed Galaxy Clusters Observed With Chandra

    SciTech Connect

    Schmidt, Robert W.; Allen, S.W.; /KIPAC, Menlo Park

    2006-10-11

    We use the Chandra X-ray Observatory to study the dark matter halos of 34 massive, dynamically relaxed galaxy clusters, spanning the redshift range 0.06 < z < 0.7. The observed dark matter and total mass (dark-plus-luminous matter) profiles can be approximated by the Navarro Frenk & White (hereafter NFW) model for cold dark matter (CDM) halos; for {approx} 80 percent of the clusters, the NFW model provides a statistically acceptable fit. In contrast, the singular isothermal sphere model can, in almost every case, be completely ruled out. We observe a well-defined mass-concentration relation for the clusters with a normalization and intrinsic scatter in good agreement with the predictions from simulations. The slope of the mass-concentration relation, c {infinity} M{sub vir}{sup a}/(1 + z){sup b} with a = -0.41 {+-} 0.11 at 95 percent confidence, is steeper than the value a {approx} -0.1 predicted by CDM simulations for lower mass halos. With the slope a included as a free fit parameter, the redshift evolution of the concentration parameter, b = 0.54 {+-} 0.47 at 95 percent confidence, is also slower than, but marginally consistent with, the same simulations (b {approx} 1). Fixing a {approx} -0.1 leads to an apparent evolution that is significantly slower, b = 0.20 {+-} 0.45, although the goodness of fit in this case is significantly worse. Using a generalized NFW model, we find the inner dark matter density slope, a, to be consistent with unity at 95 percent confidence for the majority of clusters. Combining the results for all clusters for which the generalized NFW model provides a good description of the data, we measure ? = 0.88 {+-} 0.29 at 95 percent confidence, in agreement with CDM model predictions.

  4. THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. II. SEPARATING LUMINOUS AND DARK MATTER IN CLUSTER CORES

    SciTech Connect

    Newman, Andrew B.; Ellis, Richard S.; Treu, Tommaso; Sand, David J.

    2013-03-01

    We present stellar and dark matter (DM) density profiles for a sample of seven massive, relaxed galaxy clusters derived from strong and weak gravitational lensing and resolved stellar kinematic observations within the centrally located brightest cluster galaxies (BCGs). In Paper I of the series, we demonstrated that the total density profile derived from these data, which span three decades in radius, is consistent with numerical DM-only simulations at radii {approx}> 5-10 kpc, despite the significant contribution of stellar material in the core. Here, we decompose the inner mass profiles of these clusters into stellar and dark components. Parameterizing the DM density profile as a power law {rho}{sub DM}{proportional_to}r {sup -{beta}} on small scales, we find a mean slope ({beta}) = 0.50 {+-} 0.10(random){sup +0.14} {sub -0.13}(systematic). Alternatively, cored Navarro-Frenk-White (NFW) profiles with (log r {sub core}/kpc) = 1.14 {+-} 0.13{sup +0.14} {sub -0.22} provide an equally good description. These density profiles are significantly shallower than canonical NFW models at radii {approx}< 30 kpc, comparable to the effective radii of the BCGs. The inner DM profile is correlated with the distribution of stars in the BCG, suggesting a connection between the inner halo and the assembly of stars in the central galaxy. The stellar mass-to-light ratio inferred from lensing and stellar dynamics is consistent with that inferred using stellar population synthesis models if a Salpeter initial mass function is adopted. We compare these results to theories describing the interaction between baryons and DM in cluster cores, including adiabatic contraction models and the possible effects of galaxy mergers and active galactic nucleus feedback, and evaluate possible signatures of alternative DM candidates.

  5. MACS J1423.8+2404: gravitational lensing by a massive, relaxed cluster of galaxies at z = 0.54

    NASA Astrophysics Data System (ADS)

    Limousin, M.; Ebeling, H.; Ma, C.-J.; Swinbank, A. M.; Smith, G. P.; Richard, J.; Edge, A. C.; Jauzac, M.; Kneib, J.-P.; Marshall, P.; Schrabback, T.

    2010-06-01

    We present results of a gravitational lensing and optical study of MACS J1423.8+2404 (z = 0.545, MACS J1423), the most relaxed cluster in the high-redshift subsample of clusters discovered in the MAssive Cluster Survey (MACS). Our analysis uses high-resolution images taken with the Hubble Space Telescope in the F555W and F814W passbands, ground-based imaging in eight optical and near-infrared filters obtained with Subaru and Canada-France-Hawaii Telescope, as well as extensive spectroscopic data gathered with the Keck telescopes. At optical wavelengths, the cluster exhibits no sign of substructure and is dominated by a cD galaxy that is 2.1 mag (K band) brighter than the second brightest cluster member, suggesting that MACS J1423 is close to be fully virialized. Analysis of the redshift distribution of 140 cluster members reveals a Gaussian distribution, mildly disturbed by the presence of a loose galaxy group that may be falling into the cluster along the line of sight. Combining strong-lensing constraints from two spectroscopically confirmed multiple-image systems near the cluster core with a weak-lensing measurement of the gravitational shear on larger scales, we derive a parametric mass model for the mass distribution. All constraints can be satisfied by a unimodal mass distribution centred on the cD galaxy and exhibiting very little substructure. The derived projected mass of M[< 65 arcsec (415kpc)] = (4.3 +/- 0.6) × 1014 Msolar is about 30 per cent higher than the one derived from X-ray analyses assuming spherical symmetry, suggesting a slightly prolate mass distribution consistent with the optical indication of residual line-of-sight structure. The similarity in shape and excellent alignment of the centroids of the total mass, K-band light and intracluster gas distributions add to the picture of a highly evolved system. The existence of a massive cluster like MACS J1423, nearly fully virialized only ~7 Gyr after the big bang, may have important implications

  6. THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. I. THE TOTAL DENSITY OVER THREE DECADES IN RADIUS

    SciTech Connect

    Newman, Andrew B.; Ellis, Richard S.; Treu, Tommaso; Sand, David J.; Nipoti, Carlo; Richard, Johan; Jullo, Eric

    2013-03-01

    Clusters of galaxies are excellent locations to probe the distribution of baryons and dark matter (DM) over a wide range of scales. We study a sample of seven massive (M {sub 200} = 0.4-2 Multiplication-Sign 10{sup 15} M {sub Sun }), relaxed galaxy clusters with centrally located brightest cluster galaxies (BCGs) at z = 0.2-0.3. Using the observational tools of strong and weak gravitational lensing, combined with resolved stellar kinematics within the BCG, we measure the total radial density profile, comprising both dark and baryonic matter, over scales of {approx_equal} 3-3000 kpc. We present Keck spectroscopy yielding seven new spectroscopic redshifts of multiply imaged sources and extended stellar velocity dispersion profiles of the BCGs. Lensing-derived mass profiles typically agree with independent X-ray estimates within {approx_equal} 15%, suggesting that departures from hydrostatic equilibrium are small and that the clusters in our sample (except A383) are not strongly elongated or compressed along the line of sight. The inner logarithmic slope {gamma}{sub tot} of the total density profile measured over r/r {sub 200} = 0.003-0.03, where {rho}{sub tot}{proportional_to}r{sup -{gamma}{sub t}{sub o}{sub t}}, is found to be nearly universal, with a mean ({gamma}{sub tot}) = 1.16 {+-} 0.05(random){sup +0.05} {sub -0.07} (systematic) and an intrinsic scatter {sigma}{sub {gamma}} < 0.13 (68% confidence). This is further supported by the very homogeneous shape of the observed velocity dispersion profiles, which are mutually consistent after a simple scaling. Remarkably, this slope agrees closely with high-resolution numerical simulations that contain only DM, despite the significant contribution of stellar mass on the scales we probe. The Navarro-Frenk-White profile characteristic of collisionless cold DM is a better description of the total mass density at radii {approx}> 5-10 kpc than that of DM alone. Hydrodynamical simulations that include baryons, cooling, and

  7. Massive star clusters in galaxies.

    PubMed

    Harris, William E

    2010-02-28

    The ensemble of all star clusters in a galaxy constitutes its star cluster system. In this review, the focus of the discussion is on the ability of star clusters, particularly the systems of old massive globular clusters (GCs), to mark the early evolutionary history of galaxies. I review current themes and key findings in GC research, and highlight some of the outstanding questions that are emerging from recent work.

  8. HST Infrared Imaging of MASSIVE Survey Galaxies

    NASA Astrophysics Data System (ADS)

    Jensen, Joseph B.; Goullaud, Charles; Blakeslee, John; Mitchiner, Casey; Ma, Chung-Pei; Greene, Jenny E.; McConnell, Nicholas J.; Thomas, Jens

    2017-01-01

    We have recently obtained high-resolution HST WFC3/IR F110W (J-band) images of 34 early-type galaxies in the MASSIVE study sample. These galaxies are among the most massive in the local universe, and were chosen to study the connection between supermassive central black holes and their host galaxies. To determine accurate masses for the black holes, we are measuring high-precision surface brightness fluctuation (SBF) distances to the galaxies. The WFC3/IR data also allow us to measure high spatial resolution central surface brightness profiles to understand better the nuclear structure and dynamics of the galaxies. We present a first look at the IR images, profiles, and SBF magnitudes for 34 galaxies in the MASSIVE sample.

  9. Inside-out formation of massive galaxies

    NASA Astrophysics Data System (ADS)

    de la Rosa, I. G.

    2017-03-01

    A significant fraction of the present day massive galaxies have compact cores embedded inside their disks or halos. Strikingly, those compact cores are similar to the massive high-redshift quiescent compact galaxies, nicknamed red-nuggets. We present observational evidence supporting an inside-out formation scenario, where present-day massive galaxies can begin as dense spheroidal cores (red-nuggets), around which either a spheroidal halo or a disk are accreted later. This contribution is based on the paper by de la Rosa et al. (2016).

  10. Dwarf Galaxies with Active Massive Black Holes

    NASA Astrophysics Data System (ADS)

    Reines, Amy E.; Greene, J. E.; Geha, M. C.

    2014-01-01

    Supermassive black holes (BHs) live at the heart of essentially all massive galaxies with bulges, power AGN, and are thought to be important agents in the evolution of their hosts. However, the birth and growth of the first supermassive BH "seeds" is far from understood. While direct observations of these distant BHs in the infant Universe are unobtainable with current capabilities, massive BHs in present-day dwarf galaxies can place valuable constraints on the masses, formation path, and hosts of supermassive BH seeds. Using optical spectroscopy from the SDSS, we have systematically assembled the largest sample of dwarf galaxies hosting active massive BHs to date. These dwarf galaxies have stellar masses comparable to the Magellanic Clouds and contain some of the least-massive supermassive BHs known.

  11. SUPERDENSE MASSIVE GALAXIES IN WINGS LOCAL CLUSTERS

    SciTech Connect

    Valentinuzzi, T.; D'Onofrio, M.; Fritz, J.; Poggianti, B. M.; Bettoni, D.; Fasano, G.; Moretti, A.; Omizzolo, A.; Varela, J.; Cava, A.; Couch, W. J.; Dressler, A.; Moles, M.; Kjaergaard, P.; Vanzella, E.

    2010-03-20

    Massive quiescent galaxies at z > 1 have been found to have small physical sizes, and hence to be superdense. Several mechanisms, including minor mergers, have been proposed for increasing galaxy sizes from high- to low-z. We search for superdense massive galaxies in the WIde-field Nearby Galaxy-cluster Survey (WINGS) of X-ray selected galaxy clusters at 0.04 < z < 0.07. We discover a significant population of superdense massive galaxies with masses and sizes comparable to those observed at high redshift. They approximately represent 22% of all cluster galaxies more massive than 3 x 10{sup 10} M{sub sun}, are mostly S0 galaxies, have a median effective radius (R{sub e} ) = 1.61 +- 0.29 kpc, a median Sersic index (n) = 3.0 +- 0.6, and very old stellar populations with a median mass-weighted age of 12.1 +- 1.3 Gyr. We calculate a number density of 2.9 x 10{sup -2} Mpc{sup -3} for superdense galaxies in local clusters, and a hard lower limit of 1.3 x 10{sup -5} Mpc{sup -3} in the whole comoving volume between z = 0.04 and z = 0.07. We find a relation between mass, effective radius, and luminosity-weighted age in our cluster galaxies, which can mimic the claimed evolution of the radius with redshift, if not properly taken into account. We compare our data with spectroscopic high-z surveys and find that-when stellar masses are considered-there is consistency with the local WINGS galaxy sizes out to z {approx} 2, while a discrepancy of a factor of 3 exists with the only spectroscopic z > 2 study. In contrast, there is strong evidence for a large evolution in radius for the most massive galaxies with M{sub *} > 4 x 10{sup 11} M{sub sun} compared to similarly massive galaxies in WINGS, i.e., the brightest cluster galaxies.

  12. Superdense massive galaxies in the nearby universe

    NASA Astrophysics Data System (ADS)

    Ferré-Mateu, Anna; Trujillo, Ignacio

    2010-04-01

    At high-z the most superdense massive galaxies are supposed to be the result of gas-rich mergers resulting in compact remnant (Khochfar & Silk (2006); Naab et al. (2007)). After this, dry mergers are expected to be the mechanism that moves these very massive galaxies towards the current stellar mass size relation. Whitin these merging scenarios, a non-negligible fraction (1-10%) of these galaxies is expected to survive since that epoch retaining their compactness and presenting old stellar populations in the past universe.Using the NYU Value-Added Galaxy Catalog (DR6), we find only a tiny fraction of galaxies (~0.03%) with re ≤ 1.5 kpc and M* ≥ 8x1010M⊙ in the local Universe (z~0.2). Surprisingly, they are relatively young (~2Gyr) and metal rich ([Z/H]~0.2) These results have been published in Trujillo et al. (2009)

  13. Models of violently relaxed galaxies

    NASA Astrophysics Data System (ADS)

    Merritt, David; Tremaine, Scott; Johnstone, Doug

    1989-02-01

    The properties of spherical self-gravitating models derived from two distribution functions that incorporate, in a crude way, the physics of violent relaxation are investigated. The first distribution function is identical to the one discussed by Stiavelli and Bertin (1985) except for a change in the sign of the 'temperature', i.e., e exp(-aE) to e exp(+aE). It is shown that these 'negative temperature' models provide a much better description of the end-state of violent relaxation than 'positive temperature' models. The second distribution function is similar to the first except for a different dependence on angular momentum. Both distribution functions yield single-parameter families of models with surface density profiles very similar to the R exp 1/4 law. Furthermore, the central concentration of models in both families increases monotonically with the velocity anisotropy, as expected in systems that formed through cold collapse.

  14. Dwarf galaxy evolution within the environments of massive galaxies

    NASA Astrophysics Data System (ADS)

    Arraki, Kenza S.; Klypin, Anatoly A.; Ceverino, Daniel; Trujillo-Gomez, Sebastian; Primack, Joel R.

    2016-01-01

    Understanding galaxy evolution depends on connecting large-scale structure determined by the ΛCDM model with, at minimum, the small-scale physics of gas, star formation, and stellar feedback. Formation of galaxies within dark matter halos is sensitive to the physical phenomena occurring within and around the halo. This is especially true for dwarf galaxies, which have the smallest potential wells and are more susceptible to the effects of gas ionization and removal than larger galaxies. At dwarf galaxies scales comparisons of dark matter-only simulations with observations has unveiled various differences including the core-cusp, the missing satellites, and the too-big-to-fail problems. We have run a new suite of hydrodynamical simulations using the ART code to examine the evolution of dwarf galaxies in massive host environments. These are cosmological zoom-in simulations including deterministic star formation and stellar feedback in the form of supernovae feedback, stellar winds, radiation pressure, and photoionization pressure. We simulates galaxies with final halo masses on the order of 1012 M⊙ with high resolution, allowing us to examine the satellite dwarf galaxies and local isolated dwarf galaxies around each primary galaxy. We analyzed the abundance and structure of these dwarfs specifically the velocity function, their star formation rates, core creation and the circumgalactic medium. By reproducing observations of dwarf galaxies in simulations we show how including baryons in simulations relieves tensions seen in comparing dark matter only simulations with observations.

  15. THE STELLAR HALOS OF MASSIVE ELLIPTICAL GALAXIES

    SciTech Connect

    Greene, Jenny E.; Murphy, Jeremy D.; Comerford, Julia M.; Gebhardt, Karl; Adams, Joshua J.

    2012-05-01

    We use the Mitchell Spectrograph (formerly VIRUS-P) on the McDonald Observatory 2.7 m Harlan J. Smith Telescope to search for the chemical signatures of massive elliptical galaxy assembly. The Mitchell Spectrograph is an integral-field spectrograph with a uniquely wide field of view (107'' Multiplication-Sign 107''), allowing us to achieve remarkably high signal-to-noise ratios of {approx}20-70 pixel{sup -1} in radial bins of 2-2.5 times the effective radii of the eight galaxies in our sample. Focusing on a sample of massive elliptical galaxies with stellar velocity dispersions {sigma}{sub *} > 150 km s{sup -1}, we study the radial dependence in the equivalent widths (EW) of key metal absorption lines. By twice the effective radius, the Mgb EWs have dropped by {approx}50%, and only a weak correlation between {sigma}{sub *} and Mgb EW remains. The Mgb EWs at large radii are comparable to those seen in the centers of elliptical galaxies that are {approx} an order of magnitude less massive. We find that the well-known metallicity gradients often observed within an effective radius continue smoothly to 2.5 R{sub e} , while the abundance ratio gradients remain flat. Much like the halo of the Milky Way, the stellar halos of our galaxies have low metallicities and high {alpha}-abundance ratios, as expected for very old stars formed in small stellar systems. Our observations support a picture in which the outer parts of massive elliptical galaxies are built by the accretion of much smaller systems whose star formation history was truncated at early times.

  16. The Stellar Halos of Massive Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Greene, Jenny E.; Murphy, Jeremy D.; Comerford, Julia M.; Gebhardt, Karl; Adams, Joshua J.

    2012-05-01

    We use the Mitchell Spectrograph (formerly VIRUS-P) on the McDonald Observatory 2.7 m Harlan J. Smith Telescope to search for the chemical signatures of massive elliptical galaxy assembly. The Mitchell Spectrograph is an integral-field spectrograph with a uniquely wide field of view (107'' × 107''), allowing us to achieve remarkably high signal-to-noise ratios of ~20-70 pixel-1 in radial bins of 2-2.5 times the effective radii of the eight galaxies in our sample. Focusing on a sample of massive elliptical galaxies with stellar velocity dispersions σ* > 150 km s-1, we study the radial dependence in the equivalent widths (EW) of key metal absorption lines. By twice the effective radius, the Mgb EWs have dropped by ~50%, and only a weak correlation between σ* and Mgb EW remains. The Mgb EWs at large radii are comparable to those seen in the centers of elliptical galaxies that are ~ an order of magnitude less massive. We find that the well-known metallicity gradients often observed within an effective radius continue smoothly to 2.5 Re , while the abundance ratio gradients remain flat. Much like the halo of the Milky Way, the stellar halos of our galaxies have low metallicities and high α-abundance ratios, as expected for very old stars formed in small stellar systems. Our observations support a picture in which the outer parts of massive elliptical galaxies are built by the accretion of much smaller systems whose star formation history was truncated at early times.

  17. SEGUE 2: THE LEAST MASSIVE GALAXY

    SciTech Connect

    Kirby, Evan N.; Boylan-Kolchin, Michael; Bullock, James S.; Kaplinghat, Manoj; Cohen, Judith G.; Geha, Marla

    2013-06-10

    Segue 2, discovered by Belokurov et al., is a galaxy with a luminosity of only 900 L{sub Sun }. We present Keck/DEIMOS spectroscopy of 25 members of Segue 2-a threefold increase in spectroscopic sample size. The velocity dispersion is too small to be measured with our data. The upper limit with 90% (95%) confidence is {sigma}{sub v} < 2.2 (2.6) km s{sup -1}, the most stringent limit for any galaxy. The corresponding limit on the mass within the three-dimensional half-light radius (46 pc) is M{sub 1/2} < 1.5 (2.1) Multiplication-Sign 10{sup 5} M{sub Sun }. Segue 2 is the least massive galaxy known. We identify Segue 2 as a galaxy rather than a star cluster based on the wide dispersion in [Fe/H] (from -2.85 to -1.33) among the member stars. The stars' [{alpha}/Fe] ratios decline with increasing [Fe/H], indicating that Segue 2 retained Type Ia supernova ejecta despite its presently small mass and that star formation lasted for at least 100 Myr. The mean metallicity, ([Fe/H]) = -2.22 {+-} 0.13 (about the same as the Ursa Minor galaxy, 330 times more luminous than Segue 2), is higher than expected from the luminosity-metallicity relation defined by more luminous dwarf galaxy satellites of the Milky Way. Segue 2 may be the barest remnant of a tidally stripped, Ursa Minor-sized galaxy. If so, it is the best example of an ultra-faint dwarf galaxy that came to be ultra-faint through tidal stripping. Alternatively, Segue 2 could have been born in a very low mass dark matter subhalo (v{sub max} < 10 km s{sup -1}), below the atomic hydrogen cooling limit.

  18. The dynamical fingerprint of core scouring in massive elliptical galaxies

    SciTech Connect

    Thomas, J.; Saglia, R. P.; Bender, R.; Erwin, P.; Fabricius, M.

    2014-02-10

    The most massive elliptical galaxies have low-density centers or cores that differ dramatically from the high-density centers of less massive ellipticals and bulges of disk galaxies. These cores have been interpreted as the result of mergers of supermassive black hole binaries, which depopulate galaxy centers by gravitationally slingshotting central stars toward large radii. Such binaries naturally form in mergers of luminous galaxies. Here, we analyze the population of central stellar orbits in 11 massive elliptical galaxies that we observed with the integral field spectrograph SINFONI at the European Southern Observatory Very Large Telescope. Our dynamical analysis is orbit-based and includes the effects of a central black hole, the mass distribution of the stars, and a dark matter halo. We show that the use of integral field kinematics and the inclusion of dark matter is important to conclude on the distribution of stellar orbits in galaxy centers. Six of our galaxies are core galaxies. In these six galaxies, but not in the galaxies without cores, we detect a coherent lack of stars on radial orbits in the core region and a uniform excess of radial orbits outside of it: when scaled by the core radius r{sub b} , the radial profiles of the classical anisotropy parameter β(r) are nearly identical in core galaxies. Moreover, they quantitatively match the predictions of black hole binary simulations, providing the first convincing dynamical evidence for core scouring in the most massive elliptical galaxies.

  19. The origin of the α-enhancement of massive galaxies

    NASA Astrophysics Data System (ADS)

    Segers, Marijke C.; Schaye, Joop; Bower, Richard G.; Crain, Robert A.; Schaller, Matthieu; Theuns, Tom

    2016-09-01

    We study the origin of the stellar α-element-to-iron abundance ratio, [α/Fe]*, of present-day central galaxies, using cosmological, hydrodynamical simulations from the Evolution and Assembly of GaLaxies and their Environments (EAGLE) project. For galaxies with stellar masses of M* > 1010.5 M⊙, [α/Fe]* increases with increasing galaxy stellar mass and age. These trends are in good agreement with observations of early-type galaxies, and are consistent with a `downsizing' galaxy formation scenario: more massive galaxies have formed the bulk of their stars earlier and more rapidly, hence from an interstellar medium that was mostly α-enriched by massive stars. In the absence of feedback from active galactic nuclei (AGNs), however, [α/Fe]* in M* > 1010.5 M⊙ galaxies is roughly constant with stellar mass and decreases with mean stellar age, extending the trends found for lower mass galaxies in both simulations with and without AGN. We conclude that AGN feedback can account for the α-enhancement of massive galaxies, as it suppresses their star formation, quenching more massive galaxies at earlier times, thereby preventing the iron from longer lived intermediate-mass stars (supernova Type Ia) from being incorporated into younger stars.

  20. An over-massive black hole in the compact lenticular galaxy NGC 1277.

    PubMed

    van den Bosch, Remco C E; Gebhardt, Karl; Gültekin, Kayhan; van de Ven, Glenn; van der Wel, Arjen; Walsh, Jonelle L

    2012-11-29

    Most massive galaxies have supermassive black holes at their centres, and the masses of the black holes are believed to correlate with properties of the host-galaxy bulge component. Several explanations have been proposed for the existence of these locally established empirical relationships, including the non-causal, statistical process of galaxy-galaxy merging, direct feedback between the black hole and its host galaxy, and galaxy-galaxy merging and the subsequent violent relaxation and dissipation. The empirical scaling relations are therefore important for distinguishing between various theoretical models of galaxy evolution, and they furthermore form the basis for all black-hole mass measurements at large distances. Observations have shown that the mass of the black hole is typically 0.1 per cent of the mass of the stellar bulge of the galaxy. Until now, the galaxy with the largest known fraction of its mass in its central black hole (11 per cent) was the small galaxy NGC 4486B. Here we report observations of the stellar kinematics of NGC 1277, which is a compact, lenticular galaxy with a mass of 1.2 × 10(11) solar masses. From the data, we determine that the mass of the central black hole is 1.7 × 10(10) solar masses, or 59 per cent of its bulge mass. We also show observations of five other compact galaxies that have properties similar to NGC 1277 and therefore may also contain over-massive black holes. It is not yet known if these galaxies represent a tail of a distribution, or if disk-dominated galaxies fail to follow the usual black-hole mass scaling relations.

  1. Satellites around massive galaxies since z˜ 2

    NASA Astrophysics Data System (ADS)

    Mármol-Queraltó, E.; Trujillo, I.; Pérez-González, P. G.; Varela, J.; Barro, G.

    2012-05-01

    The accretion of minor satellites has been postulated as the most likely mechanism to explain the significant size evolution of massive galaxies over cosmic time. Using a sample of 629 massive (Mstar˜ 1011 M⊙) galaxies from the near-infrared Palomar/DEEP-2 survey, we explore what fraction of these objects have satellites with 0.01 < Msat/Mcentral < 1 (1:100) up to z= 1 and what fraction have satellites with 0.1 < Msat/Mcentral < 1 (1:10) up to z= 2 within a projected radial distance of 100 kpc. We find that the fraction of massive galaxies with satellites, after background correction, remains basically constant and close to 30 per cent for satellites with a mass ratio down to 1:100 up to z= 1, and close to 15 per cent for satellites with a 1:10 mass ratio up to z= 2. The family of spheroid-like massive galaxies presents a 2-3 times larger fraction of objects with satellites than the group of disc-like massive galaxies. A crude estimation of the number of 1:3 mergers a massive spheroid-like galaxy has experienced since z˜ 2 is around 2. For a disc-like galaxy this number decreases to ˜1.

  2. The Most Massive Black Holes in Small Galaxies

    NASA Astrophysics Data System (ADS)

    van den Bosch, Remco

    2012-10-01

    Massive galaxies represent the extreme of galaxy formation and contain the most massive black holes {BH}, as reflected in the scaling relations of BH masses with galaxy velocity dispersions {M-sigma} and luminosities {M-L}. Our spectroscopic survey of 600 nearby galaxies revealed 17 galaxies with extremely high velocity dispersions {indicating BH masses of 10^10 solar masses} and at the same time shockingly small sizes {<2 kpc} and {bulge} luminosities. For one of these galaxies archival HST imaging allowed us to measure an extremely big BH mass of 23 billion solar masses, and confirm it is hosted by a small disk-dominated galaxy of only 90 billion solar masses in stars. This demonstrates that the BH in this system did not co-evolve with its host galaxy the way others are thought to have. It is imperative to go beyond a single anecdotal example to a real sample of galaxies with small bulges and suspected monster black holes. Here we propose to obtain HST imaging of the other 16 galaxies. The WFC3 imaging is required to resolve their small bulge and put accurate constraints {in combination with our spectroscopy} on their black hole mass. A significant sample of compact galaxies with very high black hole masses would be in stark conflict with the popular co-evolution picture and could form the missing link between local galaxies and the quiescent compact nugget galaxies found at z 2.

  3. The role of stellar relaxation in the formation and evolution of the first massive black holes

    NASA Astrophysics Data System (ADS)

    Yajima, Hidenobu; Khochfar, Sadegh

    2016-04-01

    We present calculations on the formation of massive black holes of 105 M⊙ at z > 6, which can be the seeds of supermassive black holes at z ≳ 6. Under the assumption of compact star cluster formation in merging galaxies, star clusters in haloes of ˜ 108-109 M⊙ can undergo rapid core collapse, leading to the formation of very massive stars (VMSs) of ˜ 1000 M⊙ that collapse directly into black holes with similar masses. Star clusters in haloes of ≳ 109 M⊙ experience Type II supernovae before the formation of VMSs, due to long core-collapse time-scales. We also model the subsequent growth of black holes via accretion of residual stars in clusters. Two-body relaxation refills the loss cones of stellar orbits efficiently at larger radii and resonant relaxation at small radii is the main driver for accretion of stars on to black holes. As a result, more than 90 percent of stars in the initial cluster are swallowed by the central black holes before z = 6. Using dark matter merger trees, we derive black hole mass functions at z = 6-20. The mass function ranges from 103-105 M⊙ at z ≲ 15. Major merging of galaxies of ≳ 4 × 108 M⊙ at z ˜ 20 leads successfully to the formation of ≳ 105 M⊙ black holes by z ≳ 10, which could be the potential seeds of supermassive black holes seen today.

  4. THE MERGER-DRIVEN EVOLUTION OF MASSIVE GALAXIES

    SciTech Connect

    Robaina, Aday R.; Van der Wel, Arjen; Skelton, Rosalind E.; Meisenheimer, Klaus; Bell, Eric F.; Somerville, Rachel S.; McIntosh, Daniel H.; Wolf, Christian

    2010-08-10

    We explore the rate and impact of galaxy mergers on the massive galaxy population using the amplitude of the two-point correlation function on small scales for M {sub *} > 5 x 10{sup 10} M {sub sun} galaxies from the COSMOS and COMBO-17 surveys. Using a pair fraction derived from the Sloan Digital Sky Survey as a low-redshift benchmark, the large survey area at intermediate redshifts allows us to determine the evolution of the close-pair fraction with unprecedented accuracy for a mass-selected sample: we find that the fraction of galaxies more massive than 5 x 10{sup 10} M {sub sun} in pairs separated by less than 30 kpc in three-dimensional space evolves as F(z) = (0.0130 {+-} 0.0019) x (1 + z){sup 1.21{+-}0.25} between z = 0 and z = 1.2. Assuming a merger timescale of 0.5 Gyr, the inferred merger rate is such that galaxies with mass in excess of 10{sup 11} M {sub sun} have undergone, on average, 0.5 (0.7) mergers involving progenitor galaxies both more massive than 5 x 10{sup 10} M {sub sun} since z = 0.6 (1.2). We also study the number density evolution of massive red sequence galaxies using published luminosity functions and constraints on the M/L {sub B} evolution from the fundamental plane. Moreover, we demonstrate that the measured merger rate of massive galaxies is sufficient to explain this observed number density evolution in massive red sequence galaxies since z = 1.

  5. Role of Massive Stars in the Evolution of Primitive Galaxies

    NASA Technical Reports Server (NTRS)

    Heap, Sara

    2012-01-01

    An important factor controlling galaxy evolution is feedback from massive stars. It is believed that the nature and intensity of stellar feedback changes as a function of galaxy mass and metallicity. At low mass and metallicity, feedback from massive stars is mainly in the form of photoionizing radiation. At higher mass and metallicity, it is in stellar winds. IZw 18 is a local blue, compact dwarf galaxy that meets the requirements for a primitive galaxy: low halo mass greater than 10(exp 9)Msun, strong photoionizing radiation, no galactic outflow, and very low metallicity,log(O/H)+12=7.2. We will describe the properties of massive stars and their role in the evolution of IZw 18, based on analysis of ultraviolet images and spectra obtained with HST.

  6. ON THE ASSEMBLY HISTORY OF STELLAR COMPONENTS IN MASSIVE GALAXIES

    SciTech Connect

    Lee, Jaehyun; Yi, Sukyoung K.

    2013-03-20

    Matsuoka and Kawara showed that the number density of the most massive galaxies (log M/M{sub Sun} = 11.5-12.0) increases faster than that of the next massive group (log M/M{sub Sun} = 11.0-11.5) during 0 < z < 1. This appears to be in contradiction to the apparent 'downsizing effect'. We attempt to understand the two observational findings in the context of the hierarchical merger paradigm using semi-analytic techniques. Our models closely reproduce the result of Matsuoka and Kawara. Downsizing can also be understood as larger galaxies have, on average, smaller assembly ages but larger stellar ages. Our fiducial models further reveal details of the history of the stellar mass growth of massive galaxies. The most massive galaxies (log M/M{sub Sun} = 11.5-12.0 at z = 0), which are mostly the brightest cluster galaxies, obtain roughly 70% of their stellar components via merger accretion. The role of merger accretion monotonically declines with galaxy mass: 40% for log M/M{sub Sun} = 11.0-11.5 and 20% for log M/M{sub Sun} = 10.5-11.0 at z = 0. The specific accreted stellar mass rates via galaxy mergers decline very slowly during the whole redshift range, while specific star formation rates sharply decrease with time. In the case of the most massive galaxies, merger accretion becomes the most important channel for the stellar mass growth at z {approx} 2. On the other hand, in situ star formation is always the dominant channel in L{sub *} galaxies.

  7. Tracing the Formation and Evolution of Massive Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Davari, Roozbeh

    Massive galaxies at higher redshift, z > 2, show different characteristics than their local counterparts. They are compact and most likely have a disk. Understanding the evolutionary path of these massive galaxies can give us some clues on how the universe has been behaving in the last 10 billion years. How well can we measure the bulge and disk properties of these systems? We perform two sets of comprehensive simulations in order to systematically quantify the effects of non-homology in structures and the methods employed. For the first set of simulations, by accurately capturing the detailed substructures of nearby elliptical galaxies and then rescaling their sizes and signal-to-noise to mimic galaxies at different redshifts, we confirm that the massive quiescent galaxies at z ≈ 2 are significantly more compact intrinsically than their local counterparts. Their observed compactness is not a result of missing faint outer light due to systematic errors in modeling. For the second set of simulations, we employ empirical scaling relations to produce realistic-looking two-component local galaxies with a uniform and wide range of bulge-to-total ratios (B/T), and then rescale them to mimic the signal-to-noise ratios and sizes of observed galaxies at z ≈ 2. This provides the first set of simulations for which we can examine the robustness of two-component decomposition of compact disk galaxies at different B/T . We can measure B/T accurately without imposing any constraints on the light profile shape of the bulge, but, due to the small angular sizes of bulges at high redshift, their detailed properties can only be recovered for galaxies with B/T ≥ 0.2. The disk component, by contrast, can be measured with little difficulty. Next, we trace back the evolution of local massive galaxies but performing detailed morphological analysis: namely, single Swrsic fitting and bulge+disk decomposition. CANDELS images and catalogues offer an ideal dataset for this study. We

  8. Most Massive Globular Cluster in Our Galaxy

    NASA Astrophysics Data System (ADS)

    1994-05-01

    Far down in the southern sky, in the constellation of Centaurus, a diffuse spot of light can be perceived with the unaided eye. It may be unimpressive, but when seen through a telescope, it turns out to be a beautiful, dense cluster of innumerable stars [1]. Omega Centauri, as this object is called, is the brightest of its type in the sky. We refer to it as a "globular cluster", due to its symmetric form. It belongs to our Milky Way galaxy and astrophysical investigations have shown that it is located at a distance of about 16,500 light-years (1 light-year = 9,460,000,000,000 km). Nobody knows for sure how many individual stars it contains, but recent estimates run into the millions. Most of these stars are more than 10,000 million years old and it is generally agreed that Omega Centauri has a similar age. Measurements of its motion indicate that Omega Centauri plows through the Milky Way in an elongated orbit. It is not easy to understand how it has managed to keep its stars together during such an extended period. MEASURING STELLAR VELOCITIES IN OMEGA CENTAURI A group of astronomers [2] have recently carried through a major investigation of Omega Centauri. After many nights of observations at the ESO La Silla observatory, they now conclude that not only is this globular cluster the brightest, it is indeed by far the most massive known in the Milky Way. The very time-consuming observations were made during numerous observing sessions over a period of no less than 13 years (1981-1993), with the photoelectric spectrometer CORAVEL mounted on the 1.5-m Danish telescope at La Silla. The CORAVEL instrument (COrelation RAdial VELocities) was built in a joint effort between the Geneva (Switzerland) and Marseilles (France) observatories. It functions according to the cross-correlation technique, by means of which the spectrum of the observed star is compared with a "standard stellar spectrum" [3]. HOW HEAVY IS OMEGA CENTAURI? In the present study, a total of 1701

  9. Satellite galaxies: the infalling pieces of the puzzle of massive galaxies

    NASA Astrophysics Data System (ADS)

    Mármol-Queraltó, E.

    2013-05-01

    Accretion of minor satellites has been postulated as the most likely mechanism to explain the significant size evolution of the massive galaxies over cosmic time. A direct way of probing this scenario is to measure the frequency of satellites around massive galaxies at different redshifts. In this contribution, I present the study that we have performed to search for satellites around 629 massive ({M}_* ˜ 10^{11} {M}_{⊙}) galaxies up to z˜2 from the near-infrared Palomar/DEEP-2 survey. We find that the fraction of massive galaxies with satellites remains basically constant and close to 30% for satellites with a mass ratio down to 1:100 up to z=1, and ˜15% for satellites with a 1:10 mass ratio up to z=2. In addition, at low redshift the satellites are, in average, 1.5 Gyr younger than the massive galaxies that host them. In the minor merging model, this rejuvenated material is likely to be placed in the outskirts of the massive objects, and negative age gradients should be observed in local massive galaxies. Hence, this work gives new clues to explore the minor merging scenario from the study of nearby galaxies.

  10. STAR FORMATION AND RELAXATION IN 379 NEARBY GALAXY CLUSTERS

    SciTech Connect

    Cohen, Seth A.; Hickox, Ryan C.; Wegner, Gary A.

    2015-06-10

    We investigate the relationship between star formation (SF) and level of relaxation in a sample of 379 galaxy clusters at z < 0.2. We use data from the Sloan Digital Sky Survey to measure cluster membership and level of relaxation, and to select star-forming galaxies based on mid-infrared emission detected with the Wide-Field Infrared Survey Explorer. For galaxies with absolute magnitudes M{sub r} < −19.5, we find an inverse correlation between SF fraction and cluster relaxation: as a cluster becomes less relaxed, its SF fraction increases. Furthermore, in general, the subtracted SF fraction in all unrelaxed clusters (0.117 ± 0.003) is higher than that in all relaxed clusters (0.097 ± 0.005). We verify the validity of our SF calculation methods and membership criteria through analysis of previous work. Our results agree with previous findings that a weak correlation exists between cluster SF and dynamical state, possibly because unrelaxed clusters are less evolved relative to relaxed clusters.

  11. STELLAR ENERGY RELAXATION AROUND A MASSIVE BLACK HOLE

    SciTech Connect

    Bar-Or, Ben; Kupi, Gabor; Alexander, Tal

    2013-02-10

    Orbital energy relaxation around a massive black hole (MBH) plays a key role in the dynamics of galactic nuclei. Its standard description as diffusion provides a perturbative solution in the weak two-body interaction limit. Our N-body simulations show this fails to describe the short-timescale evolution, which is impacted by extreme events even in the weak limit, and is thus difficult to characterize and measure. We derive a non-perturbative solution for energy relaxation as an anomalous diffusion process, and a robust estimation technique to measure it in N-body simulations, and use these to analyze our numerical results. We empirically validate, for the first time, this theoretical description of energy relaxation around an MBH on all timescales. We constrain the modest contribution from strong encounters, and precisely measure that from the weakest encounters, and thereby calibrate the Coulomb logarithm. This yields a robust analytical estimate for the energy diffusion time, t{sub E} . We relate t{sub E} to the time t{sub r} it takes a small density perturbation to return to steady state in a relaxed, single mass stellar cusp, t{sub r} {approx_equal} 10t{sub E} {approx_equal} (5/32)Q {sup 2} P{sub h} /N{sub h} log Q, where Q = M {sub .}/M {sub *} is the MBH to star mass ratio, and the orbital period P{sub h} and star number N{sub h} are evaluated at the energy scale of the MBH's sphere of influence, E{sub h} = {sigma}{sup 2} {sub {infinity}}, where {sigma}{sub {infinity}} is the velocity dispersion at infinity. The observed M {sub .}/{sigma}{sub {infinity}} correlation then implies that passively evolving stellar cusps around lower-mass MBHs (M {sub .} {approx}< 10{sup 7} M {sub Sun }) should be dynamically relaxed by the Hubble time. We briefly consider the implications of anomalous diffusion for stars near the Galactic MBH.

  12. Discovery of a bright quasar without a massive host galaxy.

    PubMed

    Magain, Pierre; Letawe, Géraldine; Courbin, Frédéric; Jablonka, Pascale; Jahnke, Knud; Meylan, Georges; Wisotzki, Lutz

    2005-09-15

    A quasar is thought to be powered by the infall of matter onto a supermassive black hole at the centre of a massive galaxy. Because the optical luminosity of quasars exceeds that of their host galaxy, disentangling the two components can be difficult. This led in the 1990s to the controversial claim of the discovery of 'naked' quasars. Since then, the connection between quasars and galaxies has been well established. Here we report the discovery of a quasar lying at the edge of a gas cloud, whose size is comparable to that of a small galaxy, but whose spectrum shows no evidence for stars. The gas in the cloud is excited by the quasar itself. If a host galaxy is present, it is at least six times fainter than would normally be expected for such a bright quasar. The quasar is interacting dynamically with a neighbouring galaxy, whose gas might be feeding the black hole.

  13. Early assembly of the most massive galaxies.

    PubMed

    Collins, Chris A; Stott, John P; Hilton, Matt; Kay, Scott T; Stanford, S Adam; Davidson, Michael; Hosmer, Mark; Hoyle, Ben; Liddle, Andrew; Lloyd-Davies, Ed; Mann, Robert G; Mehrtens, Nicola; Miller, Christopher J; Nichol, Robert C; Romer, A Kathy; Sahlén, Martin; Viana, Pedro T P; West, Michael J

    2009-04-02

    The current consensus is that galaxies begin as small density fluctuations in the early Universe and grow by in situ star formation and hierarchical merging. Stars begin to form relatively quickly in sub-galactic-sized building blocks called haloes which are subsequently assembled into galaxies. However, exactly when this assembly takes place is a matter of some debate. Here we report that the stellar masses of brightest cluster galaxies, which are the most luminous objects emitting stellar light, some 9 billion years ago are not significantly different from their stellar masses today. Brightest cluster galaxies are almost fully assembled 4-5 billion years after the Big Bang, having grown to more than 90 per cent of their final stellar mass by this time. Our data conflict with the most recent galaxy formation models based on the largest simulations of dark-matter halo development. These models predict protracted formation of brightest cluster galaxies over a Hubble time, with only 22 per cent of the stellar mass assembled at the epoch probed by our sample. Our findings suggest a new picture in which brightest cluster galaxies experience an early period of rapid growth rather than prolonged hierarchical assembly.

  14. Non-thermal emission and dynamical state of massive galaxy clusters from CLASH sample

    NASA Astrophysics Data System (ADS)

    Pandey-Pommier, M.; Richard, J.; Combes, F.; Edge, A.; Guiderdoni, B.; Narasimha, D.; Bagchi, J.; Jacob, J.

    2016-12-01

    Massive galaxy clusters are the most violent large scale structures undergoing merger events in the Universe. Based upon their morphological properties in X-rays, they are classified as un-relaxed and relaxed clusters and often host (a fraction of them) different types of non-thermal radio emitting components, viz., 'haloes', 'mini-haloes', 'relics' and 'phoenix' within their Intra Cluster Medium (ICM). The radio haloes show steep (α = -1.2) and ultra steep (α < -1.5) spectral properties at low radio frequencies, giving important insights on the merger (pre or post) state of the cluster. Ultra steep spectrum radio halo emissions are rare and expected to be the dominating population to be discovered via LOFAR and SKA in the future. Further, the distribution of matter (morphological information), alignment of hot X-ray emitting gas from the ICM with the total mass (dark + baryonic matter) and the bright cluster galaxy (BCG) is generally used to study the dynamical state of the cluster. We present here a multi wavelength study on 14 massive clusters from the CLASH survey and show the correlation between the state of their merger in X-ray and spectral properties (1.4 GHz - 150 MHz) at radio wavelengths. Using the optical data we also discuss about the gas-mass alignment, in order to understand the interplay between dark and baryonic matter in massive galaxy clusters.

  15. The Local Dwarf GALAXIES:BUILDING Blocks of Massive Ones? I.THE Fornax Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Nykytyuk, T. V.

    A chemical evolution of the Local Group dwarf galaxy Fornax is considered in the framework of the merger scenario. We suppose a galactic stellar halo to be formed as separate fragments which then merge; thus, we can calculate the set of such the fragments to reproduce the observed metallicity distribution function of a galaxy. Accordingly, if dwarf galaxies were such the systems, which, once merged, have formed massive galaxies, we need to obtain only one fragment to reproduce the observed metallicity distribution function of a dwarf galaxy. To test this assumption, the stellar metallicity distribution functions of Fornax was calculated in the framework of the merger scenario. The more than one fragment was obtained for galaxy under consideration; thus, it is unlikely the systems similar to Fornax to be building blocks of massive galaxies.

  16. Ultra Massive Passive Galaxies at z~1.7

    NASA Astrophysics Data System (ADS)

    Arcila-Osejo, Liz; Sawicki, Marcin; Golob, Anneya; Arnouts, Stephane; Moutard, Thibaud

    At redshift z~1.7 the Universe was at the peak of its star-formation activity. It is thus a puzzle why some galaxies, many of them very massive (M* >= 1011 M⊙), had already chosen to stop forming stars. These ultra-massive galaxies, guaranteed to be the central galaxies of their host dark matter halos, must have attained very high rates of star formation to assemble their stellar masses in such a short amount of time. Using the largest (to date) K-selected gzK s survey of passive galaxies (in an effective area of ~ 27.5 deg2) we study the demographics of these dead monsters, hoping to help understand the quenching mechanism that shut them down.

  17. Do massive black holes reside in elliptical galaxies?

    NASA Technical Reports Server (NTRS)

    Fabian, A. C.; Canizares, C. R.

    1988-01-01

    The accretion by a central black hole of the hot interstellar medium in an elliptical galaxy is investigated, and the minimum expected luminosity and manner of its emission is estimated. It is not obviously detected at any wavelength. The problem of 'starving the monster', if indeed there is a monster, is raised. The simplest conclusion from the evidence is that most bright elliptical galaxies do not contain massive black holes.

  18. Massive Star Clusters in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Larsen, Søren S.

    2017-03-01

    Dwarf galaxies can have very high globular cluster specific frequencies, and the GCs are in general significantly more metal-poor than the bulk of the field stars. In some dwarfs, such as Fornax, WLM, and IKN, the fraction of metal-poor stars that belong to GCs can be as high as 20%-25%, an order of magnitude higher than the 1%-2% typical of GCs in halos of larger galaxies. Given that chemical abundance anomalies appear to be present also in GCs in dwarf galaxies, this implies severe difficulties for self-enrichment scenarios that require GCs to have lost a large fraction of their initial masses. More generally, the number of metal-poor field stars in these galaxies is today less than what would originally have been present in the form of low-mass clusters if the initial cluster mass function was a power-law extending down to low masses. This may imply that the initial GC mass function in these dwarf galaxies was significantly more top-heavy than typically observed in present-day star forming environments.

  19. Structure and Formation of Massive Galaxies with Old Stellar Populations at z=1.5

    NASA Astrophysics Data System (ADS)

    McGrath, Elizabeth J.; Stockton, A.

    2006-12-01

    Observational evidence has been mounting over the past decade that at least some luminous ( 2 L*) galaxies at high redshift have formed nearly all of their stars within the first billion years after the big bang. These are examples of the first major episodes of star formation in the universe and provide insights into the formation of the earliest massive galaxies. We have examined in detail the morphologies and stellar populations of seven z=1.5 passively evolving galaxies using high resolution HST NICMOS and ACS imaging data as well as medium resolution Keck spectroscopy. Almost all of these galaxies appear to be relaxed systems, with smooth morphologies at both rest-frame UV and visible wavelengths. Furthermore, spectral synthesis modeling favors a single burst of star formation more than 2 Gyr before the observed epoch. We note, however, that the prevalence of old stellar populations does not necessarily correlate with early-type morphologies, as the light profiles for several of these galaxies appear to be dominated by massive exponential disks. This evidence for massive old disks, along with the uniformity of stellar age across the disk, suggests formation by a mechanism better described as a form of monolithic collapse than as a hierarchical merger. There is at least one case, however, that appears to be undergoing a "dry merger", which may be an example of the process that converts these unusual galaxies into the familiar spheroids that dominate galaxies comprising old stellar populations at the present epoch. We acknowledge our collaborators in the HST observations, Gabriela Canalizo, Masanori Iye, and Toshinori Maihara. This research was supported by NSF grant AST03-07335 and HST grant GO-10418.01-A.

  20. Linking the spin evolution of massive black holes to galaxy kinematics

    SciTech Connect

    Sesana, A.; Barausse, E.; Dotti, M.; Rossi, E. M. E-mail: barausse@iap.fr E-mail: emr@strw.leidenuniv.nl

    2014-10-20

    We present the results of a semianalytical model that evolves the masses and spins of massive black holes together with the properties of their host galaxies across the cosmic history. As a consistency check, our model broadly reproduces a number of observations, e.g., the cosmic star formation history; the black hole mass, luminosity, and galaxy mass functions at low redshift; the black hole-bulge mass relation; and the morphological distribution at low redshift. For the first time in a semianalytical investigation, we relax the simplifying assumptions of perfect coherency or perfect isotropy of the gas fueling the black holes. The dynamics of gas is instead linked to the morphological properties of the host galaxies, resulting in different spin distributions for black holes hosted in different galaxy types. We compare our results with the observed sample of spin measurements obtained through broad Kα iron line fitting. The observational data disfavor both accretion along a fixed direction and isotropic fueling. Conversely, when the properties of the accretion flow are anchored to the kinematics of the host galaxy, we obtain a good match between theoretical expectations and observations. A mixture of coherent accretion and phases of activity in which the gas dynamics is similar to that of the stars in bulges (i.e., with a significant velocity dispersion superimposed to a net rotation) best describes the data, adding further evidence in support of the coevolution of massive black holes and their hosts.

  1. A Study of Massive and Evolved Galaxies at High Redshift

    NASA Astrophysics Data System (ADS)

    Nayyeri, H.; Mobasher, B.; Hemmati, S.; De Barros, S.; Ferguson, H. C.; Wiklind, T.; Dahlen, T.; Dickinson, M.; Giavalisco, M.; Fontana, A.; Ashby, M.; Barro, G.; Guo, Y.; Hathi, N. P.; Kassin, S.; Koekemoer, A.; Willner, S.; Dunlop, J. S.; Paris, D.; Targett, T. A.

    2014-10-01

    We use data taken as part of Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) observations of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) to identify massive and evolved galaxies at 3 < z < 4.5. This is performed using the strength of the Balmer break feature at rest-frame 3648 Å, which is a diagnostic of the age of the stellar population in galaxies. Using the WFC3 H-band-selected catalog for the CANDELS GOODS-S field and deep multi-waveband photometry from optical (HST) to mid-infrared (Spitzer) wavelengths, we identify a population of old and evolved post-starburst galaxies based on the strength of their Balmer breaks (Balmer break galaxies, BBGs). The galaxies are also selected to be bright in rest-frame near-IR wavelengths and hence massive. We identify a total of 16 BBGs. Fitting the spectral energy distribution of the BBGs shows that the candidate galaxies have average estimated ages of ~800 Myr and average stellar masses of ~5 × 1010 M ⊙, consistent with being old and massive systems. Two of our BBG candidates are also identified by the criteria that are sensitive to star-forming galaxies (Lyman break galaxy selection). We find a number density of ~3.2 × 10-5 Mpc-3 for the BBGs, corresponding to a mass density of ~2.0 × 106 M ⊙ Mpc-3 in the redshift range covering the survey. Given the old age and the passive evolution, it is argued that some of these objects formed the bulk of their mass only a few hundred million years after the big bang.

  2. A study of massive and evolved galaxies at high redshift

    SciTech Connect

    Nayyeri, H.; Mobasher, B.; Hemmati, S.; De Barros, S.; Ferguson, H. C.; Wiklind, T.; Dahlen, T.; Kassin, S.; Koekemoer, A.; Dickinson, M.; Giavalisco, M.; Fontana, A.; Paris, D.; Ashby, M.; Willner, S.; Barro, G.; Guo, Y.; Hathi, N. P.; Dunlop, J. S.; Targett, T. A.

    2014-10-10

    We use data taken as part of Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) observations of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) to identify massive and evolved galaxies at 3 < z < 4.5. This is performed using the strength of the Balmer break feature at rest-frame 3648 Å, which is a diagnostic of the age of the stellar population in galaxies. Using the WFC3 H-band-selected catalog for the CANDELS GOODS-S field and deep multi-waveband photometry from optical (HST) to mid-infrared (Spitzer) wavelengths, we identify a population of old and evolved post-starburst galaxies based on the strength of their Balmer breaks (Balmer break galaxies, BBGs). The galaxies are also selected to be bright in rest-frame near-IR wavelengths and hence massive. We identify a total of 16 BBGs. Fitting the spectral energy distribution of the BBGs shows that the candidate galaxies have average estimated ages of ∼800 Myr and average stellar masses of ∼5 × 10{sup 10} M {sub ☉}, consistent with being old and massive systems. Two of our BBG candidates are also identified by the criteria that are sensitive to star-forming galaxies (Lyman break galaxy selection). We find a number density of ∼3.2 × 10{sup –5} Mpc{sup –3} for the BBGs, corresponding to a mass density of ∼2.0 × 10{sup 6} M {sub ☉} Mpc{sup –3} in the redshift range covering the survey. Given the old age and the passive evolution, it is argued that some of these objects formed the bulk of their mass only a few hundred million years after the big bang.

  3. Galaxy Bulges and Their Massive Black Holes: A Review

    NASA Astrophysics Data System (ADS)

    Graham, Alister W.

    With references to both key and often forgotten pioneering works, this article starts by presenting a review into how we came to believe in the existence of massive black holes at the centers of galaxies. It then presents the historical development of the near-linear (black hole)-(host spheroid) mass relation, before explaining why this has recently been dramatically revised. Past disagreement over the slope of the (black hole)-(velocity dispersion) relation is also explained, and the discovery of sub-structure within the (black hole)-(velocity dispersion) diagram is discussed. As the search for the fundamental connection between massive black holes and their host galaxies continues, the competing array of additional black hole mass scaling relations for samples of predominantly inactive galaxies are presented.

  4. Stellar dynamics around a massive black hole - II. Resonant relaxation

    NASA Astrophysics Data System (ADS)

    Sridhar, S.; Touma, Jihad R.

    2016-06-01

    We present a first-principles theory of resonant relaxation (RR) of a low-mass stellar system orbiting a more massive black hole (MBH). We first extend the kinetic theory of Gilbert to include the Keplerian field of a black hole of mass M•. Specializing to a Keplerian stellar system of mass M ≪ M•, we use the orbit-averaging method of Sridhar & Touma to derive a kinetic equation for RR. This describes the collisional evolution of a system of N ≫ 1 Gaussian rings in a reduced 5-dim space, under the combined actions of self-gravity, 1 post-Newtonian (PN) and 1.5 PN relativistic effects of the MBH and an arbitrary external potential. In general geometries, RR is driven by both apsidal and nodal resonances, so the distinction between scalar RR and vector RR disappears. The system passes through a sequence of quasi-steady secular collisionless equilibria, driven by irreversible two-ring correlations that accrue through gravitational interactions, both direct and collective. This correlation function is related to a `wake function', which is the linear response of the system to the perturbation of a chosen ring. The wake function is easier to appreciate, and satisfies a simpler equation, than the correlation function. We discuss general implications for the interplay of secular dynamics and non-equilibrium statistical mechanics in the evolution of Keplerian stellar systems towards secular thermodynamic equilibria, and set the stage for applications to the RR of axisymmetric discs in Paper III.

  5. Infrared Color Selection of Massive Galaxies at z > 3

    NASA Astrophysics Data System (ADS)

    Wang, T.; Elbaz, D.; Schreiber, C.; Pannella, M.; Shu, X.; Willner, S. P.; Ashby, M. L. N.; Huang, J.-S.; Fontana, A.; Dekel, A.; Daddi, E.; Ferguson, H. C.; Dunlop, J.; Ciesla, L.; Koekemoer, A. M.; Giavalisco, M.; Boutsia, K.; Finkelstein, S.; Juneau, S.; Barro, G.; Koo, D. C.; Michałowski, M. J.; Orellana, G.; Lu, Y.; Castellano, M.; Bourne, N.; Buitrago, F.; Santini, P.; Faber, S. M.; Hathi, N.; Lucas, R. A.; Pérez-González, P. G.

    2016-01-01

    We introduce a new color selection technique to identify high-redshift, massive galaxies that are systematically missed by Lyman-break selection. The new selection is based on the H160 (H) and Infrared Array Camera (IRAC) 4.5 μm bands, specifically H-[4.5]\\gt 2.25 mag. These galaxies, called “HIEROs,” include two major populations that can be separated with an additional J - H color. The populations are massive and dusty star-forming galaxies at z\\gt 3 ({JH}-{blue}) and extremely dusty galaxies at z≲ 3 ({JH}-{red}). The 350 arcmin2 of the GOODS-North and GOODS-South fields with the deepest Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) near-infrared and IRAC data contain as many as 285 HIEROs down to [4.5]\\lt 24 mag. Inclusion of the most extreme HIEROs, not even detected in the H band, makes this selection particularly complete for the identification of massive high-redshift galaxies. We focus here primarily on {JH}-{blue} (z\\gt 3) HIEROs, which have a median photometric redshift < z> ˜ 4.4 and stellar mass {M}*˜ {10}10.6 {M}⊙ and are much fainter in the rest-frame UV than similarly massive Lyman-break galaxies (LBGs). Their star formation rates (SFRs), derived from their stacked infrared spectral energy distributions (SEDs), reach ˜240 {M}⊙ yr-1, leading to a specific SFR, {{sSFR}}\\equiv {{SFR}}/{M}*˜ 4.2 Gyr-1, suggesting that the sSFRs for massive galaxies continue to grow at z\\gt 2 but at a lower growth rate than from z = 0 to z = 2. With a median half-light radius of 2 kpc, including ˜ 20% as compact as quiescent (QS) galaxies at similar redshifts, {JH}-{blue} HIEROs represent perfect star-forming progenitors of the most massive ({M}*≳ {10}11.2 {M}⊙ ) compact QS galaxies at z˜ 3 and have the right number density. HIEROs make up ˜ 60% of all galaxies with {M}*\\gt {10}10.5 {M}⊙ identified at z\\gt 3 from their photometric redshifts. This is five times more than LBGs with nearly no overlap between the two populations

  6. Formation of massive clouds and dwarf galaxies during tidal encounters

    NASA Technical Reports Server (NTRS)

    Kaufman, Michele; Elmegreen, Bruce G.; Thomasson, Magnus; Elmegreen, Debra M.

    1993-01-01

    Gerola et al. (1983) propose that isolated dwarf galaxies can form during galaxy interactions. As evidence of this process, Mirabel et al. (1991) find 10(exp 9) solar mass clouds and star formation complexes at the outer ends of the tidal arms in the Antennae and Superantennae galaxies. We describe observations of HI clouds with mass greater than 10(exp 8) solar mass in the interacting galaxy pair IC 2163/NGC 2207. This pair is important because we believe it represents an early stage in the formation of giant clouds during an encounter. We use a gravitational instability model to explain why the observed clouds are so massive and discuss a two-dimensional N-body simulation of an encounter that produces giant clouds.

  7. BRIGHT Lights, BIG City: Massive Galaxies, Giant Ly-A Nebulae, and Proto-Clusters

    SciTech Connect

    van Breugel, W; Reuland, M; de Vries, W; Stanford, A; Dey, A; Kurk, J; Venemans, B; Rottgering, H; Miley, G; De Breuck, C; Dopita, M; Sutherland, R; Bland-Hawthorn, J

    2002-08-01

    High redshift radio galaxies are great cosmological tools for pinpointing the most massive objects in the early Universe: massive forming galaxies, active super-massive black holes and proto-clusters. They report on deep narrow-band imaging and spectroscopic observations of several z > 2 radio galaxy fields to investigate the nature of giant Ly-{alpha} nebulae centered on the galaxies and to search for over-dense regions around them. They discuss the possible implications for our understanding of the formation and evolution of massive galaxies and galaxy clusters.

  8. Photometric Properties of the Most Massive High-Redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Robertson, Brant; Li, Yuexing; Cox, Thomas J.; Hernquist, Lars; Hopkins, Philip F.

    2007-09-01

    We calculate the observable properties of the most massive high-redshift galaxies in the hierarchical formation scenario where stellar spheroid and supermassive black hole growth are fueled by gas-rich mergers. Combining high-resolution hydrodynamical simulations of the hierarchical formation of a z~6 quasar, stellar population synthesis models, template active galactic nucleus (AGN) spectra, prescriptions for interstellar and intergalactic absorption, and the response of modern telescopes, the photometric evolution of galaxies destined to host z~6 quasars is modeled at redshifts z~4-14. These massive galaxies, with enormous stellar masses of M*~1011.5-1012 Msolar and star formation rates of SFR~103-104 Msolar yr-1 at z>~7, satisfy a variety of photometric selection criteria based on Lyman break techniques, including V-band dropouts at z>~5, i-band dropouts at z>~6, and z-band dropouts at z>~7. The observability of the most massive high-redshift galaxies is assessed and compared with a wide range of existing and proposed photometric surveys, including the Sloan Digital Sky Survey (SDSS), Great Observatories Origins Deep Survey (GOODS)/Hubble Ultra Deep Field (HUDF), National Optical Astronomy Observatory Deep Wide-Field Survey (NDWFS), UKIRT Infared Deep Sky Survey (UKIDSS), Infrared Array Camera (IRAC) Shallow Survey, Ultradeep Visible and Infrared Survey Telescope for Astronomy (VISTA), Dark Universe Explorer (DUNE), Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), Large Synoptic Survey Telescope (LSST), and Supernova/Acceleration Probe (SNAP). Massive stellar spheroids descended from z~6 quasars will likely be detected at z~4 by existing surveys, but owing to their low number densities the discovery of quasar progenitor galaxies at z>7 will likely require future surveys of large portions of the sky (>~0.5%) at wavelengths λ>~1 μm. The detection of rare, starbursting, massive galaxies at redshifts z>~6 would provide support for the

  9. On stars, galaxies and black holes in massive bigravity

    SciTech Connect

    Enander, Jonas; Mörtsell, Edvard E-mail: edvard@fysik.su.se

    2015-11-01

    In this paper we study the phenomenology of stars and galaxies in massive bigravity. We give parameter conditions for the existence of viable star solutions when the radius of the star is much smaller than the Compton wavelength of the graviton. If these parameter conditions are not met, we constrain the ratio between the coupling constants of the two metrics, in order to give viable conditions for e.g. neutron stars. For galaxies, we put constraints on both the Compton wavelength of the graviton and the conformal factor and coupling constants of the two metrics. The relationship between black holes and stars, and whether the former can be formed from the latter, is discussed. We argue that the different asymptotic structure of stars and black holes makes it unlikely that black holes form from the gravitational collapse of stars in massive bigravity.

  10. THE MASSIVE SATELLITE POPULATION OF MILKY-WAY-SIZED GALAXIES

    SciTech Connect

    Rodriguez-Puebla, Aldo; Avila-Reese, Vladimir; Drory, Niv

    2013-08-20

    Several occupational distributions for satellite galaxies more massive than m{sub *} Almost-Equal-To 4 Multiplication-Sign 10{sup 7} M{sub Sun} around Milky-Way (MW)-sized hosts are presented and used to predict the internal dynamics of these satellites as a function of m{sub *}. For the analysis, a large galaxy group mock catalog is constructed on the basis of (sub)halo-to-stellar mass relations fully constrained with currently available observations, namely the galaxy stellar mass function decomposed into centrals and satellites, and the two-point correlation functions at different masses. We find that 6.6% of MW-sized galaxies host two satellites in the mass range of the Small and Large Magellanic Clouds (SMC and LMC, respectively). The probabilities of the MW-sized galaxies having one satellite equal to or larger than the LMC, two satellites equal to or larger than the SMC, or three satellites equal to or larger than Sagittarius (Sgr) are Almost-Equal-To 0.26, 0.14, and 0.14, respectively. The cumulative satellite mass function of the MW, N{sub s} ({>=}m{sub *}) , down to the mass of the Fornax dwarf is within the 1{sigma} distribution of all the MW-sized galaxies. We find that MW-sized hosts with three satellites more massive than Sgr (as the MW) are among the most common cases. However, the most and second most massive satellites in these systems are smaller than the LMC and SMC by roughly 0.7 and 0.8 dex, respectively. We conclude that the distribution N{sub s} ({>=}m{sub *}) for MW-sized galaxies is quite broad, the particular case of the MW being of low frequency but not an outlier. The halo mass of MW-sized galaxies correlates only weakly with N{sub s} ({>=}m{sub *}). Then, it is not possible to accurately determine the MW halo mass by means of its N{sub s} ({>=}m{sub *}); from our catalog, we constrain a lower limit of 1.38 Multiplication-Sign 10{sup 12} M{sub Sun} at the 1{sigma} level. Our analysis strongly suggests that the abundance of massive

  11. A search for the most massive galaxies: double trouble?

    SciTech Connect

    Bernardi, Mariangela; Sheth, R.K.; Nichol, R.C.; Miller, C.J.; Schlegel, D.; Frieman, J.; Schneider, D.P.; Subbarao, M.; York, D.G.; Brinkmann, J.; /Apache Point Observ.

    2005-10-01

    We describe the results of a search for galaxies with large ({approx}> 350 kms{sup -1}) velocity dispersions. The largest systems we have found appear to be the extremes of the early-type galaxy population: compared to other galaxies with similar luminosities, they have the largest velocity dispersions and the smallest sizes. However, they are not distant outliers from the Fundamental Plane and mass-to-light scaling relations defined by the bulk of the early-type galaxy population. They may host the most massive black holes in the Universe, and their abundance and properties can be used to constrain galaxy formation models. Clear outliers from the scaling relations tend to be objects in superposition (angular separations smaller than 1 arcsec), evidence for which comes sometimes from the spectra, sometimes from the images, and sometimes from both. The statistical properties of the superposed pairs, e.g., the distribution of pair separations and velocity dispersions, can be used to provide useful information about the expected distribution of image multiplicities, separations and flux ratios due to gravitational lensing by multiple lenses, and may also constrain models of their interaction rates.

  12. Radioactive 26Al from massive stars in the Galaxy.

    PubMed

    Diehl, Roland; Halloin, Hubert; Kretschmer, Karsten; Lichti, Giselher G; Schönfelder, Volker; Strong, Andrew W; von Kienlin, Andreas; Wang, Wei; Jean, Pierre; Knödlseder, Jürgen; Roques, Jean-Pierre; Weidenspointner, Georg; Schanne, Stephane; Hartmann, Dieter H; Winkler, Christoph; Wunderer, Cornelia

    2006-01-05

    Gamma-rays from radioactive 26Al (half-life approximately 7.2 x 10(5) years) provide a 'snapshot' view of continuing nucleosynthesis in the Galaxy. The Galaxy is relatively transparent to such gamma-rays, and emission has been found concentrated along its plane. This led to the conclusion that massive stars throughout the Galaxy dominate the production of 26Al. On the other hand, meteoritic data show evidence for locally produced 26Al, perhaps from spallation reactions in the protosolar disk. Furthermore, prominent gamma-ray emission from the Cygnus region suggests that a substantial fraction of Galactic 26Al could originate in localized star-forming regions. Here we report high spectral resolution measurements of 26Al emission at 1808.65 keV, which demonstrate that the 26Al source regions corotate with the Galaxy, supporting its Galaxy-wide origin. We determine a present-day equilibrium mass of 2.8 (+/- 0.8) solar masses of 26Al. We use this to determine that the frequency of core collapse (that is, type Ib/c and type II) supernovae is 1.9 (+/- 1.1) events per century.

  13. Cosmology and astrophysics from relaxed galaxy clusters - III. Thermodynamic profiles and scaling relations

    NASA Astrophysics Data System (ADS)

    Mantz, A. B.; Allen, S. W.; Morris, R. G.; Schmidt, R. W.

    2016-03-01

    This is the third in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot (i.e. massive) in Papers I and II of this series. Here we consider the thermodynamics of the intracluster medium, in particular the profiles of density, temperature and related quantities, as well as integrated measurements of gas mass, average temperature, total luminosity and centre-excluded luminosity. We fit power-law scaling relations of each of these quantities as a function of redshift and cluster mass, which can be measured precisely and with minimal bias for these relaxed clusters using hydrostatic arguments. For the thermodynamic profiles, we jointly model the density and temperature and their intrinsic scatter as a function of radius, thus also capturing the behaviour of the gas pressure and entropy. For the integrated quantities, we also jointly fit a multidimensional intrinsic covariance. Our results reinforce the view that simple hydrodynamical models provide a good description of relaxed clusters outside their centres, but that additional heating and cooling processes are important in the inner regions (radii r ≲ 0.5 r2500 ≈ 0.15 r500). The thermodynamic profiles remain regular, with small intrinsic scatter, down to the smallest radii where deprojection is straightforward (˜20 kpc); within this radius, even the most relaxed systems show clear departures from spherical symmetry. Our results suggest that heating and cooling are continuously regulated in a tight feedback loop, allowing the cluster atmosphere to remain stratified on these scales.

  14. Most Massive Spiral Galaxy Known in the Universe

    NASA Astrophysics Data System (ADS)

    2000-12-01

    The VLT Observes Rapid Motion in Distant Object Summary The most massive spiral galaxy known so far in the Universe has been discovered by a team of astronomers from Garching, Padova, Leiden, ESO and London [1]. They base their conclusion on recent observations with ISAAC , an infrared-sensitive, multi-mode instrument on ESO's Very Large Telescope at the Paranal Observatory. This galaxy has been designated ISOHDFS 27 and is located at a distance of approx. 6 billion light-years (the redshift is 0.58). Its measured mass is more than 1000 billion times that of the Sun [2]. It is thus about four times more massive than our own galaxy, the Milky Way, and twice as heavy as the heaviest spiral galaxy known so far. The determination of the mass of ISOHDFS 27 is based on a unique measurement of the motions of its stars and nebulae around the center. The faster the motion is, the greater is the mass. It is, in essence, the same method that allows determining the mass of the Earth from the orbital speed and distance of the Moon. This is the first time a "rotation curve" has been observed in such a distant galaxy by means of infrared observations, allowing a very detailed dynamical study. Other observations by the team concern a pair of distant, interacting galaxies that were also found to possess comparably high masses. They also have observations of a third galaxy at a distance of about 10 billion light-years, with a mass that approaches that of ISOHDFS 27 . The new result has important cosmological implications, as it demonstrates that very heavy structures had already been formed in the Universe at a comparatively early epoch . PR Photo 33a/00 : ISOHDFS 27 , the heaviest spiral galaxy known. PR Photo 33b/00 : The "raw" ISAAC spectrum of ISOHDFS 27 . PR Photo 33c/00 : H-alpha profile of ISOHDFS 27 . Star formation in young galaxies It is of fundamental importance to current cosmological studies to understand how stars evolve within galaxies and how the galaxies themselves

  15. Stellar haloes in massive early-type galaxies

    NASA Astrophysics Data System (ADS)

    Buitrago, F.

    2017-03-01

    The Hubble Ultra Deep Field (HUDF) opens up an unique window to witness galaxy assembly at all cosmic distances. Thanks to its extraordinary depth, it is a privileged tool to beat the cosmological dimming, which affects any extragalactic observations and has a very strong dependence with redshift (1 +z)^4. In particular, massive (M_{stellar}>5 × 10^{10} M_⊙) Early Type Galaxies (ETGs) are the most interesting candidates for these studies, as they must grow in an inside-out fashion developing an extended stellar envelope/halo that accounts for their remarkable size evolution (˜5 times larger in the nearby Universe than at z=2-3). To this end we have analysed the 6 most massive ETGs at z <1 in the HUDF12. Because of the careful data reduction and the exhaustive treatment of the Point Spread Function (PSF), we are able to trace the galaxy surface brightness profiles up to the same levels as in the local Universe but this time at = 0.65 (31 mag arcsec^{-2} in all 8 HST bands, ˜ 29 mag arcsec^{-2} restframe or beyond 25 effective radii). This fact enables us to investigate the galactic outskirts or stellar haloes at a previously unexplored era, characterising their light and mass profiles, colors and for the first time the amount of mass in ongoing mergers.

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

    NASA Astrophysics Data System (ADS)

    Casey, Caitlin M.

    2016-06-01

    The universe’s largest galaxy clusters likely built the majority of their massive >1011 M {}⊙ galaxies in simultaneous, short-lived bursts of activity well before virialization. This conclusion is reached based on emerging data sets for z\\gt 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, ˜104 comoving Mpc3 at z\\gt 2, subtending areas of approximately 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 2≲ z≲ 3 proto-clusters from the literature are discussed in detail and are found to contain up to 12 dusty starbursts or luminous AGN galaxies each, a phenomenon that is unlikely to occur by chance even in overdense environments. These are contrasted with three higher-redshift (4≲ z≲ 5.5) dusty star-forming galaxy (DSFG) groups, whose evolutionary fate is less clear. Measurements of DSFGs’ gas depletion times suggest that they are indeed short-lived on ˜100 Myr timescales, and accordingly the probability of finding a structure containing more than 8 such systems is ˜0.2%, unless their “triggering” is correlated on very large spatial scales, ˜10 Mpc across. The volume density of DSFG-rich proto-clusters is found to be comparable to all of the >1015 M {}⊙ galaxy clusters in the nearby universe, which is a factor of five larger than expected in some simulations. Some tension still exists between measurements of the volume density of DSFG-rich proto-clusters and the expectation that they are generated via short-lived episodes, as the latter suggests that only a fraction (\\lt \\tfrac{1}{2}) of all proto-clusters should be rich with DSFGs. However, improved observations of proto

  17. THE UNIFICATION OF POWERFUL QUASARS AND RADIO GALAXIES AND THEIR RELATION TO OTHER MASSIVE GALAXIES

    SciTech Connect

    Podigachoski, Pece; Barthel, Peter; Haas, Martin; Leipski, Christian; Wilkes, Belinda

    2015-06-10

    The unification model for powerful radio galaxies (RGs) and radio-loud quasars postulates that these objects are intrinsically the same but viewed along different angles. Herschel Space Observatory data permit the assessment of that model in the far-infrared spectral window. We analyze photometry from Spitzer and Herschel for the distant 3CR hosts, and find that RGs and quasars have different mid-infrared, but indistinguishable far-infrared colors. Both these properties, the former being orientation dependent and the latter orientation invariant, are in line with expectations from the unification model. Adding powerful radio-quiet active galaxies and typical massive star-forming (SF) galaxies to the analysis, we demonstrate that infrared colors not only provide an orientation indicator, but can also distinguish active from SF galaxies.

  18. Violent Relaxation, Dynamical Instabilities and the Formation of Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Aguilar, L. A.

    1990-11-01

    RESUMEN: El problema de la formaci6n de galaxias elfpticas por medjo de colapso gravitacional sin disipaci6n de energfa es estudiado usando un gran numero de simulaciones numericas. Se muestra que este tipo de colapsos, partiendo de condiciones iniciales frfas donde la energfa cinetica inicial representa s6lo un 5%, 0 , de a potencial inicial, produce sistemas relajados de forma triaxial muy similares a las galaxias elfpticas reales en sus formas y perfiles de densidad en proyecci6i . La forina triaxial resulta de la acci6n de una inestabilidad dinamica que aparece en sistemas 'inicos dominados por movimientos radiales, mientras que el perfil de densidad final Cs debido al llamado relajamiento violento que tiende a producir una distribuci6n en espacio fase unica. Estos dos fen6menos tienden a borrar los detalles particulares sobre las condiciones iniciales y dan lugar a una evoluci6n convergente hacia sistemas realistas, esto innecesario el uso de condiciones iniciales especiales (excepto por Ia condici6i de que estas deben ser frfas). Las condiciones iniciales frfas producen los movimientos radiales y fluctuaciones de la energfa potencial requeridos por ambos fen6menos. ABSTRACT: The problem of formation of elliptical galaxies via dissipationless collapse is studied using a large set of numerical simulations. It is shown that dissipationless collapses from cold initial conditions, where the total initial kinetic energy is less than 5% ofthe initial potential energy, lead to relaxed triaxial systems ery similar to real elliptical galaxies ii projected shape and density profiles. The triaxial shape is due to the of a dynamical instability that appears on systems dominated by radial orbits, while final density profile is due to violent relaxation that tends to produce a unique distribution iii space. These two phenomena erase memory of the initial prodtice a convergent evolution toward realistic systems, thus making unnecessary use o[special initial conditions (other

  19. Early quenching of massive protocluster galaxies around z = 2.2 radio galaxies

    NASA Astrophysics Data System (ADS)

    Husband, K.; Bremer, M. N.; Stott, J. P.; Murphy, D. N. A.

    2016-10-01

    Radio galaxies are among the most massive galaxies in the high-redshift Universe and are known to often lie in protocluster environments. We have studied the fields of seven z = 2.2 radio galaxies with High Acuity Wide field K-band Imager (HAWK-I) narrow-band and broad-band imaging in order to map out their environment using Hα emitters (HAEs). The results are compared to the blank field HAE survey HiZELS. All of the radio galaxy fields are overdense in HAEs relative to a typical HiZELS field of the same area and four of the seven are richer than all except one of 65 essentially random HiZELS subfields of the same size. The star formation rates of the massive HAEs are lower than those necessary to have formed their stellar population in the preceding Gyr - indicating that these galaxies are likely to have formed the bulk of their stars at higher redshifts, and are starting to quench.

  20. A faint galaxy redshift survey behind massive clusters

    SciTech Connect

    Frye, Brenda Louise

    1999-05-01

    This thesis is concerned with the gravitational lensing effect by massive galaxy clusters. We have explored a new technique for measuring galaxy masses and for detecting high-z galaxies by their optical colors. A redshift survey has been obtained at the Keck for a magnitude limited sample of objects (I<23) behind three clusters, A1689, A2390, and A2218 within a radius of 0.5M pc. For each cluster we see both a clear trend of increasing flux and redshift towards the center. This behavior is the result of image magnifications, such that at fixed redshift one sees further down the luminosity function. The gradient of this magnification is, unlike measurements of image distortion, sensitive to the mass profile, and found to depart strongly from a pure isothermal halo. We have found that V RI color selection can be used effectively as a discriminant for finding high-z galaxies behind clusters and present five 4.1 < z < 5.1 spectra which are of very high quality due to their high mean magnification of ~20, showing strong, visibly-saturated interstellar metal lines in some cases. We have also investigated the radio ring lens PKS 1830-211, locating the source and multiple images and detected molecular absorption at mm wavelengths. Broad molecular absorption of width 1/40kms is found toward the southwest component only, where surprisingly it does not reach the base of the continuum, which implies incomplete coverage of the SW component by molecular gas, despite the small projected size of the source, less than 1/8h pc at the absorption redshift.

  1. Cosmology and astrophysics from relaxed galaxy clusters – V. Consistency with cold dark matter structure formation

    DOE PAGES

    Mantz, A. B.; Allen, S. W.; Morris, R. G.

    2016-07-15

    This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the cold dark matter (CDM) paradigm. In addition, we present constraints on the concentration–mass relation for massive clusters, finding a power-law mass dependence with a slope of κm = –0.16 ± 0.07, in agreement with CDM predictions.more » For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κζ = –0.17 ± 0.26), with an intrinsic scatter of σln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ~50 kpc–1 Mpc), and test for departures from the simple Navarro–Frenk–White (NFW) form, for which the logarithmic slope of the density profile tends to –1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σβ = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σα = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.« less

  2. Cosmology and astrophysics from relaxed galaxy clusters – V. Consistency with cold dark matter structure formation

    SciTech Connect

    Mantz, A. B.; Allen, S. W.; Morris, R. G.

    2016-07-15

    This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the cold dark matter (CDM) paradigm. We present constraints on the concentration–mass relation for massive clusters, finding a power-law mass dependence with a slope of κm = -0.16 ± 0.07, in agreement with CDM predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κζ = -0.17 ± 0.26), with an intrinsic scatter of σln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ~50 kpc–1 Mpc), and test for departures from the simple Navarro–Frenk–White (NFW) form, for which the logarithmic slope of the density profile tends to -1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σβ = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σα = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.

  3. WHAT ARE THE PROGENITORS OF COMPACT, MASSIVE, QUIESCENT GALAXIES AT z = 2.3? THE POPULATION OF MASSIVE GALAXIES AT z > 3 FROM NMBS AND CANDELS

    SciTech Connect

    Stefanon, Mauro; Rudnick, Gregory H.; Marchesini, Danilo; Brammer, Gabriel B.; Whitaker, Katherine E.

    2013-05-01

    Using public data from the NEWFIRM Medium-Band Survey (NMBS) and the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS), we investigate the population of massive galaxies at z > 3. The main aim of this work is to identify the potential progenitors of z {approx} 2 compact, massive, quiescent galaxies (CMQGs), furthering our understanding of the onset and evolution of massive galaxies. Our work is enabled by high-resolution images from CANDELS data and accurate photometric redshifts, stellar masses, and star formation rates (SFRs) from 37-band NMBS photometry. The total number of massive galaxies at z > 3 is consistent with the number of massive, quiescent galaxies (MQGs) at z {approx} 2, implying that the SFRs for all of these galaxies must be much lower by z {approx} 2. We discover four CMQGs at z > 3, pushing back the time for which such galaxies have been observed. However, the volume density for these galaxies is significantly less than that of galaxies at z < 2 with similar masses, SFRs, and sizes, implying that additional CMQGs must be created in the intervening {approx}1 Gyr between z = 3 and z = 2. We find five star-forming galaxies at z {approx} 3 that are compact (R{sub e} < 1.4 kpc) and have stellar mass M{sub *} > 10{sup 10.6} M{sub Sun }; these galaxies are likely to become members of the massive, quiescent, compact galaxy population at z {approx} 2. We evolve the stellar masses and SFRs of each individual z > 3 galaxy adopting five different star formation histories (SFHs) and studying the resulting population of massive galaxies at z = 2.3. We find that declining or truncated SFHs are necessary to match the observed number density of MQGs at z {approx} 2, whereas a constant delayed-exponential SFH would result in a number density significantly smaller than observed. All of our assumed SFHs imply number densities of CMQGs at z {approx} 2 that are consistent with the observed number density. Better agreement with the observed

  4. Molecular gas in the halo fuels the growth of a massive cluster galaxy at high redshift.

    PubMed

    Emonts, B H C; Lehnert, M D; Villar-Martín, M; Norris, R P; Ekers, R D; van Moorsel, G A; Dannerbauer, H; Pentericci, L; Miley, G K; Allison, J R; Sadler, E M; Guillard, P; Carilli, C L; Mao, M Y; Röttgering, H J A; De Breuck, C; Seymour, N; Gullberg, B; Ceverino, D; Jagannathan, P; Vernet, J; Indermuehle, B T

    2016-12-02

    The largest galaxies in the universe reside in galaxy clusters. Using sensitive observations of carbon monoxide, we show that the Spiderweb galaxy-a massive galaxy in a distant protocluster-is forming from a large reservoir of molecular gas. Most of this molecular gas lies between the protocluster galaxies and has low velocity dispersion, indicating that it is part of an enriched intergalactic medium. This may constitute the reservoir of gas that fuels the widespread star formation seen in earlier ultraviolet observations of the Spiderweb galaxy. Our results support the notion that giant galaxies in clusters formed from extended regions of recycled gas at high redshift.

  5. Hot, Massive Stars in the Extremely Metal-Poor Galaxy, I Zw 18

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Malumuth, Eliot M.

    2010-01-01

    The extremely metal-poor galaxy I Zw 18, is the Rosetta Stone for understanding z=7-8 galaxies now being discovered by Hubb|e's Wide Field Camera 3 (HST/WFC3). Using HST/STIS images and recently obtained HST/COS ultraviolet spectra, we derive information about the hot, massive stars in this galaxy including stellar abundances, constraints on the stellar IMF and mass distribution of young clusters containing hot, massive stars.

  6. Early-type galaxies have been the predominant morphological class for massive galaxies since only z ˜ 1

    NASA Astrophysics Data System (ADS)

    Buitrago, Fernando; Trujillo, Ignacio; Conselice, Christopher J.; Häußler, Boris

    2013-01-01

    Present-day massive galaxies are composed mostly of early-type objects. It is unknown whether this was also the case at higher redshifts. In a hierarchical assembling scenario the morphological content of the massive population is expected to change with time from disc-like objects in the early Universe to spheroid-like galaxies at present. In this paper we have probed this theoretical expectation by compiling a large sample of massive (Mstellar ≥ 1011 h- 270 M⊙) galaxies in the redshift interval 0 < z < 3. Our sample of 1082 objects comprises 207 local galaxies selected from Sloan Digital Sky Survey plus 875 objects observed with the Hubble Space Telescope belonging to the Palomar Observatory Wide-field InfraRed/DEEP2 and GOODS NICMOS Survey surveys. 639 of our objects have spectroscopic redshifts. Our morphological classification is performed as close as possible to the optical rest frame according to the photometric bands available in our observations both quantitatively (using the Sérsic index as a morphological proxy) and qualitatively (by visual inspection). Using both techniques we find an enormous change on the dominant morphological class with cosmic time. The fraction of early-type galaxies among the massive galaxy population has changed from ˜20-30 per cent at z ˜ 3 to ˜70 per cent at z = 0. Early-type galaxies have been the predominant morphological class for massive galaxies since only z ˜ 1.

  7. A search for massive compact halo objects in our Galaxy

    NASA Astrophysics Data System (ADS)

    Bennett, D. P.; Alcock, C.; Axelrod, T.; Cook, K.; Park, H.; Griest, K.; Stubbs, C.; Freeman, K.; Peterson, B.; Quinn, P.; Rogers, A.

    1991-04-01

    Massive compact halo objects such as brown dwarfs, Jupiters, and black holes are prime candidates to comprise the dark halo of our galaxy. Our group is currently involved in constructing a dedicated observing system at the Mount Stromlo Observatory in Australia. We will use a refurbished 1.27 meter telescope and an innovative two-color CCD camera with 3.4 x 10 exp 7 pixels to monitor 10 exp 6 - 10 exp 7 stars in the Magellanic Clouds. During the first year of operation (1991-1992), we hope to detect (or rule out) objects in the mass range between 0.001 and 0.1 solar mass, and after five years, we hope to have covered the range 10 exp -6 solar mass - 10 exp 2 solar masses.

  8. Constraints on shear and rotation with massive galaxy clusters

    NASA Astrophysics Data System (ADS)

    Mehrabi, Ahmad; Pace, Francesco; Malekjani, Mohammad; Del Popolo, Antonino

    2017-03-01

    A precise determination of the mass function is an important tool to verify cosmological predictions of the Λ cold dark matter (CDM) model and to infer more precisely the better model describing the evolution of the Universe. Galaxy clusters have been currently used to infer cosmological parameters, in particular the matter density parameter Ωm, the matter power spectrum normalization σ8 and the equation of state parameter wde of the dark energy fluid. In this work, using data on massive galaxy clusters (M > 8 × 1014 h-1 M⊙) in the redshift range 0.05 ≲ z ≲ 0.83, for the first time we put constraints on the parameter α introduced within the formalism of the extended spherical collapse model to quantify deviations from sphericity due to shear and rotation. Since at the moment there is no physical model describing its functional shape, we assume it to be a logarithmic function of the cluster mass. By holding σ8 fixed and restricting our analysis to a ΛCDM model, we find, at 1σ confidence level, Ωm = 0.284 ± 0.0064, h = 0.678 ± 0.017 and β =0.0019^{+0.0008}_{-0.0015}, where β represents the slope of the parameter α. This result translates into a 9 per cent decrement of the number of massive clusters with respect to a standard ΛCDM mass function, but better data are required to better constrain this quantity, since at the 2σ and 3σ confidence level we are only able to infer upper limits.

  9. A large Hα survey of star formation in relaxed and merging galaxy cluster environments at z ∼ 0.15-0.3

    NASA Astrophysics Data System (ADS)

    Stroe, Andra; Sobral, David; Paulino-Afonso, Ana; Alegre, Lara; Calhau, João; Santos, Sergio; van Weeren, Reinout

    2017-03-01

    We present the first results from the largest Hα survey of star formation and active galactic nucleus activity in galaxy clusters. Using nine different narrow-band filters, we select >3000 Hα emitters within 19 clusters and their larger scale environment over a total volume of 1.3 × 105 Mpc3. The sample includes both relaxed and merging clusters, covering the 0.15-0.31 redshift range and spanning from 5 × 1014 to 30 × 1014 M⊙. We find that the Hα luminosity function for merging clusters has a higher characteristic density ϕ* compared to relaxed clusters. ϕ* drops from cluster core to cluster outskirts for both merging and relaxed clusters, with the merging cluster values ∼0.3 dex higher at each projected radius. The characteristic luminosity L* drops over the 0.5-2.0 Mpc distance from the cluster centre for merging clusters and increases for relaxed objects. Among disturbed objects, clusters hosting large-scale shock waves (traced by radio relics) are overdense in Hα emitters compared to those with turbulence in their intracluster medium (traced by radio haloes). We speculate that the increase in star formation activity in disturbed, young, massive galaxy clusters can be triggered by interactions between gas-rich galaxies, shocks and/or the intracluster medium, as well as accretion of filaments and galaxy groups. Our results indicate that disturbed clusters represent vastly different environments for galaxy evolution compared to relaxed clusters or average field environments.

  10. Hunting for missing (massive) stars in the Galaxy

    NASA Astrophysics Data System (ADS)

    Flagey, Nicolas

    2015-08-01

    We discovered over 400 compact (<1’) “bubbles” from visual inspection of the Spitzer/MIPSGAL 24 μm images of the Galactic plane (Carey et al. 2009; Mizuno et al. 2010). At the time of their discovery, only 15% of these MIPSGAL bubbles (MBs) existed in available catalogs, and most of these previously known MB were planetary nebulae. Over the past three years an important observational effort has been made to characterize the nature of more MBs (e.g. Wachter et al. 2010; Gvaramadze et al. 2010; Flagey et al. 2011, 2014; Nowak et al. 2014). The number of identified MBs has now doubled (30% of the 428), and massive stars represent almost half of the known objects. Most of the new identifications have been obtained via optical and near-IR spectroscopic observations of the source detected at the center of the MBs.I will first present the catalog of the MB and the general properties, in terms of morphology, size, and broadband fluxes, of the circumstellar shells. In particular, I will show that far-IR observations from the Herschel Galactic Plane Survey (Molinari et al. 2010) provide a direct measurement of the dust mass ejected by theMB. Then, I will detail some of the follow-up spectroscopic observations obtained to identify the origin of the mid-IR emission and the nature of the unknown objects. In particular, I will focus on: (1) unique Spitzer/IRS observations of 15 MBs that lead to the discovery of several dust poor planetary nebulae with very hot white dwarf, and the characterization of several WR and LBV candidates; (2) ground based (Palomar, IRTF, VLT) near-IR observations of central sources in MB, that revealed a large number of new massive stars, both cool and hot. I will summarize the results of these investigations and others in terms of newly discovered massive stars in our Galaxy.

  11. Detection of Prominent Stellar Disks in the Progenitors of Present-day Massive Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Davari, Roozbeh H.; Ho, Luis C.; Mobasher, Bahram; Canalizo, Gabriela

    2017-02-01

    Massive galaxies at high redshifts (z > 2) show different characteristics from their local counterparts: they are compact and most likely have a disk. In this study, we trace the evolution of local massive galaxies by performing a detailed morphological analysis, namely, fitting single Sérsic profiles and performing bulge+disk decompositions. We analyze ∼250 massive galaxies selected from all CANDELS fields (COSMOS, UDS, EGS, GOODS-South, and GOODS-North). We confirm that both star-forming and quiescent galaxies increase their sizes significantly from z ≈ 2.5 to the present day. The global Sérsic index of quiescent galaxies increases over time (from n ≈ 2.5 to n > 4), while that of star-forming galaxies remains roughly constant (n ≈ 2.5). By decomposing galaxy profiles into bulge+disk components, we find that massive galaxies at high redshift have prominent stellar disks, which are also evident from visual inspection of the images. By z ≈ 0.5, the majority of the disks disappear and massive quiescent galaxies begin to resemble the local elliptical galaxies. Star-forming galaxies have lower bulge-to-total ratios (B/T) than their quiescent counterparts in each redshift bin. The bulges of star-forming and quiescent galaxies follow different evolutionary histories, while their disks evolve similarly. Based on our morphological analysis and previous cosmological simulations, we argue that major mergers, along with minor mergers, have played a crucial role in the significant increase in size of high-z galaxies and the destruction of their massive and large-scale disks.

  12. A high abundance of massive galaxies 3-6 billion years after the Big Bang.

    PubMed

    Glazebrook, Karl; Abraham, Roberto G; McCarthy, Patrick J; Savaglio, Sandra; Chen, Hsiao-Wen; Crampton, David; Murowinski, Rick; Jørgensen, Inger; Roth, Kathy; Hook, Isobel; Marzke, Ronald O; Carlberg, R G

    2004-07-08

    Hierarchical galaxy formation is the model whereby massive galaxies form from an assembly of smaller units. The most massive objects therefore form last. The model succeeds in describing the clustering of galaxies, but the evolutionary history of massive galaxies, as revealed by their visible stars and gas, is not accurately predicted. Near-infrared observations (which allow us to measure the stellar masses of high-redshift galaxies) and deep multi-colour images indicate that a large fraction of the stars in massive galaxies form in the first 5 Gyr (refs 4-7), but uncertainties remain owing to the lack of spectra to confirm the redshifts (which are estimated from the colours) and the role of obscuration by dust. Here we report the results of a spectroscopic redshift survey that probes the most massive and quiescent galaxies back to an era only 3 Gyr after the Big Bang. We find that at least two-thirds of massive galaxies have appeared since this era, but also that a significant fraction of them are already in place in the early Universe.

  13. Two new confirmed massive relic galaxies: red nuggets in the present-day Universe

    NASA Astrophysics Data System (ADS)

    Ferré-Mateu, Anna; Trujillo, Ignacio; Martín-Navarro, Ignacio; Vazdekis, Alexandre; Mezcua, Mar; Balcells, Marc; Domínguez, Lilian

    2017-01-01

    We confirm two new local massive relic galaxies, i.e. untouched survivors of the early universe massive population: Mrk 1216 and PGC 032873. Both show early and peaked formation events within very short timescales (<1 Gyr) and thus old mean mass-weighted ages (˜13 Gyr). Their star formation histories remain virtually unchanged out to several effective radii, even when considering the steeper IMF values inferred out to ˜3 effective radii. Their morphologies, kinematics and density profiles are like those found in the z>2 massive population, setting them apart of the typical z˜0 massive early-type galaxies. We find that there seems to exist a degree of relic that is related on how far into the path to become one of these typical z˜0 massive galaxies the compact relic has undergone. This path is partly dictated by the environment the galaxy lives in. For galaxies in rich environments, such as the previously reported relic galaxy NGC 1277, the most extreme properties (e.g. sizes, short formation timescales, larger super-massive black holes) are expected, while lower density environments will have galaxies with delayed and/or extended star formations, slightly larger sizes and not that extreme black hole masses. The confirmation of 3 relic galaxies up to a distance of 106 Mpc implies a lower limit in the number density of these red nuggets in the local universe of 6× 10-7 Mpc3, which is within the theoretical expectations.

  14. Radio-Mode Feedback in Massive Galaxies at Redshift 0 < z < 1

    NASA Astrophysics Data System (ADS)

    Sadler, Elaine M.; Croom, Scott M.; Ching, John H. Y.; Johnston, Helen M.; Cannon, Russell D.; Mauch, Tom

    2010-05-01

    We have carried out a large observational study of the radio luminosities, stellar populations, and environments of massive galaxies over the redshift range 0 < z < 1. Radio jets powered by an accreting central black hole are common in massive galaxies, and there is a large class of “optically quiet AGN,” with radio emission but no optical/IR signature of black-hole accretion. The central black holes in these galaxies are probably accreting in a radiatively inefficient mode, and our results suggest that “radio-mode feedback” as described by Croton et al. is likely to occur in all masssive early-type galaxies at z < 0.8. While it appears that radio-loud AGN occur episodically in all massive early-type galaxies, we also identify a sub-population of galaxies with powerful radio sources and a prominent younger (~ 108 yr) stellar population that may have undergone recent mergers.

  15. Molecular gas in the halo fuels the growth of a massive cluster galaxy at high redshift

    NASA Astrophysics Data System (ADS)

    Emonts, B. H. C.; Lehnert, M. D.; Villar-Martín, M.; Norris, R. P.; Ekers, R. D.; van Moorsel, G. A.; Dannerbauer, H.; Pentericci, L.; Miley, G. K.; Allison, J. R.; Sadler, E. M.; Guillard, P.; Carilli, C. L.; Mao, M. Y.; Röttgering, H. J. A.; De Breuck, C.; Seymour, N.; Gullberg, B.; Ceverino, D.; Jagannathan, P.; Vernet, J.; Indermuehle, B. T.

    2016-12-01

    The largest galaxies in the universe reside in galaxy clusters. Using sensitive observations of carbon monoxide, we show that the Spiderweb galaxy—a massive galaxy in a distant protocluster—is forming from a large reservoir of molecular gas. Most of this molecular gas lies between the protocluster galaxies and has low velocity dispersion, indicating that it is part of an enriched intergalactic medium. This may constitute the reservoir of gas that fuels the widespread star formation seen in earlier ultraviolet observations of the Spiderweb galaxy. Our results support the notion that giant galaxies in clusters formed from extended regions of recycled gas at high redshift.

  16. Massive Galaxies Are Larger in Dense Environments: Environmental Dependence of Mass–Size Relation of Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Yoon, Yongmin; Im, Myungshin; Kim, Jae-Woo

    2017-01-01

    Under the Λ cold dark matter (ΛCDM) cosmological models, massive galaxies are expected to be larger in denser environments through frequent hierarchical mergers with other galaxies. Yet, observational studies of low-redshift early-type galaxies have shown no such trend, standing as a puzzle to solve during the past decade. We analyzed 73,116 early-type galaxies at 0.1 ≤ z < 0.15, adopting a robust nonparametric size measurement technique and extending the analysis to many massive galaxies. We find for the first time that local early-type galaxies heavier than 1011.2 M⊙ show a clear environmental dependence in mass–size relation, in such a way that galaxies are as much as 20%–40% larger in the densest environments than in underdense environments. Splitting the sample into the brightest cluster galaxies (BCGs) and non-BCGs does not affect the result. This result agrees with the ΛCDM cosmological simulations and suggests that mergers played a significant role in the growth of massive galaxies in dense environments as expected in theory.

  17. Formation des etoiles massives dans les galaxies spirales

    NASA Astrophysics Data System (ADS)

    Lelievre, Mario

    Le but de cette thèse est de décrire la formation des étoiles massives dans les galaxies spirales appartenant à divers types morphologiques. L'imagerie Hα profonde combinée à une robuste méthode d'identification des régions HII ont permis de détecter et de mesurer les propriétés (position, taille, luminosité, taux de formation d'étoiles) de plusieurs régions HII situées dans le disque interne (R < R25) de dix galaxies mais aussi à leur périphérie (R ≥ R 25). De façon générale, la répartition des régions HII ne montre aucune évidence de structure morphologique à R < R25 (bras spiraux, anneau, barre) à moins de limiter l'analyse aux régions HII les plus grosses ou les plus lumineuses. La répartition des régions HII, de même que leur taille et leur luminosité, sont toutefois sujettes à de forts effets de sélection qui dépendent de la distance des galaxies et qu'il faut corriger en ramenant l'échantillon à une résolution spatiale commune. Les fonctions de luminosité montrent que les régions HII les plus brillantes ont tendance à se former dans la portion interne du disque. De plus, l'analyse des pentes révèle une forte corrélation linéaire par rapport au type morphologique. Aucun pic n'est observé dans les fonctions de luminosité à log L-37 qui révèlerait la transition entre les régions HII bornées par l'ionisation et par la densité. Une relation cubique est obtenue entre la taille et la luminosité des régions HII, cette relation variant toutefois de façon significative entre le disque interne et la périphérie d'une même galaxie. La densité et la dynamique du gaz et des étoiles pourraient influencer de façon significative la stabilité des nuages moléculaires face à l'effondrement gravitationnel. D'une part, l'étendue du disque de régions HII pour cinq galaxies de l'échantillon coïncide avec celle de l'hydrogène atomique. D'autre part, en analysant la stabilité des disques galactiques, on conclue

  18. Revealing Massive Black Holes in Dwarf Galaxies with X-rays

    NASA Astrophysics Data System (ADS)

    Reines, A.

    2014-07-01

    Supermassive black holes (BHs) live at the heart of essentially all massive galaxies, power AGN, and are thought to be important agents in the evolution of their hosts. However, the origin of these monster BHs is largely unknown. While direct observations of the first ``seeds" of supermassive BHs in the infant Universe are unobtainable with current telescopes, finding and studying dwarf galaxies hosting massive BHs today can provide valuable constraints on the masses, host galaxies, and formation mechanism of supermassive BH seeds. We have recently completed the first systematic search for AGN in dwarf galaxies using optical spectroscopy, increasing the number of known dwarfs with massive BHs by more than an order of magnitude (Reines et al. 2013). However, this optical search is biased towards BHs radiating at high fractions of their Eddington limit in galaxies with little on-going star formation. Alternative search techniques and diagnostics at other wavelengths are necessary to make further progress. I will discuss our efforts to find and study massive BHs in dwarf galaxies using observations at X-ray wavelengths. These observations are more sensitive to weakly accreting massive BHs and are already beginning to reveal massive BHs hidden at optical wavelengths in star-forming dwarf galaxies.

  19. SATELLITES AROUND MASSIVE GALAXIES SINCE z {approx} 2: CONFRONTING THE MILLENNIUM SIMULATION WITH OBSERVATIONS

    SciTech Connect

    Quilis, Vicent; Trujillo, Ignacio

    2012-06-20

    Minor merging has been postulated as the most likely evolutionary path to produce the increase in size and mass observed in the massive galaxies since z {approx} 2. In this Letter, we directly test this hypothesis, comparing the population of satellites around massive galaxies in cosmological simulations versus the observations. We use state-of-the-art, publically available, Millennium I and II simulations, and the associated semi-analytical galaxy catalogs to explore the time evolution of the fraction of massive galaxies that have satellites, the number of satellites per galaxy, the projected distance at which the satellites locate from the host galaxy, and the mass ratio between the host galaxies and their satellites. The three virtual galaxy catalogs considered here overproduce the fraction of galaxies with satellites by a factor ranging between 1.5 and 6 depending on the epoch, whereas the mean projected distance and ratio of the satellite mass over host mass are in closer agreement with data. The larger pull of satellites in the semi-analytical samples could suggest that the size evolution found in previous hydrodynamical simulations is an artifact due to the larger number of infalling satellites compared to the real universe. These results advise us to revise the physical ingredients implemented in the semi-analytical models in order to reconcile the observed and computed fraction of galaxies with satellites, and eventually, it would leave some room for other mechanisms explaining the galaxy size growth not related to the minor merging.

  20. VizieR Online Data Catalog: Massive early-type galaxies (Buitrago+, 2013)

    NASA Astrophysics Data System (ADS)

    Buitrago, F.; Trujillo, I.; Conselice, C. J.; Haussler, B.

    2013-08-01

    Present-day massive galaxies are composed mostly of early-type objects. It is unknown whether this was also the case at higher redshifts. In a hierarchical assembling scenario the morphological content of the massive population is expected to change with time from disc-like objects in the early Universe to spheroid-like galaxies at present. In this paper we have probed this theoretical expectation by compiling a large sample of massive (Mstellar>=1011h-270M⊙) galaxies in the redshift interval 0galaxies selected from Sloan Digital Sky Survey plus 875 objects observed with the Hubble Space Telescope belonging to the Palomar Observatory Wide-field InfraRed/DEEP2 and GOODS NICMOS Survey surveys. 639 of our objects have spectroscopic redshifts. Our morphological classification is performed as close as possible to the optical rest frame according to the photometric bands available in our observations both quantitatively (using the Sersic index as a morphological proxy) and qualitatively (by visual inspection). Using both techniques we find an enormous change on the dominant morphological class with cosmic time. The fraction of early-type galaxies among the massive galaxy population has changed from ~20-30 per cent at z~3 to~70 per cent at z=0. Early-type galaxies have been the predominant morphological class for massive galaxies since only z~1. (1 data file).

  1. The cosmic assembly of stellar haloes in massive Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Buitrago, Fernando; Trujillo, Ignacio; Curtis-Lake, Emma; Montes, Mireia; Cooper, Andrew P.; Bruce, Victoria A.; Pérez-González, Pablo G.; Cirasuolo, Michele

    2017-01-01

    Using the exquisite depth of the Hubble Ultra Deep Field (HUDF12 programme) dataset, we explore the ongoing assembly of the outermost regions of the most massive galaxies (M_stellar≥5× 1010 M⊙) at z ≤ 1. The outskirts of massive objects, particularly Early-Types Galaxies (ETGs), are expected to suffer a dramatic transformation across cosmic time due to continuous accretion of small galaxies. HUDF imaging allows us to study this process at intermediate redshifts in 6 massive galaxies, exploring the individual surface brightness profiles out to ˜25 effective radii. We find that 5-20% of the total stellar mass for the galaxies in our sample is contained within 10 galaxies (≲5%). The fraction of stellar mass stored in the outer envelopes/haloes of Massive Early-Type Galaxies increases with decreasing redshift, being 28.7% at = 0.1, 15.1% at = 0.65 and 3.5% at = 2. The fraction of mass in diffuse features linked with ongoing minor merger events is > 1-2%, very similar to predictions based on observed close pair counts. Therefore, the results for our small albeit meaningful sample suggest that the size and mass growth of the most massive galaxies have been solely driven by minor and major merging from z = 1 to today.

  2. Cosmology and astrophysics from relaxed galaxy clusters - IV. Robustly calibrating hydrostatic masses with weak lensing

    NASA Astrophysics Data System (ADS)

    Applegate, D. E.; Mantz, A.; Allen, S. W.; der Linden, A. von; Morris, R. Glenn; Hilbert, S.; Kelly, Patrick L.; Burke, D. L.; Ebeling, H.; Rapetti, D. A.; Schmidt, R. W.

    2016-04-01

    This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses measures the combined bias of X-ray hydrostatic masses from both astrophysical and instrumental sources. While we cannot disentangle the two sources of bias, only the combined bias is relevant for calibrating cosmological measurements using relaxed clusters. Assuming a fixed cosmology, and within a characteristic radius (r2500) determined from the X-ray data, we measure a lensing to X-ray mass ratio of 0.96 ± 9 per cent (stat) ± 9 per cent (sys). We find no significant trends of this ratio with mass, redshift or the morphological indicators used to select the sample. Our results imply that any departures from hydrostatic equilibrium at these radii are offset by calibration errors of comparable magnitude, with large departures of tens-of-percent unlikely. In addition, we find a mean concentration of the sample measured from lensing data of c_{200} = 3.0_{-1.8}^{+4.4}. Anticipated short-term improvements in lensing systematics, and a modest expansion of the relaxed lensing sample, can easily increase the measurement precision by 30-50 per cent, leading to similar improvements in cosmological constraints that employ X-ray hydrostatic mass estimates, such as on Ωm from the cluster gas mass fraction.

  3. Cosmology and astrophysics from relaxed galaxy clusters - IV: Robustly calibrating hydrostatic masses with weak lensing

    SciTech Connect

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

    2016-02-04

    This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses measures the combined bias of X-ray hydrostatic masses from both astrophysical and instrumental sources. While we cannot disentangle the two sources of bias, only the combined bias is relevant for calibrating cosmological measurements using relaxed clusters. Assuming a fixed cosmology, and within a characteristic radius (r2500) determined from the X-ray data, we measure a lensing to X-ray mass ratio of 0.96 ± 9% (stat) ± 9% (sys). We find no significant trends of this ratio with mass, redshift or the morphological indicators used to select the sample. Our results imply that any departures from hydrostatic equilibrium at these radii are offset by calibration errors of comparable magnitude, with large departures of tens-of-percent unlikely. In addition, we find a mean concentration of the sample measured from lensing data of c200 = 3.0+4.4–1.8. In conclusion, anticipated short-term improvements in lensing systematics, and a modest expansion of the relaxed lensing sample, can easily increase the measurement precision by 30–50%, leading to similar improvements in cosmological constraints that employ X-ray hydrostatic mass estimates, such as on Ωm from the cluster gas mass fraction.

  4. Cosmology and astrophysics from relaxed galaxy clusters - IV: Robustly calibrating hydrostatic masses with weak lensing

    DOE PAGES

    Applegate, D. E; Mantz, A.; Allen, S. W.; ...

    2016-02-04

    This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses measures the combined bias of X-ray hydrostatic masses from both astrophysical and instrumental sources. While we cannot disentangle the two sources of bias, only the combined bias is relevant for calibrating cosmological measurements using relaxed clusters. Assuming a fixed cosmology, and within amore » characteristic radius (r2500) determined from the X-ray data, we measure a lensing to X-ray mass ratio of 0.96 ± 9% (stat) ± 9% (sys). We find no significant trends of this ratio with mass, redshift or the morphological indicators used to select the sample. Our results imply that any departures from hydrostatic equilibrium at these radii are offset by calibration errors of comparable magnitude, with large departures of tens-of-percent unlikely. In addition, we find a mean concentration of the sample measured from lensing data of c200 = 3.0+4.4–1.8. In conclusion, anticipated short-term improvements in lensing systematics, and a modest expansion of the relaxed lensing sample, can easily increase the measurement precision by 30–50%, leading to similar improvements in cosmological constraints that employ X-ray hydrostatic mass estimates, such as on Ωm from the cluster gas mass fraction.« less

  5. Mass and galaxy distributions of four massive galaxy clusters from Dark Energy Survey Science Verification data

    SciTech Connect

    Melchior, P.; Suchyta, E.; Huff, E.; Hirsch, M.; Kacprzak, T.; Rykoff, E.; Gruen, D.; Armstrong, R.; Bacon, D.; Bechtol, K.; Bernstein, G. M.; Bridle, S.; Clampitt, J.; Honscheid, K.; Jain, B.; Jouvel, S.; Krause, E.; Lin, H.; MacCrann, N.; Patton, K.; Plazas, A.; Rowe, B.; Vikram, V.; Wilcox, H.; Young, J.; Zuntz, J.; Abbott, T.; Abdalla, F. B.; Allam, S. S.; Banerji, M.; Bernstein, J. P.; Bernstein, R. A.; Bertin, E.; Buckley-Geer, E.; Burke, D. L.; Castander, F. J.; da Costa, L. N.; Cunha, C. E.; Depoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; Evrard, A. E.; Neto, A. F.; Fernandez, E.; Finley, D. A.; Flaugher, B.; Frieman, J. A.; Gaztanaga, E.; Gerdes, D.; Gruendl, R. A.; Gutierrez, G. R.; Jarvis, M.; Karliner, I.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Maia, M. A. G.; Makler, M.; Marriner, J.; Marshall, J. L.; Merritt, K. W.; Miller, C. J.; Miquel, R.; Mohr, J.; Neilsen, E.; Nichol, R. C.; Nord, B. D.; Reil, K.; Roe, N. A.; Roodman, A.; Sako, M.; Sanchez, E.; Santiago, B. X.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, C.; Soares-Santos, M.; Swanson, M. E. C.; Sypniewski, A. J.; Tarle, G.; Thaler, J.; Thomas, D.; Tucker, D. L.; Walker, A.; Wechsler, R.; Weller, J.; Wester, W.

    2015-03-31

    We measure the weak-lensing masses and galaxy distributions of four massive galaxy clusters observed during the Science Verification phase of the Dark Energy Survey. This pathfinder study is meant to 1) validate the DECam imager for the task of measuring weak-lensing shapes, and 2) utilize DECam's large field of view to map out the clusters and their environments over 90 arcmin. We conduct a series of rigorous tests on astrometry, photometry, image quality, PSF modeling, and shear measurement accuracy to single out flaws in the data and also to identify the optimal data processing steps and parameters. We find Science Verification data from DECam to be suitable for the lensing analysis described in this paper. The PSF is generally well-behaved, but the modeling is rendered difficult by a flux-dependent PSF width and ellipticity. We employ photometric redshifts to distinguish between foreground and background galaxies, and a red-sequence cluster finder to provide cluster richness estimates and cluster-galaxy distributions. By fitting NFW profiles to the clusters in this study, we determine weak-lensing masses that are in agreement with previous work. For Abell 3261, we provide the first estimates of redshift, weak-lensing mass, and richness. In addition, the cluster-galaxy distributions indicate the presence of filamentary structures attached to 1E 0657-56 and RXC J2248.7-4431, stretching out as far as 1 degree (approximately 20 Mpc), showcasing the potential of DECam and DES for detailed studies of degree-scale features on the sky.

  6. Mass and galaxy distributions of four massive galaxy clusters from Dark Energy Survey Science Verification data

    SciTech Connect

    Melchior, P.; Suchyta, E.; Huff, E.; Hirsch, M.; Kacprzak, T.; Rykoff, E.; Gruen, D.; Armstrong, R.; Bacon, D.; Bechtol, K.; Bernstein, G. M.; Bridle, S.; Clampitt, J.; Honscheid, K.; Jain, B.; Jouvel, S.; Krause, E.; Lin, H.; MacCrann, N.; Patton, K.; Plazas, A.; Rowe, B.; Vikram, V.; Wilcox, H.; Young, J.; Zuntz, J.; Abbott, T.; Abdalla, F. B.; Allam, S. S.; Banerji, M.; Bernstein, J. P.; Bernstein, R. A.; Bertin, E.; Buckley-Geer, E.; Burke, D. L.; Castander, F. J.; da Costa, L. N.; Cunha, C. E.; Depoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; Evrard, A. E.; Neto, A. F.; Fernandez, E.; Finley, D. A.; Flaugher, B.; Frieman, J. A.; Gaztanaga, E.; Gerdes, D.; Gruendl, R. A.; Gutierrez, G. R.; Jarvis, M.; Karliner, I.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Maia, M. A. G.; Makler, M.; Marriner, J.; Marshall, J. L.; Merritt, K. W.; Miller, C. J.; Miquel, R.; Mohr, J.; Neilsen, E.; Nichol, R. C.; Nord, B. D.; Reil, K.; Roe, N. A.; Roodman, A.; Sako, M.; Sanchez, E.; Santiago, B. X.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, C.; Soares-Santos, M.; Swanson, M. E. C.; Sypniewski, A. J.; Tarle, G.; Thaler, J.; Thomas, D.; Tucker, D. L.; Walker, A.; Wechsler, R.; Weller, J.; Wester, W.

    2015-03-31

    We measure the weak lensing masses and galaxy distributions of four massive galaxy clusters observed during the Science Verification phase of the Dark Energy Survey (DES). This pathfinder study is meant to (1) validate the Dark Energy Camera (DECam) imager for the task of measuring weak lensing shapes, and (2) utilize DECam's large field of view to map out the clusters and their environments over 90 arcmin. We conduct a series of rigorous tests on astrometry, photometry, image quality, point spread function (PSF) modelling, and shear measurement accuracy to single out flaws in the data and also to identify the optimal data processing steps and parameters. We find Science Verification data from DECam to be suitable for the lensing analysis described in this paper. The PSF is generally well behaved, but the modelling is rendered difficult by a flux-dependent PSF width and ellipticity. We employ photometric redshifts to distinguish between foreground and background galaxies, and a red-sequence cluster finder to provide cluster richness estimates and cluster-galaxy distributions. By fitting Navarro-Frenk-White profiles to the clusters in this study, we determine weak lensing masses that are in agreement with previous work. For Abell 3261, we provide the first estimates of redshift, weak lensing mass, and richness. In addition, the cluster-galaxy distributions indicate the presence of filamentary structures attached to 1E 0657-56 and RXC J2248.7-4431, stretching out as far as 1. (approximately 20 Mpc), showcasing the potential of DECam and DES for detailed studies of degree-scale features on the sky.

  7. Mass and galaxy distributions of four massive galaxy clusters from Dark Energy Survey Science Verification data

    DOE PAGES

    Melchior, P.; Suchyta, E.; Huff, E.; ...

    2015-03-31

    We measure the weak-lensing masses and galaxy distributions of four massive galaxy clusters observed during the Science Verification phase of the Dark Energy Survey. This pathfinder study is meant to 1) validate the DECam imager for the task of measuring weak-lensing shapes, and 2) utilize DECam's large field of view to map out the clusters and their environments over 90 arcmin. We conduct a series of rigorous tests on astrometry, photometry, image quality, PSF modelling, and shear measurement accuracy to single out flaws in the data and also to identify the optimal data processing steps and parameters. We find Sciencemore » Verification data from DECam to be suitable for the lensing analysis described in this paper. The PSF is generally well-behaved, but the modelling is rendered difficult by a flux-dependent PSF width and ellipticity. We employ photometric redshifts to distinguish between foreground and background galaxies, and a red-sequence cluster finder to provide cluster richness estimates and cluster-galaxy distributions. By fitting NFW profiles to the clusters in this study, we determine weak-lensing masses that are in agreement with previous work. For Abell 3261, we provide the first estimates of redshift, weak-lensing mass, and richness. Additionally, the cluster-galaxy distributions indicate the presence of filamentary structures attached to 1E 0657-56 and RXC J2248.7-4431, stretching out as far as 1degree (approximately 20 Mpc), showcasing the potential of DECam and DES for detailed studies of degree-scale features on the sky.« less

  8. Mass and galaxy distributions of four massive galaxy clusters from Dark Energy Survey Science Verification data

    SciTech Connect

    Melchior, P.; Suchyta, E.; Huff, E.; Hirsch, M.; Kacprzak, T.; Rykoff, E.; Gruen, D.; Armstrong, R.; Bacon, D.; Bechtol, K.; Bernstein, G. M.; Bridle, S.; Clampitt, J.; Honscheid, K.; Jain, B.; Jouvel, S.; Krause, E.; Lin, H.; MacCrann, N.; Patton, K.; Plazas, A.; Rowe, B.; Vikram, V.; Wilcox, H.; Young, J.; Zuntz, J.; Abbott, T.; Abdalla, F. B.; Allam, S. S.; Banerji, M.; Bernstein, J. P.; Bernstein, R. A.; Bertin, E.; Buckley-Geer, E.; Burke, D. L.; Castander, F. J.; da Costa, L. N.; Cunha, C. E.; Depoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; Evrard, A. E.; Neto, A. F.; Fernandez, E.; Finley, D. A.; Flaugher, B.; Frieman, J. A.; Gaztanaga, E.; Gerdes, D.; Gruendl, R. A.; Gutierrez, G. R.; Jarvis, M.; Karliner, I.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Maia, M. A. G.; Makler, M.; Marriner, J.; Marshall, J. L.; Merritt, K. W.; Miller, C. J.; Miquel, R.; Mohr, J.; Neilsen, E.; Nichol, R. C.; Nord, B. D.; Reil, K.; Roe, N. A.; Roodman, A.; Sako, M.; Sanchez, E.; Santiago, B. X.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, C.; Soares-Santos, M.; Swanson, M. E. C.; Sypniewski, A. J.; Tarle, G.; Thaler, J.; Thomas, D.; Tucker, D. L.; Walker, A.; Wechsler, R.; Weller, J.; Wester, W.

    2015-03-31

    We measure the weak-lensing masses and galaxy distributions of four massive galaxy clusters observed during the Science Verification phase of the Dark Energy Survey. This pathfinder study is meant to 1) validate the DECam imager for the task of measuring weak-lensing shapes, and 2) utilize DECam's large field of view to map out the clusters and their environments over 90 arcmin. We conduct a series of rigorous tests on astrometry, photometry, image quality, PSF modelling, and shear measurement accuracy to single out flaws in the data and also to identify the optimal data processing steps and parameters. We find Science Verification data from DECam to be suitable for the lensing analysis described in this paper. The PSF is generally well-behaved, but the modelling is rendered difficult by a flux-dependent PSF width and ellipticity. We employ photometric redshifts to distinguish between foreground and background galaxies, and a red-sequence cluster finder to provide cluster richness estimates and cluster-galaxy distributions. By fitting NFW profiles to the clusters in this study, we determine weak-lensing masses that are in agreement with previous work. For Abell 3261, we provide the first estimates of redshift, weak-lensing mass, and richness. Additionally, the cluster-galaxy distributions indicate the presence of filamentary structures attached to 1E 0657-56 and RXC J2248.7-4431, stretching out as far as 1degree (approximately 20 Mpc), showcasing the potential of DECam and DES for detailed studies of degree-scale features on the sky.

  9. High molecular gas fractions in normal massive star-forming galaxies in the young Universe.

    PubMed

    Tacconi, L J; Genzel, R; Neri, R; Cox, P; Cooper, M C; Shapiro, K; Bolatto, A; Bouché, N; Bournaud, F; Burkert, A; Combes, F; Comerford, J; Davis, M; Schreiber, N M Förster; Garcia-Burillo, S; Gracia-Carpio, J; Lutz, D; Naab, T; Omont, A; Shapley, A; Sternberg, A; Weiner, B

    2010-02-11

    Stars form from cold molecular interstellar gas. As this is relatively rare in the local Universe, galaxies like the Milky Way form only a few new stars per year. Typical massive galaxies in the distant Universe formed stars an order of magnitude more rapidly. Unless star formation was significantly more efficient, this difference suggests that young galaxies were much more molecular-gas rich. Molecular gas observations in the distant Universe have so far largely been restricted to very luminous, rare objects, including mergers and quasars, and accordingly we do not yet have a clear idea about the gas content of more normal (albeit massive) galaxies. Here we report the results of a survey of molecular gas in samples of typical massive-star-forming galaxies at mean redshifts of about 1.2 and 2.3, when the Universe was respectively 40% and 24% of its current age. Our measurements reveal that distant star forming galaxies were indeed gas rich, and that the star formation efficiency is not strongly dependent on cosmic epoch. The average fraction of cold gas relative to total galaxy baryonic mass at z = 2.3 and z = 1.2 is respectively about 44% and 34%, three to ten times higher than in today's massive spiral galaxies. The slow decrease between z approximately 2 and z approximately 1 probably requires a mechanism of semi-continuous replenishment of fresh gas to the young galaxies.

  10. Dusty Feedback from Massive Black Holes in Two Elliptical Galaxies

    NASA Technical Reports Server (NTRS)

    Temi, P.; Brighenti, F.; Mathews, W. G.; Amblard, A.; Riguccini, L.

    2013-01-01

    Far-infrared dust emission from elliptical galaxies informs us about galaxy mergers, feedback energy outbursts from supermassive black holes and the age of galactic stars. We report on the role of AGN feedback observationally by looking for its signatures in elliptical galaxies at recent epochs in the nearby universe. We present Herschel observations of two elliptical galaxies with strong and spatially extended FIR emission from colder grains 5-10 kpc distant from the galaxy cores. Extended excess cold dust emission is interpreted as evidence of recent feedback-generated AGN energy outbursts in these galaxies, visible only in the FIR, from buoyant gaseous outflows from the galaxy cores.

  11. CORE CREATION IN GALAXIES AND HALOS VIA SINKING MASSIVE OBJECTS

    SciTech Connect

    Goerdt, Tobias; Moore, Ben; Stadel, Joachim; Read, J. I.

    2010-12-20

    We perform a detailed investigation into the disruption of central cusps via the transfer of energy from sinking massive objects. Constant density inner regions form at the radius where the enclosed mass approximately matches the mass of the infalling body. We explore parameter space using numerical simulations and give an empirical relation for the size of the resulting core within structures that have different initial cusp slopes. We find that infalling bodies always stall at the edge of these newly formed cores, experiencing no dynamical friction over many dynamical times. As applications, we consider the resulting decrease in the dark matter annihilation flux due to centrally destroyed cusps, and we present a new theory for the formation of close binary nuclei-the 'stalled binary' model. We focus on one particularly interesting binary nucleus system, the dwarf spheroidal galaxy VCC 128 which is dark matter dominated at all radii. We show that its nuclei would rapidly coalesce within a few million years if it has a central dark matter cusp slope steeper than r {sup -1}. However, if its initial dark matter cusp is slightly shallower than a logslope of -0.75 at {approx}0.1% of the virial radius, then the sinking nuclei naturally create a core equal to their observed separation and stall. This is close to the logslope measured in a recent billion particle cold dark matter halo simulation.

  12. SUPERDENSE MASSIVE GALAXIES IN THE ESO DISTANT CLUSTER SURVEY (EDisCS)

    SciTech Connect

    Valentinuzzi, T.; D'onofrio, M.; Vulcani, B.; Poggianti, B. M.; Fritz, J.; Moretti, A.; Saglia, R. P.; Aragon-Salamanca, A.; Simard, L.; Sanchez-Blazquez, P.; Cava, A.; Couch, W. J.

    2010-09-20

    We find a significant number of massive and compact galaxies in clusters from the ESO Distant Clusters Survey (EDisCS) at 0.4 < z < 1. They have similar stellar masses, ages, sizes, and axial ratios to local z {approx} 0.04 compact galaxies in WIde field Nearby Galaxy clusters Survey (WINGS) clusters, and to z = 1.4-2 massive and passive galaxies found in the general field. If non-brightest cluster galaxies of all densities, morphologies, and spectral types are considered, the median size of EDisCS galaxies is only a factor 1.18 smaller than in WINGS. We show that for morphologically selected samples, the morphological evolution taking place in a significant fraction of galaxies during the last Gyr may introduce an apparent, spurious evolution of size with redshift, which is actually due to intrinsic differences in the selected samples. We conclude that the median mass-size relation of cluster galaxies does not evolve significantly from z {approx} 0.7 to z {approx} 0.04. In contrast, the masses and sizes of BCGs and galaxies with M {sub *}>4 x 10{sup 11} M {sub sun} have significantly increased by a factor of 2 and 4, respectively, confirming the results of a number of recent works on the subject. Our findings show that progenitor bias effects play an important role in the size-growth paradigm of massive and passive galaxies.

  13. The fate of high redshift massive compact galaxies in dense environments

    SciTech Connect

    Kaufmann, Tobias; Mayer, Lucio; Carollo, Marcella; Feldmann, Robert; /Fermilab /Chicago U., KICP

    2012-01-01

    Massive compact galaxies seem to be more common at high redshift than in the local universe, especially in denser environments. To investigate the fate of such massive galaxies identified at z {approx} 2 we analyse the evolution of their properties in three cosmological hydrodynamical simulations that form virialized galaxy groups of mass {approx} 10{sup 13} M{sub {circle_dot}} hosting a central massive elliptical/S0 galaxy by redshift zero. We find that at redshift {approx} 2 the population of galaxies with M{sub *} > 2 x 10{sup 10} M{sub {circle_dot}} is diverse in terms of mass, velocity dispersion, star formation and effective radius, containing both very compact and relatively extended objects. In each simulation all the compact satellite galaxies have merged into the central galaxy by redshift 0 (with the exception of one simulation where one of such satellite galaxy survives). Satellites of similar mass at z = 0 are all less compact than their high redshift counterparts. They form later than the galaxies in the z = 2 sample and enter the group potential at z < 1, when dynamical friction times are longer than the Hubble time. Also, by z = 0 the central galaxies have increased substantially their characteristic radius via a combination of in situ star formation and mergers. Hence in a group environment descendants of compact galaxies either evolve towards larger sizes or they disappear before the present time as a result of the environment in which they evolve. Since the group-sized halos that we consider are representative of dense environments in the {Lambda}CDM cosmology, we conclude that the majority of high redshift compact massive galaxies do not survive until today as a result of the environment.

  14. Cosmology and astrophysics from relaxed galaxy clusters – V. Consistency with cold dark matter structure formation

    SciTech Connect

    Mantz, A. B.; Allen, S. W.; Morris, R. G.

    2016-07-15

    This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the cold dark matter (CDM) paradigm. In addition, we present constraints on the concentration–mass relation for massive clusters, finding a power-law mass dependence with a slope of κm = –0.16 ± 0.07, in agreement with CDM predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κζ = –0.17 ± 0.26), with an intrinsic scatter of σln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ~50 kpc–1 Mpc), and test for departures from the simple Navarro–Frenk–White (NFW) form, for which the logarithmic slope of the density profile tends to –1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σβ = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σα = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.

  15. INSIGHTS ON THE FORMATION, EVOLUTION, AND ACTIVITY OF MASSIVE GALAXIES FROM ULTRACOMPACT AND DISKY GALAXIES AT z = 2-3

    SciTech Connect

    Weinzirl, Tim; Jogee, Shardha; Conselice, Christopher J.; Gruetzbauch, Ruth; Buitrago, Fernando; Papovich, Casey; Chary, Ranga-Ram; Bluck, Asa; Mobasher, Bahram; Lucas, Ray A.; Dickinson, Mark; Bauer, Amanda E.

    2011-12-10

    We present our results on the structure and activity of massive galaxies at z = 1-3 using one of the largest (166 with M{sub *} {>=} 5 Multiplication-Sign 10{sup 10} M{sub Sun }) and most diverse samples of massive galaxies derived from the GOODS-NICMOS survey: (1) Sersic fits to deep NIC3 F160W images indicate that the rest-frame optical structures of massive galaxies are very different at z = 2-3 compared to z {approx} 0. Approximately 40% of massive galaxies are ultracompact (r{sub e} {<=} 2 kpc), compared to less than 1% at z {approx} 0. Furthermore, most ({approx}65%) systems at z = 2-3 have a low Sersic index n {<=} 2, compared to {approx}13% at z {approx} 0. We present evidence that the n {<=} 2 systems at z = 2-3 likely contain prominent disks, unlike most massive z {approx} 0 systems. (2) There is a correlation between structure and star formation rates (SFRs). The majority ({approx}85%) of non-active galactic nucleus (AGN) massive galaxies at z = 2-3, with SFR high enough to yield a 5{sigma} (30 {mu}Jy) 24 {mu}m Spitzer detection, have low n {<=} 2. Such n {<=} 2 systems host the highest SFR. (3) The frequency of AGNs is {approx}40% at z = 2-3. Most ({approx}65%) AGN hosts have disky (n {<=} 2) morphologies. Ultracompact galaxies appear quiescent in terms of both AGN activity and star formation. (4) Large stellar surface densities imply massive galaxies at z = 2-3 formed via rapid, highly dissipative events at z > 2. The large fraction of n {<=} 2 disky systems suggests cold mode accretion complements gas-rich major mergers at z > 2. In order for massive galaxies at z = 2-3 to evolve into present-day massive E/S0s, they need to significantly increase (n, r{sub e} ). Dry minor and major mergers may play an important role in this process.

  16. Environment and Structure of Massive Central Galaxies through the Eye of Hyper Suprime-Cam

    NASA Astrophysics Data System (ADS)

    Huang, Song; HSC Survey Collaboration

    2017-01-01

    Although the environmental dependence of structures for massive central galaxies is predicted by the promising hierarchical assembly model, observations at low redshift seem to find no convincing evidence of that. With the help of deep i-band images of a large sample of massive central galaxies at 0.3 < z < 0.5 from the Subaru Hyper Suprime-Cam (HSC) survey, we map their stellar mass distributions out to radius larger than 100 kpc, and discover subtle, but systematic and robust structural differences that depend on halo mass. At fixed stellar mass within 100 kpc, the massive central galaxies in more massive (M_{200,c} > 1.6x10^14 M_sun$) halos have a slightly flattened inner profile within ~15-20 kpc, and a more prominent outer envelope compared to ones in less massive (M_{200,c} < 8.7\\x10^13 M_sun) halos. For centrals with M_* > 10^11.5 M_sun, the ones in more massive halos show very significant excess of mass in the outskirt when the two samples are matched using proxies of mass assembled at z > 1. Such differences are broadly consistent with richer recent merging history for more massive halos. We suggest that the relation between total stellar mass and mass within inner 5 or 10 kpc is potentially interesting for diagnosing the role played by host halo in shaping the structures of massive central galaxies. These results also highlight the importance of deep photometry and the usage of detailed structural information in the study of the assembly history of galaxies. We also show that the radial profiles of ellipticity and optical color, along with the preliminary weak lensing signals will enable us gain more insights about the evolution of massive galaxies.

  17. The diverse evolutionary paths of simulated high-z massive, compact galaxies to z = 0

    NASA Astrophysics Data System (ADS)

    Wellons, Sarah; Torrey, Paul; Ma, Chung-Pei; Rodriguez-Gomez, Vicente; Pillepich, Annalisa; Nelson, Dylan; Genel, Shy; Vogelsberger, Mark; Hernquist, Lars

    2016-02-01

    Massive quiescent galaxies have much smaller physical sizes at high redshift than today. The strong evolution of galaxy size may be caused by progenitor bias, major and minor mergers, adiabatic expansion, and/or renewed star formation, but it is difficult to test these theories observationally. Herein, we select a sample of 35 massive, compact galaxies (M* = 1-3 × 1011 M⊙, M*/R1.5 > 1010.5 M⊙/kpc1.5) at z = 2 in the cosmological hydrodynamical simulation Illustris and trace them forwards to z = 0 to uncover their evolution and identify their descendants. By z = 0, the original factor of 3 difference in stellar mass spreads to a factor of 20. The dark matter halo masses similarly spread from a factor of 5 to 40. The galaxies' evolutionary paths are diverse: about half acquire an ex situ envelope and are the core of a more massive descendant, a third survive undisturbed and gain very little mass, 15 per cent are consumed in a merger with a more massive galaxy, and a small remainder are thoroughly mixed by major mergers. The galaxies grow in size as well as mass, and only ˜10 per cent remain compact by z = 0. The majority of the size growth is driven by the acquisition of ex situ mass. The most massive galaxies at z = 0 are the most likely to have compact progenitors, but this trend possesses significant dispersion which precludes a direct linkage to compact galaxies at z = 2. The compact galaxies' merger rates are influenced by their z = 2 environments, so that isolated or satellite compact galaxies (which are protected from mergers) are the most likely to survive to the present day.

  18. NIR SPECTROSCOPIC OBSERVATION OF MASSIVE GALAXIES IN THE PROTOCLUSTER AT z = 3.09

    SciTech Connect

    Kubo, Mariko; Yamada, Toru; Ichikawa, Takashi; Kajisawa, Masaru; Matsuda, Yuichi; Tanaka, Ichi

    2015-01-20

    We present the results of near-infrared spectroscopic observations of the K-band-selected candidate galaxies in the protocluster at z = 3.09 in the SSA22 field. We observed 67 candidates with K {sub AB} < 24 and confirmed redshifts of the 39 galaxies at 2.0 < z {sub spec} < 3.4. Of the 67 candidates, 24 are certainly protocluster members with 3.04 ≤ z {sub spec} ≤ 3.12, which are massive red galaxies that have been unidentified in previous optical observations of the SSA22 protocluster. Many distant red galaxies (J – K {sub AB} > 1.4), hyper extremely red objects (J – K {sub AB} > 2.1), Spitzer MIPS 24 μm sources, active galactic nuclei (AGNs) as well as the counterparts of Lyα blobs and the AzTEC/ASTE 1.1 mm sources in the SSA22 field are also found to be protocluster members. The mass of the SSA22 protocluster is estimated to be ∼2-5 × 10{sup 14} M {sub ☉}, and this system is plausibly a progenitor of the most massive clusters of galaxies in the current universe. The reddest (J – K {sub AB} ≥ 2.4) protocluster galaxies are massive galaxies with M {sub star} ∼ 10{sup 11} M {sub ☉} showing quiescent star formation activities and plausibly dominated by old stellar populations. Most of these massive quiescent galaxies host moderately luminous AGNs detected by X-ray. There are no significant differences in the [O III] λ5007/Hβ emission line ratios and [O III] λ5007 line widths and spatial extents of the protocluster galaxies from those of massive galaxies at z ∼ 2-3 in the general field.

  19. Shaping massive galaxies: their morphology and kinematics at z = 1-3

    NASA Astrophysics Data System (ADS)

    Buitrago, F.; Conselice, C. J.; Epinat, B.; Bedregal, A. G.; Trujillo, I.; Grützbauch, R.

    2011-11-01

    Massive (M_* ≥ 10^{11} M_⊙) galaxies at high redshift (z ≥ 1.5) remain mysterious objects. Their extremely small sizes (effective radii of 1-2 kpc) make them as dense as modern globular clusters. It is thought that a highly dissipational merger is needed to create such compact galaxies. Within this proceedings, we discuss this issue, along with state-of-the-art morphological and kinematic observations of these objects. In the present day Universe massive galaxies contain large sizes, and harbour old and metal-rich stellar populations. In order to explore their development, we present near-IR IFU observations with SINFONI@VLT for ten massive galaxies at z ˜ 1.4 solely selected by their high stellar mass which allows us to retrieve velocity dispersions, kinematic maps and dynamical masses. We combine this with data from the GOODS NICMOS Survey, the largest sample of massive galaxies (80 objects) with high-resolution imaging at high redshift (1.7 < z < 3) acquired to date. As a result, we show how massive galaxy morphology changes possibly result through elusive minor merging.

  20. A massive protocluster of galaxies at a redshift of z ≈ 5.3.

    PubMed

    Capak, Peter L; Riechers, Dominik; Scoville, Nick Z; Carilli, Chris; Cox, Pierre; Neri, Roberto; Robertson, Brant; Salvato, Mara; Schinnerer, Eva; Yan, Lin; Wilson, Grant W; Yun, Min; Civano, Francesca; Elvis, Martin; Karim, Alexander; Mobasher, Bahram; Staguhn, Johannes G

    2011-02-10

    Massive clusters of galaxies have been found that date from as early as 3.9 billion years (3.9 Gyr; z = 1.62) after the Big Bang, containing stars that formed at even earlier epochs. Cosmological simulations using the current cold dark matter model predict that these systems should descend from 'protoclusters'-early overdensities of massive galaxies that merge hierarchically to form a cluster. These protocluster regions themselves are built up hierarchically and so are expected to contain extremely massive galaxies that can be observed as luminous quasars and starbursts. Observational evidence for this picture, however, is sparse because high-redshift protoclusters are rare and difficult to observe. Here we report a protocluster region that dates from 1 Gyr (z = 5.3) after the Big Bang. This cluster of massive galaxies extends over more than 13 megaparsecs and contains a luminous quasar as well as a system rich in molecular gas. These massive galaxies place a lower limit of more than 4 × 10(11) solar masses of dark and luminous matter in this region, consistent with that expected from cosmological simulations for the earliest galaxy clusters.

  1. The intriguing properties of local compact massive galaxies: What are they?

    NASA Astrophysics Data System (ADS)

    Ferré-Mateu, A.; Vazdekis, A.; Trujillo, I.; Sánchez-Blázquez, P.; Ricciardelli, E.; de la Rosa, I. G.

    2013-07-01

    Studying the properties of the few compact massive galaxies that exist in the local Universe (Trujillo et al. 2009) might provide a closer look to the nature of their high redshift (z >= 1.0) massive counterparts. By this means we have characterized their main kinematics, structural properties, stellar populations and star formation histories with a set of new high quality spectroscopic and imaging data (Ferré-Mateu et al. 2012 and Trujillo et al. 2012). These galaxies seem to be truly unique, as they do not follow the characteristic kinematics, stellar surface mass density profiles and stellar population patterns of present-day massive ellipticals or spirals of similar mass. They are, instead, more alike their high-z analogs. Summarizing, local compact massive galaxies are rare, unique and the perfect laboratory to study their high redshift counterparts.

  2. A high stellar velocity dispersion for a compact massive galaxy at redshift z = 2.186.

    PubMed

    van Dokkum, Pieter G; Kriek, Mariska; Franx, Marijn

    2009-08-06

    Recent studies have found that the oldest and most luminous galaxies in the early Universe are surprisingly compact, having stellar masses similar to present-day elliptical galaxies but much smaller sizes. This finding has attracted considerable attention, as it suggests that massive galaxies have grown in size by a factor of about five over the past ten billion years (10 Gyr). A key test of these results is a determination of the stellar kinematics of one of the compact galaxies: if the sizes of these objects are as extreme as has been claimed, their stars are expected to have much higher velocities than those in present-day galaxies of the same mass. Here we report a measurement of the stellar velocity dispersion of a massive compact galaxy at redshift z = 2.186, corresponding to a look-back time of 10.7 Gyr. The velocity dispersion is very high at km s(-1), consistent with the mass and compactness of the galaxy inferred from photometric data. This would indicate significant recent structural and dynamical evolution of massive galaxies over the past 10 Gyr. The uncertainty in the dispersion was determined from simulations that include the effects of noise and template mismatch. However, we cannot exclude the possibility that some subtle systematic effect may have influenced the analysis, given the low signal-to-noise ratio of our spectrum.

  3. ULTRA-DEEP SUB-KILOPARSEC VIEW OF NEARBY MASSIVE COMPACT GALAXIES

    SciTech Connect

    Trujillo, Ignacio; Ferre-Mateu, Anna

    2012-05-20

    Using Gemini North telescope ultra-deep and high-resolution (sub-kiloparsec) K-band adaptive optics imaging of a sample of four nearby (z {approx} 0.15) massive ({approx}10{sup 11} M{sub Sun }) compact (R < 1.5 kpc) galaxies, we have explored the structural properties of these rare objects with unprecedented detail. Our surface brightness profiles expand over 12 mag in range allowing us to explore the presence of any faint extended envelope on these objects down to stellar mass densities {approx}10{sup 6} M{sub Sun} kpc{sup -2} at radial distances of {approx}15 kpc. We find no evidence for any extended faint tail altering the compactness of these galaxies. Our objects are elongated, visually resembling S0 galaxies, and have a central stellar mass density well above the stellar mass densities of objects with similar stellar mass but normal size in the present universe. If these massive compact objects will eventually transform into normal size galaxies, the processes driving this size growth will have to migrate around (2-3) Multiplication-Sign 10{sup 10} M{sub Sun} stellar mass from their inner (R < 1.7 kpc) region toward their outskirts. Nearby massive compact galaxies share with high-z compact massive galaxies not only their stellar mass, size, and velocity dispersion but also the shape of their profiles and the mean age of their stellar populations. This makes these singular galaxies unique laboratories to explore the early stages of the formation of massive galaxies.

  4. A massive, quiescent galaxy at a redshift of 3.717.

    PubMed

    Glazebrook, Karl; Schreiber, Corentin; Labbé, Ivo; Nanayakkara, Themiya; Kacprzak, Glenn G; Oesch, Pascal A; Papovich, Casey; Spitler, Lee R; Straatman, Caroline M S; Tran, Kim-Vy H; Yuan, Tiantian

    2017-04-05

    Finding massive galaxies that stopped forming stars in the early Universe presents an observational challenge because their rest-frame ultraviolet emission is negligible and they can only be reliably identified by extremely deep near-infrared surveys. These surveys have revealed the presence of massive, quiescent early-type galaxies appearing as early as redshift z ≈ 2, an epoch three billion years after the Big Bang. Their age and formation processes have now been explained by an improved generation of galaxy-formation models, in which they form rapidly at z ≈ 3-4, consistent with the typical masses and ages derived from their observations. Deeper surveys have reported evidence for populations of massive, quiescent galaxies at even higher redshifts and earlier times, using coarsely sampled photometry. However, these early, massive, quiescent galaxies are not predicted by the latest generation of theoretical models. Here we report the spectroscopic confirmation of one such galaxy at redshift z = 3.717, with a stellar mass of 1.7 × 10(11) solar masses. We derive its age to be nearly half the age of the Universe at this redshift and the absorption line spectrum shows no current star formation. These observations demonstrate that the galaxy must have formed the majority of its stars quickly, within the first billion years of cosmic history in a short, extreme starburst. This ancestral starburst appears similar to those being found by submillimetre-wavelength surveys. The early formation of such massive systems implies that our picture of early galaxy assembly requires substantial revision.

  5. A massive, quiescent galaxy at a redshift of 3.717

    NASA Astrophysics Data System (ADS)

    Glazebrook, Karl; Schreiber, Corentin; Labbé, Ivo; Nanayakkara, Themiya; Kacprzak, Glenn G.; Oesch, Pascal A.; Papovich, Casey; Spitler, Lee R.; Straatman, Caroline M. S.; Tran, Kim-Vy H.; Yuan, Tiantian

    2017-04-01

    Finding massive galaxies that stopped forming stars in the early Universe presents an observational challenge because their rest-frame ultraviolet emission is negligible and they can only be reliably identified by extremely deep near-infrared surveys. These surveys have revealed the presence of massive, quiescent early-type galaxies appearing as early as redshift z ≈ 2, an epoch three billion years after the Big Bang. Their age and formation processes have now been explained by an improved generation of galaxy-formation models, in which they form rapidly at z ≈ 3–4, consistent with the typical masses and ages derived from their observations. Deeper surveys have reported evidence for populations of massive, quiescent galaxies at even higher redshifts and earlier times, using coarsely sampled photometry. However, these early, massive, quiescent galaxies are not predicted by the latest generation of theoretical models. Here we report the spectroscopic confirmation of one such galaxy at redshift z = 3.717, with a stellar mass of 1.7 × 1011 solar masses. We derive its age to be nearly half the age of the Universe at this redshift and the absorption line spectrum shows no current star formation. These observations demonstrate that the galaxy must have formed the majority of its stars quickly, within the first billion years of cosmic history in a short, extreme starburst. This ancestral starburst appears similar to those being found by submillimetre-wavelength surveys. The early formation of such massive systems implies that our picture of early galaxy assembly requires substantial revision.

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

    SciTech Connect

    Trujillo, Ignacio; Vazdekis, Alexandre; Balcells, Marc; Sánchez-Blázquez, Patricia

    2014-01-10

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

  7. Chemical abundances of massive stars in Local Group galaxies

    NASA Astrophysics Data System (ADS)

    Venn, Kim A.; Kaufer, Andreas; Tolstoy, Eline; Kudritzki, Rolf-Peter; Przybilla, Norbert; Smartt, Stephen J.; Lennon, Daniel J.

    The relative abundances of elements in galaxies can provide valuable information on the stellar and chemical evolution of a galaxy. While nebulae can provide abundances for a variety of light elements, stars are the only way to directly determine the abundances of iron-group and s-process and r-process elements in a galaxy. The new 8m and 10m class telescopes and high-efficiency spectrographs now make high-quality spectral observations of bright supergiants possible in dwarf galaxies in the Local Group. We have been concentrating on elemental abundances in the metal-poor dwarf irregular galaxies, NGC 6822, WLM, Sextants A, and GR 8. Comparing abundance ratios to those predicted from their star formation histories, determined from color-magnitude diagrams, and comparing those ratios between these galaxies can give us new insights into the evolution of these dwarf irregular galaxies. Iron-group abundances also allow us to examine the metallicities of the stars in these galaxies directly, which affects their inferred mass loss rates and predicted stellar evolution properties.

  8. Further evidence for large central mass-to-light ratios in massive early-type galaxies

    NASA Astrophysics Data System (ADS)

    Corsini, E. M.; Wegner, G. A.; Thomas, J.; Saglia, R. P.; Bender, R.; Pu, S. B.

    2013-07-01

    We studied the stellar populations, distribution of dark matter, and dynamical structure of a sample of 25 early-type galaxies in the Coma and Abell~262 clusters. We derived dynamical mass-to-light ratios and dark matter densities from orbit-based dynamical models, complemented by the ages, metallicities, and α-element abundances of the galaxies from single stellar population models. Most of the galaxies have a significant detection of dark matter and their halos are about 10 times denser than in spirals of the same stellar mass. Calibrating dark matter densities to cosmological simulations we find assembly redshifts z DM ~ 1-3. The dynamical mass that follows the light is larger than expected for a Kroupa stellar initial mass function, especially in galaxies with high velocity dispersion σeff inside the effective radius r eff. We now have 5 of 25 galaxies where mass follows light to 1-3 r eff, the dynamical mass-to-light ratio of all the mass that follows the light is large (~ 8-10 in the Kron-Cousins R band), the dark matter fraction is negligible to 1-3 r eff. This could indicate a `massive' initial mass function in massive early-type galaxies. Alternatively, some of the dark matter in massive galaxies could follow the light very closely suggesting a significant degeneracy between luminous and dark matter.

  9. Evidence for HI replenishment in massive galaxies through gas accretion from the cosmic web

    NASA Astrophysics Data System (ADS)

    Kleiner, Dane; Pimbblet, Kevin A.; Heath Jones, D.; Koribalski, Bärbel S.; Serra, Paolo

    2016-12-01

    We examine the HI -to-stellar mass ratio (HI fraction) for galaxies near filament backbones within the nearby Universe (d < 181 Mpc). This work uses the 6 degree Field Galaxy Survey (6dFGS) and the Discrete Persistent Structures Extractor (DisPerSE) to define the filamentary structure of the local cosmic web. HI spectral stacking of HI Parkes All Sky Survey (HIPASS) observations yield the HI fraction for filament galaxies and a field control sample. The HI fraction is measured for different stellar masses and 5th nearest neighbour projected densities (Σ5) to disentangle what influences cold gas in galaxies. For galaxies with stellar masses log(M⋆) ≤ 11 M⊙ in projected densities 0 ≤ Σ5 < 3 galaxies Mpc-2, all HI fractions of galaxies near filaments are statistically indistinguishable from the control sample. Galaxies with stellar masses log(M⋆) ≥ 11 M⊙ have a systematically higher HI fraction near filaments than the control sample. The greatest difference is 0.75 dex, which is 5.5σ difference at mean projected densities of 1.45 galaxies Mpc-2. We suggest that this is evidence for massive galaxies accreting cold gas from the intra-filament medium which can replenish some HI gas. This supports cold mode accretion where filament galaxies with a large gravitational potential can draw gas from the large scale structure.

  10. The Black Hole Safari: Big Game Hunting in 30+ Massive Galaxies

    NASA Astrophysics Data System (ADS)

    McConnell, Nicholas J.; Ma, Chung-Pei; Janish, Ryan; Gebhardt, Karl; Lauer, Tod R.; Graham, James R.

    2015-01-01

    The current census of the most massive black holes in the local universe turns up an odd variety of galaxy hosts: central galaxies in rich clusters, second- or lower-ranked cluster members, and compact relics from the early universe. More extensive campaigns are required to explore the number density and environmental distribution of these monsters. Over the past three years we have collected a large set of stellar kinematic data with sufficient resolution to detect the gravitational signatures of supermassive black holes with MBH > 109 MSun. This Black Hole Safari targets enormous galaxies at the centers of nearby galaxy clusters, as well as their similarly luminous counterparts in weaker galaxy groups. To date we have observed more than 30 early-type galaxies with integral-field spectrographs on the Keck, Gemini North, and Gemini South telescopes. Here I present preliminary stellar kinematics from 10 objects.

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

    PubMed

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

    2016-12-07

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  13. 3D Spectroscopy Unveils Massive Galaxy Formation Modes at High-z

    NASA Astrophysics Data System (ADS)

    Buitrago, F.; Conselice, C. J.; Epinat, B.; Bedregal, A. G.; Trujillo, I.; Grützbauch, R.

    Massive (stellar mass ≥ 1011 M ⊙) galaxies at high redshift (z ≥ 1. 5) remain mysterious objects. Their extremely small sizes (effective radii of 1 - 2 kpc) make them as dense as globular clusters, whereas in the present day Universe similar mass systems are large with old and metal-rich stellar populations. In order to explore this development, we present near-IR IFU observations with SINFONI@VLT for ten massive galaxies at z ˜ 1. 4 solely selected by their high stellar mass which allows us to retrieve velocity dispersions, kinematic maps and dynamical masses. We join this with imaging from the GOODS NICMOS Survey (GNS), which was carried out by our group, and which is the largest sample of massive galaxies (80 objects) at high redshift (1. 7 < z < 3) to date. With these data we show how their morphology changes, possibly as a result of minor merging events also seen in the kinematics.

  14. A CANDIDATE MASSIVE BLACK HOLE IN THE LOW-METALLICITY DWARF GALAXY PAIR MRK 709

    SciTech Connect

    Reines, Amy E.; Condon, James J.; Plotkin, Richard M.; Russell, Thomas D.; Mezcua, Mar; Sivakoff, Gregory R.; Johnson, Kelsey E.

    2014-06-01

    The incidence and properties of present-day dwarf galaxies hosting massive black holes (BHs) can provide important constraints on the origin of high-redshift BH seeds. Here we present high-resolution X-ray and radio observations of the low-metallicity, star-forming, dwarf-galaxy system Mrk 709 with the Chandra X-ray Observatory and the Karl G. Jansky Very Large Array. These data reveal spatially coincident hard X-ray and radio point sources with luminosities suggesting the presence of an accreting massive BH (M {sub BH} ∼ 10{sup 5-7} M {sub ☉}). Based on imaging from the Sloan Digital Sky Survey (SDSS), we find that Mrk 709 consists of a pair of compact dwarf galaxies that appear to be interacting with one another. The position of the candidate massive BH is consistent with the optical center of the southern galaxy (Mrk 709 S), while no evidence for an active BH is seen in the northern galaxy (Mrk 709 N). We derive stellar masses of M {sub *} ∼ 2.5 × 10{sup 9} M {sub ☉} and M {sub *} ∼ 1.1 × 10{sup 9} M {sub ☉} for Mrk 709 S and Mrk 709 N, respectively, and present an analysis of the SDSS spectrum of the BH host Mrk 709 S. At a metallicity of just ∼10% solar, Mrk 709 is among the most metal-poor galaxies with evidence for an active galactic nucleus. Moreover, this discovery adds to the growing body of evidence that massive BHs can form in dwarf galaxies and that deep, high-resolution X-ray and radio observations are ideally suited to reveal accreting massive BHs hidden at optical wavelengths.

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

    PubMed

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

    2011-02-03

    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.

  16. Strangers in Our Midst: Massive, Evolved, Highly-obscured Galaxies at z > 1

    NASA Astrophysics Data System (ADS)

    Brammer, Gabriel; 3D-HST Survey Team

    2015-01-01

    Among the most massive galaxies at z > 1, we have uncovered a significant population of galaxies with unique SEDs that are best fit with highly-obscured evolved stellar populations (log M > 11, Av > 2, age > 1 Gyr). These are not galaxies at the detection limit or galaxies with the most extreme optical-IR colors: they have always been lurking in IR-selected photometric surveys but with their redshifts significantly overestimated and subsequently-biased derived stellar population properties. Characterizing this population has previously been impossible even with medium-band near-IR photometry due to strong degeneracies between photometric redshifts and SED shapes, which we can now critically break with robust emission-line redshifts obtained from the 3D-HST grism survey (H-alpha and [OIII] at 1 < z < 2). Understanding this population is imperative for interpreting the evolution of the high-mass end of the galaxy stellar mass function. Intriguingly, these galaxies could represent an evolutionary bridge between dusty starbursts and relatively unobscured quiescent galaxies, both of which are found among massive galaxies at z > 1 but with the latter dominating at lower redshifts.

  17. An actively accreting massive black hole in the dwarf starburst galaxy Henize2-10

    NASA Astrophysics Data System (ADS)

    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 Henize2-10 (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 Henize2-10 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 Henize2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids.

  18. Relaxation of hot and massive tracers using numerical solutions of the Boltzmann equation

    NASA Astrophysics Data System (ADS)

    Khurana, Saheba; Thachuk, Mark

    2016-03-01

    A numerical method using B-splines is used to solve the linear Boltzmann equation describing the energy relaxation of massive tracer particles moving through a dilute bath gas. The smooth and rough hard sphere and Maxwell molecule models are used with a variety of mass ratios and initial energies to test the capability of the numerical method. Massive tracers are initialized with energies typically found in energy loss experiments in mass spectrometry using biomolecules. The method is also used to examine the applicability of known expressions for the kinetic energy decay from the Fokker-Planck equation for the Rayleigh gas, where we find that results are generally good provided that the initial energy is properly bounded. Otherwise, the energy decay is not constant and a more complex behaviour occurs. The validity of analytical expressions for drag coefficients for spherical particles under specular and diffuse scattering is also tested. We find such expressions are generally good for hard spheres but cannot account, as expected, for the softer repulsive walls of the Maxwell (and real) molecules. Overall, the numerical method performed well even when tracers more than 400 times as massive as the bath were initialized with energies very far from equilibrium. This is a range of applicability beyond many of the standard methods for solving the Boltzmann equation.

  19. Relaxation of hot and massive tracers using numerical solutions of the Boltzmann equation.

    PubMed

    Khurana, Saheba; Thachuk, Mark

    2016-03-14

    A numerical method using B-splines is used to solve the linear Boltzmann equation describing the energy relaxation of massive tracer particles moving through a dilute bath gas. The smooth and rough hard sphere and Maxwell molecule models are used with a variety of mass ratios and initial energies to test the capability of the numerical method. Massive tracers are initialized with energies typically found in energy loss experiments in mass spectrometry using biomolecules. The method is also used to examine the applicability of known expressions for the kinetic energy decay from the Fokker-Planck equation for the Rayleigh gas, where we find that results are generally good provided that the initial energy is properly bounded. Otherwise, the energy decay is not constant and a more complex behaviour occurs. The validity of analytical expressions for drag coefficients for spherical particles under specular and diffuse scattering is also tested. We find such expressions are generally good for hard spheres but cannot account, as expected, for the softer repulsive walls of the Maxwell (and real) molecules. Overall, the numerical method performed well even when tracers more than 400 times as massive as the bath were initialized with energies very far from equilibrium. This is a range of applicability beyond many of the standard methods for solving the Boltzmann equation.

  20. Constraints on the evolutionary mechanisms of massive galaxies since z ∼ 1 from their velocity dispersions

    NASA Astrophysics Data System (ADS)

    Peralta de Arriba, L.; Balcells, M.; Trujillo, I.; Falcón-Barroso, J.; Tapia, T.; Cardiel, N.; Gallego, J.; Guzmán, R.; Hempel, A.; Martín-Navarro, I.; Pérez-González, P. G.; Sánchez-Bláquez, P.

    2015-10-01

    Several authors have reported that the dynamical masses of massive compact galaxies (M* ≳ 1011 M⊙, re ∼ 1 kpc), computed as Mdyn = 5.0 σe2 re/G, are lower than their stellar masses M*. In a previous study from our group, the discrepancy is interpreted as a breakdown of the assumption of homology that underlie the Mdyn determinations. Here, we present new spectroscopy of six redshift z ≈ 1.0 massive compact ellipticals from the Extended Groth Strip, obtained with the 10.4 m Gran Telescopio Canarias. We obtain velocity dispersions in the range 161-340 km s-1. As found by previous studies of massive compact galaxies, our velocity dispersions are lower than the virial expectation, and all of our galaxies show Mdyn < M* (assuming a Salpeter initial mass function). Adding data from the literature, we build a sample covering a range of stellar masses and compactness in a narrow redshift range z ≈ 1.0. This allows us to exclude systematic effects on the data and evolutionary effects on the galaxy population, which could have affected previous studies. We confirm that mass discrepancy scales with galaxy compactness. We use the stellar mass plane (M*, σe, re) populated by our sample to constrain a generic evolution mechanism. We find that the simulations of the growth of massive ellipticals due to mergers agree with our constraints and discard the assumption of homology.

  1. THE STRUCTURE OF MASSIVE QUIESCENT GALAXIES AT Z {approx} 3 IN THE CANDELS-COSMOS FIELD

    SciTech Connect

    Fan Lulu; Chen Yang; Pan Zhizheng; Lv Xuanyi; Li Jinrong; Lin Lin; Kong Xu; Fang Guanwen

    2013-07-10

    In this Letter, we use a two-color (J - L) versus (V - J) selection criterion to search massive quiescent galaxy (QG) candidates at 2.5 {<=} z {<=} 4.0 in the CANDELS-COSMOS field. We construct an H{sub F160W}-selected catalog and complement it with public auxiliary data. We finally obtain 19 passive VJL-selected (hereafter pVJL) galaxies as the possible massive QG candidates at z {approx} 3 by several constrains. We find the sizes of our pVJL galaxies are on average three to four times smaller than those of local early-type galaxies (ETGs) with analogous stellar mass. The compact size of these z {approx} 3 galaxies can be modeled by assuming their formation at z{sub form} {approx} 4-6 according to the dissipative collapse of baryons. Up to z < 4, the mass-normalized size evolution can be described by r{sub e} {proportional_to}(1 + z){sup -1.0}. Low Sersic index and axis ratio, with median values n {approx}1.5 and b/a {approx} 0.65, respectively, indicate that most of the pVJL galaxies are disk-dominated. Despite large uncertainty, the inner region of the median mass profile of our pVJL galaxies is similar to those of QGs at 0.5 < z < 2.5 and local ETGs. It indicates that local massive ETGs have been formed according to an inside-out scenario: the compact galaxies at high redshift make up the cores of local massive ETGs and then build up the outskirts according to dissipationless minor mergers.

  2. Photometric Study of Massive Evolved Galaxies in the CANDELS GOODS-S at z>3

    NASA Astrophysics Data System (ADS)

    Nayyeri, Hooshang; Mobasher, B.; Ferguson, H. C.; Wiklind, T.; Hemmati, S.; De Barros, S.; Fontana, A.; Dahlen, T.; Koekemoer, A. M.

    2014-01-01

    According to the hierarchical models, galaxies assemble their mass through time with the most massive and evolved systems found in the more recent times and in the most massive dark matter halos. Understanding the evolution of mass assembly with cosmic time plays a central role in observational astronomy. Here, we use the very deep near Infra-red HST/WFC3 observations by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) to study passively evolving, old and massive systems at high redshifts. For this we utilize the pronounced Balmer Break (an age dependent diagnostic at rest-frame 3648Å) in post-starburst galaxies to devise a Balmer Break Galaxy (BBG) selection. We use the CANDELS WFC3 1.6 μm selected catalog in the GOODS-S, generated with TFIT algorithm suitable for mixed resolution data sets, to select the candidates. We identified 24 sources as candidates for evolved systems in the redshift 3.5galaxies show that the most noticeable source of contamination is from dusty starburst galaxies that can produce similar red colors. Fitting the spectral energy distribution (SED) of the candidate galaxies with a well-constructed library of model galaxies show that the candidate galaxies have estimated ages older than 100 Myr and masses larger than 10^10 M_Sun consistent with being old and massive systems. Forty percent of the passive candidates are also selected by the LBG selection indicating presence of residual star formation in the post-starburst population. Given the age and the current redshift, some of these systems must have formed bulk of their mass only a few hundred million years after the Big Bang.

  3. Evidence for Reduced Specific Star Formation Rates in the Centers of Massive Galaxies at z = 4

    NASA Astrophysics Data System (ADS)

    Jung, Intae; Finkelstein, Steven L.; Song, Mimi; Dickinson, Mark; Dekel, Avishai; Ferguson, Henry C.; Fontana, Adriano; Koekemoer, Anton M.; Lu, Yu; Mobasher, Bahram; Papovich, Casey; Ryan, Russell E., Jr.; Salmon, Brett; Straughn, Amber N.

    2017-01-01

    We perform the first spatially resolved stellar population study of galaxies in the early universe (z = 3.5–6.5), utilizing the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey imaging data set over the GOODS-S field. We select a sample of 418 bright and extended galaxies at z = 3.5–6.5 from a parent sample of ∼8000 photometric-redshift-selected galaxies from Finkelstein et al. We first examine galaxies at 3.5 ≲ z ≲ 4.0 using additional deep K-band survey data from the HAWK-I UDS and GOODS Survey which covers the 4000 Å break at these redshifts. We measure the stellar mass, star formation rate, and dust extinction for galaxy inner and outer regions via spatially resolved spectral energy distribution fitting based on a Markov Chain Monte Carlo algorithm. By comparing specific star formation rates (sSFRs) between inner and outer parts of the galaxies we find that the majority of galaxies with high central mass densities show evidence for a preferentially lower sSFR in their centers than in their outer regions, indicative of reduced sSFRs in their central regions. We also study galaxies at z ∼ 5 and 6 (here limited to high spatial resolution in the rest-frame ultraviolet only), finding that they show sSFRs which are generally independent of radial distance from the center of the galaxies. This indicates that stars are formed uniformly at all radii in massive galaxies at z ∼ 5–6, contrary to massive galaxies at z ≲ 4.

  4. Hot, Massive Stars in the Extremely Metal-Poor Galaxy, I Zw 18

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Malumuth, Eliot M.

    2010-01-01

    The carbon-enhanced metal-poor galaxy, I Zw 18, is the Rosetta Stone for understanding galaxies in the early universe by providing constraints on the IMF of massive stars, the role of galaxies in reionization of the universe, mixing of newly synthesized material in the ISM, and gamma-ray bursts at low metallicity, and on the earliest generations of stars producing the observed abundance pattern. We describe these constraints as derived from analyses of HST/COS spectra of I Zw 18 including stellar atmosphere analysis and photo-ionization modeling of both the emission and absorption spectra of the nebular material and interstellar medium.

  5. A Snapshot Survey of The Most Massive Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald

    2007-07-01

    We propose the continuation of our highly successful SNAPshot survey of a sample of 125 very X-ray luminous clusters in the redshift range 0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14 and Cycle15 these systems frequently exhibit strong gravitational lensing as well as spectacular examples of violent galaxy interactions. The proposed observations will provide important constraints on the cluster mass distributions, the physical nature of galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. All of our primary science goals require only the detection and characterisation of high-surface-brightness features and are thus achievable even at the reduced sensitivity of WFPC2. Because of their high redshift and thus compact angular scale our target clusters are less adversely affected by the smaller field of view of WFPC2 than more nearby systems. Acknowledging the broad community interest in this sample we waive our data rights for these observations. Due to a clerical error at STScI our approved Cycle15 SNAP program was barred from execution for 3 months and only 6 observations have been performed to date - reinstating this SNAP at Cycle16 priority is of paramount importance to reach meaningful statistics.

  6. Gravitational Heating Helps Make Massive Galaxies Red and Dead

    NASA Astrophysics Data System (ADS)

    Johansson, Peter H.; Naab, Thorsten; Ostriker, Jeremiah P.

    2009-05-01

    We study the thermal formation history of four simulated galaxies that were shown by Naab et al. to reproduce a number of observed properties of elliptical galaxies. The temperature of the gas in the galaxies is steadily increasing with decreasing redshift, although much of the gas has a cooling time shorter than the Hubble time. The gas is being heated and kept hot by gravitational heating processes through the release of potential energy from infalling stellar clumps. The energy is dissipated in supersonic collisions of infalling gas lumps with the ambient gas and through the dynamical capturing of satellite systems causing gravitational wakes that transfer energy to the surrounding gas. Furthermore, dynamical friction from the infalling clumps pushes out dark matter (DM), lowering the central DM density by up to a factor of 2 from z = 3 to z = 0. In galaxies in which the late formation history (z lsim 2) is dominated by minor merging and accretion, the energy released (E ~ 5 × 1059 erg) from gravitational feedback is sufficient to form red and dead elliptical galaxies by z ~ 1 even in the absence of supernova and AGN feedback.

  7. Cold streams in early massive hot haloes as the main mode of galaxy formation.

    PubMed

    Dekel, A; Birnboim, Y; Engel, G; Freundlich, J; Goerdt, T; Mumcuoglu, M; Neistein, E; Pichon, C; Teyssier, R; Zinger, E

    2009-01-22

    Massive galaxies in the young Universe, ten billion years ago, formed stars at surprising intensities. Although this is commonly attributed to violent mergers, the properties of many of these galaxies are incompatible with such events, showing gas-rich, clumpy, extended rotating disks not dominated by spheroids. Cosmological simulations and clustering theory are used to explore how these galaxies acquired their gas. Here we report that they are 'stream-fed galaxies', formed from steady, narrow, cold gas streams that penetrate the shock-heated media of massive dark matter haloes. A comparison with the observed abundance of star-forming galaxies implies that most of the input gas must rapidly convert to stars. One-third of the stream mass is in gas clumps leading to mergers of mass ratio greater than 1:10, and the rest is in smoother flows. With a merger duty cycle of 0.1, three-quarters of the galaxies forming stars at a given rate are fed by smooth streams. The rarer, submillimetre galaxies that form stars even more intensely are largely merger-induced starbursts. Unlike destructive mergers, the streams are likely to keep the rotating disk configuration intact, although turbulent and broken into giant star-forming clumps that merge into a central spheroid. This stream-driven scenario for the formation of discs and spheroids is an alternative to the merger picture.

  8. Global and radial variations in the efficiency of massive star formation among galaxies

    NASA Technical Reports Server (NTRS)

    Allen, Lori E.; Young, Judith S.

    1990-01-01

    In order to determine the regions within galaxies which give rise to the most efficient star formation and to test the hypothesis that galaxies with high infrared luminosities per unit molecular mass are efficiently producing high mass stars, researchers have undertaken an H alpha imaging survey in galaxies whose CO distributions have been measured as part of the Five College Radio Astronomy Observatory (FCRAO) Extragalactic CO Survey. From these images researchers have derived global H alpha fluxes and distributions for comparison with far infrared radiation (FIR) fluxes and CO fluxes and distributions. Here, researchers present results on the global massive star formation efficiency (SFE = L sub H sub alpha/M(H2)) as a function of morphological type and environment, and on the radial distribution of the SFE within both peculiar and isolated galaxies. On the basis of comparison of the global L sub H sub alpha/M(H2) and L sub FIR/M(H2) for 111 galaxies, researchers conclude that environment rather than morphological type has the strongest effect on the global efficiency of massive star formation. Based on their study of a small sample, they find that the largest radial gradients are observed in the interacting/peculiar galaxies, indicating that environment affects the star formation efficiency within galaxies as well.

  9. Unveiling the Most Massive Galaxies in the Universe: IRAC Mapping of the NMBSII/CFHTLS Fields

    NASA Astrophysics Data System (ADS)

    Marchesini, Danilo; Muzzin, Adam; van Dokkum, Pieter; Wake, David; Franx, Marijn; Marsan, Cemile; Rudnick, Gregory; Brammer, Gabriel; Stefanon, Mauro; Lundgren, Britt; Whitaker, Katherine; Tal, Tomer; Labbe, Ivo; Bezanson, Rachel; Weigel, Catherine

    2013-10-01

    Observations of massive galaxies and their redshift evolution place strong constraints on the physical processes of galaxy formation. Although substantial data have been collected on galaxies with masses LogM~11.2 out to z~4-5 from the recent myriad of ground-based wide-field NIR surveys, very little is known about the evolution of the most massive (LogM>11.4) galaxies in the universe. At the tip of the Schechter function, their space density is estimated to be 30x lower than LogM=11 galaxies and hence only a few have been found, even in the widest-field surveys. We recently undertook the NMBS-II survey, a medium-deep wide-field (4.7 deg^2) NIR medium-band survey designed to accurately characterize the stellar mass function, number density, stellar populations, and clustering properties of the most massive galaxies out to z=3. The primary survey fields of the NMBS-II are the CFHTLS-deep fields; however, presently only 60% of these fields have IRAC coverage. We propose to complete the IRAC coverage of the NMBS-II. The IRAC data are essential for accurately measuring photometric redshifts and stellar masses of the high-redshift population. IRAC data are critical for constructing the UVJ diagram, which has become the de-facto method for differentiating red dusty star-forming from red quiescent galaxies. The proposed observations will allow us to construct a sample of ~300 ultra-massive (LogM>11.4) galaxies at 1.5galaxies. Because these massive galaxies are expected to be one of the most clustered populations, and thus greatly affected by cosmic variance, maximal area and number of independent sight-lines are needed for robust clustering measurements. The proposed IRAC survey will more than double the sight-lines allowing us to exploit the full NMBS-II area. We waive our proprietary data-rights period, committing to publicly release the fully reduced IRAC

  10. Stellar Mass Functions of Galaxies At 4 < z < 7 from an IRAC-selected Sample in Cosmos/Ultravista: Limits on the Abundance of Very Massive Galaxies

    NASA Astrophysics Data System (ADS)

    Stefanon, Mauro; Marchesini, Danilo; Muzzin, Adam; Brammer, Gabriel; Dunlop, James S.; Franx, Marijin; Fynbo, Johan P. U.; Labbé, Ivo; Milvang-Jensen, Bo; van Dokkum, Pieter G.

    2015-04-01

    We build a Spitzer IRAC-complete catalog of objects complementing the Ks-band selected UltraVISTA catalog with objects detected in IRAC only. To identify massive (log ({{M}*}/{{M}⊙ })\\gt 11) galaxies at 4\\lt z\\lt 7, we consider the systematic effects on photometric redshift measurements from the introduction of an old and dusty template and of a bayesian prior on luminosity, as well as the systematic effects from different star formation histories (SFHs) and from nebular emission lines in estimated stellar population properties. Our results are most affected by the luminosity prior, while nebular lines and SFHs marginally increase the measurement dispersion; the samples include 52 to 382 galaxies, depending on the adopted configuration. Using these results we investigate, for the first time, the evolution of the massive end of the stellar mass functions (SMFs) at 4\\lt z\\lt 7. Given the rarity of massive galaxies at these redshifts, cosmic variance and Poisson noise dominate the total error budget. The SMFs obtained excluding the luminosity prior show no evolution from z˜ 6.5 to z˜ 3.5, indicating that massive galaxies could already be present at early epochs. The luminosity prior reduces the number of z\\gt 4 massive galaxies by 83%, implying a rapid growth of massive galaxies in the first 1.5 Gyr of cosmic history. The stellar-mass complete sample includes one candidate of a very massive (log ({{M}*}/{{M}⊙ })˜ 11.5), quiescent galaxy at z˜ 5.4 with MIPS 24 μ m detection, suggesting the presence of an obscured active galactic nucleus. Finally, we show that the observed number of 4\\lt z\\lt 7 massive galaxies matches the number of massive galaxies at 3\\lt z\\lt 6 predicted by current galaxy formation models.

  11. The many assembly histories of massive void galaxies as revealed by integral field spectroscopy

    NASA Astrophysics Data System (ADS)

    Fraser-McKelvie, Amelia; Pimbblet, Kevin A.; Penny, Samantha J.; Brown, Michael J. I.

    2016-06-01

    We present the first detailed integral field spectroscopy study of nine central void galaxies with M⋆ > 1010 M⊙ using the Wide Field Spectrograph to determine how a range of assembly histories manifest themselves in the current day Universe. While the majority of these galaxies are evolving secularly, we find a range of morphologies, merger histories and stellar population distributions, though similarly low Hα-derived star formation rates (<1 M⊙ yr-1). Two of our nine galaxies host active galactic nuclei, and two have kinematic disruptions to their gas that are not seen in their stellar component. Most massive void galaxies are red and discy, which we attribute to a lack of major mergers. Some have disturbed morphologies and may be in the process of evolving to early-type thanks to ongoing minor mergers at present times, likely fed by tendrils leading off filaments. The diversity in our small galaxy sample, despite being of similar mass and environment means that these galaxies are still assembling at present day, with minor mergers playing an important role in their evolution. We compare our sample to a mass and magnitude-matched sample of field galaxies, using data from the Sydney-AAO Multi-object Integral field spectrograph galaxy survey. We find that despite environmental differences, galaxies of mass M⋆ > 1010 M⊙ have similarly low star formation rates (<3 M⊙ yr-1). The lack of distinction between the star formation rates of the void and field environments points to quenching of massive galaxies being a largely mass-related effect.

  12. A massive young cluster in the Outer Galaxy

    NASA Astrophysics Data System (ADS)

    Negueruela, I.; Monguió, M.; Marco, A.; González-Fernández, C.; Dorda, R.

    2017-03-01

    We present the results of our investigation of the reddened open cluster Berkeley 51. We find an important population of yellow and red supergiant stars. Multi-object spectroscopy with GTC/OSIRIS reveals a population of B-type stars, with a main-sequence extending up to B3 V. With a combination of spectroscopy and photometry, we determine an age around 35 Ma and a distance probably compatible with the Perseus Arm in this direction. The large population of supergiants suggests a rather massive cluster, confirming that this kind of young massive clusters are much more frequent in the Milky Way than envisaged only a few years ago.

  13. Charting the evolution of the ages and metallicities of massive galaxies since z = 0.7

    SciTech Connect

    Gallazzi, Anna; Zibetti, Stefano; Bell, Eric F.; Brinchmann, Jarle; Kelson, Daniel D.

    2014-06-10

    Detailed studies of the stellar populations of intermediate-redshift galaxies can shed light onto the processes responsible for the growth of the massive galaxy population in the last 8 billion years. We here take a step toward this goal by means of deep, multiobject rest-frame optical spectroscopy, performed with the Inamori Magellan Areal Camera and Spectrograph on the Magellan telescope, of a sample of ∼70 galaxies in the Extended Chandra Deep Field South survey with redshift 0.65 ≤ z ≤ 0.75, apparent R > 22.7 mag{sub Vega}, and stellar mass >10{sup 10} M {sub ☉}. We measure velocity dispersion and stellar absorption features for individual sources. We interpret them by means of a large Monte Carlo library of star formation histories, following the Bayesian approach adopted for previous low redshift studies, and derive constraints on the stellar mass, mean stellar age, and stellar metallicity of these galaxies. We characterize for the first time the relations between stellar age and stellar mass and between stellar metallicity and stellar mass at z ∼ 0.7 for the galaxy population as a whole and for quiescent and star-forming galaxies separately. These relations of increasing age and metallicity with galaxy mass for the galaxy population as a whole have a similar shape as the z ∼ 0.1 analog derived for Sloan Digital Sky Survey galaxies but are shifted by –0.28 dex in age and by –0.13 dex in metallicity, at odds with simple passive evolution. Considering z = 0.7 quiescent galaxies alone, we find that no additional star formation and chemical enrichment are required for them to evolve into the present-day quiescent population. However, other observations require the quiescent population to grow from z = 0.7 to the present day. This growth could be supplied by the quenching of a fraction of z = 0.7 M {sub *} > 10{sup 11} M {sub ☉} star-forming galaxies with metallicities already comparable to those of quiescent galaxies, thus leading to the

  14. The TESIS Project: Revealing Massive Early-Type Galaxies at z > 1

    NASA Astrophysics Data System (ADS)

    Saracco, P.; Longhetti, M.; Severgnini, P.; Della Ceca, R.; Braito, V.; Bender, R.; Drory, N.; Feulner, G.; Hopp, U.; Mannucci, F.; Maraston, C.

    How and when present-day massive early-type galaxies built up and what type of evolution has characterized their growth (star formation and/or merging) still remain open issues. The different competing scenarios of galaxy formation predict much different properties of early-type galaxies at z > 1. The "monolithic" collapse predicts that massive spheroids formed at high redshift (z > 2.5-3) and that their comoving density is constant at z < 2.5-3 since they evolve only in luminosity. On the contrary, in the hierarchical scenario massive spheroids are built up through subsequent mergers reaching their final masses at z < 1.5 [3,5]. As a consequence, massive systems are very rare at z > 1, their comoving density decreases from z = 0 to z ~ 1.5 and they should experience their last burst of star formation at z < 1.5, concurrent with the merging event(s) of their formation. These opposed predicted properties of early-types at z > 1 can be probed observationally once a well defined sample of massive early-types at z > 1 is available. We are constructing such a sample through a dedicated near-IR very low resolution (λ/Δλ≃50) spectroscopic survey (TNG EROs Spectroscopic Identification Survey, TESIS, [6]) of a complete sample of 30 bright (K < 18.5) Extremely Red Objects (EROs).

  15. The assembly of stellar haloes in massive Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Buitrago, F.

    2017-03-01

    Massive (Mstellar >= 5×1010 M⊙) Early-Type Galaxies (ETGs) must build an outer stellar envelope over cosmic time in order to account for their remarkable size evolution. This is similar to what occurs to nearby Late-Type Galaxies (LTGs), which create their stellar haloes out of the debris of lower mass systems. We analysed the outer parts of massive ETGs at z < 1 by exploiting the Hubble Ultra Deep Field imaging. These galaxies store 10-30% of their stellar mass at distances 10 < R/kpc < 50, in contrast to the low percentages (< 5%) found for LTGs. We find evidence for a progressive outskirt development with redshift driven solely via merging.

  16. Galaxy evolution. Quasar quartet embedded in giant nebula reveals rare massive structure in distant universe.

    PubMed

    Hennawi, Joseph F; Prochaska, J Xavier; Cantalupo, Sebastiano; Arrigoni-Battaia, Fabrizio

    2015-05-15

    All galaxies once passed through a hyperluminous quasar phase powered by accretion onto a supermassive black hole. But because these episodes are brief, quasars are rare objects typically separated by cosmological distances. In a survey for Lyman-α emission at redshift z ≈ 2, we discovered a physical association of four quasars embedded in a giant nebula. Located within a substantial overdensity of galaxies, this system is probably the progenitor of a massive galaxy cluster. The chance probability of finding a quadruple quasar is estimated to be ∼10(-7), implying a physical connection between Lyman-α nebulae and the locations of rare protoclusters. Our findings imply that the most massive structures in the distant universe have a tremendous supply (≃10(11) solar masses) of cool dense (volume density ≃ 1 cm(-3)) gas, which is in conflict with current cosmological simulations.

  17. Linking star formation and galaxy kinematics in the massive cluster Abell 2163

    NASA Astrophysics Data System (ADS)

    Menacho, Veronica; Verdugo, Miguel

    2015-02-01

    The origin of the morphology-density relation is still an open question in galaxy evolution. It is most likely driven by the combination of the efficient star formation in the highest peaks of the mass distribution at high-z and the transformation by environmental processes at later times as galaxies fall into more massive halos. To gain additional insights about these processes we study the kinematics, star formation and structural properties of galaxies in Abell 2163 a very massive (~4×1015 M⊙, Holz & Perlmutter 2012) merging cluster at z = 0.2. We use high resolution spectroscopy with VLT/VIMOS to derive rotation curves and dynamical masses for galaxies that show regular kinematics. Galaxies that show irregular rotation are also analysed to study the origin of their distortion. This information is combined with stellar masses and structural parameters obtained from high quality CFHT imaging. From narrow band photometry (2.2m/WFI), centered on the redshifted Hα line, we obtain star formation rates. Although our sample is still small, field and cluster galaxies lie in a similar Tully-Fisher relation as local galaxies. Controlling by additional parameters like SFRs or bulge-to-disk ratio do not affect this result. We find however that ~50% of the cluster galaxies display irregular kinematics in contrast to what is found in the field at similar redshifts (~30%, Böhm et al. 2004) and in agreement with other studies in clusters (e.g. Bösch et al. 2013, Kutdemir et al. 2010) which points out to additional processes operating in clusters that distort the galaxy kinematics.

  18. Massive Star Formation in Early-type(Sa-Sab) Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Hameed, S.

    1999-12-01

    We have conducted an Hα imaging survey of 57 bright, nearby, early-type spiral galaxies. The new Hα images have revealed them to be a heterogeneous class of galaxies with Hα morphologies ranging from filamentary, low luminosity nuclear emission line spirals to what we suspect are compact, luminous nuclear starbursts. Contrary to popular perception, our images have revealed a significant number(15-20%) of Sa-Sab galaxies with massive star formation rates comparable to the most prolifically star forming Sc galaxies. A determination of the Hα morphology and a measure of the Hα luminosity suggests that early-type spirals can be classified into two broad categories. The first category includes galaxies for which the individual HII regions have L(Hα ) < 1039 erg/s. Most of the category 1 galaxies appear to be morphologically undisturbed, but show a wide diversity in nuclear Hα properties. The second category includes galaxies which have at least one HII region in the disk with L(Hα ) >= 1039 erg/s. All category 2 galaxies show morphological peculiarities, such as tidal tails, which suggests that the anomalously luminous HII regions may have formed as a result of a recent interaction. We have also determined HII region luminosity functions for a subset of our sample and find that the shape of the HII region LF is different when a giant HII region is present compared to a galaxy which contains only HII regions of modest luminosity. The difference may point to corresponding differences in massive star formation triggering mechanisms.

  19. JELLYFISH: EVIDENCE OF EXTREME RAM-PRESSURE STRIPPING IN MASSIVE GALAXY CLUSTERS

    SciTech Connect

    Ebeling, H.; Stephenson, L. N.; Edge, A. C.

    2014-02-01

    Ram-pressure stripping by the gaseous intracluster medium has been proposed as the dominant physical mechanism driving the rapid evolution of galaxies in dense environments. Detailed studies of this process have, however, largely been limited to relatively modest examples affecting only the outermost gas layers of galaxies in nearby and/or low-mass galaxy clusters. We here present results from our search for extreme cases of gas-galaxy interactions in much more massive, X-ray selected clusters at z > 0.3. Using Hubble Space Telescope snapshots in the F606W and F814W passbands, we have discovered dramatic evidence of ram-pressure stripping in which copious amounts of gas are first shock compressed and then removed from galaxies falling into the cluster. Vigorous starbursts triggered by this process across the galaxy-gas interface and in the debris trail cause these galaxies to temporarily become some of the brightest cluster members in the F606W passband, capable of outshining even the Brightest Cluster Galaxy. Based on the spatial distribution and orientation of systems viewed nearly edge-on in our survey, we speculate that infall at large impact parameter gives rise to particularly long-lasting stripping events. Our sample of six spectacular examples identified in clusters from the Massive Cluster Survey, all featuring M {sub F606W} < –21 mag, doubles the number of such systems presently known at z > 0.2 and facilitates detailed quantitative studies of the most violent galaxy evolution in clusters.

  20. Jellyfish: Evidence of Extreme Ram-pressure Stripping in Massive Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Ebeling, H.; Stephenson, L. N.; Edge, A. C.

    2014-02-01

    Ram-pressure stripping by the gaseous intracluster medium has been proposed as the dominant physical mechanism driving the rapid evolution of galaxies in dense environments. Detailed studies of this process have, however, largely been limited to relatively modest examples affecting only the outermost gas layers of galaxies in nearby and/or low-mass galaxy clusters. We here present results from our search for extreme cases of gas-galaxy interactions in much more massive, X-ray selected clusters at z > 0.3. Using Hubble Space Telescope snapshots in the F606W and F814W passbands, we have discovered dramatic evidence of ram-pressure stripping in which copious amounts of gas are first shock compressed and then removed from galaxies falling into the cluster. Vigorous starbursts triggered by this process across the galaxy-gas interface and in the debris trail cause these galaxies to temporarily become some of the brightest cluster members in the F606W passband, capable of outshining even the Brightest Cluster Galaxy. Based on the spatial distribution and orientation of systems viewed nearly edge-on in our survey, we speculate that infall at large impact parameter gives rise to particularly long-lasting stripping events. Our sample of six spectacular examples identified in clusters from the Massive Cluster Survey, all featuring M F606W < -21 mag, doubles the number of such systems presently known at z > 0.2 and facilitates detailed quantitative studies of the most violent galaxy evolution in clusters. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs GO-10491, -10875, -12166, and -12884.

  1. An extremely young massive clump forming by gravitational collapse in a primordial galaxy.

    PubMed

    Zanella, A; Daddi, E; Le Floc'h, E; Bournaud, F; Gobat, R; Valentino, F; Strazzullo, V; Cibinel, A; Onodera, M; Perret, V; Renaud, F; Vignali, C

    2015-05-07

    When cosmic star formation history reaches a peak (at about redshift z ≈ 2), galaxies vigorously fed by cosmic reservoirs are dominated by gas and contain massive star-forming clumps, which are thought to form by violent gravitational instabilities in highly turbulent gas-rich disks. However, a clump formation event has not yet been observed, and it is debated whether clumps can survive energetic feedback from young stars, and afterwards migrate inwards to form galaxy bulges. Here we report the spatially resolved spectroscopy of a bright off-nuclear emission line region in a galaxy at z = 1.987. Although this region dominates star formation in the galaxy disk, its stellar continuum remains undetected in deep imaging, revealing an extremely young (less than ten million years old) massive clump, forming through the gravitational collapse of more than one billion solar masses of gas. Gas consumption in this young clump is more than tenfold faster than in the host galaxy, displaying high star-formation efficiency during this phase, in agreement with our hydrodynamic simulations. The frequency of older clumps with similar masses, coupled with our initial estimate of their formation rate (about 2.5 per billion years), supports long lifetimes (about 500 million years), favouring models in which clumps survive feedback and grow the bulges of present-day galaxies.

  2. Stellar kinematics of X-ray bright massive elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Lyskova, N.; Churazov, E.; Moiseev, A.; Sil'chenko, O.; Zhuravleva, I.

    2014-07-01

    We discuss a simple and fast method for estimating masses of early-type galaxies from optical data and compare the results with X-ray derived masses. The optical method relies only on the most basic observables such as the surface brightness I(R) and the line-of-sight velocity dispersion σp(R) profiles and provides an anisotropy-independent estimate of the galaxy circular speed Vc. The mass-anisotropy degeneracy is effectively overcome by evaluating Vc at a characteristic radius Rsweet defined from local properties of observed profiles. The sweet radius Rsweet is expected to lie close to R2, where I(R) ∝ R-2, and not far from the effective radius Reff. We apply the method to a sample of five X-ray bright elliptical galaxies observed with the 6 m telescope BTA-6 in Russia. We then compare the optical Vc estimate with the X-ray derived value, and discuss possible constraints on the non-thermal pressure in the hot gas and configuration of stellar orbits. We find that the average ratio of the optical Vc estimate to the X-ray one is equal to ≈0.98 with 11 per cent scatter, i.e. there is no evidence for the large non-thermal pressure contribution in the gas at ˜Rsweet. From analysis of the Lick indices Hβ, Mgb, Fe5270 and Fe5335, we calculate the mass of the stellar component within the sweet radius. We conclude that a typical dark matter fraction inside Rsweet in the sample galaxies is ˜60 per cent for the Salpeter initial mass function (IMF) and ˜75 per cent for the Kroupa IMF.

  3. Rapid growth of black holes in massive star-forming galaxies.

    PubMed

    Alexander, D M; Smail, I; Bauer, F E; Chapman, S C; Blain, A W; Brandt, W N; Ivison, R J

    2005-04-07

    The tight relationship between the masses of black holes and galaxy spheroids in nearby galaxies implies a causal connection between the growth of these two components. Optically luminous quasars host the most prodigious accreting black holes in the Universe, and can account for greater than or approximately equal to 30 per cent of the total cosmological black-hole growth. As typical quasars are not, however, undergoing intense star formation and already host massive black holes (> 10(8)M(o), where M(o) is the solar mass), there must have been an earlier pre-quasar phase when these black holes grew (mass range approximately (10(6)-10(8))M(o)). The likely signature of this earlier stage is simultaneous black-hole growth and star formation in distant (redshift z > 1; >8 billion light years away) luminous galaxies. Here we report ultra-deep X-ray observations of distant star-forming galaxies that are bright at submillimetre wavelengths. We find that the black holes in these galaxies are growing almost continuously throughout periods of intense star formation. This activity appears to be more tightly associated with these galaxies than any other coeval galaxy populations. We show that the black-hole growth from these galaxies is consistent with that expected for the pre-quasar phase.

  4. The Stellar Populations in the Outer Banks of Massive Disk Galaxies

    NASA Astrophysics Data System (ADS)

    De Jong, Roelof; GHOSTS Team

    2006-12-01

    In recent years we have started to appreciate that the outer banks of galaxies contain valuable information about the formation process of galaxies. In hierarchical galaxy formation the stellar halos and thick disks of galaxies are formed by accretion of minor satellites, predominantly in the earlier assembly phases. The size, metallicity, and amount of substructure in current day halos are therefore directly related to issues like the small scale properties of the primordial power spectrum of density fluctuations and the suppression of star formation in small dark matter halos after reionization. We will show initial results from our ongoing HST/ACS GHOSTS (Galaxy Halos, Outer disks, Star clusters, Thick disks, and Substructure) survey of the resolved stellar populations of 14 nearby, massive disk galaxies. We will show that the smaller galaxies have no significant halo. We will present the stellar populations of a very low surface brightness stream around M83, the first such a stream resolved into stars beyond those of the Milky Way and M31. Finally, we will show that the old RGB stars of the thick disk in an edge-on galaxy truncate at the same radius as the young thin disk stars, providing insights into the formation of both disk truncations and thick disks.

  5. The Coevolution of Nuclear Star Clusters, Massive Black Holes, and Their Host Galaxies

    NASA Astrophysics Data System (ADS)

    Antonini, Fabio; Barausse, Enrico; Silk, Joseph

    2015-10-01

    Studying how nuclear star clusters (NSCs) form and how they are related to the growth of the central massive black holes (MBHs) and their host galaxies is fundamental for our understanding of the evolution of galaxies and the processes that have shaped their central structures. We present the results of a semi-analytical galaxy formation model that follows the evolution of dark matter halos along merger trees, as well as that of the baryonic components. This model allows us to study the evolution of NSCs in a cosmological context, by taking into account the growth of NSCs due to both dynamical-friction-driven migration of stellar clusters and star formation triggered by infalling gas, while also accounting for dynamical heating from (binary) MBHs. We find that in situ star formation contributes a significant fraction (up to ∼80%) of the total mass of NSCs in our model. Both NSC growth through in situ star formation and that through star cluster migration are found to generate NSC—host galaxy scaling correlations that are shallower than the same correlations for MBHs. We explore the role of galaxy mergers on the evolution of NSCs and show that observational data on NSC—host galaxy scaling relations provide evidence of partial erosion of NSCs by MBH binaries in luminous galaxies. We show that this observational feature is reproduced by our models, and we make predictions about the NSC and MBH occupation fraction in galaxies. We conclude by discussing several implications for theories of NSC formation.

  6. Strong Lens Models for Massive Galaxy Clusters in the Reionization Lensing Cluster Survey

    NASA Astrophysics Data System (ADS)

    Cerny, Catherine; Sharon, Keren; Coe, Dan A.; Paterno-Mahler, Rachel; Jones, Christine; Czakon, Nicole G.; Umetsu, Keiichi; Stark, Daniel; Bradley, Larry D.; Trenti, Michele; Johnson, Traci; Bradac, Marusa; Dawson, William; Rodney, Steven A.; Strolger, Louis-Gregory; RELICS Team

    2017-01-01

    We present strong lensing models for five galaxy clusters from the Planck SZ cluster catalog as a part of the Reionization Lensing Cluster Survey (RELICS), a program that seeks to constrain the galaxy luminosity function past z~9 by conducting a wide field survey of massive galaxy clusters with HST (GO-14096, PI: Coe). The strong gravitational lensing effects of these clusters significantly magnify background galaxies, which enhances our ability to discover the large numbers of high redshift galaxies at z~9-12 needed to create a representative sample. We use strong lensing models for these clusters to study their mass distribution and magnification, which allows us to quantify the lensing effect on the background galaxies. These models can then be utilized in the RELICS survey in order to identify high redshift galaxy candidates that may be lensed by the clusters. The intrinsic properties of these galaxy candidates can be derived by removing the lensing effect as predicted by our models, which will meet the science goals of the RELICS survey. We use HST WFC3 and ACS imaging to create lensing models for the clusters RXC J0142.9+4438, ACO-2537, ACO-2163, RXCJ2211.7-0349, and ACT-CLJ0102-49151.

  7. Giant clumps in the FIRE simulations: a case study of a massive high-redshift galaxy

    NASA Astrophysics Data System (ADS)

    Oklopčić, Antonija; Hopkins, Philip F.; Feldmann, Robert; Kereš, Dušan; Faucher-Giguère, Claude-André; Murray, Norman

    2017-02-01

    The morphology of massive star-forming galaxies at high redshift is often dominated by giant clumps of mass ˜108-109 M⊙ and size ˜100-1000 pc. Previous studies have proposed that giant clumps might have an important role in the evolution of their host galaxy, particularly in building the central bulge. However, this depends on whether clumps live long enough to migrate from their original location in the disc or whether they get disrupted by their own stellar feedback before reaching the centre of the galaxy. We use cosmological hydrodynamical simulations from the FIRE (Feedback in Realistic Environments) project which implement explicit treatments of stellar feedback and interstellar medium physics to study the properties of these clumps. We follow the evolution of giant clumps in a massive (M* ˜ 1010.8 M⊙ at z = 1), discy, gas-rich galaxy from redshift z ≳ 2 to z = 1. Even though the clumpy phase of this galaxy lasts over a gigayear, individual gas clumps are short-lived, with mean lifetime of massive clumps of ˜20 Myr. During that time, they turn between 0.1 per cent and 20 per cent of their gas into stars before being disrupted, similar to local giant molecular clouds. Clumps with M ≳ 107 M⊙ account for ˜20 per cent of the total star formation in the galaxy during the clumpy phase, producing ˜1010 M⊙ of stars. We do not find evidence for net inward migration of clumps within the galaxy. The number of giant clumps and their mass decrease at lower redshifts, following the decrease in the overall gas fraction and star formation rate.

  8. Constraining Metallicity and Age for Massive Quiescent Galaxies in a Redshift Range of 1

    NASA Astrophysics Data System (ADS)

    Estrada-Carpenter, Vicente; Papovich, Casey J.; Momcheva, Ivelina G.; Brammer, Gabriel; Bridge, Joanna; Dickinson, Mark; Closson Ferguson, Henry; finlator, kristian; Finkelstein, Steven L.; Giavalisco, Mauro; Gosmeyer, Catherine; Livermore, Rachael C.; Long, James; Lotz, Jennifer M.; Kawinwanichakij, Lalitwadee; Pirzkal, Norbert; Quadri, Ryan; Salmon, Brett W.; Tilvi, Vithal; Trump, Jonathan R.; Weiner, Benjamin J.

    2017-01-01

    Using HST/WFC3 grism spectroscopy from the CANDELS Lyman-alpha Emission at Reionization (CLEAR) survey, we constrain the metallicities and ages of massive quiescent galaxies, at z ~ 1.5. CLEAR provides deep spectroscopy (12 HST orbits per pointing) with the WFC3/G102 grism over the wavelength range ~ 7,500 < λ < 12,000 Å, at a spectral resolution of R ~ 200, within the GOODS-N and GOODS-S Deep regions of CANDELS. These data cover important age and metallicity sensitive spectral features for galaxies at 1 < z < 2, including the redshifted Ca HK lines, 4000 Å break, Balmer-series lines, and Hg+G features. We stack the G102 spectra of a stellar-mass limited sample of 34 quiescent galaxies, with log(M*/M⊙) > 10 and 1 < z < 2, and fit the spectra using two sets of stellar population synthesis models, BC03 (Bruzual & Charlot 2003) and FSPS (Flexible Stellar Population Synthesis, Conroy & Gunn 2010). From these fits, we construct probability distribution functions of age and metallicity for these galaxies, separated into two mass bins, 10 < log(M*/M⊙) < 10.9 and log(M*/M⊙) > 10.9. The model fits favor higher metallicity for the more massive quiescent galaxies, with Z/Z⊙ ~ 1, with some systematics possibly leading from differences in the stellar population models. Therefore, there is no evidence for significant evolution in metallicity for the most massive quiescent galaxies since z ~ 1.5. The model fits to the lower mass quiescent galaxies favor lower metallicites, Z/Z⊙ ~ 0.4, with an offset of ~ 0.3 dex from the present-day relation (e.g., Galazzi et al. 2005). For quiescent galaxies in this mass range, 10.0 < log(M*/M⊙) < 10.9, this requires evolution in metallicity, either as a result of continued chemical enrichment of current galaxies, or the formation of additional quiescent galaxies (presumably quenching of star-forming galaxies at z > 1), or a combination of the two.

  9. SHAPE EVOLUTION OF MASSIVE EARLY-TYPE GALAXIES: CONFIRMATION OF INCREASED DISK PREVALENCE AT z > 1

    SciTech Connect

    Chang, Yu-Yen; Van der Wel, Arjen; Rix, Hans-Walter; Ramkumar, Balasubramanian; Wuyts, Stijn; Zibetti, Stefano; Holden, Bradford

    2013-01-10

    We use high-resolution K-band VLT/HAWK-I imaging over 0.25 deg{sup 2} to study the structural evolution of massive early-type galaxies since z {approx} 2. Mass-selected samples, complete down to log(M/M {sub Sun }) {approx} 10.7 such that 'typical' (L*) galaxies are included at all redshifts, are drawn from pre-existing photometric redshift surveys. We then separate the samples into different redshift slices and classify them as late- or early-type galaxies on the basis of their specific star formation rate. Axis-ratio measurements for the {approx}400 early-type galaxies in the redshift range 0.6 < z < 1.8 are accurate to 0.1 or better. The projected axis-ratio distributions are then compared with lower redshift samples. We find strong evidence for evolution of the population properties: early-type galaxies at z > 1 are, on average, flatter than at z < 1 and the median projected axis ratio at a fixed mass decreases with redshift. However, we also find that at all epochs z {approx}< 2, the most massive early-type galaxies (log(M/M {sub Sun }) > 11.3) are the roundest, with a pronounced lack of galaxies that are flat in projection. Merging is a plausible mechanism that can explain both results: at all epochs, merging is required for early-type galaxies to grow beyond log(M/M {sub Sun }) {approx} 11.3, and all early types over time gradually and partially lose their disk-like characteristics.

  10. Shape Evolution of Massive Early-type Galaxies: Confirmation of Increased Disk Prevalence at z > 1

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Yen; van der Wel, Arjen; Rix, Hans-Walter; Wuyts, Stijn; Zibetti, Stefano; Ramkumar, Balasubramanian; Holden, Bradford

    2013-01-01

    We use high-resolution K-band VLT/HAWK-I imaging over 0.25 deg2 to study the structural evolution of massive early-type galaxies since z ~ 2. Mass-selected samples, complete down to log(M/M ⊙) ~ 10.7 such that "typical" (L*) galaxies are included at all redshifts, are drawn from pre-existing photometric redshift surveys. We then separate the samples into different redshift slices and classify them as late- or early-type galaxies on the basis of their specific star formation rate. Axis-ratio measurements for the ~400 early-type galaxies in the redshift range 0.6 < z < 1.8 are accurate to 0.1 or better. The projected axis-ratio distributions are then compared with lower redshift samples. We find strong evidence for evolution of the population properties: early-type galaxies at z > 1 are, on average, flatter than at z < 1 and the median projected axis ratio at a fixed mass decreases with redshift. However, we also find that at all epochs z <~ 2, the most massive early-type galaxies (log(M/M ⊙) > 11.3) are the roundest, with a pronounced lack of galaxies that are flat in projection. Merging is a plausible mechanism that can explain both results: at all epochs, merging is required for early-type galaxies to grow beyond log(M/M ⊙) ~ 11.3, and all early types over time gradually and partially lose their disk-like characteristics.

  11. The progenitors of the most massive galaxy clusters at 1 < z < 3

    NASA Astrophysics Data System (ADS)

    Hatch, Nina; Brodwin, Mark; Cooke, Elizabeth; Galametz, Audrey; Gonzalez, Anthony; Muldrew, Stuart; Noirot, Gael; Smith, Daniel; Stern, Daniel; Vernet, Joel; Wylezalek, Dominika

    2016-08-01

    This project will locate and characterize the progenitors of the most massive galaxy clusters in our Universe at z ~ 2. These rare, massive objects are cosmological probes that test the validity of Lambda-CDM, and open a window into the early formation of the oldest and most massive galaxies in the most extreme overdensities in the Universe. Searching across 10,000 square degrees of the SDSS BOSS survey we have located 27 spectroscopically confirmed groups of radio-loud quasars at 1.3 < z < 3.2. Radio-loud quasars are preferentially located in high-redshift clusters and protoclusters (Wylezalek et al. 2013; Hatch et al. 2014), but the association of several radio-loud quasars implies the presence of an agglomeration of several >10^13 solar mass dark matter haloes that will eventually combine to form some of the most massive clusters in the Universe (Orsi et al. 2016; see Fig. 1). In this proposal we request 119.1 hours to observe all 27 radio-loud quasar groups in order to identify the associated galaxy overdensities that makes up the collapsing clusters.

  12. A massive galaxy in its core formation phase three billion years after the Big Bang.

    PubMed

    Nelson, Erica; van Dokkum, Pieter; Franx, Marijn; Brammer, Gabriel; Momcheva, Ivelina; Schreiber, Natascha Förster; da Cunha, Elisabete; Tacconi, Linda; Bezanson, Rachel; Kirkpatrick, Allison; Leja, Joel; Rix, Hans-Walter; Skelton, Rosalind; van der Wel, Arjen; Whitaker, Katherine; Wuyts, Stijn

    2014-09-18

    Most massive galaxies are thought to have formed their dense stellar cores in early cosmic epochs. Previous studies have found galaxies with high gas velocity dispersions or small apparent sizes, but so far no objects have been identified with both the stellar structure and the gas dynamics of a forming core. Here we report a candidate core in the process of formation 11 billion years ago, at redshift z = 2.3. This galaxy, GOODS-N-774, has a stellar mass of 100 billion solar masses, a half-light radius of 1.0 kiloparsecs and a star formation rate of solar masses per year. The star-forming gas has a velocity dispersion of 317 ± 30 kilometres per second. This is similar to the stellar velocity dispersions of the putative descendants of GOODS-N-774, which are compact quiescent galaxies at z ≈ 2 (refs 8-11) and giant elliptical galaxies in the nearby Universe. Galaxies such as GOODS-N-774 seem to be rare; however, from the star formation rate and size of this galaxy we infer that many star-forming cores may be heavily obscured, and could be missed in optical and near-infrared surveys.

  13. The Hierarchical Build-Up of Massive Galaxies And the Intracluster Light Since z=1

    SciTech Connect

    Conroy, Charlie; Wechsler, Risa H.; Kravtsov, Andrey V.; /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI

    2007-03-19

    We use a set of simulation-based models for the dissipationless evolution of galaxies since z = 1 to constrain the fate of accreted satellites embedded in dark matter subhalos. These models assign stellar mass to dark matter halos at z = 1 by relating the observed galaxy stellar mass function (GSMF) to the halo+subhalo mass function monotonically. The evolution of the stellar mass content is then followed using halo merger trees extracted from N-body simulations. Our models are differentiated only in the fate assigned to satellite galaxies once subhalos, within which satellites are embedded, disrupt. These models are confronted with the observed evolution in the massive end of the GSMF, the z {approx} 0 brightest cluster galaxy (BCG)-cluster mass relation, and the combined BCG and intracluster light (ICL) luminosity distribution--all observables expected to evolve approximately dissipationlessly since z = 1. The combined observational constraints favor a model in which the vast majority ({approx}> 80%) of satellite stars from disrupted subhalos go into the ICL (operationally defined here as light below a surface brightness cut of {mu}{sub i} {approx} 23mag arcsec{sup -2}). Conversely, models that leave behind a significant population of satellite galaxies once the subhalo has disrupted are strongly disfavored, as are models that put a significant fraction of satellite stars into the BCG. Our results show that observations of the ICL provide useful and unique constraints on models of galaxy merging and the dissipationless evolution of galaxies in groups and clusters.

  14. The stellar accretion origin of stellar population gradients in massive galaxies at large radii

    NASA Astrophysics Data System (ADS)

    Hirschmann, Michaela; Naab, Thorsten; Ostriker, Jeremiah P.; Forbes, Duncan A.; Duc, Pierre-Alain; Davé, Romeel; Oser, Ludwig; Karabal, Emin

    2015-05-01

    We investigate the evolution of stellar population gradients from z = 2 to 0 in massive galaxies at large radii (r > 2Reff) using 10 cosmological zoom simulations of haloes with 6 × 1012 M⊙ < Mhalo < 2 × 1013 M⊙. The simulations follow metal cooling and enrichment from SNII, SNIa and asymptotic giant branch winds. We explore the differential impact of an empirical model for galactic winds that reproduces the mass-metallicity relation and its evolution with redshift. At larger radii the galaxies, for both models, become more dominated by stars accreted from satellite galaxies in major and minor mergers. In the wind model, fewer stars are accreted, but they are significantly more metal-poor resulting in steep global metallicity (<∇Zstars> = -0.35 dex dex-1) and colour (e.g. <∇g - r> = -0.13 dex dex-1) gradients in agreement with observations. In contrast, colour and metallicity gradients of the models without winds are inconsistent with observations. Age gradients are in general mildly positive at z = 0 (<∇Agestars> = 0.04 dex dex-1) with significant differences between the models at higher redshift. We demonstrate that for the wind model, stellar accretion is steepening existing in situ metallicity gradients by about 0.2 dex by the present day and helps to match observed gradients of massive early-type galaxies at large radii. Colour and metallicity gradients are significantly steeper for systems which have accreted stars in minor mergers, while galaxies with major mergers have relatively flat gradients, confirming previous results. The effect of stellar migration of in situ formed stars to large radii is discussed. This study highlights the importance of stellar accretion for stellar population properties of massive galaxies at large radii, which can provide important constraints for formation models.

  15. Photometric Selection of a Massive Galaxy Catalog with z ≥ 0.55

    NASA Astrophysics Data System (ADS)

    Núñez, Carolina; Spergel, David N.; Ho, Shirley

    2017-02-01

    We present the development of a photometrically selected massive galaxy catalog, targeting Luminous Red Galaxies (LRGs) and massive blue galaxies at redshifts of z≥slant 0.55. Massive galaxy candidates are selected using infrared/optical color–color cuts, with optical data from the Sloan Digital Sky Survey (SDSS) and infrared data from “unWISE” forced photometry derived from the Wide-field Infrared Survey Explorer (WISE). The selection method is based on previously developed techniques to select LRGs with z> 0.5, and is optimized using receiver operating characteristic curves. The catalog contains 16,191,145 objects, selected over the full SDSS DR10 footprint. The redshift distribution of the resulting catalog is estimated using spectroscopic redshifts from the DEEP2 Galaxy Redshift Survey and photometric redshifts from COSMOS. Restframe U ‑ B colors from DEEP2 are used to estimate LRG selection efficiency. Using DEEP2, the resulting catalog has an average redshift of z = 0.65, with a standard deviation of σ =2.0, and an average restframe of U-B=1.0, with a standard deviation of σ =0.27. Using COSMOS, the resulting catalog has an average redshift of z = 0.60, with a standard deviation of σ =1.8. We estimate 34 % of the catalog to be blue galaxies with z≥slant 0.55. An estimated 9.6 % of selected objects are blue sources with redshift z< 0.55. Stellar contamination is estimated to be 1.8%.

  16. A WISE Search for the Most Massive High-Redshift Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Gonzalez, Anthony

    We propose a comprehensive program to detect and characterize the most massive galaxy clusters at z>1 over half the sky. The foundation for this program is the Preliminary Release data from the NASA Wide-field Infrared Survey Explorer (WISE). WISE is an all-sky infrared survey mission for which the first 23,600 sq. deg. of data are publicly available, providing images and photometric catalogs at 3.4, 4.6, 12, and 22 microns. The shortest wavelength band achieves a 5-sigma depth of 50 microJansky, which is sufficient to detect L* galaxies out to a z~1 (8 Gyr lookback time). Our team has developed a modified version of a cluster detection algorithm developed by Papovich (2008) that employs color selection in the two bluest bands (3.4 and 4.6 microns) to isolate galaxies at z>1 and identify galaxy clusters as overdensities of galaxies brighter than L*. The technique has been been tested using WISE data for a small (3,000 sq. deg.) subfield and optimized to enable an efficient search over the full Preliminary Release area. Within this subfield we find candidates that appear comparable to the most massive z>1 systems known. As a continuation of this pilot study, we propose to conduct a search over the full PR area (excluding the galactic plane) for high-redshift clusters. We will use multiwavelength observations of known and newly confirmed clusters to understand the mass and redshift selection function. The cluster sample resulting from this program is designed to be optimal for investigations of the Gaussianity of the initial density perturbations after inflation, the evolution of massive galaxies in the most overdense environments during their epoch of star formation and mass assembly, and the high-redshift Universe by employing the clusters as gravitational telescopes.

  17. Which processes shape stellar population gradients of massive galaxies at large radii?

    NASA Astrophysics Data System (ADS)

    Hirschmann, Michaela

    2016-08-01

    We investigate the differential impact of physical mechanisms, mergers (stellar accretion) and internal energetic phenomena, on the evolution of stellar population gradients in massive, present-day galaxies employing a set of high-resolution, cosmological zoom simulations. We demonstrate that negative metallicity and color gradients at large radii (>2Reff) originate from the accretion of metal-poor stellar systems. At larger radii, galaxies become typically more dominated by stars accreted from satellite galaxies in major and minor mergers. However, only strong galactic winds can sufficiently reduce the metallicity content of the accreted stars to realistically steepen the outer metallicity and colour gradients in agreement with present-day observations. In contrast, the gradients of the models without winds are inconsistent with observations (too flat). In the wind model, colour and metallicity gradients are significantly steeper for systems which have accreted stars in minor mergers, while galaxies with major mergers have relatively flat gradients, confirming previous results. This analysis greatly highlights the importance of both energetic processes and merger events for stellar population properties of massive galaxies at large radii. Our results are expected to significantly contribute to the interpretation of current and up-coming IFU surveys (like MaNGA and Califa), which in turn can help to better constrain still uncertain models for energetic processes in simulations.

  18. A Substantial Population of Massive Quiescent Galaxies at z ~ 4 from ZFOURGE

    NASA Astrophysics Data System (ADS)

    Straatman, Caroline M. S.; Labbé, Ivo; Spitler, Lee R.; Allen, Rebecca; Altieri, Bruno; Brammer, Gabriel B.; Dickinson, Mark; van Dokkum, Pieter; Inami, Hanae; Glazebrook, Karl; Kacprzak, Glenn G.; Kawinwanichakij, Lalit; Kelson, Daniel D.; McCarthy, Patrick J.; Mehrtens, Nicola; Monson, Andy; Murphy, David; Papovich, Casey; Persson, S. Eric; Quadri, Ryan; Rees, Glen; Tomczak, Adam; Tran, Kim-Vy H.; Tilvi, Vithal

    2014-03-01

    We report the likely identification of a substantial population of massive M ~ 1011 M ⊙ galaxies at z ~ 4 with suppressed star formation rates (SFRs), selected on rest-frame optical to near-IR colors from the FourStar Galaxy Evolution Survey (ZFOURGE). The observed spectral energy distributions show pronounced breaks, sampled by a set of near-IR medium-bandwidth filters, resulting in tightly constrained photometric redshifts. Fitting stellar population models suggests large Balmer/4000 Å breaks, relatively old stellar populations, large stellar masses, and low SFRs, with a median specific SFR of 2.9 ± 1.8 × 10-11 yr-1. Ultradeep Herschel/PACS 100 μm, 160 μm and Spitzer/MIPS 24 μm data reveal no dust-obscured SFR activity for 15/19(79%) galaxies. Two far-IR detected galaxies are obscured QSOs. Stacking the far-IR undetected galaxies yields no detection, consistent with the spectral energy distribution fit, indicating independently that the average specific SFR is at least 10 × smaller than that of typical star-forming galaxies at z ~ 4. Assuming all far-IR undetected galaxies are indeed quiescent, the volume density is 1.8 ± 0.7 × 10-5 Mpc-3 to a limit of log10 M/M ⊙ >= 10.6, which is 10 × and 80 × lower than at z = 2 and z = 0.1. They comprise a remarkably high fraction (~35%) of z ~ 4 massive galaxies, suggesting that suppression of star formation was efficient even at very high redshift. Given the average stellar age of 0.8 Gyr and stellar mass of 0.8 × 1011 M ⊙, the galaxies likely started forming stars before z = 5, with SFRs well in excess of 100 M ⊙ yr-1, far exceeding that of similarly abundant UV-bright galaxies at z >= 4. This suggests that most of the star formation in the progenitors of quiescent z ~ 4 galaxies was obscured by dust. This Letter contains data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  19. A SUBSTANTIAL POPULATION OF MASSIVE QUIESCENT GALAXIES AT z ∼ 4 FROM ZFOURGE

    SciTech Connect

    Straatman, Caroline M. S.; Labbé, Ivo; Spitler, Lee R.; Allen, Rebecca; Glazebrook, Karl; Kacprzak, Glenn G.; Altieri, Bruno; Dickinson, Mark; Inami, Hanae; Van Dokkum, Pieter; Kawinwanichakij, Lalit; Mehrtens, Nicola; Papovich, Casey; Kelson, Daniel D.; McCarthy, Patrick J.; Monson, Andy; Murphy, David; Persson, S. Eric; Quadri, Ryan; and others

    2014-03-01

    We report the likely identification of a substantial population of massive M ∼ 10{sup 11} M {sub ☉} galaxies at z ∼ 4 with suppressed star formation rates (SFRs), selected on rest-frame optical to near-IR colors from the FourStar Galaxy Evolution Survey (ZFOURGE). The observed spectral energy distributions show pronounced breaks, sampled by a set of near-IR medium-bandwidth filters, resulting in tightly constrained photometric redshifts. Fitting stellar population models suggests large Balmer/4000 Å breaks, relatively old stellar populations, large stellar masses, and low SFRs, with a median specific SFR of 2.9 ± 1.8 × 10{sup –11} yr{sup –1}. Ultradeep Herschel/PACS 100 μm, 160 μm and Spitzer/MIPS 24 μm data reveal no dust-obscured SFR activity for 15/19(79%) galaxies. Two far-IR detected galaxies are obscured QSOs. Stacking the far-IR undetected galaxies yields no detection, consistent with the spectral energy distribution fit, indicating independently that the average specific SFR is at least 10 × smaller than that of typical star-forming galaxies at z ∼ 4. Assuming all far-IR undetected galaxies are indeed quiescent, the volume density is 1.8 ± 0.7 × 10{sup –5} Mpc{sup –3} to a limit of log{sub 10} M/M {sub ☉} ≥ 10.6, which is 10 × and 80 × lower than at z = 2 and z = 0.1. They comprise a remarkably high fraction (∼35%) of z ∼ 4 massive galaxies, suggesting that suppression of star formation was efficient even at very high redshift. Given the average stellar age of 0.8 Gyr and stellar mass of 0.8 × 10{sup 11} M {sub ☉}, the galaxies likely started forming stars before z = 5, with SFRs well in excess of 100 M {sub ☉} yr{sup –1}, far exceeding that of similarly abundant UV-bright galaxies at z ≥ 4. This suggests that most of the star formation in the progenitors of quiescent z ∼ 4 galaxies was obscured by dust.

  20. EVIDENCE FOR WIDESPREAD ACTIVE GALACTIC NUCLEUS ACTIVITY AMONG MASSIVE QUIESCENT GALAXIES AT z {approx} 2

    SciTech Connect

    Olsen, Karen P.; Rasmussen, Jesper; Toft, Sune; Zirm, Andrew W.

    2013-02-10

    We quantify the presence of active galactic nuclei (AGNs) in a mass-complete (M {sub *} > 5 Multiplication-Sign 10{sup 10} M {sub Sun }) sample of 123 star-forming and quiescent galaxies at 1.5 {<=} z {<=} 2.5, using X-ray data from the 4 Ms Chandra Deep Field-South (CDF-S) survey. 41% {+-} 7% of the galaxies are detected directly in X-rays, 22% {+-} 5% with rest-frame 0.5-8 keV luminosities consistent with hosting luminous AGNs (L {sub 0.5-8keV} > 3 Multiplication-Sign 10{sup 42} erg s{sup -1}). The latter fraction is similar for star-forming and quiescent galaxies, and does not depend on galaxy stellar mass, suggesting that perhaps luminous AGNs are triggered by external effects such as mergers. We detect significant mean X-ray signals in stacked images for both the individually non-detected star-forming and quiescent galaxies, with spectra consistent with star formation only and/or a low-luminosity AGN in both cases. Comparing star formation rates inferred from the 2-10 keV luminosities to those from rest-frame IR+UV emission, we find evidence for an X-ray excess indicative of low-luminosity AGNs. Among the quiescent galaxies, the excess suggests that as many as 70%-100% of these contain low- or high-luminosity AGNs, while the corresponding fraction is lower among star-forming galaxies (43%-65%). Our discovery of the ubiquity of AGNs in massive, quiescent z {approx} 2 galaxies provides observational support for the importance of AGNs in impeding star formation during galaxy evolution.

  1. The MASSIVE survey. I. A volume-limited integral-field spectroscopic study of the most massive early-type galaxies within 108 Mpc

    SciTech Connect

    Ma, Chung-Pei; Greene, Jenny E.; Murphy, Jeremy D.; McConnell, Nicholas; Janish, Ryan; Blakeslee, John P.; Thomas, Jens

    2014-11-10

    Massive early-type galaxies represent the modern day remnants of the earliest major star formation episodes in the history of the universe. These galaxies are central to our understanding of the evolution of cosmic structure, stellar populations, and supermassive black holes, but the details of their complex formation histories remain uncertain. To address this situation, we have initiated the MASSIVE Survey, a volume-limited, multi-wavelength, integral-field spectroscopic (IFS) and photometric survey of the structure and dynamics of the ∼100 most massive early-type galaxies within a distance of 108 Mpc. This survey probes a stellar mass range M* ≳ 10{sup 11.5} M {sub ☉} and diverse galaxy environments that have not been systematically studied to date. Our wide-field IFS data cover about two effective radii of individual galaxies, and for a subset of them, we are acquiring additional IFS observations on sub-arcsecond scales with adaptive optics. We are also acquiring deep K-band imaging to trace the extended halos of the galaxies and measure accurate total magnitudes. Dynamical orbit modeling of the combined data will allow us to simultaneously determine the stellar, black hole, and dark matter halo masses. The primary goals of the project are to constrain the black hole scaling relations at high masses, investigate systematically the stellar initial mass function and dark matter distribution in massive galaxies, and probe the late-time assembly of ellipticals through stellar population and kinematical gradients. In this paper, we describe the MASSIVE sample selection, discuss the distinct demographics and structural and environmental properties of the selected galaxies, and provide an overview of our basic observational program, science goals and early survey results.

  2. Examining the Center: Positions, Dominance, and Star Formation Rates of Most Massive Group Galaxies at Intermediate Redshift

    NASA Astrophysics Data System (ADS)

    Connelly, Jennifer L.; Parker, Laura C.; McGee, Sean; Mulchaey, John S.; Finoguenov, Alexis; Balogh, Michael; Wilman, David; Group Environment Evolution Collaboration

    2015-01-01

    The group environment is believed to be the stage for many galaxy transformations, helping evolve blue star-forming galaxies to red passive ones. In local studies of galaxy clusters, the central member is usually a single dominant giant galaxy at the center of the potential with little star formation thought to be the result of galaxy mergers. In nearby groups, a range of morphologies and star formation rates are observed and the formation history is less clear. Further, the position and dominance of the central galaxy cannot be assumed in groups, which are less massive and evolved than clusters. To understand the connections between global group properties and properties of the central group galaxy at intermediate redshift, we examine galaxy groups from the Group Environment and Evolution Collaboration (GEEC) catalog, including both optically- and X-ray-selected groups at redshift z~0.4. The sample is diverse, containing a range in overall mass and evolutionary state. The number of groups is significant, membership is notably complete, and measurements span the IR to the UV allowing the properties of the members to be connected to those of the host groups. Having investigated trends in the global group properties previously, including mass and velocity substructure, we turn our attention now to the galaxy populations, focusing on the central regions of these systems. The most massive and second most massive group galaxies are identified by their stellar mass. The positions of the most massive galaxies (MMGs) are determined with respect to both the luminosity-weighted and X-ray center. Star formation rates are used to explore the fraction of passive/quiescent versus star-forming MMGs and the dominance of the MMGs in our group sample is also tested. Determinations of these characteristics and trends constitute the important first steps toward a detailed understanding of the relationships between the properties of host groups and their most massive galaxies and the

  3. Gravitational waves and stalled satellites from massive galaxy mergers at z ≤ 1

    SciTech Connect

    McWilliams, Sean T.; Pretorius, Frans; Ostriker, Jeremiah P.

    2014-07-10

    We present a model for merger-driven evolution of the mass function for massive galaxies and their central supermassive black holes at late times. We discuss the current observational evidence in favor of merger-driven massive galaxy evolution during this epoch, and demonstrate that the observed evolution of the mass function can be reproduced by evolving an initial mass function under the assumption of negligible star formation. We calculate the stochastic gravitational wave signal from the resulting black hole binary mergers in the low redshift universe (z ≤ 1) implied by this model, and find that this population has a signal-to-noise ratio 2 × to 5 × larger than previous estimates for pulsar timing arrays, with a (2σ, 3σ) lower limit within this model of h{sub c}(f = 1 yr{sup –1}) = (1.1 × 10{sup –15}, 6.8 × 10{sup –16}). The strength of this signal is sufficient to make it detectable with high probability under conservative assumptions within the next several years. A principle reason that this result is larger than previous estimates is our use of a recent recalibration of the black hole-stellar mass correlation for the brightest cluster galaxies, which increases our estimate by a factor of ∼2 relative to past results. For cases where a galaxy merger fails to lead to a black hole merger, we estimate the probability for a given number of satellite black holes to remain within a massive host galaxy, and interpret the result in light of ULX observations. We find that in rare cases, wandering supermassive black holes may be bright enough to appear as ULXs.

  4. A Massive Galaxy in Its Core Formation Phase Three Billion Years After the Big Bang

    NASA Technical Reports Server (NTRS)

    Nelson, Erica; van Dokkum, Pieter; Franx, Marijn; Brammer, Gabriel; Momcheva, Ivelina; Schreiber, Natascha M. Forster; da Cunha, Elisabete; Tacconi, Linda; Bezanson, Rachel; Kirkpatrick, Allison; Leja, Joel; Rix, Hans-Walter; Skelton, Rosalind; van der Wel, Arjen; Whitaker, Katherine; Wuyts, Stijn

    2014-01-01

    Most massive galaxies are thought to have formed their dense stellar cores at early cosmic epochs. However, cores in their formation phase have not yet been observed. Previous studies have found galaxies with high gas velocity dispersions or small apparent sizes but so far no objects have been identified with both the stellar structure and the gas dynamics of a forming core. Here we present a candidate core in formation 11 billion years ago, at z = 2.3. GOODS-N-774 has a stellar mass of 1.0 × 10 (exp 11) solar mass, a half-light radius of 1.0 kpc, and a star formation rate of 90 (sup +45 / sub -20) solar mass/yr. The star forming gas has a velocity dispersion 317 plus or minus 30 km/s, amongst the highest ever measured. It is similar to the stellar velocity dispersions of the putative descendants of GOODS-N-774, compact quiescent galaxies at z is approximately equal to 2 (exp 8-11) and giant elliptical galaxies in the nearby Universe. Galaxies such as GOODS-N-774 appear to be rare; however, from the star formation rate and size of the galaxy we infer that many star forming cores may be heavily obscured, and could be missed in optical and near-infrared surveys.

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

    NASA Technical Reports Server (NTRS)

    McDonald, M.; Bayliss, 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.; deHaan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Egami, E.; Joy, M.

    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(sub 2-10 keV) = 8.2 10(exp 45) erg/s) galaxy cluster which hosts an extremely strong cooling flow (M(sub cool) = 3820 +/- 530 Stellar Mass/yr). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (740 +/- 160 Stellar Mass/ yr), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form via accretion of the intracluster medium, rather than the current picture of central galaxies assembling entirely via mergers.

  6. STRONG GRAVITATIONAL LENSING BY THE SUPER-MASSIVE cD GALAXY IN ABELL 3827

    SciTech Connect

    Carrasco, E. R.; Gomez, P. L.; Lee, H.; Diaz, R.; Bergmann, M.; Turner, J. E. H.; Miller, B. W.; West, M. J.; Verdugo, T.

    2010-06-01

    We have discovered strong gravitational lensing features in the core of the nearby cluster Abell 3827 by analyzing Gemini South GMOS images. The most prominent strong lensing feature is a highly magnified, ring-shaped configuration of four images around the central cD galaxy. GMOS spectroscopic analysis puts this source at z {approx} 0.2. Located {approx}20'' away from the central galaxy is a secondary tangential arc feature which has been identified as a background galaxy with z {approx} 0.4. We have modeled the gravitational potential of the cluster core, taking into account the mass from the cluster, the brightest cluster galaxy (BCG), and other galaxies. We derive a total mass of (2.7 {+-} 0.4) x 10{sup 13} M {sub sun} within 37 h {sup -1} kpc. This mass is an order of magnitude larger than that derived from X-ray observations. The total mass derived from lensing data suggests that the BCG in this cluster is perhaps the most massive galaxy in the nearby universe.

  7. Mass assembly of galaxies from the MASSIV survey and the MIRAGE simulation sample

    NASA Astrophysics Data System (ADS)

    Amram, Philippe

    2015-08-01

    The MIRAGE (Merging & isolated high-redshift AMR galaxies, Perret et al. 2014) sample has been built in order to understand the contribution of the merger processes to the mass assembly in the MASSIV (Mass Assembly Survey with SINFONI in VVDS, Contini et al. 2012) sample. It consists of a sample of idealized simulations based on the RAMSES code; the initial conditions were designed to reproduce the physical properties of the most gas-rich young galaxies. It is composed of simulations of mergers exploring the initial parameters of mass and orientation of the disks with a spatial resolution reaching 7 parsecs. We carry out a comparative study of the MASSIV kinematical data to a set of more than 4000 pseudo-observations at z=1.7 built from simulations of the MIRAGE sample to determine the ability to detect galaxy merger signatures under the observational conditions of the SINFONI instrument. The MIRAGE simulations show (i) an absence of star formation bursts in mergers of fragmented and turbulent disks, suggesting a saturation mechanism; (ii) that the gas rich clump merging mechanism is able to control the bulge mass growth, to erode the central profile of the dark matter halo and to drive massive gas outflows into the disk plane; (iii) irrespectively of the orbital configuration and of the mass ratio between the disks a new disk of gas is reconstructed quickly after the merger.

  8. Mass Assembly of galaxies from the MASSIV survey and the MIRAGE simulation sample.

    NASA Astrophysics Data System (ADS)

    Amram, Philippe

    2015-08-01

    The MIRAGE (Merging & isolated high-redshift AMR galaxies, Perret et al. 2014) sample has been built in order to understand the contribution of the merger processes to the mass assembly in the MASSIV (Mass Assembly Survey with SINFONI in VVDS, Contini et al. 2012) sample. It consists of a sample of idealized simulations based on the RAMSES code; the initial conditions were designed to reproduce the physical properties of the most gas-rich young galaxies. It is composed of simulations of mergers exploring the initial parameters of mass and orientation of the disks with a spatial resolution reaching 7 parsecs. We carry out a comparative study of the MASSIV kinematical data to a set of more than 4000 pseudo-observations at z=1.7 built from simulations of the MIRAGE sample to determine the ability to detect galaxy merger signatures under the observational conditions of the SINFONI instrument. The MIRAGE simulations show (i) an absence of star formation bursts in mergers of fragmented and turbulent disks, suggesting a saturation mechanism; (ii) that the gas rich clump merging mechanism is able to control the bulge mass growth, to erode the central profile of the dark matter halo and to drive massive gas outflows into the disk plane; (iii) irrespectively of the orbital configuration and of the mass ratio between the disks a new disk of gas is reconstructed quickly after the merger.

  9. UV-selected Young Massive Star Cluster Populations in Nearby Star-forming Galaxies

    NASA Astrophysics Data System (ADS)

    Smith, Linda J.

    2015-08-01

    The Legacy ExtraGalactic UV Survey (LEGUS) is an HST Treasury program aimed at the investigation of star-formation and its relationship to environment in nearby galaxies. The results of a UV-selected study of young massive star clusters in a sample of nearby galaxies (< 10 Mpc) using detections based on the WFC3/UVIS F275W filter will be presented. Previous studies have used V or I-band detections and tend to ignore clusters younger than 10 Myr old. This very young population, which represents the most recent cluster-forming event in the LEGUS galaxies will be discussed.This poster is presented on behalf of the LEGUS team (PI Daniela Calzetti).

  10. Using deep images and simulations to trace collisional debris around massive galaxies

    NASA Astrophysics Data System (ADS)

    Duc, Pierre-Alain

    2017-03-01

    Deep imaging programs, such as MATLAS which has just been completed at the CFHT, allows us to study with their diffuse light the outer stellar populations around large number of galaxies. We have carried out a systematic census of their fine structures, i.e. the collisional debris from past mergers. We have identified among them stellar streams from minor mergers, tidal tails from gas-rich major mergers, plumes from gas-poor major mergers, and shells from intermediate mass mergers. Having estimated the visibility and life time of each of these structures with numerical simulations, we can reconstruct the past mass assembly of the host galaxy. Preliminary statistical results based on a sample of 360 massive nearby galaxies are presented.

  11. A Photometric and Spectroscopic Study of Massive and Evolved Galaxies at z > 3

    NASA Astrophysics Data System (ADS)

    Nayyeri, Hooshang

    I use deep data taken as part of the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) along with ground-based and Spitzer Space Telescope data to identify massive and evolved galaxies at z > 3. This is performed using the strength of the Balmer break feature at rest-frame 3648AA, which is an age dependent diagnostic of the stellar population, to develop a Balmer Break Galaxy (BBG) selection. Fitting the spectral energy distribution (SED) of the candidates show that these systems have average estimated ages of ~ 800 Myr and average stellar masses of ~ 5 x1010M_sun, consistent with being old and massive. I find a number density of ~ 3.2 x 10--5 Mpc--3 for these systems corresponding to a mass density of ~ 2.0 x 106 M_sun/Mpc3 at 3 < z < 3 are far more compact than lower redshift early type galaxies. Using the GALFIT measured sizes, I confirm that the physical size of the early type galaxies evolve rapidly with redshift according to: Re ∝ (1 + z) --1.48 out to z ~ 3.3.

  12. What shapes stellar metallicity gradients of massive galaxies at large radii?

    NASA Astrophysics Data System (ADS)

    Hirschmann, Michaela

    2017-03-01

    We investigate the differential impact of physical mechanisms, mergers and internal energetic phenomena, on the evolution of stellar metallicity gradients in massive, present-day galaxies employing sets of high-resolution, cosmological zoom simulations. We demonstrate that negative metallicity gradients at large radii (>2Reff) originate from the accretion of metal-poor stellar systems. At larger radii, galaxies become typically more dominated by stars accreted from satellite galaxies in major and minor mergers. However, only strong galactic, stellar-driven winds can sufficiently reduce the metallicity content of the accreted stars to realistically steepen the outer metallicity gradients in agreement with observations. In contrast, the gradients of the models without winds are inconsistent with observations. Moreover, we discuss the impact of additional AGN feedback. This analysis greatly highlights the importance of both energetic processes and merger events for stellar population properties of massive galaxies at large radii. Our results are expected to significantly contribute to the interpretation of current and up-coming IFU surveys (e.g. MaNGA, CALIFA).

  13. What are the Progenitors of Compace, Massive, Quiescent Galaxies at z (equals) 2.3? The Population of Massive Galaxies at z (greater than) 3 From NMBS AND CANDELS

    NASA Technical Reports Server (NTRS)

    Stefanon, Mauro; Marchesini, Danilo; Rudnick, Gregory H.; Brammer, Gabriel B.; Tease, Katherine Whitaker

    2013-01-01

    Using public data from the NEWFIRM Medium-Band Survey (NMBS) and the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS), we investigate the population of massive galaxies at z > 3. The main aim of this work is to identify the potential progenitors of z 2 compact, massive, quiescent galaxies (CMQGs), furthering our understanding of the onset and evolution of massive galaxies. Our work is enabled by high-resolution images from CANDELS data and accurate photometric redshifts, stellar masses, and star formation rates (SFRs) from 37-band NMBS photometry. The total number of massive galaxies at z > 3 is consistent with the number of massive, quiescent galaxies (MQGs) at z 2, implying that the SFRs for all of these galaxies must be much lower by z 2. We discover four CMQGs at z > 3, pushing back the time for which such galaxies have been observed. However, the volume density for these galaxies is significantly less than that of galaxies at z < 2 with similar masses, SFRs, and sizes, implying that additional CMQGs must be created in the intervening 1 Gyr between z = 3 and z = 2. We find five star-forming galaxies at z 3 that are compact (Re < 1.4 kpc) and have stellar mass M* > 1010.6M; these galaxies are likely to become members of the massive, quiescent, compact galaxy population at z 2. We evolve the stellar masses and SFRs of each individual z > 3 galaxy adopting five different star formation histories (SFHs) and studying the resulting population of massive galaxies at z = 2.3. We find that declining or truncated SFHs are necessary to match the observed number density of MQGs at z 2, whereas a constant delayed-exponential SFH would result in a number density significantly smaller than observed. All of our assumed SFHs imply number densities of CMQGs at z 2 that are consistent with the observed number density. Better agreement with the observed number density of CMQGs at z 2 is obtained if merging is included in the analysis and better still if

  14. Massive black hole and gas dynamics in galaxy nuclei mergers - I. Numerical implementation

    NASA Astrophysics Data System (ADS)

    Lupi, Alessandro; Haardt, Francesco; Dotti, Massimo

    2015-01-01

    Numerical effects are known to plague adaptive mesh refinement (AMR) codes when treating massive particles, e.g. representing massive black holes (MBHs). In an evolving background, they can experience strong, spurious perturbations and then follow unphysical orbits. We study by means of numerical simulations the dynamical evolution of a pair MBHs in the rapidly and violently evolving gaseous and stellar background that follows a galaxy major merger. We confirm that spurious numerical effects alter the MBH orbits in AMR simulations, and show that numerical issues are ultimately due to a drop in the spatial resolution during the simulation, drastically reducing the accuracy in the gravitational force computation. We therefore propose a new refinement criterion suited for massive particles, able to solve in a fast and precise way for their orbits in highly dynamical backgrounds. The new refinement criterion we designed enforces the region around each massive particle to remain at the maximum resolution allowed, independently upon the local gas density. Such maximally resolved regions then follow the MBHs along their orbits, and effectively avoids all spurious effects caused by resolution changes. Our suite of high-resolution, AMR hydrodynamic simulations, including different prescriptions for the sub-grid gas physics, shows that the new refinement implementation has the advantage of not altering the physical evolution of the MBHs, accounting for all the non-trivial physical processes taking place in violent dynamical scenarios, such as the final stages of a galaxy major merger.

  15. Is the Size Evolution of Massive Galaxies Accelerated in Cluster Environments?

    NASA Astrophysics Data System (ADS)

    Wilson, Gillian

    2013-10-01

    At z 1.6 the main progenitors of present-day massive clusters are undergoing rapid collapse, and have the highest rates of galaxy merging and assembly. Recent observational studies have hinted at accelerated galaxy evolution in dense environments at this epoch, including increased merger rates and rapid growth in galaxy size relative to the field. We propose WFC3 G102 spectroscopy and F125W {Broad J} imaging of a sample of four massive spectroscopically-confirmed clusters at z = 1.6. Our primary scientific goal is to leverage the CANDELS Wide Legacy dataset to carry out a head-to-head comparison of the sizes of cluster members relative to the field {as a function of stellar mass and Sersic index}, and quantify the role of environment in the observed rapid evolution in galaxy sizes since z = 2. These clusters are four of the highest significance overdensities in the 50 square degree SWIRE fields, and will evolve over time to have present-day masses similar to Coma. They were detected using IRAC [3.6]-[4.5] color, which identifies galaxy overdensities regardless of optically red or blue color. A heroic ground-based spectroscopic campaign has resulted in 44 spectroscopically-confirmed members. However this sample is heavily biased toward star-forming {SF} galaxies, and WFC3 spectroscopy is essential to definitively determine cluster membership for 200 members, without bias with respect to quiescent or SF type. The F125W {rest-frame V-band} imaging is necessary to measure the sizes and morphologies of cluster members. 17-passband broadband imaging spanning UV, optical, near-IR, Spitzer IR and Herschel far-IR is already in hand.

  16. Massive star-forming host galaxies of quasars on Sloan digital sky survey stripe 82

    SciTech Connect

    Matsuoka, Yoshiki; Strauss, Michael A.; Price, Ted N. III; DiDonato, Matthew S.

    2014-01-10

    The stellar properties of about 800 galaxies hosting optically luminous, unobscured quasars at z < 0.6 are analyzed. Deep co-added Sloan Digital Sky Survey (SDSS) images of the quasars on Stripe 82 are decomposed into nucleus and host galaxy using point spread function and Sérsic models. The systematic errors in the measured galaxy absolute magnitudes and colors are estimated to be less than 0.5 mag and 0.1 mag, respectively, with simulated quasar images. The effect of quasar light scattered by the interstellar medium is also carefully addressed. The measured quasar-to-galaxy ratio in total flux decreases toward longer wavelengths, from ∼8 in the u band to ∼1 in the i and z bands. We find that the SDSS quasars are hosted exclusively by massive galaxies (stellar mass M {sub star} > 10{sup 10} M {sub ☉}), which is consistent with previous results for less luminous narrow-line (obscured) active galactic nuclei (AGNs). The quasar hosts are very blue and almost absent on the red sequence, showing stark contrast to the color-magnitude distribution of normal galaxies. The fact that more powerful AGNs reside in galaxies with higher star-formation efficiency may indicate that negative AGN feedback, if it exists, is not concurrent with the most luminous phase of AGNs. We also find positive correlation between the mass of supermassive black holes (SMBHs; M {sub BH}) and host stellar mass, but the M {sub BH}-M {sub star} relation is offset toward large M {sub BH} or small M {sub star} compared to the local relation. While this could indicate that SMBHs grow earlier than do their host galaxies, such an argument is not conclusive, as the effect may be dominated by observational biases.

  17. THE COEVOLUTION OF NUCLEAR STAR CLUSTERS, MASSIVE BLACK HOLES, AND THEIR HOST GALAXIES

    SciTech Connect

    Antonini, Fabio; Barausse, Enrico; Silk, Joseph

    2015-10-10

    Studying how nuclear star clusters (NSCs) form and how they are related to the growth of the central massive black holes (MBHs) and their host galaxies is fundamental for our understanding of the evolution of galaxies and the processes that have shaped their central structures. We present the results of a semi-analytical galaxy formation model that follows the evolution of dark matter halos along merger trees, as well as that of the baryonic components. This model allows us to study the evolution of NSCs in a cosmological context, by taking into account the growth of NSCs due to both dynamical-friction-driven migration of stellar clusters and star formation triggered by infalling gas, while also accounting for dynamical heating from (binary) MBHs. We find that in situ star formation contributes a significant fraction (up to ∼80%) of the total mass of NSCs in our model. Both NSC growth through in situ star formation and that through star cluster migration are found to generate NSC—host galaxy scaling correlations that are shallower than the same correlations for MBHs. We explore the role of galaxy mergers on the evolution of NSCs and show that observational data on NSC—host galaxy scaling relations provide evidence of partial erosion of NSCs by MBH binaries in luminous galaxies. We show that this observational feature is reproduced by our models, and we make predictions about the NSC and MBH occupation fraction in galaxies. We conclude by discussing several implications for theories of NSC formation.

  18. Jellyfish: Observational Properties of Extreme Ram-Pressure Stripping Events in Massive Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Conor, McPartland; Ebeling, Harald; Roediger, Elke

    2015-08-01

    We investigate the physical origin and observational signatures of extreme ram-pressure stripping (RPS) in 63 massive galaxy clusters at z=0.3-0.7, based on data in the F606W passband obtained with the Advanced Camera for Surveys aboard the Hubble Space Telescope. Using a training set of a dozen ``jellyfish" galaxies identified earlier in the same imaging data, we define quantitative morphological criteria to select candidate galaxies which are similar to known cases of RPS. Considering a sample of 16 ``jellyfish" galaxies (10 of which we present for the first time), we visually derive estimates of the projected direction of motion based on dynamical features such as apparent compression shocks and debris trails. Our findings suggest that the observed events occur primarily at large distances from the cluster core and involve infall trajectories featuring high impact parameters. Simple models of cluster growth show that such trajectories are consistent with two scenarios: 1) galaxy infall along filaments; and 2) infall at high velocities (≥1000 km/s) characteristic of cluster mergers. The observed distribution of events is best described by timescales of ˜few Myr in agreement with recent numerical simulations of RPS. The broader areal coverage of the Hubble Frontier Fields should provide an even larger sample of RPS events to determine the relative contributions of infall and cluster mergers. Prompted by the discovery of several jellyfish galaxies whose brightness in the F606W passband rivals or exceeds that of the respective brightest cluster galaxy, we attempt to constrain the luminosity function of galaxies undergoing RPS. The observed significant excess at the bright end compared to the luminosity functions of blue cluster members strongly suggests enhanced star formation, thus challenging theoretical and numerical studies according to which RPS merely displaces existing star-forming regions. In-depth studies of individual objects will help test our

  19. Relaxation and Thermalization in Spiral Galaxies Mediated by Spiral Wave Scattering

    NASA Astrophysics Data System (ADS)

    Hohlfeld, R. G.; Shalit, D.; Comins, N. F.; Sandri, G. V. H.

    1993-12-01

    We have constructed N-body particle-mesh simulations of disk galaxies in which the relaxation times of the simulated disks (as measured by thermalization of the disk, i.e. increase in Toomre's Q parameter) is comparable to the actual relaxation time scale in actual disk galaxies (several tens of rotation periods). These simulations require 1M to 4M particles (1M = 2(20) ), consistent with the work of White and of Comins and Schroeder on the dependence of relaxation time on N. We observe that during the interval when Q is increasing, that the Fourier power associated with spiral modes is large. When Q has risen to its asymptotic value in the simulation, the Fourier power diminishes to a low level. This suggests a scenario in which stars (simulation particles) scatter off the time-varying spiral potential, as suggested by Carlberg and Sellwood. Eventually random velocities of stars increase to a value which quenches the spiral instability. We compare the heating rates in our simulations at observed spiral wave amplitudes to the expected growth rates as given by Carlberg and Sellwood.

  20. Stellar dynamics around a massive black hole - III. Resonant relaxation of razor-thin axisymmetric discs

    NASA Astrophysics Data System (ADS)

    Sridhar, S.; Touma, Jihad R.

    2017-02-01

    We study the resonant relaxation (RR) of an axisymmetric, low-mass (or Keplerian) stellar disc orbiting a more massive black hole (MBH). Our recent work on the general kinetic theory of RR is simplified in the standard manner by the neglect of 'gravitational polarization' and applied to a razor-thin axisymmetric disc. The wake of a stellar orbit is expressed in terms of the angular momenta exchanged with other orbits, and used to derive a kinetic equation for RR under the combined actions of self-gravity, 1 PN and 1.5 PN general relativistic effects of the MBH and an arbitrary external axisymmetric potential. This is a Fokker-Planck equation for the stellar distribution function (DF), wherein the diffusion coefficients are given self-consistently in terms of contributions from apsidal resonances between pairs of stellar orbits. The physical kinetics is studied for the two main cases of interest. (1) 'Lossless' discs in which the MBH is not a sink of stars, and disc mass, angular momentum and energy are conserved: we prove that general H-functions can increase or decrease during RR, but the Boltzmann entropy is (essentially) unique in being a non-decreasing function of time. Therefore, secular thermal equilibria are maximum entropy states, with DFs of the Boltzmann form; the two-ring correlation function at equilibrium is computed. (2) Discs that lose stars to the MBH through an 'empty loss cone': we derive expressions for the MBH feeding rates of mass, angular momentum and energy in terms of the diffusive fluxes at the loss-cone boundaries.

  1. Ophiuchus: An optical view of a very massive cluster of galaxies hidden behind the Milky Way ⋆

    NASA Astrophysics Data System (ADS)

    Durret, F.; Wakamatsu, K.; Nagayama, T.; Adami, C.; Biviano, A.

    2015-11-01

    Context. The Ophiuchus cluster, at a redshift z = 0.0296, is known from X-rays to be one of the most massive nearby clusters, but its optical properties have not been investigated in detail because of its very low Galactic latitude. Aims: We discuss the optical properties of the galaxies in the Ophiuchus cluster, in particular, with the aim of understanding its dynamical properties better. Methods: We have obtained deep optical imaging in several bands with various telescopes, and applied a sophisticated method to model and subtract the contributions of stars to measure galaxy magnitudes as accurately as possible. The colour-magnitude relations obtained show that there are hardly any blue galaxies in Ophiuchus (at least brighter than r' ≤ 19.5), and this is confirmed by the fact that we only detect two galaxies in Hα. We also obtained a number of spectra with ESO-FORS2, which we combined with previously available redshifts. Altogether, we have 152 galaxies with spectroscopic redshifts in the 0.02 ≤ z ≤ 0.04 range, and 89 galaxies with both a redshift within the cluster redshift range and a measured r' band magnitude (limited to the Megacam 1 × 1 deg2 field). Results: A complete dynamical analysis based on the galaxy redshifts available shows that the overall cluster is relaxed and has a mass of 1.1 × 1015 M⊙. The Sernal-Gerbal method detects a main structure and a much smaller substructure, which are not separated in projection. Conclusions: From its dynamical properties derived from optical data, the Ophiuchus cluster seems overall to be a relaxed structure, or at most a minor merger, though in X-rays the central region (radius ~ 150 kpc) may show evidence for merging effects. Based on observations obtained with MegaPrime/MegaCam (program 10AF02), a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the

  2. Towards a census of supercompact massive galaxies in the Kilo Degree Survey

    NASA Astrophysics Data System (ADS)

    Tortora, C.; La Barbera, F.; Napolitano, N. R.; Roy, N.; Radovich, M.; Cavuoti, S.; Brescia, M.; Longo, G.; Getman, F.; Capaccioli, M.; Grado, A.; Kuijken, K. H.; de Jong, J. T. A.; McFarland, J. P.; Puddu, E.

    2016-04-01

    The abundance of compact, massive, early-type galaxies (ETGs) provides important constraints to galaxy formation scenarios. Thanks to the area covered, depth, excellent spatial resolution and seeing, the ESO Public optical Kilo Degree Survey (KiDS), carried out with the VLT Survey Telescope, offers a unique opportunity to conduct a complete census of the most compact galaxies in the Universe. This paper presents a first census of such systems from the first 156 deg2 of KiDS. Our analysis relies on g-, r- and i-band effective radii (Re), derived by fitting galaxy images with point spread function (PSF)-convolved Sérsic models, high-quality photometric redshifts, zphot, estimated from machine learning techniques, and stellar masses, M⋆, calculated from KiDS aperture photometry. After massiveness ({M_{⋆}}≳ 8 × 10^{10} M_{⊙}) and compactness ({R_e}≲ 1.5 kpc in g, r and i bands) criteria are applied, a visual inspection of the candidates plus near-infrared photometry from VIKING-DR1 are used to refine our sample. The final catalogue, to be spectroscopically confirmed, consists of 92 systems in the redshift range z ˜ 0.2-0.7. This sample, which we expect to increase by a factor of 10 over the total survey area, represents the first attempt to select massive supercompact ETGs (MSCGs) in KiDS. We investigate the impact of redshift systematics in the selection, finding that this seems to be a major source of contamination in our sample. A preliminary analysis shows that MSCGs exhibit negative internal colour gradients, consistent with a passive evolution of these systems. We find that the number density of MSCGs is only mildly consistent with predictions from simulations at z > 0.2, while no such system is found at z < 0.2.

  3. A massive, cooling-flow-induced starburst in the core of a luminous cluster of galaxies.

    PubMed

    McDonald, M; Bayliss, 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; Liu, 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

    2012-08-16

    In the cores of some clusters of galaxies 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 centre, 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 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 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 10(45) erg s(-1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.

  4. The Stellar Halos of Massive Elliptical Galaxies. III. Kinematics at Large Radius

    NASA Astrophysics Data System (ADS)

    Raskutti, Sudhir; Greene, Jenny E.; Murphy, Jeremy D.

    2014-05-01

    We present a two-dimensional kinematic analysis out to ~2-5 effective radii (Re ) of 33 massive elliptical galaxies with stellar velocity dispersions σ > 150 km s-1. Our observations were taken using the Mitchell Spectrograph (formerly VIRUS-P), a spectrograph with a large 107 × 107 arcsec2 field of view that allows us to construct robust, spatially resolved kinematic maps of V and σ for each galaxy extending to at least 2 Re . Using these maps, we study the radial dependence of the stellar angular momentum and other kinematic properties. We see the familiar division between slow and fast rotators persisting out to a large radius in our sample. Centrally slow rotating galaxies, which are almost universally characterized by some form of kinematic decoupling or misalignment, remain slowly rotating in their halos. The majority of fast-rotating galaxies show either increases in specific angular momentum outward or no change beyond Re . The generally triaxial nature of the slow rotators suggests that they formed through mergers, consistent with a "two-phase" picture of elliptical galaxy formation. However, we do not observe the sharp transitions in kinematics proposed in the literature as a signpost of moving from central dissipationally formed components to outer accretion-dominated halos.

  5. The stellar halos of massive elliptical galaxies. III. Kinematics at large radius

    SciTech Connect

    Raskutti, Sudhir; Greene, Jenny E.; Murphy, Jeremy D.

    2014-05-01

    We present a two-dimensional kinematic analysis out to ∼2-5 effective radii (R{sub e} ) of 33 massive elliptical galaxies with stellar velocity dispersions σ > 150 km s{sup –1}. Our observations were taken using the Mitchell Spectrograph (formerly VIRUS-P), a spectrograph with a large 107 × 107 arcsec{sup 2} field of view that allows us to construct robust, spatially resolved kinematic maps of V and σ for each galaxy extending to at least 2 R{sub e} . Using these maps, we study the radial dependence of the stellar angular momentum and other kinematic properties. We see the familiar division between slow and fast rotators persisting out to a large radius in our sample. Centrally slow rotating galaxies, which are almost universally characterized by some form of kinematic decoupling or misalignment, remain slowly rotating in their halos. The majority of fast-rotating galaxies show either increases in specific angular momentum outward or no change beyond R{sub e} . The generally triaxial nature of the slow rotators suggests that they formed through mergers, consistent with a 'two-phase' picture of elliptical galaxy formation. However, we do not observe the sharp transitions in kinematics proposed in the literature as a signpost of moving from central dissipationally formed components to outer accretion-dominated halos.

  6. The MASSIVE Survey - V. Spatially resolved stellar angular momentum, velocity dispersion, and higher moments of the 41 most massive local early-type galaxies

    NASA Astrophysics Data System (ADS)

    Veale, Melanie; Ma, Chung-Pei; Thomas, Jens; Greene, Jenny E.; McConnell, Nicholas J.; Walsh, Jonelle; Ito, Jennifer; Blakeslee, John P.; Janish, Ryan

    2017-01-01

    We present spatially resolved two-dimensional stellar kinematics for the 41 most massive early-type galaxies (ETGs; MK ≲ -25.7 mag, stellar mass M* ≳ 1011.8 M⊙) of the volume-limited (D < 108 Mpc) MASSIVE survey. For each galaxy, we obtain high-quality spectra in the wavelength range of 3650-5850 Å from the 246-fibre Mitchell integral-field spectrograph at McDonald Observatory, covering a 107 arcsec × 107 arcsec field of view (often reaching 2 to 3 effective radii). We measure the 2D spatial distribution of each galaxy's angular momentum (λ and fast or slow rotator status), velocity dispersion (σ), and higher order non-Gaussian velocity features (Gauss-Hermite moments h3 to h6). Our sample contains a high fraction (˜80 per cent) of slow and non-rotators with λ ≲ 0.2. When combined with the lower mass ETGs in the ATLAS3D survey, we find the fraction of slow rotators to increase dramatically with galaxy mass, reaching ˜50 per cent at MK ˜ -25.5 mag and ˜90 per cent at MK ≲ -26 mag. All of our fast rotators show a clear anticorrelation between h3 and V/σ, and the slope of the anticorrelation is steeper in more round galaxies. The radial profiles of σ show a clear luminosity and environmental dependence: the 12 most luminous galaxies in our sample (MK ≲ -26 mag) are all brightest cluster/group galaxies (except NGC 4874) and all have rising or nearly flat σ profiles, whereas five of the seven `isolated' galaxies are all fainter than MK = -25.8 mag and have falling σ. All of our galaxies have positive average h4; the most luminous galaxies have average h4 ˜ 0.05, while less luminous galaxies have a range of values between 0 and 0.05. Most of our galaxies show positive radial gradients in h4, and those galaxies also tend to have rising σ profiles. We discuss the implications for the relationship among dynamical mass, σ, h4, and velocity anisotropy for these massive galaxies.

  7. Luminosity function of [O II] emission-line galaxies in the MassiveBlack-II simulation

    NASA Astrophysics Data System (ADS)

    Park, KwangHo; Di Matteo, Tiziana; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M.; Feng, Yu; Khandai, Nishikanta

    2015-11-01

    We examine the luminosity function (LF) of [O II] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at 0.06 ≤ z ≤ 3.0 using the [O II] emission line luminosity L([O II]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [O II] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([O II]) = 1043.0 erg s-1 while the low redshifts (z ≤ 0.3) show an excess in the prediction of bright [O II] galaxies, but still displaying a good match with observations below L([O II]) = 1041.6 erg s-1. Based on the validity in reproducing the properties of [O II] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [O II] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from -3 to -2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)-1 at z ≤ 2 while the faint end evolves as ˜3(z + 1)-1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [O III] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. Finally, we show that the auto-correlation function of [O II] and [O III] emitting galaxies shows a rapid evolution from z = 2 to 1.

  8. Redshift evolution of the dynamical properties of massive galaxies from SDSS-III/BOSS

    SciTech Connect

    Beifiori, Alessandra; Saglia, Roberto P.; Bender, Ralf; Senger, Robert; Thomas, Daniel; Maraston, Claudia; Steele, Oliver; Masters, Karen L.; Pforr, Janine; Tojeiro, Rita; Johansson, Jonas; Nichol, Robert C.; Chen, Yan-Mei; Wake, David; Bolton, Adam; Brownstein, Joel R.; Leauthaud, Alexie; Schneider, Donald P.; Skibba, Ramin; Pan, Kaike; and others

    2014-07-10

    We study the redshift evolution of the dynamical properties of ∼180, 000 massive galaxies from SDSS-III/BOSS combined with a local early-type galaxy sample from SDSS-II in the redshift range 0.1 ≤ z ≤ 0.6. The typical stellar mass of this sample is M{sub *} ∼2 × 10{sup 11} M{sub ☉}. We analyze the evolution of the galaxy parameters effective radius, stellar velocity dispersion, and the dynamical to stellar mass ratio with redshift. As the effective radii of BOSS galaxies at these redshifts are not well resolved in the Sloan Digital Sky Survey (SDSS) imaging we calibrate the SDSS size measurements with Hubble Space Telescope/COSMOS photometry for a sub-sample of galaxies. We further apply a correction for progenitor bias to build a sample which consists of a coeval, passively evolving population. Systematic errors due to size correction and the calculation of dynamical mass are assessed through Monte Carlo simulations. At fixed stellar or dynamical mass, we find moderate evolution in galaxy size and stellar velocity dispersion, in agreement with previous studies. We show that this results in a decrease of the dynamical to stellar mass ratio with redshift at >2σ significance. By combining our sample with high-redshift literature data, we find that this evolution of the dynamical to stellar mass ratio continues beyond z ∼ 0.7 up to z > 2 as M{sub dyn}/M{sub *} ∼(1 + z){sup –0.30±0.12}, further strengthening the evidence for an increase of M{sub dyn}/M{sub *} with cosmic time. This result is in line with recent predictions from galaxy formation simulations based on minor merger driven mass growth, in which the dark matter fraction within the half-light radius increases with cosmic time.

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

    DOE PAGES

    Park, KwangHo; Khandai, Nishikanta; Matteo, Tiziana Di; ...

    2015-09-18

    We examine the luminosity function (LF) of [OII] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at 0.06 ≤ z ≤ 3.0 using the [OII] emission line luminosity L([OII]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [OII] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([OII]) = 1043.0 erg s–1 while the low redshifts (z ≤ 0.3) show an excessmore » in the prediction of bright [OII] galaxies, but still displaying a good match with observations below L([OII]) = 1041.6 erg s–1. Based on the validity in reproducing the properties of [OII] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [OII] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from –3 to –2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)–1 at z ≤ 2 while the faint end evolves as ~3(z + 1)–1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [OIII] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. As a result, we show that the auto-correlation function of [OII] and [OIII] emitting galaxies shows a rapid evolution from z = 2 to 1.« less

  10. The MassiveBlack-II simulation: the evolution of haloes and galaxies to z ˜ 0

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    We investigate the properties of haloes, galaxies and black holes to z = 0 in the high-resolution hydrodynamical simulation MassiveBlack-II (MBII) which evolves a Λ cold dark matter cosmology in a comoving volume Vbox = (100 Mpc h-1)3. MBII is the highest resolution simulation of this size which includes a self-consistent model for star formation, black hole accretion and associated feedback. We provide a simulation browser web application which enables interactive search and tagging of the MBII data set and publicly release our galaxy catalogues. We find that baryons affect strongly the halo mass function (MF), with 20-33 per cent change in the halo abundance below the knee of the MF (Mhalo < 1013.2 M⊙ h-1 at z = 0) when compared to dark-matter-only simulations. We provide a fitting function for the halo MF out to redshift z = 11 and discuss its limitations. We study the halo occupation distribution and clustering of galaxies, in particular the evolution and scale dependence of stochasticity and bias finding reasonable agreement with observational data. The shape of the cosmic spectral energy distribution of galaxies in MBII is consistent with observations, but lower in amplitude. The Galaxy stellar mass function (GSMF) function is broadly consistent with observations at z ≥ 2. At z < 2, the population of passive low-mass (M* < 109 M⊙) galaxies in MBII makes the GSMF too steep compared to observations whereas at the high-mass end (M* > 1011 M⊙) galaxies hosting bright AGNs make significant contributions to the GSMF. The quasar bolometric luminosity function is also largely consistent with observations. We note however that more efficient AGN feedback is necessary for the largest, rarest objects/clusters at low redshifts.

  11. FIRST RESULTS FROM THE 3D-HST SURVEY: THE STRIKING DIVERSITY OF MASSIVE GALAXIES AT z > 1

    SciTech Connect

    Van Dokkum, Pieter G.; Nelson, Erica; Skelton, Rosalind E.; Bezanson, Rachel; Lundgren, Britt; Brammer, Gabriel; Fumagalli, Mattia; Franx, Marijn; Patel, Shannon; Labbe, Ivo; Rix, Hans-Walter; Schmidt, Kasper B.; Da Cunha, Elisabete; Kriek, Mariska; Bian Fuyan; Fan Xiaohui; Erb, Dawn K.; Foerster Schreiber, Natascha; Illingworth, Garth D.; Magee, Dan; and others

    2011-12-10

    We present first results from the 3D-HST program, a near-IR spectroscopic survey performed with the Wide Field Camera 3 (WFC3) on the HST. We have used 3D-HST spectra to measure redshifts and H{alpha} equivalent widths (EW{sub H{alpha}}) for a complete, stellar mass-limited sample of 34 galaxies at 1 < z < 1.5 with M{sub star} > 10{sup 11} M{sub Sun} in the COSMOS, GOODS, and AEGIS fields. We find that a substantial fraction of massive galaxies at this epoch are forming stars at a high rate: the fraction of galaxies with EW{sub H{alpha}} >10 A is 59%, compared to 10% among Sloan Digital Sky Survey galaxies of similar masses at z = 0.1. Galaxies with weak H{alpha} emission show absorption lines typical of 2-4 Gyr old stellar populations. The structural parameters of the galaxies, derived from the associated WFC3 F140W imaging data, correlate with the presence of H{alpha}; quiescent galaxies are compact with high Sersic index and high inferred velocity dispersion, whereas star-forming galaxies are typically large two-armed spiral galaxies, with low Sersic index. Some of these star-forming galaxies might be progenitors of the most massive S0 and Sa galaxies. Our results challenge the idea that galaxies at fixed mass form a homogeneous population with small scatter in their properties. Instead, we find that massive galaxies form a highly diverse population at z > 1, in marked contrast to the local universe.

  12. The impact of mechanical AGN feedback on the formation of massive early-type galaxies

    NASA Astrophysics Data System (ADS)

    Choi, Ena; Ostriker, Jeremiah P.; Naab, Thorsten; Oser, Ludwig; Moster, Benjamin P.

    2015-06-01

    We employ cosmological hydrodynamical simulations to investigate the effects of AGN feedback on the formation of massive galaxies with present-day stellar masses of M_stel= 8.8 × 10^{10}-6.0 × 10^{11} M_{⊙}. Using smoothed particle hydrodynamics simulations with a pressure-entropy formulation that allows an improved treatment of contact discontinuities and fluid mixing, we run three sets of simulations of 20 haloes with different AGN feedback models: (1) no feedback, (2) thermal feedback, and (3) mechanical and radiation feedback. We assume that seed black holes are present at early cosmic epochs at the centre of emerging dark matter haloes and trace their mass growth via gas accretion and mergers with other black holes. Both feedback models successfully recover the observed MBH-σ relation and black hole-to-stellar mass ratio for simulated central early-type galaxies. The baryonic conversion efficiencies are reduced by a factor of 2 compared to models without any AGN feedback at all halo masses. However, massive galaxies simulated with thermal AGN feedback show a factor of ˜10-100 higher X-ray luminosities than observed. The mechanical/radiation feedback model reproduces the observed correlation between X-ray luminosities and velocity dispersion, e.g. for galaxies with σ = 200 km s- 1, the X-ray luminosity is reduced from 1042 erg s- 1 to 1040 erg s- 1. It also efficiently suppresses late-time star formation, reducing the specific star formation rate from 10-10.5 yr- 1 to 10-14 yr- 1 on average and resulting in quiescent galaxies since z = 2, whereas the thermal feedback model shows higher late-time in situ star formation rates than observed.

  13. Properties of galaxies around AGNs with the most massive supermassive black holes revealed by clustering analysis

    NASA Astrophysics Data System (ADS)

    Shirasaki, Yuji; Komiya, Yutaka; Ohishi, Masatoshi; Mizumoto, Yoshihiko

    2016-04-01

    We present results of the clustering analysis between active galactic nuclei (AGNs) and galaxies at redshift 0.1-1.0, which was performed to investigate the properties of galaxies associated with the AGNs and reveal the nature of the fueling mechanism of supermassive black holes (SMBHs). We used 8059 AGNs/quasi-stellar objects (QSOs) for which virial masses of individual SMBHs were measured, and divided them into four mass groups.Cross-correlation analysis was performed to reconfirm our previous result that cross-correlation length increases with SMBH mass MBH; we obtained consistent results. A linear bias of AGN for each mass group was measured as 1.47 for MBH = 107.5-108.2 M⊙ and 3.08 for MBH = 109-1010 M⊙. The averaged color and luminosity distributions of galaxies around the AGNs/QSOs were also derived for each mass group. The galaxy color Dopt-IR was estimated from a spectral energy distribution (SED) constructed from a catalog derived by merging the Sloan Digital Sky Survey (SDSS) and the UKIRT Infrared Deep Sky Survey (UKIDSS) catalogs. The distributions of color and luminosity were derived by a subtraction method, which does not require redshift information of galaxies. The main results of this work are as follows. (1) A linear bias increases by a factor of two from the lower-mass group to the highest-mass group. (2) The environment around AGNs with the most massive SMBHs (MBH > 109 M⊙) is dominated by red sequence galaxies. (3) Marginal indication of decline in luminosity function at dimmer side of MIR > -19.5 is found for galaxies around AGNs with MBH = 108.2-109 M⊙ and nearest redshift group (z = 0.1-0.3). These results indicate that AGNs with the most massive SMBHs reside in haloes where a large fraction of galaxies have been transited to the red sequence. The accretion of hot halo gas as well as recycled gas from evolving stars can be one of the plausible mechanisms to fuel the SMBHs above ˜ 109 M⊙.

  14. A Wide Area Survey for High-Redshift Massive Galaxies. II. Near-Infrared Spectroscopy of BzK-Selected Massive Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Onodera, Masato; Arimoto, Nobuo; Daddi, Emanuele; Renzini, Alvio; Kong, Xu; Cimatti, Andrea; Broadhurst, Tom; Alexander, Dave M.

    2010-05-01

    Results are presented from near-infrared spectroscopic observations of a sample of BzK-selected, massive star-forming galaxies (sBzKs) at 1.5 < z < 2.3 that were obtained with OHS/CISCO at the Subaru telescope and with SINFONI at the Very Large Telescope. Among the 28 sBzKs observed, Hα emission was detected in 14 objects, and for 11 of them the [N II] λ6583 flux was also measured. Multiwavelength photometry was also used to derive stellar masses and extinction parameters, whereas Hα and [N II] emissions have allowed us to estimate star formation rates (SFRs), metallicities, ionization mechanisms, and dynamical masses. In order to enforce agreement between SFRs from Hα with those derived from rest-frame UV and mid-infrared, additional obscuration for the emission lines (that originate in H II regions) was required compared to the extinction derived from the slope of the UV continuum. We have also derived the stellar mass-metallicity relation, as well as the relation between stellar mass and specific SFR (SSFR), and compared them to the results in other studies. At a given stellar mass, the sBzKs appear to have been already enriched to metallicities close to those of local star-forming galaxies of similar mass. The sBzKs presented here tend to have higher metallicities compared to those of UV-selected galaxies, indicating that near-infrared selected galaxies tend to be a chemically more evolved population. The sBzKs show SSFRs that are systematically higher, by up to ~2 orders of magnitude, compared to those of local galaxies of the same mass. The empirical correlations between stellar mass and metallicity, and stellar mass and SSFR are then compared with those of evolutionary population synthesis models constructed either with the simple closed-box assumption, or within an infall scenario. Within the assumptions that are built-in such models, it appears that a short timescale for the star formation (sime100 Myr) and large initial gas mass appear to be required

  15. OT2_fwyrowsk_3: A Water survey of massive star forming clumps in the inner Galaxy

    NASA Astrophysics Data System (ADS)

    Wyrowski, F.

    2011-09-01

    Water, as a dominant form of oxygen, the most abundant element in the universe after H and He, controls the chemistry of many other species. It is a unique diagnostic of warm gas and energetic processes taking place during star formation. We therefore propose to exploit the unique opportunity of Herschel to study water in large, statistically significant, flux limited samples of massive star forming regions detected in the recently completed ATLASGAL submm dust continuum survey of the inner Galactic plane. In the last years, our view of massive star forming regions has dramatically changed by Galactic plane surveys covering cm to IR wavelengths. These surveys enable us for the first time to study ALL evolutionary stages of massive star formation (MSF) in an unbiased way. Water, acting as a natural filter for warm, dense gas, allows to probe the chemical and physical conditions in all of these stages close to where the massive stars are forming or just have been formed. ATLASGAL observed submm dust continuum emission as best tracer of the earliest phases of MSF since it is directly probing the material from which the stars form. As a large unbiased survey it provide the statistical base to study the scarce and short-living protoclusters as the origin of the massive stars and the richest clusters in the Galaxy and supplies us with a legacy value sample of MSF regions for the water follow ups. Water is typically seen with strongly increased abundances in broad line wings, providing a new, sensitive probe of shocked outflowing gas. In addition, the envelope is probed in a combination of absorption and emission with a clear jump in abundance in the warm inner regions close to the forming massive stars. Only Herschel can provide a water survey of a large sample of ATLASGAL selected sources to study water through the evolution of massive star forming regions with a statistically significant sample size.

  16. Gas Content and Star Formation Efficiency of Massive Main Sequence Galaxies at z~3-4

    NASA Astrophysics Data System (ADS)

    Schinnerer, Eva; Groves, Brent; Karim, Alexander; Sargent, Mark T.; Oesch, Pascal; Le Fevre, Olivier; Tasca, Lidia; Magnelli, Benjamin; Cassata, Paolo; Smolcic, Vernesa

    2016-01-01

    Recent observations have shown that the neutral gas content and star formation efficiency of massive (with log(stellar masses) > 10), normal star forming galaxies, i.e. they reside on the main sequence of star forming galaxies, are steadily decreasing from the peak of star formation activity (at redshifts of z~2) till today. This decrease is coincident with the observed decline in the cosmic star formation rate density over this time range. However, only few observations have probed the evolution of the gas content and star formation efficiency beyond this peak epoch when the cosmic star formation rate density has been increasing, i.e. at redshifts of z~3-4.We will present new ALMA rest-frame 250um continuum detections of 45 massive, normal star forming galaxies in this critical redshift interval selected in the COSMOS deep field. Using the sub-mm continnum as proxy for the cold neutral gas content, we find gas mass fractions and depletions similar to those reported during the peak epoch of star formation. We will discuss our findings in the context of results from lower redshift observations and model expectations.

  17. The XMM Cluster Survey: A Massive Galaxy Cluster at z = 1.45

    SciTech Connect

    Stanford, S A; Romer, A K; Sabirli, K; Davidson, M; Hilton, M; Viana, P P; Collins, C A; Kay, S T; Liddle, A R; Mann, R G; Miller, C J; Nichol, R C; West, M J; Conselice, C J; Spinrad, H; Stern, D; Bundy, K

    2006-05-24

    We report the discovery of XMMXCS J2215.9-1738, a massive galaxy cluster at z = 1.45, which was found in the XMM Cluster Survey. The cluster candidate was initially identified as an extended X-ray source in archival XMM data. Optical spectroscopy shows that 6 galaxies within a {approx}60 arcsec diameter region lie at z = 1.45 {+-} 0.01. Model fits to the X-ray spectra of the extended emission yield kT = 7.4{sub -1.8}{sup +2.7} keV (90% confidence); if there is an undetected central X-ray point source then kT = 6.5{sub -1.8}{sup +2.6} keV. The bolometric X-ray luminosity is L{sub x} = 4.4{sub -0.6}{sup +0.8} x 10{sup 44} ergs s{sup -1} over a 2 Mpc radial region. The measured T{sub x}, which is the highest for any known cluster at z > 1, suggests that this cluster is relatively massive for such a high redshift. The redshift of XMMXCS J2215.9-1738 is the highest currently known for a spectroscopically-confirmed cluster of galaxies.

  18. Detecting Massive, High-Redshift Galaxy Clusters Using the Thermal Sunyaev-Zel'dovich Effect

    NASA Astrophysics Data System (ADS)

    Adams, Carson; Steinhardt, Charles L.; Loeb, Abraham; Karim, Alexander; Staguhn, Johannes; Erler, Jens; Capak, Peter L.

    2017-01-01

    We develop the thermal Sunyaev-Zel'dovich (SZ) effect as a direct astrophysical measure of the mass distribution of dark matter halos. The SZ effect increases with cosmological distance, a unique astronomical property, and is highly sensitive to halo mass. We find that this presents a powerful methodology for distinguishing between competing models of the halo mass function distribution, particularly in the high-redshift domain just a few hundred million years after the Big Bang. Recent surveys designed to probe this epoch of initial galaxy formation such as CANDELS and SPLASH report an over-abundance of highly massive halos as inferred from stellar ultraviolet (UV) luminosities and the stellar mass to halo mass ratio estimated from nearby galaxies. If these UV luminosity to halo mass relations hold to high-redshift, observations estimate several orders of magnitude more highly massive halos than predicted by hierarchical merging and the standard cosmological paradigm. Strong constraints on the masses of these galaxy clusters are essential to resolving the current tension between observation and theory. We conclude that detections of thermal SZ sources are plausible at high-redshift only for the halo masses inferred from observation. Therefore, future SZ surveys will provide a robust determination between theoretical and observational predictions.

  19. The Impact of Massive Starbursts on the Chemical Evolution of Galaxies

    NASA Astrophysics Data System (ADS)

    Kobulnicky, Henry A.

    Young, compact star clusters containing hundreds to thousands of the most massive OB and Wolf-Rayet type stars are common features of actively star-forming galaxies. Radio-wave H scI and millimeter-wave CO aperture synthesis observations of the interstellar gas in several such systems reveal strong evidence for recent collisions or mergers with other galaxies which probably triggered the present burst. Most of the oxygen in the universe, and to a lesser extent carbon and nitrogen, is synthesized within massive stars and returned to the interstellar gas by stellar winds and supernova explosions as these stars evolve. Yet, spatially-resolved spectroscopic investigations of the ionized gas in several starburst galaxies fail to find any sign of recent nucleosynthesis products in the vicinity of evolved starclusters. The chemical abundances of O, N, He, and probably C, appear very homogeneous on scales of ~1 kpc or less, despite the fact that models of the chemical enrichment expected from a single 106/ Msolar burst show that large localized chemical enhancements should occur. That there is no evidence of localized chemical enrichment within the H scII regions of most metal-poor galaxies suggests the recently-released heavy elements are 'hiding' either in a hot, 106 phase or in a cool neutral atomic or molecular phase. In either case, the timescale for visible enrichment in galaxies appears to exceed the lifetimes of the H scII regions and the spatial scales must exceed 1 kpc. These data are inconsistent with the H scII region 'self-enrichment' or 'pollution' hypothesis. For now, heavy elements produced in starbursts can be considered 'missing', but upcoming X-ray observatories may be able to establish their physical phase and location. Hubble Space Telescope spectroscopic measurements show evidence for a correlation between C and N abundances among galaxies with similar metallicity (O/H). The existence of such a correlation implies that C and N production mechanisms

  20. Dark energy, co-evolution of massive black holes with galaxies, and ASTROD-GW

    NASA Astrophysics Data System (ADS)

    Ni, Wei-Tou

    2013-02-01

    The detection of low frequency band (100 nHz-100 mHz) and very low frequency band (300 pHz-100 nHz) gravitational waves (GWs) is important for exploration of the equation of state of dark energy and the co-evolution of massive black holes (MBHs) with galaxies. Most galaxies are believed to have a massive black hole in the galactic core. In the formation of these black holes, merging and accretion are the two main processes. Merging of massive black holes generate GWs which could be detected by space GW detectors and Pulsar Timing Arrays (PTAs) to cosmological distances. LISA (Laser-Interferometric Space Antenna) is most sensitive to the frequency band 1 mHz-100 mHz, ASTROD-GW (ASTROD [Astrodynamical Space Test of Relativity using Optical Devices] optimized for Gravitational Wave detection) is most sensitive to the frequency band 100 nHz-1 mHz and PTAs are most sensitive to the frequency band 300 pHz-100 nHz. In this paper, we discuss the sensitivities and outlooks of detection of GWs from binary massive black holes in these frequency bands with an emphasis on ASTROD-GW. The GWs generated by the inspirals, merging and subsequent ringdowns of binary black holes are standard sirens to the cosmological distance. Using GW observations, we discuss the methods for determining the equation of state of dark energy and for testing the co-evolution models of massive black holes. ASTROD-GW is an optimization of ASTROD to focus on the goal of detection of GWs. The mission orbits of the 3 spacecraft forming a nearly equilateral triangular array are chosen to be near the Sun-Earth Lagrange points L3, L4 and L5. The 3 spacecraft range interferometrically with one another with arm length about 260 million kilometers. With 52 times longer in arm length compared to that of LISA, the strain detection sensitivity is 52 times better toward larger wavelength. The scientific aim is focused for gravitational wave detection at low frequency. The science goals include detection of GWs from

  1. Detection of enhancement in number densities of background galaxies due to magnification by massive galaxy clusters

    DOE PAGES

    Chiu, I.; Dietrich, J. P.; Mohr, J.; ...

    2016-02-18

    We present a detection of the enhancement in the number densities of background galaxies induced from lensing magnification and use it to test the Sunyaev-Zel'dovich effect (SZE) inferred masses in a sample of 19 galaxy clusters with median redshift z≃0.42 selected from the South Pole Telescope SPT-SZ survey. Two background galaxy populations are selected for this study through their photometric colours; they have median redshifts zmedian≃0.9 (low-z background) and zmedian≃1.8 (high-z background). Stacking these populations, we detect the magnification bias effect at 3.3σ and 1.3σ for the low- and high-z backgrounds, respectively. We fit NFW models simultaneously to all observedmore » magnification bias profiles to estimate the multiplicative factor η that describes the ratio of the weak lensing mass to the mass inferred from the SZE observable-mass relation. We further quantify systematic uncertainties in η resulting from the photometric noise and bias, the cluster galaxy contamination and the estimations of the background properties. The resulting η for the combined background populations with 1σ uncertainties is 0.83 ± 0.24(stat) ± 0.074(sys), indicating good consistency between the lensing and the SZE-inferred masses. We also use our best-fit η to predict the weak lensing shear profiles and compare these predictions with observations, showing agreement between the magnification and shear mass constraints. Our work demonstrates the promise of using the magnification as a complementary method to estimate cluster masses in large surveys.« less

  2. Detection of enhancement in number densities of background galaxies due to magnification by massive galaxy clusters

    SciTech Connect

    Chiu, I.; Dietrich, J. P.; Mohr, J.; Applegate, D. E.; Benson, B. A.; Bleem, L. E.; Bayliss, M. B.; Bocquet, S.; Carlstrom, J. E.; Capasso, R.; Desai, S.; Gangkofner, C.; Gonzalez, A. H.; Gupta, N.; Hennig, C.; Hoekstra, H.; von der Linden, A.; Liu, J.; McDonald, M.; Reichardt, C. L.; Saro, A.; Schrabback, T.; Strazzullo, V.; Stubbs, C. W.; Zenteno, A.

    2016-02-18

    We present a detection of the enhancement in the number densities of background galaxies induced from lensing magnification and use it to test the Sunyaev-Zel'dovich effect (SZE) inferred masses in a sample of 19 galaxy clusters with median redshift z≃0.42 selected from the South Pole Telescope SPT-SZ survey. Two background galaxy populations are selected for this study through their photometric colours; they have median redshifts zmedian≃0.9 (low-z background) and zmedian≃1.8 (high-z background). Stacking these populations, we detect the magnification bias effect at 3.3σ and 1.3σ for the low- and high-z backgrounds, respectively. We fit NFW models simultaneously to all observed magnification bias profiles to estimate the multiplicative factor η that describes the ratio of the weak lensing mass to the mass inferred from the SZE observable-mass relation. We further quantify systematic uncertainties in η resulting from the photometric noise and bias, the cluster galaxy contamination and the estimations of the background properties. The resulting η for the combined background populations with 1σ uncertainties is 0.83 ± 0.24(stat) ± 0.074(sys), indicating good consistency between the lensing and the SZE-inferred masses. We also use our best-fit η to predict the weak lensing shear profiles and compare these predictions with observations, showing agreement between the magnification and shear mass constraints. Our work demonstrates the promise of using the magnification as a complementary method to estimate cluster masses in large surveys.

  3. Galaxy populations in the 26 most massive galaxy clusters in the South Pole Telescope SPT-SZ survey

    NASA Astrophysics Data System (ADS)

    Zenteno, A.; Mohr, J. J.; Desai, S.; Stalder, B.; Saro, A.; Dietrich, J. P.; Bayliss, M.; Bocquet, S.; Chiu, I.; Gonzalez, A. H.; Gangkofner, C.; Gupta, N.; Hlavacek-Larrondo, J.; McDonald, M.; Reichardt, C.; Rest, A.

    2016-10-01

    We present a study of the optical properties of the 26 most massive galaxy clusters within the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) 2500 deg2 survey spanning the redshift range 0.10 < z < 1.13. We measure the radial profiles, the luminosity functions (LFs), and the halo occupation numbers (HONs) using optical data of typical depth m* + 2. The stacked radial profiles are consistent with a Navarro-Frenk-White profile of concentration 2.84^{+0.40}_{-0.37} for the red sequence (RS) and 2.36^{+0.38}_{-0.35} for the total population. Stacking the data in multiple redshift bins shows slight redshift evolution in the concentration when both the total population is used, and when only RS galaxies are used (at 2.1σ and 2.8σ, respectively). The stacked LF shows a faint end slope α = -1.06^{+0.04}_{-0.03} for the total and α = -0.80^{+0.04}_{-0.03} for the RS population. The redshift evolution of m* is consistent with a passively evolving composite stellar population (CSP) model. Adopting the CSP model predictions, we explore the redshift evolution of the Schechter parameters α and φ*. We find α for the total population to be consistent with no evolution (0.3σ), and mildly significant evidence of evolution for the red galaxies (1.1-2.1σ). The data show that the density φ*/E2(z) decreases with redshift, in tension with the self-similar expectation at a 2.4σ level for the total population. The measured HON-mass relation has a lower normalization than previous low redshift studies. Finally, our data support HON redshift evolution at a 2.1σ level, with clusters at higher redshift containing fewer galaxies than their low-z counterparts.

  4. THE FUNDAMENTAL PLANE OF MASSIVE QUIESCENT GALAXIES OUT TO z ∼ 2

    SciTech Connect

    Van de Sande, Jesse; Franx, Marijn; Kriek, Mariska; Bezanson, Rachel; Van Dokkum, Pieter G.

    2014-10-01

    The Fundamental Plane (FP) of early-type galaxies, relating the effective radius, velocity dispersion, and surface brightness, has long been recognized as a unique tool for analyzing galaxy structure and evolution. With the discovery of distant quiescent galaxies and the introduction of high sensitivity near-infrared spectrographs, it is now possible to explore the FP out to z ∼ 2. In this Letter we study the evolution of the FP out to z ∼ 2 using kinematic measurements of massive quiescent galaxies (M {sub *} > 10{sup 11} M {sub ☉}). We find preliminary evidence for the existence of an FP out to z ∼ 2. The scatter of the FP, however, increases from z ∼ 0 to z ∼ 2, even when taking into account the larger measurement uncertainties at higher redshifts. We find a strong evolution of the zero point from z ∼ 2 to z ∼ 0: Δlog{sub 10} M/L{sub g} ∝(– 0.49 ± 0.03)z. In order to assess whether our spectroscopic sample is representative of the early-type galaxy population at all redshifts, we compare their rest-frame g – z colors with those from a larger mass complete sample of quiescent galaxies. At z > 1 we find that the spectroscopic sample is bluer. We use the color offsets to estimate a mass-to-light ratio (M/L) correction. The implied FP zero point evolution after correction is significantly smaller: Δlog{sub 10} M/L{sub g} ∝(– 0.39 ± 0.02)z. This is consistent with an apparent formation redshift of z{sub form}=6.62{sub −1.44}{sup +3.19} for the underlying population, ignoring the effects of progenitor bias. A more complete spectroscopic sample is required at z ∼ 2 to properly measure the M/L evolution from the FP evolution.

  5. Torque-limited Growth of Massive Black Holes in Galaxies across Cosmic Time

    NASA Astrophysics Data System (ADS)

    Anglés-Alcázar, Daniel; Özel, Feryal; Davé, Romeel; Katz, Neal; Kollmeier, Juna A.; Oppenheimer, Benjamin D.

    2015-02-01

    We combine cosmological hydrodynamic simulations with analytic models to evaluate the role of galaxy-scale gravitational torques on the evolution of massive black holes at the centers of star-forming galaxies. We confirm and extend our earlier results to show that torque-limited growth yields black holes and host galaxies evolving on average along the M BH-M bulge relation from early times down to z = 0 and that convergence onto the scaling relation occurs independent of the initial conditions and with no need for mass averaging through mergers or additional self-regulation processes. Smooth accretion dominates the long-term evolution, with black hole mergers with mass ratios gsim 1:5 representing typically a small fraction of the total growth. Winds from the accretion disk are required to eject significant mass to suppress black hole growth, but there is no need for coupling this wind to galactic-scale gas to regulate black holes in a nonlinear feedback loop. Torque-limited growth yields a close-to-linear < \\dot{M}_BH > \\propto star formation rate (SFR) relation for the black hole accretion rate averaged over galaxy evolution timescales. However, the SFR-AGN connection has significant scatter owing to strong variability of black hole accretion at all resolved timescales. Eddington ratios can be described by a broad lognormal distribution with median value evolving roughly as λMSvprop(1 + z)1.9, suggesting a main sequence for black hole growth similar to the cosmic evolution of specific SFRs. Our results offer an attractive scenario consistent with available observations in which cosmological gas infall and transport of angular momentum in the galaxy by gravitational instabilities regulate the long-term co-evolution of black holes and star-forming galaxies.

  6. Jellyfish: the origin and distribution of extreme ram-pressure stripping events in massive galaxy clusters

    NASA Astrophysics Data System (ADS)

    McPartland, Conor; Ebeling, Harald; Roediger, Elke; Blumenthal, Kelly

    2016-01-01

    We investigate the observational signatures and physical origin of ram-pressure stripping (RPS) in 63 massive galaxy clusters at z = 0.3-0.7, based on images obtained with the Hubble Space Telescope. Using a training set of a dozen `jellyfish' galaxies identified earlier in the same imaging data, we define morphological criteria to select 211 additional, less obvious cases of RPS. Spectroscopic follow-up observations of 124 candidates so far confirmed 53 as cluster members. For the brightest and most favourably aligned systems, we visually derive estimates of the projected direction of motion based on the orientation of apparent compression shocks and debris trails. Our findings suggest that the onset of these events occurs primarily at large distances from the cluster core (>400 kpc), and that the trajectories of the affected galaxies feature high-impact parameters. Simple models show that such trajectories are highly improbable for galaxy infall along filaments but common for infall at high velocities, even after observational biases are accounted for, provided the duration of the resulting RPS events is ≲500 Myr. We thus tentatively conclude that extreme RPS events are preferentially triggered by cluster mergers, an interpretation that is supported by the disturbed dynamical state of many of the host clusters. This hypothesis implies that extreme RPS might occur also near the cores of merging poor clusters or even merging groups of galaxies. Finally, we present nine additional `jellyfish" galaxies at z > 0.3 discovered by us, thereby doubling the number of such systems known at intermediate redshift.

  7. PHOTOMETRIC PROPERTIES AND LUMINOSITY FUNCTION OF NEARBY MASSIVE EARLY-TYPE GALAXIES

    SciTech Connect

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

    2013-08-10

    We perform photometric analyses of a bright early-type galaxy sample with 2949 galaxies (M{sub r} < -22.5 mag) in the redshift range of 0.05-0.15, drawn from the Sloan Digital Sky Survey (SDSS) DR7 with morphological classification from Galaxy Zoo 1. We measure the Petrosian and isophotal magnitudes, as well as the corresponding half-light radius for each galaxy. We find that for the brightest galaxies (M{sub r} < -23 mag), our Petrosian magnitudes and isophotal magnitudes to 25 mag arcsec{sup -2} and 1% of the sky brightness are on average 0.16 mag, 0.20 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case, the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. Similarly, the typical half-light radii (r{sub 50}) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright end of the r-band luminosity function is found to decline more slowly than previous works. Our measured luminosity densities at the bright end are more than one order of magnitude higher than those of Blanton et al., and the stellar mass densities at M{sub *} {approx} 5 Multiplication-Sign 10{sup 11} M{sub Sun} and M{sub *} {approx} 10{sup 12} M{sub Sun} are a few tenths and a factor of a few higher than those of Bernardi et al. These results may significantly alleviate the tension in the assembly of massive galaxies between observations and predictions of the hierarchical structure formation model.

  8. The most massive galaxies in clusters are already fully grown at z ∼ 0.5

    NASA Astrophysics Data System (ADS)

    Oldham, L. J.; Houghton, R. C. W.; Davies, Roger L.

    2017-02-01

    By constructing scaling relations for galaxies in the massive cluster MACSJ0717.5 at z = 0.545 and comparing with those of Coma, we model the luminosity evolution of the stellar populations and the structural evolution of the galaxies. We calculate magnitudes, surface brightnesses and effective radii using Hubble Space Telescope (HST)/ACS images and velocity dispersions using Gemini/GMOS spectra, and present a catalogue of our measurements for 17 galaxies. We also generate photometric catalogues for ∼3000 galaxies from the HST imaging. With these, we construct the colour-magnitude relation, the Fundamental Plane, the mass-to-light versus mass relation, the mass-size relation and the mass-velocity dispersion relation for both clusters. We present a new, coherent way of modelling these scaling relations simultaneously using a simple physical model in order to infer the evolution in luminosity, size and velocity dispersion as a function of redshift, and show that the data can be fully accounted for with this model. We find that (a) the evolution in size and velocity dispersion undergone by these galaxies between z ∼ 0.5 and z ∼ 0 is mild, with Re(z) ∼ (1 + z)-0.40 ± 0.32 and σ(z) ∼ (1 + z)0.09 ± 0.27, and (b) the stellar populations are old, ∼10 Gyr, with a ∼3 Gyr dispersion in age, and are consistent with evolving purely passively since z ∼ 0.5 with Δ log M/L_B = -0.55_{-0.07}^{+0.15} z. The implication is that these galaxies formed their stars early and subsequently grew dissipationlessly so as to have their mass already in place by z ∼ 0.5, and suggests a dominant role for dry mergers, which may have accelerated the growth in these high-density cluster environments.

  9. Stellar kinematics in the nucleus of NGC 6240: A massive galaxy revealed

    NASA Technical Reports Server (NTRS)

    Lester, Dan F.; Gaffney, Niall I.

    1994-01-01

    We have used the 2.3 micron bandhead of CO to measure the kinematics of the red stellar population in the nucleus of the luminous galaxy NGC 6240, the near-infrared spectrum of which is dominated by lines of shocked gas. With this manifest evidence for dissipative effects in the gas, it is such stellar velocity dispersion that is most unambiguously indicative of gravitational potential. We find a nuclear velocity dispersion sigma = 350 km/sec which is considerably larger than that seen in any gaseous component of this galaxy. At least one partner in this merger must therefore have been very massive, with M(sub B) approximately -23. In view of conventional wisdom that the high luminosity of NGC 6240 derives from star formation, it is suprising that we find M/L to be of order unity. While there seems to be little question that star formation is taking place in this interacting system, this high M/L calls into question the importance of star formation in the luminosity budget of the galaxy. In particular, it seems likely that the red starlight in NGC 6240 is produced by giants rather than a population of young red supergiants. This brings into question the (now reflexive) association of relatively deep CO bands in galaxies (which are conspicuously strong in NGC 6240) with recent star formation.

  10. Super Massive Black Holes in Disk Galaxies: HST/STIS Observations for 3 new Objects

    NASA Astrophysics Data System (ADS)

    Coccato, L.; Sarzi, M.; Corsini, E. M.; Pizzella, A.; Bertola, F.

    We present long-slit HST/STIS measurements of the ionized-gas kinematics in the nucleus of three disk galaxies, namely NGC 2179, NGC 4343, NGC 4435. The sample galaxies have been selected on the basis of their ground-based spectroscopy, for displaying a strong central velocity gradient for the ionized gas, which is consistent with the presence of a circumnuclear Keplerian disk (CNKD, Bertola et al. 1998; Funes et al. 2002) rotating around a super massive black hole (SMBH). For each target galaxy we obtained the Hα and [NII] 6583A kinematics along the major axis and two 0.25'' parallel offset positions. Out of three objects only NGC 4435 turned out to have a disk of ionized gas in regular motion and a regular dust-lane morphology. Preliminary modeling indicates a SMBH mass (MBH) one order of magnitude lower than the one expected from the MBH - αc relation for galaxies (Ferrarese & Merritt 2000; Gebhardt et al. 2000).

  11. The MASSIVE Survey. VI. The Spatial Distribution and Kinematics of Warm Ionized Gas in the Most Massive Local Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Pandya, Viraj; Greene, Jenny E.; Ma, Chung-Pei; Veale, Melanie; Ene, Irina; Davis, Timothy A.; Blakeslee, John P.; Goulding, Andy D.; McConnell, Nicholas J.; Nyland, Kristina; Thomas, Jens

    2017-03-01

    We present the first systematic investigation of the existence, spatial distribution, and kinematics of warm ionized gas as traced by the [O ii] 3727 Å emission line in 74 of the most massive galaxies in the local universe. All of our galaxies have deep integral-field spectroscopy from the volume- and magnitude-limited MASSIVE survey of early-type galaxies with stellar mass {log}({M}* /{M}ȯ )> 11.5 (M K < ‑25.3 mag) and distance D < 108 Mpc. Of the 74 galaxies in our sample, we detect warm ionized gas in 28, which yields a global detection fraction of 38 ± 6% down to a typical [O ii] equivalent width limit of 2 Å. MASSIVE fast rotators are more likely to have gas than MASSIVE slow rotators with detection fractions of 80 ± 10% and 28 ± 6%, respectively. The spatial extents span a wide range of radii (0.6–18.2 kpc; 0.1–4R e ), and the gas morphologies are diverse, with 17/28 ≈ 61 ± 9% being centrally concentrated, 8/28 ≈ 29 ± 9% exhibiting clear rotation out to several kiloparsecs, and 3/28 ≈ 11 ± 6% being extended but patchy. Three out of four fast rotators show kinematic alignment between the stars and gas, whereas the two slow rotators with robust kinematic measurements available exhibit kinematic misalignment. Our inferred warm ionized gas masses are roughly ∼105 M ⊙. The emission line ratios and radial equivalent width profiles are generally consistent with excitation of the gas by the old underlying stellar population. We explore different gas origin scenarios for MASSIVE galaxies and find that a variety of physical processes are likely at play, including internal gas recycling, cooling out of the hot gaseous halo, and gas acquired via mergers.

  12. GALAXY EVOLUTION. An over-massive black hole in a typical star-forming galaxy, 2 billion years after the Big Bang.

    PubMed

    Trakhtenbrot, Benny; Urry, C Megan; Civano, Francesca; Rosario, David J; Elvis, Martin; Schawinski, Kevin; Suh, Hyewon; Bongiorno, Angela; Simmons, Brooke D

    2015-07-10

    Supermassive black holes (SMBHs) and their host galaxies are generally thought to coevolve, so that the SMBH achieves up to about 0.2 to 0.5% of the host galaxy mass in the present day. The radiation emitted from the growing SMBH is expected to affect star formation throughout the host galaxy. The relevance of this scenario at early cosmic epochs is not yet established. We present spectroscopic observations of a galaxy at redshift z = 3.328, which hosts an actively accreting, extremely massive BH, in its final stages of growth. The SMBH mass is roughly one-tenth the mass of the entire host galaxy, suggesting that it has grown much more efficiently than the host, contrary to models of synchronized coevolution. The host galaxy is forming stars at an intense rate, despite the presence of a SMBH-driven gas outflow.

  13. The coevolution of supermassive black holes and massive galaxies at high redshift

    SciTech Connect

    Lapi, A.; Raimundo, S.; Aversa, R.; Cai, Z.-Y.; Celotti, A.; De Zotti, G.; Danese, L.; Negrello, M.

    2014-02-20

    We exploit the recent, wide samples of far-infrared (FIR) selected galaxies followed up in X-rays and of X-ray/optically selected active galactic nuclei (AGNs) followed up in the FIR band, along with the classic data on AGNs and stellar luminosity functions at high redshift z ≳ 1.5, to probe different stages in the coevolution of supermassive black holes (BHs) and host galaxies. The results of our analysis indicate the following scenario: (1) the star formation in the host galaxy proceeds within a heavily dust-enshrouded medium at an almost constant rate over a timescale ≲ 0.5-1 Gyr and then abruptly declines due to quasar feedback, over the same timescale; (2) part of the interstellar medium loses angular momentum, reaches the circum-nuclear regions at a rate proportional to the star formation, and is temporarily stored in a massive reservoir/proto-torus wherefrom it can be promptly accreted; (3) the BH grows by accretion in a self-regulated regime with radiative power that can slightly exceed the Eddington limit L/L {sub Edd} ≲ 4, particularly at the highest redshifts; (4) for massive BHs, the ensuing energy feedback at its maximum exceeds the stellar one and removes the interstellar gas, thus stopping the star formation and the fueling of the reservoir; (5) afterward, if the latter has retained enough gas, a phase of supply-limited accretion follows, exponentially declining with a timescale of about two e-folding times. We also discuss how the detailed properties and the specific evolution of the reservoir can be investigated via coordinated, high-resolution observations of star-forming, strongly lensed galaxies in the (sub-)mm band with ALMA and in the X-ray band with Chandra and the next-generation X-ray instruments.

  14. TIGHT CORRELATIONS BETWEEN MASSIVE GALAXY STRUCTURAL PROPERTIES AND DYNAMICS: THE MASS FUNDAMENTAL PLANE WAS IN PLACE BY z ∼ 2

    SciTech Connect

    Bezanson, Rachel; Van Dokkum, Pieter G.; Leja, Joel; Van de Sande, Jesse; Franx, Marijn; Kriek, Mariska

    2013-12-20

    The fundamental plane (FP) is an empirical relation between the size, surface brightness, and velocity dispersion of early-type galaxies. This relation has been studied extensively for early-type galaxies in the local universe to constrain galaxy formation mechanisms. The evolution of the zero point of this plane has been extended to high redshifts to study the luminosity evolution of massive galaxies, under the assumption of structural homology. In this work, we assess this assumption by replacing surface brightness with stellar mass density and present the evolution of the ''mass FP'' for massive, quiescent galaxies since z ∼ 2. By accounting for stellar populations, we thereby isolate and trace structural and dynamical evolution. Despite the observed dramatic evolution in the sizes and morphologies of massive galaxies since z ∼ 3, we find that quiescent galaxies lie on the mass FP out to z ∼ 2. In contrast with ∼1.4 dex evolution in the luminosity FP, average residuals from the z ∼ 0 mass FP are less than ∼0.15 dex since z ∼ 2. Assuming the Hyde and Bernardi mass FP slope, we find that this minimal offset scales as (1 + z){sup –0.095} {sup ±} {sup 0.043}. This result lends credence to previous studies that derived luminosity evolution from the FP. Therefore, despite their compact sizes and suggestions that massive galaxies are more disk-like at z ∼ 2, the relationship between their dynamics and structural properties are consistent with local early-type galaxies. Finally, we find no strong evidence for a tilt of the mass FP relative to the virial plane, but emphasize the need for full models including selection biases to fully investigate this issue.

  15. Herschel-ATLAS Galaxy Counts and High-redshift Luminosity Functions: The Formation of Massive Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Lapi, A.; González-Nuevo, J.; Fan, L.; Bressan, A.; De Zotti, G.; Danese, L.; Negrello, M.; Dunne, L.; Eales, S.; Maddox, S.; Auld, R.; Baes, M.; Bonfield, D. G.; Buttiglione, S.; Cava, A.; Clements, D. L.; Cooray, A.; Dariush, A.; Dye, S.; Fritz, J.; Herranz, D.; Hopwood, R.; Ibar, E.; Ivison, R.; Jarvis, M. J.; Kaviraj, S.; López-Caniego, M.; Massardi, M.; Michałowski, M. J.; Pascale, E.; Pohlen, M.; Rigby, E.; Rodighiero, G.; Serjeant, S.; Smith, D. J. B.; Temi, P.; Wardlow, J.; van der Werf, P.

    2011-11-01

    Exploiting the Herschel Astrophysical Terahertz Large Area Survey Science Demonstration Phase survey data, we have determined the luminosity functions (LFs) at rest-frame wavelengths of 100 and 250 μm and at several redshifts z >~ 1, for bright submillimeter galaxies with star formation rates (SFRs) >~ 100 M ⊙ yr-1. We find that the evolution of the comoving LF is strong up to z ≈ 2.5, and slows down at higher redshifts. From the LFs and the information on halo masses inferred from clustering analysis, we derived an average relation between SFR and halo mass (and its scatter). We also infer that the timescale of the main episode of dust-enshrouded star formation in massive halos (M H >~ 3 × 1012 M ⊙) amounts to ~7 × 108 yr. Given the SFRs, which are in the range of 102-103 M ⊙ yr-1, this timescale implies final stellar masses of the order of 1011-1012 M ⊙. The corresponding stellar mass function matches the observed mass function of passively evolving galaxies at z >~ 1. The comparison of the statistics for submillimeter and UV-selected galaxies suggests that the dust-free, UV bright phase is >~ 102 times shorter than the submillimeter bright phase, implying that the dust must form soon after the onset of star formation. Using a single reference spectral energy distribution (SED; the one of the z ≈ 2.3 galaxy SMM J2135-0102), our simple physical model is able to reproduce not only the LFs at different redshifts >1 but also the counts at wavelengths ranging from 250 μm to ≈1 mm. Owing to the steepness of the counts and their relatively broad frequency range, this result suggests that the dispersion of submillimeter SEDs of z > 1 galaxies around the reference one is rather small. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  16. Galactic models with massive coronae. V. The spiral SAB galaxy M 81

    NASA Astrophysics Data System (ADS)

    Tenjes, P.; Haud, U.; Einasto, J.

    1998-07-01

    Stellar populations in spiral galaxy M 81 are studied by using modelling. The galaxy is assumed to be stationary and consisting of a superposition of several subsystems. Each subsystem corresponds to a certain stellar/gas/dark matter population with a certain density distribution, chemical composition and kinematical characteristics. We presume that equidensity surfaces of the galactic populations are similar concentric ellipsoids or can be represented as sums of such ellipsoids. The input observational data base consists of surface photometry along the minor and major axis in UBVRI colours, rotation velocities of gas, stellar velocity dispersions, distribution and kinematics of globular clusters, distribution of the young stellar component and gas, kinematics of M 81 satellite galaxies. These data are used to decompose the galaxy into a central nucleus, a metal-rich core and a bulge, a metal-poor halo, an old stellar disk, a young gaseous-stellar disk and a massive dark matter component. Each population is characterized by its ellipticity, radius, mass, luminosity, structure parameter and colour indices. These population parameters are found using the least-squares algorithm. The algorithm minimizes the sum of squares of relative deviations of the model from observations. The values of the parameters were calculated in several steps from a preliminary crude model to the final model. The sensitivity of the population parameters to various observational data is analysed. Particular attention is devoted to the dark matter problem. In the final model the mean mass-to-luminosity ratio of the optically visible parts of the galaxy is found to be M/L_B = 5.4+/- 2.4 M_{sun/Lsun, and the ratio of the total mass to the visible one M_T/M_vis = 44. In the inner regions the best fit with observations is obtained when a central point mass 2.7* 10(8) M_{sun is added to the nucleus.

  17. How a Massive Photon Retards the Universal Expansion Until Galaxies Form

    NASA Astrophysics Data System (ADS)

    Bartlett, David F.; Cumalat, J. P.

    2011-04-01

    Michael Faraday understood magnetism from the patterns of iron filings near bar magnets. He deduced the rule that field lines are in tension. Maxwell's stress tensor adds an additional feature, an isotropic pressure B2/8π . Both Maxwell and Faraday believed that electromagnetic fields are scale-invariant. Expressed in the language of particle physics, they believed that m⊙ = 0. A massive photon adds a scale λo inversely proportional to its mass: λo = h/m⊙ c. For scales larger than λo, the vector potential A dominates the magnetic field B. Lines of A are in negative tension; A supports a negative pressure. Here we will show how this negative pressure retards the expansion of the universe. After the formation of galaxies, matter becomes too hot to handle and the universe coasts. We will also discuss the role of the massive photon in binding clusters of galaxies such as the Coma cluster. 1)G.V. Chibisov, Sov. Phys. Usp 19, 624 (1976).

  18. The Argo simulation - I. Quenching of massive galaxies at high redshift as a result of cosmological starvation

    NASA Astrophysics Data System (ADS)

    Feldmann, Robert; Mayer, Lucio

    2015-01-01

    Observations show a prevalence of high-redshift galaxies with large stellar masses and predominantly passive stellar populations. A variety of processes have been suggested that could reduce the star formation in such galaxies to observed levels, including quasar mode feedback, virial shock heating, or galactic winds driven by stellar feedback. However, the main quenching mechanisms have yet to be identified. Here we study the origin of star formation quenching using Argo, a cosmological, hydrodynamical zoom-in simulation that follows the evolution of a massive galaxy at z ≥ 2. This simulation adopts the same subgrid recipes of the Eris simulations, which have been shown to form realistic disc galaxies, and, in one version, adopts also a mass and spatial resolution identical to Eris. The resulting galaxy has properties consistent with those of observed, massive (M* ˜ 1011 M⊙) galaxies at z ˜ 2 and with abundance matching predictions. Our models do not include active galactic nuclei (AGN) feedback indicating that supermassive black holes likely play a subordinate role in determining masses and sizes of massive galaxies at high-z. The specific star formation rate (sSFR) of the simulated galaxy matches the observed M*-sSFR relation at early times. This period of smooth stellar mass growth comes to a sudden halt at z = 3.5 when the sSFR drops by almost an order of magnitude within a few hundred Myr. The suppression is initiated by a levelling off and a subsequent reduction of the cool gas accretion rate on to the galaxy, and not by feedback processes. This `cosmological starvation' occurs as the parent dark matter halo switches from a fast collapsing mode to a slow accretion mode. Additional mechanisms, such as perhaps radio mode feedback from an AGN, are needed to quench any residual star formation of the galaxy and to maintain a low sSFR until the present time.

  19. THE SIZE-STAR FORMATION RELATION OF MASSIVE GALAXIES AT 1.5 < z < 2.5

    SciTech Connect

    Toft, S.; Franx, M.; Van Dokkum, P.; Foerster Schreiber, N. M.; Labbe, I.; Wuyts, S.; Marchesini, D. E-mail: franx@strw.leidenuniv.n E-mail: forster@mpe.mpg.d E-mail: swuyts@cfa.harvard.ed

    2009-11-01

    We study the relation between size and star formation activity in a complete sample of 225 massive (M{sub *} > 5 x 10{sup 10} M {sub sun}) galaxies at 1.5 < z < 2.5, selected from the FIREWORKS UV-IR catalog of the CDFS. Based on stellar population synthesis model fits to the observed rest-frame UV-NIR spectral energy distributions, and independent MIPS 24 mum observations, 65% of the galaxies are actively forming stars, while 35% are quiescent. Using sizes derived from two-dimensional surface brightness profile fits to high-resolution (FWHM{sub PSF} approx 0.''45) ground-based ISAAC data, we confirm and improve the significance of the relation between star formation activity and compactness found in previous studies, using a large, complete mass-limited sample. At z approx 2, massive quiescent galaxies are significantly smaller than massive star-forming galaxies, and a median factor of 0.34 +- 0.02 smaller than galaxies of similar mass in the local universe. Thirteen percent of the quiescent galaxies are unresolved in the ISAAC data, corresponding to sizes <1 kpc, more than five times smaller than galaxies of similar mass locally. The quiescent galaxies span a Kormendy relation which, compared to the relation for local early types, is shifted to smaller sizes and brighter surface brightnesses and is incompatible with passive evolution. The progenitors of the quiescent galaxies were likely dominated by highly concentrated, intense nuclear starbursts at z approx 3-4, in contrast to star-forming galaxies at z approx 2 which are extended and dominated by distributed star formation.

  20. Dual Stellar Halos in the Standard Elliptical Galaxy M105 and Formation of Massive Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Lee, Myung Gyoon; Jang, In Sung

    2016-05-01

    M105 is a standard elliptical galaxy, located in the Leo I Group. We present photometry of the resolved stars in its inner region at R ≈ 4‧ ≈ 4R eff, obtained from F606W and F814W images in the Hubble Space Telescope archive. We combine this with photometry of the outer region at R ≈ 12‧ ≈ 12R eff from archival imaging data. Color-magnitude diagrams of the resolved stars in the inner region show a prominent red giant branch (RGB) with a large color range, while those for the outer region show better a narrow blue RGB. The metallicity distribution function (MDF) of the RGB stars shows the existence of two distinct subpopulations: a dominant metal-rich population (with a peak at [M/H] ≈ 0.0) and a much weaker metal-poor population (with a peak at [M/H] ≈ -1.1). The radial number density profiles of the metal-rich and metal-poor RGB stars are fit well by a Sérsic law with n = 2.75 ± 0.10 and n = 6.89 ± 0.94, and by a single power law (σ ∝ R -3.8 and σ ∝ R -2.6), respectively. The MDFs of the inner and outer regions can be described well by accretion gas models of chemical evolution with two components. These provide strong evidence that there are two distinct stellar halos in this galaxy, blue metal-poor and red metal-rich halos, consistent with the results based on globular cluster systems in bright early-type galaxies (ETGs). We discuss the implications of these results with regard to the formation of massive ETGs in the dual halo mode formation scenario.

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

    SciTech Connect

    Park, KwangHo; Khandai, Nishikanta; Matteo, Tiziana Di; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M.; Feng, Yu

    2015-09-18

    We examine the luminosity function (LF) of [OII] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at 0.06 ≤ z ≤ 3.0 using the [OII] emission line luminosity L([OII]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [OII] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([OII]) = 1043.0 erg s–1 while the low redshifts (z ≤ 0.3) show an excess in the prediction of bright [OII] galaxies, but still displaying a good match with observations below L([OII]) = 1041.6 erg s–1. Based on the validity in reproducing the properties of [OII] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [OII] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from –3 to –2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)–1 at z ≤ 2 while the faint end evolves as ~3(z + 1)–1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [OIII] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. As a result, we show that the auto-correlation function of [OII] and [OIII] emitting galaxies shows a rapid evolution from z = 2 to 1.

  2. Raining on black holes and massive galaxies: the top-down multiphase condensation model

    NASA Astrophysics Data System (ADS)

    Gaspari, M.; Temi, P.; Brighenti, F.

    2017-04-01

    The plasma haloes filling massive galaxies, groups and clusters are shaped by active galactic nucleus (AGN) heating and subsonic turbulence (σv ∼ 150 km s-1), as probed by Hitomi. Novel 3D high-resolution simulations show the soft X-ray, keV hot plasma cools rapidly via radiative emission at the high-density interface of the turbulent eddies, stimulating a top-down condensation cascade of warm 104 K filaments. The kpc-scale ionized (optical/ultraviolet) filaments form a skin enveloping the neutral filaments (optical/infrared/21 cm). The peaks of the warm filaments further condense into cold molecular clouds (<50 K; radio) with total mass of several 107 M⊙ and inheriting the turbulent kinematics. In the core, the clouds collide inelastically, mixing angular momentum and leading to Chaotic Cold Accretion (CCA). The black hole accretion rate (BHAR) can be modelled via quasi-spherical viscous accretion, dot{M}_bullet ∝ ν _c, with clump collisional viscosity νc ≡ λc σv and λc ∼ 100 pc. Beyond the core, pressure torques shape the angular momentum transport. In CCA, the BHAR is recurrently boosted up to 2 dex compared with the disc evolution, which arises as turbulence becomes subdominant. With negligible rotation too, compressional heating inhibits the molecular phase. The CCA BHAR distribution is lognormal with pink noise, f-1 power spectrum characteristic of fractal phenomena. Such chaotic fluctuations can explain the rapid luminosity variability of AGN and high-mass X-ray binaries. An improved criterium to trace non-linear condensation is proposed: σv/vcool ≲ 1. The three-phase CCA reproduces key observations of cospatial multiphase gas in massive galaxies, including Chandra X-ray images, SOAR Hα filaments and kinematics, Herschel [C+] emission and ALMA molecular associations. CCA plays important role in AGN feedback and unification, the evolution of BHs, galaxies and clusters.

  3. 'DARK' GRB 080325 IN A DUSTY MASSIVE GALAXY AT z {approx} 2

    SciTech Connect

    Hashimoto, T.; Ohta, K.; Yabe, K.; Niino, Y.; Aoki, K.; Tanaka, I.; Hattori, T.; Minowa, Y.; Noumaru, J.; Kawai, N.; Aoki, W.; Furusawa, H.; Iye, M.; Komiyama, Y.; Kosugi, G.; Mizumoto, Y.; Ogasawara, R.; Kawabata, K. S.; Kobayashi, N.; Nomoto, K.

    2010-08-10

    We present optical and near-infrared observations of Swift GRB 080325 classified as a 'dark gamma-ray burst (GRB)'. Near-infrared observations with Subaru/MOIRCS provided a clear detection of afterglow in the K{sub s} band, although no optical counterpart was reported. The flux ratio of rest-wavelength optical to X-ray bands of the afterglow indicates that the dust extinction along the line of sight to the afterglow is A{sub V} = 2.7-10 mag. This large extinction is probably the major reason for the optical faintness of GRB 080325. The J - K{sub s} color of the host galaxy, (J - K{sub s} = 1.3 in AB magnitude), is significantly redder than those for typical GRB hosts previously identified. In addition to J and K{sub s} bands, optical images in B, R{sub c} , i', and z' bands with Subaru/Suprime-Cam were obtained at about 1 year after the burst, and a photometric redshift of the host is estimated to be z {sub photo} = 1.9. The host luminosity is comparable to L* at z {approx} 2 in contrast to the sub-L* property of typical GRB hosts at lower redshifts. The best-fit stellar population synthesis model for the host shows that the red nature of the host is attributed to a large dust extinction (A{sub V} = 0.8 mag), and that the host galaxy is massive (M* = 7.0 x 10{sup 10} M {sub sun}), which makes it one of the most massive GRB hosts yet identified. By assuming that the mass-metallicity relation for star-forming galaxies at z {approx} 2 is applicable for the GRB host, this large stellar mass suggests the high-metallicity environment around GRB 080325, consistent with inferred large extinction.

  4. Submillimeter evidence for the coeval growth of massive black holes and galaxy bulges.

    PubMed

    Page, M J; Stevens, J A; Mittaz, J P; Carrera, F J

    2001-12-21

    The correlation, found in nearby galaxies, between black hole mass and stellar bulge mass implies that the formation of these two components must be related. Here we report submillimeter photometry of eight x-ray-absorbed active galactic nuclei that have luminosities and redshifts characteristic of the sources that produce the bulk of the accretion luminosity in the universe. The four sources with the highest redshifts are detected at 850 micrometers, with flux densities between 5.9 and 10.1 millijanskies, and hence are ultraluminous infrared galaxies. If the emission is from dust heated by starbursts, then the majority of stars in spheroids were formed at the same time as their central black holes built up most of their mass by accretion. This would account for the observed demography of massive black holes in the local universe. The skewed rate of submillimeter detection with redshift is consistent with a high redshift epoch of star formation in radio-quiet active galactic nuclei, similar to that seen in radio galaxies.

  5. CHANDRA OBSERVATIONS OF GALAXY ZOO MERGERS: FREQUENCY OF BINARY ACTIVE NUCLEI IN MASSIVE MERGERS

    SciTech Connect

    Teng, Stacy H.; Darg, Dan W.; Kaviraj, Sugata; Lintott, Chris J.; Oh, Kyuseok; Cardamone, Carolin N.; Keel, William C.; Simmons, Brooke D.; Treister, Ezequiel

    2012-07-10

    We present the results from a Chandra pilot study of 12 massive galaxy mergers selected from Galaxy Zoo. The sample includes major mergers down to a host galaxy mass of 10{sup 11} M{sub Sun} that already have optical active galactic nucleus (AGN) signatures in at least one of the progenitors. We find that the coincidences of optically selected active nuclei with mildly obscured (N{sub H} {approx}< 1.1 Multiplication-Sign 10{sup 22} cm{sup -2}) X-ray nuclei are relatively common (8/12), but the detections are too faint (<40 counts per nucleus; f{sub 2-10keV} {approx}< 1.2 Multiplication-Sign 10{sup -13} erg s{sup -1} cm{sup -2}) to reliably separate starburst and nuclear activity as the origin of the X-ray emission. Only one merger is found to have confirmed binary X-ray nuclei, though the X-ray emission from its southern nucleus could be due solely to star formation. Thus, the occurrences of binary AGNs in these mergers are rare (0%-8%), unless most merger-induced active nuclei are very heavily obscured or Compton thick.

  6. THE STELLAR HALOS OF MASSIVE ELLIPTICAL GALAXIES. II. DETAILED ABUNDANCE RATIOS AT LARGE RADIUS

    SciTech Connect

    Greene, Jenny E.; Murphy, Jeremy D.; Graves, Genevieve J.; Gunn, James E.; Raskutti, Sudhir; Comerford, Julia M.; Gebhardt, Karl

    2013-10-20

    We study the radial dependence in stellar populations of 33 nearby early-type galaxies with central stellar velocity dispersions σ{sub *} ∼> 150 km s{sup –1}. We measure stellar population properties in composite spectra, and use ratios of these composites to highlight the largest spectral changes as a function of radius. Based on stellar population modeling, the typical star at 2R{sub e} is old (∼10 Gyr), relatively metal-poor ([Fe/H] ≈ –0.5), and α-enhanced ([Mg/Fe] ≈ 0.3). The stars were made rapidly at z ≈ 1.5-2 in shallow potential wells. Declining radial gradients in [C/Fe], which follow [Fe/H], also arise from rapid star formation timescales due to declining carbon yields from low-metallicity massive stars. In contrast, [N/Fe] remains high at large radius. Stars at large radius have different abundance ratio patterns from stars in the center of any present-day galaxy, but are similar to average Milky Way thick disk stars. Our observations are thus consistent with a picture in which the stellar outskirts are built up through minor mergers with disky galaxies whose star formation is truncated early (z ≈ 1.5-2)

  7. Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active Nuclei in Massive Mergers

    NASA Technical Reports Server (NTRS)

    Teng, Stacy H.; Schawinski, Kevin; Urry, C. Megan; Darg, Dan W.; Kaviraj, Sugata; Oh, Kyuseok; Bonning, Erin W.; Cardamone, Carolin N.; Keel, William C.; Lintott, Chris J.; Simmons, Brooke D.; Treister, Ezequiel

    2012-01-01

    We present the results from a Chandra pilot study of 12 massive galaxy mergers selected from Galaxy Zoo. The sample includes major mergers down to a host galaxy mass of 1011 M that already have optical AGN signatures in at least one of the progenitors. We find that the coincidences of optically selected active nuclei with mildly obscured (N(sub H) approx < 1.1 10(exp 22)/sq cm) X-ray nuclei are relatively common (8/12), but the detections are too faint (< 40 counts per nucleus; (sub -10) keV approx < 1.2 10(exp -13) erg/s/sq cm) to reliably separate starburst and nuclear activity as the origin of the X-ray emission. Only one merger is found to have confirmed binary X-ray nuclei, though the X-ray emission from its southern nucleus could be due solely to star formation. Thus, the occurrences of binary AGN in these mergers are rare (0-8%), unless most merger-induced active nuclei are very heavily obscured or Compton thick.

  8. Investigating star formation properties of galaxies in massive clusters with Herschel and ALMA

    NASA Astrophysics Data System (ADS)

    Wu, John F.; Baker, Andrew J.; Aguirre, Paula; Barkats, D.; Halpern, Mark; Hilton, Matt; Hughes, John Patrick; Infante, Leopoldo; Lindner, Robert; Marriage, Tobias; Menanteau, Felipe; Sifon, Cristobal; Weiss, Axel; ACT Collaboration

    2016-01-01

    I will present results from an investigation of star formation properties of galaxies residing in two massive z ~ 1 clusters (including the 'El Gordo' merger) that were initially selected via their Sunyaev-Zeldovich decrements by the Atacama Cosmology Telescope (ACT) southern survey. This study uses new Herschel Space Observatory and Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 2 observations, which provide information about the dust and cold gas content of galaxies in our targeted clusters. We have detected CO (4-3) and [CI] in individual star-forming cluster galaxies, and also measured stacked continuum and spectral line fluxes at long (e.g., far-infrared, submillimeter, and radio) wavelengths. We use these results to explore the relations between star formation and local environment and cluster dynamical state.This work has been supported by (i) an award issued by JPL/Caltech in association with Herschel, which is a European Space Agency Cornerstone Mission with significant participation by NASA, and (ii) the National Science Foundation through award GSSP SOSPA2-018 from the National Radio Astronomy Observatory, which is operated under cooperative agreement by Associated Universities, Inc.

  9. ATCA detections of massive molecular gas reservoirs in dusty, high-z radio galaxies

    NASA Astrophysics Data System (ADS)

    Heywood, I.; Contreras, Y.; Smith, D. J. B.; Cooray, A.; Dunne, L.; Gómez, L.; Ibar, E.; Ivison, R. J.; Jarvis, M. J.; Michałowski, M. J.; Riechers, D. A.; Werf, P. van der

    2017-02-01

    Observations using the 7-mm receiver system on the Australia Telescope Compact Array have revealed large reservoirs of molecular gas in two high-redshift radio galaxies: HATLAS J090426.9+015448 (z = 2.37) and HATLAS J140930.4+003803 (z = 2.04). Optically, the targets are very faint, and spectroscopy classifies them as narrow-line radio galaxies. In addition to harbouring an active galactic nucleus the targets share many characteristics of sub-mm galaxies. Far-infrared data from Herschel-Astrophysical Terahertz Large Area Survey suggest high levels of dust (>109 M⊙) and a correspondingly large amount of obscured star formation (∼1000 M⊙ yr-1). The molecular gas is traced via the J = 1 → 0 transition of 12CO, its luminosity implying total H2 masses of (1.7 ± 0.3) × 1011 and (9.5 ± 2.4) × 1010 (αCO/0.8) M⊙ in HATLAS J090426.9+015448 and HATLAS J140930.4+003803, respectively. Both galaxies exhibit molecular line emission over a broad (∼1000 km s-1) velocity range and feature double-peaked profiles. We interpret this as evidence of either a large rotating disc or an on-going merger. Gas depletion time-scales are ∼100 Myr. The 1.4-GHz radio luminosities of our targets place them close to the break in the luminosity function. As such they represent 'typical' z > 2 radio sources, responsible for the bulk of the energy emitted at radio wavelengths from accretion-powered sources at high redshift, and yet they rank amongst the most massive systems in terms of molecular gas and dust content. We also detect 115-GHz rest-frame continuum emission, indicating a very steep high-radio-frequency spectrum, possibly classifying the targets as compact steep spectrum objects.

  10. A STRONGLY LENSED MASSIVE ULTRACOMPACT QUIESCENT GALAXY AT z {approx} 2.4 IN THE COSMOS/UltraVISTA FIELD

    SciTech Connect

    Muzzin, Adam; Labbe, Ivo; Franx, Marijn; Holt, J.; Szomoru, Daniel; Van de Sande, Jesse; Van Dokkum, Pieter; Brammer, Gabriel; Marchesini, Danilo; Stefanon, Mauro; Buitrago, F.; Dunlop, James; Caputi, K. I.; Fynbo, J. P. U.; Milvang-Jensen, Bo; Le Fevre, Olivier; McCracken, Henry J.

    2012-12-20

    We report the discovery of a massive ultracompact quiescent galaxy that has been strongly lensed into multiple images by a foreground galaxy at z 0.960. This system was serendipitously discovered as a set of extremely K{sub s} -bright high-redshift galaxies with red J - K{sub s} colors using new data from the UltraVISTA YJHK{sub s} near-infrared survey. The system was also previously identified as an optically faint lens/source system using the COSMOS Advanced Camera for Surveys (ACS) imaging by Faure et al. Photometric redshifts for the three brightest images of the source galaxy determined from 27-band photometry place the source at z = 2.4 {+-} 0.1. We provide an updated lens model for the system that is a good fit to the positions and morphologies of the galaxies in the ACS image. The lens model implies that the magnification of the three brightest images is a factor of 4-5. We use the lens model, combined with the K{sub s} -band image, to constrain the size and Sersic profile of the galaxy. The best-fit model is an ultracompact galaxy (R{sub e} = 0.64{sup +0.08}{sub -0.18} kpc, lensing-corrected), with a Sersic profile that is intermediate between a disk and a bulge profile (n 2.2{sup +2.3}{sub -{sub 0.9}}), albeit with considerable uncertainties on the Sersic profile. We present aperture photometry for the source galaxy images that have been corrected for flux contamination from the central lens. The best-fit stellar population model is a massive galaxy (log(M{sub star}/M{sub Sun }) = 10.8{sup +0.1}{sub -0.1}, lensing-corrected) with an age of 1.0{sup +1.0}{sub -0.4} Gyr, moderate dust extinction (A{sub v} = 0.8{sup +0.5}{sub -0.6}), and a low specific star formation rate (log(SSFR) <-11.0 yr{sup -1}). This is typical of massive ''red-and-dead'' galaxies at this redshift and confirms that this source is the first bona fide strongly lensed massive ultracompact quiescent galaxy to be discovered. We conclude with a discussion of the prospects of finding a larger

  11. The MASSIVE Survey. IV. The X-ray Halos of the Most Massive Early-type Galaxies in the Nearby Universe

    NASA Astrophysics Data System (ADS)

    Goulding, Andy D.; Greene, Jenny E.; Ma, Chung-Pei; Veale, Melanie; Bogdan, Akos; Nyland, Kristina; Blakeslee, John P.; McConnell, Nicholas J.; Thomas, Jens

    2016-08-01

    Studies of the physical properties of local elliptical galaxies are shedding new light on galaxy formation. Here we present the hot-gas properties of 33 early-type systems within the MASSIVE galaxy survey that have archival Chandra X-ray observations, and we use these data to derive X-ray luminosities ({L}{{X,gas}}) and plasma temperatures ({T}{{gas}}) for the diffuse gas components. We combine this with the {{ATLAS}}{{3D}} survey to investigate the X-ray-optical properties of a statistically significant sample of early-type galaxies across a wide range of environments. When X-ray measurements are performed consistently in apertures set by the galaxy stellar content, we deduce that all early types (independent of galaxy mass, environment, and rotational support) follow a universal scaling law such that {L}{{X,gas}}\\propto {T}{{gas}}˜ 4.5. We further demonstrate that the scatter in {L}{{X,gas}} around both K-band luminosity (L K ) and the galaxy stellar velocity dispersion ({σ }e) is primarily driven by {T}{{gas}}, with no clear trends with halo mass, radio power, or angular momentum of the stars. It is not trivial to tie the gas origin directly to either stellar mass or galaxy potential. Indeed, our data require a steeper relation between {L}{{X,gas}},{L}K, and {σ }e than predicted by standard mass-loss models. Finally, we find that {T}{{gas}} is set by the galaxy potential inside the optical effective radius. We conclude that within the innermost 10-30 kpc region, early types maintain pressure-supported hot gas, with a minimum {T}{{gas}} set by the virial temperature, but the majority show evidence for additional heating.

  12. Sunyaev - Zel'dovich Effect Imaging of Massive Clusters of Galaxies at Redshift > 0.8

    NASA Technical Reports Server (NTRS)

    Joy, Marshall; LaRoque, Samuel; Grego, Laura; Carlstrom, John E.; Dawson, Kyle; Ebeling, Harald; Holzapfel, William L.; Nagai, Daisuke; Reese, Erik D.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We present Sunyaev-Zel'dovich Effect (SZE) imaging observations of three distant (z greater than 0.8) and highly X-ray luminous clusters of galaxies, C1J1226+33, C1J0152-13 and MS1054-03. Two of the clusters, C1J1226+33 and C1J0152-13, were recently discovered in the WARPS X-ray survey. Their high X-ray luminosity suggests they are massive systems and, if confirmed, would provide strong constraints on the cosmological parameters of structure formation models. Our Sunyaev-Zel'dovich Effect data provide confirmation that they are massive clusters similar to the well studied cluster MS1054-03. Assuming the clusters have the same gas mass fraction derived from SZE measurements of eighteen known massive clusters, we are able to infer their mass and electron temperatures from the SZE data. The derived electron temperatures are 10.0, 8.5, and 10.3 KeV, respectively, and we infer total masses of approximately 2 x 10(circumflex) 14 h(circumflex) -l M - sun within a radius of 65" for all three clusters. For C1J0152-13 and MS1054-03 we find good agreement between our SZE derived temperatures and those derived from X-ray spectroscopic measurements. No X-ray derived temperatures are available for C1J1226+33, and thus the SZE data provide the first confirmation that it is indeed a massive system. The demonstrated ability to determine cluster temperatures and masses from SZE observations without access to X-ray data illustrates the power of using deep SZE surveys to probe the distant universe.

  13. Massive black hole seeds born via direct gas collapse in galaxy mergers: their properties, statistics and environment

    NASA Astrophysics Data System (ADS)

    Bonoli, Silvia; Mayer, Lucio; Callegari, Simone

    2014-01-01

    We study the statistics and cosmic evolution of massive black hole seeds formed during major mergers of gas-rich late-type galaxies. Generalizing the results of the hydrosimulations from Mayer et al., we envision a scenario in which a supermassive star can form at the centre of galaxies that just experienced a major merger owing to a multiscale powerful gas inflow, provided that such galaxies live in haloes with masses above 1011 M⊙, are gas rich and disc dominated, and do not already host a massive black hole. We assume that the ultimate collapse of the supermassive star leads to the rapid formation of a black hole of 105 M⊙ following a quasi-star stage. Using a model for galaxy formation applied to the outputs of the Millennium Simulation, we show that the conditions required for this massive black hole formation route to take place in the concordance Λ cold dark matter model are actually common at high redshift and can be realized even at low redshift. Most major mergers above z ˜ 4 in haloes with mass >1011 M⊙ can lead to the formation of a massive seed and, at z ˜ 2, the fraction of favourable mergers decreases to about half. Interestingly, we find that even in the local universe a fraction (˜20 per cent) of major mergers in massive haloes still satisfies the conditions for our massive black hole formation route. Those late events take place in galaxies with a markedly low clustering amplitude, that have lived in isolation for most of their life and that are experiencing a major merger for the first time. We predict that massive black hole seeds from galaxy mergers can dominate the massive end of the mass function at high (z > 4) and intermediate (z ˜ 2) redshifts relative to lighter seeds formed at higher redshift, for example, by the collapse of Pop III stars. Finally, a fraction of these massive seeds could lie, soon after formation, above the MBH-MBulge relation.

  14. THE ORIGIN OF METALS IN THE CIRCUMGALACTIC MEDIUM OF MASSIVE GALAXIES AT z = 3

    SciTech Connect

    Shen Sijing; Madau, Piero; Aguirre, Anthony; Guedes, Javiera; Mayer, Lucio; Wadsley, James

    2012-11-20

    We present a detailed study of the metal-enriched circumgalactic medium (CGM) of a massive galaxy at z = 3 using results from 'ErisMC', a new cosmological hydrodynamic 'zoom-in' simulation of a disk galaxy with mass comparable to the Milky Way. The reference run adopts a blast wave scheme for supernova feedback that generates galactic outflows without explicit wind particles, a star formation recipe based on a high gas density threshold and high-temperature metal cooling. ErisMC's main progenitor at z = 3 resembles a 'Lyman break' galaxy of total mass M {sub vir} = 2.4 Multiplication-Sign 10{sup 11} M {sub Sun }, virial radius R {sub vir} = 48 kpc, and star formation rate 18 M {sub Sun} yr{sup -1}, and its metal-enriched CGM extends as far as 200 (physical) kpc from its center. Approximately 41%, 9%, and 50% of all gas-phase metals at z = 3 are locked in a hot (T > 3 Multiplication-Sign 10{sup 5} K), warm (3 Multiplication-Sign 10{sup 5} K > T > 3 Multiplication-Sign 10{sup 4} K), and cold (T < 3 Multiplication-Sign 10{sup 4} K) medium, respectively. We identify three sources of heavy elements: (1) the main host, responsible for 60% of all the metals found within 3 R {sub vir}; (2) its satellite progenitors, which shed their metals before and during infall, and are responsible for 28% of all the metals within 3 R {sub vir}, and for only 5% of those beyond 3 R {sub vir}; and (3) nearby dwarfs, which give origin to 12% of all the metals within 3 R {sub vir} and 95% of those beyond 3 R {sub vir}. Late (z < 5) galactic 'superwinds'-the result of recent star formation in ErisMC-account for only 9% of all the metals observed beyond 2 R {sub vir}, the bulk having been released at redshifts 5 {approx}< z {approx}< 8 by early star formation and outflows. In the CGM, lower overdensities are typically enriched by 'older', colder metals. Heavy elements are accreted onto ErisMC along filaments via low-metallicity cold inflows and are ejected hot via galactic outflows at a few

  15. THE DETECTION OF THE LARGE-SCALE ALIGNMENT OF MASSIVE GALAXIES AT z {approx} 0.6

    SciTech Connect

    Li Cheng; Jing, Y. P.; Faltenbacher, A.; Wang Jie

    2013-06-10

    We report on the detection of the alignment between galaxies and large-scale structure at z {approx} 0.6 based on the CMASS galaxy sample from the Baryon Oscillation Spectroscopy Survey Data Release 9. We use two statistics to quantify the alignment signal: (1) the alignment two-point correlation function that probes the dependence of galaxy clustering at a given separation in redshift space on the projected angle ({theta}{sub p}) between the orientation of galaxies and the line connecting to other galaxies, and (2) the cos (2{theta})-statistic that estimates the average of cos (2{theta}{sub p}) for all correlated pairs at a given separation s. We find a significant alignment signal out to about 70 h {sup -1} Mpc in both statistics. Applications of the same statistics to dark matter halos of mass above 10{sup 12} h {sup -1} M{sub Sun} in a large cosmological simulation show scale-dependent alignment signals similar to the observation, but with higher amplitudes at all scales probed. We show that this discrepancy may be partially explained by a misalignment angle between central galaxies and their host halos, though detailed modeling is needed in order to better understand the link between the orientations of galaxies and host halos. In addition, we find systematic trends of the alignment statistics with the stellar mass of the CMASS galaxies, in the sense that more massive galaxies are more strongly aligned with the large-scale structure.

  16. HIGH-VELOCITY OUTFLOWS WITHOUT AGN FEEDBACK: EDDINGTON-LIMITED STAR FORMATION IN COMPACT MASSIVE GALAXIES

    SciTech Connect

    Diamond-Stanic, Aleksandar M.; Moustakas, John; Coil, Alison L.; Tremonti, Christy A.; Sell, Paul H.; Hickox, Ryan C.; Robaina, Aday R.; Rudnick, Gregory H.

    2012-08-20

    We present the discovery of compact, obscured star formation in galaxies at z {approx} 0.6 that exhibit {approx}> 1000 km s{sup -1} outflows. Using optical morphologies from the Hubble Space Telescope and infrared photometry from the Wide-field Infrared Survey Explorer, we estimate star formation rate (SFR) surface densities that approach {Sigma}{sub SFR} Almost-Equal-To 3000 M{sub Sun} yr{sup -1} kpc{sup -2}, comparable to the Eddington limit from radiation pressure on dust grains. We argue that feedback associated with a compact starburst in the form of radiation pressure from massive stars and ram pressure from supernovae and stellar winds is sufficient to produce the high-velocity outflows we observe, without the need to invoke feedback from an active galactic nucleus.

  17. Star Formation at Low Rates: How a Lack of Massive Stars Impacts the Evolution of Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Hensler, Gerhard

    2017-01-01

    In recent years dedicated observations have uncovered star formation at extremely low rates in dwarf galaxies, tidal tails, ram-pressure stripped gas clouds, and the outskirts of galactic disks. At the same time, numerical simulations of galaxy evolution have advanced to higher spatial and mass resolutions, but have yet to account for the underfilling of the uppermost mass bins of stellar initial mass function (IMF) at low star-formation rates. In such situations, simulations may simply scale down the IMF, without realizing that this unrealistically results infractions of massive stars, along with fractions of massive star feedback energy (e.g., radiation and SNII explosions). Not properlyaccounting for such parameters has consequences for the self-regulation of star formation, the energetics of galaxies, as well as for the evolution of chemical abundances.Here we present numerical simulations of dwarf galaxies with low star-formation rates allowing for two extreme cases of the IMF: a "filled" case with fractional massive stars vs. a truncated IMF, at which the IMF is built bottom-up until the gas reservoir allows the formation of a last single star at an uppermost mass. The aim of the study is to demonstrate the different effects on galaxy evolution with respect to self-regulation, feedback, and chemistry. The case of a stochastic sampled IMF is situated somewhere in between these extremes.

  18. Core-collapse supernova progenitor constraints using the spatial distributions of massive stars in local galaxies

    NASA Astrophysics Data System (ADS)

    Kangas, T.; Portinari, L.; Mattila, S.; Fraser, M.; Kankare, E.; Izzard, R. G.; James, P.; González-Fernández, C.; Maund, J. R.; Thompson, A.

    2017-01-01

    We studied the spatial correlations between the Hα emission and different types of massive stars in two local galaxies, the Large Magellanic Cloud (LMC) and Messier 33. We compared these to correlations derived for core-collapse supernovae (CCSNe) in the literature to connect CCSNe of different types with the initial masses of their progenitors and to test the validity of progenitor mass estimates which use the pixel statistics method. We obtained samples of evolved massive stars in both galaxies from catalogues with good spatial coverage and/or completeness, and combined them with coordinates of main-sequence stars in the LMC from the SIMBAD database. We calculated the spatial correlation of stars of different classes and spectral types with Hα emission. We also investigated the effects of distance, noise and positional errors on the pixel statistics method. A higher correlation with Hα emission is found to correspond to a shorter stellar lifespan, and we conclude that the method can be used as an indicator of the ages, and therefore initial masses, of SN progenitors. We find that the spatial distributions of type II-P SNe and red supergiants of appropriate initial mass (≳9 M⊙) are consistent with each other. We also find the distributions of type Ic SNe and WN stars with initial masses ≳20 M⊙ consistent, while supergiants with initial masses around 15 M⊙ are a better match for type IIb and II-L SNe. The type Ib distribution corresponds to the same stellar types as type II-P, which suggests an origin in interacting binaries. On the other hand, we find that luminous blue variable stars show a much stronger correlation with Hα emission than do type IIn SNe.

  19. Star formation in massive Milky Way molecular clouds: Building a bridge to distant galaxies

    NASA Astrophysics Data System (ADS)

    Willis, Sarah Elizabeth

    The Kennicutt-Schmidt relation is an empirical power-law linking the surface density of the star formation rate (SigmaSFR) to the surface density of gas (Sigmagas ) averaged over the observed face of a starforming galaxy Kennicutt (1998). The original presentation used observations of CO to measure gas density and H alpha emission to measure the population of hot, massive young stars (and infer the star formation rate). Observations of Sigma SFR from a census of young stellar objects in nearby molecular clouds in our Galaxy are up to 17 times higher than the extragalactic relation would predict given their Sigmagas. These clouds primarily form low-mass stars that are essentially invisible to star formation rate tracers. A sample of six giant molecular cloud (GMC) complexes with signposts of massive star formation was identified in our galaxy. The regions selected have a range of total luminosity and morphology. Deep ground-based observations in the near-infrared with NEWFIRM and IRAC observations with the Spitzer Space Telescope were used to conduct a census of the young stellar content associated with each of these clouds. The star formation rates from the stellar census in each of these regions was compared with the star formation rates measured by extragalactic star formation rate tracers based on monochromatic mid-infrared luminosities. Far-infrared Herschel observations from 160 through 500 mum were used to determine the column density and temperature in each region. The region NGC 6334 served as a test case to compare the Herschel column density measurements with the measurements for near-infrared extinction. The combination of the column density maps and the stellar census lets us examine SigmaSFR vs. Sigma gas for the massive GMCs. These regions are consistent with the results for the low-mass molecular clouds, indicating Sigma SFR levels that are higher than predicted based on Sigma gas. The overall Sigmagas levels are higher for the massive star forming

  20. Radio AGN signatures in massive quiescent galaxies out to z=1.5

    NASA Astrophysics Data System (ADS)

    Järvelä, Emilia

    2016-08-01

    Detection of gamma-rays from narrow-line Seyfert 1 galaxies (NLS1) by Fermi confirmed the presence of powerful relativistic jets in them, and thus challenged our understanding of active galactic nuclei (AGN). In the current AGN paradigm powerful relativistic jets are produced in massive elliptical galaxies with supermassive black holes. NLS1s differ from them significantly; they harbour lower mass black holes accreting at higher Eddington ratios, have preferably compact radio morphology, reside mostly in spiral galaxies, and were thought to be radio-quiet.Fermi's discovery invokes questions about the AGN evolution; what triggers and maintains the AGN activity, and what are the evolutionary lines of the different populations? It is also necessary to revise the AGN unification schemes to fit in NLS1s. They convolute the whole AGN scenario, but offer us a new look on the jet phenomena and will help us construct a more comprehensive big picture of AGN.Despite their importance, NLS1s are rather poorly studied as a class. For example, some NLS1s seem to be totally radio-silent, but a considerable fraction are radio-loud and thus probably host jets. This, along with other observational evidence, implies that they do not form a homogeneous class. However, it remains unclear what is triggering the radio loudness in some of them, but, for example, the properties of the host galaxy and the large-scale environment might play a role. Also the parent population of NLS1s remains an open question.We used various statistical methods, for example, multiwavelength correlations and principal component analysis to study a large sample of NLS1 sources. We will present the results and discuss the interplay between their properties, such as emission properties, black hole masses, large-scale environments, and their effect on radio loudness. We will also introduce the Metsähovi Radio Observatory NLS1 galaxy observing programme, which is the first one dedicated to systematical observations

  1. Mpc-scale diffuse radio emission in two massive cool-core clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Sommer, Martin W.; Basu, Kaustuv; Intema, Huib; Pacaud, Florian; Bonafede, Annalisa; Babul, Arif; Bertoldi, Frank

    2017-04-01

    Radio haloes are diffuse synchrotron sources on scales of ∼1 Mpc that are found in merging clusters of galaxies, and are believed to be powered by electrons re-accelerated by merger-driven turbulence. We present measurements of extended radio emission on similarly large scales in two clusters of galaxies hosting cool cores: Abell 2390 and Abell 2261. The analysis is based on interferometric imaging with the Karl G. Jansky Very Large Array, Very Large Array and Giant Metrewave Radio Telescope. We present detailed radio images of the targets, subtract the compact emission components and measure the spectral indices for the diffuse components. The radio emission in A2390 extends beyond a known sloshing-like brightness discontinuity, and has a very steep in-band spectral slope at 1.5 GHz that is similar to some known ultrasteep spectrum radio haloes. The diffuse signal in A2261 is more extended than in A2390 but has lower luminosity. X-ray morphological indicators, derived from XMM-Newton X-ray data, place these clusters in the category of relaxed or regular systems, although some asymmetric features that can indicate past minor mergers are seen in the X-ray brightness images. If these two Mpc-scale radio sources are categorized as giant radio haloes, they question the common assumption of radio haloes occurring exclusively in clusters undergoing violent merging activity, in addition to commonly used criteria for distinguishing between radio haloes and minihaloes.

  2. The MassiveBlack-II simulation: The evolution of haloes and galaxies to z ~ 0

    DOE PAGES

    Khandai, Nishikanta; Di Matteo, Tiziana; Croft, Rupert; ...

    2015-04-24

    We investigate the properties and clustering of halos, galaxies and blackholes to z = 0 in the high resolution hydrodynamical simulation MassiveBlack-II (MBII). MBII evolves a ΛCDM cosmology in a cubical comoving volume Vbox = (100Mpc/h)³. It is the highest resolution simulation of this size which includes a self-consistent model for star formation, black hole accretion and associated feedback. We provide a simulation browser web application which enables interactive search and tagging of the halos, subhalos and their properties and publicly release our galaxy catalogs to the scientific community. Our analysis of the halo mass function in MBII reveals thatmore » baryons have strong effects with changes in the halo abundance of 20–35% below the knee of the mass function (Mhalo 1013.2 M⊙ h at z = 0) when compared to dark-matter-only simulations. We provide a fitting function for the halo MF out to redshift z = 11 and discuss its limitations.« less

  3. A massive star origin for an unusual helium-rich supernova in an elliptical galaxy.

    PubMed

    Kawabata, K S; Maeda, K; Nomoto, K; Taubenberger, S; Tanaka, M; Deng, J; Pian, E; Hattori, T; Itagaki, K

    2010-05-20

    The unusual helium-rich (type Ib) supernova SN 2005E is distinguished from all supernovae hitherto observed by its faint and rapidly fading light curve, prominent calcium lines in late-phase spectra and lack of any mark of recent star formation near the supernova location. These properties are claimed to be explained by a helium detonation in a thin surface layer of an accreting white dwarf. Here we report that the observed properties of SN 2005cz, which appeared in an elliptical galaxy, resemble those of SN 2005E. We argue that these properties are best explained by a core-collapse supernova at the low-mass end (8-12 solar masses) of the range of massive stars that explode. Such a low-mass progenitor lost its hydrogen-rich envelope through binary interaction, had very thin oxygen-rich and silicon-rich layers above the collapsing core, and accordingly ejected a very small amount of radioactive (56)Ni and oxygen. Although the host galaxy NGC 4589 is an elliptical, some studies have revealed evidence of recent star-formation activity, consistent with the core-collapse model.

  4. The MassiveBlack-II simulation: The evolution of haloes and galaxies to z ~ 0

    SciTech Connect

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

    2015-04-24

    We investigate the properties and clustering of halos, galaxies and blackholes to z = 0 in the high resolution hydrodynamical simulation MassiveBlack-II (MBII). MBII evolves a ΛCDM cosmology in a cubical comoving volume Vbox = (100Mpc/h)³. It is the highest resolution simulation of this size which includes a self-consistent model for star formation, black hole accretion and associated feedback. We provide a simulation browser web application which enables interactive search and tagging of the halos, subhalos and their properties and publicly release our galaxy catalogs to the scientific community. Our analysis of the halo mass function in MBII reveals that baryons have strong effects with changes in the halo abundance of 20–35% below the knee of the mass function (Mhalo 1013.2 M h at z = 0) when compared to dark-matter-only simulations. We provide a fitting function for the halo MF out to redshift z = 11 and discuss its limitations.

  5. Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active Nuclei in Massive Mergers

    NASA Technical Reports Server (NTRS)

    Teng, Stacy H.; Schwainski, Kevin; Urry, C. Megan; Darg, Dan W.; Kaviraj, Sugata; Oh, Kyuseok; Bonning, Erin W.; Cardamone, Carolin N.; Keel, William C.; Lintott, Chris J.; Simmons, Brooke D.; Treister, Ezequiel

    2012-01-01

    We present the results from a Chandra pilot study of 12 massive mergers selected from Galaxy Zoo. The sample includes major mergers down to a host galaxy mass of 10(sup 11) solar mass that already have optical AGN signatures in at least one of the progenitors. We find that the coincidences of optically selected active nuclei with mildly obscured (N(sub H) less than or approximately 1.1 x 10(exp 22) per square centimeter) X-ray nuclei are relatively common (8/12), but the detections are too faint (less than 40 counts per nucleus; f(sub 2-10 keV) less than or approximately 1.2 x 10(exp -13) ergs per second per square centimeter) to separate starburst and nuclear activity as the origin of the X-ray emission. Only one merger is found to have confirmed binary X-ray nuclei, though the X-ray emission from its southern nucleus could be due solely to star formation. Thus, the occurrences of binary AGN in these mergers are rare (0-8%), unless most merger-induced active nuclei are very heavily obscured or Compton thick.

  6. The Mass, Color, and Structural Evolution of Today’s Massive Galaxies Since z ∼ 5

    NASA Astrophysics Data System (ADS)

    Hill, Allison R.; Muzzin, Adam; Franx, Marijn; Clauwens, Bart; Schreiber, Corentin; Marchesini, Danilo; Stefanon, Mauro; Labbe, Ivo; Brammer, Gabriel; Caputi, Karina; Fynbo, Johan; Milvang-Jensen, Bo; Skelton, Rosalind E.; van Dokkum, Pieter; Whitaker, Katherine E.

    2017-03-01

    In this paper, we use stacking analysis to trace the mass growth, color evolution, and structural evolution of present-day massive galaxies ({log}({M}* /{M}ȯ )=11.5) out to z = 5. We utilize the exceptional depth and area of the latest UltraVISTA data release, combined with the depth and unparalleled seeing of CANDELS to gather a large, mass-selected sample of galaxies in the NIR (rest-frame optical to UV). Progenitors of present-day massive galaxies are identified via an evolving cumulative number density selection, which accounts for the effects of merging to correct for the systematic biases introduced using a fixed cumulative number density selection, and find progenitors grow in stellar mass by ≈ 1.5 {dex} since z = 5. Using stacking, we analyze the structural parameters of the progenitors and find that most of the stellar mass content in the central regions was in place by z∼ 2, and while galaxies continue to assemble mass at all radii, the outskirts experience the largest fractional increase in stellar mass. However, we find evidence of significant stellar mass build-up at r< 3 {kpc} beyond z> 4 probing an era of significant mass assembly in the interiors of present-day massive galaxies. We also compare mass assembly from progenitors in this study to the EAGLE simulation and find qualitatively similar assembly with z at r< 3 {kpc}. We identify z∼ 1.5 as a distinct epoch in the evolution of massive galaxies where progenitors transitioned from growing in mass and size primarily through in situ star formation in disks to a period of efficient growth in r e consistent with the minor merger scenario.

  7. The Evolution of Massive Morphological Spheroid and Disk Galaxies in CANDELS from 11 to 6 Billion Years Ago

    NASA Astrophysics Data System (ADS)

    McIntosh, Daniel H.; CANDELS Collaboration

    2017-01-01

    The premiere HST/WFC3 Treasury program CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey) has produced detailed visual classifications for statistically useful samples of bright (H>24.5mag) galaxies during and after z~2, the epoch of peak galaxy development. By averaging multiple classifications per galaxy that encompass spheroid-only, bulge-dominated, disk-dominated, disk-only, and irregular/peculiar appearances at visible rest-frame wavelengths, we find that 90% of massive (>1e10 Msun) galaxies at 0.62 to mostly Q at later times. Combining morphologies, structural properties, and SF nature, we find clear differences in the histories of spheroid and disk populations that are robust to selections based on visual or Sersic selection, and to either Q/SF divisor. Massive spheroids experience strong number density growth, substantial size growth, and rapid changes in SF fraction suggesting quenching processes that act on <0.5 Gyr timescales. In contrast, the massive disk population undergoes a steady addition of similar-size disks and a mild decline in average sSFR. Our results indicate that active SF in disks appears to slowly build up their inner mass (or bulge), which subsequently quenches these galaxies. Data-theory comparison is needed to better constrain which physical processes drive the transformation and quenching of massive galaxies.

  8. The ALMA Redshift 4 Survey (AR4S). I. The massive end of the z = 4 main sequence of galaxies

    NASA Astrophysics Data System (ADS)

    Schreiber, C.; Pannella, M.; Leiton, R.; Elbaz, D.; Wang, T.; Okumura, K.; Labbé, I.

    2017-03-01

    We introduce the ALMA Redshift 4 Survey (AR4S), a systematic ALMA survey of all the known galaxies with stellar mass (M∗) larger than 5 × 1010M⊙ at 3.5 galaxies observed with ALMA at 890 μm (180 μm rest-frame) with an on-source integration time of 1.3 min per galaxy. We detected 32% of the sample at more than 3σ significance. Using the stacked ALMA and Herschel photometry, we derived an average dust temperature of 40 ± 2 K for the whole sample, and extrapolate the LIR and SFR for all our galaxies based on their ALMA flux. We then used a forward modeling approach to estimate their intrinsic sSFR distribution, deconvolved of measurement errors and selection effects: we find a linear relation between SFR and M∗, with a median sSFR = 2.8 ± 0.8 Gyr and a dispersion around that relation of 0.28 ± 0.13 dex. This latter value is consistent with that measured at lower redshifts, which is proof that the main sequence of star-forming galaxies was already in place at z = 4, at least among massive galaxies. These new constraints on the properties of the main sequence are in good agreement with the latest predictions from numerical simulations, and suggest that the bulk of star formation in galaxies is driven by the same mechanism from z = 4 to the present day, that is, over at least 90% of the cosmic history. We also discuss the consequences of our results on the population of early quiescent galaxies. This paper is part of a series that will employ these new ALMA observations to explore the star formation and dust properties of the massive end of the z = 4 galaxy population.

  9. A spectroscopic sample of massive, quiescent z ∼ 2 galaxies: implications for the evolution of the mass-size relation

    SciTech Connect

    Krogager, J.-K.; Zirm, A. W.; Toft, S.; Man, A.; Brammer, G.

    2014-12-10

    We present deep, near-infrared Hubble Space Telescope/Wide Field Camera 3 grism spectroscopy and imaging for a sample of 14 galaxies at z ≈ 2 selected from a mass-complete photometric catalog in the COSMOS field. By combining the grism observations with photometry in 30 bands, we derive accurate constraints on their redshifts, stellar masses, ages, dust extinction, and formation redshifts. We show that the slope and scatter of the z ∼ 2 mass-size relation of quiescent galaxies is consistent with the local relation, and confirm previous findings that the sizes for a given mass are smaller by a factor of two to three. Finally, we show that the observed evolution of the mass-size relation of quiescent galaxies between z = 2 and 0 can be explained by the quenching of increasingly larger star forming galaxies at a rate dictated by the increase in the number density of quiescent galaxies with decreasing redshift. However, we find that the scatter in the mass-size relation should increase in the quenching-driven scenario in contrast to what is seen in the data. This suggests that merging is not needed to explain the evolution of the median mass-size relation of massive galaxies, but may still be required to tighten its scatter, and explain the size growth of individual z = 2 galaxies quiescent galaxies.

  10. The redshift evolution of massive galaxy clusters in the MACSIS simulations

    NASA Astrophysics Data System (ADS)

    Barnes, David J.; Kay, Scott T.; Henson, Monique A.; McCarthy, Ian G.; Schaye, Joop; Jenkins, Adrian

    2017-02-01

    We present the MAssive ClusterS and Intercluster Structures (MACSIS) project, a suite of 390 clusters simulated with baryonic physics that yields realistic massive galaxy clusters capable of matching a wide range of observed properties. MACSIS extends the recent BAryons and HAloes of MAssive Systems simulation to higher masses, enabling robust predictions for the redshift evolution of cluster properties and an assessment of the effect of selecting only the hottest systems. We study the observable-mass scaling relations and the X-ray luminosity-temperature relation over the complete observed cluster mass range. As expected, we find that the slope of these scaling relations and the evolution of their normalization with redshift depart significantly from the self-similar predictions. However, for a sample of hot clusters with core-excised temperatures kBT ≥ 5 keV, the normalization and the slope of the observable-mass relations and their evolution are significantly closer to self-similar. The exception is the temperature-mass relation, for which the increased importance of non-thermal pressure support and biased X-ray temperatures leads to a greater departure from self-similarity in the hottest systems. As a consequence, these also affect the slope and evolution of the normalization in the luminosity-temperature relation. The median hot gas profiles show good agreement with observational data at z = 0 and z = 1, with their evolution again departing significantly from the self-similar prediction. However, selecting a hot sample of clusters yields profiles that evolve significantly closer to the self-similar prediction. In conclusion, our results show that understanding the selection function is vital for robust calibration of cluster properties with mass and redshift.

  11. The impact of baryons on massive galaxy clusters: halo structure and cluster mass estimates

    NASA Astrophysics Data System (ADS)

    Henson, Monique A.; Barnes, David J.; Kay, Scott T.; McCarthy, Ian G.; Schaye, Joop

    2017-03-01

    We use the BAHAMAS (BAryons and HAloes of MAssive Systems) and MACSIS (MAssive ClusterS and Intercluster Structures) hydrodynamic simulations to quantify the impact of baryons on the mass distribution and dynamics of massive galaxy clusters, as well as the bias in X-ray and weak lensing mass estimates. These simulations use the subgrid physics models calibrated in the BAHAMAS project, which include feedback from both supernovae and active galactic nuclei. They form a cluster population covering almost two orders of magnitude in mass, with more than 3500 clusters with masses greater than 1014 M⊙ at z = 0. We start by characterizing the clusters in terms of their spin, shape and density profile, before considering the bias in both weak lensing and hydrostatic mass estimates. Whilst including baryonic effects leads to more spherical, centrally concentrated clusters, the median weak lensing mass bias is unaffected by the presence of baryons. In both the dark matter only and hydrodynamic simulations, the weak lensing measurements underestimate cluster masses by ≈10 per cent for clusters with M200 ≤ 1015 M⊙ and this bias tends to zero at higher masses. We also consider the hydrostatic bias when using both the true density and temperature profiles, and those derived from X-ray spectroscopy. When using spectroscopic temperatures and densities, the hydrostatic bias decreases as a function of mass, leading to a bias of ≈40 per cent for clusters with M500 ≥ 1015 M⊙. This is due to the presence of cooler gas in the cluster outskirts. Using mass weighted temperatures and the true density profile reduces this bias to 5-15 per cent.

  12. Self-similar hierarchical energetics in the ICM of massive galaxy clusters

    NASA Astrophysics Data System (ADS)

    Miniati, Francesco; Beresnyak, Andrey

    Massive galaxy clusters (GC) are filled with a hot, turbulent and magnetised intra-cluster medium (ICM). They are still forming under the action of gravitational instability, which drives supersonic mass accretion flows. These partially dissipate into heat through a complex network of large scale shocks, and partly excite giant turbulent eddies and cascade. Turbulence dissipation not only contributes to heating of the ICM but also amplifies magnetic energy by way of dynamo action. The pattern of gravitational energy turning into kinetic, thermal, turbulent and magnetic is a fundamental feature of GC hydrodynamics but quantitative modelling has remained a challenge. In this contribution we present results from a recent high resolution, fully cosmological numerical simulation of a massive Coma-like galaxy cluster in which the time dependent turbulent motions of the ICM are resolved (Miniati 2014) and their statistical properties are quantified for the first time (Miniati 2015, Beresnyak & Miniati 2015). We combine these results with independent state-of-the art numerical simulations of MHD turbulence (Beresnyak 2012), which shows that in the nonlinear regime of turbulent dynamo (for magnetic Prandtl numbers>~ 1) the growth rate of the magnetic energy corresponds to a fraction CE ~= 4 - 5 × 10-2 of the turbulent dissipation rate. We thus determine without adjustable parameters the thermal, turbulent and magnetic history of giant GC (Miniati & Beresnyak 2015). We find that the energy components of the ICM are ordered according to a permanent hierarchy, in which the sonic Mach number at the turbulent injection scale is of order unity, the beta of the plasma of order forty and the ratio of turbulent injection scale to Alfvén scale is of order one hundred. These dimensionless numbers remain virtually unaltered throughout the cluster's history, despite evolution of each individual component and the drive towards equipartition of the turbulent dynamo, thus revealing a new

  13. H-Band dropouts in the deepest CANDELS field. A new population of bright massive galaxies at z >3

    NASA Astrophysics Data System (ADS)

    Alcalde Pampliega, B.; Pérez-González, P. G.; Domínguez Sánchez, H.; Esquej, P.; Eliche-Moral, M. C.; Barro, G.

    2015-05-01

    The recent increase in depth, spatial and wavelength coverage of extragalactic surveys has improved dramatically our understanding of galaxy formation and evolution and is revealing a new population of galaxies at high redshift. That is consistent with a downsizing (Cowie, L. L., Songaila, A., Hu, E. M., & Cohen, J. G. 1996, AJ, 112, 839; Heavens, A., Panter, B., Jiménez, R., & Dunlop, J. 2004, Nature, 428, 625; Juneau, S., et al. 2005, ApJ, 619, L135; Bauer, A. E., Drory, N., Hill, G. J., & Feulner, G. 2005, ApJ, 621, L89; Pérez-González et al. 2008, ApJ, 675, 234) scenario, which implies that the most massive galaxies formed early in the history of the universe and evolved quickly. Red color criteria and the analysis of deep mid-IR, has been proven to very useful to identify high-z extremely red galaxies as shown in (Caputi, K. et al. 2012, ApJ, 750, L20 and Huang, J.-S., Zheng, X. Z., Rigopoulou, D. et al., 2011, ApJ, 742, L13). We present our analysis of the deepest near-infrared (F160W/H-band from CANDELS) and mid-infrared (IRAC from GOODS) data taken by HST and Spitzer (in the GOODS fields) to select sources only detected by IRAC and with no CANDELS counterpart (i.e., H>27, [3.6]≤25). These H-Band dropouts constitute a previously unknown population of dust-enshrouded and/or quiescent massive red galaxies at z>3. Using the wealth of data available in the GOODS field, especially the SHARDS data, we characterize the properties of this population of red galaxies and discuss on its relevance for previous estimations of the stellar mass function at z=3-5, and the evolution of massive galaxies in the early Universe.

  14. Order statistics applied to the most massive and most distant galaxy clusters

    NASA Astrophysics Data System (ADS)

    Waizmann, J.-C.; Ettori, S.; Bartelmann, M.

    2013-06-01

    In this work, we present an analytic framework for calculating the individual and joint distributions of the nth most massive or nth highest redshift galaxy cluster for a given survey characteristic allowing us to formulate Λ cold dark matter (ΛCDM) exclusion criteria. We show that the cumulative distribution functions steepen with increasing order, giving them a higher constraining power with respect to the extreme value statistics. Additionally, we find that the order statistics in mass (being dominated by clusters at lower redshifts) is sensitive to the matter density and the normalization of the matter fluctuations, whereas the order statistics in redshift is particularly sensitive to the geometric evolution of the Universe. For a fixed cosmology, both order statistics are efficient probes of the functional shape of the mass function at the high-mass end. To allow a quick assessment of both order statistics, we provide fits as a function of the survey area that allow percentile estimation with an accuracy better than 2 per cent. Furthermore, we discuss the joint distributions in the two-dimensional case and find that for the combination of the largest and the second largest observation, it is most likely to find them to be realized with similar values with a broadly peaked distribution. When combining the largest observation with higher orders, it is more likely to find a larger gap between the observations and when combining higher orders in general, the joint probability density function peaks more strongly. Having introduced the theory, we apply the order statistical analysis to the Southpole Telescope (SPT) massive cluster sample and metacatalogue of X-ray detected clusters of galaxies catalogue and find that the 10 most massive clusters in the sample are consistent with ΛCDM and the Tinker mass function. For the order statistics in redshift, we find a discrepancy between the data and the theoretical distributions, which could in principle indicate a

  15. Why do the HIghMass Galaxies Have so Much Gas?: Studying Massive, Gas-Rich Galaxies at z~0 with Resolved HI and H2

    NASA Astrophysics Data System (ADS)

    Hallenbeck, Gregory L.; HIghMass Team

    2016-01-01

    In the standard ΛCDM cosmology, galaxies form via mergers of many smaller dark matter halos. Because mergers drive star formation, the most massive galaxies should also be the ones which have been the most efficient at converting their gas reservoirs into stars. This trend is seen observationally: in general, as stellar mass increases, gas fraction (GF = MHI/M*) decreases. Galaxies which have large reservoirs of atomic hydrogen (HI) are thus expected to be extremely rare, which was seemingly supported by earlier blind HI surveys.In seeming contradiction, ALFALFA, the Arecibo Legacy Fast ALFA Survey has observed a sample of 34 galaxies which are both massive (MHI>1010 M⊙) and have unusually high gas fractions (all ≥ 0.3; half are > 1). We call this sample HighMass. Unlike other extremely HI-massive samples, such galaxies are neither low surface brightness galaxies nor are they simply "scaled up" spirals. Could this gas be recently acquired, either from accreting small companions or directly from the cosmic web? Or is it primordial, and has been kept from forming stars, possibly because of an unusually high dark matter halo spin parameter?We present resolved HI, H2, and star formation properties of three of these HIghMass galaxies, and compare them with two HIghMass galaxies previously discussed in Hallenbeck et al. (2014). One of these galaxies, UGC 6168, appears in the process of transitioning from a quiescent to star-forming phase, as indicated by its bar and potential non-circular flows. A second, UGC 7899, has a clear warp, which could be evidence of recently accreted gas—but the presence of a warp is far from conclusive evidence. Both have moderately high dark matter halo spin parameters (λ' = 0.09), similar to the previously studied UGC 9037. The third, NGC 5230, looks undisturbed both optically and in its radio emission, but is in a group full of extragalactic gas. A neighboring galaxy has been significantly disrupted, and NGC 5230 may be in the

  16. The Trace of the Assembly of Massive E-S0 Galaxies at 0.8Galaxy Number Counts

    NASA Astrophysics Data System (ADS)

    Prieto, M.; Eliche-Moral, M. C.

    2016-10-01

    K-band galaxy number counts (GNCs) exhibit a slope change at K˜ 17.5 mag not present in optical bands. To unveil the nature of this feature we have derived the contribution of different galaxy types to the total K-band GNCs at 0.3galaxy evolutionary models, using deep multi-wavelength broad-band data in the Groth Strip region. We find that the slope change is due to a sudden swap of the galaxy population at z<1.5 that numerically dominates the total GNCs at z<1.5 (from quiescent E-S0s at K< 17.5 mag to blue star-forming disks at fainter magnitudes). Models in which the bulk of massive E-S0s were formed at high redshifts (z>2) and evolved passively since then cannot predict the slope change, whereas models that impose a late definitive assembly for them (at z<1.5) can reproduce it. We conclude that the slope change in total K-band GNCs is thus nothing other than a vestige of the definitive assembly of a substantial fraction (˜ 50%) of present-day massive E-S0s at 0.8galaxies at z<1.5 is necessary to confirm the late arrival of the bulk of massive galaxies to the Red Sequence.

  17. SERENDIPITOUS DISCOVERY OF A MASSIVE cD GALAXY AT z = 1.096: IMPLICATIONS FOR THE EARLY FORMATION AND LATE EVOLUTION OF cD GALAXIES

    SciTech Connect

    Liu, F. S.; Guo Yicheng; Koo, David C.; Trump, Jonathan R.; Barro, Guillermo; Yesuf, Hassen; Faber, S. M.; Cheung, Edmond; Cassata, P.; Koekemoer, A. M.; Grogin, Norman A.; Pentericci, L.; Castellano, M.; Mao, Shude; Xia, X. Y.; Hathi, Nimish P.; Huang, Kuang-Han; Kocevski, Dale; McGrath, Elizabeth J.; and others

    2013-06-01

    We have made a serendipitous discovery of a massive ({approx}5 Multiplication-Sign 10{sup 11} M{sub Sun }) cD galaxy at z = 1.096 in a candidate-rich cluster in the Hubble Ultra Deep Field (HUDF) area of GOODS-South. This brightest cluster galaxy (BCG) is the most distant cD galaxy confirmed to date. Ultra-deep HST/WFC3 images reveal an extended envelope starting from {approx}10 kpc and reaching {approx}70 kpc in radius along the semimajor axis. The spectral energy distributions indicate that both its inner component and outer envelope are composed of an old, passively evolving (specific star formation rate <10{sup -4} Gyr{sup -1}) stellar population. The cD galaxy lies on the same mass-size relation as the bulk of quiescent galaxies at similar redshifts. The cD galaxy has a higher stellar mass surface density ({approx}M{sub *}/R{sub 50}{sup 2}) but a similar velocity dispersion ({approx}{radical}(M{sub *}/R{sub 50})) to those of more massive, nearby cDs. If the cD galaxy is one of the progenitors of today's more massive cDs, its size (R{sub 50}) and stellar mass have had to increase on average by factors of 3.4 {+-} 1.1 and 3.3 {+-} 1.3 over the past {approx}8 Gyr, respectively. Such increases in size and stellar mass without being accompanied by significant increases in velocity dispersion are consistent with evolutionary scenarios driven by both major and minor dissipationless (dry) mergers. If such cD envelopes originate from dry mergers, our discovery of even one example proves that some BCGs entered the dry merger phase at epochs earlier than z = 1. Our data match theoretical models which predict that the continuance of dry mergers at z < 1 can result in structures similar to those of massive cD galaxies seen today. Moreover, our discovery is a surprise given that the extreme depth of the HUDF is essential to reveal such an extended cD envelope at z > 1 and, yet, the HUDF covers only a minuscule region of sky ({approx}3.1 Multiplication-Sign 10{sup -8

  18. Serendipitous Discovery of a Massive cD Galaxy at z = 1.096: Implications for the Early Formation and Late Evolution of cD Galaxies

    NASA Astrophysics Data System (ADS)

    Liu, F. S.; Guo, Yicheng; Koo, David C.; Trump, Jonathan R.; Barro, Guillermo; Yesuf, Hassen; Faber, S. M.; Giavalisco, M.; Cassata, P.; Koekemoer, A. M.; Pentericci, L.; Castellano, M.; Cheung, Edmond; Mao, Shude; Xia, X. Y.; Grogin, Norman A.; Hathi, Nimish P.; Huang, Kuang-Han; Kocevski, Dale; McGrath, Elizabeth J.; Wuyts, Stijn

    2013-06-01

    We have made a serendipitous discovery of a massive (~5 × 1011 M ⊙) cD galaxy at z = 1.096 in a candidate-rich cluster in the Hubble Ultra Deep Field (HUDF) area of GOODS-South. This brightest cluster galaxy (BCG) is the most distant cD galaxy confirmed to date. Ultra-deep HST/WFC3 images reveal an extended envelope starting from ~10 kpc and reaching ~70 kpc in radius along the semimajor axis. The spectral energy distributions indicate that both its inner component and outer envelope are composed of an old, passively evolving (specific star formation rate <10-4 Gyr-1) stellar population. The cD galaxy lies on the same mass-size relation as the bulk of quiescent galaxies at similar redshifts. The cD galaxy has a higher stellar mass surface density ({\\sim} M_*/R_{50}^2) but a similar velocity dispersion ({\\sim} \\sqrt{M_*/R_{50}}) to those of more massive, nearby cDs. If the cD galaxy is one of the progenitors of today's more massive cDs, its size (R 50) and stellar mass have had to increase on average by factors of 3.4 ± 1.1 and 3.3 ± 1.3 over the past ~8 Gyr, respectively. Such increases in size and stellar mass without being accompanied by significant increases in velocity dispersion are consistent with evolutionary scenarios driven by both major and minor dissipationless (dry) mergers. If such cD envelopes originate from dry mergers, our discovery of even one example proves that some BCGs entered the dry merger phase at epochs earlier than z = 1. Our data match theoretical models which predict that the continuance of dry mergers at z < 1 can result in structures similar to those of massive cD galaxies seen today. Moreover, our discovery is a surprise given that the extreme depth of the HUDF is essential to reveal such an extended cD envelope at z > 1 and, yet, the HUDF covers only a minuscule region of sky (~3.1 × 10-8). Adding that cDs are rare, our serendipitous discovery hints that such cDs may be more common than expected, perhaps even ubiquitous

  19. Galaxy population properties of the massive X-ray luminous galaxy cluster XDCP J0044.0-2033 at z = 1.58. Red-sequence formation, massive galaxy assembly, and central star formation activity

    NASA Astrophysics Data System (ADS)

    Fassbender, R.; Nastasi, A.; Santos, J. S.; Lidman, C.; Verdugo, M.; Koyama, Y.; Rosati, P.; Pierini, D.; Padilla, N.; Romeo, A. D.; Menci, N.; Bongiorno, A.; Castellano, M.; Cerulo, P.; Fontana, A.; Galametz, A.; Grazian, A.; Lamastra, A.; Pentericci, L.; Sommariva, V.; Strazzullo, V.; Šuhada, R.; Tozzi, P.

    2014-08-01

    Context. Recent observational progress has enabled the detection of galaxy clusters and groups out to very high redshifts and for the first time allows detailed studies of galaxy population properties in these densest environments in what was formerly known as the "redshift desert" at z> 1.5. Aims: We aim to investigate various galaxy population properties of the massive X-ray luminous galaxy cluster XDCP J0044.0-2033 at z = 1.58, which constitutes the most extreme currently known matter-density peak at this redshift. Methods: We analyzed deep VLT/HAWK-I near-infrared data with an image quality of 0.5'' and limiting Vega magnitudes (50% completeness) of 24.2 in J- and 22.8 in the Ks band, complemented by similarly deep Subaru imaging in i and V, Spitzer observations at 4.5 μm, and new spectroscopic observations with VLT/FORS 2. Results: We detect a cluster-associated excess population of about 90 galaxies, most of them located within the inner 30'' (250 kpc) of the X-ray centroid, which follows a centrally peaked, compact NFW galaxy surface-density profile with a concentration of c200 ≃ 10. Based on the Spitzer 4.5 μm imaging data, we measure a total enclosed stellar mass of M∗500 ≃ (6.3 ± 1.6) × 1012 M⊙ and a resulting stellar mass fraction of f∗,500 = M∗,500/M500 = (3.3 ± 1.4)%, consistent with local values. The total J- and Ks-band galaxy luminosity functions of the core region yield characteristic magnitudes J* and Ks* consistent with expectations from simple zf = 3 burst models. However, a detailed look at the morphologies and color distributions of the spectroscopically confirmed members reveals that the most massive galaxies are undergoing a very active mass-assembly epoch through merging processes. Consequently, the bright end of the cluster red sequence is not in place, while a red-locus population is present at intermediate magnitudes [Ks*, Ks* + 1.6], which is then sharply truncated at magnitudes fainter than Ks* + 1.6. The dominant

  20. Nonlinear structural response using adaptive dynamic relaxation on a massively-parallel-processing system

    NASA Technical Reports Server (NTRS)

    Oakley, David R.; Knight, Norman F., Jr.

    1994-01-01

    A parallel adaptive dynamic relaxation (ADR) algorithm has been developed for nonlinear structural analysis. This algorithm has minimal memory requirements, is easily parallelizable and scalable to many processors, and is generally very reliable and efficient for highly nonlinear problems. Performance evaluations on single-processor computers have shown that the ADR algorithm is reliable and highly vectorizable, and that it is competitive with direct solution methods for the highly nonlinear problems considered. The present algorithm is implemented on the 512-processor Intel Touchstone DELTA system at Caltech, and it is designed to minimize the extent and frequency of interprocessor communication. The algorithm has been used to solve for the nonlinear static response of two and three dimensional hyperelastic systems involving contact. Impressive relative speedups have been achieved and demonstrate the high scalability of the ADR algorithm. For the class of problems addressed, the ADR algorithm represents a very promising approach for parallel-vector processing.

  1. Lack of nuclear clusters in dwarf spheroidal galaxies: implications for massive black holes formation and the cusp/core problem

    NASA Astrophysics Data System (ADS)

    Arca-Sedda, Manuel; Capuzzo-Dolcetta, Roberto

    2017-01-01

    One of the leading scenarios for the formation of nuclear star clusters in galaxies is related to the orbital decay of globular clusters (GCs) and their subsequent merging, though alternative theories are currently debated. The availability of high-quality data for structural and orbital parameters of GCs allows us to test different nuclear star cluster formation scenarios. The Fornax dwarf spheroidal (dSph) galaxy is the heaviest satellite of the Milky Way and it is the only known dSph hosting five GCs, whereas there are no clear signatures for the presence of a central massive black hole. For this reason, it represents a suited place to study the orbital decay process in dwarf galaxies. In this paper, we model the future evolution of the Fornax GCs simulating them and the host galaxy by means of direct N-body simulations. Our simulations also take into account the gravitational field generated by the Milky Way. We found that if the Fornax galaxy is embedded in a standard cold dark matter halo, the nuclear cluster formation would be significantly hampered by the high central galactic mass density. In this context, we discuss the possibility that infalling GCs drive the flattening of the galactic density profile, giving a possible alternative explanation to the so-called cusp/core problem. Moreover, we briefly discuss the link between GC infall process and the absence of massive black holes in the centre of dSphs.

  2. Are “quiescent” galaxies really void of star formation? The mid-, far-infrared and radio properties of massive quiescent galaxies at z=0.1-3

    NASA Astrophysics Data System (ADS)

    Man, Allison W. S.; Greve, Thomas; Toft, Sune

    2015-08-01

    Quiescent galaxy candidates in deep field photometric surveys are typically identified by their low unobscured star formation rates. However, this assumes a universal dust attenuation curve, leading to possible misclassification of dusty star-forming galaxies as quiescent ones. Current surveys at mid-, far-infrared and radio wavelengths are limited to detecting only galaxies with very strong star formation or AGN activity. I will present the first comprehensive stacking results across mid-, far-infrared and radio wavelengths using Spitzer, Herschel and VLA data in the COSMOS field. We find that the rest-frame NUV-r and r-J color criteria, combined with low 24um emission, provides a robust selection of quiescent galaxies out to z=3 that have obscured star formation rates >10 times lower than those of star-forming galaxies. Additionally, we find evidence of radio emission in excess of the expected total star formation in quiescent galaxies at z~0-1.5, most notable for the massive ones, indicative of the ubiquity of low-luminosity radio AGN among them.

  3. Dry minor mergers and the size evolution of high-z compact massive early-type galaxies

    NASA Astrophysics Data System (ADS)

    Oogi, Taira; Habe, Asao

    2013-07-01

    Recent observations show evidence that high-z (z ~ 2 - 3) early-type galaxies (ETGs) are more compact than those with comparable mass at z ~ 0 (e.g. Trujillo et al. 2007; Buitrago et al. 2008). Such a size evolution is most likely explained by the `dry merger scenario'. However, previous studies based on this scenario are not able to consistently explain both the properties of the high-z compact massive ETGs and the local ETGs (Nipoti et al. 2009). We investigate the effect of multiple sequential minor mergers on the size evolution of the compact massive ETGs.

  4. The SL2S galaxy-scale lens sample. V. dark matter halos and stellar IMF of massive early-type galaxies out to redshift 0.8

    DOE PAGES

    Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; ...

    2015-02-17

    Here, we investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We also perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. Furthermore, we found that the dark matter mass projected within the innermore » 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M * = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.« less

  5. THE SL2S GALAXY-SCALE LENS SAMPLE. V. DARK MATTER HALOS AND STELLAR IMF OF MASSIVE EARLY-TYPE GALAXIES OUT TO REDSHIFT 0.8

    SciTech Connect

    Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; Suyu, Sherry H.; Gavazzi, Raphaël; Auger, Matthew W.; Nipoti, Carlo

    2015-02-20

    We investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. We find that the dark matter mass projected within the inner 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M {sub *} = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.

  6. The SL2S galaxy-scale lens sample. V. dark matter halos and stellar IMF of massive early-type galaxies out to redshift 0.8

    SciTech Connect

    Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; Suyu, Sherry H.; Gavazzi, Raphaël; Auger, Matthew W.; Nipoti, Carlo

    2015-02-17

    Here, we investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We also perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. Furthermore, we found that the dark matter mass projected within the inner 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M * = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.

  7. The SL2S Galaxy-scale Lens Sample. V. Dark Matter Halos and Stellar IMF of Massive Early-type Galaxies Out to Redshift 0.8

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; Suyu, Sherry H.; Gavazzi, Raphaël; Auger, Matthew W.; Nipoti, Carlo

    2015-02-01

    We investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. We find that the dark matter mass projected within the inner 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M * = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.

  8. Massive molecular gas flows in the a1664 brightest cluster galaxy

    SciTech Connect

    Russell, H. R.; McNamara, B. R.; Main, R. A.; Vantyghem, A. N.; Edge, A. C.; Wilman, R. J.; Nulsen, P. E. J.; Combes, F.; Salomé, P.; Fabian, A. C.; Murray, N.; Baum, S. A.; O'Dea, C. P.; Donahue, M.; Voit, G. M.; Oonk, J. B. R.; Tremblay, G. R.

    2014-03-20

    We report ALMA Early Science CO(1-0) and CO(3-2) observations of the brightest cluster galaxy (BCG) in A1664. The BCG contains 1.1 × 10{sup 10} M {sub ☉} of molecular gas divided roughly equally between two distinct velocity systems: one from –250 to +250 km s{sup –1} centered on the BCG's systemic velocity and a high-velocity system blueshifted by 570 km s{sup –1} with respect to the systemic velocity. The BCG's systemic component shows a smooth velocity gradient across the BCG center, suggestive of rotation about the nucleus. However, the mass and velocity structure are highly asymmetric and there is little star formation coincident with a putative disk. It may be an inflow of gas that will settle into a disk over several 10{sup 8} yr. The high-velocity system consists of two gas clumps, each ∼2 kpc across, located to the north and southeast of the nucleus. Each has a line of sight velocity spread of 250-300 km s{sup –1}. The velocity of the gas in the high-velocity system increases toward the BCG center and may be a massive flow into the nucleus. However, the velocity gradient is not smooth. These structures are also coincident with low optical-ultraviolet surface brightness regions, which could indicate dust extinction associated with each clump. The structure is complex, making a clear interpretation difficult, but if the dusty, molecular gas lies predominantly in front of the BCG, the blueshifted velocities would indicate an outflow. Based on the energy requirements, such a massive outflow would most likely be driven by the active galactic nucleus. A merger origin is unlikely but cannot be ruled out.

  9. EVIDENCE THAT GAMMA-RAY BURST 130702A EXPLODED IN A DWARF SATELLITE OF A MASSIVE GALAXY

    SciTech Connect

    Kelly, Patrick L.; Filippenko, Alexei V.; Fox, Ori D.; Zheng Weikang; Clubb, Kelsey I.

    2013-09-20

    GRB 130702A is a nearby long-duration gamma-ray burst (LGRB) discovered by the Fermi satellite whose associated afterglow was detected by the Palomar Transient Factory. Subsequent photometric and spectroscopic monitoring has identified a coincident broad-lined Type Ic supernova (SN), and nebular emission detected near the explosion site is consistent with a redshift of z = 0.145. The SN-GRB exploded at an offset of {approx}7.''6 from the center of an inclined r = 18.1 mag red disk-dominated galaxy, and {approx}0.''6 from the center of a much fainter r = 23 mag object. We obtained Keck-II DEIMOS spectra of the two objects and find a 2{sigma} upper limit on their line-of-sight velocity offset of {approx}<60 km s{sup -1}. If we calculate the inclination angle of the massive red galaxy from its axis ratio and assume that its light is dominated by a very thin disk, the explosion would have a {approx}60 kpc central offset, or {approx}9 times the galaxy's half-light radius. A significant bulge or a thicker disk would imply a higher inclination angle and greater central offset. The substantial offset suggests that the faint source is a separate dwarf galaxy. The star-formation rate of the dwarf galaxy is {approx}0.05 M{sub Sun} yr{sup -1}, and we place an upper limit on its oxygen abundance of 12 + log(O/H) < 8.16 dex. The identification of an LGRB in a dwarf satellite of a massive, metal-rich primary galaxy suggests that recent detections of LGRBs spatially coincident with metal-rich galaxies may be, in some cases, superpositions.

  10. The Ages, Metallicities, and Element Abundance Ratios of Massive Quenched Galaxies at z ≥ 1.6

    NASA Astrophysics Data System (ADS)

    Onodera, M.; Carollo, C. M.; Renzini, A.; Cappellari, M.; Mancini, C.; Arimoto, N.; Daddi, E.; Gobat, R.; Strazzullo, V.; Tacchella, S.; Yamada, Y.

    2015-08-01

    We investigate the stellar population properties of a sample of 24 massive quenched galaxies at 1.25< zspec< 2.09 identified in the COSMOS field with our Subaru/Multi-object Infrared Camera and Spectrograph near-IR spectroscopic observations. Tracing the stellar population properties as close to their major formation epoch as possible, we try to put constraints on the star formation history, post-quenching evolution, and possible progenitor star-forming populations for such massive quenched galaxies. By using a set of Lick absorption line indices on a rest-frame optical composite spectrum, the average age, metallicity [Z/H], and α-to-iron element abundance ratio [α/Fe] are derived as log(age/Gyr)=0.04-0.08+0.10, [Z/H]=0.24-0.14+0.20, and [α /Fe]=0.31-0.12+0.12, respectively. If our sample of quenched galaxies at < z≥1.6 is evolved passively to z = 0, their stellar population properties will align in excellent agreement with local counterparts at similar stellar velocity dispersions, which qualifies them as progenitors of local massive early-type galaxies. Redshift evolution of stellar population ages in quenched galaxies combined with low redshift measurements from the literature suggests a formation redshift of zf∼ 2.3, around which the bulk of stars in these galaxies have been formed. The measured [α/Fe] value indicates a star formation timescale of ≲ 1 Gyr, which can be translated into a specific star formation rate of ≃ 1 Gyr-1 prior to quenching. Based on these findings, we discuss identifying possible progenitor star-forming galaxies at z≃ 2.3. We identify normal star-forming galaxies, i.e., those on the star-forming main sequence, followed by a rapid quenching event, as likely precursors of the quenched galaxies at < z≥1.6 presented here. Based on data collected at the Subaru telescope, which is operated by the National Astronomical Observatory of Japan. (Proposal IDs: S09A-043, S10A-058, and S11A-075.)

  11. The challenging task of determining star formation rates: the case of a massive stellar burst in the brightest cluster galaxy of Phoenix galaxy cluster

    NASA Astrophysics Data System (ADS)

    Mittal, Rupal; McDonald, M.; Whelan, John T.; Bruzual, Gustavo

    2017-03-01

    Star formation in galaxies at the centre of cooling-flow galaxy clusters is an important phenomenon in the context of formation and evolution of massive galaxies in the Universe. Yet, star formation rates (SFRs) in such systems continue to be elusive. We use our Bayesian-motivated spectral energy distribution (SED)-fitting code, BAYESCOOL, to estimate the plausible SFR values in the brightest cluster galaxy of a massive, X-ray luminous galaxy cluster, Phoenix. Previous studies of Phoenix have resulted in the highest measurement of SFR for any galaxy, with the estimates reaching up to 1000 M⊙ yr-1. However, a very small number of models have been considered in those studies. BAYESCOOL allows us to probe a large parameter space. We consider two models for star formation history, instantaneous bursts and continuous star formation, a wide range of ages for the old and the young stellar population, along with other discrete parameters, such as the initial mass function, metallicities, internal extinction and extinction law. We find that in the absence of any prior except that the maximum cooling rate <3000 M⊙ yr-1, the SFR lies in the range (2230 - 2890) M⊙ yr-1. If we impose an observational prior on the internal extinction, E(B-V) < 0.6, the best-fitting SFR lies in (454 - 494) M⊙ yr-1, and we consider this as the most probable range of SFR values for Phoenix. The SFR dependence on the extinction is a reflection of the standard age-extinction degeneracy, which can be overcome by using a prior on one of the two quantities in question.

  12. Evidence for the Suppression of Star-Formation in the Centers of Massive Galaxies at z=4

    NASA Astrophysics Data System (ADS)

    JUNG, INTAE; Finkelstein, Steven L.; CANDELS Team

    2016-01-01

    We perform the first spatially-resolved stellar population study of galaxies over the GOODS-S field in the early universe (z = 3.5-6.5), utilizing the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) imaging dataset. We select a sample of ~ 550 bright and extended galaxies at z = 3.5-6.5, from a parent sample of ~ 8000 photometric-redshift selected galaxies at z = 3.5-8.5 (Finkelstein et al. 2015). We separate each galaxy into several concentric rings with various radial distances to the galactic center, and perform aperture photometry to calculate the fluxes from each annulus. We derive the radial dependence of the galaxy properties such as stellar mass, star formation rate, and dust content via spectral energy distribution fitting based on a Markov Chain Monte Carlo algorithm. We find that in our highest two redshift bins (z ~ 5 and 6), our sample of galaxies show specific star formation rates (sSFRs) which are generally independent of the radial distance from the center of the galaxies, indicating that stars are formed uniformly at all radii, contrary to massive galaxies at z ≤ 2. However, in our lowest redshift bin of z ~ 4, the majority of galaxies with the highest central mass densities (log M/M⊙ > 9 kpc-2) show evidence for a preferentially lower sSFR in their centers than in their outer regions, indicative of the suppression of star formation in their central regions, possibly leading to the formation of bulges.

  13. Morphology Dependence of Stellar Age in Quenched Galaxies at Redshift ∼1.2: Massive Compact Galaxies Are Older than More Extended Ones

    NASA Astrophysics Data System (ADS)

    Williams, Christina C.; Giavalisco, Mauro; Bezanson, Rachel; Cappelluti, Nico; Cassata, Paolo; Liu, Teng; Lee, Bomee; Tundo, Elena; Vanzella, Eros

    2017-04-01

    We report the detection of morphology-dependent stellar age in massive quenched galaxies (QGs) at z ∼ 1.2. The sense of the dependence is that compact QGs are 0.5–2 Gyr older than normal-sized ones. The evidence comes from three different age indicators—{D}n4000, {{{H}}}δ , and fits to spectral synthesis models—applied to their stacked optical spectra. All age indicators consistently show that the stellar populations of compact QGs are older than those of their normal-sized counterparts. We detect weak [O ii] emission in a fraction of QGs, and the strength of the line, when present, is similar between the two samples; however, compact galaxies exhibit a significantly lower frequency of [O ii] emission than normal ones. Fractions of both samples are individually detected in 7 Ms Chandra X-ray images (luminosities ∼1040–1041 erg s‑1). The 7 Ms stacks of nondetected galaxies show similarly low luminosities in the soft band only, consistent with a hot gas origin for the X-ray emission. While both [O ii] emitters and nonemitters are also X-ray sources among normal galaxies, no compact galaxy with [O ii] emission is an X-ray source, arguing against an active galactic nucleus (AGN) powering the line in compact galaxies. We interpret the [O ii] properties as further evidence that compact galaxies are older and further along in the process of quenching star formation and suppressing gas accretion. Finally, we argue that the older age of compact QGs is evidence of progenitor bias: compact QGs simply reflect the smaller sizes of galaxies at their earlier quenching epoch, with stellar density most likely having nothing directly to do with cessation of star formation.

  14. The inside-out growth of the most massive galaxies at 0.3 < z < 0.9

    SciTech Connect

    Bai, Lei; Yee, H. K. C.; Li, I. H.; Yan, Renbin; Lee, Eve; Gilbank, David G.; Ellingson, E.; Barrientos, L. F.; Gladders, M. D.; Hsieh, B. C.

    2014-07-10

    We study the surface brightness profiles of a sample of brightest cluster galaxies (BCGs) with 0.3 < z < 0.9. The BCGs are selected from the first Red-sequence Cluster Survey and an X-ray cluster survey. The surface brightness profiles of the BCGs are measured using HST ACS images, and the majority of them can be well modeled by a single Sérsic profile with a typical Sérsic index n ∼ 6 and a half-light radius ∼30 kpc. Although the single Sérsic model fits the profiles well, we argue that the systematics in the sky background measurement and the coupling between the model parameters make the comparison of the best-fit model parameters ambiguous. Direct comparison of the BCG profiles, on the other hand, has revealed an inside-out growth for these most massive galaxies: as the mass of a BCG increases, the central mass density of the galaxy increases slowly (ρ{sub 1kpc}∝M{sub ∗}{sup 0.39}), while the slope of the outer profile grows continuously shallower (α{sub r{sup 1}{sup /}{sup 4}}∝M{sub ∗}{sup −2.5}). Such a fashion of growth continues down to the less massive early-type galaxies (ETGs) as a smooth function of galaxy mass, without apparent distinction between BCGs and non-BCGs. For the very massive ETGs and BCGs, the slope of the Kormendy relation starts to trace the slope of the surface brightness profiles and becomes insensitive to subtle profile evolution. These results are generally consistent with dry mergers being the major driver of the mass growth for BCGs and massive ETGs. We also find strong correlations between the richness of clusters and the properties of BCGs: the more massive the clusters are, the more massive the BCGs (M{sub bcg}{sup ∗}∝M{sub clusters}{sup 0.6}) and the shallower their surface brightness profiles. After taking into account the bias in the cluster samples, we find the masses of the BCGs have grown by at least a factor of 1.5 from z = 0.5 to z = 0, in contrast to the previous findings of no evolution. Such an

  15. The Inside-out Growth of the Most Massive Galaxies at 0.3 < z < 0.9

    NASA Astrophysics Data System (ADS)

    Bai, Lei; Yee, H. K. C.; Yan, Renbin; Lee, Eve; Gilbank, David G.; Ellingson, E.; Barrientos, L. F.; Gladders, M. D.; Hsieh, B. C.; Li, I. H.

    2014-07-01

    We study the surface brightness profiles of a sample of brightest cluster galaxies (BCGs) with 0.3 < z < 0.9. The BCGs are selected from the first Red-sequence Cluster Survey and an X-ray cluster survey. The surface brightness profiles of the BCGs are measured using HST ACS images, and the majority of them can be well modeled by a single Sérsic profile with a typical Sérsic index n ~ 6 and a half-light radius ~30 kpc. Although the single Sérsic model fits the profiles well, we argue that the systematics in the sky background measurement and the coupling between the model parameters make the comparison of the best-fit model parameters ambiguous. Direct comparison of the BCG profiles, on the other hand, has revealed an inside-out growth for these most massive galaxies: as the mass of a BCG increases, the central mass density of the galaxy increases slowly (\\rho _{1\\,kpc} \\propto M_{*}^{0.39}), while the slope of the outer profile grows continuously shallower (\\alpha _{r^{1/4}} \\propto M_{*}^{-2.5}). Such a fashion of growth continues down to the less massive early-type galaxies (ETGs) as a smooth function of galaxy mass, without apparent distinction between BCGs and non-BCGs. For the very massive ETGs and BCGs, the slope of the Kormendy relation starts to trace the slope of the surface brightness profiles and becomes insensitive to subtle profile evolution. These results are generally consistent with dry mergers being the major driver of the mass growth for BCGs and massive ETGs. We also find strong correlations between the richness of clusters and the properties of BCGs: the more massive the clusters are, the more massive the BCGs (M^{*}_{bcg} \\propto M_{clusters}^{0.6}) and the shallower their surface brightness profiles. After taking into account the bias in the cluster samples, we find the masses of the BCGs have grown by at least a factor of 1.5 from z = 0.5 to z = 0, in contrast to the previous findings of no evolution. Such an evolution validates the

  16. Massive primordial black holes from hybrid inflation as dark matter and the seeds of galaxies

    NASA Astrophysics Data System (ADS)

    Clesse, Sébastien; García-Bellido, Juan

    2015-07-01

    In this paper we present a new scenario where massive primordial black holes (PBHs) are produced from the collapse of large curvature perturbations generated during a mild-waterfall phase of hybrid inflation. We determine the values of the inflaton potential parameters leading to a PBH mass spectrum peaking on planetarylike masses at matter-radiation equality and producing abundances comparable to those of dark matter today, while the matter power spectrum on scales probed by cosmic microwave background (CMB) anisotropies agrees with Planck data. These PBHs could have acquired large stellar masses today, via merging, and the model passes both the constraints from CMB distortions and microlensing. This scenario is supported by Chandra observations of numerous BH candidates in the central region of Andromeda. Moreover, the tail of the PBH mass distribution could be responsible for the seeds of supermassive black holes at the center of galaxies, as well as for ultraluminous x-ray sources. We find that our effective hybrid potential can originate e.g. from D-term inflation with a Fayet-Iliopoulos term of the order of the Planck scale but sub-Planckian values of the inflaton field. Finally, we discuss the implications of quantum diffusion at the instability point of the potential, able to generate a Swiss-cheese-like structure of the Universe, eventually leading to apparent accelerated cosmic expansion.

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

    SciTech Connect

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

    2004-03-02

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

  18. PROBING THE INNER KILOPARSEC OF MASSIVE GALAXIES WITH STRONG GRAVITATIONAL LENSING

    SciTech Connect

    Hezaveh, Yashar D.; Marshall, Philip J.; Blandford, Roger D.

    2015-01-30

    We examine the prospects of detecting demagnified images of gravitational lenses in observations of strongly lensed millimeter-wave molecular emission lines with ALMA. We model the lensing galaxies as a superposition of a dark matter component, a stellar component, and a central super-massive black hole (SMBH) and assess the detectability of the central images for a range of relevant parameters (e.g., stellar core, black hole mass, and source size). We find that over a large range of plausible parameters, future deep observations of lensed molecular lines with ALMA should enable the detection of the central images at ≳3σ significance. We use a Fisher analysis to examine the constraints that could be placed on these parameters in various scenarios and find that for large stellar cores, both the core size and the mass of the central SMBHs can be accurately measured. We also study the prospects for detecting binary SMBHs with such observations and find that only under rare conditions and with very long integrations (∼40 hr) the masses of both SMBHs may be measured using the distortions of central images.

  19. Inflow velocities of cold flows streaming into massive galaxies at high redshifts

    NASA Astrophysics Data System (ADS)

    Goerdt, Tobias; Ceverino, Daniel

    2015-07-01

    We study the velocities of the accretion along streams from the cosmic web into massive galaxies at high redshift with the help of three different suites of AMR hydrodynamical cosmological simulations. The results are compared to free-fall velocities and to the sound speeds of the hot ambient medium. The sound speed of the hot ambient medium is calculated using two different methods to determine the medium's temperature. We find that the simulated cold stream velocities are in violent disagreement with the corresponding free-fall profiles. The sound speed is a better albeit not always correct description of the cold flows' velocity. Using these calculations as a first order approximation for the gas inflow velocities vinflow = 0.9 vvir is given. We conclude from the hydrodynamical simulations as our main result that the velocity profiles for the cold streams are constant with radius. These constant inflow velocities seem to have a `parabola-like' dependency on the host halo mass in units of the virial velocity that peaks at Mvir = 1012 M⊙ and we also propose that the best-fitting functional form for the dependency of the inflow velocity on the redshift is a square root power-law relation: v_inflow ∝ √{z + 1} v_vir.

  20. A MASSIVE MOLECULAR GAS RESERVOIR IN THE z = 5.3 SUBMILLIMETER GALAXY AzTEC-3

    SciTech Connect

    Riechers, Dominik A.; Scoville, Nicholas Z.; Capak, Peter L.; Yan, Lin; Carilli, Christopher L.; Cox, Pierre; Neri, Roberto; Schinnerer, Eva; Bertoldi, Frank

    2010-09-10

    We report the detection of CO J = 2{yields}1, 5{yields}4, and 6{yields}5 emission in the highest-redshift submillimeter galaxy (SMG) AzTEC-3 at z = 5.298, using the Expanded Very Large Array and the Plateau de Bure Interferometer. These observations ultimately confirm the redshift, making AzTEC-3 the most submillimeter-luminous galaxy in a massive z {approx_equal} 5.3 protocluster structure in the COSMOS field. The strength of the CO line emission reveals a large molecular gas reservoir with a mass of 5.3 x 10{sup 10}({alpha}{sub CO}/0.8) M {sub sun}, which can maintain the intense 1800 M {sub sun} yr{sup -1} starburst in this system for at least 30 Myr, increasing the stellar mass by up to a factor of six in the process. This gas mass is comparable to 'typical' z {approx} 2 SMGs and constitutes {approx_gt}80% of the baryonic mass (gas+stars) and 30%-80% of the total (dynamical) mass in this galaxy. The molecular gas reservoir has a radius of <4 kpc and likely consists of a 'diffuse', low-excitation component, containing (at least) 1/3 of the gas mass (depending on the relative conversion factor {alpha}{sub CO}), and a 'dense', high-excitation component, containing {approx}2/3 of the mass. The likely presence of a substantial diffuse component besides highly excited gas suggests different properties between the star-forming environments in z > 4 SMGs and z > 4 quasar host galaxies, which perhaps trace different evolutionary stages. The discovery of a massive, metal-enriched gas reservoir in an SMG at the heart of a large z = 5.3 protocluster considerably enhances our understanding of early massive galaxy formation, pushing back to a cosmic epoch where the universe was less than 1/12 of its present age.

  1. Stellar population properties of the most massive globular clusters and ultra-compact dwarf galaxies of the Fornax cluster

    NASA Astrophysics Data System (ADS)

    Hilker, Michael

    2017-03-01

    Most ultra-compact dwarf galaxies (UCDs) and very massive globular clusters reside in nearby galaxy clusters or around nearby giant galaxies. Due to their distance (> 4 Mpc) and compactness (r eff < 100 pc) they are barely resolved, and thus it is difficult to obtain their internal properties. Here I present our most recent attempts to constrain the mass function, stellar content and dynamical state of UCDs in the Fornax cluster. Thanks to radial velocity membership assignment of ~ 950 globular clusters (GCs) and UCDs in the core of Fornax, the shape of their mass function is well constrained. It is consistent with the `standard' Gaussian mass function of GCs. Our recent simulations on the disruption process of nucleated dwarf galaxies in cluster environments showed that ~ 40% of the most massive UCDs should originate from nuclear star clusters. Some Fornax UCDs actually show evidence for this scenario, as revealed by extended low surface brightness disks around them and onsets of tidal tails. Multi-band UV to optical imaging as well as low to medium resolution spectroscopy revealed that there exist UCDs with youngish ages, (sub-)solar [α/Fe] abundances, and probably He-enriched populations.

  2. The Structure and Dynamics of Massive Early-Type Galaxies: On Homology, Isothermality, and Isotropy Inside One Effective Radius

    NASA Astrophysics Data System (ADS)

    Koopmans, L. V. E.; Bolton, A.; Treu, T.; Czoske, O.; Auger, M. W.; Barnabè, M.; Vegetti, S.; Gavazzi, R.; Moustakas, L. A.; Burles, S.

    2009-09-01

    Based on 58 SLACS strong-lens early-type galaxies (ETGs) with direct total-mass and stellar-velocity dispersion measurements, we find that inside one effective radius massive elliptical galaxies with M eff gsim 3 × 1010 M sun are well approximated by a power-law ellipsoid, with an average logarithmic density slope of langγ'LDrang ≡ -dlog(ρtot)/dlog(r) = 2.085+0.025 -0.018 (random error on mean) for isotropic orbits with β r = 0, ±0.1 (syst.) and σ_{γ'} ≲ 0.20^{+0.04}_{-0.02} intrinsic scatter (all errors indicate the 68% CL). We find no correlation of γ'LD with galaxy mass (M eff), rescaled radius (i.e., R einst/R eff) or redshift, despite intrinsic differences in density-slope between galaxies. Based on scaling relations, the average logarithmic density slope can be derived in an alternative manner, fully independent from dynamics, yielding langγ'SRrang = 1.959 ± 0.077. Agreement between the two values is reached for langβ r rang = 0.45 ± 0.25, consistent with mild radial anisotropy. This agreement supports the robustness of our results, despite the increase in mass-to-light ratio with total galaxy mass: M eff vprop L 1.363±0.056 V,eff. We conclude that massive ETGs are structurally close to homologous with close to isothermal total density profiles (lsim10% intrinsic scatter) and have at most some mild radial anisotropy. Our results provide new observational limits on galaxy formation and evolution scenarios, covering 4 Gyr look-back time.

  3. Galaxy Populations in Massive Galaxy Clusters to z = 1.1: Color Distribution, Concentration, Halo Occupation Number and Red Sequence Fraction

    NASA Astrophysics Data System (ADS)

    Hennig, C.; Mohr, J. J.; Zenteno, A.; Desai, S.; Dietrich, J. P.; Bocquet, S.; Strazzullo, V.; Saro, A.; Abbott, T. M. C.; Abdalla, F. B.; Bayliss, M.; Benoit-Lévy, A.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Capasso, R.; Capozzi, D.; Carnero, A.; Kind, M. Carrasco; Carretero, J.; Chiu, I.; D'Andrea, C. B.; daCosta, L. N.; Diehl, H. T.; Doel, P.; Eifler, T. F.; Evrard, A. E.; Fausti-Neto, A.; Fosalba, P.; Frieman, J.; Gangkofner, C.; Gonzalez, A.; Gruen, D.; Gruendl, R. A.; Gupta, N.; Gutierrez, G.; Honscheid, K.; Hlavacek-Larrondo, J.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; March, M.; Marshall, J. L.; Martini, P.; McDonald, M.; Melchior, P.; Miller, C. J.; Miquel, R.; Neilsen, E.; Nord, B.; Ogando, R.; Plazas, A. A.; Reichardt, C.; Romer, A. K.; Rozo, E.; Rykoff, E. S.; Sanchez, E.; Santiago, B.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Stalder, B.; Stanford, S. A.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Vikram, V.; Walker, A. R.; Zhang, Y.

    2017-01-01

    We study the galaxy populations in 74 Sunyaev Zeldovich Effect (SZE) selected clusters from the South Pole Telescope (SPT) survey that have been imaged in the science verification phase of the Dark Energy Survey (DES). The sample extends up to z ˜ 1.1 with 4 × 1014M⊙ ≤ M200 ≤ 3 × 1015M⊙. Using the band containing the 4000 Å break and its redward neighbor, we study the color-magnitude distributions of cluster galaxies to ˜m★ + 2, finding: (1) the intrinsic rest frame g - r color width of the red sequence (RS) population is ˜0.03 out to z ˜ 0.85 with a preference for an increase to ˜0.07 at z = 1 and (2) the prominence of the RS declines beyond z ˜ 0.6. The spatial distribution of cluster galaxies is well described by the NFW profile out to 4R200 with a concentration of cg = 3.59^{+0.20}_{-0.18}, 5.37^{+0.27}_{-0.24} and 1.38^{+0.21}_{-0.19} for the full, the RS and the blue non-RS populations, respectively, but with ˜40% to 55% cluster to cluster variation and no statistically significant redshift or mass trends. The number of galaxies within the virial region N200 exhibits a mass trend indicating that the number of galaxies per unit total mass is lower in the most massive clusters, and shows no significant redshift trend. The red sequence (RS) fraction within R200 is (68 ± 3)% at z = 0.46, varies from ˜55% at z = 1 to ˜80% at z = 0.1, and exhibits intrinsic variation among clusters of ˜14%. We discuss a model that suggests the observed redshift trend in RS fraction favors a transformation timescale for infalling field galaxies to become RS galaxies of 2 to 3 Gyr.

  4. The trace of a substantial assembly of massive E-S0 galaxies at 0.8 < z < 1.5 in galaxy number counts

    NASA Astrophysics Data System (ADS)

    Prieto, Mercedes; Eliche-Moral, M. Carmen

    2015-08-01

    K-band galaxy number counts (GNCs) exhibit a slope change at K ˜ 17.5 mag not present in optical bands. To unveil the nature of this feature, we have derived the contribution of different galaxy types to the total K-band GNCs at 0.3 < z < 1.5 by redshift bins and compared the results with expectations from several galaxy evolutionary models. We show that the slope change is caused by a sudden swap of the galaxy population that numerically dominates the total GNCs (from quiescent E-S0's at K < 17.5 mag to blue star-forming discs at fainter magnitudes), and that it is associated with a flattening of the contribution of the E-S0's at 0.6 < z < 1 to the total GNCs. We confirm previous studies showing that models in which the bulk of massive E-S0's have evolved passively since z > 2 cannot predict the slope change, whereas those imposing a relatively late assembly on them (z < 1.5) can reproduce it. The K-band GNCs by redshift bins and morphological types point to a progressively definitive build-up of ˜50 per cent of this galaxy population at 0.8 < z < 1.5, which can be explained only through the major mergers reported by observations. We conclude that the slope change in total K-band GNCs is a vestige of the definitive assembly of a substantial fraction of present-day massive E-S0's at 0.8 < z < 1.5.

  5. COSMIC EVOLUTION OF VIRIAL AND STELLAR MASS IN MASSIVE EARLY-TYPE GALAXIES

    SciTech Connect

    Lagattuta, David J.; Fassnacht, Christopher D.; Auger, Matthew W.; Marshall, Philip J.; Bradac, Marusa; Treu, Tommaso; Gavazzi, Raphael; Schrabback, Tim; Faure, Cecile; Anguita, Timo

    2010-06-20

    We measure the average mass properties of a sample of 41 strong gravitational lenses at moderate redshift (z {approx} 0.4-0.9) and present the lens redshift for six of these galaxies for the first time. Using the techniques of strong and weak gravitational lensing on archival data obtained from the Hubble Space Telescope, we determine that the average mass overdensity profile of the lenses can be fit with a power-law profile ({Delta}{Sigma} {proportional_to} R {sup -0.86{+-}0.16}) that is within 1{sigma} of an isothermal profile ({Delta}{Sigma} {proportional_to} R {sup -1}) with velocity dispersion {sigma}{sub v} = 260 {+-} 20 km s{sup -1}. Additionally, we use a two-component de Vaucouleurs + Navarro-Frenk-White (NFW) model to disentangle the total mass profile into separate luminous and dark matter components and determine the relative fraction of each component. We measure the average rest frame V-band stellar mass-to-light ratio (Y{sub V} = 4.0 {+-} 0.6 h M{sub sun}/L{sub sun}) and virial mass-to-light ratio ({tau}{sub V} = 300 {+-} 90 h M{sub sun}/L{sub sun}) for our sample, resulting in a virial-to-stellar mass ratio of M{sub vir}/M{sub *} = 75 {+-} 25. Relaxing the NFW assumption, we estimate that changing the inner slope of the dark matter profile by {approx}20% yields a {approx}30% change in stellar mass-to-light ratio. Finally, we compare our results to a previous study using low-redshift lenses to understand how galaxy mass profiles evolve over time. We investigate the evolution of M{sub vir}/M{sub *}(z) = {alpha}(1 + z){sup {beta}}, and find best-fit parameters of {alpha} = 51 {+-} 36 and {beta} = 0.9 {+-} 1.8, constraining the growth of virial-to-stellar mass ratio over the last {approx}7 Gyr. We note that, by using a sample of strong lenses, we are able to constrain the growth of M{sub vir}/M{sub *}(z) without making any assumptions about the initial mass function of the stellar population.

  6. Observational evidence of a slow downfall of star formation efficiency in massive galaxies during the past 10 Gyr

    NASA Astrophysics Data System (ADS)

    Schreiber, C.; Elbaz, D.; Pannella, M.; Ciesla, L.; Wang, T.; Koekemoer, A.; Rafelski, M.; Daddi, E.

    2016-05-01

    We study the causes of the reported mass-dependence in the slope of the SFR-M∗ relation, the so-called main sequence of star-forming galaxies, and discuss its implication on the physical processes that shaped the star formation history of massive galaxies over cosmic time. We made use of the near-infrared high-resolution imaging from the Hubble Space Telescope in the CANDELS fields to perform a careful bulge-to-disk decomposition of distant galaxies and measure for the first time the slope of the SFR-Mdisk relation at z = 1. We find that this relation very closely follows the shape of the nominal SFR-M∗ correlation, still with a pronounced flattening at the high-mass end. This clearly excludes, at least at z = 1, the progressive growth of quiescent stellar bulges in star-forming galaxies as the main driver for the change of slope of the main sequence. Then, by stacking the Herschel data available in the CANDELS field, we estimated the gas mass (Mgas = MH i + MH2) and the star formation efficiency (SFE ≡ SFR/Mgas) at different positions on the SFR-M∗ relation. We find that the relatively low SFRs observed in massive galaxies (M∗> 5 × 1010 M⊙) are not caused by a reduced gas content, but by a star formation efficiency that is lower by up to a factor of 3 than in galaxies with lower stellar mass. The trend at the lowest masses is probably linked to the dominance of atomic over molecular gas. We argue that this stellar-mass-dependent SFE can explain the varying slope of the main sequence since z = 1.5, hence over 70% of the Hubble time. The drop in SFE occurs at lower masses in the local Universe (M∗> 2 × 1010 M⊙) and is not present at z = 2. Altogether, this provides evidence for a slow decrease in star formation efficiency in massive main sequence galaxies. The resulting loss of star formation is found to be rising starting from z = 2 to reach a level similar to the mass growth of the quiescent population by z = 1. We finally discuss the possible

  7. The Sins/zC-Sinf Survey of z ~ 2 Galaxy Kinematics: Evidence for Powerful Active Galactic Nucleus-Driven Nuclear Outflows in Massive Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Förster Schreiber, N. M.; Genzel, R.; Newman, S. F.; Kurk, J. D.; Lutz, D.; Tacconi, L. J.; Wuyts, S.; Bandara, K.; Burkert, A.; Buschkamp, P.; Carollo, C. M.; Cresci, G.; Daddi, E.; Davies, R.; Eisenhauer, F.; Hicks, E. K. S.; Lang, P.; Lilly, S. J.; Mainieri, V.; Mancini, C.; Naab, T.; Peng, Y.; Renzini, A.; Rosario, D.; Shapiro Griffin, K.; Shapley, A. E.; Sternberg, A.; Tacchella, S.; Vergani, D.; Wisnioski, E.; Wuyts, E.; Zamorani, G.

    2014-05-01

    We report the detection of ubiquitous powerful nuclear outflows in massive (>=1011 M ⊙) z ~ 2 star-forming galaxies (SFGs), which are plausibly driven by an active galactic nucleus (AGN). The sample consists of the eight most massive SFGs from our SINS/zC-SINF survey of galaxy kinematics with the imaging spectrometer SINFONI, six of which have sensitive high-resolution adaptive optics-assisted observations. All of the objects are disks hosting a significant stellar bulge. The spectra in their central regions exhibit a broad component in Hα and forbidden [N II] and [S II] line emission, with typical velocity FWHM ~ 1500 km s-1, [N II]/Hα ratio ≈ 0.6, and intrinsic extent of 2-3 kpc. These properties are consistent with warm ionized gas outflows associated with Type 2 AGN, the presence of which is confirmed via independent diagnostics in half the galaxies. The data imply a median ionized gas mass outflow rate of ~60 M ⊙ yr-1 and mass loading of ~3. At larger radii, a weaker broad component is detected but with lower FWHM ~485 km s-1 and [N II]/Hα ≈ 0.35, characteristic for star formation-driven outflows as found in the lower-mass SINS/zC-SINF galaxies. The high inferred mass outflow rates and frequent occurrence suggest that the nuclear outflows efficiently expel gas out of the centers of the galaxies with high duty cycles and may thus contribute to the process of star formation quenching in massive galaxies. Larger samples at high masses will be crucial in confirming the importance and energetics of the nuclear outflow phenomenon and its connection to AGN activity and bulge growth. Based on observations obtained at the Very Large Telescope of the European Southern Observatory, Paranal, Chile (ESO program IDs 074.A-0911, 075.A-0466, 076.A-0527, 078.A-0600, 082.A-0396, 183.A-0781, 088.A-0202, 091.A-0126). Also based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the

  8. Numerical Simulations Challenged on the Prediction of Massive Subhalo Abundance in Galaxy Clusters: The Case of Abell 2142

    NASA Astrophysics Data System (ADS)

    Munari, E.; Grillo, C.; De Lucia, G.; Biviano, A.; Annunziatella, M.; Borgani, S.; Lombardi, M.; Mercurio, A.; Rosati, P.

    2016-08-01

    In this Letter we compare the abundance of the member galaxies of a rich, nearby (z = 0.09) galaxy cluster, Abell 2142, with that of halos of comparable virial mass extracted from sets of state-of-the-art numerical simulations, both collisionless at different resolutions and with the inclusion of baryonic physics in the form of cooling, star formation, and feedback by active galactic nuclei. We also use two semi-analytical models to account for the presence of orphan galaxies. The photometric and spectroscopic information, taken from the Sloan Digital Sky Survey Data Release 12 database, allows us to estimate the stellar velocity dispersion of member galaxies of Abell 2142. This quantity is used as proxy for the total mass of secure cluster members and is properly compared with that of subhalos in simulations. We find that simulated halos have a statistically significant (≳ 7 sigma confidence level) smaller amount of massive (circular velocity above 200 {km} {{{s}}}-1) subhalos, even before accounting for the possible incompleteness of observations. These results corroborate the findings from a recent strong lensing study of the Hubble Frontier Fields galaxy cluster MACS J0416 and suggest that the observed difference is already present at the level of dark matter (DM) subhalos and is not solved by introducing baryonic physics. A deeper understanding of this discrepancy between observations and simulations will provide valuable insights into the impact of the physical properties of DM particles and the effect of baryons on the formation and evolution of cosmological structures.

  9. A population of massive, luminous galaxies hosting heavily dust-obscured gamma-ray bursts: Implications for the use of GRBs as tracers of cosmic star formation

    SciTech Connect

    Perley, D. A.; Levan, A. J.; Tanvir, N. R.; Cenko, S. B.; Bloom, J. S.; Filippenko, A. V.; Morgan, A. N.; Hjorth, J.; Krühler, T.; Fynbo, J. P. U.; Milvang-Jensen, B.; Fruchter, A.; Kalirai, J.; Jakobsson, P.; Prochaska, J. X.

    2013-12-01

    We present observations and analysis of the host galaxies of 23 heavily dust-obscured gamma-ray bursts (GRBs) observed by the Swift satellite during the years 2005-2009, representing all GRBs with an unambiguous host-frame extinction of A{sub V} > 1 mag from this period. Deep observations with Keck, Gemini, Very Large Telescope, Hubble Space Telescope, and Spitzer successfully detect the host galaxies and establish spectroscopic or photometric redshifts for all 23 events, enabling us to provide measurements of the intrinsic host star formation rates, stellar masses, and mean extinctions. Compared to the hosts of unobscured GRBs at similar redshifts, we find that the hosts of dust-obscured GRBs are (on average) more massive by about an order of magnitude and also more rapidly star forming and dust obscured. While this demonstrates that GRBs populate all types of star-forming galaxies, including the most massive, luminous systems at z ≈ 2, at redshifts below 1.5 the overall GRB population continues to show a highly significant aversion to massive galaxies and a preference for low-mass systems relative to what would be expected given a purely star-formation-rate-selected galaxy sample. This supports the notion that the GRB rate is strongly dependent on metallicity, and may suggest that the most massive galaxies in the universe underwent a transition in their chemical properties ∼9 Gyr ago. We also conclude that, based on the absence of unobscured GRBs in massive galaxies and the absence of obscured GRBs in low-mass galaxies, the dust distributions of the lowest-mass and the highest-mass galaxies are relatively homogeneous, while intermediate-mass galaxies (∼10{sup 9} M {sub ☉}) have diverse internal properties.

  10. A massive dense gas cloud close to the nucleus of the Seyfert galaxy NGC 1068

    NASA Astrophysics Data System (ADS)

    Furuya, Ray S.; Taniguchi, Yoshiaki

    2016-12-01

    Using the ALMA archival data of both 12CO (6-5) line and 689-GHz continuum emission towards the archetypical Seyfert galaxy, NGC 1068, we identified a distinct continuum peak separated by 15 pc from the nuclear radio component S1 in projection. The continuum flux gives a gas mass of ˜2 × 105 M⊙ and bolometric luminosity of ˜108 L⊙, leading to a star formation rate of ˜0.1 M⊙ yr-1. Subsequent analysis on the line data suggest that the gas cloud has a size of ˜10 pc, yielding to a mean H2 number density of ˜105 cm-3. We therefore refer to the gas as a "massive dense gas cloud": the gas density is high enough to form a "protostar cluster" with a stellar mass of ˜104 M⊙. We found that the gas stands at a unique position between galactic and extraglactic clouds in the diagrams of start formation rate (SFR) vs. gas mass proposed by Lada et al. (2012, ApJ, 745, 190) and surface density of gas vs. SFR density by Krumholz and McKee (2005, ApJ, 630, 250). All the gaseous and star-formation properties may be understood in terms of the turbulence-regulated star formation scenario. Since there are two stellar populations with ages of 300 Myr and 30 Myr in the 100 pc scale circumnulear region, we discuss that NGC 1068 has experienced at least three episodic star-formation events with the likelihood that the inner star-forming region is the younger. Together with several lines of evidence that the dynamics of the nuclear region is decoupled from that of the entire galactic disk, we discuss that the gas inflow towards the nuclear region of NGC 1068 may be driven by a past minor merger.

  11. Embedded Spiral Patterns in the Cool Core of the Massive Cluster of Galaxies Abell 1835

    NASA Astrophysics Data System (ADS)

    Ueda, Shutaro; Kitayama, Tetsu; Dotani, Tadayasu

    2017-03-01

    We present the properties of an intracluster medium (ICM) in the cool core of the massive cluster of galaxies, Abell 1835, obtained with the data from the Chandra X-ray Observatory. We find distinctive spiral patterns with a radius of 70 kpc (or 18″) as a whole in the residual image of the X-ray surface brightness after the two-dimensional ellipse model of surface brightness is subtracted. The size is smaller by a factor of 2–4 than that of other clusters that are known to have a similar pattern. The spiral patterns consist of two arms. One of them appears as positive, and the other appears as negative excesses in the residual image. Their X-ray spectra show that the ICM temperatures in the positive- and negative-excess regions are {5.09}-0.13+0.12 keV and {6.52}-0.15+0.18 keV, respectively. In contrast, no significant difference is found in the abundance or pressure, the latter of which suggests that the ICM in the two regions of the spiral patterns is near or is in pressure equilibrium. The spatially resolved X-ray spectroscopy of the central region (r< 40\\prime\\prime ), divided into 92 sub-regions indicates that Abell 1835 is a typical cool core cluster. We also find that the spiral patterns extend from the cool core out to the hotter surrounding ICM. The residual image reveals some lumpy substructures in the cool core. The line of sight component of the disturbance velocity that is responsible for the substructures is estimated to be lower than 600 km s‑1. Abell 1835 may now be experiencing an off-axis minor merger.

  12. Building a better understanding of the massive high-redshift BOSS CMASS galaxies as tools for cosmology

    NASA Astrophysics Data System (ADS)

    Favole, Ginevra; McBride, Cameron K.; Eisenstein, Daniel J.; Prada, Francisco; Swanson, Molly E.; Chuang, Chia-Hsun; Schneider, Donald P.

    2016-10-01

    We explore the massive bluer star-forming population of the Sloan Digital Sky Survey (SDSS) III/BOSS CMASS DR11 galaxies at z > 0.55 to quantify their differences, in terms of redshift-space distortions and large-scale bias, with respect to the luminous red galaxy sample. We perform a qualitative analysis to understand the significance of these differences and whether we can model and reproduce them in mock catalogues. Specifically, we measure galaxy clustering in CMASS on small and intermediate scales (0.1 ≲ r ≲ 50 h-1 Mpc) by computing the two-point correlation function - both projected and redshift-space - of these galaxies, and a new statistic, Σ(π), able to separate the coherent and dispersed redshift-space distortion contributions and the large-scale bias. We interpret our clustering measurements by adopting a Halo Occupation Distribution (HOD) scheme that maps them on to high-resolution N-body cosmological simulations to produce suitable mock galaxy catalogues. The traditional HOD prescription can be applied to the red and the blue samples, independently, but this approach is unphysical since it allows the same mock galaxies to be either red or blue. To overcome this ambiguity, we modify the standard formulation and infer the red and the blue models by splitting the full mock catalogue into two complementary and non-overlapping submocks. This separation is performed by constraining the HOD with the observed CMASS red and blue galaxy fractions and produces reliable and accurate models.

  13. Constraining star formation and AGN in z ~ 2 massive galaxies using high-resolution MERLIN radio observations

    NASA Astrophysics Data System (ADS)

    Casey, C. M.; Chapman, S. C.; Muxlow, T. W. B.; Beswick, R. J.; Alexander, D. M.; Conselice, C. J.

    2009-05-01

    We present high spatial resolution Multi-Element Radio-Linked Interferometer Network (MERLIN) 1.4-GHz radio observations of two high-redshift (z ~ 2) sources, RGJ123623 (HDF147) and RGJ123617 (HDF130), selected as the brightest radio sources from a sample of submillimetre-faint radio galaxies. They have starburst classifications from their rest-frame ultraviolet spectra. However, their radio morphologies are remarkably compact (<80 and <65mas, respectively), demanding that the radio luminosity be dominated by active galactic nuclei (AGN) rather than starbursts. Near-infrared (IR) imaging [Hubble Space Telescope Near Infrared Camera and Multi-Object Spectrometer (NICMOS) F160W] shows large-scale sizes (R1/2 ~ 0.75arcsec, diameters ~12kpc) and spectral energy distribution (SED) fitting to photometric points (optical through the mid-IR) reveals massive (~5 × 1011Msolar), old (a few Gyr) stellar populations. Both sources have low flux densities at observed 24 μm and are undetected in observed 70 μm and 850 μm, suggesting a low mass of interstellar dust. They are also formally undetected in the ultradeep 2 Ms Chandra data, suggesting that any AGN activity is likely intrinsically weak. We suggest both galaxies have evolved stellar populations, low star formation rates and low accretion rates on to massive black holes (108.6Msolar) whose radio luminosity is weakly beamed (by factors of a few). A cluster-like environment has been identified near HDF130 by an overdensity of galaxies at z = 1.99, reinforcing the claim that clusters lead to more rapid evolution in galaxy populations. These observations suggest that high-resolution radio (MERLIN) can be a superb diagnostic tool of AGN in the diverse galaxy populations at z ~ 2.

  14. CANDELS: CORRELATIONS OF SPECTRAL ENERGY DISTRIBUTIONS AND MORPHOLOGIES WITH STAR FORMATION STATUS FOR MASSIVE GALAXIES AT z {approx} 2

    SciTech Connect

    Wang Tao; Gu Qiusheng; Huang Jiasheng; Fang Guanwen; Fazio, G. G.; Faber, S. M.; McGrath, Elizabeth J.; Kocevski, Dale; Yan Haojing; Dekel, Avishai; Guo Yicheng; Ferguson, Henry C.; Grogin, Norman; Lotz, Jennifer M.; Lucas, Ray A.; Koekemoer, A. M.; Weiner, Benjamin; Hathi, Nimish P.; Kong Xu

    2012-06-20

    We present a study on spectral energy distributions, morphologies, and star formation for an IRAC-selected extremely red object sample in the GOODS Chandra Deep Field-South. This work was enabled by new HST/WFC3 near-IR imaging from the CANDELS survey as well as the deepest available X-ray data from Chandra 4 Ms observations. This sample consists of 133 objects with the 3.6 {mu}m limiting magnitude of [3.6] = 21.5 and is approximately complete for galaxies with M{sub *} > 10{sup 11} M{sub Sun} at 1.5 {<=} z {<=} 2.5. We classify this sample into two types, quiescent and star-forming galaxies (SFGs), in the observed infrared color-color ([3.6]-[24] versus K - [3.6]) diagram. The further morphological study of this sample shows a consistent result with the observed color classification. The classified quiescent galaxies are bulge dominated and SFGs in the sample have disk or irregular morphologies. Our observed infrared color classification is also consistent with the rest-frame color (U - V versus V - J) classification. We also found that quiescent and SFGs are well separated in the nonparametric morphology parameter (Gini versus M{sub 20}) diagram measuring their concentration and clumpiness: quiescent galaxies have a Gini coefficient higher than 0.58 and SFGs have a Gini coefficient lower than 0.58. We argue that the star formation quenching process must lead to or be accompanied by the increasing galaxy concentration. One prominent morphological feature of this sample is that disks are commonly seen in this massive galaxy sample at 1.5 {<=} z {<=} 2.5: 30% of quiescent galaxies and 70% of SFGs with M{sub *} > 10{sup 11} M{sub Sun} have disks in their rest-frame optical morphologies. The prevalence of these extended, relatively undisturbed disks challenges the merging scenario as the main mode of massive galaxy formation.

  15. The VIPERS Multi-Lambda Survey. II. Diving with massive galaxies in 22 square degrees since z = 1.5

    NASA Astrophysics Data System (ADS)

    Moutard, T.; Arnouts, S.; Ilbert, O.; Coupon, J.; Davidzon, I.; Guzzo, L.; Hudelot, P.; McCracken, H. J.; Van Werbaeke, L.; Morrison, G. E.; Le Fèvre, O.; Comte, V.; Bolzonella, M.; Fritz, A.; Garilli, B.; Scodeggio, M.

    2016-05-01

    We investigate the evolution of the galaxy stellar mass function and stellar mass density from redshift z = 0.2 to z = 1.5 of a Ks < 22-selected sample with highly reliable photometric redshifts and over an unprecedentedly large area. Our study is based on near-infrared observations carried out with the WIRCam instrument at CFHT over the footprint of the VIPERS spectroscopic survey and benefits from the high-quality optical photometry from the CFHTLS and ultraviolet observations with the GALEX satellite. The accuracy of our photometric redshifts is σΔz/ (1 + z) < 0.03 and 0.05 for the bright (iAB< 22.5) and faint (iAB > 22.5) samples, respectively. The galaxy stellar mass function is measured with ~760 000 galaxies down to Ks ~ 22 and over an effective area of ~22.4 deg2, the latter of which drastically reduces the statistical uncertainties (i.e. Poissonian error and cosmic variance). We point out the importance of carefully controlling the photometric calibration, whose effect becomes quickly dominant when statistical uncertainties are reduced, which will be a major issue for future cosmological surveys with EUCLID or LSST, for instance. By exploring the rest-frame (NUV-r) vs. (r-Ks) colour-colour diagram with which we separated star-forming and quiescent galaxies, (1) we find that the density of very massive log (M∗/M⊙) > 11.5 galaxies is largely dominated by quiescent galaxies and increases by a factor 2 from z ~ 1 to z ~ 0.2, which allows for additional mass assembly through dry mergers. (2) We also confirm the scenario in which star formation activity is impeded above a stellar mass log(ℳ*SF/M⊙) = 10.64±0.01. This value is found to be very stable at 0.2 massive star-forming galaxies, and we finally (4) characterise another quenching mechanism that is required to explain the clear excess of low-mass quiescent galaxies that is observed at low redshift.

  16. The progenitors of local ultra-massive galaxies across cosmic time: from dusty star-bursting to quiescent stellar populations

    SciTech Connect

    Marchesini, Danilo; Marsan, Cemile Z.; Muzzin, Adam; Franx, Marijn; Stefanon, Mauro; Brammer, Gabriel G.; Vulcani, Benedetta; Fynbo, J. P. U.; Milvang-Jensen, Bo; Dunlop, James S.; Buitrago, Fernando

    2014-10-10

    Using the UltraVISTA catalogs, we investigate the evolution in the 11.4 Gyr since z = 3 of the progenitors of local ultra-massive galaxies (log (M {sub star}/M {sub ☉}) ≈ 11.8; UMGs), providing a complete and consistent picture of how the most massive galaxies at z = 0 have assembled. By selecting the progenitors with a semi-empirical approach using abundance matching, we infer a growth in stellar mass of 0.56{sub −0.25}{sup +0.35} dex, 0.45{sub −0.20}{sup +0.16} dex, and 0.27{sub −0.12}{sup +0.08} dex from z = 3, z = 2, and z = 1, respectively, to z = 0. At z < 1, the progenitors of UMGs constitute a homogeneous population of only quiescent galaxies with old stellar populations. At z > 1, the contribution from star-forming galaxies progressively increases, with the progenitors at 2 < z < 3 being dominated by massive (M {sub star} ≈ 2 × 10{sup 11} M {sub ☉}), dusty (A {sub V} ∼ 1-2.2 mag), star-forming (SFR ∼ 100-400 M {sub ☉} yr{sup –1}) galaxies with a large range in stellar ages. At z = 2.75, ∼15% of the progenitors are quiescent, with properties typical of post-starburst galaxies with little dust extinction and strong Balmer break, and showing a large scatter in color. Our findings indicate that at least half of the stellar content of local UMGs was assembled at z > 1, whereas the remaining was assembled via merging from z ∼ 1 to the present. Most of the quenching of the star-forming progenitors happened between z = 2.75 and z = 1.25, in good agreement with the typical formation redshift and scatter in age of z = 0 UMGs as derived from their fossil records. The progenitors of local UMGs, including the star-forming ones, never lived on the blue cloud since z = 3. We propose an alternative path for the formation of local UMGs that refines previously proposed pictures and that is fully consistent with our findings.

  17. THE IMPACT OF INTERACTIONS, BARS, BULGES, AND ACTIVE GALACTIC NUCLEI ON STAR FORMATION EFFICIENCY IN LOCAL MASSIVE GALAXIES

    SciTech Connect

    Saintonge, Amelie; Fabello, Silvia; Wang Jing; Catinella, Barbara; Tacconi, Linda J.; Genzel, Reinhard; Gracia-Carpio, Javier; Wuyts, Stijn; Kramer, Carsten; Moran, Sean; Heckman, Timothy M.; Schiminovich, David; Schuster, Karl

    2012-10-20

    Using atomic and molecular gas observations from the GASS and COLD GASS surveys and complementary optical/UV data from the Sloan Digital Sky Survey and the Galaxy Evolution Explorer, we investigate the nature of the variations in the molecular gas depletion time observed across the local massive galaxy population. The large and unbiased COLD GASS sample allows us for the first time to statistically assess the relative importance of galaxy interactions, bar instabilities, morphologies, and the presence of active galactic nuclei (AGNs) in regulating star formation efficiency. We find that both the H{sub 2} mass fraction and depletion time vary as a function of the distance of a galaxy from the main sequence traced by star-forming galaxies in the SFR-M {sub *} plane. The longest gas depletion times are found in below-main-sequence bulge-dominated galaxies ({mu}{sub *} >5 Multiplication-Sign 10{sup 8} M {sub Sun} kpc{sup -2}, C > 2.6) that are either gas-poor (M{sub H{sub 2}}/M {sub *} <1.5%) or else on average less efficient by a factor of {approx}2 than disk-dominated galaxies at converting into stars any cold gas they may have. We find no link between the presence of AGNs and these long depletion times. In the regime where galaxies are disk-dominated and gas-rich, the galaxies undergoing mergers or showing signs of morphological disruptions have the shortest molecular gas depletion times, while those hosting strong stellar bars have only marginally higher global star formation efficiencies as compared to matched control samples. Our interpretation is that the molecular gas depletion time variations are caused by changes in the ratio between the gas mass traced by the CO(1-0) observations and the gas mass in high-density star-forming cores (as traced by observations of, e.g., HCN(1-0)). While interactions, mergers, and bar instabilities can locally increase pressure and raise the ratio of efficiently star-forming gas to CO-detected gas (therefore lowering the CO

  18. Galaxy and Mass Assembly (GAMA): Selection of the Most Massive Clusters

    NASA Astrophysics Data System (ADS)

    Ibarra-Medel, Héctor J.; Lara-López, Maritza; López-Cruz, Omar

    2016-10-01

    We have developed a galaxy cluster finding technique based on the Delaunay Tessellation Field Estimator (DTFE) combined with caustic analysis. Our method allows us to recover clusters of galaxies within the mass range of $1012$ to $1016\\ \\mathcal{M}\\odot$. We have found a total of 113 galaxy clusters in the Galaxy and Mass Assembly survey (GAMA). In the corresponding mass range, the density of clusters found in this work is comparable to the density traced by clusters selected by the thermal Sunyaev Zel'dovich Effect; however, we are able to cover a wider mass range. We present the analysis of the two-point correlation function for our cluster sample.

  19. Merger-driven evolution of the effective stellar initial mass function of massive early-type galaxies

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Alessandro; Nipoti, Carlo; Treu, Tommaso

    2017-02-01

    The stellar initial mass function (IMF) of early-type galaxies is the combination of the IMF of the stellar population formed in situ and that of accreted stellar populations. Using as an observable the effective IMF αIMF, defined as the ratio between the true stellar mass of a galaxy and the stellar mass inferred assuming a Salpeter IMF, we present a theoretical model for its evolution as a result of dry mergers. We use a simple dry-merger evolution model, based on cosmological N-body simulations, together with empirically motivated prescriptions for the IMF to make predictions on how the effective IMF of massive early-type galaxies changes from z = 2 to z = 0. We find that the IMF normalization of individual galaxies becomes lighter with time. At fixed velocity dispersion, αIMF is predicted to be constant with redshift. Current dynamical constraints on the evolution of the IMF are in slight tension with this prediction, even though systematic uncertainties, including the effect of radial gradients in the IMF, prevent a conclusive statement. The correlation of αIMF with stellar mass becomes shallower with time, while the correlation between αIMF and velocity dispersion is mostly preserved by dry mergers. We also find that dry mergers can mix the dependence of the IMF on stellar mass and velocity dispersion, making it challenging to infer, from z = 0 observations of global galactic properties, what is the quantity that is originally coupled with the IMF.

  20. Gas-to-dust ratios in massive star-forming galaxies at z ˜ 1.4

    NASA Astrophysics Data System (ADS)

    Seko, Akifumi; Ohta, Kouji; Yabe, Kiyoto; Hatsukade, Bunyo; Aono, Yuya; Iono, Daisuke

    2016-08-01

    We present results of 12CO(J = 2-1) observations toward four massive star-forming galaxies at z ˜ 1.4 with the Nobeyama 45 m radio telescope. The galaxies are detected with Spitzer/MIPS in 24 μm and Herschel/SPIRE in 250 μm and 350 μm, and they mostly reside in the main sequence. Their gas-phase metallicities derived by the N2 method using the Hα and [N II]λ 6584 emission lines are near the solar value. CO lines are detected toward three galaxies. The molecular-gas masses obtained are (9.6-35) × 1010 M⊙ by adopting the Galactic CO-to-H2 conversion factor and a CO(2-1)/CO(1-0) flux ratio of 3. The dust masses derived from the modified blackbody model (assuming a dust temperature of 35 K and an emissivity index of 1.5) are (2.4-5.4) × 108 M⊙. Resulting gas-to-dust ratios (not accounting for H I mass) at z ˜ 1.4 are 220-1450, which are several times larger than those in local star-forming galaxies. A dependence of the gas-to-dust ratio on the far-infrared luminosity density is not clearly seen.

  1. IDCS J1426.5+3508: DISCOVERY OF A MASSIVE, INFRARED-SELECTED GALAXY CLUSTER AT z = 1.75

    SciTech Connect

    Stanford, S. A.; Zeimann, Greg; Brodwin, M.; Gonzalez, Anthony H.; Mancone, C.; Stern, Daniel; Eisenhardt, P. R.; Dey, Arjun; Snyder, Gregory F.

    2012-07-10

    We report the discovery of an IR-selected massive galaxy cluster in the IRAC Deep Cluster Survey (IDCS). We present new data from the Hubble Space Telescope and the W. M. Keck Observatory that spectroscopically confirm IDCS J1426.5+3508 at z = 1.75. Moreover, the cluster is detected in archival Chandra data as an extended X-ray source, comprising 53 counts after the removal of point sources. We calculate an X-ray luminosity of L{sub 0.5-2keV} = (5.4 {+-} 1.2) Multiplication-Sign 10{sup 44} erg s{sup -1} within r = 60 arcsec ({approx}1 Mpc diameter), which implies M{sub 200,L{sub x}}= (5.3{+-}1.6) Multiplication-Sign 10{sup 14} M{sub Sun }. IDCS J1426.5+3508 appears to be an exceptionally massive cluster for its redshift.

  2. Cosmology with massive neutrinos I: towards a realistic modeling of the relation between matter, haloes and galaxies

    SciTech Connect

    Villaescusa-Navarro, Francisco; Viel, Matteo; Marulli, Federico; Castorina, Emanuele; Sefusatti, Emiliano; Saito, Shun E-mail: federico.marulli3@unibo.it E-mail: branchin@fis.uniroma3.it E-mail: esefusat@ictp.it

    2014-03-01

    By using a suite of large box-size N-body simulations that incorporate massive neutrinos as an extra set of particles, with total masses of 0.15, 0.30, and 0.60 eV, we investigate the impact of neutrino masses on the spatial distribution of dark matter haloes and on the distribution of galaxies within the haloes. We compute the bias between the spatial distribution of dark matter haloes and the overall matter and cold dark matter distributions using statistical tools such as the power spectrum and the two-point correlation function. Overall we find a scale-dependent bias on large scales for the cosmologies with massive neutrinos. In particular, we find that the bias decreases with the scale, being this effect more important for higher neutrino masses and at high redshift. However, our results indicate that the scale-dependence in the bias is reduced if the latter is computed with respect to the cold dark matter distribution only. We find that the value of the bias on large scales is reasonably well reproduced by the Tinker fitting formula once the linear cold dark matter power spectrum is used, instead of the total matter power spectrum. We also investigate whether scale-dependent bias really comes from purely neutrino's effect or from nonlinear gravitational collapse of haloes. For this purpose, we address the Ω{sub ν}-σ{sub 8} degeneracy and find that such degeneracy is not perfect, implying that neutrinos imprint a slight scale dependence on the large-scale bias. Finally, by using a simple halo occupation distribution (HOD) model, we investigate the impact of massive neutrinos on the distribution of galaxies within dark matter haloes. We use the main galaxy sample in the Sloan Digital Sky Survey (SDSS) II Data Release 7 to investigate if the small-scale galaxy clustering alone can be used to discriminate among different cosmological models with different neutrino masses. Our results suggest that different choices of the HOD parameters can reproduce the

  3. The distribution of satellites around massive galaxies at 1 < z < 3 in ZFOURGE/CANDELS: Dependence on star formation activity

    SciTech Connect

    Kawinwanichakij, Lalitwadee; Papovich, Casey; Quadri, Ryan F.; Tran, Kim-Vy H.; Mehrtens, Nicola; Spitler, Lee R.; Cowley, Michael; Kacprzak, Glenn G.; Glazebrook, Karl; Nanayakkara, Themiya; Labbé, Ivo; Straatman, Caroline M. S.; Allen, Rebecca; Davé, Romeel; Dekel, Avishai; Ferguson, Henry C.; Koekemoer, Anton M.; Hartley, W. G.; Koo, David C.; and others

    2014-09-10

    We study the statistical distribution of satellites around star-forming and quiescent central galaxies at 1 < z < 3 using imaging from the FourStar Galaxy Evolution Survey and the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey. The deep near-IR data select satellites down to log (M/M {sub ☉}) > 9 at z < 3. The radial satellite distribution around centrals is consistent with a projected Navarro-Frenk-White profile. Massive quiescent centrals, log (M/M {sub ☉}) > 10.78, have ∼2 times the number of satellites compared to star-forming centrals with a significance of 2.7σ even after accounting for differences in the centrals' stellar-mass distributions. We find no statistical difference in the satellite distributions of intermediate-mass quiescent and star-forming centrals, 10.48 < log (M/M {sub ☉}) < 10.78. Compared to the Guo et al. semi-analytic model, the excess number of satellites indicates that quiescent centrals have halo masses 0.3 dex larger than star-forming centrals, even when the stellar-mass distributions are fixed. We use a simple toy model that relates halo mass and quenching, which roughly reproduces the observed quenched fractions and the differences in halo mass between star-forming and quenched galaxies only if galaxies have a quenching probability that increases with halo mass from ∼0 for log (M{sub h} /M {sub ☉}) ∼ 11 to ∼1 for log (M{sub h} /M {sub ☉}) ∼ 13.5. A single halo-mass quenching threshold is unable to reproduce the quiescent fraction and satellite distribution of centrals. Therefore, while halo quenching may be an important mechanism, it is unlikely to be the only factor driving quenching. It remains unclear why a high fraction of centrals remain star-forming even in relatively massive halos.

  4. The inner structure of very massive elliptical galaxies: implications for the inside-out formation mechanism of z˜ 2 galaxies

    NASA Astrophysics Data System (ADS)

    Tiret, O.; Salucci, P.; Bernardi, M.; Maraston, C.; Pforr, J.

    2011-03-01

    We analyse a sample of 23 supermassive elliptical galaxies (central velocity dispersion larger than 330 km s-1) drawn from the Sloan Digital Sky Survey. For each object, we estimate the dynamical mass from the light profile and central velocity dispersion, and compare it with the stellar mass derived from stellar population models. We show that these galaxies are dominated by luminous matter within the radius for which the velocity dispersion is measured. We find that the sizes and stellar masses are tightly correlated, with Re∝M1.1*, making the mean density within the de Vaucouleurs radius a steeply declining function of M*: ρe∝M-2.2*. These scalings are easily derived from the virial theorem if one recalls that this sample has essentially fixed (but large) σ0. In contrast, the mean density within 1 kpc is almost independent of M*, at a value that is in good agreement with recent studies of z˜ 2 galaxies. The fact that the mass within 1 kpc has remained approximately unchanged suggests assembly histories that were dominated by minor mergers - but we discuss why this is not the unique way to achieve this. Moreover, the total stellar mass of the objects in our sample is typically a factor of ˜5 larger than that in the high-redshift (z˜ 2) sample, an amount which seems difficult to achieve. If our galaxies are the evolved objects of the recent high-redshift studies, then we suggest that major mergers are required at z≳ 1.5 and that minor mergers become the dominant growth mechanism for massive galaxies at z≲ 1.5.

  5. Galaxy clustering, CMB and supernova data constraints on ϕCDM model with massive neutrinos

    NASA Astrophysics Data System (ADS)

    Chen, Yun; Xu, Lixin

    2016-01-01

    We investigate a scalar field dark energy model (i.e., ϕCDM model) with massive neutrinos, where the scalar field possesses an inverse power-law potential, i.e., V (ϕ) ∝ϕ-α (α > 0). We find that the sum of neutrino masses Σmν has significant impacts on the CMB temperature power spectrum and on the matter power spectrum. In addition, the parameter α also has slight impacts on the spectra. A joint sample, including CMB data from Planck 2013 and WMAP9, galaxy clustering data from WiggleZ and BOSS DR11, and JLA compilation of Type Ia supernova observations, is adopted to confine the parameters. Within the context of the ϕCDM model under consideration, the joint sample determines the cosmological parameters to high precision: the angular size of the sound horizon at recombination, the Thomson scattering optical depth due to reionization, the physical densities of baryons and cold dark matter, and the scalar spectral index are estimated to be θ* = (1.0415-0.0011+0.0012) ×10-2, τ =0.0914-0.0242+0.0266, Ωbh2 = 0.0222 ± 0.0005, Ωch2 = 0.1177 ± 0.0036, and ns =0.9644-0.0119+0.0118, respectively, at 95% confidence level (CL). It turns out that α < 4.995 at 95% CL for the ϕCDM model. And yet, the ΛCDM scenario corresponding to α = 0 is not ruled out at 95% CL. Moreover, we get Σmν < 0.262 eV at 95% CL for the ϕCDM model, while the corresponding one for the ΛCDM model is Σmν < 0.293 eV. The allowed scale of Σmν in the ϕCDM model is a bit smaller than that in the ΛCDM model. It is consistent with the qualitative analysis, which reveals that the increases of α and Σmν both can result in the suppression of the matter power spectrum. As a consequence, when α is larger, in order to avoid suppressing the matter power spectrum too much, the value of Σmν should be smaller.

  6. RELICS OF GALAXY MERGING: OBSERVATIONAL PREDICTIONS FOR A WANDERING MASSIVE BLACK HOLE AND ACCOMPANYING STAR CLUSTER IN THE HALO OF M31

    SciTech Connect

    Kawaguchi, Toshihiro; Saito, Yuriko; Miki, Yohei; Mori, Masao

    2014-07-01

    Galaxies and massive black holes (BHs) presumably grow via galactic merging events and subsequent BH coalescence. As a case study, we investigate the merging event between the Andromeda galaxy (M31) and a satellite galaxy. We compute the expected observational appearance of the massive BH that was at the center of the satellite galaxy prior to the merger and is currently wandering in the M31 halo. We demonstrate that a radiatively inefficient accretion flow with a bolometric luminosity of a few tens of solar luminosities develops when Hoyle-Lyttleton accretion onto the BH is assumed. We compute the associated broadband spectrum and show that the radio band (observable with EVLA, ALMA, and the Square Kilometre Array) is the best frequency range in which to detect the emission. We also evaluate the mass and the luminosity of the stars bound by the wandering BH and find that such a star cluster is sufficiently luminous that it could correspond to one of the star clusters found by the PAndAS survey. The discovery of a relic massive BH wandering in a galactic halo will provide a direct means of investigating in detail the coevolution of galaxies and BHs. It also means a new population of BHs (off-center massive BHs) and offers targets for clean BH imaging that avoid strong interstellar scattering in the centers of galaxies.

  7. Study of the growth of massive galaxies based on their outer stellar populations

    NASA Astrophysics Data System (ADS)

    Karabal, Emin

    2017-03-01

    The outskirts of early-type galaxies (ETGs) play a key role to shed light on the mass assembly of galaxies. Deep imaging has become one of the main tools to study these regions, however artificial halos caused by bright sources hampers the photometric analysis. To get around the problem, extended PSFs are built and deconvolution is performed on images.

  8. SImulator of GAlaxy Millimetre/submillimetre Emission (SÍGAME): CO emission from massive z = 2 main-sequence galaxies

    NASA Astrophysics Data System (ADS)

    Olsen, Karen P.; Greve, Thomas R.; Brinch, Christian; Sommer-Larsen, Jesper; Rasmussen, Jesper; Toft, Sune; Zirm, Andrew

    2016-04-01

    We present SÍGAME (SImulator of GAlaxy Millimetre/submillimetre Emission), a new numerical code designed to simulate the 12CO rotational line spectrum of galaxies. Using sub-grid physics recipes to post-process the outputs of smoothed particle hydrodynamics (SPH) simulations, a molecular gas phase is condensed out of the hot and partly ionized SPH gas. The gas is subjected to far-UV radiation fields and cosmic ray ionization rates which are set to scale with the local star formation rate volume density. Level populations and radiative transport of the CO lines are solved with the 3D radiative transfer code LIME. We have applied SÍGAME to cosmological SPH simulations of three disc galaxies at z = 2 with stellar masses in the range ˜0.5-2 × 1011 M⊙ and star formation rates ˜40-140 M⊙ yr-1. Global CO luminosities and line ratios are in agreement with observations of disc galaxies at z ˜ 2 up to and including J = 3-2 but falling short of the few existing J=5-4 observations. The central 5 kpc regions of our galaxies have CO 3 - 2/1 - 0 and 7 - 6/1 - 0 brightness temperature ratios of ˜0.55-0.65 and ˜0.02-0.08, respectively, while further out in the disc the ratios drop to more quiescent values of ˜0.5 and <0.01. Global CO-to-H2 conversion (αCO) factors are {˜eq } 1.5 {{M_{⊙}} pc^{-2} (K km s^{-1})^{-1}}, i.e. ˜2-3 times below the typically adopted values for disc galaxies, and αCO increases with radius, in agreement with observations of nearby galaxies. Adopting a top-heavy Giant Molecular Cloud (GMC) mass spectrum does not significantly change the results. Steepening the GMC density profiles leads to higher global line ratios for Jup ≥ 3 and CO-to-H2 conversion factors [{˜eq } 3.6 {{M_{⊙}} pc^{-2} (K km s^{-1})^{-1}}].

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

    DOE PAGES

    Tenneti, Ananth; Singh, Sukhdeep; Mandelbaum, Rachel; ...

    2015-03-11

    The intrinsic alignment of galaxies with the large-scale density field in an important astrophysical contaminant in upcoming weak lensing surveys. We present detailed measurements of the galaxy intrinsic alignments and associated ellipticity-direction (ED) and projected shape (wg₊) correlation functions for galaxies in the cosmological hydrodynamic MassiveBlack-II (MB-II) simulation. We carefully assess the effects on galaxy shapes, misalignment of the stellar component with the dark matter shape and two-point statistics of iterative weighted (by mass and luminosity) definitions of the (reduced and unreduced) inertia tensor. We find that iterative procedures must be adopted for a reliable measurement of the reduced tensormore » but that luminosity versus mass weighting has only negligible effects. Both ED and wg₊ correlations increase in amplitude with subhalo mass (in the range of 10¹⁰ – 6.0 X 10¹⁴h⁻¹ M⊙), with a weak redshift dependence (from z = 1 to z = 0.06) at fixed mass. At z ~ 0.3, we predict a wg₊ that is in reasonable agreement with SDSS LRG measurements and that decreases in amplitude by a factor of ~ 5–18 for galaxies in the LSST survey. We also compared the intrinsic alignment of centrals and satellites, with clear detection of satellite radial alignments within the host halos. Finally, we show that wg₊ (using subhalos as tracers of density and wδ (using dark matter density) predictions from the simulations agree with that of non-linear alignment models (NLA) at scales where the 2-halo term dominates in the correlations (and tabulate associated NLA fitting parameters). The 1-halo term induces a scale dependent bias at small scales which is not modeled in the NLA model.« less

  10. Intrinsic alignments of galaxies in the MassiveBlack-II simulation: Analysis of two-point statistics

    SciTech Connect

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

    2015-03-11

    The intrinsic alignment of galaxies with the large-scale density field in an important astrophysical contaminant in upcoming weak lensing surveys. We present detailed measurements of the galaxy intrinsic alignments and associated ellipticity-direction (ED) and projected shape (wg₊) correlation functions for galaxies in the cosmological hydrodynamic MassiveBlack-II (MB-II) simulation. We carefully assess the effects on galaxy shapes, misalignment of the stellar component with the dark matter shape and two-point statistics of iterative weighted (by mass and luminosity) definitions of the (reduced and unreduced) inertia tensor. We find that iterative procedures must be adopted for a reliable measurement of the reduced tensor but that luminosity versus mass weighting has only negligible effects. Both ED and wg₊ correlations increase in amplitude with subhalo mass (in the range of 10¹⁰ – 6.0 X 10¹⁴h⁻¹ M), with a weak redshift dependence (from z = 1 to z = 0.06) at fixed mass. At z ~ 0.3, we predict a wg₊ that is in reasonable agreement with SDSS LRG measurements and that decreases in amplitude by a factor of ~ 5–18 for galaxies in the LSST survey. We also compared the intrinsic alignment of centrals and satellites, with clear detection of satellite radial alignments within the host halos. Finally, we show that wg₊ (using subhalos as tracers of density and wδ (using dark matter density) predictions from the simulations agree with that of non-linear alignment models (NLA) at scales where the 2-halo term dominates in the correlations (and tabulate associated NLA fitting parameters). The 1-halo term induces a scale dependent bias at small scales which is not modeled in the NLA model.

  11. ONE PLANE FOR ALL: MASSIVE STAR-FORMING AND QUIESCENT GALAXIES LIE ON THE SAME MASS FUNDAMENTAL PLANE AT z ∼ 0 AND z ∼ 0.7

    SciTech Connect

    Bezanson, Rachel; Franx, Marijn; Van Dokkum, Pieter G.

    2015-02-01

    Scaling relations between galaxy structures and dynamics have been studied extensively for early- and late-type galaxies, both in the local universe and at high redshifts. The abundant differences between the properties of disky and elliptical, or star-forming and quiescent, galaxies seem to be characteristic of the local universe; such clear distinctions begin to disintegrate as observations of massive galaxies probe higher redshifts. In this paper we investigate the existence of the mass fundamental plane of all massive galaxies (σ ≳ 100 km s{sup –1}). This work includes local galaxies (0.05 < z < 0.07) from the Sloan Digital Sky Survey, in addition to 31 star-forming and 72 quiescent massive galaxies at intermediate redshift (z ∼ 0.7) with absorption-line kinematics from deep Keck-DEIMOS spectra and structural parameters from Hubble Space Telescope imaging. In two-parameter scaling relations, star-forming and quiescent galaxies differ structurally and dynamically. However, we show that massive star-forming and quiescent galaxies lie on nearly the same mass fundamental plane, or the relationship between stellar mass surface density, stellar velocity dispersion, and effective radius. The scatter in this relation (measured about log σ) is low: 0.072 dex (0.055 dex intrinsic) at z ∼ 0 and 0.10 dex (0.08 dex intrinsic) at z ∼ 0.7. This 3D surface is not unique: virial relations, with or without a dependence on luminosity profile shapes, can connect galaxy structures and stellar dynamics with similar scatter. This result builds on the recent finding that mass fundamental plane has been stable for early-type galaxies since z ∼ 2. As we now find that this also holds for star-forming galaxies to z ∼ 0.7, this implies that these scaling relations of galaxies will be minimally susceptible to progenitor biases owing to the evolving stellar populations, structures, and dynamics of galaxies through cosmic time.

  12. MASSIVE CLUMPS IN LOCAL GALAXIES: COMPARISONS WITH HIGH-REDSHIFT CLUMPS

    SciTech Connect

    Elmegreen, Bruce G.; Elmegreen, Debra Meloy; Dewberry, J.; Putko, J.; Teich, Y.; Popinchalk, M.; Sanchez Almeida, J.; Munoz-Tunon, C.

    2013-09-01

    Local UV-bright galaxies in the Kiso survey include clumpy systems with kiloparsec-size star complexes that resemble clumpy young galaxies in surveys at high redshift. We compare clump masses and underlying disks in several dozen galaxies from each of these surveys to the star complexes and disks of normal spirals. Photometry and spectroscopy for the Kiso and spiral sample come from the Sloan Digital Sky Survey. We find that the largest Kiso clumpy galaxies resemble Ultra Deep Field (UDF) clumpies in terms of the star formation rates, clump masses, and clump surface densities. Clump masses and surface densities in normal spirals are smaller. If the clump masses are proportional to the turbulent Jeans mass in the interstellar medium, then for the most luminous galaxies in the sequence of normal:Kiso:UDF, the turbulent speeds and surface densities increase in the proportions 1.0:4.7:5.0 and 1.0:4.0:5.1, respectively, for fixed restframe B-band absolute magnitude. For the least luminous galaxies in the overlapping magnitude range, the turbulent speed and surface density trends are 1.0:2.7:7.4 and 1.0:1.4:3.0, respectively. We also find that while all three types have radially decreasing disk intensities when measured with ellipse-fit azimuthal averages, the average profiles are more irregular for UDF clumpies (which are viewed in their restframe UV) than for Kiso galaxies (viewed at g-band), and major axis intensity scans are even more irregular for the UDF than Kiso galaxies. Local clumpy galaxies in the Kiso survey appear to be intermediate between UDF clumpies and normal spirals.

  13. DISCOVERY OF MASSIVE, MOSTLY STAR FORMATION QUENCHED GALAXIES WITH EXTREMELY LARGE Lyα EQUIVALENT WIDTHS AT z ∼ 3

    SciTech Connect

    Taniguchi, Yoshiaki; Kajisawa, Masaru; Kobayashi, Masakazu A. R.; Nagao, Tohru; Shioya, Yasuhiro; Scoville, Nick Z.; Capak, Peter L.; Sanders, David B.; Koekemoer, Anton M.; Toft, Sune; McCracken, Henry J.; Le Fèvre, Olivier; Tasca, Lidia; Ilbert, Olivier; Sheth, Kartik; Renzini, Alvio; Lilly, Simon; Carollo, Marcella; Kovač, Katarina; Schinnerer, Eva; and others

    2015-08-10

    We report a discovery of six massive galaxies with both extremely large Lyα equivalent widths (EWs) and evolved stellar populations at z ∼ 3. These MAssive Extremely STrong Lyα emitting Objects (MAESTLOs) have been discovered in our large-volume systematic survey for strong Lyα emitters (LAEs) with 12 optical intermediate-band data taken with Subaru/Suprime-Cam in the COSMOS field. Based on the spectral energy distribution fitting analysis for these LAEs, it is found that these MAESTLOs have (1) large rest-frame EWs of EW{sub 0} (Lyα) ∼ 100–300 Å, (2) M{sub ⋆} ∼ 10{sup 10.5}–10{sup 11.1} M{sub ⊙}, and (3) relatively low specific star formation rates of SFR/M{sub ⋆} ∼ 0.03–1 Gyr{sup −1}. Three of the six MAESTLOs have extended Lyα emission with a radius of several kiloparsecs, although they show very compact morphology in the HST/ACS images, which correspond to the rest-frame UV continuum. Since the MAESTLOs do not show any evidence for active galactic nuclei, the observed extended Lyα emission is likely to be caused by a star formation process including the superwind activity. We suggest that this new class of LAEs, MAESTLOs, provides a missing link from star-forming to passively evolving galaxies at the peak era of the cosmic star formation history.

  14. PRECISE IDENTIFICATIONS OF SUBMILLIMETER GALAXIES: MEASURING THE HISTORY OF MASSIVE STAR-FORMING GALAXIES TO z > 5 {sup ,} {sup ,}

    SciTech Connect

    Barger, A. J.; Wang, W.-H.; Cowie, L. L.; Chen, C.-C.; Williams, J. P.; Owen, F. N.

    2012-12-20

    We carried out extremely sensitive Submillimeter Array (SMA) 340 GHz (860 {mu}m) continuum imaging of a complete sample of SCUBA 850 {mu}m sources (>4{sigma}) with fluxes >3 mJy in the GOODS-N. Using these data and new SCUBA-2 data, we do not detect 4 of the 16 SCUBA sources, and we rule out the original SCUBA fluxes at the 4{sigma} level. Three more resolve into multiple fainter SMA galaxies, suggesting that our understanding of the most luminous high-redshift dusty galaxies may not be as reliable as we thought. 10 of the 16 independent SMA sources have spectroscopic redshifts (optical/infrared or CO) up to z = 5.18. Using a new, ultradeep 20 cm image obtained with the Karl G. Jansky Very Large Array (rms of 2.5 {mu}Jy), we find that all 16 of the SMA sources are detected at >5{sigma}. Using Herschel far-infrared (FIR) data, we show that the five isolated SMA sources with Herschel detections are well described by an Arp 220 spectral energy distribution template in the FIR. They also closely obey the local FIR-radio correlation, a result that does not suffer from a radio bias. We compute the contribution from the 16 SMA sources to the universal star formation rate (SFR) per comoving volume. With individual SFRs in the range 700-5000 M{sub Sun} yr{sup -1}, they contribute {approx}30% of the extinction-corrected ultraviolet-selected SFR density from z = 1 to at least z = 5. Star formation histories determined from extinction-corrected ultraviolet populations and from submillimeter galaxy populations only partially overlap, due to the extreme ultraviolet faintness of some submillimeter galaxies.

  15. Isophote Shapes of Early-type Galaxies in Massive Clusters at z ∼ 1 and 0

    NASA Astrophysics Data System (ADS)

    Mitsuda, Kazuma; Doi, Mamoru; Morokuma, Tomoki; Suzuki, Nao; Yasuda, Naoki; Perlmutter, Saul; Aldering, Greg; Meyers, Joshua

    2017-01-01

    We compare the isophote shape parameter a4 of early-type galaxies (ETGs) between z ∼ 1 and 0 as a proxy for dynamics to investigate the epoch at which the dynamical properties of ETGs are established, using cluster ETG samples with stellar masses of {log}({M}* /{M}ȯ )≥slant 10.5 which have spectroscopic redshifts. We have 130 ETGs from the Hubble Space Telescope Cluster Supernova Survey for z ∼ 1 and 355 ETGs from the Sloan Digital Sky Survey for z ∼ 0. We have developed an isophote shape analysis method, which can be used for high-redshift galaxies and has been carefully compared with published results. We have applied the same method for both the z ∼ 1 and 0 samples. We find similar dependence of the a4 parameter on the mass and size at z ∼ 1 and 0; the main population of ETGs changes from disky to boxy at a critical stellar mass of {log}({M}* /{M}ȯ )∼ 11.5 with the massive end dominated by boxy. The disky ETG fraction decreases with increasing stellar mass both at z ∼ 1 and 0, and is consistent between these redshifts in all stellar mass bins when the Eddington bias is taken into account. Although uncertainties are large, the results suggest that the isophote shapes and probably dynamical properties of ETGs in massive clusters are already in place at z > 1 and do not significantly evolve in z < 1, despite significant size evolution in the same galaxy population. The constant disky fraction favors less violent processes than mergers as the main cause of the size and morphological evolution of intermediate mass ETGs in z < 1.

  16. SALPETER NORMALIZATION OF THE STELLAR INITIAL MASS FUNCTION FOR MASSIVE GALAXIES AT z ∼ 1

    SciTech Connect

    Shetty, Shravan; Cappellari, Michele

    2014-05-10

    The stellar initial mass function (IMF) is a key parameter for studying galaxy evolution. Here we measure the IMF mass normalization for a sample of 68 field galaxies in the redshift range 0.7-0.9 within the Extended Groth Strip. To do this we derive the total (stellar + dark matter) mass-to-light [(M/L)] ratio using axisymmetric dynamical models. Within the region where we have kinematics (about one half-light radius), the models assume (1) that mass follows light, implying negligible differences between the slope of the stellar and total density profiles, (2) constant velocity anisotropy (β{sub z}≡1−σ{sub z}{sup 2}/σ{sub R}{sup 2}=0.2), and (3) that galaxies are seen at the average inclination for random orientations (i.e., i = 60°, where i = 90° represents edge-on). The dynamical models are based on anisotropic Jeans equations, constrained by Hubble Space Telescope/Advanced Camera for Surveys imaging and the central velocity dispersion of the galaxies, extracted from good-quality spectra taken by the DEEP2 survey. The population (M/L) are derived from full-spectrum fitting of the same spectra with a grid of simple stellar population models. Recent dynamical modeling results from the ATLAS{sup 3D} project and numerical simulations of galaxy evolution indicate that the dark matter fraction within the central regions of our galaxies should be small. This suggests that our derived total (M/L) should closely approximate the stellar M/L. Our comparison of the dynamical (M/L) and the population (M/L) then implies that for galaxies with stellar mass M {sub *} ≳ 10{sup 11} M {sub ☉}, the average normalization of the IMF is consistent with a Salpeter slope, with a substantial scatter. This is similar to what is found within a similar mass range for nearby galaxies.

  17. Weak Lensing with the Hyper Suprime-Cam Survey: Connecting the Mass Profiles of Massive Galaxies with their Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Leauthaud, Alexie; HSC Survey Collaboration

    2017-01-01

    The HSC survey is an ambitious multi-wavelength (g,r,i,z,y) weak-lensing program to map out 1400 square degrees of the sky with the 8.2m Subaru Telescope to a 5 sigma point-source depth of i~26 mag. This is a truly unique combination of deep imaging over a wide area which makes this a well suited data-set for studying the mass profiles and assembly histories of the most rare and massive galaxies in the universe. Furthermore, the lensing capabilities of HSC means that we can tie the luminous properties of massive galaxies to the properties of their dark matter halos. With 240 deg^2 of excellent quality imaging data already in hand, I will show that HSC can simultaneously map the light profiles of massive galaxies out to 100 kpc and characterize the profiles of their host dark matter halos to radii greater than 10 Mpc. By comparing with modern hydrodynamic simulations of galaxy formation, I will show that the combination of these two measurements provides strong observational constraints on the strength of feedback mechanisms in massive galaxies.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. THE STELLAR MASS STRUCTURE OF MASSIVE GALAXIES FROM z = 0 TO z = 2.5: SURFACE DENSITY PROFILES AND HALF-MASS RADII

    SciTech Connect

    Szomoru, Daniel; Franx, Marijn; Labbe, Ivo; Van Dokkum, Pieter G.; Trenti, Michele; Illingworth, Garth D.; Oesch, Pascal

    2013-02-15

    We present stellar mass surface density profiles of a mass-selected sample of 177 galaxies at 0.5 < z < 2.5, obtained using very deep Hubble Space Telescope optical and near-infrared data over the GOODS-South field, including recent CANDELS data. Accurate stellar mass surface density profiles have been measured for the first time for a complete sample of high-redshift galaxies more massive than 10{sup 10.7} M {sub Sun }. The key advantage of this study compared to previous work is that the surface brightness profiles are deconvolved for point-spread function smoothing, allowing accurate measurements of the structure of the galaxies. The surface brightness profiles account for contributions from complex galaxy structures such as rings and faint outer disks. Mass profiles are derived using radial rest-frame ug color profiles and a well-established empirical relation between these colors and the stellar mass-to-light ratio. We derive stellar half-mass radii from the mass profiles, and find that these are on average {approx}25% smaller than rest-frame g-band half-light radii. This average size difference of 25% is the same at all redshifts, and does not correlate with stellar mass, specific star formation rate, effective surface density, Sersic index, or galaxy size. Although on average the difference between half-mass size and half-light size is modest, for approximately 10% of massive galaxies this difference is more than a factor of two. These extreme galaxies are mostly extended, disk-like systems with large central bulges. These results are robust, but could be impacted if the central dust extinction becomes high. ALMA observations can be used to explore this possibility. These results provide added support for galaxy growth scenarios wherein massive galaxies at these epochs grow by accretion onto their outer regions.

  20. Observations of Lyα and O vi: Signatures of Cooling and Star Formation in a Massive Central Cluster Galaxy

    NASA Astrophysics Data System (ADS)

    Donahue, Megan; Connor, Thomas; Voit, G. Mark; Postman, Marc

    2017-02-01

    We report new Hubble Space Telescope COS and Space Telescope Imaging Spectrograph spectroscopy of a star-forming region (∼ 100 {M}ȯ yr‑1) in the center of the X-ray cluster RX J1532.9+3021 (z = 0.362), to follow-up the CLASH team discovery of luminous UV filaments and knots in the central massive galaxy. We detect broad (∼500 km s‑1) Lyα emission lines with extraordinarily high equivalent widths (EQW ∼ 200 Å) and somewhat less broadened Hα (∼220 km s‑1). Ultraviolet emission lines of N v and O vi are not detected, which constrains the rate at which gas cools through temperatures of 106 K to be ≲10 M⊙ yr‑1. The COS spectra also show a flat rest-frame UV continuum with weak stellar photospheric features, consistent with the presence of recently formed hot stars forming at a rate of ∼10 M⊙ yr‑1, uncorrected for dust extinction. The slope and absorption lines in these UV spectra are similar to those of Lyman Break Galaxies at z≈ 3, albeit those with the highest Lyα equivalent widths and star formation rates. This high-EQW Lyα source is a high-metallicity galaxy rapidly forming stars in structures that look nothing like disks. This mode of star formation could significantly contribute to the spheroidal population of galaxies. The constraint on the luminosity of any O vi line emission is stringent enough to rule out steady and simultaneous gas cooling and star formation, unlike similar systems in the Phoenix Cluster and Abell 1795. The fact that the current star formation rate differs from the local mass cooling rate is consistent with recent simulations of episodic active galactic nucleus feedback and star formation in a cluster atmosphere.

  1. The Velocity Dispersion Function of Very Massive Galaxy Clusters: Abell 2029 and Coma

    NASA Astrophysics Data System (ADS)

    Sohn, Jubee; Geller, Margaret J.; Zahid, H. Jabran; Fabricant, Daniel G.; Diaferio, Antonaldo; Rines, Kenneth J.

    2017-04-01

    Based on an extensive redshift survey for galaxy clusters Abell 2029 and Coma, we measure the luminosity functions (LFs) and stellar mass functions (SMFs) for the entire cluster member galaxies. Most importantly, we measure the velocity dispersion functions (VDFs) for quiescent members. The MMT/Hectospec redshift survey for galaxies in A2029 identifies 982 spectroscopic members; for 838 members, we derive the central velocity dispersion from the spectroscopy. Coma is the only other cluster surveyed as densely. The LFs, SMFs, and VDFs for A2029 and Coma are essentially identical. The SMFs of the clusters are consistent with simulations. The A2029 and Coma VDFs for quiescent galaxies have a significantly steeper slope than those of field galaxies for velocity dispersion ≲ 100 {km} {{{s}}}-1. The cluster VDFs also exceed the field at velocity dispersion ≳ 250 {km} {{{s}}}-1. The differences between cluster and field VDFs are potentially important tests of simulations and of the formation of structure in the universe.

  2. The Sloan Lens ACS Survey. X. Stellar, Dynamical, and Total Mass Correlations of Massive Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Auger, M. W.; Treu, T.; Bolton, A. S.; Gavazzi, R.; Koopmans, L. V. E.; Marshall, P. J.; Moustakas, L. A.; Burles, S.

    2010-11-01

    We use stellar masses, surface photometry, strong-lensing masses, and stellar velocity dispersions (σ e/2) to investigate empirical correlations for the definitive sample of 73 early-type galaxies (ETGs) that are strong gravitational lenses from the SLACS survey. The traditional correlations (fundamental plane (FP) and its projections) are consistent with those found for non-lens galaxies, supporting the thesis that SLACS lens galaxies are representative of massive ETGs (dimensional mass M dim = 1011-1012 M sun). The addition of high-precision strong-lensing estimates of the total mass allows us to gain further insights into their internal structure: (1) the average slope of the total mass-density profile ( ρ_tot∝ r^{-γ'}) is langγ'rang = 2.078 ± 0.027 with an intrinsic scatter of 0.16 ± 0.02; (2) γ' correlates with effective radius (re ) and central mass density, in the sense that denser galaxies have steeper profiles; (3) the dark matter (DM) fraction within re /2 is a monotonically increasing function of galaxy mass and size (due to a mass-dependent central cold DM distribution or due to baryonic DM—stellar remnants or low-mass stars—if the initial mass function is non-universal and its normalization increases with mass); (4) the dimensional mass M dim ≡ 5re σ2 e/2/G is proportional to the total (lensing) mass M _{r_{e}/2}, and both increase more rapidly than stellar mass M * (M _* ∝ {M}_{r_{e}/2}^{0.8}); (5) the mass plane (MP), obtained by replacing surface brightness with surface mass density in the FP, is found to be tighter and closer to the virial relation than the FP and the M*P, indicating that the scatter of those relations is dominated by stellar population effects; (6) we construct the fundamental hyper-plane by adding stellar masses to the MP and find the M * coefficient to be consistent with zero and no residual intrinsic scatter. Our results demonstrate that the dynamical structure of ETGs is not scale invariant and that it is

  3. Possible identification of massive and evolved galaxies at z ≳ 5

    NASA Astrophysics Data System (ADS)

    Mawatari, Ken; Yamada, Toru; Fazio, Giovanni G.; Huang, Jia-Sheng; Ashby, Matthew L. N.

    2016-06-01

    We report on the identification of the old stellar population galaxy candidates at z ≳ 5. We developed a new infrared color selection scheme to isolate galaxies with the strong Balmer breaks at z ≳ 5, and applied it to the ultra-deep and wide infrared survey data from the Spitzer Extended Deep Survey (SEDS) and the UKIRT Infrared Deep Sky Survey. The eight objects satisfying K - [3.6] > 1.3 and K - [3.6] > 2.4([3.6] - [4.5]) + 0.6 are selected in the 0.34 deg2 SEDS Ultra Deep Survey field. Rich multi-wavelength imaging data from optical to far-infrared are also used to reject blending sources and strong nebular line emitters, and we finally obtained the three most likely evolved galaxies at z ≳ 5. Their stacked spectral energy distribution is fitted well with the old stellar population template with M* = (7.5 ± 1.5) × 1010 M⊙, star formation rate = 0.9 ± 0.2 M⊙ yr-1, dust AV < 1, and age =0.7 ± 0.4 Gyr at z = 5.7 ± 0.6, where the dusty star-forming galaxies at z ˜ 2.8 are disfavored because of the faintness in the 24 μm. The stellar mass density of these evolved galaxy candidates, (6 ± 4) × 104 M⊙ Mpc-3, is much lower than that of star-forming galaxies, but the non-zero fraction suggests that initial star-formation and quenching have been completed by z ˜ 6.

  4. MASSIVE BLACK HOLES IN GALAXIES NGC 3377, NGC 3379 AND NGC 4486B

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The three galaxies above are believed to contain central, supermassive black holes. The galaxy NGC 4486B (lower-left) shows a double nucleus (lower-right). The images of NGC 3377 and NGC 4486B are 2.7 arcseconds on a side, and for NGC 3379 the size is 5.4 arcseconds; the lower-right is a blow-up of the central 0.5 arcseconds of NGC 4486B. Credit: Karl Gebhardt (University of Michigan) and Tod Lauer (NOAO)

  5. Galaxy halo formation in the absence of violent relaxation and a universal density profile of the halo center

    SciTech Connect

    Baushev, A. N.

    2014-05-01

    While N-body simulations testify to a cuspy profile of the central region of dark matter halos, observations favor a shallow, cored density profile of the central region of at least some spiral galaxies and dwarf spheroidals. We show that a central profile, very close to the observed one, inevitably forms in the center of dark matter halos if we make a supposition about a moderate energy relaxation of the system during the halo formation. If we assume the energy exchange between dark matter particles during the halo collapse is not too intensive, the profile is universal: it depends almost not at all on the properties of the initial perturbation and is very akin, but not identical, to the Einasto profile with a small Einasto index n ∼ 0.5. We estimate the size of the 'central core' of the distribution, i.e., the extent of the very central region with a respectively gentle profile, and show that the cusp formation is unlikely, even if the dark matter is cold. The obtained profile is in good agreement with observational data for at least some types of galaxies but clearly disagrees with N-body simulations.

  6. Quasars probing quasars. VII. The pinnacle of the cool circumgalactic medium surrounds massive z ∼ 2 galaxies

    SciTech Connect

    Prochaska, J. Xavier; Lau, Marie Wingyee

    2014-12-01

    We survey the incidence and absorption strength of the metal-line transitions C II 1334 and C IV 1548 from the circumgalactic medium (CGM) surrounding z ∼ 2 quasars, which act as signposts for massive dark matter halos M {sub halo} ≈ 10{sup 12.5} M {sub ☉}. On scales of the virial radius (r {sub vir} ≈ 160 kpc), we measure a high covering fraction f{sub C} = 0.73 ± 0.10 to strong C II 1334 absorption (rest equivalent width W {sub 1334} ≥ 0.2 Å), implying a massive reservoir of cool (T ∼ 10{sup 4} K) metal enriched gas. We conservatively estimate a metal mass exceeding 10{sup 8} M {sub ☉}. We propose that these metals trace enrichment of the incipient intragroup/intracluster medium that these halos eventually inhabit. This cool CGM around quasars is the pinnacle among galaxies observed at all epochs, as regards covering the fraction and average equivalent width of H I Lyα and low-ion metal absorption. We argue that the properties of this cool CGM primarily reflect the halo mass, and that other factors such as feedback, star-formation rate, and accretion from the intergalactic medium are secondary. We further estimate that the CGM of massive, z ∼ 2 galaxies accounts for the majority of strong Mg II absorption along random quasar sightlines. Last, we detect an excess of strong C IV 1548 absorption (W {sub 1548} ≥ 0.3 Å) over random incidence to the 1 Mpc physical impact parameter and measure the quasar-C IV cross-correlation function: ξ{sub C} {sub IV-Q}(r)=(r/r{sub 0}){sup −γ} with r{sub 0}=7.5{sub −1.4}{sup +2.8} h{sup −1} Mpc and γ=1.7{sub −0.2}{sup +0.1}. Consistent with previous work on larger scales, we infer that this highly ionized C IV gas traces massive (10{sup 12} M {sub ☉}) halos.

  7. Massive black hole binaries in gas-rich galaxy mergers; multiple regimes of orbital decay and interplay with gas inflows

    NASA Astrophysics Data System (ADS)

    Mayer, Lucio

    2013-12-01

    We revisit the phases of the pairing and sinking of black holes (BHs) in galaxy mergers and circumnuclear discs in light of the results of recent simulations with massive BHs embedded in predominantly gaseous backgrounds. After a general overview we highlight for the first time the existence of a clear transition, for unequal mass BHs, between the regime in which the orbital decay is dominated by the conventional dynamical friction wake and one in which global disc torques associated with density waves launched by the secondary BH as well as co-orbital torques arising from gas gravitationally captured by the BH dominate and lead to faster decay. The new regime intervenes at BH binary separations of a few tens of parsecs and below, following a phase of orbital circularization driven dynamical friction. It bears some resemblance with planet migration in protoplanetary discs. While the orbital timescale is reasonably matched by the migration rate for the Type-I regime, the dominant negative torque arises near the co-rotation resonance, which is qualitatively similar to what is found in the so-called Type-III migration, the fastest migration regime identified so far for planets. This fast decay rate brings the BHs to separations of order 10-1 pc, the resolution limit of our simulations, in less than ˜107 yr in a smooth disc, while the decay timescale can increase to >108 yr in clumpy discs due to gravitational scattering with molecular clouds. Eventual gap opening at sub-pc scale separations will slow down the orbital decay subsequently. How fast the binary BH can reach the separation at which gravitational waves take over will be determined by the nature of the interaction with the circumbinary disc and the complex torques exerted the gas flowing through the edge of such disc, the subject of many recent studies. We also present a new intriguing connection between the conditions required for rapid orbital decay of massive BH binaries and those required for prominent

  8. Discovery of Massive, Mostly Star Formation Quenched Galaxies with Extremely Large Lyα Equivalent Widths at z ˜ 3

    NASA Astrophysics Data System (ADS)

    Taniguchi, Yoshiaki; Kajisawa, Masaru; Kobayashi, Masakazu A. R.; Nagao, Tohru; Shioya, Yasuhiro; Scoville, Nick Z.; Sanders, David B.; Capak, Peter L.; Koekemoer, Anton M.; Toft, Sune; McCracken, Henry J.; Le Fèvre, Olivier; Tasca, Lidia; Sheth, Kartik; Renzini, Alvio; Lilly, Simon; Carollo, Marcella; Kovač, Katarina; Ilbert, Olivier; Schinnerer, Eva; Fu, Hai; Tresse, Laurence; Griffiths, Richard E.; Civano, Francesca

    2015-08-01

    We report a discovery of six massive galaxies with both extremely large Lyα equivalent widths (EWs) and evolved stellar populations at z ˜ 3. These MAssive Extremely STrong Lyα emitting Objects (MAESTLOs) have been discovered in our large-volume systematic survey for strong Lyα emitters (LAEs) with 12 optical intermediate-band data taken with Subaru/Suprime-Cam in the COSMOS field. Based on the spectral energy distribution fitting analysis for these LAEs, it is found that these MAESTLOs have (1) large rest-frame EWs of EW0 (Lyα) ˜ 100-300 Å, (2) M⋆ ˜ 1010.5-1011.1 M⊙, and (3) relatively low specific star formation rates of SFR/M⋆ ˜ 0.03-1 Gyr-1. Three of the six MAESTLOs have extended Lyα emission with a radius of several kiloparsecs, although they show very compact morphology in the HST/ACS images, which correspond to the rest-frame UV continuum. Since the MAESTLOs do not show any evidence for active galactic nuclei, the observed extended Lyα emission is likely to be caused by a star formation process including the superwind activity. We suggest that this new class of LAEs, MAESTLOs, provides a missing link from star-forming to passively evolving galaxies at the peak era of the cosmic star formation history. Based on observations with NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555; also based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; and also based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme ID 179.A-2005 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium.

  9. THE MASSIVE AND DISTANT CLUSTERS OF WISE SURVEY: MOO J1142+1527, A 10{sup 15}M{sub ⊙} GALAXY CLUSTER AT z = 1.19

    SciTech Connect

    Gonzalez, Anthony H.; Gettings, Daniel P.; Decker, Bandon; Brodwin, Mark; Eisenhardt, Peter R. M.; Stern, Daniel; Marrone, Daniel P.; Greer, Christopher H.; Stanford, S. A.; Wylezalek, Dominika; Aldering, Greg; Boone, Kyle; Fagrelius, Parker; Hayden, Brian; Abdulla, Zubair; Carlstrom, John; Leitch, Erik M.; Lin, Yen-Ting; Mantz, Adam B.; Muchovej, Stephen; and others

    2015-10-20

    We present confirmation of the cluster MOO J1142+1527, a massive galaxy cluster discovered as part of the Massive and Distant Clusters of WISE Survey. The cluster is confirmed to lie at z = 1.19, and using the Combined Array for Research in Millimeter-wave Astronomy we robustly detect the Sunyaev–Zel’dovich (SZ) decrement at 13.2σ. The SZ data imply a mass of M{sub 200m} = (1.1 ± 0.2) × 10{sup 15}M{sub ⊙}, making MOO J1142+1527 the most massive galaxy cluster known at z > 1.15 and the second most massive cluster known at z > 1. For a standard ΛCDM cosmology it is further expected to be one of the ∼5 most massive clusters expected to exist at z ≥ 1.19 over the entire sky. Our ongoing Spitzer program targeting ∼1750 additional candidate clusters will identify comparably rich galaxy clusters over the full extragalactic sky.

  10. Probing the cool interstellar and circumgalactic gas of three massive lensing galaxies at z = 0.4-0.7

    NASA Astrophysics Data System (ADS)

    Zahedy, Fakhri S.; Chen, Hsiao-Wen; Rauch, Michael; Wilson, Michelle L.; Zabludoff, Ann

    2016-05-01

    We present multisightline absorption spectroscopy of cool gas around three lensing galaxies at z = 0.4-0.7. These lenses have half-light radii re = 2.6-8 kpc and stellar masses of log M*/M⊙ = 10.9-11.4, and therefore resemble nearby passive elliptical galaxies. The lensed QSO sightlines presented here occur at projected distances of d = 3-15 kpc (or d ≈ 1-2 re) from the lensing galaxies, providing for the first time an opportunity to probe both interstellar gas at r ˜ re and circumgalactic gas at larger radii r ≫ re of these distant quiescent galaxies. We observe distinct gas absorption properties among different lenses and among sightlines of individual lenses. Specifically, while the quadruple lens for HE 0435-1223 shows no absorption features to very sensitive limits along all four sightlines, strong Mg II, Fe II, Mg I, and Ca II absorption transitions are detected along both sightlines near the double lens for HE 0047-1756, and in one of the two sightlines near the double lens for HE 1104-1805. The absorbers are resolved into 8-15 individual components with a line-of-sight velocity spread of Δ v ≈ 300-600 km s-1. The large ionic column densities, log N ≳ 14, observed in two components suggest that these may be Lyman limit or damped Ly α absorbers with a significant neutral hydrogen fraction. The majority of the absorbing components exhibit a uniform supersolar Fe/Mg ratio with a scatter of <0.1 dex across the full Δ v range. Given a predominantly old stellar population in these lensing galaxies, we argue that the observed large velocity width and Fe-rich abundance pattern can be explained by SNe Ia enriched gas at radius r ˜ re. We show that additional spatial constraints in line-of-sight velocity and relative abundance ratios afforded by a multisightline approach provide a powerful tool to resolve the origin of chemically enriched cool gas in massive haloes.

  11. Spitzer 24 Micron Observations of Optical/Near-Infrared-Selected Extremely Red Galaxies: Evidence for Assembly of Massive Galaxies at Z approximately equal to 1-2?

    NASA Technical Reports Server (NTRS)

    Yan, Lin; Choi, Philip I.; Fadda, D.; Marleau, F. R.; Soifer, B. T.; Im, M.; Armus, L.; Frayer, D. T.; Storrie-Lombardi, L. J.; Thompson, D. J.; Teplitz, H. I.; Helou, G.; Appleton, P. N.; Chapman, S.; Fan, F.; Heinrichsen, I.; Lacy, M.; Shupe, D. L.; Squires, G. K.; Surace, J.; Wilson, G.

    2004-01-01

    lower limit on the masses of these 24 micron-detected EROs is 5 x 10(exp 9) to 2 x 10(exp 10) solar masses. It is plausible that some of the starburst EROs are in the midst of a violent transformation to become massive early type galaxies at the epoch of z 1-2.

  12. Rhapsody-G simulations I: the cool cores, hot gas and stellar content of massive galaxy clusters

    NASA Astrophysics Data System (ADS)

    Hahn, Oliver; Martizzi, Davide; Wu, Hao-Yi; Evrard, August E.; Teyssier, Romain; Wechsler, Risa H.

    2017-01-01

    We present the RHAPSODY-G suite of cosmological hydrodynamic AMR zoom simulations of ten massive galaxy clusters at the Mvir ˜ 1015 M⊙ scale. These simulations include cooling and sub-resolution models for star formation and stellar and supermassive black hole feedback. The sample is selected to capture the whole gamut of assembly histories that produce clusters of similar final mass. We present an overview of the successes and shortcomings of such simulations in reproducing both the stellar properties of galaxies as well as properties of the hot plasma in clusters. In our simulations, a long-lived cool-core/non-cool core dichotomy arises naturally, and the emergence of non-cool cores is related to low angular momentum major mergers. Nevertheless, the cool-core clusters exhibit a low central entropy compared to observations, which cannot be alleviated by thermal AGN feedback. For cluster scaling relations we find that the simulations match well the M500 - Y500 scaling of Planck SZ clusters but deviate somewhat from the observed X-ray luminosity and temperature scaling relations in the sense of being slightly too bright and too cool at fixed mass, respectively. Stars are produced at an efficiency consistent with abundance matching constraints and central galaxies have star formation rates consistent with recent observations. While our simulations thus match various key properties remarkably well, we conclude that the shortcomings strongly suggest an important role for non-thermal processes (through feedback or otherwise) or thermal conduction in shaping the intra-cluster medium.

  13. Evidence for Dark Matter Contraction and a Salpeter Initial Mass Function in a Massive Early-type Galaxy

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, A.; Treu, T.; Gavazzi, R.; Marshall, P. J.; Auger, M. W.; Suyu, S. H.; Koopmans, L. V. E.; Bolton, A. S.

    2012-06-01

    Stars and dark matter account for most of the mass of early-type galaxies, but uncertainties in the stellar population and the dark matter profile make it challenging to distinguish between the two components. Nevertheless, precise observations of stellar and dark matter are extremely valuable for testing the many models of structure formation and evolution. We present a measurement of the stellar mass and inner slope of the dark matter halo of a massive early-type galaxy at z = 0.222. The galaxy is the foreground deflector of the double Einstein ring gravitational lens system SDSSJ0946+1006, also known as the "Jackpot." By combining the tools of lensing and dynamics we first constrain the mean slope of the total mass density profile (\\rho _{tot}\\propto r^{-\\gamma ^{\\prime }}) within the radius of the outer ring to be γ' = 1.98 ± 0.02 ± 0.01. Then we obtain a bulge-halo decomposition, assuming a power-law form for the dark matter halo. Our analysis yields γDM = 1.7 ± 0.2 for the inner slope of the dark matter profile, in agreement with theoretical findings on the distribution of dark matter in ellipticals, and a stellar mass from lensing and dynamics M LD * = 5.5-1.3 +0.4 × 1011 M ⊙. By comparing this measurement with stellar masses inferred from stellar population synthesis fitting we find that a Salpeter initial mass function (IMF) provides a good description of the stellar population of the lens while the probability of the IMF being heavier than Chabrier is 95%. Our data suggest that growth by accretion of small systems from a compact red nugget is a plausible formation scenario for this object.

  14. Discovery of an Enormous Lyα Nebula in a Massive Galaxy Overdensity at z = 2.3

    NASA Astrophysics Data System (ADS)

    Cai, Zheng; Fan, Xiaohui; Yang, Yujin; Bian, Fuyan; Prochaska, J. Xavier; Zabludoff, Ann; McGreer, Ian; Zheng, Zhen-Ya; Green, Richard; Cantalupo, Sebastiano; Frye, Brenda; Hamden, Erika; Jiang, Linhua; Kashikawa, Nobunari; Wang, Ran

    2017-03-01

    Enormous Lyα nebulae (ELANe), unique tracers of galaxy density peaks, are predicted to lie at the nodes and intersections of cosmic filamentary structures. Previous successful searches for ELANe have focused on wide-field narrowband surveys or have targeted known sources such as ultraluminous quasi-stellar objects (QSOs) or radio galaxies. Utilizing groups of coherently strong Lyα absorptions, we have developed a new method to identify high-redshift galaxy overdensities and have identified an extremely massive overdensity, BOSS1441, at z=2{--}3. In its density peak, we discover an ELAN that is associated with a relatively faint continuum. To date, this object has the highest diffuse Lyα nebular luminosity of {L}{nebula}=5.1+/- 0.1× {10}44 erg s‑1. Above the 2σ surface brightness limit of SB{}{Lyα }=4.8× {10}-18 erg s‑1 cm‑2 arcsec‑2, this nebula has an end-to-end spatial extent of 442 kpc. This radio-quiet source also has extended C iv λ 1549 and He ii λ 1640 emission on ≳ 30 {kpc} scales. Note that the Lyα, He ii, and C iv emissions all have double-peaked line profiles. Each velocity component has an FWHM of ≈700–1000 km s‑1. We argue that this Lyα nebula could be powered by shocks due to an active galactic nucleus–driven outflow or photoionization by a strongly obscured source.

  15. Transition between order and chaos in a composite disk galaxy model with a massive nucleus and a dark matter halo

    NASA Astrophysics Data System (ADS)

    Caranicolas, Nicolaos D.; Zotos, Euaggelos E.

    2013-02-01

    We investigate the transition from regular to chaotic motion in a composite galaxy model with a disk-halo, a massive dense nucleus and a dark halo component. We obtain relationships connecting the critical value of the mass of the nucleus or the critical value of the angular momentum Lzc, with the mass Mh of the dark halo, where the transition from regular motion to chaos occurs. We also present 3D diagrams connecting the mass of nucleus the energy and the percentage of stars that can show chaotic motion. The fraction of the chaotic orbits observed in the (r,pr) phase plane, as a function of the mass of the dark halo is also computed. We use a semi-numerical method, that is a combination of theoretical and numerical procedure. The theoretical results obtained using the version 8.0 of the Mathematica package, while all the numerical calculations were made using a Bulirsch-Stöer FORTRAN routine in double precision. The results can be obtained in semi-numerical or numerical form and give good description for the connection of the physical quantities entering the model and the transition between regular and chaotic motion. We observe that the mass of the dark halo, the mass of the dense nucleus and the Lz component of the angular momentum, are important physical quantities, as they are linked to the regular or chaotic character of orbits in disk galaxies described by the model. Our numerical experiments suggest, that the amount of the dark matter plays an important role in disk galaxies represented by the model, as the mass of the halo affects, not only the regular or chaotic nature of motion but it is also connected with the existence of the different families of regular orbits. Comparison of the present results with earlier work is also presented.

  16. SMM J04135+10277: A CANDIDATE EARLY-STAGE ''WET-DRY'' MERGER OF TWO MASSIVE GALAXIES AT z = 2.8

    SciTech Connect

    Riechers, Dominik A.

    2013-03-10

    We report interferometric imaging of CO(J = 3{yields}2) emission toward the z = 2.846 submillimeter-selected galaxy SMM J04135+10277, using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). SMM J04135+10277 was previously thought to be a gas-rich, submillimeter-selected quasar, with the highest molecular gas mass among high-z quasars reported in the literature. Our maps at {approx}6 Multiplication-Sign improved linear resolution relative to earlier observations spatially resolve the emission on {approx}1.''7 scales, corresponding to a (lensing-corrected) source radius of {approx}5.2 kpc. They also reveal that the molecular gas reservoir, and thus, likely the submillimeter emission, is not associated with the host galaxy of the quasar, but with an optically faint gas-rich galaxy at 5.''2, or 41.5 kpc projected distance from the active galactic nucleus (AGN). The obscured gas-rich galaxy has a dynamical mass of M{sub dyn} sin{sup 2} i = 5.6 Multiplication-Sign 10{sup 11} M{sub Sun }, corresponding to a gas mass fraction of {approx_equal}21%. Assuming a typical M{sub BH}/M{sub *} ratio for z {approx}> 2 quasars, the two galaxies in this system have an approximate mass ratio of {approx}1.9. Our findings suggest that this quasar-starburst galaxy pair could represent an early stage of a rare major, gas-rich/gas-poor ({sup w}et-dry{sup )} merger of two massive galaxies at z = 2.8, rather than a single, gas-rich AGN host galaxy. Such systems could play an important role in the early buildup of present-day massive galaxies through a submillimeter-luminous starburst phase, and may remain hidden in larger numbers among rest-frame far-infrared-selected quasar samples at low and high redshift.

  17. Life in the fast lane: The dark-matter distribution in the most massive galaxy clusters in the Universe at z>0.5

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald

    2003-07-01

    We propose two-filter ACS observations of a complete sample of 12 very X-ray luminous galaxy clusters at 0.5massive clusters in the universe. Our sample includes the famous systems Cl0016+16 and MS0451-03; all other clusters are new discoveries from the MACS survey. Being the counterparts of the best-studied systems at lower and higher redshift and comprising ALL massive clusters at 0.50.5. HST's unique capabilities will allow us to: 1} measure accurately the clusters' dark matter distribution on scales from tens to more than 500/h_50 kpc from observations of strong and weak gravitational lensing, 2} use galaxy-galaxy lensing to measure the shape, extent, and mass content of the dark-matter halos of both cluster and field galaxies, and 3} study the color morphology of mergers and the star formation history of galaxies in a high-density environment. The proposed observations are complemented by Chandra observations of all our targets {all 12 awarded, 11 executed to date} which provide independent constraints on the dark matter and gas distribution in the cluster cores, as well a by extensive groundbased observations of weak lensing on yet larger scales, galaxy dynamics, and the SZ effect.

  18. Life in the fast lane: The dark-matter distribution in the most massive galaxy clusters in the Universe at z>0.5

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald

    2004-07-01

    We propose two-filter ACS observations of a complete sample of 12 very X-ray luminous galaxy clusters at 0.5massive clusters in the universe. Our sample includes the famous systems Cl0016+16 and MS0451-03; all other clusters are new discoveries from the MACS survey. Being the counterparts of the best-studied systems at lower and higher redshift and comprising ALL massive clusters at 0.50.5. HST's unique capabilities will allow us to: 1} measure accurately the clusters' dark matter distribution on scales from tens to more than 500/h_50 kpc from observations of strong and weak gravitational lensing, 2} use galaxy-galaxy lensing to measure the shape, extent, and mass content of the dark-matter halos of both cluster and field galaxies, and 3} study the color morphology of mergers and the star formation history of galaxies in a high-density environment. The proposed observations are complemented by Chandra observations of all our targets {all 12 awarded, 11 executed to date} which provide independent constraints on the dark matter and gas distribution in the cluster cores, as well a by extensive groundbased observations of weak lensing on yet larger scales, galaxy dynamics, and the SZ effect.

  19. Cosmology with massive neutrinos III: the halo mass function and an application to galaxy clusters

    SciTech Connect

    Costanzi, Matteo; Borgani, Stefano; Villaescusa-Navarro, Francisco; Viel, Matteo; Xia, Jun-Qing; Castorina, Emanuele; Sefusatti, Emiliano E-mail: villaescusa@oats.inaf.it E-mail: xiajq@ihep.ac.cn E-mail: castori@sissa.it

    2013-12-01

    We use a suite of N-body simulations that incorporate massive neutrinos as an extra-set of particles to investigate their effect on the halo mass function. We show that for cosmologies with massive neutrinos the mass function of dark matter haloes selected using the spherical overdensity (SO) criterion is well reproduced by the fitting formula of Tinker et al. (2008) once the cold dark matter power spectrum is considered instead of the total matter power, as it is usually done. The differences between the two implementations, i.e. using P{sub cdm}(k) instead of P{sub m}(k), are more pronounced for large values of the neutrino masses and in the high end of the halo mass function: in particular, the number of massive haloes is higher when P{sub cdm}(k) is considered rather than P{sub m}(k). As a quantitative application of our findings we consider a Planck-like SZ-clusters survey and show that the differences in predicted number counts can be as large as 30% for ∑m{sub ν} = 0.4 eV. Finally, we use the Planck-SZ clusters sample, with an approximate likelihood calculation, to derive Planck-like constraints on cosmological parameters. We find that, in a massive neutrino cosmology, our correction to the halo mass function produces a shift in the σ{sub 8}(Ω{sub m}/0.27){sup γ} relation which can be quantified as Δγ ∼ 0.05 and Δγ ∼ 0.14 assuming one (N{sub ν} = 1) or three (N{sub ν} = 3) degenerate massive neutrino, respectively. The shift results in a lower mean value of σ{sub 8} with Δσ{sub 8} = 0.01 for N{sub ν} = 1 and Δσ{sub 8} = 0.02 for N{sub ν} = 3, respectively. Such difference, in a cosmology with massive neutrinos, would increase the tension between cluster abundance and Planck CMB measurements.

  20. Massive Neutrino Decay Driven Radiative Instabilities, Sub-Structure Survival in Galaxy Clusters and a Nested - Particle-Mesh Code

    NASA Astrophysics Data System (ADS)

    Splinter, Randall John

    1995-01-01

    I have performed a series of studies concerning the clustering of mass on large scales in the universe, with the goal being an increased understanding of the role of various processes in the formation of structure in the universe. One of the first dark matter candidates was the massive neutrino. In this section I investigate the role of a radiative decay mode for a massive neutrino species, and its impact on structure formation. By reviving a concept known as "mock gravity" I attempt to provide seed masses for eventual galaxy formation in a Hot Dark Matter universe. I show that mock gravity is ineffective at generating seed masses for galaxy formation; the ionization rate is too large and the universe becomes fully ionized well before the radiation pressure can have any effect on the clumping of matter. The final section of this thesis presents a series of N-body experiments which are aimed at understanding the theoretical sources of substructure in galaxy clusters. I perform a series of simulations using a variety of power law initial conditions to generate our cluster data sets. From there I use the statistical methods developed by Bird to analyze the subsequent survival of the sub-structures. I find that for a high omega universe that a significant number of clusters should exhibit sub-structure for very long periods of time after their formation. To test whether the sub-structure results are dependent upon the resolution of the N-body code I develop a nested-grid code for use in performing high resolution studies of gravitational instability. In the next section I present an N-body code which features a nested-grid technology. This nested-grid method allows me to extend both the force and mass resolution of a traditional particle-mesh type code. This code will prove extremely useful for studying problems in large-scale structure formation where one is focusing on highly non -linear objects, and hence force and mass resolution are at a premium. In this chapter I

  1. THE ATACAMA COSMOLOGY TELESCOPE: DYNAMICAL MASSES AND SCALING RELATIONS FOR A SAMPLE OF MASSIVE SUNYAEV-ZEL'DOVICH EFFECT SELECTED GALAXY CLUSTERS {sup ,}

    SciTech Connect

    Sifon, Cristobal; Barrientos, L. Felipe; Gonzalez, Jorge; Infante, Leopoldo; Duenner, Rolando; Menanteau, Felipe; Hughes, John P.; Baker, Andrew J.; Hasselfield, Matthew; Marriage, Tobias A.; Crichton, Devin; Gralla, Megan B.; Addison, Graeme E.; Dunkley, Joanna; Battaglia, Nick; Bond, J. Richard; Hajian, Amir; Das, Sudeep; Devlin, Mark J.; Hilton, Matt; and others

    2013-07-20

    We present the first dynamical mass estimates and scaling relations for a sample of Sunyaev-Zel'dovich effect (SZE) selected galaxy clusters. The sample consists of 16 massive clusters detected with the Atacama Cosmology Telescope (ACT) over a 455 deg{sup 2} area of the southern sky. Deep multi-object spectroscopic observations were taken to secure intermediate-resolution (R {approx} 700-800) spectra and redshifts for Almost-Equal-To 60 member galaxies on average per cluster. The dynamical masses M{sub 200c} of the clusters have been calculated using simulation-based scaling relations between velocity dispersion and mass. The sample has a median redshift z = 0.50 and a median mass M{sub 200c}{approx_equal}12 Multiplication-Sign 10{sup 14} h{sub 70}{sup -1} M{sub sun} with a lower limit M{sub 200c}{approx_equal}6 Multiplication-Sign 10{sup 14} h{sub 70}{sup -1} M{sub sun}, consistent with the expectations for the ACT southern sky survey. These masses are compared to the ACT SZE properties of the sample, specifically, the match-filtered central SZE amplitude y{sub 0}-tilde, the central Compton parameter y{sub 0}, and the integrated Compton signal Y{sub 200c}, which we use to derive SZE-mass scaling relations. All SZE estimators correlate with dynamical mass with low intrinsic scatter ({approx}< 20%), in agreement with numerical simulations. We explore the effects of various systematic effects on these scaling relations, including the correlation between observables and the influence of dynamically disturbed clusters. Using the three-dimensional information available, we divide the sample into relaxed and disturbed clusters and find that {approx}50% of the clusters are disturbed. There are hints that disturbed systems might bias the scaling relations, but given the current sample sizes, these differences are not significant; further studies including more clusters are required to assess the impact of these clusters on the scaling relations.

  2. Galaxies

    SciTech Connect

    Not Available

    1981-01-01

    Normal galaxies, radio galaxies, and Seyfert galaxies are considered. The large magellanic cloud and the great galaxy in Andromedia are highlighted. Quasars and BL lacertae objects are also discussed and a review of the spectral observations of all of these galaxies and celestial objects is presented.

  3. THE MASSIVE AND DISTANT CLUSTERS OF WISE SURVEY. II. INITIAL SPECTROSCOPIC CONFIRMATION OF z ∼ 1 GALAXY CLUSTERS SELECTED FROM 10,000 deg{sup 2}

    SciTech Connect

    Stanford, S. A.; Gonzalez, Anthony H.; Gettings, Daniel P.; Brodwin, Mark; Eisenhardt, Peter R. M.; Stern, Daniel; Wylezalek, Dominika

    2014-08-01

    We present optical and infrared imaging and optical spectroscopy of galaxy clusters which were identified as part of an all-sky search for high-redshift galaxy clusters, the Massive and Distant Clusters of WISE Survey (MaDCoWS). The initial phase of MaDCoWS combined infrared data from the all-sky data release of the Wide-field Infrared Survey Explorer (WISE) with optical data from the Sloan Digital Sky Survey to select probable z ∼ 1 clusters of galaxies over an area of 10,000 deg{sup 2}. Our spectroscopy confirms 19 new clusters at 0.7 < z < 1.3, half of which are at z > 1, demonstrating the viability of using WISE to identify high-redshift galaxy clusters. The next phase of MaDCoWS will use the greater depth of the AllWISE data release to identify even higher redshift cluster candidates.

  4. A Mechanism for Stimulating AGN Feedback by Lifting Gas in Massive Galaxies

    NASA Astrophysics Data System (ADS)

    McNamara, B. R.; Russell, H. R.; Nulsen, P. E. J.; Hogan, M. T.; Fabian, A. C.; Pulido, F.; Edge, A. C.

    2016-10-01

    Observation shows that nebular emission, molecular gas, and young stars in giant galaxies are associated with rising X-ray bubbles inflated by radio jets launched from nuclear black holes. We propose a model where molecular clouds condense from low-entropy gas caught in the updraft of rising X-ray bubbles. The low-entropy gas becomes thermally unstable when it is lifted to an altitude where its cooling time is shorter than the time required to fall to its equilibrium location in the galaxy, i.e., {t}{{c}}/{t}{{I}}≲ 1. The infall speed of a cloud is bounded by the lesser of its free-fall and terminal speeds, so that the infall time here can exceed the free-fall time by a significant factor. This mechanism is motivated by Atacama Large Millimeter Array observations revealing molecular clouds lying in the wakes of rising X-ray bubbles with velocities well below their free-fall speeds. Our mechanism would provide cold gas needed to fuel a feedback loop while stabilizing the atmosphere on larger scales. The observed cooling time threshold of ∼ 5× {10}8 {yr}—the clear-cut signature of thermal instability and the onset of nebular emission and star formation—may result from the limited ability of radio bubbles to lift low-entropy gas to altitudes where thermal instabilities can ensue. Outflowing molecular clouds are unlikely to escape, but instead return to the central galaxy in a circulating flow. We contrast our mechanism to precipitation models where the minimum value of {t}{{c}}/{t}{{ff}}≲ 10 triggers thermal instability, which we find to be inconsistent with observation.

  5. Star formation in grand-design, spiral galaxies. Young, massive clusters in the near-infrared

    NASA Astrophysics Data System (ADS)

    Grosbøl, P.; Dottori, H.

    2012-06-01

    Aims: Spiral structure is a prominent feature in many disk galaxies and is often outlined by bright, young objects. We study the distribution of young stellar clusters in grand-design spiral galaxies and thereby determine whether strong spiral perturbations can influence star formation. Methods: Deep, near-infrared JHK-maps were observed for ten nearby, grand-design, spiral galaxies using HAWK-I at the Very Large Telescope. Complete, magnitude-limited candidate lists of star-forming complexes were obtained by searching within the K-band maps. The properties of the complexes were derived from (H - K) - (J - H) diagrams including the identification of the youngest complexes (i.e. ≲7 Myr) and the estimation of their extinction. Results: Young stellar clusters with ages ≲7 Myr have significant internal extinction in the range of AV = 3-7m, while older ones typically have AV < 1m. The cluster luminosity function (CLF) is well-fitted by a power law with an exponent of around -2 and displays no evidence of a high luminosity cut-off. The brightest cluster complexes in the disk reach luminosities of MK = -15.5m or estimated masses of 106 M⊙. At radii with a strong, two-armed spiral pattern, the star formation rate in the arms is higher by a factor of 2-5 than in the inter-arm regions. The CLF in the arms is also shifted towards brighter MK by at least 0.4m. We also detect clusters with colors compatible with Large Magellanic Cloud intermediate age clusters and Milky Way globular clusters. The (J - K) - MK diagram of several galaxies shows, for the brightest clusters, a clear separation between young clusters that are highly attenuated by dust and older ones with low extinction. Conclusions: The gap in the (J - K) - MK diagrams implies that there has been a rapid expulsion of dust at an age around 7 Myr, possibly triggered by supernovae. Strong spiral perturbations concentrate the formation of clusters in the arm regions and shifts their CLF towards brighter magnitudes

  6. Constraining the Effect of Close-Pairs on the Measurements of the Number Density of the Most Massive Galaxies in the Early Universe

    NASA Astrophysics Data System (ADS)

    Marsan, Zehra Cemile; Marchesini, Danilo; Brammer, Gabriel; Muzzin, Adam

    2017-01-01

    The observed number densities of the most massive galaxies in the early universe drive the ongoing pursuit of understanding the physical processes responsible for galaxy formation and evolution. We present the analysis of close-pairs serendipitously discovered among a sample of very massive (log(Mstar/M⊙) > 11.2) galaxies at 1.5 < z < 3.5 selected for HST/WFC3 F160W band imaging follow-up from the UltraVISTA DR1, NMBS-II and UDS DR8 surveys. The high-resolution rest-frame optical morphologies reveal that ~1/3 of the follow-up sample shows a close companion that is unresolved in the ground-based Ks band imaging. We investigate the effect of the pairs/multiplets on the number density of massive galaxies at 1.5

  7. ON THE INTERMEDIATE-REDSHIFT CENTRAL STELLAR MASS-HALO MASS RELATION, AND IMPLICATIONS FOR THE EVOLUTION OF THE MOST MASSIVE GALAXIES SINCE z ∼ 1

    SciTech Connect

    Shankar, Francesco; Buchan, Stewart; Guo, Hong; Zheng, Zheng; Bouillot, Vincent; Rettura, Alessandro; Meert, Alan; Bernardi, Mariangela; Sheth, Ravi; Vikram, Vinu; Kravtsov, Andrey; Marchesini, Danilo; Behroozi, Peter; Maraston, Claudia; Capozzi, Diego; Ascaso, Begoña; Huertas-Company, Marc; Lemaux, Brian C.; Gal, Roy R.; Lubin, Lori M.; and others

    2014-12-20

    The stellar mass-halo mass relation is a key constraint in all semi-analytic, numerical, and semi-empirical models of galaxy formation and evolution. However, its exact shape and redshift dependence remain under debate. Several recent works support a relation in the local universe steeper than previously thought. Based on comparisons with a variety of data on massive central galaxies, we show that this steepening holds up to z ∼ 1 for stellar masses M {sub star} ≳ 2 × 10{sup 11} M {sub ☉}. Specifically, we find significant evidence for a high-mass end slope of β ≳ 0.35-0.70 instead of the usual β ≲ 0.20-0.30 reported by a number of previous results. When including the independent constraints from the recent Baryon Oscillation Spectroscopic Survey clustering measurements, the data, independent of any systematic errors in stellar masses, tend to favor a model with a very small scatter (≲ 0.15 dex) in stellar mass at fixed halo mass, in the redshift range z < 0.8 and for M {sub star} > 3 × 10{sup 11} M {sub ☉}, suggesting a close connection between massive galaxies and host halos even at relatively recent epochs. We discuss the implications of our results with respect to the evolution of the most massive galaxies since z ∼ 1.

  8. Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the build-up of massive E-S0's

    NASA Astrophysics Data System (ADS)

    Gallego, Jesús; Prieto, Mercedes; Eliche-Moral, M. Carmen; Balcells, Marc; Cristóbal-Hornillos, David; Erwin, Peter; Abreu, David; Domínguez-Palmero, Lilian; Hempel, Angela; López-Sanjuan, Carlos; Guzmán, Rafael; Pérez-González, Pablo G.; Barro, Guillermo; Zamorano, Jaime

    2013-07-01

    Some recent observations seem to disagree with hierarchical theories of galaxy formation on the role of major mergers in a late build-up of massive early-type galaxies. We re-address this question by analysing the morphology, structural distortion level, and star formation enhancement of a sample of massive galaxies (M* > 5 × 1010M⊙) lying on the Red Sequence and its surroundings at 0.3 < z < 1.5. We have used an initial sample of ~1800 sources with Ks < 20.5 mag over an area ~155 arcmin2 on the Groth Strip, combining data from the Rainbow Extragalactic Database and the GOYA Survey. Red galaxy classes that can be directly associated to intermediate stages of major mergers and to their final products have been defined. For the first time we report observationally the existence of a dominant evolutionary path among massive red galaxies at 0.6 < z < 1.5, consisting in the conversion of irregular disks into irregular spheroids, and of these ones into regular spheroids. This result points to: 1) the massive red regular galaxies at low redshifts derive from the irregular ones populating the Red Sequence and its neighbourhood at earlier epochs up to z ~ 1.5; 2) the progenitors of the bulk of present-day massive red regular galaxies have been blue disks that have migrated to the Red Sequence majoritarily through major mergers at 0.6 < z < 1.2 (these mergers thus starting at z ~ 1.5); 3) the formation of E-S0's that end up with M* > 1011M⊙ at z = 0 through gas-rich major mergers has frozen since z ~ 0.6. Our results support that major mergers have played the dominant role in the definitive build-up of present-day E-S0's with M* > 1011M⊙ at 0.6 < z < 1.2, in good agreement with the hierarchical scenario proposed in the Eliche-Moral et al. (2010a) model (see also Eliche-Moral et al. 2010b). This study is published in Prieto et al. (2012). Supported by the Spanish Ministry of Science and Innovation (MICINN) under projects AYA2009-10368, AYA2006-12955, AYA2010-21887-C04

  9. Baryon content of massive galaxy clusters at 0.57 < z < 1.33

    NASA Astrophysics Data System (ADS)

    Chiu, I.; Mohr, J.; McDonald, M.; Bocquet, S.; Ashby, M. L. N.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Brodwin, M.; Desai, S.; Dietrich, J. P.; Forman, W. R.; Gangkofner, C.; Gonzalez, A. H.; Hennig, C.; Liu, J.; Reichardt, C. L.; Saro, A.; Stalder, B.; Stanford, S. A.; Song, J.; Schrabback, T.; Šuhada, R.; Strazzullo, V.; Zenteno, A.

    2016-01-01

    We study the stellar, brightest cluster galaxy (BCG) and intracluster medium (ICM) masses of 14 South Pole Telescope (SPT) selected galaxy clusters with median redshift z = 0.9 and mass M500 = 6 × 1014 M⊙. We estimate stellar masses for each cluster and BCG using six photometric bands, the ICM mass using X-ray observations and the virial masses using the SPT Sunyaev-Zel'dovich effect signature. At z = 0.9, the BCG mass M_{star }^{BCG} constitutes 0.12 ± 0.01 per cent of the halo mass for a 6 × 1014 M⊙ cluster, and this fraction falls as M_{500}^{-0.58± 0.07}. The cluster stellar mass function has a characteristic mass M0 = 1011.0 ± 0.1 M⊙, and the number of galaxies per unit mass in clusters is larger than in the field by a factor of 1.65 ± 0.20. We combine our SPT sample with previously published samples at low redshift and correct to a common initial mass function and for systematic virial mass differences. We then explore mass and redshift trends in the stellar fraction f⋆, the ICM fraction fICM, the collapsed baryon fraction fc and the baryon fraction fb. At a pivot mass of 6 × 1014 M⊙ and redshift z = 0.9, the characteristic values are f⋆ = 1.1 ± 0.1 per cent, fICM = 9.6 ± 0.5 per cent, fc = 10.7 ± 1.1 per cent and fb = 10.7 ± 0.6 per cent. These fractions all vary with cluster mass at high significance, with higher mass clusters having lower f⋆ and fc and higher fICM and fb. When accounting for a 15 per cent systematic virial mass uncertainty, there is no statistically significant redshift trend at fixed mass. Our results support the scenario where clusters grow through accretion from subclusters (higher f⋆, lower fICM) and the field (lower f⋆, higher fICM), balancing to keep f⋆ and fICM approximately constant since z ˜ 0.9.

  10. Massive Stars

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Villaver, Eva

    2009-11-01

    Participants; Preface Mario Livio and Eva Villaver; 1. High-mass star formation by gravitational collapse of massive cores M. R. Krumholz; 2. Observations of massive star formation N. A. Patel; 3. Massive star formation in the Galactic center D. F. Figer; 4. An X-ray tour of massive star-forming regions with Chandra L. K. Townsley; 5. Massive stars: feedback effects in the local universe M. S. Oey and C. J. Clarke; 6. The initial mass function in clusters B. G. Elmegreen; 7. Massive stars and star clusters in the Antennae galaxies B. C. Whitmore; 8. On the binarity of Eta Carinae T. R. Gull; 9. Parameters and winds of hot massive stars R. P. Kudritzki and M. A. Urbaneja; 10. Unraveling the Galaxy to find the first stars J. Tumlinson; 11. Optically observable zero-age main-sequence O stars N. R. Walborn; 12. Metallicity-dependent Wolf-Raynet winds P. A. Crowther; 13. Eruptive mass loss in very massive stars and Population III stars N. Smith; 14. From progenitor to afterlife R. A. Chevalier; 15. Pair-production supernovae: theory and observation E. Scannapieco; 16. Cosmic infrared background and Population III: an overview A. Kashlinsky.

  11. The Massive Black Hole in the Dwarf Galaxy NGC 4486B

    NASA Astrophysics Data System (ADS)

    Bender, A.; Green, R. F.; Gebhardt, K.; Bower, G. A.; Kormendy, J.; Lauer, T.; Richstone, D. O.; STIS IDT Galaxy Nuclei Team; Nuker Team

    2003-12-01

    We report results from the application of a three-integral galactic dynamical model to NGC 4486B. This dwarf E1 companion to M87 has long been known to be an outlier in the Fundamental Plane. Kormendy and Magorrian et al. found a substantial central black hole mass, making it an outlier in the MBH to Lbulge relationship as well. From the modeling we are able to determine the extent to which NGC 4486B follows the MBH - sigma relation more closely than the other bulge galaxy relationships. The other unique feature NGC 4486B exhibits is a double nucleus structure, the second of only two observed. We combine the high resolution of STIS spectra with ground based data to form a more complete description of the line-of-sight velocity distributions (LOSVDs) in the nuclear region of NGC 4486B. Through the increased resolution of the dynamics and the three-integral model, we place an improved constraint on the mass-to-light ratio and black hole mass. Bender's research was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation through Scientific Program Order No. 3 (AST-0243875) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF. RG and GB were supported by NASA for the STIS Instrument Definition Team. This work is a collaboration with the STIS Instrument Definition Team galaxy nuclei group, which also includes John Hutchings, Charles Joseph, Mary Elizabeth Kaiser, Charles Nelson, Donna Weistrop, and Bruce Woodgate. This work is a collaboration with the Nuker Team, which also includes Ralf Bender, Alan Dressler, Sandra Faber, Alex Filippenko, Carl Grillmair, Luis Ho, John Magorrian, Jason Pinkney, Christos Siopis, and Scott Tremaine.

  12. Purely Dry Mergers do not Explain the Observed Evolution of Massive Early-type Galaxies since z ~ 1

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Alessandro; Nipoti, Carlo; Treu, Tommaso

    2014-05-01

    Several studies have suggested that the observed size evolution of massive early-type galaxies (ETGs) can be explained as a combination of dry mergers and progenitor bias, at least since z ~ 1. In this paper we carry out a new test of the dry-merger scenario based on recent lensing measurements of the evolution of the mass density profile of ETGs. We construct a theoretical model for the joint evolution of the size and mass density profile slope γ' driven by dry mergers occurring at rates given by cosmological simulations. Such dry-merger model predicts a strong decrease of γ' with cosmic time, inconsistent with the almost constant γ' inferred from observations in the redshift range 0 < z < 1. We then show with a simple toy model that a modest amount of cold gas in the mergers—consistent with the upper limits on recent star formation in ETGs—is sufficient to reconcile the model with measurements of γ'. By fitting for the amount of gas accreted during mergers, we find that models with dissipation are consistent with observations of the evolution in both size and density slope, if ~4% of the total final stellar mass arises from the gas accreted since z ~ 1. Purely dry merger models are ruled out at >99% CL. We thus suggest a scenario where the outer regions of massive ETGs grow by accretion of stars and dark matter, while small amounts of dissipation and nuclear star formation conspire to keep the mass density profile constant and approximately isothermal.

  13. Purely dry mergers do not explain the observed evolution of massive early-type galaxies since z ∼ 1

    SciTech Connect

    Sonnenfeld, Alessandro; Treu, Tommaso; Nipoti, Carlo

    2014-05-10

    Several studies have suggested that the observed size evolution of massive early-type galaxies (ETGs) can be explained as a combination of dry mergers and progenitor bias, at least since z ∼ 1. In this paper we carry out a new test of the dry-merger scenario based on recent lensing measurements of the evolution of the mass density profile of ETGs. We construct a theoretical model for the joint evolution of the size and mass density profile slope γ' driven by dry mergers occurring at rates given by cosmological simulations. Such dry-merger model predicts a strong decrease of γ' with cosmic time, inconsistent with the almost constant γ' inferred from observations in the redshift range 0 < z < 1. We then show with a simple toy model that a modest amount of cold gas in the mergers—consistent with the upper limits on recent star formation in ETGs—is sufficient to reconcile the model with measurements of γ'. By fitting for the amount of gas accreted during mergers, we find that models with dissipation are consistent with observations of the evolution in both size and density slope, if ∼4% of the total final stellar mass arises from the gas accreted since z ∼ 1. Purely dry merger models are ruled out at >99% CL. We thus suggest a scenario where the outer regions of massive ETGs grow by accretion of stars and dark matter, while small amounts of dissipation and nuclear star formation conspire to keep the mass density profile constant and approximately isothermal.

  14. The SINS/zC-SINF survey of z ∼ 2 galaxy kinematics: Evidence for powerful active galactic nucleus-driven nuclear outflows in massive star-forming galaxies

    SciTech Connect

    Förster Schreiber, N. M.; Genzel, R.; Kurk, J. D.; Lutz, D.; Tacconi, L. J.; Wuyts, S.; Bandara, K.; Buschkamp, P.; Davies, R.; Eisenhauer, F.; Lang, P.; Newman, S. F.; Burkert, A.; Carollo, C. M.; Lilly, S. J.; Cresci, G.; Daddi, E.; Mainieri, V.; Mancini, C.; and others

    2014-05-20

    We report the detection of ubiquitous powerful nuclear outflows in massive (≥10{sup 11} M {sub ☉}) z ∼ 2 star-forming galaxies (SFGs), which are plausibly driven by an active galactic nucleus (AGN). The sample consists of the eight most massive SFGs from our SINS/zC-SINF survey of galaxy kinematics with the imaging spectrometer SINFONI, six of which have sensitive high-resolution adaptive optics-assisted observations. All of the objects are disks hosting a significant stellar bulge. The spectra in their central regions exhibit a broad component in Hα and forbidden [N II] and [S II] line emission, with typical velocity FWHM ∼ 1500 km s{sup –1}, [N II]/Hα ratio ≈ 0.6, and intrinsic extent of 2-3 kpc. These properties are consistent with warm ionized gas outflows associated with Type 2 AGN, the presence of which is confirmed via independent diagnostics in half the galaxies. The data imply a median ionized gas mass outflow rate of ∼60 M {sub ☉} yr{sup –1} and mass loading of ∼3. At larger radii, a weaker broad component is detected but with lower FWHM ∼485 km s{sup –1} and [N II]/Hα ≈ 0.35, characteristic for star formation-driven outflows as found in the lower-mass SINS/zC-SINF galaxies. The high inferred mass outflow rates and frequent occurrence suggest that the nuclear outflows efficiently expel gas out of the centers of the galaxies with high duty cycles and may thus contribute to the process of star formation quenching in massive galaxies. Larger samples at high masses will be crucial in confirming the importance and energetics of the nuclear outflow phenomenon and its connection to AGN activity and bulge growth.

  15. VizieR Online Data Catalog: Massive galaxies in Extended Groth Strip (Trujillo+, 2007)

    NASA Astrophysics Data System (ADS)

    Trujillo, I.; Conselice, C. J.; Bundy, K.; Cooper, M. C.; Eisenhardt, P.; Ellis, R. S.

    2008-03-01

    We use the Palomar Observatory Wide-field Infrared (POWIR)/DEEP-2 survey (Davis et al., 2003, SPIE, Vol. 4834, p. 161; Bundy et al., 2006ApJ...651..120B ; Conselice et al., 2007ApJ...660L..55C, 2007MNRAS.381..962C) to define a sample of 831 galaxies with masses larger than 1011h70-2M{sun} located over ~710arcmin2 in the Extended Groth Strip (EGS). This field (63 Hubble Space Telescope tiles) was imaged with the Advanced Camera for Surveys (ACS) in the V band (F606W, 2660s) and I band (F814W, 2100s). Each tile was observed in four exposures that were combined to produce a pixel scale of 0.03arcsec, with a point spread function (PSF) of 0.12arcsec full width half-maximum (FWHM). In addition to the HST data, optical imaging from the CanadaFranceHawaii Telescope 3.6-m telescope in the B, R and I bands taken with the CFH12K camera was used. Integration times for these observations were 1h in B and R, and 2h in I. Limiting magnitudes reached are B=24.5 (AB, 8{sigma}), R=24.2 (AB, 8{sigma}) and I=23.5 (AB, 8{sigma}). The details of the data reduction for this data are provided in Coil et al. (2004ApJ...617..765C). (1 data file).

  16. Constraints on cold dark matter theories from observations of massive x-ray-luminous clusters of galaxies at high redshift

    NASA Technical Reports Server (NTRS)

    Luppino, G. A.; Gioia, I. M.

    1995-01-01

    During the course of a gravitational lensing survey of distant, X-ray selected Einstein Observatory Extended Medium Sensitivity Survey (EMSS) clusters of galaxies, we have studied six X-ray-luminous (L(sub x) greater than 5 x 10(exp 44)(h(sub 50)(exp -2))ergs/sec) clusters at redshifts exceeding z = 0.5. All of these clusters are apparently massive. In addition to their high X-ray luminosity, two of the clusters at z approximately 0.6 exhibit gravitationally lensed arcs. Furthermore, the highest redshift cluster in our sample, MS 1054-0321 at z = 0.826, is both extremely X-ray luminous (L(sub 0.3-3.5keV)=9.3 x 10(exp 44)(h(sub 50)(exp -2))ergs/sec) and exceedingly rich with an optical richness comparable to an Abell Richness Class 4 cluster. In this Letter, we discuss the cosmological implications of the very existence of these clusters for hierarchical structure formation theories such as standard Omega = 1 CDM (cold dark matter), hybrid Omega = 1 C + HDM (hot dark matter), and flat, low-density Lambda + CDM models.

  17. The physics of massive OB stars in different parent galaxies. 1: Ultraviolet and optical spectral morphology in the Magellanic Clouds

    NASA Technical Reports Server (NTRS)

    Walborn, Nolan R.; Lennon, Daniel J.; Haser, Stephan M.; Kudritzki, Rolf-Peter; Voels, Stephen A.

    1995-01-01

    Hubble Space Telescope/Faint Object Spectrograph (HST/FOS) and European Space Observatory (ESO) 3.6-m/CASPEC observations have been made of 18 stars ranging in spectral type from O3 through B0.5 Ia, half of them in each of the Large and Small Magellanic Clouds, in order to investigate massive stellar winds and evolution as a function of metallicity. The spectroscopic data are initially presented and described here in an atlas format. The relative weakness of the stellar-wind features in the SMC early O V spectra, due to their metal deficiency, is remarkable. Because of their unsaturated profiles, discrete absorption components can be detected in many of them, which is generally not possible in LMC and Galactic counterparts at such early types, or even in SMC giants and supergiants. On the other hand, an O3 III spectrum in the SMC has a weak C IV but strong N V wind profile, possibly indicating the presence of processed material. Wind terminal velocities are also given and intercompared between similar spectral types in the two galaxies. In general, the terminal velocities of the SMC stars are smaller, in qualitative agreement with the predictions of radiation-driven wind theory. Further analyses in progress will provide atmospheric and wind parameters for these stars, which will be relevant to evolutionary models and the interpretation of composite starburst spectra.

  18. Subsonic evolution of the radio bubbles in the nearby massive early-type galaxy NGC 4472: uplift, buoyancy, and heating

    NASA Astrophysics Data System (ADS)

    Kraft, Ralph P.; Gendron Marsolais, Marie-Lou; Bogdan, Akos; Su, Yuanyuan; Forman, William R.; Hlavacek-Larrondo, Julie; Jones, Christine; Nulsen, Paul; Randall, Scott W.; Roediger, Elke

    2017-01-01

    We present results from a deep (380 ks) Chandra observation of the hot gas in the nearby massive early-type galaxy NGC 4472. X-ray cavities were previously reported coincident with the radio lobes (Biller et al. 2004). In our deeper observation, we confirm the presence of the cavities and detect rims of enhanced emission surrounding the bubbles. The temperature of the gas in these rims is less than that of the ambient medium, demonstrating that they cold, low entropy material that has been drawn up from the group center by the buoyant rise of the bubbles and not shocks from supersonic inflation of the lobes. Interestingly, the gravitational energy required to lift these lobes from the group center is a significant fraction of the bubble enthalpy. This suggests that uplift by AGN bubbles may play an important role in some cases in offsetting the radiative cooling at cluster and group centers. This uplift also provides an efficient means of transporting enriched material from the group center to large radii.

  19. Luminous Infrared Galaxies. III. Multiple Merger, Extended Massive Star Formation, Galactic Wind, and Nuclear Inflow in NGC 3256

    NASA Astrophysics Data System (ADS)

    Lípari, S.; Díaz, R.; Taniguchi, Y.; Terlevich, R.; Dottori, H.; Carranza, G.

    2000-08-01

    We report detailed evidence for multiple merger, extended massive star formation, galactic wind, and circular/noncircular motions in the luminous infrared galaxy NGC 3256, based on observations of high-resolution imaging (Hubble Space Telescope, ESO NTT), and extensive spectroscopic data (more than 1000 spectra, collected at Estación Astrofísica de Bosque Alegre, Complejo Astronómico el Leoncito, Cerro Tololo InterAmerican Observatory, and IUE observatories). We find in a detailed morphological study (resolution ~15 pc) that the extended massive star formation process detected previously in NGC 3256 shows extended triple asymmetrical spiral arms (r~5 kpc), emanating from three different nuclei. The main optical nucleus shows a small spiral disk (r~500 pc), which is a continuation of the external one and reaches the very nucleus. The core shows blue elongated structure (50 pc×25 pc) and harbors a blue stellar cluster candidate (r~8 pc). We discuss this complex morphology in the framework of an extended massive star formation driven by a multiple merger process (models of Hernquist et al. and Taniguchi et al.). We study the kinematics of this system and present a detailed Hα velocity field for the central region (40''×40'' rmax~30''~5 kpc), with a spatial resolution of 1" and errors of +/-15 km s-1. The color and isovelocity maps show mainly (1) a kinematic center of circular motion with ``spider'' shape, located between the main optical nucleus and the close (5") mid-IR nucleus and (2) noncircular motions in the external parts. We obtained three ``sinusoidal rotation curves'' (from the Hα velocity field) around position angle (P.A.) ~55°, ~90°, and ~130°. In the main optical nucleus we found a clear ``outflow component'' associated with galactic winds plus an ``inflow radial motion.'' The outflow component was also detected in the central and external regions (r<=5-6 kpc). The main axis of the inflow region (P.A.~80deg) is practically perpendicular to the

  20. Detecting tidal disruption events of massive black holes in normal galaxies with the Einstein Probe

    NASA Astrophysics Data System (ADS)

    Yuan, W.; Komossa, S.; Zhang, C.; Feng, H.; Ling, Z.-X.; Zhao, D. H.; Zhang, S.-N.; Osborne, J. P.; O'Brien, P.; Willingale, R.; Lapington, J.; Lapington

    2016-02-01

    Stars are tidally disrupted and accreted when they approach massive black holes (MBHs) closely, producing a flare of electromagnetic radiation. The majority of the (approximately two dozen) tidal disruption events (TDEs) identified so far have been discovered by their luminous, transient X-ray emission. Once TDEs are detected in much larger numbers, in future dedicated transient surveys, a wealth of new applications will become possible. Here, we present the proposed Einstein Probe mission, which is a dedicated time-domain soft X-ray all-sky monitor aiming at detecting X-ray transients including TDEs in large numbers. The mission consists of a wide-field micro-pore Lobster-eye imager (60° × 60°), and is designed to carry out an all-sky transient survey at energies of 0.5-4 keV. It will also carry a more sensitive telescope for X-ray follow-ups, and will be capable of issuing public transient alerts rapidly. Einstein Probe is expected to revolutionise the field of TDE research by detecting several tens to hundreds of events per year from the early phase of flares, many with long-term, well sampled lightcurves.

  1. Formation and Evolution of Massive Stars, and the Chemical Evolution of Galaxies

    NASA Astrophysics Data System (ADS)

    Rosa, Michael

    1991-07-01

    FOS spectra at R = 560, completely covering thewavelength range 1150 A to 9260 A will be obtained of the cores of 4 giant H IIregions in M 101. Taken through one and the same aperture, the UV, visualand far-red emission line spectra of the ionized gas will allow for the firsttime an accurate determina- tion of the C/O abundance ratio in an extragalacticobject over a wide range of O/H abundances. Furthermore, the S/O abundance ratiowill be obtained with much higher precision than possible from ground using theprominent [S III] 9036 A line, unaffected by strong H2O atmosphericabsorption. Finally, the spatially integrated spectra of the ionizing star clusterswill be analyzed usingwfc evolutionary population synthesis models. Because the whole spectral range is observed through the same aperture, scaling errorsbetween ground based and IUE UV data, which have been so far a major obstaclein such an analysis, will be absent. The nebular continuous emission, which iscontributing typically 50 % of the total flux at 3000 A, can be veryaccurately estimated using the H BETA line flux obtained through the same aperture.The data will be discussed in the context of galactic chemical evolution, forwhich C/O and S/O gradients, which are indicative of contributions from differentstellar mass ranges, are of particular interest. The stellar initial massfunction and the evolutionary scenarios for massive stars will be studied over arange of metallicity from 1/5 to 2 times the solar neighborhood value.

  2. New Constraints on Dark Energy from Chandra X-rayObservations of the Largest Relaxed Galaxy Clusters

    SciTech Connect

    Allen, S.W.; Rapetti, D.A.; Schmidt, R.W.; Ebeling, H.; Morris, G.; Fabian, A.C.; /Cambridge U., Inst. of Astron.

    2007-06-06

    We present constraints on the mean matter density, {Omega}{sub m}, dark energy density, {Omega}{sub DE}, and the dark energy equation of state parameter, w, using Chandra measurements of the X-ray gas mass fraction (fgas) in 42 hot (kT > 5keV), X-ray luminous, dynamically relaxed galaxy clusters spanning the redshift range 0.05 < z < 1.1. Using only the fgas data for the 6 lowest redshift clusters at z < 0.15, for which dark energy has a negligible effect on the measurements, we measure {Omega}{sub m}=0.28{+-}0.06 (68% confidence, using standard priors on the Hubble Constant, H{sub 0}, and mean baryon density, {Omega}{sub b}h{sup 2}). Analyzing the data for all 42 clusters, employing only weak priors on H{sub 0} and {Omega}{sub b}h{sup 2}, we obtain a similar result on {Omega}{sub m} and detect the effects of dark energy on the distances to the clusters at {approx}99.99% confidence, with {Omega}{sub DE}=0.86{+-}0.21 for a non-flat LCDM model. The detection of dark energy is comparable in significance to recent SNIa studies and represents strong, independent evidence for cosmic acceleration. Systematic scatter remains undetected in the f{sub gas} data, despite a weighted mean statistical scatter in the distance measurements of only {approx}5%. For a flat cosmology with constant w, we measure {Omega}{sub m}=0.28{+-}0.06 and w=-1.14{+-}0.31. Combining the fgas data with independent constraints from CMB and SNIa studies removes the need for priors on {Omega}{sub b}h{sup 2} and H{sub 0} and leads to tighter constraints: {Omega}{sub m}=0.253{+-}0.021 and w=-0.98{+-}0.07 for the same constant-w model. More general analyses in which we relax the assumption of flatness and/or allow evolution in w remain consistent with the cosmological constant paradigm. Our analysis includes conservative allowances for systematic uncertainties. The small systematic scatter and tight constraints bode well for future dark energy studies using the f{sub gas} method.

  3. Inferring the star-formation histories of the most massive and passive early-type galaxies at z < 0.3

    NASA Astrophysics Data System (ADS)

    Citro, Annalisa; Pozzetti, Lucia; Moresco, Michele; Cimatti, Andrea

    2016-07-01

    Context. In the Λ cold dark matter (ΛCDM) cosmological framework, massive galaxies are the end-points of the hierarchical evolution and are therefore key probes for understanding how the baryonic matter evolves within the dark matter halos. Aims: The aim of this work is to use the archaeological approach in order to infer the stellar population properties and star formation histories of the most massive (M > 1010.75 M⊙) and passive early-type galaxies (ETGs) at 0 < z < 0.3 (corresponding to a cosmic time interval of ~3.3 Gyr) based on stacked, high signal-to-noise (S/N), spectra extracted from the Sloan Digital Sky Survey (SDSS). Our study is focused on the most passive ETGs in order to avoid the contamination of galaxies with residual star formation activity and extract the evolutionary information on the oldest envelope of the global galaxy population. Methods: Unlike most previous studies in this field, we did not rely on individual absorption features such as the Lick indices, but we used the information present in the full spectrum with the STARLIGHT public code, adopting different stellar population synthesis models. Successful tests have been performed to assess the reliability of STARLIGHT to retrieve the evolutionary properties of the ETG stellar populations such as the age, metallicity and star formation history. The results indicate that these properties can be derived with accuracy better than 10% at S/N ≳ 10-20, and also that the procedure of stacking galaxy spectra does not introduce significant biases into their retrieval. Results: Based on our spectral analysis, we found that the ETGs of our sample are very old systems - the most massive ones are almost as old as the Universe. The stellar metallicities are slightly supersolar, with a mean of Z ~ 0.027 ± 0.002 and Z ~ 0.029 ± 0.0015 (depending on the spectral synthesis models used for the fit) and do not depend on redshift. Dust extinction is very low, with a mean of AV ~ 0.08 ± 0.030 mag

  4. Planck's dusty GEMS. III. A massive lensing galaxy with a bottom-heavy stellar initial mass function at z = 1.5

    NASA Astrophysics Data System (ADS)

    Cañameras, R.; Nesvadba, N. P. H.; Kneissl, R.; Limousin, M.; Gavazzi, R.; Scott, D.; Dole, H.; Frye, B.; Koenig, S.; Le Floc'h, E.; Oteo, I.

    2017-03-01

    We study the properties of the foreground galaxy of the Ruby, the brightest gravitationally lensed high-redshift galaxy on the sub-millimeter sky as probed by the Planck satellite, and part of our sample of Planck's dusty GEMS. The Ruby consists of an Einstein ring of 1.4'' diameter at z = 3.005 observed with ALMA at 0.1'' resolution, centered on a faint, red, massive lensing galaxy seen with HST/WFC3, which itself has an exceptionally high redshift, z = 1.525 ± 0.001, as confirmed with VLT/X-shooter spectroscopy. Here we focus on the properties of the lens and the lensing model obtained with LENSTOOL. The rest-frame optical morphology of this system is strongly dominated by the lens, while the Ruby itself is highly obscured, and contributes less than 10% to the photometry out to the K band. The foreground galaxy has a lensing mass of (3.70 ± 0.35) × 1011M⊙. Magnification factors are between 7 and 38 for individual clumps forming two image families along the Einstein ring. We present a decomposition of the foreground and background sources in the WFC3 images, and stellar population synthesis modeling with a range of star-formation histories for Chabrier and Salpeter initial mass functions (IMFs). Only the stellar mass range obtained with the latter agrees well with the lensing mass. This is consistent with the bottom-heavy IMFs of massive high-redshift galaxies expected from detailed studies of the stellar masses and mass profiles of their low-redshift descendants, and from models of turbulent gas fragmentation. This may be the first direct constraint on the IMF in a lens at z = 1.5, which is not a cluster central galaxy. Based on ALMA data obtained with program 2015.1.01518S and VLT data obtained with programs 291.A-5014 and 295.A-5017.

  5. Evidence for wide-spread active galactic nucleus-driven outflows in the most massive z ∼ 1-2 star-forming galaxies

    SciTech Connect

    Genzel, R.; Förster Schreiber, N. M.; Rosario, D.; Lang, P.; Lutz, D.; Wisnioski, E.; Wuyts, E.; Wuyts, S.; Bandara, K.; Bender, R.; Berta, S.; Kurk, J.; Mendel, J. T.; Tacconi, L. J.; Wilman, D.; Beifiori, A.; Burkert, A.; Buschkamp, P.; Chan, J.; Brammer, G. E-mail: genzel@mpe.mpg.de; and others

    2014-11-20

    In this paper, we follow up on our previous detection of nuclear ionized outflows in the most massive (log(M {sub *}/M {sub ☉}) ≥ 10.9) z ∼ 1-3 star-forming galaxies by increasing the sample size by a factor of six (to 44 galaxies above log(M {sub *}/M {sub ☉}) ≥ 10.9) from a combination of the SINS/zC-SINF, LUCI, GNIRS, and KMOS{sup 3D}spectroscopic surveys. We find a fairly sharp onset of the incidence of broad nuclear emission (FWHM in the Hα, [N II], and [S II] lines ∼450-5300 km s{sup –1}), with large [N II]/Hα ratios, above log(M {sub *}/M {sub ☉}) ∼ 10.9, with about two-thirds of the galaxies in this mass range exhibiting this component. Broad nuclear components near and above the Schechter mass are similarly prevalent above and below the main sequence of star-forming galaxies, and at z ∼ 1 and ∼2. The line ratios of the nuclear component are fit by excitation from active galactic nuclei (AGNs), or by a combination of shocks and photoionization. The incidence of the most massive galaxies with broad nuclear components is at least as large as that of AGNs identified by X-ray, optical, infrared, or radio indicators. The mass loading of the nuclear outflows is near unity. Our findings provide compelling evidence for powerful, high-duty cycle, AGN-driven outflows near the Schechter mass, and acting across the peak of cosmic galaxy formation.

  6. MASSIV: Mass Assembly Survey with SINFONI in VVDS. IV. Fundamental relations of star-forming galaxies at 1 < z < 1.6

    NASA Astrophysics Data System (ADS)

    Vergani, D.; Epinat, B.; Contini, T.; Tasca, L.; Tresse, L.; Amram, P.; Garilli, B.; Kissler-Patig, M.; Le Fèvre, O.; Moultaka, J.; Paioro, L.; Queyrel, J.; López-Sanjuan, C.

    2012-10-01

    Aims: How mass assembly occurs in galaxies and which process(es) contribute to this activity are among the most highly debated questions in galaxy formation and evolution theories. This has motivated our survey MASSIV (Mass Assembly Survey with SINFONI in VVDS) of 0.9 < z < 1.9 star-forming galaxies selected from the purely flux-limited VVDS redshift survey. Methods: We evaluate the characteristic size and stellar mass of 46 MASSIV galaxies at 1 < z < 1.6 and use the internal dynamics obtained with the SINFONI integral field spectrograph mounted at the Very Large Telescope, to derive the stellar mass-size-velocity relations. We use the Kennicutt-Schmidt formulation to estimate the gas content and compute its contribution to the total baryonic mass in MASSIV galaxies. Results: For the first time, we derive the relations between galaxy size, mass, and internal velocity, and the baryonic Tully-Fisher relation, from a statistically representative sample of star-forming galaxies at 1 < z < 1.6. We find a dynamical mass that agrees with those of rotating galaxies containing a gas fraction of ~ 20%, that is perfectly consistent with the content derived using the Kennicutt-Schmidt formulation and corresponds to the expected evolution. Non-rotating galaxies have more compact sizes for their stellar component, and are less massive than rotators, but do not have statistically different sizes for their gas-component. Discs of ionized gas have irregular, clumpy distributions, but the simplistic assumption of exponential profiles is verified. We measure a marginal evolution in the size-stellar mass and size-velocity relations in which discs become evenly smaller with cosmic time at fixed stellar mass or velocity, and are less massive at a given velocity than in the local Universe. This result is inconsistent with previous reports of an abnormal evolution in the galactic spin. The scatter in the Tully-Fisher relation is smaller when we introduce the S05 index, which we interpret

  7. Massive Spheroidal Galaxies: Nature and Evolution During 0.6

    NASA Astrophysics Data System (ADS)

    Rizer, Zachary; McIntosh, Daniel H.; Cook, Joshua; Kartaltepe, Jeyhan S.; Wuyts, Stijn; van der Wel, Arjen; Barro, Guillermo; Koekemoer, Anton M.; Conselice, Christopher; Bell, Eric F.; Kocevski, Dale; Koo, David C.; Giavalisco, Mauro

    2015-01-01

    Spheroidal galaxies are linked to the observed buildup of massive non-star-forming (quiescent) galaxies over cosmic time. Yet, it remains unclear whether the primary growth channel involves the formation of new bulge-dominated galaxies followed by the quenching of star formation (SF), or the cessation of star production preceded by the transformation from disk-dominated to spheroidal galaxies. Using a new comprehensive catalog of visual classifications based on the HST/WFC3 imaging from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), we study the nature and evolution of high-mass (Mstar>1e10 Msun) 'spheroids' (elliptical and bulge-dominated galaxies) over a wide redshift range (0.6galaxies. Using either rest-frame UVJ colors or total SF rates (IR + UV) when available, which we've verified yield similar selections in these fields, we find a clear increase in the fraction of high-mass galaxies that are quiescent spheroids with decreasing redshift, accompanied by a relatively constant low fraction (10-25%) of star-forming spheroids at z>1, and a possible drop to lower fractions at z<1. We find quantitatively similar results using spheroid samples defined solely or jointly by automatic (Sérsic n>2) selection. We find that as the high-mass galaxy population becomes more quenched, it also becomes more dominated by spheroids with very few quiescent disks (<10%) at any redshift. Taken together, these results are consistent with a scenario in which new spheroids were continuously added and subsequently quenched, and inconsistent with an evolutionary process that primarily added newly quenched disks. The actual picture likely includes contributions from multiple channels and requires detailed modeling to better constrain the relative

  8. THE CIRCUMGALACTIC MEDIUM OF MASSIVE GALAXIES AT z {approx} 3: A TEST FOR STELLAR FEEDBACK, GALACTIC OUTFLOWS, AND COLD STREAMS

    SciTech Connect

    Shen Sijing; Madau, Piero; Prochaska, J. Xavier; Guedes, Javiera; Mayer, Lucio; Wadsley, James

    2013-03-10

    We present new results on the kinematics, thermal and ionization state, and spatial distribution of metal-enriched gas in the circumgalactic medium (CGM) of massive galaxies at redshift {approx}3, using the Eris suite of cosmological hydrodynamic ''zoom-in'' simulations. The reference run adopts a blastwave scheme for supernova feedback that produces large-scale galactic outflows, a star formation recipe based on a high gas density threshold, metal-dependent radiative cooling, and a model for the diffusion of metals and thermal energy. The effect of the local UV radiation field is added in post-processing. The CGM (defined as all gas at R > 0.2 R{sub vir} = 10 kpc, where R{sub vir} is the virial radius) contains multiple phases having a wide range of physical conditions, with more than half of its heavy elements locked in a warm-hot component at T > 10{sup 5} K. Synthetic spectra, generated by drawing sightlines through the CGM, produce interstellar absorption-line strengths of Ly{alpha}, C II, C IV, Si II, and Si IV as a function of the galactocentric impact parameter (scaled to the virial radius) that are in broad agreement with those observed at high redshift by Steidel et al. The covering factor of absorbing material declines less rapidly with impact parameter for Ly{alpha} and C IV compared to C II, Si IV, and Si II, with Ly{alpha} remaining strong (W{sub Ly{alpha}} > 300 mA) to {approx}> 5 R{sub vir} = 250 kpc. Only about one third of all the gas within R{sub vir} is outflowing. The fraction of sightlines within one virial radius that intercept optically thick, N{sub H{sub I}}>10{sup 17.2} cm{sup -2} material is 27%, in agreement with recent observations by Rudie et al. Such optically thick absorption is shown to trace inflowing ''cold'' streams that penetrate deep inside the virial radius. The streams, enriched to metallicities above 0.01 solar by previous episodes of star formation in the main host and in nearby dwarfs, are the origin of strong (N{sub C

  9. The Circumgalactic Medium of Massive Galaxies at z ~ 3: A Test for Stellar Feedback, Galactic Outflows, and Cold Streams

    NASA Astrophysics Data System (ADS)

    Shen, Sijing; Madau, Piero; Guedes, Javiera; Mayer, Lucio; Prochaska, J. Xavier; Wadsley, James

    2013-03-01

    We present new results on the kinematics, thermal and ionization state, and spatial distribution of metal-enriched gas in the circumgalactic medium (CGM) of massive galaxies at redshift ~3, using the Eris suite of cosmological hydrodynamic "zoom-in" simulations. The reference run adopts a blastwave scheme for supernova feedback that produces large-scale galactic outflows, a star formation recipe based on a high gas density threshold, metal-dependent radiative cooling, and a model for the diffusion of metals and thermal energy. The effect of the local UV radiation field is added in post-processing. The CGM (defined as all gas at R > 0.2 R vir = 10 kpc, where R vir is the virial radius) contains multiple phases having a wide range of physical conditions, with more than half of its heavy elements locked in a warm-hot component at T > 105 K. Synthetic spectra, generated by drawing sightlines through the CGM, produce interstellar absorption-line strengths of Lyα, C II, C IV, Si II, and Si IV as a function of the galactocentric impact parameter (scaled to the virial radius) that are in broad agreement with those observed at high redshift by Steidel et al. The covering factor of absorbing material declines less rapidly with impact parameter for Lyα and C IV compared to C II, Si IV, and Si II, with Lyα remaining strong (W Lyα > 300 mÅ) to >~ 5 R vir = 250 kpc. Only about one third of all the gas within R vir is outflowing. The fraction of sightlines within one virial radius that intercept optically thick, N H I>1017.2 cm-2 material is 27%, in agreement with recent observations by Rudie et al. Such optically thick absorption is shown to trace inflowing "cold" streams that penetrate deep inside the virial radius. The streams, enriched to metallicities above 0.01 solar by previous episodes of star formation in the main host and in nearby dwarfs, are the origin of strong (N C II>1013 cm-2) C II absorption with a covering factor of 22% within R vir and 10% within 2 R vir

  10. The three-dimensional geometry and merger history of the massive galaxy cluster MACS J0358.8-2955

    NASA Astrophysics Data System (ADS)

    Hsu, Li-Yen; Ebeling, Harald; Richard, Johan

    2013-02-01

    We present results of a combined X-ray/optical analysis of the dynamics of the massive cluster MACS J0358.8-2955 (z = 0.428) based on observations with the Chandra X-ray Observatory, the Hubble Space Telescope and the Keck-I telescope on Mauna Kea. MACS J0358.8-2955 is found to be one of the most X-ray luminous clusters known at z > 0.3, featuring LX, bol( < r500) = 4.24 × 1045 erg s-1, kT = 9.55+ 0.58- 0.37 keV, M3Dgas( < r500) = (9.18 ± 1.45) × 1013 M⊙ and M3Dtot( < r500) = (1.12 ± 0.18) × 1015 M⊙. The system's high velocity dispersion of 1440+ 130- 110 km s- 1 (890 km s-1 when the correct relativistic equation is used), however, is inflated by infall along the line of sight, as the result of a complex merger of at least three subclusters. One collision proceeds close to head-on, while the second features a significant impact parameter. The temperature variations in the intracluster gas, two tentative cold fronts, the radial velocities measured for cluster galaxies and the small offsets between collisional and non-collisional cluster components all suggest that both merger events are observed close to core passage and along the axes that are greatly inclined with respect to the plane of the sky. A strong-lensing analysis of the system anchored upon three triple-image systems (two of which have spectroscopic redshifts) yields independent constraints on the mass distribution. For a gas fraction of 8.2 per cent, the resulting strong-lensing mass profile is in good agreement with our X-ray estimates, and the details of the mass distribution are fully consistent with our interpretation of the 3D merger history of this complex system. Underlining yet again the power of X-ray selection, our analysis also resolves earlier confusion about the contribution of the partly superimposed foreground cluster A 3192 (z = 0.168). Based on very faint X-ray emission detected by our Chandra observation and 16 concordant redshifts we identify A 3192 as two groups of galaxies

  11. SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems

    SciTech Connect

    Eisenstein, Daniel J.; Weinberg, David H.; Agol, Eric; Aihara, Hiroaki; Prieto, Carlos Allende; Anderson, Scott F.; Arns, James A.; Aubourg, Eric; Bailey, Stephen; Balbinot, Eduardo; Barkhouser, Robert; /Johns Hopkins U. /Michigan State U.

    2011-01-01

    Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. The Baryon Oscillation Spectroscopic Survey (BOSS) will measure redshifts of 1.5 million massive galaxies and Ly{alpha} forest spectra of 150,000 quasars, using the baryon acoustic oscillation (BAO) feature of large scale structure to obtain percent-level determinations of the distance scale and Hubble expansion rate at z < 0.7 and at z {approx} 2.5. SEGUE-2, a now-completed continuation of the Sloan Extension for Galactic Understanding and Exploration, measured medium-resolution (R = {lambda}/{Delta}{lambda} 1800) optical spectra of 118,000 stars in a variety of target categories, probing chemical evolution, stellar kinematics and substructure, and the mass profile of the dark matter halo from the solar neighborhood to distances of 100 kpc. APOGEE, the Apache Point Observatory Galactic Evolution Experiment, will obtain high-resolution (R {approx} 30,000), high signal-to-noise ratio (S/N {ge} 100 per resolution element), H-band (1.51 {micro}m < {lambda} < 1.70 {micro}m) spectra of 10{sup 5} evolved, late-type stars, measuring separate abundances for {approx} 15 elements per star and creating the first high-precision spectroscopic survey of all Galactic stellar populations (bulge, bar, disks, halo) with a uniform set of stellar tracers and spectral diagnostics. The Multi-object APO Radial Velocity Large-area Survey (MARVELS) will monitor radial velocities of more than 8000 FGK stars with the sensitivity and cadence (10-40 m s{sup -1}, {approx} 24 visits per star) needed to detect giant planets with periods up to two years, providing an unprecedented data set for understanding the formation and dynamical evolution of giant planet systems. As of January 2011, SDSS-III has obtained

  12. Using a Weak CN Spectral Feature as a Marker for Massive AGB Stars in the Andromeda Galaxy

    NASA Astrophysics Data System (ADS)

    Guhathakurta, Puragra; Kamath, Anika; Sales, Alyssa; Sarukkai, Atmika; Hays, Jon; PHAT Collaboration; SPLASH Collaboration

    2017-01-01

    The Panchromatic Hubble Andromeda Treasury (PHAT) survey has produced six-filter photometry at near-ultraviolet, optical and nearly infrared wavelengths (F275W, F336W, F475W, F814W, F110W and F160W) for over 100 million stars in the disk of the of the Andromeda galaxy (M31). As part of the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) survey, medium resolution (R ~ 2000) spectra covering the wavelength range 4500-9500A were obtained for over 5000 relatively bright stars from the PHAT source catalog using the Keck II 10-meter telescope and DEIMOS spectrograph. While searching for carbon stars in the spectroscopic data set, we discovered a rare population of stars that show a weak CN spectral absorption feature at ~7900A (much weaker than the CN feature in typical carbon stars) along with other spectral absorption features like TiO and the Ca triplet that are generally not present/visible in carbon star spectra but that are typical for normal stars with oxygen rich atmospheres. These 150 or so "weak CN" stars appear to be fairly localized in six-filter space (i.e., in various color-color and color-magnitude diagrams) but are generally offset from carbon stars. Comparison to PARSEC model stellar tracks indicates that these weak CN stars are probably massive (5-10 Msun) asymptotic giant branch (AGB) stars in a relatively short-lived core helium burning phase of their evolution. Careful spectroscopic analysis indicates that the details of the CN spectral feature are about 3-4x weaker in weak CN stars than in carbon stars. The kinematics of weak CN stars are similar to those of other young stars (e.g., massive main sequence stars) and reflect the well ordered rotation of M31's disk.This research project is funded in part by NASA/STScI and the National Science Foundation. Much of this work was carried out by high school students and undergraduates under the auspices of the Science Internship Program and LAMAT program at the University of

  13. Unveiling the Important Role of Groups in the Evolution of Massive Galaxies: Insights from an Infrared Passive Sequence at Intermediate Redshift

    NASA Astrophysics Data System (ADS)

    Wilman, D. J.; Pierini, D.; Tyler, K.; McGee, S. L.; Oemler, A., Jr.; Morris, S. L.; Balogh, M. L.; Bower, R. G.; Mulchaey, J. S.

    2008-06-01

    The most massive galaxies in the universe are also the oldest. To overturn this apparent contradiction with hierarchical growth models we focus on the group-scale halos that host most of these galaxies. Our z ~ 0.4 group sample is selected in redshift space from the CNOC2 redshift survey. A stellar mass-selected M*gtrsim 2 × 1010 M⊙ sample is constructed using IRAC observations. A sensitive mid-infrared (MIR) IRAC color is used to isolate passive galaxies. It produces a bimodal distribution, in which passive galaxies (highlighted by morphological early types) define a tight MIR color sequence (infrared passive sequence, IPS). This is due to stellar atmospheric emission from old stellar populations. Significantly offset from the IPS are galaxies where reemission by dust boosts emission at λobs = 8 μm. We term them infrared excess galaxies, whether star formation and/or AGN activity are present. They include all known morphological late types. Comparison with EW[O II] shows that MIR color is highly sensitive to low levels of activity and allows us to separate dusty active from passive galaxies at high stellar mass. The fraction of infrared excess galaxies, f(IRE) , drops with M*, such that f(IRE) = 0.5 at a "crossover mass" of Mcr ~ 1.3 × 1011 M⊙. Within our optically defined group sample there is a strong and consistent deficit in f(IRE) at all masses, but most clearly at M*gtrsim 1011 M⊙. Suppression of star formation must mainly occur in groups. In particular, the observed trend of f(IRE) with M* can be explained if suppression of M*gtrsim 1011 M⊙ galaxies occurs primarily in the group environment. This is confirmed using a mock galaxy catalog derived from the millenium simulation. In this way, the mass-dependent evolution in f(IRE) (downsizing) can be driven solely by structure growth in the universe, as more galaxies are accreted into group-sized halos with cosmic time.

  14. The VIMOS Public Extragalactic Redshift Survey (VIPERS):. A quiescent formation of massive red-sequence galaxies over the past 9 Gyr

    NASA Astrophysics Data System (ADS)

    Fritz, A.; Scodeggio, M.; Ilbert, O.; Bolzonella, M.; Davidzon, I.; Coupon, J.; Garilli, B.; Guzzo, L.; Zamorani, G.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bottini, D.; Branchini, E.; Cappi, A.; Cucciati, O.; De Lucia, G.; de la Torre, S.; Franzetti, P.; Fumana, M.; Granett, B. R.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Paioro, L.; Polletta, M.; Pollo, A.; Schlagenhaufer, H.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moscardini, L.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Phleps, S.; Wolk, M.

    2014-03-01

    We explore the evolution of the colour-magnitude relation (CMR) and luminosity function (LF) at 0.4 < z < 1.3 from the VIMOS Public Extragalactic Redshift Survey (VIPERS) using ~45 000 galaxies with precise spectroscopic redshifts down to i'AB < 22.5 over ~10.32 deg2 in two fields. From z = 0.5 to z = 1.3 the LF and CMR are well defined for different galaxy populations and M*B evolves by ~1.04(1.09) ± 0.06(0.10) mag for the total (red) galaxy sample. We compare different criteria for selecting early-type galaxies: (1) a fixed cut in rest-frame (U - V) colours, (2) an evolving cut in (U - V) colours, (3) a rest-frame (NUV - r') - (r' - K) colour selection, and (4) a spectral-energy-distribution classification. The completeness and contamination varies for the different methods and with redshift, but regardless of the method we measure a consistent evolution of the red-sequence (RS). Between 0.4 < z < 1.3 we find a moderate evolution of the RS intercept of Δ(U - V) = 0.28 ± 0.14 mag, favouring exponentially declining star formation (SF) histories with SF truncation at 1.7 ≤ z ≤ 2.3. Together with the rise in the number density of red galaxies by 0.64 dex since z = 1, this suggests a rapid build-up of massive galaxies (M⋆ > 1011 M⊙) and expeditious RS formation over a short period of ~1.5 Gyr starting before z = 1. This is supported by the detection of ongoing SF in early-type galaxies at 0.9 < z < 1.0, in contrast with the quiescent red stellar populations of early-type galaxies at 0.5 < z < 0.6. There is an increase in the observed CMR scatter with redshift, which is two times larger than observed in galaxy clusters and at variance with theoretical model predictions. We discuss possible physical mechanisms that support the observed evolution of the red galaxy population. Our findings point out that massive galaxies have experienced a sharp SF quenching at z ~ 1 with only limited additional merging. In contrast, less-massive galaxies experience a mix of SF

  15. UV-extended E-MILES stellar population models: young components in massive early-type galaxies

    NASA Astrophysics Data System (ADS)

    Vazdekis, A.; Koleva, M.; Ricciardelli, E.; Röck, B.; Falcón-Barroso, J.

    2016-12-01

    We present UV-extended E-MILES stellar population synthesis models covering the spectral range λλ 1680-50 000 Å at moderately high resolution. We employ the NGSL space-based stellar library to compute spectra of single-age, single-metallicity stellar populations in the wavelength range from 1680 to 3540 Å. These models represent a significant improvement in resolution and age/metallicity coverage over previous studies based on earlier space-based libraries. These model spectra were joined with those we computed in the visible using MILES, and other empirical libraries for redder wavelengths. The models span the metallicity range -1.79≤ [M/H]≤ +0.26 and ages above 30 Myr, for a suite of initial mass function types with varying slopes. We focus on the behaviour of colours, spectra and line-strength indices in the UV range as a function of relevant stellar population parameters. Whereas some indices strengthen with increasing age and metallicity, as most metallicity indicators in the visible, other indices peak around 3 Gyr for metal-rich stellar populations, such as Mg at 2800 Å. Our models provide reasonably good fits to the integrated colours and most line strengths of the stellar clusters of the Milky Way and Large Magellanic Cloud. Our full spectrum fits in the UV range for a representative set of early-type galaxies (ETGs) of varying mass yield age and metallicity estimates in very good agreement with those obtained in the optical range. The comparison of UV colours and line strengths of massive ETGs with our models reveals the presence of young stellar components, with ages in the range 0.1-0.5 Gyr and mass fractions 0.1-0.5 per cent, on the top of an old stellar population.

  16. Infrared Spectroscopy of a Massive Obscured Star Cluster in the Antennae Galaxies (NGC 4038/9) with NIRSPEC.

    PubMed

    Gilbert; Graham; McLean; Becklin; Figer; Larkin; Levenson; Teplitz; Wilcox

    2000-04-10

    We present infrared spectroscopy of the Antennae galaxies (NGC 4038/9) with the near-infrared spectrometer (NIRSPEC) at the W. M. Keck Observatory. We imaged the star clusters in the vicinity of the southern nucleus (NGC 4039) with 0&farcs;39 seeing in the K band using NIRSPEC's slit-viewing camera. The brightest star cluster revealed in the near-IR [MK&parl0;0&parr0; approximately -17.9] is insignificant optically but is coincident with the highest surface brightness peak in the mid-IR (12-18 µm) Infrared Space Observatory image presented by Mirabel et al. We obtained high signal-to-noise ratio 2.03-2.45 µm spectra of the nucleus and the obscured star cluster at R approximately 1900. The cluster is very young ( approximately 4 Myr), massive (M approximately 16x106 M middle dot in circle), and compact (with a density of approximately 115 M middle dot in circle pc-3 within a 32 pc half-light radius), assuming a Salpeter initial mass function (0.1-100 M middle dot in circle). Its hot stars have a radiation field characterized by Teff approximately 39,000 K, and they ionize a compact H ii region with ne approximately 104 cm-3. The stars are deeply embedded in gas and dust (AV approximately 9-10 mag), and their strong far-ultraviolet field powers a clumpy photodissociation region with densities nH greater, similar105 cm-3 on scales of approximately 200 pc, radiating LH21-0S&parl0;1&parr0;=9600 L middle dot in circle.

  17. A CENSUS OF MID-INFRARED-SELECTED ACTIVE GALACTIC NUCLEI IN MASSIVE GALAXY CLUSTERS AT 0 {approx}< z {approx}< 1.3

    SciTech Connect

    Tomczak, Adam R.; Tran, Kim-Vy H.; Saintonge, Amelie

    2011-09-01

    We conduct a deep mid-infrared (mid-IR) census of nine massive galaxy clusters at (0 < z < 1.3) with a total of {approx}1500 spectroscopically confirmed member galaxies using Spitzer/IRAC photometry and established mid-IR color selection techniques. Of the 949 cluster galaxies that are detected in at least three of the four IRAC channels at the {>=}3{sigma} level, we identify 12 that host mid-IR-selected active galactic nuclei (IR-AGNs). To compare the IR-AGNs across our redshift range, we define two complete samples of cluster galaxies: (1) optically selected members with rest-frame V{sub AB} magnitude < - 21.5 and (2) mid-IR-selected members brighter than (M*{sub 3.6} + 0.5), i.e., essentially a stellar mass cut. In both samples, we measure f{sub IR-AGN} {approx} 1% with a strong upper limit of {approx}3% at z < 1. This uniformly low IR-AGN fraction at z < 1 is surprising given that the fraction of 24 {mu}m sources in the same galaxy clusters is observed to increase by about a factor of four from z {approx} 0 to z {approx} 1; this indicates that most of the detected 24 {mu}m flux is due to star formation. Only in our single galaxy cluster at z = 1.24 is the IR-AGN fraction measurably higher at {approx}15% (all members; {approx}70% for late-types only). In agreement with recent studies, we find that the cluster IR-AGNs are predominantly hosted by late-type galaxies with blue optical colors, i.e., members with recent/ongoing star formation. The four brightest IR-AGNs are also X-ray sources; these IR+X-ray AGNs all lie outside the cluster core (R{sub proj} {approx}> 0.5 Mpc) and are hosted by highly morphologically disturbed members. Although our sample is limited, our results suggest that f{sub IR-AGN} in massive galaxy clusters is not strongly correlated with star formation at z < 1 and that IR-AGNs have a more prominent role at z {approx}> 1.

  18. The VIMOS Public Extragalactic Redshift Survey (VIPERS). A precise measurement of the galaxy stellar mass function and the abundance of massive galaxies at redshifts 0.5 < z < 1.3

    NASA Astrophysics Data System (ADS)

    Davidzon, I.; Bolzonella, M.; Coupon, J.; Ilbert, O.; Arnouts, S.; de la Torre, S.; Fritz, A.; De Lucia, G.; Iovino, A.; Granett, B. R.; Zamorani, G.; Guzzo, L.; Abbas, U.; Adami, C.; Bel, J.; Bottini, D.; Branchini, E.; Cappi, A.; Cucciati, O.; Franzetti, P.; Fumana, M.; Garilli, B.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Paioro, L.; Peacock, J. A.; Polletta, M.; Pollo, A.; Schlagenhaufer, H.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moscardini, L.; Moutard, T.; Nichol, R. C.; Percival, W. J.; Phleps, S.; Wolk, M.

    2013-10-01

    We measure the evolution of the galaxy stellar mass function from z = 1.3 to z = 0.5 using the first 53 608 redshifts of the ongoing VIMOS Public Extragalactic Survey (VIPERS). Thanks to its large volume and depth, VIPERS provides a detailed picture of the galaxy distribution at z ≃ 0.8, when the Universe was ≃7 Gyr old. We carefully estimate the uncertainties and systematic effects associated with the SED fitting procedure used to derive galaxy stellar masses. We estimate the galaxy stellar mass function at several epochs between z = 0.5 and 1.3, discussing the amount of cosmic variance affecting our estimate in detail. We find that Poisson noise and cosmic variance of the galaxy mass function in the VIPERS survey are comparable to the statistical uncertainties of large surveys in the local universe. VIPERS data allow us to determine with unprecedented accuracy the high-mass tail of the galaxy stellar mass function, which includes a significant number of galaxies that are too rare to detect with any of the past spectroscopic surveys. At the epochs sampled by VIPERS, massive galaxies had already assembled most of their stellar mass. We compare our results with both previous observations and theoretical models. We apply a photometric classification in the (U - V) rest-frame colour to compute the mass function of blue and red galaxies, finding evidence for the evolution of their contribution to the total number density budget: the transition mass above which red galaxies dominate is found to be about 1010.4 ℳ⊙ at z ≃ 0.55, and it evolves proportionally to (1 + z)3. We are able to separately trace the evolution of the number density of blue and red galaxies with masses above 1011.4 ℳ⊙, in a mass range barely studied in previous work. We find that for such high masses, red galaxies show a milder evolution with redshift, when compared to objects at lower masses. At the same time, we detect a population of similarly massive blue galaxies, which are no

  19. Morphologically Disturbed Massive Galaxies: Nature and Evolution During 0.6 < z < 2.5 in the CANDELS UDS and GOODS-S Fields

    NASA Astrophysics Data System (ADS)

    Cook, Joshua S.; McIntosh, Daniel H.; Rizer, Zachary; Kartaltepe, Jeyhan S.; Koekemoer, Anton M.; Lotz, Jennifer; Conselice, Christopher; Hopkins, Philip F.; Wuyts, Stijn; Peth, Michael; Barro, Guillermo; Candels Collaboration

    2015-01-01

    Merging is predicted to be an important process in the early and turbulent assembly of massive galaxies. These violent encounters heavily impact galaxy morphology and structure. As such, the evolution of morphologically disturbed systems may help constrain the relative importance of merging, the answer to which is largely debated especially at higher redshifts. Disagreements between studies however, may be attributed to the various methods used to identify merging galaxies such as visual or quantitative classifications based on different rest-frame wavelengths. Using a new comprehensive catalog of visual rest-frame optical classifications based on HST/WFC3+ACS imaging from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS), we compare the nature and evolution of merging and highly disturbed galaxy subsamples within the UDS and GOODS-S fields. We limit our sample for completeness to high-mass objects (Mstar > 1e10 Msun) with redshifts between 0.6 < z < 2.5. Most disturbed galaxies are star-forming and two-thirds have masses under 3e10 Msun. We note that one-third appear to be neither interacting nor merging, rather they are isolated and visually disk-like. Under the assumption that many disturbed or unusual morphologies are related to merging, we compare visually-selected subsamples to merger selections based on two popular quantitative methods (Gini-M20 and CAS). We find that all selections produce similar fractions across our redshift range, but the individual galaxies making up the respective fractions are often different. This may indicate that different classification methods are preferentially selecting objects undergoing either different processes such as major merging, minor merging and violent disk instabilities, or different stages of the same process.

  20. The halos of satellite galaxies: the companion of the massive elliptical lens SL2S J08544-0121

    NASA Astrophysics Data System (ADS)

    Suyu, S. H.; Halkola, A.

    2010-12-01

    Strong gravitational lensing by groups or clusters of galaxies provides a powerful technique to measure the dark matter properties of individual lens galaxies. We study in detail the mass distribution of the satellite lens galaxy in the group-scale lens SL2S J08544-0121 by modelling simultaneously the spatially extended surface brightness distribution of the source galaxy and the lens mass distribution using Markov chain Monte Carlo methods. In particular, we measure the dark matter halo size of the satellite lens galaxy to be 6.0+2.9-2.0 kpc with a fiducial velocity dispersion of 127+21-12 km s-1. This is the first time the size of an individual galaxy halo in a galaxy group has been measured using strong gravitational lensing without assumptions of mass following light. We verify the robustness of our halo size measurement using mock data resembling our lens system. Our measurement of the halo size is compatible with the estimated tidal radius of the satellite galaxy, suggesting that halos of galaxies in groups experience significant tidal stripping, a process that has been previously observed on galaxies in clusters. Our mass model of the satellite galaxy is elliptical with its major axis misaligned with that of the light by ~50°. The major axis of the total matter distribution is oriented more towards the centre of the host halo, exhibiting the radial alignment found in N-body simulations and observational studies of satellite galaxies. This misalignment between mass and light poses a significant challenge to modified Newtonian dynamics. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 10876.

  1. An extremely dense group of massive galaxies at the centre of the protocluster at z = 3.09 in the SSA22 field

    NASA Astrophysics Data System (ADS)

    Kubo, M.; Yamada, T.; Ichikawa, T.; Kajisawa, M.; Matsuda, Y.; Tanaka, I.; Umehata, H.

    2016-01-01

    We report the discovery of an extremely dense group of massive galaxies at the centre of the protocluster at z = 3.09 in the SSA22 field from near-infrared spectroscopy conducted with the multi-object infrared camera and spectrograph (MOIRCS) on the Subaru Telecope. The newly discovered group comprises seven galaxies confirmed at zspec ≈ 3.09 within 180 kpc, including five massive objects with the stellar masses larger than 1010.5 M⊙ and is associated with a bright submillimetre source SSA22-AzTEC14. The dynamical mass of the group estimated from the line-of-sight velocity dispersion of the members is Mdyn ˜ 1.6 ± 0.3 × 1013 M⊙. Such a dense group is expected to be very rare at high redshift, as we have found only a few comparable systems in large-volume cosmological simulations. Such rare groups in simulations are hosted in collapsed haloes with Mvir = 1013.4-1014.0 M⊙ and evolve into the brightest cluster galaxies (BCGs) of the most massive clusters at present. The observed AzTEC14 group at z = 3.09 is therefore very likely to be a proto-BCG in the multiple merger phase. The observed total stellar mass of the group is 5.8^{+5.1}_{-2.0}× 10^{11} M_{⊙}, which suggests that over half the stellar mass of its descendant had been formed by z = 3. Moreover, we have identified over two members for each of the four Lyα blobs (LABs) using our new spectroscopic data. This verifies our previous argument that many of the LABs in the SSA22 protocluster associated with multiple developed stellar components.

  2. Exclusion of canonical weakly interacting massive particles by joint analysis of Milky Way dwarf galaxies with data from the Fermi Gamma-Ray Space Telescope.

    PubMed

    Geringer-Sameth, Alex; Koushiappas, Savvas M

    2011-12-09

    Dwarf spheroidal galaxies are known to be excellent targets for the detection of annihilating dark matter. We present new limits on the annihilation cross section of weakly interacting massive particles based on the joint analysis of seven Milky Way dwarfs using a frequentist Neyman construction and Pass 7 data from the Fermi Gamma-Ray Space Telescope. We exclude generic weakly interacting massive particle candidates annihilating into bb with a mass less than 40 GeV that reproduce the observed relic abundance. To within 95% systematic errors on the dark matter distribution within the dwarfs, the mass lower limit can be as low as 19 GeV or as high as 240 GeV. For annihilation into τ+ τ-, these limits become 19, 13, and 80 GeV, respectively.

  3. Exclusion of Canonical Weakly Interacting Massive Particles by Joint Analysis of Milky Way Dwarf Galaxies with Data from the Fermi Gamma-Ray Space Telescope

    NASA Astrophysics Data System (ADS)

    Geringer-Sameth, Alex; Koushiappas, Savvas M.

    2011-12-01

    Dwarf spheroidal galaxies are known to be excellent targets for the detection of annihilating dark matter. We present new limits on the annihilation cross section of weakly interacting massive particles based on the joint analysis of seven Milky Way dwarfs using a frequentist Neyman construction and Pass 7 data from the Fermi Gamma-Ray Space Telescope. We exclude generic weakly interacting massive particle candidates annihilating into bb¯ with a mass less than 40 GeV that reproduce the observed relic abundance. To within 95% systematic errors on the dark matter distribution within the dwarfs, the mass lower limit can be as low as 19 GeV or as high as 240 GeV. For annihilation into τ+τ-, these limits become 19, 13, and 80 GeV, respectively.

  4. MERGERS AND STAR FORMATION: THE ENVIRONMENT AND STELLAR MASS GROWTH OF THE PROGENITORS OF ULTRA-MASSIVE GALAXIES SINCE Z = 2

    SciTech Connect

    Vulcani, Benedetta; Marchesini, Danilo; De Lucia, Gabriella; Muzzin, Adam; Stefanon, Mauro; Labbé, Ivo; Brammer, Gabriel B.; Le Fèvre, Olivier; Milvang-Jensen, Bo

    2016-01-10

    The growth of galaxies is a key problem in understanding the structure and evolution of the universe. Galaxies grow their stellar mass by a combination of star formation and mergers, with a relative importance that is redshift dependent. Theoretical models predict quantitatively different contributions from the two channels; measuring these from the data is a crucial constraint. Exploiting the UltraVISTA catalog and a unique sample of progenitors of local ultra-massive galaxies selected with an abundance matching approach, we quantify the role of the two mechanisms from z = 2 to 0. We also compare our results to two independent incarnations of semi-analytic models. At all redshifts, progenitors are found in a variety of environments, ranging from being isolated to having 5–10 companions with mass ratio at least 1:10 within a projected radius of 500 kpc. In models, progenitors have a systematically larger number of companions, entailing a larger mass growth for mergers than in observations, at all redshifts. Generally, in both observations and models, the inferred and the expected mass growth roughly agree, within the uncertainties. Overall, our analysis confirms the model predictions, showing how the growth history of massive galaxies is dominated by in situ star formation at z ∼ 2, both star formation and mergers at 1 < z < 2, and by mergers alone at z < 1. Nonetheless, detailed comparisons still point out tensions between the expected mass growth and our results, which might be due to either an incorrect progenitors-descendants selection, uncertainties on star-formation rate and mass estimates, or the adopted assumptions on merger rates.

  5. Identification of dusty massive stars in star-forming dwarf irregular galaxies in the Local Group with mid-IR photometry

    NASA Astrophysics Data System (ADS)

    Britavskiy, N. E.; Bonanos, A. Z.; Mehner, A.; Boyer, M. L.; McQuinn, K. B. W.

    2015-12-01

    Context. Increasing the statistics of spectroscopically confirmed evolved massive stars in the Local Group enables the investigation of the mass loss phenomena that occur in these stars in the late stages of their evolution. Aims: We aim to complete the census of luminous mid-IR sources in star-forming dwarf irregular (dIrr) galaxies of the Local Group. To achieve this we employed mid-IR photometric selection criteria to identify evolved massive stars, such as red supergiants (RSGs) and luminous blue variables (LBVs), by using the fact that these types of stars have infrared excess due to dust. Methods: The method is based on 3.6 μm and 4.5 μm photometry from archival Spitzer Space Telescope images of nearby galaxies. We applied our criteria to four dIrr galaxies: Pegasus, Phoenix, Sextans A, and WLM, selecting 79 point sources that we observed with the VLT/FORS2 spectrograph in multi-object spectroscopy mode. Results: We identified 13 RSGs, of which 6 are new discoveries, as well as two new emission line stars, and one candidate yellow supergiant. Among the other observed objects we identified carbon stars, foreground giants, and background objects, such as a quasar and an early-type galaxy that contaminate our survey. We use the results of our spectroscopic survey to revise the mid-IR and optical selection criteria for identifying RSGs from photometric measurements. The optical selection criteria are more efficient in separating extragalactic RSGs from foreground giants than mid-IR selection criteria, but the mid-IR selection criteria are useful for identifying dusty stars in the Local Group. This work serves as a basis for further investigation of the newly discovered dusty massive stars and their host galaxies. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 090.D-0009 and 091.D-0010.Appendix A is available in electronic form at http://www.aanda.org

  6. New Results from Chandra on the X-ray Emission from the Massive Black Hole in the Compact Starburst Galaxy Henize 2-10

    NASA Astrophysics Data System (ADS)

    Reines, Amy E.; Reynolds, Mark; Miller, Jon M.; Sivakoff, Gregory R.; Greene, Jenny E.; Hickox, Ryan C.; Johnson, Kelsey E.

    2017-01-01

    We present follow-up X-ray observations of the candidate massive black hole (BH) in the nucleus of the low-mass, compact starburst galaxy Henize 2-10. Using new high-resolution observations from the Chandra X-ray Observatory totaling 200 ks in duration, as well as archival Chandra observations from 2001, we demonstrate the presence of a previously unidentified X-ray point source that is spatially coincident with the known nuclear radio source in Henize 2-10 (i.e., the massive BH). We show that the hard X-ray emission previously identified in the 2001 observation is dominated by a source that is distinct from the nucleus, with the properties expected for a high-mass X-ray binary. The X-ray luminosity of the nuclear source suggests the massive BH is radiating significantly below its Eddington limit, and the soft spectrum resembles other weakly accreting massive BHs including Sagittarius A*. Analysis of the X-ray light curve of the nuclear source reveals the tentative detection of a ~9-hour periodicity, although additional observations are required to confirm this result. Our study highlights the need for sensitive high-resolution X-ray observations to probe low-level accretion, which is the dominant mode of BH activity throughout the Universe.

  7. The Sloan Lens ACS Survey. I. A Large Spectroscopically Selected Sample of Massive Early-Type Lens Galaxies

    NASA Technical Reports Server (NTRS)

    Bolton, Adam S.; Burles, Scott; Koopmans, Leon V. E.; Treu, Tommaso; Moustakas, Leonidas A.

    2006-01-01

    The Sloan Lens ACS (SLACS) Survey is an efficient Hubble Space Telescope (HST) Snapshot imaging survey for new galaxy-scale strong gravitational lenses. The targeted lens candidates are selected spectroscopically from the Sloan Digital Sky Survey (SDSS) database of galaxy spectra for having multiple nebular emission lines at a redshift significantly higher than that of the SDSS target galaxy. The SLACS survey is optimized to detect bright early-type lens galaxies with faint lensed sources in order to increase the sample of known gravitational lenses suitable for detailed lensing, photometric, and dynamical modeling. In this paper, the first in a series on the current results of our HST Cycle 13 imaging survey, we present a catalog of 19 newly discovered gravitational lenses, along with nine other observed candidate systems that are either possible lenses, nonlenses, or nondetections. The survey efficiency is thus >=68%. We also present Gemini 8 m and Magellan 6.5 m integral-field spectroscopic data for nine of the SLACS targets, which further support the lensing interpretation. A new method for the effective subtraction of foreground galaxy images to reveal faint background features is presented. We show that the SLACS lens galaxies have colors and ellipticities typical of the spectroscopic parent sample from which they are drawn (SDSS luminous red galaxies and quiescent MAIN sample galaxies), but are somewhat brighter and more centrally concentrated. Several explanations for the latter bias are suggested. The SLACS survey provides the first statistically significant and homogeneously selected sample of bright early-type lens galaxies, furnishing a powerful probe of the structure of early-type galaxies within the half-light radius. The high confirmation rate of lenses in the SLACS survey suggests consideration of spectroscopic lens discovery as an explicit science goal of future spectroscopic galaxy surveys.

  8. Constraining the Merging History of Massive Galaxies Since Redshift 3 Using Close Pairs. I. Major Pairs from Candels and the SDSS

    NASA Astrophysics Data System (ADS)

    Mantha, Kameswara Bharadwaj; McIntosh, Daniel H.; Brennan, Ryan; Cook, Joshua; Kodra, Dritan; Newman, Jeffrey; Somerville, Rachel S.; Barro, Guillermo; Behroozi, Peter; Conselice, Christopher; Dekel, Avishai; Faber, Sandra M.; Closson Ferguson, Henry; Finkelstein, Steven L.; Fontana, Adriano; Galametz, Audrey; Perez-Gonzalez, Pablo; Grogin, Norman A.; Guo, Yicheng; Hathi, Nimish P.; Hopkins, Philip F.; Kartaltepe, Jeyhan S.; Kocevski, Dale; Koekemoer, Anton M.; Koo, David C.; Lee, Seong-Kook; Lotz, Jennifer M.; Lucas, Ray A.; Nayyeri, Hooshang; Peth, Michael; Pforr, Janine; Primack, Joel R.; Santini, Paola; Simmons, Brooke D.; Stefanon, Mauro; Straughn, Amber; Snyder, Gregory F.; Wuyts, Stijn

    2017-01-01

    Major galaxy-galaxy merging can play an important role in the history of massive galaxies (stellar masses > 2E10 Msun) over cosmic time. An important way to measure the impact of major merging is to study close pairs of galaxies stellar mass or flux ratios between 1 and 4. We improve on the best recent efforts by probing merging of lower mass galaxies, anchoring evolutionary trends from five Hubble Space Telescope Legacy fields in the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) to the nearby universe using Sloan Digital Sky Survey (SDSS) to measure the fraction of massive galaxies in such pairs during six epochs spanning 01.5. This implies that major merging may not be as important at high redshifts as previously thought, merger timescales may not be fully understood, or we may be missing evidence of mergers at z~2-3 owing to CANDELS selections effects. Next, we will analyze pair fractions and merging timescales within realistic mocks of CANDELS from state of the art Semi-Analytic Model (SAM) to better understand and calibrate our empirical results.

  9. Unveiling the Monsters: Characterization of Ultra-massive Galaxies in the Early Universe with IRAC Mapping of the NMBS-II/CFHTLS Fields

    NASA Astrophysics Data System (ADS)

    Marchesini, Danilo

    Observations of massive galaxies and their evolution with cosmic time place strong constraints on the physical processes of galaxy formation. Although substantial data have been collected on galaxies with masses log(Mstar/Msun)~11.2 out to z~4-5 from the recent myriad of ground-based near-infrared (NIR) surveys, very little is known about the evolution of the most massive (log(Mstar/Msun)>11.4) galaxies in the universe. At the tip of the Schechter function, their space density is estimated to be 30x lower than log (Mstar/Msun)=11 galaxies and hence only a few have been found, even in the widest-field surveys. We recently undertook the NMBS-II survey, a wide-field NIR medium-band survey designed to accurately characterize the stellar mass function, number density, stellar population and clustering properties of the most massive galaxies out to z=3. The NMBSII uses a set of five medium-bandwidth NIR filters to provide precise photometric redshifts and well-sampled spectral energy distributions (SEDs) of galaxies at z>1.5. The primary survey fields of the NMBS-II are the CFHTLS-deep fields; however, presently only 60% of these fields have IRAC coverage. The IRAC data are essential for accurately measuring photometric redshifts and stellar masses of the high-redshift population. IRAC data are also critical for separating the red quiescent from the red, dusty star-forming galaxies at z>0.8. In Cycle 10 (12/2013-10/2014), the PI Marchesini was awarded 22 hours of Spitzer time to complete the IRAC coverage of the NMBS-II fields, for a total area of 5.4 sq. deg. over 7 independent lines of sight. This proposal describes a program consisting of three main components. First, the newly acquired IRAC data at 3.6 and 4.5 micron awarded to the PI to complete the IRAC coverage of the NMBS-II fields will be reduced. Second, the addition of the Spitzer-IRAC and MIPS photometry to the NMBS-II K-selected catalogs will be completed. Third, a unique sample of ~300 ultra-massive

  10. B2 1637+29, a massive radio galaxy probing a poor but gas-rich group

    SciTech Connect

    De Ruiter, H.R.; Parma, P.; Fanti, R.; Ekers, R.D.

    1988-06-01

    New VLA and CCD observations of the radio source B2 1637+29, a member of the faint B2 sample of low-luminosity radio galaxies, are reported. The environment of the galaxy is discussed, and a description of the radio source morphology is given. The CCD image reveals that the optical counterpart is a double galaxy with radio jets emanating from the nucleus of the brighter of the two galaxies. It is shown that the galaxy is the dominant member of a poor group of galaxies, and it is argued that it moves with an average velocity of a few hundred km/s with respect to an intergalactic gas cloud with mass of 10 to the 13th solar or more. The relevance of the enviroment of the radio galaxy to the source morphology is discussed, and an explanation for the highly peculiar features, such as the undulation in the radio tail and the difference in both length and brightness of the main and counter jet, is proposed. 32 references.

  11. Resolved H I imaging of a population of massive H I-rich galaxies with suppressed star formation

    SciTech Connect

    Lemonias, Jenna J.; Schiminovich, David; Catinella, Barbara; Heckman, Timothy M.; Moran, Sean M.

    2014-07-20

    Despite the existence of well-defined relationships between cold gas and star formation, there is evidence that some galaxies contain large amounts of H I that do not form stars efficiently. By systematically assessing the link between H I and star formation within a sample of galaxies with extremely high H I masses (log M{sub H{sub I}}/M{sub ☉} > 10), we uncover a population of galaxies with an unexpected combination of high H I masses and low specific star formation rates that exists primarily at stellar masses greater than log M{sub *}/M{sub ☉} ∼ 10.5. We obtained H I maps of 20 galaxies in this population to understand the distribution of the H I and the physical conditions in the galaxies that could be suppressing star formation in the presence of large quantities of H I. We find that all of the galaxies we observed have low H I surface densities in the range in which inefficient star formation is common. The low H I surface densities are likely the main cause of the low specific star formation rates, but there is also some evidence that active galactic nuclei or bulges contribute to the suppression of star formation. The sample's agreement with the global star formation law highlights its usefulness as a tool for understanding galaxies that do not always follow expected relationships.

  12. Pathways to quiescence: SHARDS view on the star formation histories of massive quiescent galaxies at 1.0 < z < 1.5

    NASA Astrophysics Data System (ADS)

    Domínguez Sánchez, Helena; Pérez-González, Pablo G.; Esquej, Pilar; Eliche-Moral, M. Carmen; Barro, Guillermo; Cava, Antonio; Koekemoer, Anton M.; Alcalde Pampliega, Belén; Alonso Herrero, Almudena; Bruzual, Gustavo; Cardiel, Nicolás; Cenarro, Javier; Ceverino, Daniel; Charlot, Stéphane; Hernán Caballero, Antonio

    2016-04-01

    We present star formation histories (SFHs) for a sample of 104 massive (stellar mass M > 1010 M⊙) quiescent galaxies (MQGs) at z = 1.0-1.5 from the analysis of spectrophotometric data from the Survey for High-z Absorption Red and Dead Sources (SHARDS) and HST/WFC3 G102 and G141 surveys of the GOODS-North field, jointly with broad-band observations from ultraviolet (UV) to far-infrared (far-IR). The sample is constructed on the basis of rest-frame UVJ colours and specific star formation rates (sSFRs = SFR/Mass). The spectral energy distributions (SEDs) of each galaxy are compared to models assuming a delayed exponentially declining SFH. A Monte Carlo algorithm characterizes the degeneracies, which we are able to break taking advantage of the SHARDS data resolution, by measuring indices such as MgUV and D4000. The population of MQGs shows a duality in their properties. The sample is dominated (85 per cent) by galaxies with young mass-weighted ages, overline{t_M} < 2 Gyr, short star formation time-scales, <τ> ˜ 60-200 Myr, and masses log(M/M⊙) ˜ 10.5. There is an older population (15 per cent) with overline{t_M} = 2-4 Gyr, longer star formation time-scales, <τ> ˜ 400 Myr, and larger masses, log(M/M⊙) ˜ 10.7. The SFHs of our MQGs are consistent with the slope and the location of the main sequence of star-forming galaxies at z > 1.0, when our galaxies were 0.5-1.0 Gyr old. According to these SFHs, all the MQGs experienced a luminous infrared galaxy phase that lasts for ˜500 Myr, and half of them an ultraluminous infrared galaxy phase for ˜100 Myr. We find that the MQG population is almost assembled at z ˜ 1, and continues evolving passively with few additions to the population.

  13. Galaxy Formation with Self-Consistently Modeled Stars and Massive Black Holes. I: Feedback-Regulated Star Formation and Black Hole Growth

    SciTech Connect

    Kim, Ji-hoon; Wise, John H.; Alvarez, Marcelo A.; Abel, Tom; /KIPAC, Menlo Park /Stanford U., Phys. Dept.

    2011-11-04

    There is mounting evidence for the coevolution of galaxies and their embedded massive black holes (MBHs) in a hierarchical structure formation paradigm. To tackle the nonlinear processes of galaxy-MBH interaction, we describe a self-consistent numerical framework which incorporates both galaxies and MBHs. The high-resolution adaptive mesh refinement (AMR) code Enzo is modified to model the formation and feedback of molecular clouds at their characteristic scale of 15.2 pc and the accretion of gas onto an MBH. Two major channels of MBH feedback, radiative feedback (X-ray photons followed through full three-dimensional adaptive ray tracing) and mechanical feedback (bipolar jets resolved in high-resolution AMR), are employed. We investigate the coevolution of a 9.2 x 10{sup 11} M {circle_dot} galactic halo and its 10{sup 5} {circle_dot} M embedded MBH at redshift 3 in a cosmological CDM simulation. The MBH feedback heats the surrounding interstellar medium (ISM) up to 10{sup 6} K through photoionization and Compton heating and locally suppresses star formation in the galactic inner core. The feedback considerably changes the stellar distribution there. This new channel of feedback from a slowly growing MBH is particularly interesting because it is only locally dominant and does not require the heating of gas globally on the disk. The MBH also self-regulates its growth by keeping the surrounding ISM hot for an extended period of time.

  14. The mass of high-z massive galaxy cluster, SPT-CL J2106-5844 using weak-lensing analysis with HST observations

    NASA Astrophysics Data System (ADS)

    Kim, Jinhyub; Jee, James; Ko, Jongwan

    2017-01-01

    We present a weak-lensing analysis of the galaxy cluster SPT-CL J2106-5844 at z~1.132 using images from the Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) on-board on the Hubble Space Telescope (HST). This cluster discovered in the South Pole Telescope Sunyaev-Zel’dovich (SPT-SZ) survey is known to be the most massive system at z > 1 in the survey. Within the current ΛCDM hierarchical structure formation paradigm, the mass of the cluster at such a high redshift inferred by SZ, X-ray, and galaxy velocity dispersion data is somewhat unusual. The previous mass estimates, however, rely on assumptions on the dynamical state of the system, which may become questionable when the universe was young (about 40% of the current age). In this work, we present the first weak-lensing mass estimates of this interesting cluster. We describe how we derive a mass from the HST/ACS and HST/WFC3 deep imaging data and show a two-dimensional mass reconstruction. We find that the mass distribution of the cluster is unimodal with a centroid consistent (~1σ) with both galaxy luminosity and number density distributions. Based on tangential shear fitting with an NFW halo assumption, our weak-lensing mass estimates agree well with the previous estimates.

  15. On the Menu: Preferential Feeding Mechanisms for Super Massive Black Holes in Milky Way-Size Galaxies

    NASA Astrophysics Data System (ADS)

    Sanchez, N. Nicole; Bellovary, Jillian M.; Holley-Bockelmann, Kelly

    2015-08-01

    Using cosmological hydrodynamic simulations of Milky Way-type Galaxies, we explore the effect of accreted gas as feeding mechanisms for supermassive black holes. By examining two of these galaxies with differing merger histories, one characterized by several major mergers and the other with a quiescent history, we can examine the importance of merger history on black hole accretion. This study is an extension of Bellovary et. al. 2013, which did a similar study analyzing the accretion of high mass, high redshift galaxies and their central black holes. Bellovary found that the gas accreted by the central black holes was proportional to that accreted by the host galaxy. Contrary to the previous study's results, we've found that while a galaxy with a quiescent history will still have a black hole mirroring the accretion of its host, a galaxy with an active merger history has a central black hole that is preferentially fueled by gas accreted through mergers. We look to the the angular momentum of the accreted gas in these Milky Way analogs to develop a clearer picture of the mechanisms best fueling their central SMBHs.

  16. Boosted Tidal Disruption by Massive Black Hole Binaries During Galaxy Mergers from the View of N-Body Simulation

    NASA Astrophysics Data System (ADS)

    Li, Shuo; Liu, F. K.; Berczik, Peter; Spurzem, Rainer

    2017-01-01

    Supermassive black hole binaries (SMBHBs) are productions of the hierarchical galaxy formation model. There are many close connections between a central SMBH and its host galaxy because the former plays very important roles on galaxy formation and evolution. For this reason, the evolution of SMBHBs in merging galaxies is a fundamental challenge. Since there are many discussions about SMBHB evolution in a gas-rich environment, we focus on the quiescent galaxy, using tidal disruption (TD) as a diagnostic tool. Our study is based on a series of numerical, large particle number, direct N-body simulations for dry major mergers. According to the simulation results, the evolution can be divided into three phases. In phase I, the TD rate for two well separated SMBHs in a merging system is similar to that for a single SMBH in an isolated galaxy. After two SMBHs approach close enough to form a bound binary in phase II, the disruption rate can be enhanced by ∼2 orders of magnitude within a short time. This “boosted” disruption stage finishes after the SMBHB evolves to a compact binary system in phase III, corresponding to a reduction in disruption rate back to a level of a few times higher than in phase I. We also discuss how to correctly extrapolate our N-body simulation results to reality, and the implications of our results to observations.

  17. Massive black hole and gas dynamics in mergers of galaxy nuclei - II. Black hole sinking in star-forming nuclear discs

    NASA Astrophysics Data System (ADS)

    Lupi, Alessandro; Haardt, Francesco; Dotti, Massimo; Colpi, Monica

    2015-11-01

    Mergers of gas-rich galaxies are key events in the hierarchical built-up of cosmic structures, and can lead to the formation of massive black hole binaries. By means of high-resolution hydrodynamical simulations we consider the late stages of a gas-rich major merger, detailing the dynamics of two circumnuclear discs, and of the hosted massive black holes during their pairing phase. During the merger gas clumps with masses of a fraction of the black hole mass form because of fragmentation. Such high-density gas is very effective in forming stars, and the most massive clumps can substantially perturb the black hole orbits. After ˜10 Myr from the start of the merger a gravitationally bound black hole binary forms at a separation of a few parsecs, and soon after, the separation falls below our resolution limit of 0.39 pc. At the time of binary formation the original discs are almost completely disrupted because of SNa feedback, while on pc scales the residual gas settles in a circumbinary disc with mass ˜ 105 M⊙. We also test that binary dynamics is robust against the details of the SNa feedback employed in the simulations, while gas dynamics is not. We finally highlight the importance of the SNa time-scale on our results.

  18. Hydrodynamical simulations of realistic massive cluster populations

    NASA Astrophysics Data System (ADS)

    Barnes, David J.; Henson, Monique A.; Kay, Scott T.; McCarthy, Ian G.; Bahe, Yannick M.; Eagle Collaboration

    2015-09-01

    Galaxy clusters are seeded by density fluctuations in the early Universe and grow via hierarchical collapse to become the most massive virialised objects we observed today. They are powerful probes that study both cosmology and astrophysical processes. Their internal structure at the current epoch is the result of a non-trivial interplay between gravitational collapse and the energy fed into the intra-cluster medium (ICM) by star formation and active galactic nuclei (AGN). These processes shape the ICM during its formation at high redshift, but current observations of galaxy clusters are limited to z<0.5. The resolution and sensitivity of textit{Athena+} will allow it to study galaxy clusters in unprecedented detail. It will constrain cluster properties, such as its entropy, temperature and gas fraction, out to z˜2, enabling it to investigate the progenitors of today's massive clusters and observing the evolution of the properties of the ICM for the first time. Athena+ will produce a significant change in our understanding of the formation of galaxy clusters. Recently the theoretical modelling of clusters has advanced significantly and issues, such as the 'cooling catastophea', have been overcome by including feedback from star formation and AGN. We present the MAssive ClusterS and Intercluster Structures (MACSIS) project. The MACSIS project is a representative sample of 390 of galaxy clusters, with M_{FOF} > 10(15} M_{⊙) , re-simulated using the cosmo-OWLS model (Le Brun et al. 2014, McCarthy et al. in prep.) to extend it to the most massive and rarest objects. We demonstrate that this sample reproduces the scaling relations, with intrinsic scatter, observed with current instruments at low redshift. Under the hierarchical paradigm, the progenitors of these systems will be the first objects to collapse at high redshift and we examine to z=2 how the scaling relations of these massive objects evolve with redshift. Finally, we investigate methods of defining a

  19. Hubble Frontier Fields: a high-precision strong-lensing analysis of the massive galaxy cluster Abell 2744 using ˜180 multiple images

    NASA Astrophysics Data System (ADS)

    Jauzac, M.; Richard, J.; Jullo, E.; Clément, B.; Limousin, M.; Kneib, J.-P.; Ebeling, H.; Natarajan, P.; Rodney, S.; Atek, H.; Massey, R.; Eckert, D.; Egami, E.; Rexroth, M.

    2015-09-01

    We present a high-precision mass model of galaxy cluster Abell 2744, based on a strong gravitational-lensing analysis of the Hubble Space Telescope Frontier Fields (HFF) imaging data, which now include both Advanced Camera for Surveys and Wide Field Camera 3 observations to the final depth. Taking advantage of the unprecedented depth of the visible and near-infrared data, we identify 34 new multiply imaged galaxies, bringing the total to 61, comprising 181 individual lensed images. In the process, we correct previous erroneous identifications and positions of multiple systems in the northern part of the cluster core. With the LENSTOOL software and the new sets of multiple images, we model the cluster using two cluster-scale dark matter haloes plus galaxy-scale haloes for the cluster members. Our best-fitting model predicts image positions with an rms error of 0.79 arcsec, which constitutes an improvement by almost a factor of 2 over previous parametric models of this cluster. We measure the total projected mass inside a 200 kpc aperture as (2.162 ± 0.005) × 1014 M⊙, thus reaching 1 per cent level precision for the second time, following the recent HFF measurement of MACSJ0416.1-2403. Importantly, the higher quality of the mass model translates into an overall improvement by a factor of 4 of the derived magnification factor. Together with our previous HFF gravitational lensing analysis, this work demonstrates that the HFF data enables high-precision mass measurements for massive galaxy clusters and the derivation of robust magnification maps to probe the early Universe.

  20. Evolution of the dust emission of massive galaxies up to z = 4 and constraints on their dominant mode of star formation

    NASA Astrophysics Data System (ADS)

    Béthermin, Matthieu; Daddi, Emanuele; Magdis, Georgios; Lagos, Claudia; Sargent, Mark; Albrecht, Marcus; Aussel, Hervé; Bertoldi, Frank; Buat, Véronique; Galametz, Maud; Heinis, Sébastien; Ilbert, Olivier; Karim, Alexander; Koekemoer, Anton; Lacey, Cedric; Le Floc'h, Emeric; Navarrete, Felipe; Pannella, Maurilio; Schreiber, Corentin; Smolčić, Vernesa; Symeonidis, Myrto; Viero, Marco

    2015-01-01

    We aim to measure the average dust and molecular gas content of massive star-forming galaxies (>3 × 1010M⊙) up to z = 4 in the COSMOS field to determine if the intense star formation observed at high redshift is induced by major mergers or is caused by large gas reservoirs. Firstly, we measured the evolution of the average spectral energy distributions as a function of redshift using a stacking analysis of Spitzer, Herschel, LABOCA, and AzTEC data for two samples of galaxies: normal star-forming objects and strong starbursts, as defined by their distance to the main sequence. We found that the mean intensity of the radiation field ⟨ U ⟩ heating the dust (strongly correlated with dust temperature) increases with increasing redshift up to z = 4 in main-sequence galaxies. We can reproduce this evolution with simple models that account for the decrease in the gas metallicity with redshift. No evolution of ⟨ U ⟩ with redshift is found in strong starbursts. We then deduced the evolution of the molecular gas fraction (defined here as Mmol/ (Mmol + M⋆)) with redshift and found a similar, steeply increasing trend for both samples. At z ~ 4, this fraction reaches ~60%. The average position of the main-sequence galaxies is on the locus of the local, normal star-forming disks in the integrated Schmidt-Kennicutt diagram (star formation rate versus mass of molecular gas), suggesting that the bulk of the star formation up to z = 4 is dominated by secular processes. Appendices are available in electronic form at http://www.aanda.org

  1. The Massive and Distant Clusters of WISE Survey (MaDCoWS): Stellar mass fractions in a sample of infrared-selected galaxy clusters at z~1

    NASA Astrophysics Data System (ADS)

    Decker, Bandon; Brodwin, Mark

    2017-01-01

    Galaxy clusters are the largest gravitationally bound objects in the universe. In addition to being interesting objects in their own right, they are excellent laboratories in which to study galaxy evolution and the properties and abundance of galaxy clusters provide important tests for cosmology. The Massive and Distant Clusters of WISE Survey (MaDCoWS) is a high-redshift (z~1) survey that selects galaxy clusters in the infrared over nearly the full extragalactic sky using the Wide-field Infrared Survey Explorer (WISE) AllWISE data release. We have measured Sunyaev-Zel'dovich (SZ) masses for twelve of the MaDCoWS clusters lying in the range 0.9 < z <1.3 using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and used follow-up Spitzer/IRAC rest-frame near-infrared observations to measure the stellar mass of these clusters. With these data, we have measured the stellar mass fraction, f_star, and it's relation to total mass for a sample of infrared-selected clusters at z~1. We repeated our analysis of stellar mass fraction on a sample of SZ-selected clusters from the South Pole Telescope (SPT)-SZ survey that lie in a comparable range of mass and redshift to our MaDCoWS clusters to compare the selection methods. We found no significant difference in the trend of stellar mass fraction-to-total mass between infrared and radio selections. Comparing to similar measurements in the local Universe, we find no evidence of strong evolution in the trend over the last 8 Gyr.

  2. Les galaxies les plus lointaines: des elliptiques massives en pleine formation d'étoiles et de trous noirs

    NASA Astrophysics Data System (ADS)

    Rocca-Volmerange, Brigitte

    2016-08-01

    The most distant galaxies discovered at z>4 by the telescopes Herschel +Spitzer + HST, surprisingly appear as monsters compared to our Galaxy, with luminosities increasing with z. Younger in the space-time universe, they could be of low mass at high z , hard to detect and furtherly growing by a classical hierarchical merging process. However using the spectral evolutionary synthesis on the continuous UV to far-IR energy distribution with the help of the code Pegase.3, three distinct components are identified: i) the redshifted 1-2 microns peak, typical of a "passive" elliptical galaxy ii) a star formation episode iii) an AGN torus component more or less active. Moreover the cumulated supernova mass allows to estimate the stellar black hole mass of 109 solar masses, of the same order as supermassive black holes (Rocca-Volmerange et al, 2013, 2015, Drouart et al, 2016). These results, associated with the recent discoveries by the telescopes ALMA and MUSE, give a new view on the mass of primeval galaxies, on the AGN-star formation link, on the debated formation of elliptical galaxies and even on the re-ionization of the early universe.

  3. THE RELATIVE ABUNDANCE OF COMPACT AND NORMAL MASSIVE EARLY-TYPE GALAXIES AND ITS EVOLUTION FROM REDSHIFT z {approx} 2 TO THE PRESENT

    SciTech Connect

    Cassata, P.; Giavalisco, M.; Guo Yicheng; Salimbeni, S.; Renzini, A.; Ferguson, H.; Koekemoer, A. M.; Grogin, N. A.; Dahlen, T.; Lotz, J. M.; Scarlata, C.; Conselice, C. J.; Dickinson, M.; Lin Lihwai

    2011-12-10

    We report on the evolution of the number density and size of early-type galaxies (ETGs) from z {approx} 2 to z {approx} 0. We select a sample of 563 massive (M > 10{sup 10} M{sub Sun }), passively evolving (specific star formation rate <10{sup -2} Gyr{sup -1}), and morphologically spheroidal galaxies at 0 < z < 2.5, using the panchromatic photometry and spectroscopic redshifts available in the Great Observatories Origins Deep Surveys fields. We combine Advanced Camera for Surveys and Wide Field Camera 3 Hubble Space Telescope images to study the morphology of our galaxies in their optical rest frame in the entire 0 < z < 2.5 range. We find that throughout the explored redshift range the passive galaxies selected with our criteria have weak morphological K-correction, with size being slightly smaller in the optical than in the UV rest frame (by {approx}20% and {approx}10% at z > 1.2 and z < 1.2, respectively). We measure a significant evolution of the mass-size relation of ETGs, with a fractional increment that is almost independent of the stellar mass. ETGs formed at z > 1 appear to be preferentially small, and the evolution of the mass-size relation at z < 1 is driven by both the continuous size growth of the compact galaxies and the appearance of new ETGs with large sizes. We also find that the number density of all passive ETGs increases rapidly, by a factor of five, from z {approx} 2 to z {approx} 1, and then more mildly by another factor of 1.5 from z {approx} 1 to z {approx} 0. We interpret these results as evidence that the bulk of the ETGs are formed at 1 < z < 3 through a mechanism that leaves very compact remnants. At z < 1 the compact ETGs grow gradually in size, becoming normal-size galaxies, and at the same time new ETGs with normal-large sizes are formed.

  4. The Relative Abundance of Compact and Normal Massive Early-type Galaxies and Its Evolution from Redshift z ~ 2 to the Present

    NASA Astrophysics Data System (ADS)

    Cassata, P.; Giavalisco, M.; Guo, Yicheng; Renzini, A.; Ferguson, H.; Koekemoer, A. M.; Salimbeni, S.; Scarlata, C.; Grogin, N. A.; Conselice, C. J.; Dahlen, T.; Lotz, J. M.; Dickinson, M.; Lin, Lihwai

    2011-12-01

    We report on the evolution of the number density and size of early-type galaxies (ETGs) from z ~ 2 to z ~ 0. We select a sample of 563 massive (M > 1010 M ⊙), passively evolving (specific star formation rate <10-2 Gyr-1), and morphologically spheroidal galaxies at 0 < z < 2.5, using the panchromatic photometry and spectroscopic redshifts available in the Great Observatories Origins Deep Surveys fields. We combine Advanced Camera for Surveys and Wide Field Camera 3 Hubble Space Telescope images to study the morphology of our galaxies in their optical rest frame in the entire 0 < z < 2.5 range. We find that throughout the explored redshift range the passive galaxies selected with our criteria have weak morphological K-correction, with size being slightly smaller in the optical than in the UV rest frame (by ~20% and ~10% at z > 1.2 and z < 1.2, respectively). We measure a significant evolution of the mass-size relation of ETGs, with a fractional increment that is almost independent of the stellar mass. ETGs formed at z > 1 appear to be preferentially small, and the evolution of the mass-size relation at z < 1 is driven by both the continuous size growth of the compact galaxies and the appearance of new ETGs with large sizes. We also find that the number density of all passive ETGs increases rapidly, by a factor of five, from z ~ 2 to z ~ 1, and then more mildly by another factor of 1.5 from z ~ 1 to z ~ 0. We interpret these results as evidence that the bulk of the ETGs are formed at 1 < z < 3 through a mechanism that leaves very compact remnants. At z < 1 the compact ETGs grow gradually in size, becoming normal-size galaxies, and at the same time new ETGs with normal-large sizes are formed. Based on data obtained with the Hubble Space Telescope operated by AURA, Inc. for NASA under contract NAS5-26555.

  5. The environmental history of group and cluster galaxies in a Λ cold dark matter universe

    NASA Astrophysics Data System (ADS)

    De Lucia, Gabriella; Weinmann, Simone; Poggianti, Bianca M.; Aragón-Salamanca, Alfonso; Zaritsky, Dennis

    2012-06-01

    We use publicly available galaxy merger trees, obtained applying semi-analytic techniques to a large high-resolution cosmological simulation, to study the environmental history of group and cluster galaxies. Our results highlight the existence of an intrinsic history bias which makes the nature versus nurture (as well as the mass versus environment) debate inherently ill posed. In particular, we show that (i) surviving massive satellites were accreted later than their less massive counterparts, from more massive haloes and (ii) the mixing of galaxy populations is incomplete during halo assembly, which creates a correlation between the time a galaxy becomes satellite and its present distance from the parent halo centre. The weakest trends are found for the most massive satellites, as a result of efficient dynamical friction and late formation times of massive haloes. A large fraction of the most massive group/cluster members are accreted on to the main progenitor of the final halo as central galaxies, while about half of the galaxies with low and intermediate stellar masses are accreted as satellites. Large fractions of group and cluster galaxies (in particular those of low stellar mass) have therefore been ‘pre-processed’ as satellites of groups with mass ˜1013 M⊙. To quantify the relevance of hierarchical structure growth on the observed environmental trends, we have considered observational estimates of the passive galaxy fractions and their variation as a function of halo mass and clustercentric distance. Comparisons with our theoretical predictions require relatively long times (˜5-7 Gyr) for the suppression of star formation in group and cluster satellites. It is unclear how such a gentle mode of strangulation can be achieved by simply relaxing the assumption of instantaneous stripping of the hot gas reservoir associated with accreting galaxies, or if the difficulties encountered by recent galaxy formation models in reproducing the observed trends

  6. Comparative internal kinematics of the H II regions in interacting and isolated galaxies: implications for massive star formation modes

    NASA Astrophysics Data System (ADS)

    Zaragoza-Cardiel, Javier; Beckman, John E.; Font, Joan; García-Lorenzo, Begoña; Camps-Fariña, Artemi; Fathi, Kambiz; James, Philip A.; Erroz-Ferrer, Santiago; Barrera-Ballesteros, Jorge; Cisternas, Mauricio

    2015-08-01

    We have observed 12 interacting galaxy pairs using the Fabry-Perot interferometer GH αFaS (Galaxy H α Fabry-Perot system) on the 4.2-m William Herschel Telescope at the Observatorio del Roque de los Muchachos, La Palma. We present here the Hα surface brightness, velocity and velocity dispersion maps for the 10 systems we have not previously observed using this technique, as well as the physical properties (sizes, Hα luminosities and velocity dispersion) of 1259 H II regions from the full sample. We also derive the physical properties of 1054 H II regions in a sample of 28 isolated galaxies observed with the same instrument in order to compare the two populations of H II regions. We find a population of the brightest H II regions for which the scaling relations, for example the relation between the Hα luminosity and the radius, are clearly distinct from the relations for the regions of lower luminosity. The regions in this bright population are more frequent in the interacting galaxies. We find that the turbulence, and also the star formation rate (SFR), are enhanced in the H II regions in the interacting galaxies. We have also extracted the Hα equivalent widths for the H II regions of both samples, and we have found that the distribution of H II region ages coincides for the two samples of galaxies. We suggest that the SFR enhancement is brought about by gas flows induced by the interactions, which give rise to gravitationally bound gas clouds which grow further by accretion from the flowing gas, producing conditions favourable to star formation.

  7. Orbits of massive satellite galaxies - I. A close look at the Large Magellanic Cloud and a new orbital history for M33

    NASA Astrophysics Data System (ADS)

    Patel, Ekta; Besla, Gurtina; Sohn, Sangmo Tony

    2017-02-01

    The Milky Way (MW) and M31 both harbour massive satellite galaxies, the Large Magellanic Cloud (LMC) and M33, which may comprise up to 10 per cent of their host's total mass. Massive satellites can change the orbital barycentre of the host-satellite system by tens of kiloparsec and are cosmologically expected to harbour dwarf satellite galaxies of their own. Assessing the impact of these effects crucially depends on the orbital histories of the LMC and M33. Here, we revisit the dynamics of the MW-LMC system and present the first detailed analysis of the M31-M33 system utilizing high-precision proper motions and statistics from the dark-matter-only Illustris cosmological simulation. With the latest Hubble Space Telescope proper motion measurements of M31, we reliably constrain M33's interaction history with its host. In particular, like the LMC, M33 is either on its first passage (tinf < 2 Gyr ago) or if M31 is massive (≥2 × 1012 M⊙), it is on a long-period orbit of about 6 Gyr. Cosmological analogues of the LMC and M33 identified in Illustris support this picture and provide further insight about their host masses. We conclude that, cosmologically, massive satellites such as the LMC and M33 are likely completing their first orbits about their hosts. We also find that the orbital energies of such analogues prefer an MW halo mass ˜1.5 × 1012 M⊙ and an M31 halo mass ≥1.5 × 1012 M⊙. Despite conventional wisdom, we conclude it is highly improbable that M33 made a close (<100 kpc) approach to M31 recently (tperi < 3 Gyr ago). Such orbits are rare (<1 per cent) within the 4σ error space allowed by observations. This conclusion cannot be explained by perturbative effects through four-body encounters amongst the MW, M31, M33, and the LMC. This surprising result implies that we must search for a new explanation for M33's strongly warped gas and stellar discs.

  8. Connecting massive galaxies to dark matter haloes in BOSS - I. Is galaxy colour a stochastic process in high-mass haloes?

    NASA Astrophysics Data System (ADS)

    Saito, Shun; Leauthaud, Alexie; Hearin, Andrew P.; Bundy, Kevin; Zentner, Andrew R.; Behroozi, Peter S.; Reid, Beth A.; Sinha, Manodeep; Coupon, Jean; Tinker, Jeremy L.; White, Martin; Schneider, Donald P.

    2016-08-01

    We use subhalo abundance matching (SHAM) to model the stellar mass function (SMF) and clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) `CMASS' sample at z ˜ 0.5. We introduce a novel method which accounts for the stellar mass incompleteness of CMASS as a function of redshift, and produce CMASS mock catalogues which include selection effects, reproduce the overall SMF, the projected two-point correlation function wp, the CMASS dn/dz, and are made publicly available. We study the effects of assembly bias above collapse mass in the context of `age matching' and show that these effects are markedly different compar