WorldWideScience

Sample records for redshift host galaxies

  1. The nuclear to host galaxy relation of high redshift quasars

    CERN Document Server

    Kotilainen, J K; Labita, M; Treves, A; Uslenghi, M

    2007-01-01

    We present near-infrared imaging with ESO VLT+ISAAC of the host galaxies of low luminosity quasars in the redshift range 1 < z < 2, aimed at investigating the relationship between the nuclear and host galaxy luminosities at high redshift. This work complements our previous study to trace the cosmological evolution of the host galaxies of high luminosity quasars (Falomo et al. 2004). The new sample includes 15 low luminosity quasars, nine radio-loud (RLQ) and six radio-quiet (RQQ). They have similar distribution of redshift and optical luminosity, and together with the high luminosity quasars they cover a large range (~4 mag) of the quasar luminosity function. The host galaxies of both types of quasars are in the range of massive inactive ellipticals between L* and 10 L*. RLQ hosts are systematically more luminous than RQQ hosts by a factor of ~2. This difference is similar to that found for the high luminosity quasars. This luminosity gap appears to be independent of the rest-frame U-band luminosity but...

  2. High-redshift quasar host galaxies with adaptive optics

    CERN Document Server

    Kuhlbrodt, B; Wisotzki, L; Jahnke, K

    2005-01-01

    We present K band adaptive optics observations of three high-redshift (z ~ 2.2) high-luminosity quasars, all of which were studied for the first time. We also bserved several point spread function (PSF) calibrators, non-simultaneously because of the small field of view. The significant temporal PSF variations on timescales of minutes inhibited a straightforward scaled PSF removal from the quasar images. Characterising the degree of PSF concentration by the radii encircling 20% and 80% of the total flux, respectively, we found that even under very different observing conditions the r20 vs. r80 relation varied coherently between individual short exposure images, delineating a well-defined relation for point sources. Placing the quasar images on this relation, we see indications that all three objects were resolved. We designed a procedure to estimate the significance of this result, and to estimate host galaxy parameters, by reproducing the statistical distribution of the individual short exposure images. We fi...

  3. Dust in High Redshift Gamma Ray Burst Host Galaxies

    Science.gov (United States)

    Liang, Shunlin; Li, A.

    2009-12-01

    The discovery of high-redshift GRBs opens a new window into the nature of dust in the early universe. We explore the dust properties of the host galaxies of a large sample (32 objects) of long-GRBs at 2.0≤ z ≤ 6.7, with a mean redshift of z=3.34 (corresponding to a look-back time of 1.94 Gyr), by fitting their optical-near-IR afterglow spectra. The average dust extinction in the visual band is AV=0.3. The EB-V/NHI and AV/NHI ratios decrease linearly with the dust-to-gas ratio, suggesting that the dust properties remain unchanged at the epoch of 2.0≤ z ≤ 6.7. The inferred extinction curves are closely reproduced in terms of a mixture of amorphous silicate and graphite. The quanities of amorphous silicate and graphite (relative to H) both appear to decrease with, while their cut-off grain sizes show no significant evolution in the interval 2.0≤ z ≤ 6.7.

  4. An Efficient Approach to Obtaining Large Numbers of Distant Supernova Host Galaxy Redshifts

    CERN Document Server

    Lidman, C; Sullivan, M; Myzska, J; Dobbie, P; Glazebrook, K; Mould, J; Astier, P; Balland, C; Betoule, M; Carlberg, R; Conley, A; Fouchez, D; Guy, J; Hardin, D; Hook, I; Howell, D A; Pain, R; Palanque-Delabrouille, N; Perrett, K; Pritchet, C; Regnault, N; Rich, J

    2012-01-01

    We use the wide-field capabilities of the 2dF fibre positioner and the AAOmega spectrograph on the Anglo-Australian Telescope (AAT) to obtain redshifts of galaxies that hosted supernovae during the first three years of the Supernova Legacy Survey (SNLS). With exposure times ranging from 10 to 60 ksec per galaxy, we were able to obtain redshifts for 400 host galaxies in two SNLS fields, thereby substantially increasing the total number of SNLS supernovae with host galaxy redshifts. The median redshift of the galaxies in our sample that hosted photometrically classified Type Ia supernovae (SNe Ia) is 0.77, which is 25% higher than the median redshift of spectroscopically confirmed SNe Ia in the three-year sample of the SNLS. Our results demonstrate that one can use wide-field fibre-fed multi-object spectrographs on 4m telescopes to efficiently obtain redshifts for large numbers of supernova host galaxies over the large areas of sky that will be covered by future high-redshift supernova surveys, such as the Dark...

  5. Near-infrared imaging of the host galaxies of intermediate redshift steep spectrum radio quasars

    CERN Document Server

    Kotilainen, J K

    2000-01-01

    We present the results of near-infrared H-band (1.65 microns) imaging of 19 steep spectrum radio quasars (SSRQ) in the redshift range 0.5 < z < 1.0. This sample of SSRQs is matched with our previously studied complete sample of 20 flat spectrum radio quasars (FSRQ) with respect to redshift and optical and radio luminosity. We are able to clearly detect the host galaxy in 10 (53 %) SSRQs and marginally in 6 (32 %) others, while the host remains unresolved in 3 (16 %) SSRQs. The galaxies hosting the SSRQs are large (average bulge scale-length R(e) = 9.0+-1.7 kpc) and luminous (average M(H) = -27.2+-1.1). They are, therefore, about 2 mag more luminous than the typical galaxy luminosity L* (M*(H) = -25.0+-0.2), and about 1 mag more luminous than the brightest cluster galaxies (M(H) = -26.3+-0.3). The SSRQ hosts appear to have similar luminosity to those of the FSRQ hosts (M(H) = -27), and they fall between the luminosities of lower redshift (M(H) = -26) and higher redshift (M(H) = -29) radio-loud quasars. T...

  6. AGN host galaxies at redshift z~0.7: peculiar or not?

    CERN Document Server

    Boehm, Asmus; Bell, Eric F; Jahnke, Knud; Wolf, Christian; Bacon, David; Barden, Marco; Gray, Meghan E; Hoeppe, Goetz; Jogee, Sharda; McIntosh, Dan H; Peng, Chien Y; Robaina, Adai R; Balogh, Michael; Barazza, Fabio D; Caldwell, John A R; Heymans, Catherine; Haeussler, Boris; van Kampen, Eelco; Lane, Kyle; Meisenheimer, Klaus; Sanchez, Sebastian F; Taylor, Andy N; Zheng, Xianzhong

    2012-01-01

    We perform a quantitative morphological comparison between the hosts of Active Galactic Nuclei (AGN) and quiescent galaxies at intermediate redshifts (z~0.7). The imaging data are taken from the large HST/ACS mosaics of the GEMS and STAGES surveys. Our main aim is to test whether nuclear activity at this cosmic epoch is triggered by major mergers. Using images of quiescent galaxies and stars, we create synthetic AGN images to investigate the impact of an optical nucleus on the morphological analysis of AGN hosts. Galaxy morphologies are parameterized using the asymmetry index A, concentration index C, Gini coefficient G and M20 index. A sample of ~200 synthetic AGN is matched to 21 real AGN in terms of redshift, host brightness and host-to-nucleus ratio to ensure a reliable comparison between active and quiescent galaxies. The optical nuclei strongly affect the morphological parameters of the underlying host galaxy. Taking these effects into account, we find that the morphologies of the AGN hosts are clearly ...

  7. Low redshift quasars in the SDSS Stripe 82. Host galaxy colors and close environment

    CERN Document Server

    Bettoni, D; Kotilainen, J K; Karhunen, K; Uslenghi, M

    2015-01-01

    We present a photometrical and morphological multicolor study of the properties of low redshift (z<0.3) quasar hosts based on a large and homogeneous dataset of quasars derived from the Sloan Digital Sky Survey (DR7). We used quasars that were imaged in the SDSS Stripe82 that is up to 2 mag deeper than standard Sloan images. This sample is part of a larger dataset of ~400 quasars at z<0.5 for which both the host galaxies and their galaxy environments were studied (Falomo et al. 2014,Karhunen et al. 2014). For 52 quasars we undertake a study of the color of the host galaxies and of their close environments in u,g,r,i and z bands. We are able to resolve almost all the quasars in the sample in the filters g,r,i and z and also in $u$ for about 50% of the targets. We found that the mean colors of the QSO host galaxy (g-i=0.82+-0.26; r-i=0.26+-0.16 and u-g=1.32+-0.25) are very similar to the values of a sample of inactive galaxies matched in terms of redshift and galaxy luminosity with the quasar sample. Ther...

  8. The metallicity and dust content of a redshift 5 gamma-ray burst host galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Sparre, M.; Krühler, T.; Fynbo, J. P. U.; Watson, D. J.; De Ugarte Postigo, A.; Hjorth, J.; Malesani, D. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen (Denmark); Hartoog, O. E.; Kaper, L. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); D' Elia, V. [INAF/Rome Astronomical Observatory, via Frascati 33, I-00040 Monteporzio Catone (Roma) (Italy); Zafar, T. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Afonso, P. M. J. [Physics and Astronomy Department, American River College, 4700 College Oak Drive, Sacramento, CA 95841 (United States); Covino, S. [INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Flores, H. [Laboratoire GEPI, Observatoire de Paris, CNRS-UMR8111, Universite Paris Diderot 5 place Jules Janssen, F-92195 Meudon (France); Goldoni, P. [APC, Astroparticule et Cosmologie, Universite Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10, Rue Alice Domon et Léonie Duquet, F-75205 Paris, Cedex 13 (France); Greiner, J. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, D-85748 Garching (Germany); Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, IS-107 Reykjavik (Iceland); Klose, S. [Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg (Germany); Levan, A. J., E-mail: sparre@dark-cosmology.dk [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); and others

    2014-04-20

    Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A, from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio (DTM), and extinction of the GRB host galaxy at z = 5.0. The host absorption system is a damped Lyα absorber with a very large neutral hydrogen column density of log N(H I)/cm{sup −2}=22.30±0.06 and a metallicity of [S/H] = –1.70 ± 0.10. It is the highest-redshift GRB with such a precise metallicity measurement. The presence of fine-structure lines confirms the z = 5.0 system as the GRB host galaxy and makes this the highest redshift where Fe II fine-structure lines have been detected. The afterglow is mildly reddened with A{sub V} = 0.11 ± 0.04 mag, and the host galaxy has a DTM that is consistent with being equal to or lower than typical values in the Local Group.

  9. Spectroscopic confirmation of a redshift 1.55 supernova host galaxy from the Subaru Deep Field Supernova Survey

    CERN Document Server

    Frederiksen, Teddy F; Hjorth, Jens; Maoz, Dan; Poznanski, Dovi

    2012-01-01

    The Subaru Deep Field (SDF) Supernova Survey discovered 10 Type Ia supernovae (SNe Ia) in the redshift range $1.5redshifts of the host galaxies. However, photometric redshifts might be biased, and the SN sample could be contaminated by active galactic nuclei (AGNs). Unfortunately, measuring spectroscopic redshifts of galaxies in the "redshift desert" 1.5 < z < 2.0 is hard because any prominent emission lines get shifted out of the optical and into the near infrared. Here we report the first robust redshift measurement and classification of hSDF0705.25, an SDF SN Ia host galaxy. Using the X-shooter spectrograph on the Very Large Telescope, we measure a spectroscopic redshift of 1.5456 +/- 0.0003, consistent with its photometric redshift of 1.552 +/- 0.018. From the strong emission-line spectrum we are able to rule out AGN activity and show that the SN host galaxy is a low-metallicity, star-burst dwarf galaxy, similar to typical SN Ia hosts at lower red...

  10. The Host Galaxy and Redshift of the Repeating Fast Radio Burst FRB 121102

    Science.gov (United States)

    Tendulkar, S. P.; Bassa, C. G.; Cordes, J. M.; Bower, G. C.; Law, C. J.; Chatterjee, S.; Adams, E. A. K.; Bogdanov, S.; Burke-Spolaor, S.; Butler, B. J.; Demorest, P.; Hessels, J. W. T.; Kaspi, V. M.; Lazio, T. J. W.; Maddox, N.; Marcote, B.; McLaughlin, M. A.; Paragi, Z.; Ransom, S. M.; Scholz, P.; Seymour, A.; Spitler, L. G.; van Langevelde, H. J.; Wharton, R. S.

    2017-01-01

    The precise localization of the repeating fast radio burst (FRB 121102) has provided the first unambiguous association (chance coincidence probability p ≲ 3 × 10‑4) of an FRB with an optical and persistent radio counterpart. We report on optical imaging and spectroscopy of the counterpart and find that it is an extended (0.″6–0.″8) object displaying prominent Balmer and [O iii] emission lines. Based on the spectrum and emission line ratios, we classify the counterpart as a low-metallicity, star-forming, mr‧ = 25.1 AB mag dwarf galaxy at a redshift of z = 0.19273(8), corresponding to a luminosity distance of 972 Mpc. From the angular size, the redshift, and luminosity, we estimate the host galaxy to have a diameter ≲4 kpc and a stellar mass of M* ∼ (4–7) × 107 M⊙, assuming a mass-to-light ratio between 2 to 3 M⊙ L⊙‑1. Based on the Hα flux, we estimate the star formation rate of the host to be 0.4 M⊙ yr‑1 and a substantial host dispersion measure (DM) depth ≲324 pc cm‑3. The net DM contribution of the host galaxy to FRB 121102 is likely to be lower than this value depending on geometrical factors. We show that the persistent radio source at FRB 121102’s location reported by Marcote et al. is offset from the galaxy’s center of light by ∼200 mas and the host galaxy does not show optical signatures for AGN activity. If FRB 121102 is typical of the wider FRB population and if future interferometric localizations preferentially find them in dwarf galaxies with low metallicities and prominent emission lines, they would share such a preference with long gamma-ray bursts and superluminous supernovae.

  11. Host-galaxy Properties of 32 Low-redshift Superluminous Supernovae from the Palomar Transient Factory

    Science.gov (United States)

    Perley, D. A.; Quimby, R. M.; Yan, L.; Vreeswijk, P. M.; De Cia, A.; Lunnan, R.; Gal-Yam, A.; Yaron, O.; Filippenko, A. V.; Graham, M. L.; Laher, R.; Nugent, P. E.

    2016-10-01

    We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013 and derive measurements of their luminosities, star formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe (SLSNe I) are found almost exclusively in low-mass ({M}* \\lt 2× {10}9 {M}ȯ ) and metal-poor (12 + log10[O/H] \\lt 8.4) galaxies. We compare the mass and metallicity distributions of our sample to nearby galaxy catalogs in detail and conclude that the rate of SLSNe I as a fraction of all SNe is heavily suppressed in galaxies with metallicities ≳ 0.5 {Z}ȯ . Extremely low metallicities are not required and indeed provide no further increase in the relative SLSN rate. Several SLSN I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star formation histories. Type II (hydrogen-rich) SLSNe (SLSNe II) are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is an SLSN I in a massive, luminous infrared galaxy at redshift z = 0.29, while PTF 10tpz is an SLSN II located in the nucleus of an early-type host at z = 0.04.

  12. LONG GRBs ARE METALLICITY-BIASED TRACERS OF STAR FORMATION: EVIDENCE FROM HOST GALAXIES AND REDSHIFT DISTRIBUTION

    Energy Technology Data Exchange (ETDEWEB)

    Wang, F. Y.; Dai, Z. G., E-mail: fayinwang@nju.edu.cn, E-mail: dzg@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2014-07-01

    We investigate the mass distribution of long gamma-ray burst (GRB) host galaxies and the redshift distribution of long GRBs by considering that long GRBs occur in low-metallicity environments. We calculate the upper limit on the stellar mass of a galaxy which can produce long GRBs by utilizing the mass-metallicity (M-Z) relation of galaxies. After comparing with the observed GRB host galaxies masses, we find that the observed GRB host galaxy masses can fit the predicted masses well if GRBs occur in low-metallicity 12 + log (O/H){sub KK04} < 8.7. GRB host galaxies have low metallicity, low mass, and high star formation rate compared with galaxies of seventh data release of the Sloan Digital Sky Survey. We also study the cumulative redshift distribution of the latest Swift long GRBs by adding dark GRBs and 10 new GRBs redshifts from the TOUGH survey. The observed discrepancy between the GRB rate and the star formation history can be reconciled by considering that GRBs tend to occur in low-metallicity galaxies with 12 + log (O/H){sub KK04} < 8.7. We conclude that the metallicity cutoff that can produce long GRBs is about 12 + log (O/H){sub KK04} < 8.7 from the host mass distribution and redshift distribution.

  13. The metallicity and dust content of a redshift 5 gamma-ray burst host galaxy

    DEFF Research Database (Denmark)

    Sparre, M.; Hartoog, O. E.; Krühler, T.

    2014-01-01

    Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio and extinction of the GRB host...... galaxy at z=5.0. The host absorption system is a damped Lyman-alpha absorber (DLA) with a very large neutral hydrogen column density of log N(HI)/cm^(-2) = 22.30 +/- 0.06, and a metallicity of [S/H]= -1.70 +/- 0.10. It is the highest redshift GRB with such a precise metallicity measurement. The presence...

  14. Long Gamma-Ray Bursts and Their Host Galaxies at High Redshift

    CERN Document Server

    Lapi, A; Bosnjak, Z; Celotti, A; Bressan, A; Granato, G L; Danese, L

    2008-01-01

    Motivated by the recent observational and theoretical evidence that long Gamma-Ray Bursts (GRBs) are likely associated with low metallicity, rapidly rotating massive stars, we examine the cosmological star formation rate (SFR) below a critical metallicity Z_crit~Z_sun/10 - Z_sun/5, to estimate the event rate of high-redshift long GRB progenitors. To this purpose, we exploit a galaxy formation scenario already successfully tested on a wealth of observational data on (proto)spheroids, Lyman break galaxies, Lyman alpha emitters, submm galaxies, quasars, and local early-type galaxies. We find that the predicted rate of long GRBs amounts to about 300 events/yr/sr, of which about 30 per cent occur at z>~6. Correspondingly, the GRB number counts well agree with the bright SWIFT data, without the need for an intrinsic luminosity evolution. Moreover, the above framework enables us to predict properties of the GRB host galaxies. Most GRBs are associated with low mass galaxy halos M_H~10^12 M_sun have larger extinction ...

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

    CERN Document Server

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

    2016-01-01

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

  16. Physical conditions and element abundances in SN and GRB host galaxies at different redshifts

    CERN Document Server

    Contini, M

    2016-01-01

    We compare the physical parameters and the relative abundances calculated throughout supernova (SN) and gamma-ray burst (GRB) host galaxies by the detailed modelling of the spectra. The results show that : 1) shock velocities are lower in long period GRB (LGRB) than in SN host galaxies. 2) O/H relative abundance in SN hosts are scattered within a range 8.0 10^5 K. Ts in LGRB hosts are 3-8 10^4 K. 4) Ha increases with the ionization parameter U. We suggest that SN-host symbiosis is stronger in terms of host galaxy activity than GRB-host in the range of energies related to the near UV - optical - near IR spectra.

  17. A revised host galaxy association for GRB 020819B: a high-redshift dusty starburst, not a low-redshift gas-poor spiral

    Science.gov (United States)

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

    2017-02-01

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

  18. Host-Galaxy Properties of 32 Low-Redshift Superluminous Supernovae from the Palomar Transient Factory

    CERN Document Server

    Perley, Daniel A; Yan, Lin; Vreeswijk, Paul; De Cia, Annalisa; Lunnan, Ragnhild; Gal-Yam, Avishay; Yaron, Ofer; Filippenko, Alexei V; Graham, Melissa L; Nugent, Peter E

    2016-01-01

    We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013, and derive measurements of their luminosities, star-formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe are found almost exclusively in low-mass (M 0.5 Z_sun. Extremely low metallicities are not required, and indeed provide no further increase in the relative SLSN rate. Several SLSN-I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star-formation histories. Type-II (hydrogen-rich) SLSNe are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is a Type I SLSN in a massive, luminous infrared galaxy at re...

  19. A Monster At Any Other Epoch: Are Intermediate Redshift ULIRGs the Progenitors of QSO Host Galaxies?

    Science.gov (United States)

    Rothberg, Barry; Fischer, Jackie; Rodrigues, Myriam; Pirzkal, Nor

    2015-08-01

    There is a clear progression from merger-induced SF to QSO activity via Ultraluminous Infrared Galaxies (ULIRGs). While not all mergers are ULIRGs, multi-wavelength imaging confirms that all local ULIRGs are mergers. At 0.4 1 are responsible for ˜ 70% of the co-moving IR density. At these earlier epochs ULIRGs contained more gas, formed stars faster, and their number density was much higher. At z>1 there are conflicting conclusions about ULIRGs. Many studies conclude they are massive star-forming galaxies, not major mergers nor AGN. Nearly all studies of ULIRGs at z > 0.4 have selected these systems via scaling observed 24μm or 170μm Spitzer fluxes to integrated 8-1000μm fluxes and inferring masses from scaling photometric fluxes or millimeter observations of CO gas emission. These methods often rely heavily on uncertain assumptions (e.g. gas conversions, SED fitting and templates). Instead, we have assembled a representative sample of "classically" selected ULIRGs (60 and 100μm IRAS fluxes and 12 and 25μm WISE fluxes) for 0.4 < z < 1.0 and obtained optical and near-IR imaging and spectroscopy from Hubble Space Telescope, Keck, and the Large Binocular Telescope. We use the same techniques for measuring the dynamical and BH masses of ULIRGs in the local Universe to measure these parameters in more distant systems. Unlike other methods, we directly measure the mass at an epoch when galaxy formation and evolution appears to have changed dramatically from what we see today and compare these intermediate redshift ULIRGs with their counterparts in the local Universe. Our restframe optical and UV spectroscopy also allow us to directly probe gas-metallicities, outflows, and measure the properties of their stellar populations. Our results indicate that these intermediate redshift ULIRGs are dynamically similar to their local counterparts.

  20. Very high redshift radio galaxies

    Energy Technology Data Exchange (ETDEWEB)

    van Breugel, W.J.M., LLNL

    1997-12-01

    High redshift radio galaxies (HzRGs) provide unique targets for the study of the formation and evolution of massive galaxies and galaxy clusters at very high redshifts. We discuss how efficient HzRG samples ae selected, the evidence for strong morphological evolution at near-infracd wavelengths, and for jet-induced star formation in the z = 3 800 HzRG 4C41 17

  1. High-redshift quasars host galaxies: is there a stellar mass crisis?

    CERN Document Server

    Valiante, Rosa; Salvadori, Stefania; Gallerani, Simona

    2014-01-01

    We investigate the evolutionary properties of a sample of quasars at 5hosts have final stellar masses in the range $(4-6)\\times 10^{11} M_{sun}$, a factor 3-30 larger than the upper limits allowed by the observations. We discuss alternative scenarios to alleviate this apparent tension: the most likely explanation resides in the large uncertainties that still affect dynamical mass measurements in these high-z galaxies. In addition, during the transition between the starburs...

  2. The Highest Redshift Radio Galaxies

    CERN Document Server

    Van Breugel, W

    2000-01-01

    At low redshifts powerful radio sources are uniquely associated with massive galaxies, and are thought to be powered by supermassive black holes. Modern 8m -- 10m telescopes may be used used to find their likely progenitors at very high redshifts to study their formation and evolution.

  3. The redshifted selected sample of long gamma-ray burst host galaxies: the complete metallicity measurements at $z \\leq 0.41$

    CERN Document Server

    Niino, Yuu; Hashimoto, Tetsuya; Hattori, Takashi; Ishikawa, Shoto; Kashikawa, Nobunari; Kosugi, George; Onoue, Masafusa; Toshikawa, Jun; Yabe, Kiyoto

    2016-01-01

    We present the complete list of host galaxy metallicities for all long GRBs whose redshifts were determined to be $\\leq 0.41$ before the end of March 2014, including newly obtained spectroscopic datasets of the host galaxies of GRB 060614, 090417B, and 130427A. We compare the metallicity distribution of the redshift selected complete sample to the model predictions, and constrain the relation between metallicity and GRB occurrence. We take account of spatial variation of metallicities among star forming regions within a galaxy. We found that the models, in which only low-metallicity stars produce GRBs with a sharp cutoff of GRB production efficiency around 12+log(O/H) $\\sim$ 8.2, can well reproduce the observed distribution, while the models with moderate (or no) metallicity dependence are not consitistent with the observations. This is the first fair estimate of the metallicity distribution of GRB host galaxies based on the redshift selected complete sample in the {\\it Swift} era. We also discuss possible sa...

  4. The Metallicity and Dust Content of a Redshift 5 Gamma-Ray Burst Host Galaxy

    NARCIS (Netherlands)

    Sparre, M.; Hartoog, O.E.; Krühler, T.; Fynbo, J.P.U.; Watson, D.J.; Wiersema, K.; D'Elia, V.; Zafar, T.; Afonso, P.M.J.; Covino, S.; de Ugarte Postigo, A.; Flores, H.; Goldoni, P.; Greiner, J.; Hjorth, J.; Jakobsson, P.; Kaper, L.; Klose, S.; Levan, A.J.; Malesani, D.; Milvang-Jensen, B.; Nardini, M.; Piranomonte, S.; Sollerman, J.; Sánchez-Ramírez, R.; Schulze, S.; Tanvir, N.R.; Vergani, S.D.; Wijers, R.A.M.J.

    2014-01-01

    Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A, from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio (DTM), and extinction of the GR

  5. High Resolution Simulations for Hierarchical Formation of Dark Matter Halos Hosting Galaxies and AGNs at High Redshift

    Science.gov (United States)

    Ishiyama, Tomoaki

    2015-08-01

    We present the evolution of dark matter halos in six large cosmological N-body simulations, called the ν2GC (New Numerical Galaxy Catalog) simulations on the basis of the LCDM cosmology consistent with observational results obtained by the Planck satellite. The largest simulation consists of 81923 (550 billion) dark matter particles in a box of 1.12h-1Gpc (a mass resolution of 2.20×108 h-1M⊙). Among simulations utilizing boxes larger than 1h-1Gpc, our simulation yields the highest resolution simulation that has ever been achieved. Compared with the Millennium simulation (Springel et al. 2005), our simulation offers the advantages of a mass resolution that is four times better and a spatial volume that is 11 times larger. A ν2GC simulation with the smallest box consists of eight billions particles in a box of 70h-1Mpc (a mass resolution of 3.44×106 -1M⊙). These simulations can follow the evolution of halos over masses of eight orders of magnitude, from small dwarf galaxies to massive clusters. Using the unprecedentedly high resolution and powerful statistics of the ν2GC simulations, we provide statistical results of the halo mass function, mass accretion rate, formation redshift, and merger statistics, and present accurate fitting functions for the Planck cosmology, from redshift 10 to 0. By combining the ν2GC simulations with our new semi-analytic galaxy formation model, we are able to prepare mock catalogs of galaxies and active galactic nuclei, which will be made publicly available in the near future.

  6. Old Galaxies at High Redshift

    CERN Document Server

    Dunlop, J

    1997-01-01

    The most passive galaxies at high redshift are unlikely to be identified by either narrow-band emission-line searches, or by Lyman limit searches (both techniques which have been highlighted at this meeting) simply because such selection methods rely on the presence of a strong ultraviolet component. Selection on the basis of extreme radio power has also proved to yield optically active objects with the majority of high-redshift objects studied to date displaying complex elongated optical/UV morphologies, relatively blue optical-ultraviolet continuum colours, and strong emission lines. These features, coupled with the failure to detect any spectral signatures of old stars at $z > 1$, has led to the suggestion that these galaxies are being observed close to or even during a general epoch of formation. However, we have recently demonstrated that radio selection at significantly fainter (mJy) flux densities can be used to identify apparently passively evolving elliptical galaxies at high redshift. Deep Keck spec...

  7. Bayesian redshift-space distortions correction from galaxy redshift surveys

    CERN Document Server

    Kitaura, Francisco-Shu; Angulo, Raul E; Chuang, Chia-Hsun; Rodriguez-Torres, Sergio; Monteagudo, Carlos Hernandez; Prada, Francisco; Yepes, Gustavo

    2015-01-01

    We present a Bayesian reconstruction method which maps a galaxy distribution from redshift-space to real-space inferring the distances of the individual galaxies. The method is based on sampling density fields assuming a lognormal prior with a likelihood given by the negative binomial distribution function modelling stochastic bias. We assume a deterministic bias given by a power law relating the dark matter density field to the expected halo or galaxy field. Coherent redshift-space distortions are corrected in a Gibbs-sampling procedure by moving the galaxies from redshift-space to real-space according to the peculiar motions derived from the recovered density field using linear theory with the option to include tidal field corrections from second order Lagrangian perturbation theory. The virialised distortions are corrected by sampling candidate real-space positions (being in the neighbourhood of the observations along the line of sight), which are compatible with the bulk flow corrected redshift-space posi...

  8. Measuring Galaxy Environments with Deep Redshift Surveys

    CERN Document Server

    Cooper, M C; Madgwick, D S; Gerke, B F; Yan, R; Davis, M; Cooper, Michael C.; Newman, Jeffrey A.; Madgwick, Darren S.; Gerke, Brian F.; Yan, Renbin; Davis, Marc

    2005-01-01

    We study the applicability of several galaxy environment measures (n^th-nearest-neighbor distance, counts in an aperture, and Voronoi volume) within deep redshift surveys. Mock galaxy catalogs are employed to mimic representative photometric and spectroscopic surveys at high redshift (z ~ 1). We investigate the effects of survey edges, redshift precision, redshift-space distortions, and target selection upon each environment measure. We find that even optimistic photometric redshift errors (\\sigma_z = 0.02) smear out the line-of-sight galaxy distribution irretrievably on small scales; this significantly limits the application of photometric redshift surveys to environment studies. Edges and holes in a survey field dramatically affect the estimation of environment, with the impact of edge effects depending upon the adopted environment measure. These edge effects considerably limit the usefulness of smaller survey fields (e.g. the GOODS fields) for studies of galaxy environment. In even the poorest groups and c...

  9. Lensing convergence in galaxy redshift surveys

    CERN Document Server

    Cardona, Wilmar; Kunz, Martin; Montanari, Francesco

    2016-01-01

    In this letter we demonstrate the importance of including the lensing contribution in galaxy clustering analyses with large galaxy redshift surveys. It is well known that radial cross-correlations between different redshift bins of galaxy surveys are dominated by lensing. But we show here that also neglecting lensing in the auto-correlations within one bin severely biases cosmological parameter estimation with redshift surveys. It leads to significant shifts for several cosmological parameters, most notably the scalar amplitude, the scalar spectral index and in particular the neutrino mass scale. Especially the latter parameter is one of the main targets of future galaxy surveys.

  10. The high redshift galaxy population in hierarchical galaxy formation models

    CERN Document Server

    Kitzbichler, M G; Kitzbichler, Manfred G.; White, Simon D. M.

    2006-01-01

    We compare observations of the high redshift galaxy population to the predictions of the galaxy formation model of Croton et al. (2006). This model, implemented on the Millennium Simulation of the concordance LCDM cosmogony, introduces "radio mode" feedback from the central galaxies of groups and clusters in order to obtain quantitative agreement with the luminosity, colour, morphology and clustering properties of the low redshift galaxy population. Here we compare the predictions of this same model to the observed counts and redshift distributions of faint galaxies, as well as to their inferred luminosity and mass functions out to redshift 5. With the exception of the mass functions, all these properties are sensitive to modelling of dust obscuration. A simple but plausible treatment gives moderately good agreement with most of the data, although the predicted abundance of relatively massive (~M*) galaxies appears systematically high at high redshift, suggesting that such galaxies assemble earlier in this mo...

  11. ALMA Observations Show Major Mergers Among the Host Galaxies of Fast-growing, High-redshift Supermassive Black Holes

    CERN Document Server

    Trakhtenbrot, Benny; Netzer, Hagai; Cicone, Claudia; Maiolino, Roberto; Shemmer, Ohad

    2016-01-01

    We present new ALMA band-7 data for a sample of six luminous quasars at z~4.8, powered by fast-growing supermassive black holes (SMBHs) with rather uniform properties: the typical accretion rates and black hole masses are L/L_Edd~0.7 and M_BH~10^9 M_sol. Our sample consists of three "FIR-bright" sources which were individually detected in previous Herschel/SPIRE observations, with star formation rates of SFR>1000 M_sol/yr, and three "FIR-faint" sources for which Herschel stacking analysis implies a typical SFR of ~400 M_sol/yr. The dusty interstellar medium in the hosts of all six quasars is clearly detected in the ALMA data, and resolved on scales of 2 kpc, in both continuum (\\lambda_rest~150um) and [CII]157.74um line emission. The continuum emission is in good agreement with the expectations from the Herschel data, confirming the intense SF activity in the quasars' hosts. Importantly, we detect companion sub-mm galaxies (SMGs) for three sources -- one FIR-bright and two FIR-faint, separated by ~14-45 kpc an...

  12. Calibrating Photometric Redshifts of Luminous Red Galaxies

    CERN Document Server

    Padmanabhan, N; Schlegel, D J; Bridges, T J; Brinkmann, J; Cannon, R; Connolly, A J; Croom, S M; Csabai, I; Drinkwater, M; Eisenstein, D J; Hewett, P C; Loveday, J; Nichol, R C; Pimbblet, K A; De Propris, R; Schneider, D P; Scranton, R; Seljak, U; Shanks, T; Szapudi, I; Szalay, A S; Wake, D; Padmanabhan, Nikhil; Budavari, Tamas; Schlegel, David J.; Bridges, Terry; Brinkmann, Jonathan; Cannon, Russell; Connolly, Andrew J.; Croom, Scott M.; Csabai, Istvan; Drinkwater, Michael; Eisenstein, Daniel J.; Hewett, Paul C.; Loveday, Jon; Nichol, Robert C.; Pimbblet, Kevin A.; Propris, Roberto De; Schneider, Donald P.; Scranton, Ryan; Seljak, Uros; Shanks, Tom; Szapudi, Istvan; Szalay, Alexander S.; Wake, David

    2004-01-01

    We discuss the construction of a photometric redshift catalogue of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS), emphasizing the principal steps necessary for constructing such a catalogue -- (i) photometrically selecting the sample, (ii) measuring photometric redshifts and their error distributions, (iii) and estimating the true redshift distribution. We compare two photometric redshift algorithms for these data and find that they give comparable results. Calibrating against the SDSS and SDSS-2dF spectroscopic surveys, we find that the photometric redshift accuracy is $\\sigma \\sim 0.03$ for redshifts less than 0.55 and worsens at higher redshift ($\\sim 0.06$). These errors are caused by photometric scatter, as well as systematic errors in the templates, filter curves, and photometric zeropoints. We also parametrize the photometric redshift error distribution with a sum of Gaussians, and use this model to deconvolve the errors from the measured photometric redshift distribution to est...

  13. The Compact, ∼1 kpc Host Galaxy of a Quasar at a Redshift of 7.1

    Science.gov (United States)

    Venemans, Bram P.; Walter, Fabian; Decarli, Roberto; Bañados, Eduardo; Hodge, Jacqueline; Hewett, Paul; McMahon, Richard G.; Mortlock, Daniel J.; Simpson, Chris

    2017-03-01

    We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [C ii] fine-structure line and the underlying far-infrared (FIR) dust continuum emission in J1120+0641, the most distant quasar currently known (z=7.1). We also present observations targeting the CO(2–1), CO(7–6), and [C i] 369 μm lines in the same source obtained at the Very Large Array and Plateau de Bure Interferometer. We find a [C ii] line flux of {F}[{{C}{{II}}]}=1.11+/- 0.10 Jy {km} {{{s}}}-1 and a continuum flux density of {S}227{GHz}=0.53+/- 0.04 mJy beam‑1, consistent with previous unresolved measurements. No other source is detected in continuum or [C ii] emission in the field covered by ALMA (∼ 25″). At the resolution of our ALMA observations (0.″23, or 1.2 kpc, a factor of ∼70 smaller beam area compared to previous measurements), we find that the majority of the emission is very compact: a high fraction (∼80%) of the total line and continuum flux is associated with a region 1–1.5 kpc in diameter. The remaining ∼20% of the emission is distributed over a larger area with radius ≲4 kpc. The [C ii] emission does not exhibit ordered motion on kiloparsec scales: applying the virial theorem yields an upper limit on the dynamical mass of the host galaxy of (4.3+/- 0.9)× {10}10 {M}ȯ , only ∼20 × higher than the central black hole (BH). The other targeted lines (CO(2–1), CO(7–6), and [C i]) are not detected, but the limits of the line ratios with respect to the [C ii] emission imply that the heating in the quasar host is dominated by star formation, and not by the accreting BH. The star formation rate (SFR) implied by the FIR continuum is 105–340 {M}ȯ {{yr}}-1, with a resulting SFR surface density of ∼100–350 {M}ȯ {{yr}}-1 kpc‑2, well below the value for Eddington-accretion-limited star formation.

  14. Morphologies at High Redshift from Galaxy Zoo

    Science.gov (United States)

    Masters, Karen; Melvin, Tom; Simmons, Brooke; Willett, Kyle; Lintott, Chris

    2015-08-01

    I will present results from Galaxy Zoo classification of galaxies observed in public observed frame optical HST surveys (e.g. COSMOS, GOODS) as well as in observed frame NIR with (ie. CANDELS). Early science results from these classifications have investigated the changing bar fraction in disc galaxies as a function of redshift (to z~1 in Melvin et al. 2014; and at z>1 in Simmons et al. 2015), as well as how the morphologies of galaxies on the red sequence have been changing since z~1 (Melvin et al. in prep.). These unique dataset of quantitative visual classifications for high redshift galaxies will be made public in forthcoming publications (planned as Willett et al. for Galaxy Zoo Hubble, and Simmons et al. for Galaxy Zoo CANDELS).

  15. Photometric Redshifts of Galaxies in COSMOS

    CERN Document Server

    Mobasher, B; Scoville, N Z; Dahlen, T; Salvato, M; Aussel, H; Thompson, D J; Feldmann, R; Tasca, L; Lefèvre, O; Lilly, S; Carollo, C M; Kartaltepe, J S; McCracken, H; Mould, J; Renzini, A; Sanders, D B; Shopbell, P L; Taniguchi, Y; Ajiki, M; Shioya, Y; Contini, T; Giavalisco, M; Ilbert, O; Iovino, A; Le Brun, V; Mainieri, V; Mignoli, M; Scodeggio, M

    2006-01-01

    We measure photometric redshifts and spectral types for galaxies in the COSMOS survey. We use template fitting technique combined with luminosity function priors and with the option to simultaneously estimate dust extinction (i.e. E(B-V)) for each galaxy.Our estimated redshifts are accurate to i<25 and z~1.2. Using simulations with sampling and noise characteristics similar to those in COSMOS, the accuracy and reliability is estimated for the photometric redshifts as a function of the magnitude limits of the sample, S/N ratios and the number of bands used. From the simulations we find that the ratio of derived 95% confidence interval in the redshift probability distribution to the estimated photometric redshift (D95) can be used to identify and exclude the catastrophic failures in the photometric redshift estimates. We compare the derived redshifts with high-reliability spectroscopic redshifts for a sample of 868 normal galaxies with z < 1.2 from zCOSMOS. Considering different scenarios, depending on us...

  16. Measuring Gravitational Redshifts in Galaxy Clusters

    CERN Document Server

    Kaiser, Nick

    2013-01-01

    Wojtak {\\it et al} have stacked 7,800 clusters from the SDSS survey in redshift space. They find a small net blue-shift for the cluster galaxies relative to the brightest cluster galaxies, which agrees quite well with the gravitational redshift from GR. Zhao {\\it et al.} have pointed out that, in addition to the gravitational redshift, one would expect to see transverse Doppler (TD) redshifts, and that these two effects are generally of the same order. Here we show that there are other corrections that are also of the same order of magnitude. The fact that we observe galaxies on our past light cone results in a bias such that more of the galaxies observed are moving away from us in the frame of the cluster than are moving towards us. This causes the observed average redshift to be $\\langle \\delta z \\rangle = -\\langle \\Phi \\rangle + \\langle \\beta^2 \\rangle / 2 + \\langle \\beta_x^2 \\rangle$, with $\\beta_x$ is the line of sight velocity. That is if we average over galaxies with equal weight. If the galaxies in ea...

  17. The KMOS AGN Survey at High redshift (KASHz): the prevalence and drivers of ionised outflows in the host galaxies of X-ray AGN

    CERN Document Server

    Harrison, C M; Mullaney, J R; Stott, J P; Swinbank, A M; Arumugam, V; Bauer, F E; Bower, R G; Bunker, A J; Sharples, R M

    2015-01-01

    We present the first results from the KMOS AGN Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic survey of z>0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN (Lx=10^42-10^45 erg/s), for which we observed [O III] (z=1.1-1.7) or Halpha emission (z=0.6-1.1). The targets have X-ray luminosities representative of the parent AGN population and we explore the emission-line luminosities as a function of X-ray luminosity. For the [O III] targets, ~50 per cent have ionised gas velocities indicative of gas that is dominated by outflows and/or highly turbulent material (i.e., overall line-widths >~600 km/s). The most luminous half (i.e., Lx>6x10^43 erg/s) have a >~2 times higher incidence of such velocities. On the basis of our results, we find no evidence that X-ray obscured AGN are more likely to host extreme kinematics than unobscured AGN. Our KASHz sample has a distribution of gas velocities that is consistent with a luminosity-matched sample of z<0.4 AGN. This implies little ev...

  18. Measuring our Universe from Galaxy Redshift Surveys

    Directory of Open Access Journals (Sweden)

    Lahav Ofer

    2004-07-01

    Full Text Available Galaxy redshift surveys have achieved significant progress over the last couple of decades. Those surveys tell us in the most straightforward way what our local Universe looks like. While the galaxy distribution traces the bright side of the Universe, detailed quantitative analyses of the data have even revealed the dark side of the Universe dominated by non-baryonic dark matter as well as more mysterious dark energy (or Einstein's cosmological constant. We describe several methodologies of using galaxy redshift surveys as cosmological probes, and then summarize the recent results from the existing surveys. Finally we present our views on the future of redshift surveys in the era of precision cosmology.

  19. Red galaxies at high redshift

    NARCIS (Netherlands)

    Wuyts, Stijn Elisabeth Raphaël

    2007-01-01

    From its origin at the center of a star to the edge, through the surrounding gas and dust in the distant galaxy, through the intergalactic medium, traveling billions of light years only to be reflected by a mirror and captured by a detector; the little amount of light observed from galaxies in the e

  20. The CNOC2 Field Galaxy Redshift Survey

    CERN Document Server

    Carlberg, R G; Morris, S L; Lin, H; Sawicki, M; Wirth, G; Patton, D; Shepherd, C W; Ellingson, E; Schade, D J; Pritchet, C J; Hartwick, F D A

    1998-01-01

    The CNOC2 field galaxy redshift survey is designed to provide measurements of the evolution of galaxies and their clustering over the redshift range 0 to 0.7. The sample is spread over four sky patches with a total area of about 1.5 square degrees. Here we report preliminary results based on two of the sky patches, and the redshift range of 0.15 to 0.55. We find that galaxy evolution can be statistically described as nearly pure luminosity evolution of early and intermediate SED types, and nearly pure density evolution of the late SED types. The correlation of blue galaxies relative to red galaxies is similar on large scales but drops by a factor of three on scales less than about 0.3/h mpc, approximately the mean scale of virialization. There is a clear, but small, 60%, change in clustering with 1.4 mag of luminosity. To minimize these population effects in our measurement of clustering evolution, we choose galaxies with M_r^{k,e}<= -20 mag as a population whose members are most likely to be conserved wit...

  1. Host Galaxy Identification for Supernova Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve; Spinka, Harold; Kessler, Richard; Goldstein, Daniel A.; Liotine, Camille; Pomian, Katarzyna; D’Andrea, Chris B.; Sullivan, Mark; Carretero, Jorge; Castander, Francisco J.; Nichol, Robert C.; Finley, David A.; Fischer, John A.; Foley, Ryan J.; Kim, Alex G.; Papadopoulos, Andreas; Sako, Masao; Scolnic, Daniel M.; Smith, Mathew; Tucker, Brad E.; Uddin, Syed; Wolf, Rachel C.; Yuan, Fang; Abbott, Tim M. C.; Abdalla, Filipe B.; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, David; Rosell, Aurelio Carnero; Kind, Matias Carrasco; Cunha, Carlos E.; Costa, Luiz N. da; Desai, Shantanu; Doel, Peter; Eifler, Tim F.; Evrard, August E.; Flaugher, Brenna; Fosalba, Pablo; Gaztañaga, Enrique; Gruen, Daniel; Gruendl, Robert; James, David J.; Kuehn, Kyler; Kuropatkin, Nikolay; Maia, Marcio A. G.; Marshall, Jennifer L.; Miquel, Ramon; Plazas, Andrés A.; Romer, A. Kathy; Sánchez, Eusebio; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Sobreira, Flávia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Walker, Alistair R.; Wester, William

    2016-11-08

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST), which will discover SNe by the thousands. Spectroscopic resources are limited, so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.

  2. Host Galaxy Identification for Supernova Surveys

    Science.gov (United States)

    Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve; Spinka, Harold; Kessler, Richard; Goldstein, Daniel A.; Liotine, Camille; Pomian, Katarzyna; D'Andrea, Chris B.; Sullivan, Mark; Carretero, Jorge; Castander, Francisco J.; Nichol, Robert C.; Finley, David A.; Fischer, John A.; Foley, Ryan J.; Kim, Alex G.; Papadopoulos, Andreas; Sako, Masao; Scolnic, Daniel M.; Smith, Mathew; Tucker, Brad E.; Uddin, Syed; Wolf, Rachel C.; Yuan, Fang; Abbott, Tim M. C.; Abdalla, Filipe B.; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, David; Carnero Rosell, Aurelio; Carrasco Kind, Matias; Cunha, Carlos E.; da Costa, Luiz N.; Desai, Shantanu; Doel, Peter; Eifler, Tim F.; Evrard, August E.; Flaugher, Brenna; Fosalba, Pablo; Gaztañaga, Enrique; Gruen, Daniel; Gruendl, Robert; James, David J.; Kuehn, Kyler; Kuropatkin, Nikolay; Maia, Marcio A. G.; Marshall, Jennifer L.; Miquel, Ramon; Plazas, Andrés A.; Romer, A. Kathy; Sánchez, Eusebio; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Sobreira, Flávia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Walker, Alistair R.; Wester, William

    2016-12-01

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope, which will discover SNe by the thousands. Spectroscopic resources are limited, and so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate “hostless” SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.

  3. Host Galaxy Identification for Supernova Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Ravi R.; et al.

    2016-04-20

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST), which will discover SNe by the thousands. Spectroscopic resources are limited, so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.

  4. Anomaly detection for machine learning redshifts applied to SDSS galaxies

    CERN Document Server

    Hoyle, Ben; Paech, Kerstin; Bonnett, Christopher; Seitz, Stella; Weller, Jochen

    2015-01-01

    We present an analysis of anomaly detection for machine learning redshift estimation. Anomaly detection allows the removal of poor training examples, which can adversely influence redshift estimates. Anomalous training examples may be photometric galaxies with incorrect spectroscopic redshifts, or galaxies with one or more poorly measured photometric quantity. We select 2.5 million 'clean' SDSS DR12 galaxies with reliable spectroscopic redshifts, and 6730 'anomalous' galaxies with spectroscopic redshift measurements which are flagged as unreliable. We contaminate the clean base galaxy sample with galaxies with unreliable redshifts and attempt to recover the contaminating galaxies using the Elliptical Envelope technique. We then train four machine learning architectures for redshift analysis on both the contaminated sample and on the preprocessed 'anomaly-removed' sample and measure redshift statistics on a clean validation sample generated without any preprocessing. We find an improvement on all measured stat...

  5. Jellyfish galaxies at low redshift

    CERN Document Server

    Poggianti, B M; Omizzolo, A; Gullieuszik, M; Bettoni, D; Moretti, A; Paccagnella, A; Jaffe', Y L; Vulcani, B; Fritz, J; Couch, W; D'Onofrio, M

    2015-01-01

    Jellyfish galaxies are galaxies that exhibit tentacles of debris material suggestive of gas stripping. We have conducted the first systematic search for jellyfish galaxies at low-z (z=0.04-0.07) in different environments. We have visually inspected B and V-band images and identified 241+153 candidates in 41+31 galaxy clusters of the OMEGAWINGS+WINGS sample and 99 candidates in groups and lower mass structures in the PM2GC sample. This large sample is well suited for follow-up studies of the gas and for a detailed analysis of the environments where such episodes of gas stripping occur. We present here the atlas of jellyfish candidates, a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Jellyfish candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion or X-ray luminosity. Interestingly, convincing cases of jellyfish candidates are also found ...

  6. Hierarchical Bayesian inference of galaxy redshift distributions from photometric surveys

    CERN Document Server

    Leistedt, Boris; Peiris, Hiranya V

    2016-01-01

    Accurately characterizing the redshift distributions of galaxies is essential for analysing deep photometric surveys and testing cosmological models. We present a technique to simultaneously infer redshift distributions and individual redshifts from photometric galaxy catalogues. Our model constructs a piecewise constant representation (effectively a histogram) of the distribution of galaxy types and redshifts, the parameters of which are efficiently inferred from noisy photometric flux measurements. This approach can be seen as a generalization of template-fitting photometric redshift methods and relies on a library of spectral templates to relate the photometric fluxes of individual galaxies to their redshifts. We illustrate this technique on simulated galaxy survey data, and demonstrate that it delivers correct posterior distributions on the underlying type and redshift distributions, as well as on the individual types and redshifts of galaxies. We show that even with uninformative priors, large photometri...

  7. Galaxies at High Redshift and Reionization

    CERN Document Server

    Bunker, Andrew; Ellis, Richard; Lacy, Mark; McMahon, Richard; Eyles, Laurence; Stark, Daniel; Chiu, Kuenley

    2009-01-01

    The quest to discover the most distant galaxies has developed rapidly in the last decade. We are now exploring redshifts of 6 and beyond, when the Universe was less than a billion years old, an epoch when the previously-neutral intergalactic medium was reionized. The continuing discovery of galaxies at progressively higher and higher redshifts has been driven by the availability of large telescopes on the ground and in space, improvements in detector technology, and new search strategies. Over the past 4 years, the Lyman break technique has been shown to be effective in isolating z~6 star-forming i'-drop galaxies through spectroscopic confirmation with large ground-based telescopes (Keck, Gemini and the ESO VLTs). Narrow-band imaging, notably with the wide field of the Subaru telescope, has also produced samples of Lyman-alpha emitters at these redshifts. A The discovery of this i'-drop galaxy population has been used to infer the global star formation rate density at this epoch (z~6), and we are now beginnin...

  8. The DEEP Groth Strip Galaxy Redshift Survey. III. Redshift Catalog and Properties of Galaxies

    CERN Document Server

    Weiner, B J; Faber, S M; Willmer, C N A; Vogt, N P; Simard, L; Gebhardt, K; Im, M; Koo, D C; Sarajedini, V L; Wu, K L; Forbes, D A; Gronwall, C; Groth, E J; Illingworth, G D; Kron, R G; Rhodes, J; Szalay, A S; Takamiya, M; Weiner, Benjamin J.; Phillips, Andrew C.; Willmer, Christopher N.A.; Vogt, Nicole P.; Simard, Luc; Gebhardt, Karl; Im, Myungshin; Sarajedini, Vicki L.; Wu, Katherine L.; Forbes, Duncan A.; Gronwall, Caryl; Groth, Edward J.; Rhodes, Jason

    2004-01-01

    The Deep Extragalactic Evolutionary Probe (DEEP) is a series of spectroscopic surveys of faint galaxies, targeted at the properties and clustering of galaxies at redshifts z ~ 1. We present the redshift catalog of the DEEP 1 GSS pilot phase of this project, a Keck/LRIS survey in the HST/WFPC2 Groth Survey Strip. The redshift catalog and data, including reduced spectra, are publicly available through a Web-accessible database. The catalog contains 658 secure galaxy redshifts with a median z=0.65, and shows large-scale structure walls to z = 1. We find a bimodal distribution in the galaxy color-magnitude diagram which persists to z = 1. A similar color division has been seen locally by the SDSS and to z ~ 1 by COMBO-17. For red galaxies, we find a reddening of only 0.11 mag from z ~ 0.8 to now, about half the color evolution measured by COMBO-17. We measure structural properties of the galaxies from the HST imaging, and find that the color division corresponds generally to a structural division. Most red galaxi...

  9. The Merger Rate to Redshift One from Kinematic Pairs Caltech Faint Galaxy Redshift Survey XI

    CERN Document Server

    Carlberg, R G; Patton, D R; Blandford, R D; Hogg, D W; Yee, H K C; Morris, S L; Lin, H; Cowie, L L; Hu, E; Songaila, A; Cohen, Judith G.; Blandford, Roger; Hogg, David W.; Cowie, Lennox L.; Hu, Esther; Songaila, Antoinette

    2000-01-01

    The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator which is relatively insensitive to population evolution. Here we use a k-corrected and evolution compensated volume-limited sample drawing about 300 redshifts from CFGRS and 3000 from CNOC2 to measure the rate and redshift evolution of merging. We identify kinematic pairs with projected separations less than either 50 or 100 \\hkpc and rest-frame velocity differences of less than 1000\\kms. The fractional luminosity in pairs is modeled as f_L(Delta v,r_p,M_r^{ke})(1+z)^{m_L} where [f_L,m_L] are [0.14+/-0.07,0+/-1.4] and [0.37+/-0.7,0.1+/-0.5] for r_p= 0.2 M*) is 0.02+/-0.01(1+z)^{0.1+/-0.5} M*~Gyr^{-1}. Present day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift one. (abridged)

  10. Galaxy Clustering in Early SDSS Redshift Data

    CERN Document Server

    Zehavi, I.; Frieman, Joshua A.; Weinberg, David H.; Mo, Houjun J.; Anderson, Scott F.; Strauss, Michael A.; Annis, James; Bahcall, Neta A.; Bernardi, Mariangela; Briggs, John W.; Brinkmann, Jon; Burles, Scott; Carey, Larry; Castander, Francisco J.; Connolly, J.; Csabai, Istvan; Dalcanton, Julianne J.; Dodelson,Scott; Doi,Mamoru; Eisenstein, Daniel; Evans, Michael L.; Finkbeiner, Douglas P.; Friedman, Scott; Fukugita, Masataka; Gunn, James E.; Hennessy, Greg S.; Hindsley, Robert B.; Ivezic, Zeljko; Kent,Stephen; Knapp, Gillian R.; Kron, Richard; Kunszt, Peter; Lamb, Donald; French Leger, R.; Long, Daniel C.; Loveday, Jon.; Lupton, Robert H.; McKay, Timothy; Meiksin, Avery; Merrelli, Aronne; Munn, Jeffrey A.; Narayanan, Vijay; Newcomb, Matt; Nichol, Robert C.; Owen, Russell; Peoples, John; Pope, Adrian; Rockosi, Constance M.; Schlegel, David; Schneider, Donald P.; Scoccimarro, Roman; Sheth, Ravi K.; Siegmund, Walter; Smee, Stephen; Snir, Yehuda; Stebbins, Albert; Stoughton, Christopher; SubbaRao, Mark; Szalay, Alexander S.; Szapudi, Istvan; Tegmark, Max; Tucker, Douglas L.; Uomoto, Alan; Vanden Berk, Dan; Vogeley, Michael S.; Waddell,Patrick; Yanny, Brian; York, Donald G.; Zehavi, Idit; Blanton, Michael R.; Frieman, Joshua A.; Weinberg, David H.; Mo, Houjun J.; Strauss, Michael A.

    2002-01-01

    We present the first measurements of clustering in the Sloan Digital Sky Survey (SDSS) galaxy redshift survey. Our sample consists of 29,300 galaxies with redshifts 5,700 km/s < cz < 39,000 km/s, distributed in several long but narrow (2.5-5 degree) segments, covering 690 square degrees. For the full, flux-limited sample, the redshift-space correlation length is approximately 8 Mpc/h. The two-dimensional correlation function \\xi(r_p,\\pi) shows clear signatures of both the small-scale, ``fingers-of-God'' distortion caused by velocity dispersions in collapsed objects and the large-scale compression caused by coherent flows, though the latter cannot be measured with high precision in the present sample. The inferred real-space correlation function is well described by a power law, \\xi(r)=(r/6.1+/-0.2 Mpc/h)^{-1.75+/-0.03}, for 0.1 Mpc/h < r < 16 Mpc/h. The galaxy pairwise velocity dispersion is \\sigma_{12} ~ 600+/-100 km/s for projected separations 0.15 Mpc/h < r_p < 5 Mpc/h. When we divide the...

  11. Compact Quiescent Galaxies at Intermediate Redshifts

    CERN Document Server

    Hsu, Li-Yen; Shih, Hsin-Yi

    2014-01-01

    From several searches of the area common to the Sloan Digital Sky Survey and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we have identified objects that have properties similar to those of the luminous quiescent compact galaxies found at z > 2. Here we present our results of 22 galaxies between z ~ 0.4 and z ~ 0.9 based on observations with the Keck I, Keck II and Subaru telescopes on Mauna Kea. By exploring sizes, morphologies, and stellar populations of these galaxies, we found that most of the galaxies we identified actually formed most of their stars at z 2 in the literature. Several of these young objects appear to be disk-like or possibly prolate. This lines up with several previous studies, which found that massive quiescent galaxies at high redshifts often have disk-like morphologies. If these galaxies were to be confirmed to be disks, their formation would be more likely caused by gas accretion than by major mergers. On the other hand, if these galaxies were to be confirmed to be...

  12. Study of GRBs Hosts Galaxies Vicinity Properties

    Science.gov (United States)

    Bernal, S.; Vasquez, N.; Hoyle, F.

    2017-07-01

    The study of GRBs host galaxies and its vicinity could provide constrains on the progenitor and an opportunity to use these violent explosions to characterize the nature of the highredshift universe. Studies of GRB host galaxies reveal a population of starforming galaxies with great diversity, spanning a wide range of masses, star formation rate, and redshifts. In order to study the galactic ambient of GRBs we used the S. Savaglio catalog from 2015 where 245 GRBs are listed with RA-Dec position and z. We choose 22 GRBs Hosts galaxies from Savaglio catalog and SDSS DR12, with z range 0work we provide characteristics on the regions for future works related with highredsift universe that using the GRBs.

  13. Host Galaxy Identification for Supernova Surveys

    CERN Document Server

    Gupta, Ravi R; Kovacs, Eve; Spinka, Harold; Kessler, Richard; Goldstein, Daniel A; Liotine, Camille; Pomian, Katarzyna; D'Andrea, Chris B; Sullivan, Mark; Carretero, Jorge; Castander, Francisco J; Nichol, Robert C; Finley, David A; Fischer, John A; Foley, Ryan J; Kim, Alex G; Papadopoulos, Andreas; Sako, Masao; Scolnic, Daniel M; Smith, Mathew; Tucker, Brad E; Uddin, Syed; Wolf, Rachel C; Yuan, Fang; Abbott, Tim M C; Abdalla, Filipe B; Benoit-Levy, Aurelien; Bertin, Emmanuel; Brooks, David; Rosell, Aurelio Carnero; Kind, Matias Carrasco; Cunha, Carlos E; da Costa, Luiz N; Desai, Shantanu; Doel, Peter; Eifler, Tim F; Evrard, August E; Flaugher, Brenna; Fosalba, Pablo; Gaztanaga, Enrique; Gruen, Daniel; Gruendl, Robert; James, David J; Kuehn, Kyler; Kuropatkin, Nikolay; Maia, Marcio A G; Marshall, Jennifer L; Miquel, Ramon; Plazas, Andres A; Romer, A Kathy; Sanchez, Eusebio; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Sobreira, Flavia; Suchyta, Eric; Swanson, Molly E C; Tarle, Gregory; Walker, Alistair R; Wester, William

    2016-01-01

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST), which will discover SNe by the thousands. Spectroscopic resources are limited, so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated alg...

  14. The Spatial Distribution of Satellite Galaxies Selected from Redshift Space

    CERN Document Server

    Agustsson, Ingolfur

    2015-01-01

    We investigate the spatial distribution of satellite galaxies that were obtained from a mock redshift survey of the first Millennium Run simulation. The satellites were identified using typical redshift space criteria and, hence, the sample includes both genuine satellites and a large number of interlopers. As expected from previous work, the 3D locations of the satellites are well-fitted by a combination of a Navarro, Frenk & White (NFW) density profile and a power law. At fixed stellar mass, the NFW scale parameter, r_s, for the satellite distribution of red hosts exceeds that for the satellite distribution of blue hosts. In both cases the dependence of r_s on host stellar mass is well-fitted by a power law. For the satellites of red hosts, r_s^{red} \\propto (M_\\ast / M_sun)^{0.71 \\pm 0.05} while for the satellites of blue hosts, r_s^{blue} \\propto (M_\\ast / M_sun)^{0.48 \\pm 0.07}. For hosts with stellar masses greater than 4.0E+10 M_sun, the satellite distribution around blue hosts is much more concent...

  15. Statistical Properties of Gamma-Ray Burst Host Galaxies

    Indian Academy of Sciences (India)

    Jie-Min Chen; Jin Zhang; Lan-Wei Jia; En-Wei Liang

    2014-09-01

    A statistical analysis of gamma-ray burst host galaxies is presented and a clear metallicity-stellar mass relation is found in our sample. A trend that a more massive host galaxy tends to have a higher star-formation rate is also found. No correlation is found between V and H. GRB host galaxies at a higher redshift also tend to have a higher star formation rate, however, even in the same redshift, the star formation rate may vary for three orders of magnitude.

  16. VizieR Online Data Catalog: Galaxy Redshifts (Rood 1980)

    Science.gov (United States)

    Rood, H. J.

    1995-10-01

    The Catalog of Galaxy Redshifts was compiled by Dr. Rood to enter the most accurate redshift for each entry in the Uppsala General Catalog of Galaxies below 15000 km/s, plus some fainter galaxies in the fields of rich clusters, plus some southern galaxies. The catalog is 99 percent complete for declinations north of -2.5deg and blue magnitude (Pmag) brighter than 13. The present documentation is mostly adapted from the "Documentation of the Machine-Readable Version of the Catalog of Galaxy Redshifts" by Theresa A. Nagy and Robert S. Hill, May 1981, prepared for NASA GSFC, Greenbelt, No SSD-T-5069-0013-81. (1 data file).

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

    Science.gov (United States)

    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

  18. The fate of high-redshift massive compact galaxies

    CERN Document Server

    de la Rosa, Ignacio G; Ferreras, Ignacio; Almeida, Jorge Sánchez; Vecchia, Claudio Dalla; Martínez-Valpuesta, Inma; Stringer, Martin

    2016-01-01

    Massive high-redshift quiescent compact galaxies (nicknamed red nuggets) have been traditionally connected to present-day elliptical galaxies, often overlooking the relationships that they may have with other galaxy types. We use large bulge-disk decomposition catalogues based on the Sloan Digital Sky Survey (SDSS) to check the hypothesis that red nuggets have survived as compact cores embedded inside the haloes or disks of present-day massive galaxies. In this study, we designate a "compact core" as the bulge component that satisfies a prescribed compactness criterion. Photometric and dynamic mass-size and mass-density relations are used to show that, in the inner regions of galaxies at z ~ 0.1, there are "abundant" compact cores matching the peculiar properties of the red nuggets, an abundance comparable to that of red nuggets at z ~ 1.5. Furthermore, the morphology distribution of the present-day galaxies hosting compact cores is used to demonstrate that, in addition to the standard channel connecting red ...

  19. Galaxy Merger Candidates in High-redshift Cluster Environments

    Science.gov (United States)

    Delahaye, A. G.; Webb, T. M. A.; Nantais, J.; DeGroot, A.; Wilson, G.; Muzzin, A.; Yee, H. K. C.; Foltz, R.; Noble, A. G.; Demarco, R.; Tudorica, A.; Cooper, M. C.; Lidman, C.; Perlmutter, S.; Hayden, B.; Boone, K.; Surace, J.

    2017-07-01

    We compile a sample of spectroscopically and photometrically selected cluster galaxies from four high-redshift galaxy clusters (1.59contamination from interlopers, {11.0}-5.6+7.0 % of the cluster members are involved in potential mergers, compared to {24.7}-4.6+5.3 % of the field galaxies. We see no evidence of merger enhancement in the central cluster environment with respect to the field, suggesting that galaxy-galaxy merging is not a stronger source of galaxy evolution in cluster environments compared to the field at these redshifts.

  20. Galaxy clustering with photometric surveys using PDF redshift information

    Science.gov (United States)

    Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; Brunner, R. J.; Thaler, J.

    2016-06-01

    Photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colours, that are obtained through multiband imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths are Δz = 0.1, the use of the entire PDF reduces the typical measurement bias from 5 per cent, when using single point estimates, to 3 per cent.

  1. Galaxy clustering with photometric surveys using PDF redshift information

    CERN Document Server

    Asorey, J; Sevilla-Noarbe, I; Brunner, R J; Thaler, J

    2016-01-01

    Photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colors, that are obtained through multi-band imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths are $\\Delta z=0.1$, the use of the entire PDF reduces the typical measurement bias from 5%, when using single point estimates, to 3%.

  2. The DEEP2 Galaxy Redshift Survey: Redshift Identification of Single-Line Emission Galaxies

    CERN Document Server

    Kirby, E N; Faber, S M; Koo, D C; Weiner, B J; Cooper, M C

    2007-01-01

    We present two methods for determining spectroscopic redshifts of galaxies in the \\deep survey which display only one identifiable feature, an emission line, in the observed spectrum ("single-line galaxies"). First, we assume each single line is one of the four brightest lines accessible to DEEP2: Halpha, [OIII] 5007, Hbeta, or [OII] 3727. Then, we supplement spectral information with BRI photometry. The first method, parameter space proximity (PSP), calculates the distance of a single-line galaxy to galaxies of known redshift in (B-R), (R-I), R, observed wavelength parameter space. The second method is an artificial neural network (ANN). Prior information, such as allowable line widths and ratios, rules out one or more of the four lines for some galaxies in both methods. Based on analyses of evaluation sets, both methods are nearly perfect at identifying blended [OII] doublets. Of the lines identified as Halpha in the PSP and ANN methods, 91.4% and 94.2% respectively are accurate. Although the methods are no...

  3. Calibrating galaxy redshifts using absorption by the surrounding intergalactic medium

    Science.gov (United States)

    Rakic, Olivera; Schaye, Joop; Steidel, Charles C.; Rudie, Gwen C.

    2011-07-01

    Rest-frame UV spectral lines of star-forming galaxies are systematically offset from the galaxies' systemic redshifts, probably because of large-scale outflows. We calibrate galaxy redshifts measured from rest-frame UV lines by utilizing the fact that the mean H I Lyα absorption profiles around the galaxies, as seen in spectra of background objects, must be symmetric with respect to the true galaxy redshifts if the galaxies are oriented randomly with respect to the lines of sight to the background objects. We use 15 bright QSOs at z≈ 2.5-3 and more than 600 foreground galaxies with spectroscopic redshifts at z≈ 1.9-2.5. All galaxies are within 2 Mpc proper from the lines of sight to the background QSOs. We find that Lyα emission and ISM absorption redshifts require systematic shifts of ? and ?, respectively. Assuming a Gaussian distribution, we put 1σ upper limits on possible random redshift offsets of ? for Lyα and ? for ISM redshifts. For the small subset (Technology, the University of California and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kaufmann, Tobias; /Zurich, ETH; Mayer, Lucio; /Zurich U.; Carollo, Marcella; /Zurich, ETH; 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.

  5. A Fast Radio Burst Host Galaxy

    CERN Document Server

    Keane, E F; Bhandari, S; Barr, E; Bhat, N D R; Burgay, M; Caleb, M; Flynn, C; Jameson, A; Kramer, M; Petroff, E; Possenti, A; van Straten, W; Bailes, M; Burke-Spolaor, S; Eatough, R P; Stappers, B W; Totani, T; Honma, M; Furusawa, H; Hattori, T; Morokuma, T; Niino, Y; Sugai, H; Terai, T; Tominaga, N; Yamasaki, S; Yasuda, N; Allen, R; Cooke, J; Jencson, J; Kasliwal, M M; Kaplan, D L; Tingay, S J; Williams, A; Wayth, R; Chandra, P; Perrodin, D; Berezina, M; Mickaliger, M; Bassa, C

    2016-01-01

    In recent years, millisecond duration radio signals originating from distant galaxies appear to have been discovered in the so-called Fast Radio Bursts. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity which, in tandem with a redshift measurement, can be used for fundamental physical investigations. While every fast radio burst has a dispersion measurement, none before now have had a redshift measurement, due to the difficulty in pinpointing their celestial coordinates. Here we present the discovery of a fast radio burst and the identification of a fading radio transient lasting $\\sim 6$ days after the event, which we use to identify the host galaxy; we measure the galaxy's redshift to be $z=0.492\\pm0.008$. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionised baryons in the intergalactic medium of $\\Omega_{\\mathrm{IGM}}=4.9 \\pm 1.3\\%$, in agreement with the expectation from WMAP, and i...

  6. Photometric redshifts and selection of high redshift galaxies in the NTT and Hubble Deep Fields

    CERN Document Server

    Fontana, A; Poli, F; Giallongo, E; Arnouts, S; Cristiani, S; Moorwood, A F M; Saracco, P

    2000-01-01

    We present and compare in this paper new photometric redshift catalogs of the galaxies in three public fields: the NTT Deep Field, the HDF-N and the HDF-S. Photometric redshifts have been obtained for thewhole sample, by adopting a $\\chi^2$ minimization technique on a spectral library drawn from the Bruzual and Charlot synthesis models, with the addition of dust and intergalactic absorption. The accuracy, determined from 125 galaxies with known spectroscopic redshifts, is $\\sigma_z\\sim 0.08 (0.3)$ in the redshift intervals $z=0-1.5 (1.5-3.5)$. The global redshift distribution of I-selected galaxies shows a distinct peak at intermediate redshifts, z~0.6 at I_{AB}5 candidates in the HDF filter set and that the 4 brightest candidates at $z>5$ in the HDF-S are indeed most likely M stars. (ABRIDGED)

  7. High-Redshift Radio Galaxies from Deep Fields

    Indian Academy of Sciences (India)

    C. H. Ishwara-Chandra; S. K. Sirothia; Y. Wadadekar; S. Pal

    2011-12-01

    Most of the radio galaxies with > 3 have been found using the red-shift spectral index correlation.We have started a programme with the Giant Metrewave Radio Telescope (GMRT) to exploit this correlation at flux density levels about 100 times deeper than the known high-redshift radio galaxies, with an aim to detect candidate high-redshift radio galaxies. Here we present results from the deep 150 MHz observations of LBDS-Lynx field, which has been imaged at 327, 610 and 1412 MHz with the Westerbork Synthesis Radio Telescope (WSRT) and at 1400 and 4860 MHz with the Very Large Array (VLA). We find about 150 radio sources with spectra steeper than 1. About two-thirds of these are not detected in Sloan Digital Sky Survey (SDSS), hence are strong candidate high-redshift radio galaxies, which need to be further explored with deep infra-red imaging and spectroscopy to estimate the red-shift.

  8. The Smallest AGN Host Galaxies

    CERN Document Server

    Greene, J E; Ho, L C

    2005-01-01

    We describe our efforts to study dwarf galaxies with active nuclei, whose black holes, with masses < 10^6 M_sun, provide the best current observational constraints on the mass distribution of primordial seed black holes. Although these low-mass galaxies do not necessarily contain classical bulges, Barth, Greene, & Ho (2005) show that their stellar velocity dispersions and black hole masses obey the same relation as more massive systems. In order to characterize the properties of the dwarf hosts without the glare of the active nucleus, we have compiled a complementary sample of narrow-line active galaxies with low-mass hosts. The host galaxy properties, both their structures and stellar populations, are consistent with the general properties of low-mass, blue galaxies from Sloan. The black holes in these galaxies are probably radiating close to their Eddington limits, suggesting we may have found Type 2 analogues of narrow-line Seyfert 1 galaxies.

  9. Photometric redshifts of galaxies from SDSS and 2MASS

    Institute of Scientific and Technical Information of China (English)

    Tao Wang; Jia-Sheng Huang; Qiu-Sheng Gu

    2009-01-01

    In order to find the physical parameters which determine the accuracy of pho- tometric redshifts, we compare the spectroscopic and photometric redshifts (photo-z's) for a large sample of ~ 80 000 SDSS-2MASS galaxies. Photo-z's in this paper are es- timated by using the artificial neural network photometric redshift method (ANNz). For a subset of~40000 randomly selected galaxies, we find that the photometric redshift recovers the spectroscopic redshifi distribution very well with rms of 0.016. Our main results are as follows: (1) Using magnitudes directly as input parameters produces more accurate photo-z's than using colors; (2) The inclusion of 2MASS (3, H, Ks) bands does not improve photo-z's significantly, which indicates that near infrared data might not be important for the low-redshift sample; (3) Adding the concentration index (essentially the steepness of the galaxy brightness profile) as an extra input can improve the photo-z's estimation up to~10 percent; (4) Dividing the sample into early- and late-type galaxies by using the concentration index, normal and abnormal galaxies by using the emission line flux ratios, and red and blue galaxies by using color index (g - r), we can improve the accuracy of photo-z's significantly; (5) Our analysis shows that the outliers (where there is a big difference between the spectroscopic and photometric redshifts) are mainly correlated with galaxy types, e.g., most outliers are late-type (blue) galaxies.

  10. The formation and evolution of high-redshift dusty galaxies

    Science.gov (United States)

    Ma, Jingzhe; Gonzalez, Anthony H.; Ge, Jian; Vieira, Joaquin D.; Prochaska, Jason X.; Spilker, Justin; Strandet, Maria; Ashby, Matthew; Noterdaeme, Pasquier; Lundgren, Britt; Zhao, Yinan; Ji, Tuo; Zhang, Shaohua; Caucal, Paul; SPT SMG Collaboration

    2017-01-01

    Star formation and chemical evolution are among the biggest questions in galaxy formation and evolution. High-redshift dusty galaxies are the best sites to investigate mass assembly and growth, star formation rates, star formation history, chemical enrichment, and physical conditions. My thesis is based on two populations of high-redshift dusty galaxies, submillimeter galaxies (SMGs) and quasar 2175 Å dust absorbers, which are selected by dust emission and dust absorption, respectively.For the SMG sample, I have worked on the gravitationally lensed dusty, star-forming galaxies (DSFGs) at 2.8 thesis is focused on the stellar masses and star formation rates of these objects by means of multi-wavelength spectral energy distribution (SED) modelling. The data include HST/WFC3, Spitzer/IRAC, Herschel/PACS, Herschel/SPIRE, APEX/Laboca and SPT. Compared to the star-forming main sequence (MS), these DSFGs have specific SFRs that lie above the MS, suggesting that we are witnessing ongoing strong starburst events that may be driven by major mergers. SPT0346-52 at z = 5.7, the most extraordinary source in the SPT survey for which we obtained Chandra X-ray and ATCA radio data, was confirmed to have the highest star formation surface density of any known galaxy at high-z.The other half of my thesis is focused on a new population of quasar absorption line systems, 2175 Å dust absorbers, which are excellent probes of gas and dust properties, chemical evolution and physical conditions in the absorbing galaxies. This sample was selected from the SDSS and BOSS surveys and followed up with the Echelle Spectrographs and Imager on the Keck-II telescope, the Red & Blue Channel Spectrograph on the Multiple Mirror Telescope, and the Ultraviolet and Visible Echelle Spectrograph onboard the Very Large Telescope. We found a correlation between the presence of the 2175 Å bump and other ingredients including high metallicity, high depletion level, overall low ionization state of gas, neutral

  11. Host Galaxy Spectra and Consequences for SN Typing from the SDSS SN Survey

    Energy Technology Data Exchange (ETDEWEB)

    Olmstead, Matthew D.; Brown, Peter J.; Sako, Masao; Bassett, Bruce; Bizyaev, Dmitry; Brinkmann, J.; Brownstein, Joel R.; Brewington, Howard; Campbell, Heather; D’Andrea, Chris B.; Dawson, Kyle S.; Ebelke, Garrett L.; Frieman, Joshua A.; Galbany, Lluís; Garnavich, Peter; Gupta, Ravi R.; Hlozek, Renee; Jha, Saurabh W.; Kunz, Martin; Lampeitl, Hubert; Malanushenko, Elena; Malanushenko, Viktor; Marriner, John; Miquel, Ramon; Montero-Dorta, Antonio D.; Nichol, Robert C.; Oravetz, Daniel J.; Pan, Kaike; Schneider, Donald P.; Simmons, Audrey E.; Smith, Mathew; Snedden, Stephanie A.

    2014-03-06

    We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe) or other transient events in the Sloan Digital Sky Survey II (SDSS-II). Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic Survey (BOSS), this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of supernova (SN) host galaxies. Using the host galaxy redshifts, we test the impact of photometric SN classification based on SDSS imaging data with and without using spectroscopic redshifts of the host galaxies. Following our suggested scheme, there are a total of 1166 photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates classified as likely SNe Ia without redshift information, we find that the classification is unchanged when adding the host galaxy redshift. Using photometry from SDSS imaging data and the host galaxy spectra, we also report host galaxy properties for use in future nalysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. When using the SALT2 light curve fitter, we find a 21% increase in the number of fits that converge when using the spectroscopic redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased towards lower photometric redshift estimates and redder colors in the limit of low signal-to-noise data. The general improvements in performance of the light curve fitter and the increased diversity of the host galaxy sample highlights the importance of host galaxy spectroscopy for current photometric SN surveys such as the Dark Energy Survey and future surveys such as the Large Synoptic Survey Telescope.

  12. Mapping the Galaxy Color-Redshift Relation: Optimal Photometric Redshift Calibration Strategies for Cosmology Surveys

    CERN Document Server

    Masters, Daniel; Stern, Daniel; Ilbert, Olivier; Salvato, Mara; Schmidt, Samuel; Longo, Giuseppe; Rhodes, Jason; Paltani, Stephane; Mobasher, Bahram; Hoekstra, Henk; Hildebrandt, Hendrik; Coupon, Jean; Steinhardt, Charles; Speagle, Josh; Faisst, Andreas; Kalinich, Adam; Brodwin, Mark; Brescia, Massimo; Cavuoti, Stefano

    2015-01-01

    Calibrating the photometric redshifts of >10^9 galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths of the surveys and the difficulty in obtaining secure redshifts for some faint galaxy populations. Here we present an analysis of the problem based on the self-organizing map, a method of mapping the distribution of data in a high-dimensional space and projecting it onto a lower-dimensional representation. We apply this method to existing photometric data from the COSMOS survey selected to approximate the anticipated Euclid weak lensing sample, enabling us to robustly map the empirical distribution of galaxies in the multidimensional color space defined by the expected Euclid filters. Mapping this multicolor distribution lets us determine where - in galaxy color space - redshifts from current spectroscopic surveys exist and whe...

  13. Measuring photometric redshifts using galaxy images and Deep Neural Networks

    Science.gov (United States)

    Hoyle, B.

    2016-07-01

    We propose a new method to estimate the photometric redshift of galaxies by using the full galaxy image in each measured band. This method draws from the latest techniques and advances in machine learning, in particular Deep Neural Networks. We pass the entire multi-band galaxy image into the machine learning architecture to obtain a redshift estimate that is competitive, in terms of the measured point prediction metrics, with the best existing standard machine learning techniques. The standard techniques estimate redshifts using post-processed features, such as magnitudes and colours, which are extracted from the galaxy images and are deemed to be salient by the user. This new method removes the user from the photometric redshift estimation pipeline. However we do note that Deep Neural Networks require many orders of magnitude more computing resources than standard machine learning architectures, and as such are only tractable for making predictions on datasets of size ≤50k before implementing parallelisation techniques.

  14. Exploring the SDSS photometric galaxies with clustering redshifts

    Science.gov (United States)

    Rahman, Mubdi; Mendez, Alexander J.; Ménard, Brice; Scranton, Ryan; Schmidt, Samuel J.; Morrison, Christopher B.; Budavári, Tamás

    2016-07-01

    We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We map the relationships between colours and redshift, without assumption of the sources' spectral energy distributions (SEDs). We identify and locate star-forming quiescent galaxies, and active galactic nuclei, as well as colour changes due to spectral features, such as the 4000 Å break, redshifting through specific filters. Our mapping is globally in good agreement with colour-redshift tracks computed with SED templates, but reveals informative differences, such as the need for a lower fraction of M-type stars in certain templates. We compare our clustering-redshift estimates to photometric redshifts and find these two independent estimators to be in good agreement at each limiting magnitude considered. Finally, we present the global clustering-redshift distribution of all Sloan extended sources, showing objects up to z ˜ 0.8. While the overall shape agrees with that inferred from photometric redshifts, the clustering-redshift technique results in a smoother distribution, with no indication of structure in redshift space suggested by the photometric-redshift estimates (likely artefacts imprinted by their spectroscopic training set). We also infer a higher fraction of high-redshift objects. The mapping between the four observed colours and redshift can be used to estimate the redshift probability distribution function of individual galaxies. This work is an initial step towards producing a general mapping between redshift and all available observables in the photometric space, including brightness, size, concentration, and ellipticity.

  15. The Coevolution of Supermassive Black Holes and Massive Galaxies at High Redshift

    Science.gov (United States)

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

    2014-02-01

    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 generation X-ray instruments.

  16. Dynamical Analyses of Galaxy Clusters With Large Redshift Samples

    Science.gov (United States)

    Mohr, J. J.; Richstone, D. O.; Wegner, G.

    1998-12-01

    We construct equilibrium models of galaxy orbits in five nearby galaxy clusters to study the distribution of binding mass, the nature of galaxy orbits and the kinematic differences between cluster populations of emission-line and non emission-line galaxies. We avail ourselves of 1718 galaxy redshifts (and 1203 cluster member redshifts) in this Jeans analysis; most of these redshifts are new, coming from multifiber spectroscopic runs on the MDM 2.4m with the Decaspec and queue observing on WIYN with Hydra. In addition to the spectroscopic data we have V and R band CCD mosaics (obtained with the MDM 1.3m) of the Abell region in each of these clusters. Our scientific goals include: (i) a quantitative estimate of the range of binding masses M500 consistent with the optical and X-ray data, (ii) an estimate of the typical galaxy oribital anisotropies required to make the galaxy data consistent with the NFW expectation for the cluster potential, (iii) a better understanding of the systematics inherent in the process of rescaling and ``stacking'' galaxy cluster observations, (iv) a reexamination of the recent CNOC results implying that emission-line (blue) galaxies are an equilibrium population with a more extended radial distribution than their non emission-line (red) galaxy counterparts and (v) a measure of the galaxy contribution to the cluster mass of baryons.

  17. Galaxy groups in the low-redshift Universe

    Science.gov (United States)

    Lim, S. H.; Mo, H. J.; Lu, Yi; Wang, Huiyuan; Yang, Xiaohu

    2017-09-01

    We apply a halo-based group finder to four large redshift surveys, the 2MRS (Two Micron All-Sky Redshift Survey), 6dFGS (Six-degree Field Galaxy Survey), SDSS (Sloan Digital Sky Survey) and 2dFGRS (Two-degree Field Galaxy Redshift Survey), to construct group catalogues in the low-redshift Universe. The group finder is based on that of Yang et al. but with an improved halo mass assignment so that it can be applied uniformly to various redshift surveys of galaxies. Halo masses are assigned to groups according to proxies based on the stellar mass/luminosity of member galaxies. The performances of the group finder in grouping galaxies according to common haloes and in halo mass assignments are tested using realistic mock samples constructed from hydrodynamical simulations and empirical models of galaxy occupation in dark matter haloes. Our group finder finds ∼94 per cent of the correct true member galaxies for 90-95 per cent of the groups in the mock samples; the halo masses assigned by the group finder are un-biased with respect to the true halo masses, and have a typical uncertainty of ∼0.2 dex. The properties of group catalogues constructed from the observational samples are described and compared with other similar catalogues in the literature.

  18. Exploring the SDSS Photometric Galaxies with Clustering Redshifts

    CERN Document Server

    Rahman, Mubdi; Ménard, Brice; Scranton, Ryan; Schmidt, Samuel J; Morrison, Christopher B; Budavári, Tamás

    2015-01-01

    We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We map the relationships between colours and redshift, without assumption of the sources' spectral energy distributions (SED). We identify and locate star-forming, quiescent galaxies, and AGN, as well as colour changes due to spectral features, such as the 4000 \\AA{} break, redshifting through specific filters. Our mapping is globally in good agreement with colour-redshift tracks computed with SED templates, but reveals informative differences, such as the need for a lower fraction of M-type stars in certain templates. We compare our clustering-redshift estimates to photometric redshifts and find these two independent estimators to be in good agreement at each limiting magnitude considered. Finally, we present the global clustering-redshift distribution of all Sloan extended sources, showing objects up to z ~ 0.8. While the overall shape agrees with that infer...

  19. Population synthesis and the diagnostics of high-redshift galaxies

    Science.gov (United States)

    Buzzoni, Alberto

    The effect of redshift on the observation of distant galaxies is briefly discussed emphasizing the possible sources of bias in the interpretation of high-z data. A general energetic criterion to assess physical self-consistency of evolutionary population synthesis models is also proposed, for a more appropriate use of this important tool to investigate distinctive properties of primeval galaxies.

  20. Population Synthesis and the Diagnostics of High-redshift Galaxies

    OpenAIRE

    Buzzoni, Alberto

    2001-01-01

    The effect of redshift on the observation of distant galaxies is briefly discussed emphasizing the possible sources of bias in the interpretation of high-z data. A general energetic criterion to assess physical self-consistency of evolutionary population synthesis models is also proposed, for a more appropriate use of this important tool to investigate distinctive properties of primeval galaxies.

  1. Clustering of supernova Ia host galaxies

    CERN Document Server

    Carlberg, R G; Le Borgne, D; Conley, A; Howell, D A; Perrett, K; Astier, Pierre; Balam, D; Balland, C; Basa, S; Hardin, D; Fouchez, D; Guy, J; Hook, I; Pain, R; Pritchet, C J; Regnault, N; Rich, J; Perlmutter, S

    2008-01-01

    For the first time the cross-correlation between type Ia supernova host galaxies and surrounding field galaxies is measured using the Supernova Legacy Survey sample. Over the z=0.2 to 0.9 redshift range we find that supernova hosts are correlated an average of 60% more strongly than similarly selected field galaxies over the 3-100 arcsec range and about a factor of 3 more strongly below 10 arcsec. The correlation errors are empirically established with a jackknife analysis of the four SNLS fields. The hosts are more correlated than the field at a significance of 99% in the fitted amplitude and slope, with the point-by-point difference of the two correlation functions having a reduced $\\chi^2$ for 8 degrees of freedom of 4.3, which has a probability of random occurrence of less than 3x10^{-5}. The correlation angle is 1.5+/-0.5 arcsec, which deprojects to a fixed co-moving correlation length of approximately 6.5+/- 2/h mpc. Weighting the field galaxies with the mass and star formation rate supernova frequencie...

  2. The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts

    OpenAIRE

    Newman, Jeffrey A.; Kassin, Susan A.; Noeske, K. G.; Lotz, Jennifer M.

    2013-01-01

    We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z ~ 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude M_B = −20 at z ~ 1 via ~90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg^2 divided into four separate fields observed to a l...

  3. MAPPING THE GALAXY COLOR–REDSHIFT RELATION: OPTIMAL PHOTOMETRIC REDSHIFT CALIBRATION STRATEGIES FOR COSMOLOGY SURVEYS

    Energy Technology Data Exchange (ETDEWEB)

    Masters, Daniel; Steinhardt, Charles; Faisst, Andreas [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Capak, Peter [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, Daniel; Rhodes, Jason [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Ilbert, Olivier [Aix Marseille Universite, CNRS, LAM (Laboratoire dAstrophysique de Marseille) UMR 7326, F-13388, Marseille (France); Salvato, Mara [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Schmidt, Samuel [Department of Physics, University of California, Davis, CA 95616 (United States); Longo, Giuseppe [Department of Physics, University Federico II, via Cinthia 6, I-80126 Napoli (Italy); Paltani, Stephane; Coupon, Jean [Department of Astronomy, University of Geneva ch. dcogia 16, CH-1290 Versoix (Switzerland); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Hoekstra, Henk [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden (Netherlands); Hildebrandt, Hendrik [Argelander-Institut für Astronomie, Universität Bonn, Auf dem H’´ugel 71, D-53121 Bonn (Germany); Speagle, Josh [Department of Astronomy, Harvard University, 60 Garden Street, MS 46, Cambridge, MA 02138 (United States); Kalinich, Adam [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Brodwin, Mark [Department of Physics and Astronomy, University of Missouri, Kansas City, MO 64110 (United States); Brescia, Massimo; Cavuoti, Stefano [Astronomical Observatory of Capodimonte—INAF, via Moiariello 16, I-80131, Napoli (Italy)

    2015-11-01

    Calibrating the photometric redshifts of ≳10{sup 9} galaxies for upcoming weak lensing cosmology experiments is a major challenge for the astrophysics community. The path to obtaining the required spectroscopic redshifts for training and calibration is daunting, given the anticipated depths of the surveys and the difficulty in obtaining secure redshifts for some faint galaxy populations. Here we present an analysis of the problem based on the self-organizing map, a method of mapping the distribution of data in a high-dimensional space and projecting it onto a lower-dimensional representation. We apply this method to existing photometric data from the COSMOS survey selected to approximate the anticipated Euclid weak lensing sample, enabling us to robustly map the empirical distribution of galaxies in the multidimensional color space defined by the expected Euclid filters. Mapping this multicolor distribution lets us determine where—in galaxy color space—redshifts from current spectroscopic surveys exist and where they are systematically missing. Crucially, the method lets us determine whether a spectroscopic training sample is representative of the full photometric space occupied by the galaxies in a survey. We explore optimal sampling techniques and estimate the additional spectroscopy needed to map out the color–redshift relation, finding that sampling the galaxy distribution in color space in a systematic way can efficiently meet the calibration requirements. While the analysis presented here focuses on the Euclid survey, similar analysis can be applied to other surveys facing the same calibration challenge, such as DES, LSST, and WFIRST.

  4. High redshift galaxies in the ALHAMBRA survey: I. selection method and number counts based on redshift PDFs

    CERN Document Server

    Viironen, K; López-Sanjuan, C; Varela, J; Chaves-Montero, J; Cristóbal-Hornillos, D; Molino, A; Fernández-Soto, A; Ascaso, B; Cenarro, A J; Cerviño, M; Cepa, J; Ederoclite, A; Márquez, I; Masegosa, J; Moles, M; Oteo, I; Pović, M; Aguerri, J A L; Alfaro, E; Aparicio-Villegas, T; Benítez, N; Broadhurst, T; Cabrera-Caño, J; Castander, J F; Del Olmo, A; Delgado, R M González; Husillos, C; Infante, L; Martínez, V J; Perea, J; Prada, F; Quintana, J M

    2015-01-01

    Context. Most observational results on the high redshift restframe UV-bright galaxies are based on samples pinpointed using the so called dropout technique or Ly-alpha selection. However, the availability of multifilter data allows now replacing the dropout selections by direct methods based on photometric redshifts. In this paper we present the methodology to select and study the population of high redshift galaxies in the ALHAMBRA survey data. Aims. Our aim is to develop a less biased methodology than the traditional dropout technique to study the high redshift galaxies in ALHAMBRA and other multifilter data. Thanks to the wide area ALHAMBRA covers, we especially aim at contributing in the study of the brightest, less frequent, high redshift galaxies. Methods. The methodology is based on redshift probability distribution functions (zPDFs). It is shown how a clean galaxy sample can be obtained by selecting the galaxies with high integrated probability of being within a given redshift interval. However, reach...

  5. Galaxy Halo Occupation at High Redshift

    CERN Document Server

    Bullock, J S; Somerville, R S; Bullock, James S.; Wechsler, Risa H.; Somerville, Rachel S.

    2002-01-01

    We discuss how current and future data on the clustering and number density of z~3 Lyman-break galaxies (LBGs) can be used to constrain their relationship to dark matter haloes. We explore a three-parameter model in which the number of LBGs per dark halo scales like a power-law in the halo mass: N(M) = (M/M_1)^S for M>M_m. Here, M_m is the minimum mass halo that can host an LBG, M_1 is a normalization parameter, associated with the mass above which haloes host more than one observed LBG, and S determines the strength of the mass dependence. We show how these three parameters are constrained by three observable properties of LBGs: the number density, the large-scale bias, and the fraction of objects in close pairs. Given these three quantities, the three unknown model parameters may be estimated analytically, allowing a full exploration of parameter space. As an example, we assume an LCDM cosmology and consider the observed properties of a recent sample of spectroscopically confirmed LBGs. We find that the fav...

  6. Linear redshift space distortions for cosmic voids based on galaxies in redshift space

    CERN Document Server

    Chuang, Chia-Hsun; Liang, Yu; Font-Ribera, Andreu; Zhao, Cheng; McDonald, Patrick; Tao, Charling

    2016-01-01

    Cosmic voids found in galaxy surveys are defined based on the galaxy distribution in redshift space. We show that the large scale distribution of voids in redshift space traces the fluctuations in the dark matter density field \\delta(k) (in Fourier space with \\mu being the line of sight projected k-vector): \\delta_v^s(k) = (1 + \\beta_v \\mu^2) b^s_v \\delta(k), with a beta factor that will be in general different than the one describing the distribution of galaxies. Only in case voids could be assumed to be quasi-local transformations of the linear (Gaussian) galaxy redshift space field, one gets equal beta factors \\beta_v=\\beta_g=f/b_g with f being the growth rate, and b_g, b^s_v being the galaxy and void bias on large scales defined in redshift space. Indeed, in our mock void catalogs we measure void beta factors being in good agreement with the galaxy one. Further work needs to be done to confirm the level of accuracy of the beta factor equality between voids and galaxies, but in general the void beta factor...

  7. The Environment of Galaxies at Low Redshift

    CERN Document Server

    Ivezic, Nicolas B Cowan Zeljko

    2008-01-01

    We compare environmental effects in two analogous samples of galaxies, one from the Sloan Digital Sky Survey (SDSS) and the other from a semi-analytic model (SAM) based on the Millennium Simulation (MS), to test to what extent current SAMs of galaxy formation are reproducing environmental effects. We estimate the large-scale environment of each galaxy using a Bayesian density estimator based on distances to all ten nearest neighbors and compare broad-band photometric properties of the two samples as a function of environment. The feedbacks implemented in the semi-analytic model produce a qualitatively correct galaxy population with similar environmental dependence as that seen in SDSS galaxies. In detail, however, the colors of MS galaxies exhibit an exaggerated dependence on environment: the field contains too many blue galaxies while clusters contain too many red galaxies, compared to the SDSS sample. We also find that the MS contains a population of highly clustered, relatively faint red galaxies with velo...

  8. Population III Stars and Remnants in High Redshift Galaxies

    CERN Document Server

    Xu, Hao; Norman, Michael L

    2013-01-01

    Recent simulations of Population III star formation have suggested that some fraction form in binary systems, in addition to having a characteristic mass of tens of solar masses. The deaths of metal-free stars result in the initial chemical enrichment of the universe and the production of the first stellar-mass black holes. Here we present a cosmological adaptive mesh refinement simulation of an overdense region that forms a few 10^9 Msun dark matter halos and over 13,000 Population III stars by redshift 15. We find that most halos do not form Population III stars until they reach Mvir ~ 10^7 Msun because this biased region is quickly enriched from both Population III and galaxies, which also produce high levels of ultraviolet radiation that suppress H2 formation. Nevertheless, Population III stars continue to form, albeit in more massive halos, at a rate of ~ 10^{-4} Msun yr^{-1} Mpc^{-3} at redshift 15. The most massive starless halo has a mass of 7 x 10^7 Msun, which could host massive black hole formation...

  9. On the Number of Galaxies at High Redshift

    Directory of Open Access Journals (Sweden)

    Lorenzo Zaninetti

    2015-09-01

    Full Text Available The number of galaxies at a given flux as a function of the redshift, z, is derived when the z-distance relation is non-standard. In order to compare different models, the same formalism is also applied to the standard cosmology. The observed luminosity function for galaxies of the zCOSMOS catalog at different redshifts is modeled by a new luminosity function for galaxies, which is derived by the truncated beta probability density function. Three astronomical tests, which are the photometric maximum as a function of the redshift for a fixed flux, the mean value of the redshift for a fixed flux, and the luminosity function for galaxies as a function of the redshift, compare the theoretical values of the standard and non-standard model with the observed value. The tests are performed on the FORS Deep Field (FDF catalog up to redshift z = 1.5 and on the zCOSMOS catalog extending beyond z = 4. These three tests show minimal differences between the standard and the non-standard models.

  10. Local Analogs for High-redshift Galaxies: Resembling the Physical Conditions of the Interstellar Medium in High-redshift Galaxies

    CERN Document Server

    Bian, Fuyan; Dopita, Michael; Juneau, Stephanie

    2016-01-01

    We present a sample of local analogs for high-redshift galaxies selected in the Sloan Digital Sky Survey (SDSS). The physical conditions of the interstellar medium (ISM) in these local analogs resemble those in high-redshift galaxies. These galaxies are selected based on their positions in the [OIII]/H$\\beta$ versus [NII]/H$\\alpha$ nebular emission-line diagnostic diagram. We show that these local analogs share similar physical properties with high-redshift galaxies, including high specific star formation rates (sSFRs), flat UV continuums and compact galaxy sizes. In particular, the ionization parameters and electron densities in these analogs are comparable to those in $z\\simeq2-3$ galaxies, but higher than those in normal SDSS galaxies by $\\simeq$0.6~dex and $\\simeq$0.9~dex, respectively. The mass-metallicity relation (MZR) in these local analogs shows $-0.2$~dex offset from that in SDSS star-forming galaxies at the low mass end, which is consistent with the MZR of the $z\\sim2-3$ galaxies. We compare the lo...

  11. A Low-redshift Sample of E+A Galaxies

    Science.gov (United States)

    Walker, K. M.; Bergmann, M. P.; Turner, J.

    2004-12-01

    We present the results of a low-redshift survey for E+A galaxies. These galaxies are spectroscopically classified as having strong Balmer and metallic absorption with the absence of any emission. The absorption lines indicate an abundance of A-type stars as well as an old stellar population, while the absence of emission, especially {O ii}, denotes the lack of current star formation. Essential in determining the evolution of early-type galaxies, a low-redshift sample will allow easier morphology observations and further spectroscopic study. Fourteen low-redshift E+A galaxies were found using the Sloan Digital Sky Survey Data Release One following similar criteria as the H-delta strong survey of Goto (2003), except that only galaxies with a redshift lower than z=0.05 were selected. Two of these E+A galaxies were observed with the Cerro Tololo Inter-American Observatory 1.5-m telescope and confirmed to have no emission anywhere along the longslit, including outside the 3" region sampled by the SDSS fibers. This work was supported by the NSF through the CTIO REU program.

  12. Galaxy halo occupation at high redshift

    Science.gov (United States)

    Bullock, James S.; Wechsler, Risa H.; Somerville, Rachel S.

    2002-01-01

    We discuss how current and future data on the clustering and number density of z~3 Lyman-break galaxies (LBGs) can be used to constrain their relationship to dark matter haloes. We explore a three-parameter model in which the number of LBGs per dark halo scales like a power law in the halo mass: N(M)=(M/M1)S for M>Mmin. Here, Mmin is the minimum mass halo that can host an LBG, M1 is a normalization parameter, associated with the mass above which haloes host more than one observed LBG, and S determines the strength of the mass-dependence. We show how these three parameters are constrained by three observable properties of LBGs: the number density, the large-scale bias and the fraction of objects in close pairs. Given these three quantities, the three unknown model parameters may be estimated analytically, allowing a full exploration of parameter space. As an example, we assume a ΛCDM cosmology and consider the observed properties of a recent sample of spectroscopically confirmed LBGs. We find that the favoured range for our model parameters is Mmin~=(0.4-8)×1010h- 1Msolar, M1~=(6-10)×1012h- 1Msolar, and 0.9acceptable if the allowed range of bg is permitted to span all recent observational estimates. We also discuss how the observed clustering of LBGs as a function of luminosity can be used to constrain halo occupation, although because of current observational uncertainties we are unable to reach any strong conclusions. Our methods and results can be used to constrain more realistic models that aim to derive the occupation function N(M) from first principles, and offer insight into how basic physical properties affect the observed properties of LBGs.

  13. Tuning target selection algorithms to improve galaxy redshift estimates

    CERN Document Server

    Hoyle, Ben; Rau, Markus Michael; Seitz, Stella; Weller, Jochen

    2015-01-01

    We showcase machine learning (ML) inspired target selection algorithms to determine which of all potential targets should be selected first for spectroscopic follow up. Efficient target selection can improve the ML redshift uncertainties as calculated on an independent sample, while requiring less targets to be observed. We compare the ML targeting algorithms with the Sloan Digital Sky Survey (SDSS) target order, and with a random targeting algorithm. The ML inspired algorithms are constructed iteratively by estimating which of the remaining target galaxies will be most difficult for the machine learning methods to accurately estimate redshifts using the previously observed data. This is performed by predicting the expected redshift error and redshift offset (or bias) of all of the remaining target galaxies. We find that the predicted values of bias and error are accurate to better than 10-30% of the true values, even with only limited training sample sizes. We construct a hypothetical follow-up survey and fi...

  14. Photometric Redshift with Bayesian Priors on Physical Properties of Galaxies

    CERN Document Server

    Tanaka, Masayuki

    2015-01-01

    We present a proof-of-concept analysis of photometric redshifts with Bayesian priors on physical properties of galaxies. This concept is particularly suited for upcoming/on-going large imaging surveys, in which only several broad-band filters are available and it is hard to break some of the degeneracies in the multi-color space. We construct model templates of galaxies using a stellar population synthesis code and apply Bayesian priors on physical properties such as stellar mass and star formation rate. These priors are a function of redshift and they effectively evolve the templates with time in an observationally motivated way. We demonstrate that the priors help reduce the degeneracy and deliver significantly improved photometric redshifts. Furthermore, we show that a template error function, which corrects for systematic flux errors in the model templates as a function of rest-frame wavelength, delivers further improvements. One great advantage of our technique is that we simultaneously measure redshifts...

  15. Spectroscopic confirmation of a galaxy at redshift z = 8.6.

    Science.gov (United States)

    Lehnert, M D; Nesvadba, N P H; Cuby, J-G; Swinbank, A M; Morris, S; Clément, B; Evans, C J; Bremer, M N; Basa, S

    2010-10-21

    Galaxies had their most significant impact on the Universe when they assembled their first generations of stars. Energetic photons emitted by young, massive stars in primeval galaxies ionized the intergalactic medium surrounding their host galaxies, cleared sightlines along which the light of the young galaxies could escape, and fundamentally altered the physical state of the intergalactic gas in the Universe continuously until the present day. Observations of the cosmic microwave background, and of galaxies and quasars at the highest redshifts, suggest that the Universe was reionized through a complex process that was completed about a billion years after the Big Bang, by redshift z ≈ 6. Detecting ionizing Lyman-α photons from increasingly distant galaxies places important constraints on the timing, location and nature of the sources responsible for reionization. Here we report the detection of Lyα photons emitted less than 600 million years after the Big Bang. UDFy-38135539 (ref. 5) is at a redshift of z = 8.5549 ± 0.0002, which is greater than those of the previously known most distant objects, at z = 8.2 (refs 6 and 7) and z = 6.96 (ref. 8). We find that this single source is unlikely to provide enough photons to ionize the volume necessary for the emission line to escape, requiring a significant contribution from other, probably fainter galaxies nearby.

  16. Data augmentation for machine learning redshifts applied to SDSS galaxies

    CERN Document Server

    Hoyle, Ben; Bonnett, Christopher; Seitz, Stella; Weller, Jochen

    2015-01-01

    We present analyses of data augmentation for machine learning redshift estimation. Data augmentation makes a training sample more closely resemble a test sample, if the two base samples differ, in order to improve measured statistics of the test sample. We perform two sets of analyses by selecting 800k (1.7M) SDSS DR8 (DR10) galaxies with spectroscopic redshifts. We construct a base training set by imposing an artificial r band apparent magnitude cut to select only bright galaxies and then augment this base training set by using simulations and by applying the K-correct package to artificially place training set galaxies at a higher redshift. We obtain redshift estimates for the remaining faint galaxy sample, which are not used during training. We find that data augmentation reduces the error on the recovered redshifts by 40% in both sets of analyses, when compared to the difference in error between the ideal case and the non augmented case. The outlier fraction is also reduced by at least 10% and up to 80% u...

  17. Constraining the Redshift Evolution of FIRST Radio Sources in RCS1 Galaxy Clusters

    CERN Document Server

    Gralla, Megan B; Yee, H K C; Barrientos, L Felipe

    2010-01-01

    We conduct a statistical analysis of the radio source population in galaxy clusters as a function of redshift by matching radio sources from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) catalog with 618 optically-selected galaxy clusters from the first Red-Sequence Cluster Survey (RCS1). The number of excess radio sources (above the background level) per cluster is 0.14 +/- 0.02 for clusters with 0.35 1.5 sigma) in the number of radio sources per unit of cluster mass for the galaxy clusters with 0.35 4.1 X 10^(24) W/Hz) radio sources per unit (10^14 solar masses) mass, which we measure to be 0.031 +/- 0.004. We further characterize the population of galaxy cluster-related radio sources through visual inspection of the RCS1 images, finding that although the radio activity of brightest cluster galaxies (BCGs) also does not strongly evolve between our high and low redshift samples, the lower-redshift, richest clusters are more likely to host radio-loud BCGs than the higher-redshift, rich est...

  18. Imaging of Three Possible Low Redshift Analogs to High Redshift Compact Red Galaxies

    CERN Document Server

    Shih, Hsin-Yi

    2011-01-01

    As part of a larger program to identify and characterize possible low-redshift analogs to massive compact red galaxies found at high redshift, we have examined the morphologies of three low-redshift compact galaxies drawn from the sample of Trujillo et al. (2009). Using deeper and higher resolution images, we have found faint and relatively extensive outer structures in addition to the compact cores identified in the earlier measurements. One object appears to have a small companion that may be involved in an ongoing minor merger of the sort that could be responsible for building up the outer parts of these galaxies. The ages of the dominant stellar populations in these objects are found to be around 2--4 Gyr, in good agreement with the previous estimates. The presence of diffuse outer structures in these galaxies indicates that truly compact and massive red galaxies are exceedingly rare at low redshift. The relatively young stellar populations suggest that the accretion of the extensive outer material must o...

  19. Feature importance for machine learning redshifts applied to SDSS galaxies

    CERN Document Server

    Hoyle, Ben; Zitlau, Roman; Steiz, Stella; Weller, Jochen

    2014-01-01

    We present an analysis of importance feature selection applied to photometric redshift estimation using the machine learning architecture Random Decision Forests (RDF) with the ensemble learning routine Adaboost. We select a list of 85 easily measured (or derived) photometric quantities (or 'features') and spectroscopic redshifts for almost two million galaxies from the Sloan Digital Sky Survey Data Release 10. After identifying which features have the most predictive power, we use standard artificial Neural Networks (aNN) to show that the addition of these features, in combination with the standard magnitudes and colours, improves the machine learning redshift estimate by 18% and decreases the catastrophic outlier rate by 32%. We further compare the redshift estimate from RDF using the ensemble learning routine Adaboost with those from two different aNNs, and with photometric redshifts available from the SDSS. We find that the RDF requires orders of magnitude less computation time than the aNNs to obtain a m...

  20. How Accurately Can We Measure Galaxy Environment at High Redshift Using Only Photometric Redshifts?

    Science.gov (United States)

    Florez, Jonathan; Jogee, Shardha; Sherman, Sydney; Papovich, Casey J.; Finkelstein, Steven L.; Stevans, Matthew L.; Kawinwanichakij, Lalitwadee; Ciardullo, Robin; Gronwall, Caryl; SHELA/HETDEX

    2017-06-01

    We use a powerful synergy of six deep photometric surveys (Herschel SPIRE, Spitzer IRAC, NEWFIRM K-band, DECam ugriz, and XMM X-ray) and a future optical spectroscopic survey (HETDEX) in the Stripe 82 field to study galaxy evolution during the 1.9 nearest neighbor densities, and galaxy counts within some projected aperture) at different photometric redshifts to cosmological simulations in order to quantify the uncertainty in our estimates of environment. We also explore how robustly one can recover the variation of galaxy properties with environment, when using only photometric redshifts. In the era of large photometric surveys, this work has broad implications for studies addressing the impact of environment on galaxy evolution at early cosmic epochs. We acknowledge support from NSF grants AST-1614798, AST-1413652 and NSF GRFP grant DGE-1610403.

  1. The rotation curves of galaxies at intermediate redshift

    CERN Document Server

    Vogt, N P; Haynes, M P; Courteau, S; Vogt, Nicole P; Herter, Terry; Haynes, Martha P; Courteau, Stephane

    1996-01-01

    We have undertaken a pilot project to measure the rotation velocities of spiral galaxies in the redshift range 0.18 < z < 0.4 using high dispersion long slit spectroscopy obtained with the Palomar 5m telescope. One field galaxy and three cluster objects known to have strong emission lines were observed over wavelength ranges covering the redshifted lines of [OII], CaII K, H beta, and [OIII]. Two of the objects show extended line emission that allows the tracing of the rotation curve in one or more lines. A line width similar to that obtained with single dish telescopes for the 21-cm HI line observed in lower redshift galaxies can be derived from the observed H beta, [OII], and [OIII] emission by measuring a characteristic width from the velocity histogram. These moderately distant galaxies have much stronger emission lines than typical low-redshift spirals but they appear to be kinematically similar. Application of the Tully-Fisher relation suggests that the two galaxies with rotation curves are intrins...

  2. Stellar Populations and Galaxy Morphology at High Redshift

    CERN Document Server

    Bunker, A J; Stern, D; Thompson, R; Moustakas, L; Davis, M; Dey, A; Bunker, Andrew; Spinrad, Hyron; Stern, Daniel; Thompson, Rodger; Moustakas, Leonidas; Davis, Marc; Dey, Arjun

    2000-01-01

    In this article we investigate the morphology and stellar populations of high-redshift galaxies through multi-waveband HST imaging and ground-based spatially-resolved spectroscopy. We study the redshift evolution of galaxy morphology in the Hubble Deep Field, using the deep IDT-NICMOS near-infrared HST imaging coupled with spectroscopic and photometric redshifts. Using the multi-waveband data to compare the appearance of galaxies at the same rest-frame wavelengths reveals that "morphological k-corrections" (the change in appearance when viewing high-z objects at shorter rest-frame wavelengths) are only important in a minority of cases, and that galaxies were intrinsically more peculiar at high redshift. One example of significant morphological k-corrections is spiral galaxies, which often show more pronounced barred structure in the near-infrared than in the optical. Therefore, the apparent decline in the fraction of barred spirals at faint magnitudes in the optical HDF may be due to band-shifting effects at ...

  3. The redshift distribution of submillimeter galaxies at different wavelengths

    CERN Document Server

    Zavala, J A; Hughes, D H

    2014-01-01

    Using simulations we demonstrate that some of the published redshift distributions of Submillimeter Galaxies (SMGs) at different wavelengths, that were previously reported to be statistically different, are consistent with a parent distribution of the same population of galaxies. The redshift distributions which peak at z_med=2.9, 2.6, 2.2, 2.2, and 2.0 for galaxies selected at 2 and 1.1 mm, and 870, 850, and 450 um respectively, can be derived from a single parent redshift distribution, in contrast with previous studies. The differences can be explained through wavelength selection, depth of the surveys, and to a lesser degree, angular resolution. The main differences are attributed to the temperature of the spectral energy distributions, as shorter-wavelength maps select a hotter population of galaxies. Using the same parent distribution and taking into account lensing bias we can also reproduce the redshift distribution of 1.4 mm-selected ultra-bright galaxies, which peaks at z_med=3.4. However, the redshi...

  4. Evolution of Galaxy Luminosity Function Using Photometric Redshifts

    CERN Document Server

    Ramos, B H F; Benoist, C; da Costa, L N; Maia, M A G; Makler, M; Ogando, R L C; de Simoni, F; Mesquita, A A

    2011-01-01

    We examine the impact of using photometric redshifts for studying the evolution of both the global galaxy luminosity function (LF) and that for different galaxy types. To this end we compare LFs obtained using photometric redshifts from the CFHT Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising ~4800 galaxies. We find that for z<2, in the interval of magnitudes considered by this survey, the LFs obtained using photometric and spectroscopic redshifts show a remarkable agreement. This good agreement led us to use all four Deep fields of CFHTLS comprising ~386000 galaxies to compute the LF of the combined fields and estimate directly the error in the parameters based on field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by ~0.7mag from z~1.8 to z~0.3, while the characteristic density phi* increases by a factor of ~4 in the same redshift bin. We use the galaxy classification provided by the templ...

  5. Studying the Role of Mergers in Black Hole - Galaxy Co-evolution via a Morphological Analysis of Redshift 1 Galaxies

    Science.gov (United States)

    Powell, Meredith; Urry, C. Megan

    2016-06-01

    We study the role of mergers in the quenching of star formation in galaxies at the dominant epoch of their evolution, by examining their color-mass distributions for different morphology types. We use HST ACS data from the CANDELS/GOODS North and South fields for galaxies in the redshift range 0.7 < z < 1.3 and use GALFIT to fit them with sersic profiles, enabling us to classify each as bulge-dominated (early type) or disk-dominated (late type). We find that spirals and ellipticals have distinct color-mass distributions, similar to studies at z=0, in that each have quenching modes of differing time scales. The smooth decay to the red sequence for the disky galaxies corresponds to a slow exhaustion of gas, while the lack of elliptical galaxies in the `green valley' indicates a faster quenching time for galaxies that underwent a major merger. We compare the inactive galaxies to the AGN hosts and find that the AGN phase lasts well into the red sequence for both types of host galaxy, spanning the full color space. The results suggest that the AGN trigger mechanism, as well as the significance of AGN feedback, is dependent on the merger history of the host galaxy.

  6. Comparing Dense Galaxy Cluster Redshift Surveys with Weak Lensing Maps

    CERN Document Server

    Hwang, Ho Seong; Diaferio, Antonaldo; Rines, Kenneth J; Zahid, H Jabran

    2014-01-01

    We use dense redshift surveys of nine galaxy clusters at $z\\sim0.2$ to compare the galaxy distribution in each system with the projected matter distribution from weak lensing. By combining 2087 new MMT/Hectospec redshifts and the data in the literature, we construct spectroscopic samples within the region of weak-lensing maps of high (70--89%) and uniform completeness. With these dense redshift surveys, we construct galaxy number density maps using several galaxy subsamples. The shape of the main cluster concentration in the weak-lensing maps is similar to the global morphology of the number density maps based on cluster members alone, mainly dominated by red members. We cross correlate the galaxy number density maps with the weak-lensing maps. The cross correlation signal when we include foreground and background galaxies at 0.5$z_{\\rm cl}$20% for A383, A689 and A750). The fractional excess in the cross correlation signal including foreground and background structures could be a useful proxy for assessing th...

  7. Will kinematic Sunyaev-Zel'dovich measurements enhance the science return from galaxy redshift surveys?

    Science.gov (United States)

    Sugiyama, Naonori S.; Okumura, Teppei; Spergel, David N.

    2017-01-01

    Yes. Future CMB experiments such as Advanced ACTPol and CMB-S4 should achieve measurements with S/N of > 0.1 for the typical host halo of galaxies in redshift surveys. These measurements will provide complementary measurements of the growth rate of large scale structure f and the expansion rate of the Universe H to galaxy clustering measurements. This paper emphasizes that there is significant information in the anisotropy of the relative pairwise kSZ measurements. We expand the relative pairwise kSZ power spectrum in Legendre polynomials and consider up to its octopole. Assuming that the noise in the filtered maps is uncorrelated between the positions of galaxies in the survey, we derive a simple analytic form for the power spectrum covariance of the relative pairwise kSZ temperature in redshift space. While many previous studies have assumed optimistically that the optical depth of the galaxies τT in the survey is known, we marginalize over τT, to compute constraints on the growth rate f and the expansion rate H. For realistic survey parameters, we find that combining kSZ and galaxy redshift survey data reduces the marginalized 1-σ errors on H and f to ~50-70% compared to the galaxy-only analysis.

  8. ALMA redshifts of millimeter-selected galaxies from the SPT survey: The redshift distribution of dusty star-forming galaxies

    CERN Document Server

    Weiss, A; Marrone, D P; Vieira, J D; Aguirre, J E; Aird, K A; Aravena, M; Ashby, M L N; Bayliss, M; Benson, B A; Bethermin, M; Biggs, A D; Bleem, L E; Bock, J J; Bothwell, M; Bradford, C M; Brodwin, M; Carlstrom, J E; Chang, C L; Chapman, S C; Crawford, T M; Crites, A T; de Haan, T; Dobbs, M A; Downes, T P; Fassnacht, C D; George, E M; Gladders, M D; Gonzalez, A H; Greve, T R; Halverson, N W; Hezaveh, Y D; High, F W; Holder, G P; Holzapfel, W L; Hoover, S; Hrubes, J D; Husband, K; Keisler, R; Lee, A T; Leitch, E M; Lueker, M; Luong-Van, D; Malkan, M; McIntyre, V; McMahon, J J; Mehl, J; Menten, K M; Meyer, S S; Murphy, E J; Padin, S; Plagge, T; Reichardt, C L; Rest, A; Rosenman, M; Ruel, J; Ruhl, J E; Schaffer, K K; Shirokoff, E; Spilker, J S; Stalder, B; Staniszewski, Z; Stark, A A; Story, K; Vanderlinde, K; Welikala, N; Williamson, R

    2013-01-01

    Using the Atacama Large Millimeter/submillimeter Array (ALMA), we have conducted a blind redshift survey in the 3 mm atmospheric transmission window for 26 strongly lensd dusty star-forming galaxies (DSFGs) selected with the South Pole Telescope (SPT). The sources were selected to have S_1.4mm>20 mJy and a dust-like spectrum and, to remove low-z sources, not have bright radio (S_843MHz=3.5. This finding is in contrast to the redshift distribution of radio-identified DSFGs, which have a significantly lower mean redshift of =2.3 and for which only 10-15% of the population is expected to be at z>3. We discuss the effect of gravitational lensing on the redshift distribution and compare our measured redshift distribution to that of models in the literature.

  9. EXTREME HOST GALAXY GROWTH IN POWERFUL EARLY-EPOCH RADIO GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, Peter [Kapteyn Astronomical Institute, University of Groningen (Netherlands); Haas, Martin [Astronomisches Institut, Ruhr Universitaet, Bochum (Germany); Leipski, Christian [Max-Planck-Institut fuer Astronomie, Heidelberg (Germany); Wilkes, Belinda, E-mail: pdb@astro.rug.nl [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)

    2012-10-01

    During the first half of the universe's life, a heyday of star formation must have occurred because many massive galaxies are in place after that epoch in cosmic history. Our observations with the revolutionary Herschel Space Observatory reveal vigorous optically obscured star formation in the ultra-massive hosts of many powerful high-redshift 3C quasars and radio galaxies. This symbiotic occurrence of star formation and black hole driven activity is in marked contrast to recent results dealing with Herschel observations of X-ray-selected active galaxies. Three archetypal radio galaxies at redshifts 1.132, 1.575, and 2.474 are presented here, with inferred star formation rates of hundreds of solar masses per year. A series of spectacular coeval active galactic nucleus/starburst events may have formed these ultra-massive galaxies and their massive central black holes during their relatively short lifetimes.

  10. Multiphase Gas in Intermediate Redshift Galaxies

    CERN Document Server

    Churchill, C W; Charlton, J; Januzzi, B; Churchill, Chris; Mellon, Rick; Charlton, Jane

    2000-01-01

    We present 40 quasar absorption line systems at intermediate redshifts (z~1), with focus on one of the most kinematically complex known, as examples of how the unique capabilities of space-based and ground-based facilities can be combined to glean much broader insights into astrophysical systems.

  11. Predicting the High Redshift Galaxy Population for JWST

    Science.gov (United States)

    Flynn, Zoey; Benson, Andrew

    2017-01-01

    The James Webb Space Telescope will be launched in Oct 2018 with the goal of observing galaxies in the redshift range of z = 10 - 15. As redshift increases, the age of the Universe decreases, allowing us to study objects formed only a few hundred million years after the Big Bang. This will provide a valuable opportunity to test and improve current galaxy formation theory by comparing predictions for mass, luminosity, and number density to the observed data. We have made testable predictions with the semi-analytical galaxy formation model Galacticus. The code uses Markov Chain Monte Carlo methods to determine viable sets of model parameters that match current astronomical data. The resulting constrained model was then set to match the specifications of the JWST Ultra Deep Field Imaging Survey. Predictions utilizing up to 100 viable parameter sets were calculated, allowing us to assess the uncertainty in current theoretical expectations. We predict that the planned UDF will be able to observe a significant number of objects past redshift z > 9 but nothing at redshift z > 11. In order to detect these faint objects at redshifts z = 11-15 we need to increase exposure time by at least a factor of 1.66.

  12. The optical afterglow and host galaxy of GRB 000926

    DEFF Research Database (Denmark)

    Fynbo, J.U.; Gorosabel, J.; Dall, T.H.;

    2002-01-01

    In this paper we illustrate with the case of GRB 000926 how Gamma Ray Bursts (GRBs) can be used as cosmological lighthouses to identify and study star forming galaxies at high redshifts. The optical afterglow of the burst was located with optical imaging at the Nordic Optical Telescope 20.7 hours...... after the burst. Rapid follow-up spectroscopy allowed the determination of the redshift of the burst and a measurement of the host galaxy HI-column density in front of the burst. With late-time narrow band Lyalpha as well as broad band imaging, we have studied the emission from the host galaxy and found...... that it is a strong Lyalpha emitter in a state of active star formation....

  13. High Redshift Galaxies in the Hubble Ultra Deep Field

    CERN Document Server

    Hathi, Nimish P

    2008-01-01

    My dissertation presents results from three recent investigations in the Hubble Ultra Deep Field (HUDF) focusing on understanding structural and physical properties of high redshift galaxies. Here I summarize results from these studies. This thesis work was conducted at Arizona State University under the guidance of Prof. Rogier Windhorst and Prof. Sangeeta Malhotra.

  14. Modeling The GRB Host Galaxy Mass Distribution: Are GRBs Unbiased Tracers of Star Formation?

    Energy Technology Data Exchange (ETDEWEB)

    Kocevski, Daniel; /KIPAC, Menlo Park; West, Andrew A.; /UC, Berkeley, Astron. Dept. /MIT, MKI; Modjaz, Maryam; /UC, Berkeley, Astron. Dept.

    2009-08-03

    We model the mass distribution of long gamma-ray burst (GRB) host galaxies given recent results suggesting that GRBs occur in low metallicity environments. By utilizing measurements of the redshift evolution of the mass-metallicity (M-Z) relationship for galaxies, along with a sharp host metallicity cut-off suggested by Modjaz and collaborators, we estimate an upper limit on the stellar mass of a galaxy that can efficiently produce a GRB as a function of redshift. By employing consistent abundance indicators, we find that sub-solar metallicity cut-offs effectively limit GRBs to low stellar mass spirals and dwarf galaxies at low redshift. At higher redshifts, as the average metallicity of galaxies in the Universe falls, the mass range of galaxies capable of hosting a GRB broadens, with an upper bound approaching the mass of even the largest spiral galaxies. We compare these predicted limits to the growing number of published GRB host masses and find that extremely low metallicity cut-offs of 0.1 to 0.5 Z{sub {circle_dot}} are effectively ruled out by a large number of intermediate mass galaxies at low redshift. A mass function that includes a smooth decrease in the efficiency of producing GRBs in galaxies of metallicity above 12+log(O/H){sub KK04} = 8.7 can, however, accommodate a majority of the measured host galaxy masses. We find that at z {approx} 1, the peak in the observed GRB host mass distribution is inconsistent with the expected peak in the mass of galaxies harboring most of the star formation. This suggests that GRBs are metallicity biased tracers of star formation at low and intermediate redshifts, although our model predicts that this bias should disappear at higher redshifts due to the evolving metallicity content of the universe.

  15. Tuning target selection algorithms to improve galaxy redshift estimates

    Science.gov (United States)

    Hoyle, Ben; Paech, Kerstin; Rau, Markus Michael; Seitz, Stella; Weller, Jochen

    2016-06-01

    We showcase machine learning (ML) inspired target selection algorithms to determine which of all potential targets should be selected first for spectroscopic follow-up. Efficient target selection can improve the ML redshift uncertainties as calculated on an independent sample, while requiring less targets to be observed. We compare seven different ML targeting algorithms with the Sloan Digital Sky Survey (SDSS) target order, and with a random targeting algorithm. The ML inspired algorithms are constructed iteratively by estimating which of the remaining target galaxies will be most difficult for the ML methods to accurately estimate redshifts using the previously observed data. This is performed by predicting the expected redshift error and redshift offset (or bias) of all of the remaining target galaxies. We find that the predicted values of bias and error are accurate to better than 10-30 per cent of the true values, even with only limited training sample sizes. We construct a hypothetical follow-up survey and find that some of the ML targeting algorithms are able to obtain the same redshift predictive power with 2-3 times less observing time, as compared to that of the SDSS, or random, target selection algorithms. The reduction in the required follow-up resources could allow for a change to the follow-up strategy, for example by obtaining deeper spectroscopy, which could improve ML redshift estimates for deeper test data.

  16. UV Properties and Evolution of High-redshift Galaxies

    Science.gov (United States)

    Buzzoni, Alberto

    I assess the problem of morphological and photometric evolution of high-redshift galaxies in the ultraviolet wavelength range. My discussion will partly rely on a new set of template galaxy models, in order to infer the expected changes along the Hubble morphological sequence at the different cosmic epochs. The impact of evolution on the faint-end galaxy luminosity function at z~1 and beyond will also be evaluated and briefly discussed. See http://www.merate.mi.astro.it/~eps/home.html for more info and model retrieval.

  17. UV properties and evolution of high-redshift galaxies

    OpenAIRE

    Buzzoni, Alberto

    2002-01-01

    I assess the problem of morphological and photometric evolution of high-redshift galaxies in the ultraviolet wavelength range. My discussion will partly rely on a new set of template galaxy models, in order to infer the expected changes along the Hubble morphological sequence at the different cosmic epochs. The impact of evolution on the faint-end galaxy luminosity function at z~1 and beyond will also be evaluated and briefly discussed. See http://www.merate.mi.astro.it/~eps/home.html for mor...

  18. UV properties and evolution of high-redshift galaxies

    CERN Document Server

    Buzzoni, A

    2002-01-01

    I assess the problem of morphological and photometric evolution of high-redshift galaxies in the ultraviolet wavelength range. My discussion will partly rely on a new set of template galaxy models, in order to infer the expected changes along the Hubble morphological sequence at the different cosmic epochs. The impact of evolution on the faint-end galaxy luminosity function at z~1 and beyond will also be evaluated and briefly discussed. See http://www.merate.mi.astro.it/~eps/home.html for more info and model retrieval.

  19. Jellyfish Galaxy Candidates at Low Redshift

    Science.gov (United States)

    Poggianti, B. M.; Fasano, G.; Omizzolo, A.; Gullieuszik, M.; Bettoni, D.; Moretti, A.; Paccagnella, A.; Jaffé, Y. L.; Vulcani, B.; Fritz, J.; Couch, W.; D'Onofrio, M.

    2016-03-01

    Galaxies that are being stripped of their gas can sometimes be recognized from their optical appearance. Extreme examples of stripped galaxies are the so-called “jellyfish galaxies” that exhibit tentacles of debris material with a characteristic jellyfish morphology. We have conducted the first systematic search for galaxies that are being stripped of their gas at low-z (z = 0.04-0.07) in different environments, selecting galaxies with varying degrees of morphological evidence for stripping. We have visually inspected B- and V-band images and identified 344 candidates in 71 galaxy clusters of the OMEGAWINGS+WINGS sample and 75 candidates in groups and lower mass structures in the PM2GC sample. We present the atlas of stripping candidates and a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion σ or X-ray luminosity LX. Interestingly, convincing cases of candidates are also found in groups and lower mass halos (1011-1014M⊙), although the physical mechanism at work needs to be securely identified. All the candidates are disky, have stellar masses ranging from log M/M⊙ 11.5 and the majority of them form stars at a rate that is on average a factor of 2 higher (2.5σ) compared to non-stripped galaxies of similar mass. The few post-starburst and passive candidates have weak stripping evidence. We conclude that disturbed morphologies suggestive of stripping phenomena are ubiquitous in clusters and could be present even in groups and low mass halos. Further studies will reveal the physics of the gas stripping and clarify the mechanisms at work.

  20. JELLYFISH GALAXY CANDIDATES AT LOW REDSHIFT

    Energy Technology Data Exchange (ETDEWEB)

    Poggianti, B. M.; Fasano, G.; Omizzolo, A.; Gullieuszik, M.; Bettoni, D.; Paccagnella, A. [INAF-Astronomical Observatory of Padova (Italy); Moretti, A.; D’Onofrio, M. [Physics and Astronomy Department, University of Padova (Italy); Jaffé, Y. L. [Department of Astronomy, Universidad de Concepción, Concepción (Chile); Vulcani, B. [Kavli Institute for the Physics and Mathematics of the universe (WPI), The University of Tokyo Institutes for Advanced Study (UTIAS), the University of Tokyo, Kashiwa, 277-8582 (Japan); Fritz, J. [Centro de Radioastronomía y Astrofísica, CRyA, UNAM, Michoacán (Mexico); Couch, W. [Australian Astronomical Observatory, North Ryde, NSW 1670 (Australia)

    2016-03-15

    Galaxies that are being stripped of their gas can sometimes be recognized from their optical appearance. Extreme examples of stripped galaxies are the so-called “jellyfish galaxies” that exhibit tentacles of debris material with a characteristic jellyfish morphology. We have conducted the first systematic search for galaxies that are being stripped of their gas at low-z (z = 0.04−0.07) in different environments, selecting galaxies with varying degrees of morphological evidence for stripping. We have visually inspected B- and V-band images and identified 344 candidates in 71 galaxy clusters of the OMEGAWINGS+WINGS sample and 75 candidates in groups and lower mass structures in the PM2GC sample. We present the atlas of stripping candidates and a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion σ or X-ray luminosity L{sub X}. Interestingly, convincing cases of candidates are also found in groups and lower mass halos (10{sup 11}−10{sup 14}M{sub ⊙}), although the physical mechanism at work needs to be securely identified. All the candidates are disky, have stellar masses ranging from log M/M{sub ⊙} < 9 to > 11.5 and the majority of them form stars at a rate that is on average a factor of 2 higher (2.5σ) compared to non-stripped galaxies of similar mass. The few post-starburst and passive candidates have weak stripping evidence. We conclude that disturbed morphologies suggestive of stripping phenomena are ubiquitous in clusters and could be present even in groups and low mass halos. Further studies will reveal the physics of the gas stripping and clarify the mechanisms at work.

  1. Stellar Population Maps of High-Redshift Galaxies

    Science.gov (United States)

    Fetherolf, Tara; Reddy, Naveen; MOSDEF

    2016-06-01

    A comprehensive study of resolved galaxy structure can shed light on the formation and evolution of galactic properties, such as the distribution of stars and interstellar dust that obscures starlight. This requires high-resolution, multi-waveband photometry and spectroscopy to completely characterize the galaxies. Previous studies lacked key spectroscopic information, were comprised of small samples, or focused on the local universe. We use HST ACS/WFC3 high-resolution, multi-waveband imaging from the CANDELS project in parallel with moderate-resolution Keck I MOSFIRE spectra from the MOSFIRE Deep Evolution Field (MOSDEF) survey to produce resolved stellar population and dust maps of ~500 galaxies at redshifts 1.4 < z < 2.6—covering the key epoch when galaxies accreted most of their mass. For data preparation and analysis we develop an automated Python program to process our large, comprehensive dataset. From the multi-waveband imaging and spectroscopic redshifts, we model the spectral energy distribution for every resolution element within each galaxy and compare these results to the spectroscopically measured global properties. From our stellar population and dust maps we identify resolved structures within these galaxies. We also investigate if spectroscopically measured galaxy properties are biased when compared with that of localized sub-galactic structures.

  2. Gravitational redshift of galaxies in clusters from SDSS and BOSS

    CERN Document Server

    Sadeh, Iftach; Lahav, Ofer

    2014-01-01

    The gravitational redshift effect allows one to directly probe the gravitational potential in clusters of galaxies. As such, it provides a fundamental test of general relativity (GR), and may help to constrain alternative theories of gravity. Following up on Wojtak, Hansen & Hjorth (2011), we present a new measurement. We take advantage of new data from the tenth data release of SDSS and BOSS, covering a range of redshift between 0.05 and 0.6. After selection, our dataset includes 60k galaxies, matched to 12k clusters, with an average cluster mass of $10^{14} M_{\\odot}$. The analysis is focused on optimizing the selection method of clusters and of galaxies, taking into account possible systematic biases. We compare the light originating from the brightest cluster galaxies (BCGs), to that of galaxies at the outskirts of clusters. We find that BCGs have an average relative redshift of 11 km/s, with a standard deviation of +7 and -5 km/s. The result is consistent with the measurement of Wojtak et al. and is ...

  3. Bulge growth through disk instabilities in high-redshift galaxies

    CERN Document Server

    Bournaud, Frederic

    2015-01-01

    The role of disk instabilities, such as bars and spiral arms, and the associated resonances, in growing bulges in the inner regions of disk galaxies have long been studied in the low-redshift nearby Universe. There it has long been probed observationally, in particular through peanut-shaped bulges. This secular growth of bulges in modern disk galaxies is driven by weak, non-axisymmetric instabilities: it mostly produces pseudo-bulges at slow rates and with long star-formation timescales. Disk instabilities at high redshift (z>1) in moderate-mass to massive galaxies (10^10 to a few 10^11 Msun of stars) are very different from those found in modern spiral galaxies. High-redshift disks are globally unstable and fragment into giant clumps containing 10^8-10^9 Msun of gas and stars each, which results in highly irregular galaxy morphologies. The clumps and other features associated to the violent instability drive disk evolution and bulge growth through various mechanisms, on short timescales. The giant clumps can...

  4. Reconstructing the galaxy density field with photometric redshifts: I. Methodology and validation on stellar mass functions

    CERN Document Server

    Malavasi, Nicola; Cucciati, Olga; Bardelli, Sandro; Cimatti, Andrea

    2016-01-01

    Measuring environment for large numbers of distant galaxies is still an open problem, for which we need galaxy positions and redshifts. Photometric redshifts are more easily available for large numbers of galaxies, but at the price of larger uncertainties than spectroscopic ones. In this work we study how photometric redshifts affect the measurement of galaxy environment and how this may limit an analysis of the galaxy stellar mass function (GSMF) in different environments. Using mock galaxy catalogues, we measured the environment with a fixed aperture method, using each galaxy's true and photometric redshifts. We varied the fixed aperture volume parameters and the photometric redshift uncertainties. We then computed GSMF as a function of redshift and environment. We found that only when using high-precision photometric redshifts with $\\sigma_{\\Delta z/(1+z)} \\le 0.01$, the most extreme environments can be reconstructed in a fairly accurate way, with a fraction $\\ge 60\\div 80\\%$ of galaxies placed in the corr...

  5. Spectroscopic redshifts of galaxies within the Frontier Fields

    CERN Document Server

    Ebeling, H; Barrett, E

    2014-01-01

    We present a catalog of 1848 spectroscopic redshifts measured in the fields of the massive galaxy clusters MACSJ0416.1-2403 ($z=0.397$), MACSJ0717.5+3745 ($z=0.546$), and MACSJ1149.5+2223 ($z=0.544$), i.e., three of the four clusters selected by STScI as the targets of the Frontier Fields (FF) initiative for studies of the distant Universe via gravitational lensing. Compiled in the course of the MACS project (Massive Cluster Survey) that detected the FF clusters, this catalog is provided to the community for three purposes: (1) to allow the identification of cluster members for studies of the galaxy population of these extreme systems, (2) to facilitate the removal of unlensed galaxies and thus reduce shear dilution in weak-lensing analyses, and (3) to improve the calibration of photometric redshifts based on both ground- and spacebased observations of the FF clusters.

  6. CLUSTERING AND PROPERTIES OF GALAXIES AROUND HIGH REDSHIFT RADIO SOURCES

    Directory of Open Access Journals (Sweden)

    C. G. Bornancini

    2009-01-01

    Full Text Available We present measurements of the clustering properties of galaxies in the eld 0:5 < z < 1:5 Ultra Steep Spectrum (USS radio sources selected from SUMSS and NVSS surveys. We nd a comoving correlation length of r0 = 14:0+.- 2:8 h-1 Mpc. We compare our ndings with those obtained in a cosmological N-body simulation populated with GALFORM semi-analytic galaxies. We nd that clusters of galaxies with masses in the range M = 1013:4-14:2 h-1 M have a cluster-galaxy cross-correlation amplitude comparable to those found between USS hosts and galaxies. These results suggest that distant radio galaxies are excellent tracers of galaxy overdensities and pinpoint the progenitors of present day rich clusters of galaxies.

  7. An Empirical Model for the Galaxy Luminosity and Star-Formation Rate Function at High Redshift

    CERN Document Server

    Mashian, Natalie; Loeb, Abraham

    2015-01-01

    Using the most recent measurements of the ultraviolet (UV) luminosity functions (LFs) and dust estimates of early galaxies, we derive updated dust-corrected star-formation rate functions (SFRFs) at z~4-8, which we model to predict the evolution to higher redshifts, z>8. We employ abundance matching techniques to calibrate a relation between galaxy star formation rate (SFR) and host halo mass M{_h} by mapping the shape of the observed SFRFs at z~4-8 to that of the halo mass function. The resulting scaling law remains roughly constant over this redshift range. We apply the average SFR-M{_h} relation to reproduce the observed SFR functions at 4 10 indicate that JWST will be able to detect galaxies out to z~15 with an extensive treasury sized program. We also derive the redshift evolution of the star formation rate density and associated reionization history by galaxies for which we find that the inclusion of galaxies with SFRs well below the current detection limit leads to a fully reionized universe by z~6.5 an...

  8. The host galaxies of AGN with powerful relativistic jets

    Science.gov (United States)

    Olguín-Iglesias, A.; León-Tavares, J.; Kotilainen, J. K.; Chavushyan, V.; Tornikoski, M.; Valtaoja, E.; Añorve, C.; Valdés, J.; Carrasco, L.

    2016-08-01

    We present deep Near-infrared (NIR) images of a sample of 19 intermediate-redshift (0.310^27 WHz^-1), previously classified as flat-spectrum radio quasars. We also compile host galaxy and nuclear magnitudes for blazars from literature. The combined sample (this work and compilation) contains 100 radio-loud AGN with host galaxy detections and a broad range of radio luminosities L1.4GHz = 10^23.7 - 10^28.3WHz^-1, allowing us to divide our sample into high-excitation (quasar-mode; HERGs) and low-excitation (radio-mode; LERGs) radio galaxies. The host galaxies of our sample are bright and seem to follow the Kormendy relation. Nuclear emission (dominated by non-thermal mechanisms) and host-galaxy magnitudes show a slightly negative weak trend for LERGs. On the other hand, the m_bulge -m_nuc relation is statistically significant for HERGs. Although it may be affected by selection effects, this correlation suggests a close coupling between the relativistic jets and their host galaxy. Our findings are consistent with the excitation state (LERG/HERG) scenario. In this view, LERGs emit the bulk of their energy in the form of radio jets, producing a strong feedback mechanism, and HERGs are affected by galaxy mergers and interactions, which provide a common supply of cold gas to feed both nuclear activity and star formation episodes.

  9. The Galaxy Population of Low-Redshift Abell Clusters

    CERN Document Server

    Barkhouse, Wayne A; Lopez-Cruz, Omar

    2009-01-01

    We present a study of the luminosity and color properties of galaxies selected from a sample of 57 low-redshift Abell clusters. We utilize the non-parametric dwarf-to-giant ratio (DGR) and the blue galaxy fraction (fb) to investigate the clustercentric radial-dependent changes in the cluster galaxy population. Composite cluster samples are combined by scaling the counting radius by r200 to minimize radius selection bias. The separation of galaxies into a red and blue population was achieved by selecting galaxies relative to the cluster color-magnitude relation. The DGR of the red and blue galaxies is found to be independent of cluster richness (Bgc), although the DGR is larger for the blue population at all measured radii. A decrease in the DGR for the red and red+blue galaxies is detected in the cluster core region, while the blue galaxy DGR is nearly independent of radius. The fb is found not to correlate with Bgc; however, a steady decline toward the inner-cluster region is observed for the giant galaxies....

  10. WIDESPREAD AND HIDDEN ACTIVE GALACTIC NUCLEI IN STAR-FORMING GALAXIES AT REDSHIFT >0.3

    Energy Technology Data Exchange (ETDEWEB)

    Juneau, Stephanie; Bournaud, Frederic; Daddi, Emanuele; Elbaz, David [CEA-Saclay, DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Dickinson, Mark; Kartaltepe, Jeyhan S. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Alexander, David M.; Mullaney, James R. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Magnelli, Benjamin [Max-Planck-Instituet fuer extraterrestrische Physik, Postfach 1312, D-85741 Garching bei Muenchen (Germany); Hwang, Ho Seong; Willner, S. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Coil, Alison L. [Department of Physics, Center for Astrophysics and Space Sciences, University of California, 9500 Gilman Dr., La Jolla, San Diego, CA 92093 (United States); Rosario, David J. [Max-Planck-Instituet fuer extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching bei Muenchen (Germany); Trump, Jonathan R.; Faber, S. M.; Kocevski, Dale D. [University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Weiner, Benjamin J.; Willmer, Christopher N. A. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California-Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Frayer, David T., E-mail: stephanie.juneau@cea.fr [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); and others

    2013-02-20

    We characterize the incidence of active galactic nuclei (AGNs) in 0.3 < z < 1 star-forming galaxies by applying multi-wavelength AGN diagnostics (X-ray, optical, mid-infrared, radio) to a sample of galaxies selected at 70 {mu}m from the Far-Infrared Deep Extragalactic Legacy survey (FIDEL). Given the depth of FIDEL, we detect 'normal' galaxies on the specific star formation rate (sSFR) sequence as well as starbursting systems with elevated sSFR. We find an overall high occurrence of AGN of 37% {+-} 3%, more than twice as high as in previous studies of galaxies with comparable infrared luminosities and redshifts but in good agreement with the AGN fraction of nearby (0.05 < z < 0.1) galaxies of similar infrared luminosities. The more complete census of AGNs comes from using the recently developed Mass-Excitation (MEx) diagnostic diagram. This optical diagnostic is also sensitive to X-ray weak AGNs and X-ray absorbed AGNs, and reveals that absorbed active nuclei reside almost exclusively in infrared-luminous hosts. The fraction of galaxies hosting an AGN appears to be independent of sSFR and remains elevated both on the sSFR sequence and above. In contrast, the fraction of AGNs that are X-ray absorbed increases substantially with increasing sSFR, possibly due to an increased gas fraction and/or gas density in the host galaxies.

  11. Cosmic Lighthouses : Unveiling the nature of high-redshift galaxies

    CERN Document Server

    Dayal, Pratika

    2011-01-01

    We are in the golden age for the search for high-redshift galaxies, made possible by a combination of new instruments and innovative search techniques. One of the major aims of such searches is to constrain the epoch of reionization (EoR), which marks the second major change in the ionization state of the Universe. Understanding the EoR is difficult since whilst it is galaxy evolution which drives reionization, reionization itself influences galaxy evolution through feedback effects. Unraveling the interplay of reionization and galaxy evolution is further complicated by of a lack of understanding of the metal enrichment and dust distribution in high redshift galaxies. To this end, a class of galaxies called Lyman Alpha Emitters (LAEs) have been gaining enormous popularity as probes of all these three processes. In this thesis, we couple state of the art cosmological SPH simulations (GADGET-2) with a physically motivated, self-consistent model for LAEs, so as to be able to understand the importance of the inte...

  12. Comparison of HI and optical redshifts of galaxies - The impact of redshift uncertainties on spectral line stacking

    CERN Document Server

    Maddox, Natasha; Blyth, S -L; Jarvis, M J

    2013-01-01

    Accurate optical redshifts will be critical for spectral co-adding techniques used to extract detections from below the noise level in ongoing and upcoming surveys for HI, which will extend our current understanding of gas reservoirs in galaxies to lower column densities and higher redshifts. We have used existing, high quality optical and radio data from the SDSS and ALFALFA surveys to investigate the relationship between redshifts derived from optical spectroscopy and neutral hydrogen (HI) spectral line observations. We find that the two redshift measurements agree well, with a negligible systematic offset and a small distribution width. Employing simple simulations, we determine how the width of an ideal stacked HI profile depends on these redshift offsets, as well as larger redshift errors more appropriate for high redshift galaxy surveys. The width of the stacked profile is dominated by the width distribution of the input individual profiles when the redshift errors are less than the median width of the ...

  13. ALMA REDSHIFTS OF MILLIMETER-SELECTED GALAXIES FROM THE SPT SURVEY: THE REDSHIFT DISTRIBUTION OF DUSTY STAR-FORMING GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, A. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); De Breuck, C.; Aravena, M.; Biggs, A. D. [European Southern Observatory, Karl-Schwarzschild Strasse, D-85748 Garching bei Muenchen (Germany); Marrone, D. P.; Bothwell, M. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Vieira, J. D.; Bock, J. J. [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Aguirre, J. E. [University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Aird, K. A. [University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ashby, M. L. N.; Bayliss, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Bethermin, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu - CNRS - Universite Paris Diderot, CEA-Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Bradford, C. M. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 3J5 Canada (Canada); and others

    2013-04-10

    Using the Atacama Large Millimeter/submillimeter Array, we have conducted a blind redshift survey in the 3 mm atmospheric transmission window for 26 strongly lensed dusty star-forming galaxies (DSFGs) selected with the South Pole Telescope. The sources were selected to have S{sub 1.4{sub mm}} > 20 mJy and a dust-like spectrum and, to remove low-z sources, not have bright radio (S{sub 843{sub MHz}} < 6 mJy) or far-infrared counterparts (S{sub 100{sub {mu}m}} < 1 Jy, S{sub 60{sub {mu}m}} < 200 mJy). We robustly detect 44 line features in our survey, which we identify as redshifted emission lines of {sup 12}CO, {sup 13}CO, C I, H{sub 2}O, and H{sub 2}O{sup +}. We find one or more spectral features in 23 sources yielding a {approx}90% detection rate for this survey; in 12 of these sources we detect multiple lines, while in 11 sources we detect only a single line. For the sources with only one detected line, we break the redshift degeneracy with additional spectroscopic observations if available, or infer the most likely line identification based on photometric data. This yields secure redshifts for {approx}70% of the sample. The three sources with no lines detected are tentatively placed in the redshift desert between 1.7 < z < 2.0. The resulting mean redshift of our sample is z-bar = 3.5. This finding is in contrast to the redshift distribution of radio-identified DSFGs, which have a significantly lower mean redshift of z-bar = 2.3 and for which only 10%-15% of the population is expected to be at z > 3. We discuss the effect of gravitational lensing on the redshift distribution and compare our measured redshift distribution to that of models in the literature.

  14. Protoclusters Traced by High-Redshift Massive Galaxies

    Science.gov (United States)

    Garcia-Vergara, C.

    2017-08-01

    A commonly adopted approach to detect protoclusters is to search for overdensities of galaxies around massive galaxies at high-redshift such as quasars (QSOs) and submillimeter galaxies (SMGs). However, the detection of overdensities in those environments has been elusive, against of theoretical predictions. Here, I present the first measurement of the QSO-LBG and QSO-LAE cross-correlation function at z 4, based in the study of 23 QSO fields. My results indicate that LBG are strongly clustered around QSOs but LAE show similar clustering properties and number density as that observed in blank fields. One possible explanation for the lack of overdensities is that galaxies are highly obscured by dust and thus invisible at optical wavelengths. Additionally, I will present the clustering of SMGs based on spectroscopic redshift information of 52 SMGs recently identified by ALMA. This is critical to test if SMGs trace particularly massive structures. Finally, I will discuss the implications and interpretation of my results, in particular, I give the reasons of why I strongly suggest that the study of high-redshift protoclusters should be done from a combined optical+radio perspective.

  15. Clusters of Galaxies at High Redshift

    Science.gov (United States)

    Fort, Bernard

    For a long time, the small number of clusters at z > 0.3 in the Abell survey catalogue and simulations of the standard CDM formation of large scale structures provided a paradigm where clusters were considered as young merging structures. At earlier times, loose concentrations of galaxy clumps were mostly anticipated. Recent observations broke the taboo. Progressively we became convinced that compact and massive clusters at z = 1 or possibly beyond exist and should be searched for.

  16. FIR line emission from high redshift galaxies

    CERN Document Server

    Vallini, Livia; Ferrara, Andrea; Baek, Sunghye

    2013-01-01

    By combining high resolution, radiative transfer cosmological simulations of z~6 galaxies with a sub-grid multi-phase model of their interstellar medium we derive the expected intensity of several far infrared (FIR) emission lines ([C II] 158 micron, [O I] 63 micron, and [N II] 122 micron) for different values of the gas metallicity, Z. For Z = Z_sun the [C II] spectrum is very complex due to the presence of several emitting clumps of individual size < 3 kpc; the peak is displaced from the galaxy center by ~100 km/s. While the [O I] spectrum is also similarly displaced, the [N II] line comes predominantly from the central ionized regions of the galaxy. When integrated over ~500 km/s, the [C II] line flux is 185 mJy km/s; 95% of such flux originates from the cold (T~250 K) H I phase, and only 5% from the warm (T~5000 K) neutral medium. The [O I] and [N II] fluxes are ~6 and ~90 times lower than the [C II] one, respectively. By comparing our results with observations of Himiko, the most extended and luminous...

  17. The Formation of High Redshift Submillimeter Galaxies

    CERN Document Server

    Narayanan, Desika; Cox, Thomas J; Hernquist, Lars; Jonsson, Patrik; Younger, Joshua D; Groves, Brent

    2009-01-01

    We describe a model for the formation of z~2 Submillimeter Galaxies (SMGs) which simultaneously accounts for both average and bright SMGs while providing a reasonable match to their mean observed spectral energy distributions (SEDs). By coupling hydrodynamic simulations of galaxy mergers with the high resolution 3D polychromatic radiative transfer code, Sunrise, we find that a mass sequence of merger models which use observational constraints as physical input naturally yield objects which exhibit black hole, bulge, and H2 gas masses similar to those observed in SMGs. The dominant drivers behind the 850 micron flux are the masses of the merging galaxies and the stellar birthcloud covering fraction. The most luminous (S_850 >~ 15 mJy) sources are recovered by ~10^13 Msun 1:1 major mergers with a birthcloud covering fraction close to unity, whereas more average SMGs (S_850 ~ 5-7 mJy) may be formed in lower mass halos (~5 x 10^12 Msun). These models demonstrate the need for high spatial resolution hydrodynamic a...

  18. Gas Kinematics in GRB Host Galaxies

    DEFF Research Database (Denmark)

    Arabsalmani, Maryam

    The star formation history of the Universe is one of the most complex and interesting chapters in our quest to understand galaxy formation and evolution. Gamma Ray Bursts (GRBs) are beacons of actively star forming galaxies from redshifts near zero back to the cosmic dawn. In addition, they provide...

  19. Gas Kinematics in GRB Host Galaxies

    DEFF Research Database (Denmark)

    Arabsalmani, Maryam

    The star formation history of the Universe is one of the most complex and interesting chapters in our quest to understand galaxy formation and evolution. Gamma Ray Bursts (GRBs) are beacons of actively star forming galaxies from redshifts near zero back to the cosmic dawn. In addition, they provide...

  20. Is there a redshift cutoff for submillimetre galaxies?

    CERN Document Server

    Raymond, G; Dye, S; Carlberg, R; Sullivan, M

    2008-01-01

    We present new optical and infrared photometry for a statistically complete sample of seven 1.1 mm selected sources with accurate Submillimetre Array coordinates. We determine photometric redshifts for four of the seven sources of 4.47, 4.50, 1.49 and 0.64. Of the other three sources two are undetected at optical wavelengths down to the limits of very deep Subaru and Canada-France-Hawaii Telescope images ($\\sim$27 mag AB, i band) and the photometry of the remaining source is corrupted by a bright nearby galaxy. The sources with the highest redshifts are at higher redshifts than all but one of the $\\sim$200 sources taken from the largest recent 850 $\\mu$m surveys, which may indicate that 1.1 mm surveys are more efficient at finding sources at very high redshifts than 850 $\\mu$m surveys. We investigate the evolution of the number density with redshift of our sample using a banded $V_{e}/V_{a}$ analysis and find no evidence for a redshift cutoff, although the number of sources is very small. We also perform the ...

  1. Disk galaxy formation and evolution models up to intermediate redshifts

    CERN Document Server

    Firmani, C

    1999-01-01

    Making use of a seminumerical method we develop a scenario of disk galaxy formation and evolution in the framework of inflationary cold dark matter (CDM) cosmologies. Within the virializing dark matter halos, disks in centrifugal equilibrium are built-up and their galactic evolution is followed through an approach which considers the gravitational interactions among the galaxy components, the turbulence and energy balance of the ISM, the star formation (SF) process due to disk gravitational instabilities, the stellar evolution and the secular formation of a bulge. We find that the main properties and correlations of disk galaxies are determined by the mass, the hierarchical mass aggregation history and the primordial angular momentum. The models follow the same trends across the Hubble sequence than the observed galaxies. The predicted TF relation is in good agreement with the observations except for the standart CDM. While the slope of this relation remains almost constant up to intermediate redshifts, its z...

  2. THE DEEP2 GALAXY REDSHIFT SURVEY: DESIGN, OBSERVATIONS, DATA REDUCTION, AND REDSHIFTS

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Jeffrey A. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California, Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Davis, Marc [Department of Astronomy and Physics, University of California, 601 Campbell Hall, Berkeley, CA 94720 (United States); Faber, S. M.; Guhathakurta, Puragra; Koo, David C.; Phillips, Andrew C.; Conroy, Charlie; Harker, Justin J.; Lai, Kamson [UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Coil, Alison L. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); Dutton, Aaron A. [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Finkbeiner, Douglas P. [Harvard-Smithsonian Center for Astrophysics, Harvard University, 60 Garden St., Cambridge, MA 02138 (United States); Gerke, Brian F. [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., MS 90R4000, Berkeley, CA 94720 (United States); Rosario, David J. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Weiner, Benjamin J.; Willmer, C. N. A. [Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721-0065 (United States); Yan Renbin [Department of Physics and Astronomy, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055 (United States); Kassin, Susan A. [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Konidaris, N. P., E-mail: janewman@pitt.edu, E-mail: djm70@pitt.edu, E-mail: m.cooper@uci.edu, E-mail: mdavis@berkeley.edu, E-mail: faber@ucolick.org, E-mail: koo@ucolick.org, E-mail: raja@ucolick.org, E-mail: phillips@ucolick.org [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); and others

    2013-09-15

    We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z {approx} 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude M{sub B} = -20 at z {approx} 1 via {approx}90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg{sup 2} divided into four separate fields observed to a limiting apparent magnitude of R{sub AB} = 24.1. Objects with z {approx}< 0.7 are readily identifiable using BRI photometry and rejected in three of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted {approx}2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z {approx} 1.45, where the [O II] 3727 A doublet lies in the infrared. The DEIMOS 1200 line mm{sup -1} grating used for the survey delivers high spectral resolution (R {approx} 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or

  3. The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts

    Science.gov (United States)

    Newman, Jeffrey A.; Cooper, Michael C.; Davis, Marc; Faber, S. M.; Coil, Alison L; Guhathakurta, Puraga; Koo, David C.; Phillips, Andrew C.; Conroy, Charlie; Dutton, Aaron A.; Finkbeiner, Douglas P.; Gerke, Brian F.; Rosario, David J.; Weiner, Benjamin J.; Wilmer, C. N. A.; Yan, Renbin; Harker, Justin J.; Kassin, Susan A.; Konidaris, N. P.; Lai, Kamson; Madgwick, Darren S.; Noeske, K. G.; Wirth, Gregory D.; Kirby, Evan N.; Lotz, Jennifer M.

    2013-01-01

    We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z approx. 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude MB = -20 at z approx. 1 via approx.90 nights of observation on the Keck telescope. The survey covers an area of 2.8 Sq. deg divided into four separate fields observed to a limiting apparent magnitude of R(sub AB) = 24.1. Objects with z approx. galaxies with z > 0.7 to be targeted approx. 2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z approx. 1.45, where the [O ii] 3727 Ang. doublet lies in the infrared. The DEIMOS 1200 line mm(exp -1) grating used for the survey delivers high spectral resolution (R approx. 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or other artifacts that in some cases remain after data reduction. Redshift errors and catastrophic failure rates are assessed

  4. Can A Galaxy Redshift Survey Measure Dark Energy Clustering?

    CERN Document Server

    Takada, M

    2006-01-01

    (abridged) A wide-field galaxy redshift survey allows one to probe galaxy clustering at largest spatial scales, which carries an invaluable information on horizon-scale physics complementarily to the cosmic microwave background (CMB). Assuming the planned survey consisting of z~1 and z~3 surveys with areas of 2000 and 300 square degrees, respectively, we study the prospects for probing dark energy clustering from the measured galaxy power spectrum, assuming the dynamical properties of dark energy are specified in terms of the equation of state and the effective sound speed c_e in the context of an adiabatic cold dark matter (CDM) model. The dark energy clustering adds a power to the galaxy power spectrum amplitude at spatial scales greater than the sound horizon, and the enhancement is sensitive to redshift evolution of the net dark energy density, i.e. the equation of state. We find that the galaxy survey, when combined with Planck, can distinguish dark energy clustering from a smooth dark energy model such ...

  5. The SDSS Coadd: A Galaxy Photometric Redshift Catalog

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Ribamar R.R.; /Fermilab /Rio de Janeiro Federal U.; Soares-Santos, Marcelle; /Fermilab /Inst. Geo. Astron., Havana /Sao Paulo U.; Annis, James; /Fermilab; Dodelson, Scott; /Fermilab /Chicago U. /Chicago U., KICP; Hao, Jiangang; /Fermilab; Johnston, David; /Fermilab; Kubo, Jeffrey; /Fermilab; Lin, Huan; /Fermilab; Seo, Hee-Jong; /UC, Berkeley; Simet, Melanie; /Chicago U.

    2011-11-01

    We present and describe a catalog of galaxy photometric redshifts (photo-z's) for the Sloan Digital Sky Survey (SDSS) Coadd Data. We use the Artificial Neural Network (ANN) technique to calculate photo-z's and the Nearest Neighbor Error (NNE) method to estimate photo-z errors for {approx} 13 million objects classified as galaxies in the coadd with r < 24.5. The photo-z and photo-z error estimators are trained and validated on a sample of {approx} 89, 000 galaxies that have SDSS photometry and spectroscopic redshifts measured by the SDSS Data Release 7 (DR7), the Canadian Network for Observational Cosmology Field Galaxy Survey (CNOC2), the Deep Extragalactic Evolutionary Probe Data Release 3(DEEP2 DR3), the SDSS-III's Baryon Oscillation Spectroscopic Survey (BOSS), the Visible imaging Multi-Object Spectrograph - Very Large Telescope Deep Survey (VVDS) and the WiggleZ Dark Energy Survey. For the best ANN methods we have tried, we find that 68% of the galaxies in the validation set have a photo-z error smaller than {sigma}{sub 68} = 0.036. After presenting our results and quality tests, we provide a short guide for users accessing the public data.

  6. Star formation and mass assembly in high redshift galaxies

    CERN Document Server

    Santini, P; Grazian, A; Salimbeni, S; Fiore, F; Fontanot, F; Boutsia, K; Castellano, M; Cristiani, S; De Santis, C; Gallozzi, S; Giallongo, E; Menci, N; Nonino, M; Paris, D; Pentericci, L; Vanzella, E

    2009-01-01

    We study the star formation and the mass assembly process of 0.30.3, the SFR is well correlated with stellar mass, and this relationship seems to steepen with redshift (using IR-based SFRs); b) The contribution to the global SFRD by massive galaxies increases with redshift up to ~2.5, faster than for galaxies of lower mass, but appears to flatten at higher z; c) Despite this increase, the most important contributors to the SFRD at any z are galaxies around, or immediately below, the characteristic stellar mass; d) At z~2, massive galaxies are actively star-forming, with a median SFR 300 Msun/yr. During this epoch, they assemble a substantial part of their final stellar mass; e) The SSFR shows a clear bimodal distribution. The analysis of the SFRD and the SSFR seems to sup port the downsizing scenario, according to which high mass galaxies have formed their stars earlier and faster than their low mass counterparts. A comparison with recent theoretical models shows that they follow the global increase of the SS...

  7. Galaxy bispectrum, primordial non-Gaussianity and redshift space distortions

    Science.gov (United States)

    Tellarini, Matteo; Ross, Ashley J.; Tasinato, Gianmassimo; Wands, David

    2016-06-01

    Measurements of the non-Gaussianity of the primordial density field have the power to considerably improve our understanding of the physics of inflation. Indeed, if we can increase the precision of current measurements by an order of magnitude, a null-detection would rule out many classes of scenarios for generating primordial fluctuations. Large-scale galaxy redshift surveys represent experiments that hold the promise to realise this goal. Thus, we model the galaxy bispectrum and forecast the accuracy with which it will probe the parameter fNL, which represents the degree of primordial local-type non Gaussianity. Specifically, we address the problem of modelling redshift space distortions (RSD) in the tree-level galaxy bispectrum including fNL. We find novel contributions associated with RSD, with the characteristic large scale amplification induced by local-type non-Gaussianity. These RSD effects must be properly accounted for in order to obtain un-biased measurements of fNL from the galaxy bispectrum. We propose an analytic template for the monopole which can be used to fit against data on large scales, extending models used in the recent measurements. Finally, we perform idealised forecasts on σfNL—the accuracy of the determination of local non-linear parameter fNL—from measurements of the galaxy bispectrum. Our findings suggest that current surveys can in principle provide fNL constraints competitive with Planck, and future surveys could improve them further.

  8. Kinematics and Formation Mechanisms of High-Redshift Galaxies

    CERN Document Server

    Law, David R; Ellis, Richard S; Erb, Dawn K; Nesvadba, Nicole; Steidel, Charles C; Swinbank, Mark

    2009-01-01

    Recent years have witnessed a substantial increase in our ability to trace the spatially resolved properties of rapidly star-forming galaxies in the high-redshift universe and numerous studies have suggested the importance of turbulent gas-phase kinematics. In this submission to the Astro 2010 Decadal survey we outline some of the major outstanding questions regarding the kinematics and formation history of these galaxies, such as the prevalence of various kinematic models, the relation to lower surface-brightness populations and faint AGN, and the implications for the evolution of gas accretion and cooling mechanisms with redshift. We comment on the capability of future large optical/IR and millimeter wavelength facilities to address these questions.

  9. Host galaxies of long gamma-ray bursts in the Millennium Simulation

    CERN Document Server

    Chisari, Nora E; Pellizza, Leonardo J

    2010-01-01

    We investigate the nature of the host galaxies of long Gamma-Ray bursts (LGRBs) using a galaxy catalogue constructed from the Millennium Simulation. We developed an LGRB synthetic model based on the hypothesis that LGRBs originate at the end of the life of massive stars following the collapsar model, optionally including a constraint on the metallicity of the progenitor. An observability pipeline was designed to reproduce observations from BATSE experiment and to include a probability estimation for a galaxy to be observationally identified as a host. This new tool allows us to build an observable host galaxy catalogue, required to reproduce the current stellar mass distribution of observed hosts. Systems in our observable catalogue are able to reproduce the observed properties of host galaxies, namely stellar masses, colours, luminosity, star formation activity and metallicities as a function of redshift. At z>2, our model predicts that the observable host galaxies would be very similar to the global galaxy ...

  10. Gravity theories, Transverse Doppler and Gravitational Redshifts in Galaxy Clusters

    CERN Document Server

    Zhao, Hongsheng; Li, Baojiu

    2012-01-01

    There is growing interest in testing alternative gravity theories using the subtle Gravitational Redshifts in clusters of galaxies. However, current models all neglect a Transverse Doppler redshift of similar magnitude, and some models are not self-consistent. An equilibrium model would fix the Gravitational and Transverse Doppler velocity shifts to be about 6\\sigma^2/c and 3\\sigma^2/2c in order to fit the observed velocity dispersion \\sigma self-consistently. This result is from the Virial Theorem for a spherical isotropic cluster, and is insensitive to the theory of gravity. In any case, a gravitational redshift signal cannot directly distinguish between the Einsteinian and f(R) gravity theories, because the mass of the cluster dark halo must be treated as an unknown fitting parameter, whose value must vary according to the theory adopted, otherwise the system would be in equilibrium in one gravity theory and out of equilibrium in another.

  11. EXTENDED PHOTOMETRY FOR THE DEEP2 GALAXY REDSHIFT SURVEY: A TESTBED FOR PHOTOMETRIC REDSHIFT EXPERIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Matthews, Daniel J.; Newman, Jeffrey A. [Department of Physics and Astronomy, University of Pittsburgh, 3941 O' Hara Street, Pittsburgh, PA 15260 (United States); Coil, Alison L. [Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California, Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Gwyn, Stephen D. J., E-mail: djm70@pitt.edu, E-mail: janewman@pitt.edu, E-mail: acoil@ucsd.edu, E-mail: m.cooper@uci.edu, E-mail: Stephen.Gwyn@nrc-cnrc.gc.ca [Canadian Astronomical Data Centre, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7 (Canada)

    2013-02-15

    This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains {approx}27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.

  12. A faint galaxy redshift survey behind massive clusters

    Energy Technology Data Exchange (ETDEWEB)

    Frye, Brenda

    1999-12-01

    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 {approximately}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.

  13. A faint galaxy redshift survey behind massive clusters

    Energy Technology Data Exchange (ETDEWEB)

    Frye, Brenda Louise [Univ. of California, Berkeley, CA (United States)

    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.

  14. VizieR Online Data Catalog: Properties of SN host galaxies (Kelly+, 2014)

    Science.gov (United States)

    Kelly, P. L.; Filippenko, A. V.; Modjaz, M.; Kocevski, D.

    2017-03-01

    We study the host galaxies of both nearby (zsearches (e.g., the Palomar Transient Factory (PTF); Rau et al., 2009PASP..121.1334R; Law et al., 2009PASP..121.1395L), which do not target specific potential hosts or z<1.2 LGRBs detected by gamma-ray satellites. We use the SDSS spectroscopic sample to build a control sample of low-redshift star-forming galaxies and SDSS photometry and spectroscopy to measure properties of both the sample of low-redshift star-forming galaxies and the host galaxies of the nearby SNe. For the host galaxies of z<1.2 LGRBs, we estimate host properties using published photometry and HST imaging. (2 data files).

  15. Cloning Dropouts: Implications for Galaxy Evolution at High Redshift

    CERN Document Server

    Bouwens, R J; Illingworth, G D; Bouwens, Rychard J.; Broadhurst, Tom; Illingworth, Garth

    2003-01-01

    The evolution of high redshift galaxies in the two Hubble Deep Fields, HDF-N and HDF-S, is investigated using a cloning technique that replicates z~ 2-3 U dropouts to higher redshifts, allowing a comparison with the observed B and V dropouts at higher redshifts (z ~ 4-5). We treat each galaxy selected for replication as a set of pixels that are k-corrected to higher redshift, accounting for resampling, shot-noise, surface-brightness dimming, and the cosmological model. We find evidence for size evolution (a 1.7x increase) from z ~ 5 to z ~ 2.7 for flat geometries (Omega_M+Omega_LAMBDA=1.0). Simple scaling laws for this cosmology predict that size evolution goes as (1+z)^{-1}, consistent with our result. The UV luminosity density shows a similar increase (1.85x) from z ~ 5 to z ~ 2.7, with minimal evolution in the distribution of intrinsic colors for the dropout population. In general, these results indicate less evolution than was previously reported, and therefore a higher luminosity density at z ~ 4-5 (~ 50...

  16. Dust Attenuation in High Redshift Galaxies -- 'Diamonds in the Sky'

    CERN Document Server

    Scoville, Nick; Capak, Peter; Kakazu, Yuko; Li, Gongjie; Steinhardt, Charles

    2014-01-01

    We use observed optical to near infrared spectral energy distributions (SEDs) of 266 galaxies in the COSMOS survey to derive the wavelength dependence of the dust attenuation at high redshift. All of the galaxies have spectroscopic redshifts in the range z = 2 to 6.5. The presence of the CIV absorption feature, indicating that the rest-frame UV-optical SED is dominated by OB stars, is used to select objects for which the intrinsic, unattenuated spectrum has a well-established shape. Comparison of this intrinsic spectrum with the observed broadband photometric SED then permits derivation of the wavelength dependence of the dust attenuation. The derived dust attenuation curve is similar in overall shape to the Calzetti curve for local starburst galaxies. We also see the 2175 \\AA~bump feature which is present in the Milky Way and LMC extinction curves but not seen in the Calzetti curve. The bump feature is commonly attributed to graphite or PAHs. No significant dependence is seen with redshift between sub-sample...

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

    Science.gov (United States)

    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.

  18. The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts

    Science.gov (United States)

    Newman, Jeffrey A.; Cooper, Michael C.; Davis, Marc; Faber, S. M.; Coil, Alison L.; Guhathakurta, Puragra; Koo, David C.; Phillips, Andrew C.; Conroy, Charlie; Dutton, Aaron A.; Finkbeiner, Douglas P.; Gerke, Brian F.; Rosario, David J.; Weiner, Benjamin J.; Willmer, C. N. A.; Yan, Renbin; Harker, Justin J.; Kassin, Susan A.; Konidaris, N. P.; Lai, Kamson; Madgwick, Darren S.; Noeske, K. G.; Wirth, Gregory D.; Connolly, A. J.; Kaiser, N.; Kirby, Evan N.; Lemaux, Brian C.; Lin, Lihwai; Lotz, Jennifer M.; Luppino, G. A.; Marinoni, C.; Matthews, Daniel J.; Metevier, Anne; Schiavon, Ricardo P.

    2013-09-01

    We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z ~ 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude MB = -20 at z ~ 1 via ~90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg2 divided into four separate fields observed to a limiting apparent magnitude of R AB = 24.1. Objects with z 0.7 to be targeted ~2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z ~ 1.45, where the [O II] 3727 Å doublet lies in the infrared. The DEIMOS 1200 line mm-1 grating used for the survey delivers high spectral resolution (R ~ 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or other artifacts that in some cases remain after data reduction. Redshift errors and catastrophic failure rates are assessed through more than 2000 objects with duplicate observations. Sky subtraction is

  19. Dark-ages reionization and galaxy formation simulation - IV. UV luminosity functions of high-redshift galaxies

    Science.gov (United States)

    Liu, Chuanwu; Mutch, Simon J.; Angel, P. W.; Duffy, Alan R.; Geil, Paul M.; Poole, Gregory B.; Mesinger, Andrei; Wyithe, J. Stuart B.

    2016-10-01

    In this paper, we present calculations of the UV luminosity function (LF) from the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulations project, which combines N-body, semi-analytic and seminumerical modelling designed to study galaxy formation during the Epoch of Reionization. Using galaxy formation physics including supernova feedback, the model naturally reproduces the UV LFs for high-redshift star-forming galaxies from z ˜ 5 through to z ˜ 10. We investigate the luminosity-star formation rate (SFR) relation, finding that variable SFR histories of galaxies result in a scatter around the median relation of 0.1-0.3 dex depending on UV luminosity. We find close agreement between the model and observationally derived SFR functions. We use our calculated luminosities to investigate the LF below current detection limits, and the ionizing photon budget for reionization. We predict that the slope of the UV LF remains steep below current detection limits and becomes flat at MUV ≳ -14. We find that 48 (17) per cent of the total UV flux at z ˜ 6 (10) has been detected above an observational limit of MUV ˜ -17, and that galaxies fainter than MUV ˜ -17 are the main source of ionizing photons for reionization. We investigate the luminosity-stellar mass relation, and find a correlation for galaxies with MUV luminosity-halo mass relation to be M_vir ∝ 10^{-0.35M_UV}, finding that galaxies with MUV = -20 reside in host dark matter haloes of 1011.0±0.1 M⊙ at z ˜ 6, and that this mass decreases towards high redshift.

  20. High Redshift Radio Galaxies: Laboratories for Massive Galaxy and Cluster Formation in the early Universe

    CERN Document Server

    Miley, G; Taylor, G B; De Breuck, C; Cohen, A

    2009-01-01

    High redshift radio galaxies are among the largest, most luminous, most massive, and most beautiful objects in the Universe. They are generally identified from their radio emission, thought to be powered by accretion of matter onto supermassive black holes in the nuclei of their host galaxies. Observations show that they are energetic sources of radiation throughout most of the electromagnetic spectrum, including relativistic plasma, gas and dust, stars and the active galactic nuclei (AGN). 1 HzRGs are inferred to be extremely massive, including old stars (up to $\\sim$ 10$^{12}$ M$_{\\odot}$), hot gas (up to $\\sim$ 10$^{12}$ M$_{\\odot}$) and molecular gas (up to $\\sim$ 10$^{11}$ M$_{\\odot}$).Because they are highly luminous and (unlike quasars) spatially resolvable from the ground, most components of HzRGs provide important diagnostic information about the spatial distributions of processes within HzRGs and their environment. The fact that the different constituents are present in the same objects and that the...

  1. The ESO Slice Project (ESP) galaxy redshift survey. IV. A discussion of systematic biases in galaxy redshift determinations

    Science.gov (United States)

    Cappi, A.; Zamorani, G.; Zucca, E.; Vettolani, G.; Merighi, R.; Mignoli, M.; Stirpe, G. M.; Collins, C.; Guzzo, L.; Chincarini, G.; Maccagni, D.; Balkowski, C.; Cayatte, V.; Maurogordato, S.; Proust, D.; Bardelli, S.; Ramella, M.; Scaramella, R.; Blanchard, A.; MacGillivray, H.

    1998-08-01

    We present a detailed discussion of the redshift errors associated to the ESO Slice Project measurements. For a subsample of 742 galaxies with redshifts determined both from the absorption lines (Vabs) and from the emission lines (Vemi), we find an average difference Vabs - Vemi> =~ +100 km/s. We find that a similar effect is present in another, deeper redshift survey, the Durham/Anglo-Australian Telescope faint galaxy redshift survey (Broadhurst et al. 1988), while is absent in surveys at brighter magnitude limits. We have investigated in detail many possible sources of such a discrepancy, and we can exclude possible zero-point shifts or calibration problems. We have detected and measured systematic velocity differences produced by the different templates used in the cross-correlation. We conclude that such differences can in principle explain the effect, but in this case the non-trivial implication would be that the best-fitting template does not necessarily give the best velocity estimate. As we do not have any a priori reason to select a template different from the best-fitting one, we did not apply any correction to the ESO Slice Project velocities. However, as for a small number of galaxies the effect is so large that it is likely to have a physical explanation, we have also taken into account the possibility that the discrepancy can be partly real: in this case, it might help to understand the role of gas outflows in the process of galaxy evolution. In view of the future large spectroscopic surveys, we stress the importance of using different templates and making them publicly available, in order to assess the amplitude of systematic effects, and to allow a direct comparison of different catalogues. based on observations collected at the European Southern Observatory, La Silla, Chile.

  2. The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups

    Energy Technology Data Exchange (ETDEWEB)

    Gerke, Brian F.; /UC, Berkeley; Newman, Jeffrey A.; /LBNL, NSD; Davis, Marc; /UC, Berkeley /UC, Berkeley, Astron.Dept.; Marinoni, Christian; /Brera Observ.; Yan, Renbin; Coil, Alison L.; Conroy, Charlie; Cooper, Michael C.; /UC, Berkeley, Astron.Dept.; Faber, S.M.; /Lick Observ.; Finkbeiner, Douglas P.; /Princeton U. Observ.; Guhathakurta, Puragra; /Lick Observ.; Kaiser, Nick; /Hawaii U.; Koo, David C.; Phillips, Andrew C.; /Lick Observ.; Weiner, Benjamin J.; /Maryland U.

    2012-02-14

    We use the first 25% of the DEEP2 Galaxy Redshift Survey spectroscopic data to identify groups and clusters of galaxies in redshift space. The data set contains 8370 galaxies with confirmed redshifts in the range 0.7 {<=} z {<=} 1.4, over one square degree on the sky. Groups are identified using an algorithm (the Voronoi-Delaunay Method) that has been shown to accurately reproduce the statistics of groups in simulated DEEP2-like samples. We optimize this algorithm for the DEEP2 survey by applying it to realistic mock galaxy catalogs and assessing the results using a stringent set of criteria for measuring group-finding success, which we develop and describe in detail here. We find in particular that the group-finder can successfully identify {approx}78% of real groups and that {approx}79% of the galaxies that are true members of groups can be identified as such. Conversely, we estimate that {approx}55% of the groups we find can be definitively identified with real groups and that {approx}46% of the galaxies we place into groups are interloper field galaxies. Most importantly, we find that it is possible to measure the distribution of groups in redshift and velocity dispersion, n({sigma}, z), to an accuracy limited by cosmic variance, for dispersions greater than 350 km s{sup -1}. We anticipate that such measurements will allow strong constraints to be placed on the equation of state of the dark energy in the future. Finally, we present the first DEEP2 group catalog, which assigns 32% of the galaxies to 899 distinct groups with two or more members, 153 of which have velocity dispersions above 350 km s{sup -1}. We provide locations, redshifts and properties for this high-dispersion subsample. This catalog represents the largest sample to date of spectroscopically detected groups at z {approx} 1.

  3. The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups

    Energy Technology Data Exchange (ETDEWEB)

    Gerke, Brian F.; /UC, Berkeley; Newman, Jeffrey A.; /LBNL, NSD; Davis, Marc; /UC, Berkeley /UC, Berkeley, Astron.Dept.; Marinoni, Christian; /Brera Observ.; Yan, Renbin; Coil, Alison L.; Conroy, Charlie; Cooper, Michael C.; /UC, Berkeley, Astron.Dept.; Faber, S.M.; /Lick Observ.; Finkbeiner, Douglas P.; /Princeton U. Observ.; Guhathakurta, Puragra; /Lick Observ.; Kaiser, Nick; /Hawaii U.; Koo, David C.; Phillips, Andrew C.; /Lick Observ.; Weiner, Benjamin J.; /Maryland U.

    2012-02-14

    We use the first 25% of the DEEP2 Galaxy Redshift Survey spectroscopic data to identify groups and clusters of galaxies in redshift space. The data set contains 8370 galaxies with confirmed redshifts in the range 0.7 {<=} z {<=} 1.4, over one square degree on the sky. Groups are identified using an algorithm (the Voronoi-Delaunay Method) that has been shown to accurately reproduce the statistics of groups in simulated DEEP2-like samples. We optimize this algorithm for the DEEP2 survey by applying it to realistic mock galaxy catalogs and assessing the results using a stringent set of criteria for measuring group-finding success, which we develop and describe in detail here. We find in particular that the group-finder can successfully identify {approx}78% of real groups and that {approx}79% of the galaxies that are true members of groups can be identified as such. Conversely, we estimate that {approx}55% of the groups we find can be definitively identified with real groups and that {approx}46% of the galaxies we place into groups are interloper field galaxies. Most importantly, we find that it is possible to measure the distribution of groups in redshift and velocity dispersion, n({sigma}, z), to an accuracy limited by cosmic variance, for dispersions greater than 350 km s{sup -1}. We anticipate that such measurements will allow strong constraints to be placed on the equation of state of the dark energy in the future. Finally, we present the first DEEP2 group catalog, which assigns 32% of the galaxies to 899 distinct groups with two or more members, 153 of which have velocity dispersions above 350 km s{sup -1}. We provide locations, redshifts and properties for this high-dispersion subsample. This catalog represents the largest sample to date of spectroscopically detected groups at z {approx} 1.

  4. Two Moderate-Redshift Analogs to Compact Massive Early-Type Galaxies at High Redshifts

    CERN Document Server

    Stockton, Alan; Larson, Kirsten

    2009-01-01

    From a search of a portion of the sky covered by the SDSS and UKIDSS databases, we have located 2 galaxies at z~0.5 that have properties similar to those of the luminous passive compact galaxies found at z~2.5. From Keck moderate-resolution spectroscopy and laser-guided adaptive-optics imaging of these galaxies, we can begin to put together a more detailed picture of what their high-redshift counterparts might be like. Spectral-synthesis models that fit the u to K photometry also seem to give good fits to the spectral features. From these models, we estimate masses in the range of 3-4 10^11 M_sun for both galaxies. Under the assumption that these are spheroidal galaxies, our velocity dispersions give estimated masses about a factor of 3 smaller. However, our high-resolution imaging data indicate that these galaxies are not normal spheroids, and the interpretation of the kinematic data depends critically on the actual morphologies and the nature of the stellar orbits. While recent suggestions that the populati...

  5. Primordial alignment of elliptical galaxies in intermediate redshift clusters

    CERN Document Server

    Rong, Yu; Liao, Jin-Yuan

    2015-01-01

    We measure primordial alignments for the red galaxies in the sample of eight massive galaxy clusters in the southern sky from the CLASH-VLT Large Programme, at a median redshift of 0.375. We find primordial alignment with about $3\\sigma$ significance in the four dynamically young clusters, but null detection of primordial alignment in the four highly relaxed clusters. The observed primordial alignment is not dominated by any single one of the four dynamically young clusters, and is primarily due to a population of bright galaxies ($M_r<-20.5\\ \\rm{m}$) residing in the region 300 to 810 kpc from the cluster centers. For the first time, we point out that the combination of radial alignment and halo alignment can cause fake primordial alignment. Finally, we find that the detected alignment for the dynamically young clusters is real rather than fake primordial alignment.

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

    CERN Document Server

    Oklopcic, Antonija; Feldmann, Robert; Keres, Dusan; Faucher-Giguere, Claude-Andre; Murray, Norman

    2016-01-01

    The morphology of massive star-forming galaxies at high redshift is often dominated by giant clumps of mass ~10^8-10^9 Msun 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 that implement explicit treatments of stellar feedback and ISM physics to study the properties of these clumps. We follow the evolution of giant clumps in a massive (stellar mass ~10^10.8 Msun 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 ~2...

  7. Dust in the Circumgalactic Medium of Low-Redshift Galaxies

    CERN Document Server

    Peek, J E G; Corrales, Lia

    2014-01-01

    Using spectroscopically selected galaxies from the Sloan Digital Sky Survey we present a detection of reddening due to dust in the circumgalactic medium of galaxies. We detect the mean change in the colors of "standard crayons" correlated with the presence of foreground galaxies at z ~0.05 as a function of angular separation. Following Peek & Graves (2010), we create standard crayons using passively evolving galaxies corrected for Milky Way reddening and color-redshift trends, leading to a sample with as little as 2% scatter in color. We devise methods to ameliorate possible systematic effects related to the estimation of colors, and we find an excess reddening induced by foreground galaxies at a level ranging from 10 to 0.5 millimagnitudes on scales ranging from 30 kpc to 1 Mpc. We attribute this effect to a large-scale distribution of dust around galaxies similar to the findings of Menard et al. 2010. We find that circumgalactic reddening is a weak function of stellar mass over the range $6 \\times 10^9 ...

  8. Rapidly star-forming galaxies adjacent to quasars at redshifts exceeding 6

    Science.gov (United States)

    Decarli, R.; Walter, F.; Venemans, B. P.; Bañados, E.; Bertoldi, F.; Carilli, C.; Fan, X.; Farina, E. P.; Mazzucchelli, C.; Riechers, D.; Rix, H.-W.; Strauss, M. A.; Wang, R.; Yang, Y.

    2017-05-01

    The existence of massive (1011 solar masses) elliptical galaxies by redshift z ≈ 4 (refs 1, 2, 3; when the Universe was 1.5 billion years old) necessitates the presence of galaxies with star-formation rates exceeding 100 solar masses per year at z > 6 (corresponding to an age of the Universe of less than 1 billion years). Surveys have discovered hundreds of galaxies at these early cosmic epochs, but their star-formation rates are more than an order of magnitude lower. The only known galaxies with very high star-formation rates at z > 6 are, with one exception, the host galaxies of quasars, but these galaxies also host accreting supermassive (more than 109 solar masses) black holes, which probably affect the properties of the galaxies. Here we report observations of an emission line of singly ionized carbon ([C II] at a wavelength of 158 micrometres) in four galaxies at z > 6 that are companions of quasars, with velocity offsets of less than 600 kilometres per second and linear offsets of less than 100 kiloparsecs. The discovery of these four galaxies was serendipitous; they are close to their companion quasars and appear bright in the far-infrared. On the basis of the [C II] measurements, we estimate star-formation rates in the companions of more than 100 solar masses per year. These sources are similar to the host galaxies of the quasars in [C II] brightness, linewidth and implied dynamical mass, but do not show evidence for accreting supermassive black holes. Similar systems have previously been found at lower redshift. We find such close companions in four out of the twenty-five z > 6 quasars surveyed, a fraction that needs to be accounted for in simulations. If they are representative of the bright end of the [C II] luminosity function, then they can account for the population of massive elliptical galaxies at z ≈ 4 in terms of the density of cosmic space.

  9. Galaxy sizes as a function of environment at intermediate redshift from the ESO Distant Cluster Survey

    CERN Document Server

    Kelkar, Kshitija; Gray, Meghan E; Maltby, David; Vulcani, Benedetta; De Lucia, Gabriella; Poggianti, Bianca M; Zaritsky, Dennis

    2015-01-01

    In order to assess whether the environment has a significant effect on galaxy sizes, we compare the mass--size relations of cluster and field galaxies in the $0.4 1$), with early-type/passive galaxies in higher density environments growing earlier. Such dependence disappears at lower redshifts. Therefore, if the reported difference at higher-$z$ is real, the growth of field galaxies has caught up with that of cluster galaxies by $z\\sim1$. Any putative mechanism responsible for galaxy growth has to account for the existence of environmental differences at high redshift and their absence (or weakening) at lower redshifts.

  10. How SN Ia host-galaxy properties affect cosmological parameters

    CERN Document Server

    Campbell, H; Gilmore, G

    2016-01-01

    We present a systematic study of the relationship between Type Ia Supernova (SN Ia) properties, and the characteristics of their host galaxies, using a sample of 581 SNe Ia from the full Sloan Digital Sky Survey II (SDSS-II) SN Survey. We also investigate the effects of this on the cosmological constraints derived from SNe~Ia. Compared to previous studies, our sample is larger by a factor of $>4$, and covers a substantially larger redshift range (up to z~0.5), which is directly applicable to the volume of cosmological interest. We measure a significant correlation (>5\\sigma) between the host-galaxy stellar-mass and the SN~Ia Hubble Residuals (HR). We find a weak correlation (1.4\\sigma) between the host-galaxy metallicity as measured from emission lines in the spectra, and the SN~Ia HR. We also find evidence that the slope of the correlation between host-galaxy mass and HR is -0.11 $\\mathrm{mag}/\\mathrm{log}(\\mathrm{M}_{\\mathrm{host}}/\\mathrm{M}_{\\odot})$ steeper in lower metallicity galaxies. We test the effe...

  11. A Morphological Study of Gamma-Ray Burst Host Galaxies

    CERN Document Server

    Wainwright, C; Penprase, B E

    2005-01-01

    We present a comprehensive study of the morphological properties of 42 gamma-ray burst (GRB) host galaxies imaged with the Hubble Space Telescope in the optical band. The purpose of this study is to understand the relation of GRBs to their macro-environments, and to compare the GRB-selected galaxies to other high redshift samples. We perform both qualitative and quantitative analyses by categorizing the galaxies according to their visual properties, and by examining their surface brightness profiles. We find that all of the galaxies have approximately exponential profiles, indicative of galactic disks, and have a median scale length of about 1.7 kpc. Inspection of the visual morphologies reveals a high fraction of merging and interacting systems, with \\~30% showing clear signs of interaction, and an additional ~30% exhibiting irregular and asymmetric structure which may be the result of recent mergers; these fractions are independent of redshift and galaxy luminosity. On the other hand, the three GRB host gal...

  12. The DEEP2 Galaxy Redshift Survey: Color and Luminosity Dependence of Galaxy Clustering at z~1

    CERN Document Server

    Coil, Alison L; Croton, Darren; Cooper, Michael C; Davis, Marc; Faber, S M; Gerke, Brian F; Koo, David C; Padmanabhan, Nikhil; Wechsler, Risa H; Weiner, Benjamin J

    2007-01-01

    We present measurements of the color and luminosity dependence of galaxy clustering at z~1 in the DEEP2 Galaxy Redshift Survey. Using volume-limited subsamples in bins of both color and luminosity, we find that: 1) The clustering dependence is much stronger with color than with luminosity and is as strong with color at z~1 as is found locally. We find no dependence of the clustering amplitude on color for galaxies on the red sequence, but a significant dependence on color for galaxies within the blue cloud. 2) For galaxies in the range L/L*~0.7-2, a stronger large-scale luminosity dependence is seen for all galaxies than for red and blue galaxies separately. The small-scale clustering amplitude depends significantly on luminosity for blue galaxies, with brighter samples having a stronger rise on scales r_p<0.5 Mpc/h. 3) Redder galaxies exhibit stronger small-scale redshift-space distortions ("fingers of god"), and both red and blue populations show large-scale distortions in xi(r_p,pi) due to coherent infa...

  13. The 2dF Galaxy Redshift Survey: stochastic relative biasing between galaxy populations

    CERN Document Server

    Wild, V; Lahav, O; Conway, E; Maddox, S; Baldry, I K; Baugh, C M; Bland-Hawthorn, J; Bridges, T; Cannon, R; Cole, S; Colless, M; Collins, C; Couch, W; Dalton, G B; De Propris, R; Driver, S P; Efstathiou, G P; Ellis, Richard S; Frenk, C S; Glazebrook, K; Jackson, C; Lewis, I; Lumsden, S; Madgwick, D; Norberg, P; Peterson, B A; Sutherland, W; Taylor, K

    2004-01-01

    It is well known that the clustering of galaxies depends on galaxy type. Such relative bias complicates the inference of cosmological parameters from galaxy redshift surveys, and is a challenge to theories of galaxy formation and evolution. In this paper we perform a joint counts-in-cells analysis on galaxies in the 2dF Galaxy Redshift Survey, classified by both colour and spectral type, eta, as early or late type galaxies. We fit three different models of relative bias to the joint probability distribution of the cell counts, assuming Poisson sampling of the galaxy density field. We investigate the nonlinearity and stochasticity of the relative bias, with cubical cells of side 10Mpc \\leq L \\leq 45Mpc (h=0.7). Exact linear bias is ruled out with high significance on all scales. Power law bias gives a better fit, but likelihood ratios prefer a bivariate lognormal distribution, with a non-zero `stochasticity' - i.e. scatter that may result from physical effects on galaxy formation other than those from the loca...

  14. Reconstructing the galaxy redshift distribution from angular cross power spectra

    CERN Document Server

    Sun, L; Tao, C

    2015-01-01

    The control of photometric redshift (photo-$z$) errors is a crucial and challenging task for precision weak lensing cosmology. The spacial cross-correlations (equivalently, the angular cross power spectra) of galaxies between tomographic photo-$z$ bins are sensitive to the true redshift distribution $n_i(z)$ of each bin and hence can help calibrate the photo-$z$ error distribution for weak lensing surveys. Using Fisher matrix analysis, we investigate the contributions of various components of the angular power spectra to the constraints of $n_i(z)$ parameters and demonstrate the importance of the cross power spectra therein, especially when catastrophic photo-$z$ errors are present. We further study the feasibility of reconstructing $n_i(z)$ from galaxy angular power spectra using Markov Chain Monte Carlo estimation. Considering an LSST-like survey with $10$ photo-$z$ bins, we find that the underlying redshift distribution can be determined with a fractional precision ($\\sigma(\\theta)/\\theta$ for parameter $\\...

  15. The host galaxy of a fast radio burst.

    Science.gov (United States)

    Keane, E F; Johnston, S; Bhandari, S; Barr, E; Bhat, N D R; Burgay, M; Caleb, M; Flynn, C; Jameson, A; Kramer, M; Petroff, E; Possenti, A; van Straten, W; Bailes, M; Burke-Spolaor, S; Eatough, R P; Stappers, B W; Totani, T; Honma, M; Furusawa, H; Hattori, T; Morokuma, T; Niino, Y; Sugai, H; Terai, T; Tominaga, N; Yamasaki, S; Yasuda, N; Allen, R; Cooke, J; Jencson, J; Kasliwal, M M; Kaplan, D L; Tingay, S J; Williams, A; Wayth, R; Chandra, P; Perrodin, D; Berezina, M; Mickaliger, M; Bassa, C

    2016-02-25

    In recent years, millisecond-duration radio signals originating in distant galaxies appear to have been discovered in the so-called fast radio bursts. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity, which, in tandem with a redshift measurement, can be used for fundamental physical investigations. Every fast radio burst has a dispersion measurement, but none before now have had a redshift measurement, because of the difficulty in pinpointing their celestial coordinates. Here we report the discovery of a fast radio burst and the identification of a fading radio transient lasting ~6 days after the event, which we use to identify the host galaxy; we measure the galaxy's redshift to be z = 0.492 ± 0.008. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionized baryons in the intergalactic medium of ΩIGM = 4.9 ± 1.3 per cent, in agreement with the expectation from the Wilkinson Microwave Anisotropy Probe, and including all of the so-called 'missing baryons'. The ~6-day radio transient is largely consistent with the radio afterglow of a short γ-ray burst, and its existence and timescale do not support progenitor models such as giant pulses from pulsars, and supernovae. This contrasts with the interpretation of another recently discovered fast radio burst, suggesting that there are at least two classes of bursts.

  16. Optical galaxy cluster detection across a wide redshift range

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Jiangang [Univ. of Michigan, Ann Arbor, MI (United States)

    2009-04-01

    The past decade is one of the most exciting period in the history of physics and astronomy. The discovery of cosmic acceleration dramatically changed our understanding about the evolution and constituents of the Universe. To accommodate the new acceleration phase into our well established Big Bang cosmological scenario under the frame work of General Relativity, there must exist a very special substance that has negative pressure and make up about 73% of the total energy density in our Universe. It is called Dark Energy. For the first time people realized that the vast majority of our Universe is made of things that are totally different from the things we are made of. Therefore, one of the major endeavors in physics and astronomy in the coming years is trying to understand, if we can, the nature of dark energy. Understanding dark energy cannot be achieved from pure logic. We need empirical evidence to finally determine about what is dark energy. The better we can constrain the energy density and evolution of the dark energy, the closer we will get to the answer. There are many ways to constrain the energy density and evolution of dark energy, each of which leads to degeneracy in certain directions in the parameter space. Therefore, a combination of complimentary methods will help to reduce the degeneracies and give tighter constraints. Dark energy became dominate over matter in the Universe only very recently (at about z ~ 1.5) and will affect both the cosmological geometry and large scale structure formation. Among the various experiments, some of them constrain the dark energy mainly via geometry (such as CMB, Supernovae) while some others provides constraints from both structures and geometry (such as BAO, Galaxy Clusters) Galaxy clusters can be used as a sensitive probe for cosmology. A large cluster catalog that extends to high redshift with well measured masses is indispensable for precisely constraining cosmological parameters. Detecting clusters in optical

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

    Energy Technology Data Exchange (ETDEWEB)

    Nayyeri, H.; Mobasher, B.; Hemmati, S.; De Barros, S. [University of California Riverside, Riverside, CA 92512 (United States); Ferguson, H. C.; Wiklind, T.; Dahlen, T.; Kassin, S.; Koekemoer, A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Dickinson, M. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Giavalisco, M. [University of Massachusetts Amherst, Amherst, MA 01003 (United States); Fontana, A.; Paris, D. [INAF-Osservatorio Astronomico di Roma, Via Frascati 33 Monte Porzio Catone, 00040 Rome (Italy); Ashby, M.; Willner, S. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Barro, G.; Guo, Y. [University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Hathi, N. P. [Laboratoire d' Astrophysique de Marseille, rue Frédéric Joliot Curie, 13013 Marseille (France); Dunlop, J. S.; Targett, T. A. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom)

    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.

  18. A SIMPLE TECHNIQUE FOR PREDICTING HIGH-REDSHIFT GALAXY EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Behroozi, Peter S. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Silk, Joseph [Institut d' Astrophysique, UMR 7095 CNRS, Université Pierre et Marie Curie, 98bis Boulevard Arago, F-75014 Paris (France)

    2015-01-20

    We show that the ratio of galaxies' specific star formation rates (SSFRs) to their host halos' specific mass accretion rates (SMARs) strongly constrains how the galaxies' stellar masses, SSFRs, and host halo masses evolve over cosmic time. This evolutionary constraint provides a simple way to probe z > 8 galaxy populations without direct observations. Tests of the method with galaxy properties at z = 4 successfully reproduce the known evolution of the stellar mass-halo mass (SMHM) relation, galaxy SSFRs, and the cosmic star formation rate (CSFR) for 5 < z < 8. We then predict the continued evolution of these properties for 8 < z < 15. In contrast to the nonevolution in the SMHM relation at z < 4, the median galaxy mass at fixed halo mass increases strongly at z > 4. We show that this result is closely linked to the flattening in galaxy SSFRs at z > 2 compared to halo SMARs; we expect that average galaxy SSFRs at fixed stellar mass will continue their mild evolution to z ∼ 15. The expected CSFR shows no breaks or features at z > 8.5; this constrains both reionization and the possibility of a steep falloff in the CSFR at z = 9-10. Finally, we make predictions for stellar mass and luminosity functions for the James Webb Space Telescope, which should be able to observe one galaxy with M {sub *} ≳ 10{sup 8} M {sub ☉} per 10{sup 3} Mpc{sup 3} at z = 9.6 and one such galaxy per 10{sup 4} Mpc{sup 3} at z = 15.

  19. Photometric Properties of Low-Redshift Galaxy Clusters (LOCOS)

    CERN Document Server

    López-Cruz, O

    2000-01-01

    A comprehensive multicolor survey was undertaken to investigate global optical properties of Abell clusters of galaxies. This survey was christened the "Low-Redshift Cluster Optical Survey" (LOCOS). LOCOS was devised to search for patterns of galaxy evolution induced by the environment. The generated data base contains accurate deep CCD photometric measurements (Kron-Cousins R,,B and I) for a sample of 46 low-redshift (0.04 <= z <= 0.18) Abell clusters. This is one of the few large surveys that included the contribution due to dwarf galaxies (about 5.5 mag deeper than the R characteristic magnitude (M*); Ho=50 km/s/Mpc, qo=0). Due to space restrictions only the main results concerning the variations at the bright-end of the luminosity function (LF) are presented here. Other results are presented elsewhere (Lopez-Cruz & Yee 2000a,b). We have detected clear variations at both the bright end and the faint end of the LF. The nature of the variations at the bright end revealed that poor cD clusters have ...

  20. Galaxy bispectrum, primordial non-Gaussianity and redshift space distortions

    CERN Document Server

    Tellarini, Matteo; Tasinato, Gianmassimo; Wands, David

    2016-01-01

    Measurements of the non-Gaussianity of the primordial density field have the power to considerably improve our understanding of the physics of inflation. Indeed, if we can increase the precision of current measurements by an order of magnitude, a null-detection would rule out many classes of scenarios for generating primordial fluctuations. Large-scale galaxy redshift surveys represent experiments that hold the promise to realise this goal. Thus, we model the galaxy bispectrum and forecast the accuracy with which it will probe the parameter $f_{\\rm NL}$, which represents the degree of primordial local-type non Gaussianity. Specifically, we address the problem of modelling redshift space distortions (RSD) in the tree-level galaxy bispectrum including $f_{\\rm NL}$. We find novel contributions associated with RSD, with the characteristic large scale amplification induced by local-type non-Gaussianity. These RSD effects must be properly accounted for in order to obtain un-biased measurements of $f_{\\rm NL}$ from ...

  1. Galaxy groups in the 2MASS Redshift Survey

    CERN Document Server

    Lu, Yi; Shi, Feng; Mo, H J; Tweed, Dylan; Wang, Huiyuan; Zhang, Youcai; Li, Shijie; Lim, S H

    2016-01-01

    A galaxy group catalog is constructed from the 2MASS Redshift Survey (2MRS) with the use of a halo-based group finder. The halo mass associated with a group is estimated using a `GAP' method based on the luminosity of the central galaxy and its gap with other member galaxies. Tests using mock samples shows that this method is reliable, particularly for poor systems containing only a few members. On average 80% of all the groups have completeness >0.8, and about 65% of the groups have zero contamination. Halo masses are estimated with a typical uncertainty $\\sim 0.35\\,{\\rm dex}$. The application of the group finder to the 2MRS gives 29,904 groups from a total of 43,246 galaxies at $z \\leq 0.08$, with 5,286 groups having two or more members. Some basic properties of this group catalog is presented, and comparisons are made with other groups catalogs in overlap regions. With a depth to $z\\sim 0.08$ and uniformly covering about 91% of the whole sky, this group catalog provides a useful data base to study galaxies...

  2. AGN Host Galaxy Properties And Mass Function

    Science.gov (United States)

    Bongiorno, Angela

    2016-10-01

    Supermassive black hole growth, nuclear activity, and galaxy evolution have been found to be closely related. In the context of AGN-galaxy coevolution, I will discuss about the relation found between the host galaxy properties and the central BH and I will present the latest determination of the host galaxy stellar mass function (HGMF), and the specific accretion rate distribution function (SARDF), derived from the XMM-COSMOS sample up to z˜2.5, with particular focus on AGN feedback as possible responsible mechanism for galaxy quenching.

  3. High-Redshift galaxies light from the early universe

    CERN Document Server

    Appenzeller, Immo

    2008-01-01

    This book provides a comprehensive account of the scientific results on high-redshift galaxies accumulated during the past ten years. Apart from summarizing and critically discussing the wealth of observational data, the observational methods which made it possible to study these very distant and extremely faint objects are described in detail. Moreover, the technical feasibilities and physical limitations for existing and for future ground-based and space-based telescopes are discussed. Thus, apart from summarizing the knowledge accumulated so far, the book is designed as a tool for planning future observational and instrumental programs and projects. In view of the potential importance of the observational results of the high-redshift universe for basic physics the book is written for astronomers as well as for physicists without prior astronomical knowledge. For this purpose it contains introductory chapters describing the basic concepts and notations used in modern astronomy and a brief overview of the pr...

  4. DNF - Galaxy photometric redshift by Directional Neighbourhood Fitting

    Science.gov (United States)

    De Vicente, J.; Sánchez, E.; Sevilla-Noarbe, I.

    2016-07-01

    Wide field images taken in several photometric bands allow simultaneous measurement of redshifts for thousands of galaxies. A variety of algorithms to make this measurement have appeared in the last few years, the majority of which can be classified as either template- or training-based methods. Among the latter, nearest neighbour estimators stand out as one of the most successful, in terms of both precision and the quality of error estimation. In this paper we describe the Directional Neighbourhood Fitting (DNF) algorithm based on the following: a new neighbourhood metric (Directional Neighbourhood), a photo-z estimation strategy (Neighbourhood Fitting) and a method for generating the photo-z probability distribution function. We compare DNF with other well-known empirical photometric redshift tools using different public data sets (Sloan Digital Sky Survey, VIMOS VLT Deep Survey and Photo-z Accuracy Testing). DNF achieves high-quality results with reliable error.

  5. The Galaxy Count Correlation Function in Redshift Space Revisited

    Science.gov (United States)

    Campagne, J.-E.; Plaszczynski, S.; Neveu, J.

    2017-08-01

    In the near future, cosmology will enter the wide and deep galaxy survey era, enabling high-precision studies of the large-scale structure of the universe in three dimensions. To test cosmological models and determine their parameters accurately, it is necessary to use data with exact theoretical expectations expressed in observational parameter space (angles and redshift). The data-driven, galaxy number count fluctuations on redshift shells can be used to build correlation functions ξ (θ ,{z}1,{z}2) on and between shells to probe the baryonic acoustic oscillations and distance-redshift distortions, as well as gravitational lensing and other relativistic effects. To obtain a numerical estimation of ξ (θ ,{z}1,{z}2) from a cosmological model, it is typical to use either a closed form derived from a tripolar spherical expansion or to compute the power spectrum {C}{\\ell }({z}1,{z}2) and perform a Legendre polynomial {P}{\\ell }(\\cos θ ) expansion. Here, we present a new derivation of a ξ (θ ,{z}1,{z}2) closed form using the spherical harmonic expansion and proceeding to an infinite sum over multipoles thanks to an addition theorem. We demonstrate that this new expression is perfectly compatible with the existing closed forms but is simpler to establish and manipulate. We provide formulas for the leading density and redshift-space contributions, but also show how Doppler-like and lensing terms can be easily included in this formalism. We have implemented and made publicly available software for computing those correlations efficiently, without any Limber approximation, and validated this software with the CLASSgal code. It is available at https://gitlab.in2p3.fr/campagne/AngPow.

  6. Lyman alpha emitting galaxies at high redshift: Direct detection of young galaxies in a young universe

    Science.gov (United States)

    Dawson, Steven Arthur

    An early result of galaxy formation theory was the prediction that the copious ionizing radiation produced in nascent galaxies undergoing their first starbursts should in turn produce a strong Lya emission line. We report on our efforts to detect and characterize primeval galaxies by searching for this expected Lya signature with two observational techniques: serendipitous slit spectroscopy, and narrowband imaging selection. In Part I, we describe our serendipitous slit spectroscopy survey of the Hubble Deep Field and its environs, which resulted in a catalog of 74 spectroscopic redshifts spanning 0.10 5. Follow-up observations at higher resolution resulted in the additional serendipitous detection of a strong Lya-emitting galaxy at z = 5.190 (ES1). At the time of its discovery, ES1 was one of only nine known galaxies at z > 5, and was the sixth most distant known galaxy. The unprecedented spectral purity of the observation offers evidence for a galaxy-scale outflow with a. velocity of v > 300 km s -1 , consistent with wind speeds observed in powerful local starbursts (typically 10 2 to 10 3 km s -1 ), and with simulations of the late- stage evolution of Lya emission in star-forming systems. Our final serendipitous detection is the remarkable source CXOHDFN J123635.6+621424, which is both the highest redshift known spiral galaxy, and a rare example of a high redshift, hard X-ray-emitting Type II AGN. Significantly, all of these results were acquired with no direct allocation of telescope time. In Part II, we report on our implementation of narrowband imaging selection, with which we traded redshift coverage for survey volume, focusing on the systematic study of galaxies at a particular epoch in favor of chasing that rare, most-distant object. This effort resulted in a catalog of 76 z [approximate] 4.5 Lya-emitting galaxies spectroscopically-confirmed in campaigns of Keck/LRIS and Keck/DEIMOS follow-up observations to candidates selected in the Large Area Lyman

  7. Color and Polarization Models of High Redshift Radio Galaxies

    Science.gov (United States)

    Chambers, K. C.

    2000-05-01

    The scattering of an anisotropic quasar beam by dust swept-up by a bipolar outflow is used to construct model color and polarization images for comparison with high redshift radio galaxies and quasars. The swept-up shell is assumed to be optically thin to dust scattering outside the nuclear region. The spectral energy distributions and polarization characteristics of the extended aligned emission from HZRGs and QSRs can be reproduced using an input quasar spectrum and the Loar & Draine (1993) silicate-graphite grain model.

  8. The MOSDEF Survey: AGN Multi-wavelength Identification, Selection Biases, and Host Galaxy Properties

    Science.gov (United States)

    Azadi, Mojegan; Coil, Alison L.; Aird, James; Reddy, Naveen; Shapley, Alice; Freeman, William R.; Kriek, Mariska; Leung, Gene C. K.; Mobasher, Bahram; Price, Sedona H.; Sanders, Ryan L.; Shivaei, Irene; Siana, Brian

    2017-01-01

    We present results from the MOSFIRE Deep Evolution Field (MOSDEF) survey on the identification, selection biases, and host galaxy properties of 55 X-ray, IR, and optically selected active galactic nuclei (AGNs) at 1.4optical spectra of galaxies and AGNs and use the BPT diagram to identify optical AGNs. We examine the uniqueness and overlap of the AGNs identified at different wavelengths. There is a strong bias against identifying AGNs at any wavelength in low-mass galaxies, and an additional bias against identifying IR AGNs in the most massive galaxies. AGN hosts span a wide range of star formation rates (SFRs), similar to inactive galaxies once stellar mass selection effects are accounted for. However, we find (at ∼2–3σ significance) that IR AGNs are in less dusty galaxies with relatively higher SFR and optical AGNs in dusty galaxies with relatively lower SFR. X-ray AGN selection does not display a bias with host galaxy SFR. These results are consistent with those from larger studies at lower redshifts. Within star-forming galaxies, once selection biases are accounted for, we find AGNs in galaxies with similar physical properties as inactive galaxies, with no evidence for AGN activity in particular types of galaxies. This is consistent with AGNs being fueled stochastically in any star-forming host galaxy. We do not detect a significant correlation between SFR and AGN luminosity for individual AGN hosts, which may indicate the timescale difference between the growth of galaxies and their supermassive black holes.

  9. Structure and mass distribution of spiral galaxies at intermediate redshifts

    CERN Document Server

    Tamm, A; Tamm, Antti; Tenjes, Peeter

    2003-01-01

    Using the HST archive WFPC2 observations and rotation curves measeured by Vogt et al. (1996), we constructed self-consistent light and mass distribution models for three disk galaxies at redshifts z = 0.15, 0.90 and 0.99. The models consist of three components: the bulge, the disk and the dark matter. Spatial density distribution parameters for the components were calculated. After applying k-corrections, mass-to-light ratios for galactic disks within the maximum disk assumption are M/L_B = 4.4, 1.2 and 1.2, respectively. Corresponding central densities of dark matter halos within a truncated isothermal model are 0.0092, 0.028 and 0.015 in units M_sol/pc^3. The light distribution of galaxies in outer parts is steeper than a simple exponential disk.

  10. High redshift galaxies in the ALHAMBRA survey . I. Selection method and number counts based on redshift PDFs

    Science.gov (United States)

    Viironen, K.; Marín-Franch, A.; López-Sanjuan, C.; Varela, J.; Chaves-Montero, J.; Cristóbal-Hornillos, D.; Molino, A.; Fernández-Soto, A.; Vilella-Rojo, G.; Ascaso, B.; Cenarro, A. J.; Cerviño, M.; Cepa, J.; Ederoclite, A.; Márquez, I.; Masegosa, J.; Moles, M.; Oteo, I.; Pović, M.; Aguerri, J. A. L.; Alfaro, E.; Aparicio-Villegas, T.; Benítez, N.; Broadhurst, T.; Cabrera-Caño, J.; Castander, J. F.; Del Olmo, A.; González Delgado, R. M.; Husillos, C.; Infante, L.; Martínez, V. J.; Perea, J.; Prada, F.; Quintana, J. M.

    2015-04-01

    Context. Most observational results on the high redshift restframe UV-bright galaxies are based on samples pinpointed using the so-called dropout technique or Ly-α selection. However, the availability of multifilter data now allows the dropout selections to be replaced by direct methods based on photometric redshifts. In this paper we present the methodology to select and study the population of high redshift galaxies in the ALHAMBRA survey data. Aims: Our aim is to develop a less biased methodology than the traditional dropout technique to study the high redshift galaxies in ALHAMBRA and other multifilter data. Thanks to the wide area ALHAMBRA covers, we especially aim at contributing to the study of the brightest, least frequent, high redshift galaxies. Methods: The methodology is based on redshift probability distribution functions (zPDFs). It is shown how a clean galaxy sample can be obtained by selecting the galaxies with high integrated probability of being within a given redshift interval. However, reaching both a complete and clean sample with this method is challenging. Hence, a method to derive statistical properties by summing the zPDFs of all the galaxies in the redshift bin of interest is introduced. Results: Using this methodology we derive the galaxy rest frame UV number counts in five redshift bins centred at z = 2.5,3.0,3.5,4.0, and 4.5, being complete up to the limiting magnitude at mUV(AB) = 24, where mUV refers to the first ALHAMBRA filter redwards of the Ly-α line. With the wide field ALHAMBRA data we especially contribute to the study of the brightest ends of these counts, accurately sampling the surface densities down to mUV(AB) = 21-22. Conclusions: We show that using the zPDFs it is easy to select a very clean sample of high redshift galaxies. We also show that it is better to do statistical analysis of the properties of galaxies using a probabilistic approach, which takes into account both the incompleteness and contamination issues in a

  11. The host galaxies of BL Lac objects in the near-infrared

    CERN Document Server

    Kotilainen, J K; Scarpa, R

    1998-01-01

    We present the results of near-infrared H band (1.65 microns) imaging of 11 BL Lac objects with redshifts ranging from z = 0.05 to 0.9. We are able to clearly detect the host galaxy in seven low redshift (z<=0.24) BL Lacs, while the four unresolved BL Lacs have either high or unknown redshift. The galaxies hosting the low redshift BL Lacs are large (average bulge scale length R(e) = 8.8+-9.9 kpc) and luminous (average M(H) = -25.8+-0.5), i.e. slightly brighter than the typical galaxy luminosity L* (M*(H) = -25.0+-0.2), and of similar luminosity to or slightly fainter than brightest cluster galaxies (M(H) = -26.3+-0.3). The average optical/near-infrared colour and colour gradient of the BL Lac hosts (R-H = 2.2+-0.5; d(R-H)/d(log r) = -0.09$+-0.04) are consistent with the hosts being normal ellipticals, indicating that the nuclear activity has only a marginal effect on the star formation history and other properties of the hosts. The BL Lac hosts appear slightly less luminous than those of higher redshift fl...

  12. Gemini imaging of QSO host galaxies at z~2

    CERN Document Server

    Croom, S; Boyle, B; Shanks, T; Miller, L; Smith, R; Croom, Scott; Schade, David; Boyle, Brian; Shanks, Tom; Miller, Lance; Smith, Robert

    2004-01-01

    We present results of a Gemini adaptive optics (AO) imaging program to investigate the host galaxies of typical QSOs at z~2. Our aim is to study the host galaxies of typical, L*_qso QSOs at the epoch of peak QSO and star formation activity. The large database of faint QSOs provided by the 2dF QSO Redshift Survey allows us to select a sample of QSOs at z=1.75-2.5 which have nearby (<12 arcsecond separation) bright stars suitable for use as AO guide stars. We have observed a sample of 9 QSOs. The images of these sources have AO corrected full-width at half-maximum of between 0.11 and 0.25 arcseconds. We use multiple observations of point spread function (PSF) calibration star pairs in order to quantify any uncertainty in the PSF. We then factored these uncertainties into our modelling of the QSO plus host galaxy. In only one case did we convincingly detect a host (2QZ J133311.4+001949, at z=1.93). This host galaxy has K=18.5+-0.2 mag with a half-light radius, r_e=0.55+-0.1'', equivalent to ~3L*_gal assuming ...

  13. The extremely red host galaxy of GRB 080207

    CERN Document Server

    Hunt, Leslie; Rossi, Andrea; Savaglio, Sandra; Cresci, Giovanni; Klose, Sylvio; Michalowski, Michal; Pian, Elena

    2011-01-01

    We present optical, near-infrared, and Spitzer IRAC and MIPS observations of the host galaxy of the dark gamma-ray burst GRB 080207. The host is faint, with extremely red optical-infrared colors ($R-K\\,=\\,6.3$, 24\\micron/$R-$band flux $\\sim1000$) making it an extremely red object (ERO) and a dust-obscured galaxy (DOG). The spectral energy distribution (SED) shows the clear signature of the 1.6 micron photometric "bump", typical of evolved stellar populations. We use this bump to establish the photometric redshift $z_{\\rm phot}$ as 2.2$^{+0.2}_{-0.3}$, using a vast library of SED templates, including M 82. The star-formation rate (SFR) inferred from the SED fitting is $\\sim$119\\msun\\,yr$^{-1}$, the stellar mass $3\\times10^{11}$\\,\\msun, and \\av\\ extinction from 1-2\\,mag. The ERO and DOG nature of the host galaxy of the dark GRB 080207 may be emblematic of a distinct class of dark GRB hosts, with high SFRs, evolved and metal-rich stellar populations, and significant dust extinction within the host galaxy.

  14. Estimating Luminosities and Stellar Masses of Galaxies Photometrically without Determining Redshifts

    CERN Document Server

    Hsieh, B C

    2014-01-01

    Large direct-imaging surveys usually use a template-fitting technique to estimate photometric redshifts for galaxies, which are then applied to derive important galaxy properties such as luminosities and stellar masses. These estimates can be noisy and suffer from systematic biases because of the possible mis-selection of templates and the propagation of the photometric redshift uncertainty. We introduce an algorithm, the Direct Empirical Photometric method (DEmP), which can be used to directly estimate these quantities using training sets, bypassing photometric redshift determination. DEmP also applies two techniques to minimize the effects arising from the non-uniform distribution of training-set galaxy redshifts from a flux-limited sample. First, for each input galaxy, fitting is performed using a subset of the training-set galaxies with photometry and colors closest to those of the input galaxy. Second, the training set is artificially resampled to produce a flat distribution in redshift, or other propert...

  15. NEARBY CLUMPY, GAS RICH, STAR-FORMING GALAXIES: LOCAL ANALOGS OF HIGH-REDSHIFT CLUMPY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Garland, C. A. [Natural Sciences Department, Jeffords Science Center, Castleton State College, Castleton, VT 05735 (United States); Pisano, D. J.; Rabidoux, K. [Department of Physics and Astronomy, West Virginia University, 135 Willey Street, P.O. Box 6315, Morgantown, WV 26506 (United States); Low, M.-M. Mac [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Kreckel, K. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Guzmán, R., E-mail: catherine.garland@castleton.edu, E-mail: djpisano@mail.wvu.edu, E-mail: krabidou@mix.wvu.edu, E-mail: mordecai@amnh.org, E-mail: kreckel@mpia.de, E-mail: guzman@astro.ufl.edu [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, P.O. Box 112055, Gainesville, FL 32611 (United States)

    2015-07-10

    Luminous compact blue galaxies (LCBGs) have enhanced star formation rates (SFRs) and compact morphologies. We combine Sloan Digital Sky Survey data with H i data of 29 LCBGs at redshift z ∼ 0 to understand their nature. We find that local LCBGs have high atomic gas fractions (∼50%) and SFRs per stellar mass consistent with some high-redshift star-forming galaxies (SFGs). Many local LCBGs also have clumpy morphologies, with clumps distributed across their disks. Although rare, these galaxies appear to be similar to the clumpy SFGs commonly observed at z ∼ 1–3. Local LCBGs separate into three groups: (1) interacting galaxies (∼20%); (2) clumpy spirals (∼40%); and (3) non-clumpy, non-spirals with regular shapes and smaller effective radii and stellar masses (∼40%). It seems that the method of building up a high gas fraction, which then triggers star formation, is not the same for all local LCBGs. This may lead to a dichotomy in galaxy characteristics. We consider possible gas delivery scenarios and suggest that clumpy spirals, preferentially located in clusters and with companions, are smoothly accreting gas from tidally disrupted companions and/or intracluster gas enriched by stripped satellites. Conversely, as non-clumpy galaxies are preferentially located in the field and tend to be isolated, we suggest clumpy, cold streams, which destroy galaxy disks and prevent clump formation, as a likely gas delivery mechanism for these systems. Other possibilities include smooth cold streams, a series of minor mergers, or major interactions.

  16. Cosmic dichotomy in the hosts of rapidly star-forming systems at low and high redshifts

    CERN Document Server

    Magliocchetti, Manuela; Negrello, Mattia; De Zotti, Gianfranco; Danese, Luigi

    2013-01-01

    This paper presents a compilation of clustering results taken from the literature for galaxies with highly enhanced (SFR [30-10^3] Msun/yr) star formation activity observed in the redshift range z=[0-3]. We show that, irrespective of the selection technique and only very mildly depending on the star forming rate, the clustering lengths of these objects present a sharp increase of about a factor 3 between z~1 and z~2, going from values of ~5 Mpc to about 15 Mpc and higher. This behaviour is reflected in the trend of the masses of the dark matter hosts of star-forming galaxies which increase from ~10^11.5 Msun to ~10^13.5 Msun between z~1 and z~2. Our analysis shows that galaxies which actively form stars at high redshifts are not the same population of sources we observe in the more local universe. In fact, vigorous star formation in the early universe is hosted by very massive structures, while for z~1 a comparable activity is encountered in much smaller systems, consistent with the down-sizing scenario. The ...

  17. An Increasing Stellar Baryon Fraction in Bright Galaxies at High Redshift

    CERN Document Server

    Finkelstein, Steven L; Behroozi, Peter; Somerville, Rachel S; Papovich, Casey; Milosavljevic, Milos; Dekel, Avishai; Narayanan, Desika; Ashby, Matthew L N; Cooray, Asantha; Fazio, Giovanni G; Ferguson, Henry C; Koekemoer, Anton M; Salmon, Brett W; Willner, S P

    2015-01-01

    Recent observations have shown that the characteristic luminosity of the rest-frame ultraviolet (UV) luminosity function does not significantly evolve at 4 < z < 7 and is approximately M*_UV ~ -21. We investigate this apparent non-evolution by examining a sample of 190 bright, M_UV < -21 galaxies at z=4 to 7, analyzing their stellar populations and host halo masses. Including deep Spitzer/IRAC imaging to constrain the rest-frame optical light, we find that M*_UV galaxies at z=4-7 have similar stellar masses of log(M/Msol)=9.8-9.9 and are thus relatively massive for these high redshifts. However, bright galaxies at z=4-7 are less massive and have younger inferred ages than similarly bright galaxies at z=2-3, even though the two populations have similar star formation rates and levels of dust attenuation. We match the abundances of these bright z=4-7 galaxies to halo mass functions from the Bolshoi Lambda-CDM simulation to estimate the halo masses. We find that the typical halo masses in ~M*_UV galaxie...

  18. The redshift evolution of the stellar populations in elliptical galaxies

    CERN Document Server

    Bender, R; Bruzual, A G; Bender, Ralf; Ziegler, Bodo; Bruzual, Gustavo

    1996-01-01

    Velocity dispersions \\sigma and Mg absorption line-strengths Mg_b have been measured for a sample of 16 ellipticals in 3 clusters at a redshift of 0.37. Like local cluster ellipticals, these objects show a correlation between Mg_b and \\sigma. However, at any given \\sigma, the mean Mg_b of the ellipticals at z=0.37 is weaker than the mean Mg_b of their local relatives in the Coma and Virgo clusters. The Mg_b weakening is smallest for the most luminous ellipticals and larger for the fainter objects. This is unambiguous evidence for {\\it small but significant passive evolution} of the stellar populations of elliptical galaxies with redshift. It requires that the bulk of the stars in cluster ellipticals has formed at z>2. The most luminous objects may even have formed at z>4. The Mg_b-\\sigma test is a very reliable estimator for the evolution of old stellar populations because it is virtually independent from the stellar initial mass function (IMF) and from the metallicities of the galaxies. Furthermore, the infl...

  19. Probing neutrino masses with future galaxy redshift surveys

    CERN Document Server

    Lesgourgues, Julien; Perotto, Laurence; Lesgourgues, Julien; Pastor, Sergio; Perotto, Laurence

    2004-01-01

    We perform a new study of future sensitivities of galaxy redshift surveys to the free-streaming effect caused by neutrino masses, adding the information on cosmological parameters from measurements of primary anisotropies of the cosmic microwave background (CMB). Our reference cosmological scenario has nine parameters and three different neutrino masses, with a hierarchy imposed by oscillation experiments. Within the present decade, the combination of the Sloan Digital Sky Survey (SDSS) and CMB data from the PLANCK experiment will have a 2-sigma detection threshold on the total neutrino mass close to 0.2 eV. This estimate is robust against the inclusion of extra free parameters in the reference cosmological model. On a longer term, the next generation of experiments may reach values of order sum m_nu = 0.1 eV at 2-sigma, or better if a galaxy redshift survey significantly larger than SDSS is completed. We also discuss how the small changes on the free-streaming scales in the normal and inverted hierarchy sche...

  20. Southern Sky Redshift Survey: Clustering of Local Galaxies

    Science.gov (United States)

    Willmer, Christopher N. A.; da Costa, Luiz Nicolaci; Pellegrini, Paulo S.

    1998-03-01

    We use the two-point correlation function to calculate the clustering properties of the recently completed SSRS2 survey, which probes two well-separated regions of the sky, allowing one to evaluate the sensitivity of sample-to-sample variations. Taking advantage of the large number of galaxies in the combined sample, we also investigate the dependence of clustering on the internal properties of galaxies. The redshift-space correlation function for the combined magnitude-limited sample of the SSRS2 is given by xi(s) = [s/(5.85 h^-1 Mpc)]^-1.60 for separations in the range 2 h^-1 Mpc b b is the linear biasing factor for optical galaxies. We have used the SSRS2 sample to study the dependence of xi on the internal properties of galaxies, such as luminosity, morphology, and color. We confirm earlier results that luminous galaxies (L > L^*) are more clustered than sub-L^* galaxies and that the luminosity segregation is scale-independent. We also find that early types are more clustered than late types. However, in the absence of rich clusters, the relative bias between early and late types in real space, b_E+S0/b_S ~ 1.2, is not as strong as previously estimated. Furthermore, both morphologies present a luminosity-dependent bias, with the early types showing a slightly stronger dependence on luminosity. We also find that red galaxies are significantly more clustered than blue ones, with a mean relative bias of b_R/b_B ~ 1.4, stronger than that observed for morphology. Finally, by comparing our results with the measurements obtained from the infrared-selected galaxies, we determine that the relative bias between optical and IRAS galaxies in real space is b_o/b_I ~ 1.4. Based on observations obtained at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation; Complejo Astronómico El Leoncito, operated

  1. Distribution of streaming rates into high-redshift galaxies

    CERN Document Server

    Goerdt, Tobias; Dekel, Avishai; Teyssier, Romain

    2015-01-01

    We study the accretion along streams from the cosmic web into high-redshift massive galaxies using three sets of AMR hydro-cosmological simulations. We find that the streams keep a roughly constant accretion rate as they penetrate into the halo centre. The mean accretion rate follows the mass and redshift dependence predicted for haloes by the EPS approximation, dM / dt is proportional to Mvir^{1.25} (1 + z)^{2.5}. The distribution of the accretion rates can well be described by a sum of two Gaussians, the primary corresponding to "smooth inflow" and the secondary to "mergers". The same functional form was already found for the distributions of specific star formation rates in observations. The mass fraction in the smooth component is 60 - 90 %, insensitive to redshift or halo mass. The simulations with strong feedback show clear signs of re-accretion due to recycling of galactic winds. The mean accretion rate for the mergers is a factor 2 - 3 larger than that of the smooth component. The standard deviation o...

  2. AGN Host Galaxy Properties and Mass Function

    OpenAIRE

    Bongiorno, Angela

    2016-01-01

    Supermassive black hole growth, nuclear activity, and galaxy evolution have been found to be closely related. In the context of AGN-galaxy coevolution, I will discuss about the relation found between the host galaxy properties and the central BH and I will present the latest determination of the host galaxy stellar mass function (HGMF), and the specific accretion rate distribution function (SARDF), derived from the XMM-COSMOS sample up to z∼2.5, with particular focus on AGN feedback as possib...

  3. Star-forming galaxies in low-redshift clusters: Data and integrated galaxy properties

    CERN Document Server

    Thomas, C F; James, P A; Bennett, S M; Aragón-Salamanca, A; Whittle, M

    2008-01-01

    This paper is a continuation of an ongoing study of the evolutionary processes affecting cluster galaxies. Both CCD R band and H alpha narrow-band imaging was used to determine photometric parameters (m_(r), r_(24), H alpha flux and equivalent width) and derive star formation rates for 227 CGCG galaxies in 8 low-redshift clusters. The galaxy sample is a subset of CGCG galaxies in an objective prism survey of cluster galaxies for H alpha emission. It is found that detection of emission-line galaxies in the OPS is 85%, 70%, and 50% complete at the mean surface brightness values of 1.25 x 10^(-19), 5.19 x 10^(-20), and 1.76 x 10^(-20) W m^(-2) arcsec^(-2), respectively, measured within the R band isophote of 24 mag arcsec^(-2) for the galaxy. The CCD data, together with matched data from a recent H alpha galaxy survey of UGC galaxies within 3000 km s^(-1), will be used for a comparative study of R band and H alpha surface photometry between cluster and field spirals.

  4. Simple stellar population modelling of low S/N galaxy spectra and quasar host galaxy applications

    Science.gov (United States)

    Mosby, G.; Tremonti, C. A.; Hooper, E. J.; Wolf, M. J.; Sheinis, A. I.; Richards, J. W.

    2015-02-01

    To study the effect of supermassive black holes (SMBHs) on their host galaxies it is important to study the hosts when the SMBH is near its peak activity. A method to investigate the host galaxies of high luminosity quasars is to obtain optical spectra at positions offset from the nucleus where the relative contribution of the quasar and host is comparable. However, at these extended radii the galaxy surface brightness is often low (20-22 mag arcsec-2) and the resulting spectrum might have such low signal-to-noise ratio (S/N) that it hinders analysis with standard stellar population modelling techniques. To address this problem, we have developed a method that can recover galaxy star formation histories (SFHs) from rest-frame optical spectra with S/N ˜ 5 Å-1. This method uses the statistical technique diffusion k-means to tailor the stellar population modelling basis set. Our diffusion k-means minimal basis set, composed of four broad age bins, is successful in recovering a range of galaxy SFHs. Additionally, using an analytic prescription for seeing conditions, we are able to simultaneously model scattered quasar light and the SFH of quasar host galaxies (QHGs). We use synthetic data to compare results of our novel method with previous techniques. We also present the modelling results on a previously published QHG and show that galaxy properties recovered from a diffusion k-means basis set are less sensitive to noise added to this QHG spectrum. Our new method has a clear advantage in recovering information from QHGs and could also be applied to the analysis of other low S/N galaxy spectra such as those typically obtained for high redshift objects or integral field spectroscopic surveys.

  5. Simultaneous Constraints on Cosmology and Photometric Redshift Bias from Weak Lensing and Galaxy Clustering

    CERN Document Server

    Samuroff, S; Bridle, SL; Zuntz, J; MacCrann, N; Krause, E; Eifler, T; Kirk, D

    2016-01-01

    We investigate the expected cosmological constraints from a combination of weak lensing and large-scale galaxy clustering using realistic redshift distributions. Introducing a systematic bias in the weak lensing redshift distributions (of 0.05 in redshift) produces a $>2\\sigma$ bias in the recovered matter power spectrum amplitude and dark energy equation of state, for preliminary Stage III surveys. We demonstrate that these cosmological errors can be largely removed by marginalising over unknown biases in the assumed weak lensing redshift distributions, if we assume high quality redshift information for the galaxy clustering sample. Furthermore the cosmological constraining power is mostly retained despite removing much of the information on the weak lensing redshift distribution biases. We show that this comes from complementary degeneracy directions between cosmic shear and the combination of galaxy clustering with cross-correlation between shear and galaxy number density. Finally we examine how the self-c...

  6. The host of GRB 060206: kinematics of a distant galaxy

    CERN Document Server

    Thoene, Christina C; Ledoux, Cedric; Starling, Rhaana L C; Fynbo, Johan P U; Curran, Peter A; Gorosabel, Javier; van der Horst, Alexander J; Kewley, Lisa J; Levan, Andrew J; LLorente, Alvaro; Rol, Evert; Tanvir, Nial R; Postigo, Antonio de Ugarte; Vreeswijk, Paul M; Wijers, Ralph A M J

    2007-01-01

    Context. The spectra of afterglows can provide us with detailed information on the line-of-sight towards high redshift gamma-ray bursts (GRBs). This allows us to use GRB afterglows as sensitive probes of interstellar matter in their host galaxies, and the circumstellar material around the progenitor star. Aims. In this paper we present early WHT/ISIS optical spectroscopy of the afterglow of the gamma-ray burst GRB 060206 at z = 4.048, detecting a range of metal absorption lines and their fine-structure transitions. Additional information is provided by properties derived from the afterglow lightcurve and from deep imaging of the host galaxy. Methods. The resolution and wavelength range of the spectra and the bright afterglow facilitate a detailed study of the circumburst and host galaxy environment through fitting of the absorption line systems. Their column densities allow us to derive properties for the different detected velocity components. We also use the deep imaging to detect the host galaxy and probe ...

  7. Selection and Physical Properties of High-redshift Galaxies

    Science.gov (United States)

    Fang, G. W.

    2014-09-01

    Extremely Red Objects (EROs) and BzKs continue to attract considerable interest. It has been suggested that they may be the direct progenitors of present-day massive E/S0 galaxies, and can provide crucial constraints on the current galaxy formation and evolution models. Therefore, the key question is to measure the relative fraction of OGs (old galaxies) and DGs (young, and dusty starburst galaxies) in the sample of EROs. Many groups have been currently investigating the fractions of these two ERO populations using a variety of observational approaches, but the fraction of OGs and DGs from different surveys is different. In the meantime, a number of observations suggest that the epoch of z˜2 also plays an important role in galaxy formation and evolution for various reasons: the cosmic star formation rate density (SFRD) begins to drop at z˜2 from a flat plateau at higher redshifts; the morphological type mix of field galaxies changes remarkably at z˜2; the number density of QSOs has a peak at z˜2; and about 50% to 70% of the stellar mass assembly of galaxies took place in the redshift range 1thesis, our main works are as follows: (1) the classification of z˜1 EROs in the UDF and COSMOS field, (2) a study on physical properties of passive and star-forming galaxies at z˜2 in the AEGIS field, and (3) the mid-infrared spectroscopy and multi-wavelength study of ultraluminous infrared galaxies (ULIRGs) at z˜2 in the AEGIS field. Chapter 1 gives a brief review on the research progresses of EROs at z˜1, BzKs at z˜2, and ULIRGs at z˜2, respectively. In Chapter 2 we present a quantitative study of the classification of EROs in the UDF and COSMOS field. Our sample includes 5264 (COSMOS, K_{Vega} ≤19.2) and 24 EROs (UDF, K_{Vega}≤22.0) with (i-K)_{AB}≥2.45. Using the fitting method of spectral energy distribution (SED), [3.6]-[8.0] color, and the nonparametric measures of galaxy morphology, we classify EROs into two classes: DGs and OGs. We find that the

  8. CLASH: Extreme Emission Line Galaxies and Their Implication on Selection of High-Redshift Galaxies

    CERN Document Server

    Huang, Xingxing; Wang, Junxian; Ford, Holland; Lemze, Doron; Moustakas, John; Shu, Xinwen; Van der Wel, Arjen; Zitrin, Adi; Frye, Brenda L; Postman, Marc; Bartelmann, Matthias; Benitez, Narciso; Bradley, Larry; Broadhurst, Tom; Coe, Dan; Donahue, Megan; Infante, Leopoldo; Kelson, Daniel; Koekemoer, Anton; Lahav, Ofer; Medezinski, Elinor; Moustakas, Leonidas; Rosati, Piero; Seitz, Stella; Umetsu, Keiichi

    2014-01-01

    We utilize the CLASH (Cluster Lensing And Supernova survey with Hubble) observations of 25 clusters to search for extreme emission-line galaxies (EELGs). The selections are carried out in two central bands: F105W (Y105) and F125W (J125), as the flux of the central bands could be enhanced by the presence of [O III] 4959, 5007 at redshift of about 0.93-1.14 and 1.57-1.79, respectively. The multi-band observations help to constrain the equivalent widths of emission lines. Thanks to cluster lensing, we are able to identify 52 candidates down to an intrinsic limiting magnitude of 28.5 and to a rest-frame [O III] 4959,5007 equivalent width of about 3737 angstrom. Our samples include a number of EELGs at lower luminosities that are missed in other surveys, and the extremely high equivalent width can be only found in such faint galaxies. These EELGs can mimic the dropout feature similar to that of high redshift galaxies and contaminate the color-color selection of high redshift galaxies when the S/N ratio is limited ...

  9. CLASH: EXTREME EMISSION-LINE GALAXIES AND THEIR IMPLICATION ON SELECTION OF HIGH-REDSHIFT GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xingxing; Wang, Junxian; Shu, Xinwen [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zheng, Wei; Ford, Holland; Lemze, Doron [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Moustakas, John [Department of Physics and Astronomy, Siena College, 515 Loudon Road, Loudonville, NY 12211 (United States); Van der Wel, Arjen [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117, Heidelberg (Germany); Zitrin, Adi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Frye, Brenda L. [Steward Observatory/Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Postman, Marc; Bradley, Larry; Coe, Dan [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21208 (United States); Bartelmann, Matthias [Leiden Observatory, Leiden University, P. O. Box 9513, 2300 RA Leiden (Netherlands); Benítez, Narciso [Instituto de Astrofísica de Andalucía (CSIC), C/Camino Bajo de Huétor 24, Granada E-18008 (Spain); Broadhurst, Tom [Department of Theoretical Physics, University of Basque Country UPV/EHU E-Bilbao (Spain); Donahue, Megan [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Infante, Leopoldo, E-mail: hxx@mail.ustc.edu.cn [Departamento de Astronoía y Astrofísica, Pontificia Universidad Católica de Chile, V. Mackenna 4860 Santiago 22 (Chile); and others

    2015-03-01

    We utilize the Cluster Lensing And Supernova survey with Hubble observations of 25 clusters to search for extreme emission-line galaxies (EELGs). The selections are carried out in two central bands: F105W (Y {sub 105}) and F125W (J {sub 125}), as the flux of the central bands could be enhanced by the presence of [O III] λλ4959, 5007 at redshifts of ∼0.93-1.14 and 1.57-1.79, respectively. The multiband observations help to constrain the equivalent widths (EWs) of emission lines. Thanks to cluster lensing, we are able to identify 52 candidates down to an intrinsic limiting magnitude of 28.5 and to a rest-frame [O III] λλ4959, 5007 EW of ≅ 3700 Å. Our samples include a number of EELGs at lower luminosities that are missed in other surveys, and the extremely high EW can only be found in such faint galaxies. These EELGs can mimic a dropout feature similar to that of high-redshift galaxies and contaminate the color-color selection of high-redshift galaxies when the signal-to-noise ratio is limited or the band coverage is incomplete.

  10. The Luminosity Function of Low-Redshift Abell Galaxy Clusters

    CERN Document Server

    Barkhouse, Wayne A; López-Cruz, Omar

    2007-01-01

    We present the results from a survey of 57 low-redshift Abell galaxy clusters to study the radial dependence of the luminosity function (LF). The dynamical radius of each cluster, r200, was estimated from the photometric measurement of cluster richness, Bgc. The shape of the LFs are found to correlate with radius such that the faint-end slope, alpha, is generally steeper on the cluster outskirts. The sum of two Schechter functions provides a more adequate fit to the composite LFs than a single Schechter function. LFs based on the selection of red and blue galaxies are bimodal in appearance. The red LFs are generally flat for -22 -18. The blue LFs contain a larger contribution from faint galaxies than the red LFs. The blue LFs have a rising faint-end component (alpha ~ -1.7) for M_Rc > -21, with a weaker dependence on radius than the red LFs. The dispersion of M* was determined to be 0.31 mag, which is comparable to the median measurement uncertainty of 0.38 mag. This suggests that the bright-end of the LF is...

  11. What are the galaxies that host MIR-selected AGN?

    Science.gov (United States)

    Rosario, David

    2016-08-01

    Infra-red selection techniques, sensitive to dust strongly heated by an AGN, offer a way to identify some of the most obscured accretion events in the Universe. I will describe the results of a comprehensive multi-wavelength study of AGN to z>2 selected using Spitzer/IRAC based methods in the COSMOS field. Armed with AGN-optimised redshifts and stellar masses, we explore the dust emission from the active nucleus and the host galaxy. We demonstrate that IR-selected AGN tend to be found in low mass host galaxies, when compared to other AGN identification methods. The star-formation rates of obscured and unobscured IR-selected AGN are very similar, implying that large-scale obscuration with co-eval star-bursts are not found in a major proportion of heavily obscured AGN.

  12. Star Formation in Intermediate Redshift 0.2 < Z < 0.7 Brightest Cluster Galaxies

    CERN Document Server

    Cooke, Kevin C; Baum, Stefi A; Tremblay, Grant R; Cox, Isabella G; Gladders, Michael D

    2016-01-01

    We present a multi-wavelength photometric and spectroscopic study of 42 Brightest Cluster Galaxies (BCGs) in two samples of clusters of galaxies chosen for the study of gravitational lensing. The study's initial sample combines 25 BCGs from the Cluster Lensing and Supernova Survey with Hubble (CLASH) sample and 37 BCGs from the Sloan Giant Arcs Survey (SGAS) with a total redshift range of 0.2 < Z < 0.7. Using archival GALEX, HST, WISE, Herschel, and VLA data we determine the BCGs' stellar mass, radio power, and star formation rates. The radio power is higher than expected if due to star formation, consistent with the BCGs being AGN-powered radio sources. This suggests that the AGN and star formation are both fueled by cold gas in the host galaxy. The specific star formation rate (sSFR) is low and constant with redshift. The mean sSFR is 9.42 * 10^-12 yr^-1 which corresponds to a mass doubling time of 105 billion years. These findings are consistent with models for hierarchical formation of BCGs which su...

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

    Science.gov (United States)

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

    2013-06-01

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

  14. HOST GALAXIES OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY

    Energy Technology Data Exchange (ETDEWEB)

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J. [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Kerschhaggl, M.; Kowalski, M. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon (France); Universite de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucleaire de Lyon (France); and others

    2013-06-20

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

  15. Structures of Local Galaxies Compared to High Redshift Star-forming Galaxies

    CERN Document Server

    Petty, Sara M; Gallagher, John S; Gardner, Jonathan P; Lotz, Jennifer M; Mountain, C Matt; Smith, Linda J

    2009-01-01

    The rest-frame far-ultraviolet (FUV) morphologies of 8 nearby interacting and starburst galaxies (Arp 269, M 82, Mrk 8, NGC 520, NGC 1068, NGC 3079, NGC 3310, NGC 7673) are compared with 54 galaxies at z ~ 1.5 and 46 galaxies at z ~ 4 observed in the GOODS-ACS field. The nearby sample is artificially redshifted to z ~ 1.5 and 4. We compare the simulated galaxy morphologies to real z ~ 1.5 and 4 UV-bright galaxy morphologies. We calculate the Gini coefficient (G), the second-order moment of the brightest 20% of the galaxy's flux (M_20), and the Sersic index (n). We explore the use of nonparametric methods with 2D profile fitting and find the combination of M_20 with n an efficient method to classify galaxies as having merger, exponential disk, or bulge-like morphologies. When classified according to G and M_20, 20/30% of real/simulated galaxies at z ~ 1.5 and 37/12% at z ~ 4 have bulge-like morphologies. The rest have merger-like or intermediate distributions. Alternatively, when classified according to the Se...

  16. Galaxy And Mass Assembly (GAMA): the wavelength dependence of galaxy structure versus redshift and luminosity

    CERN Document Server

    Kennedy, Rebecca; Baldry, Ivan; Holwerda, Boris Häußler Benne W; Hopkins, Andrew M; Kelvin, Lee S; Lange, Rebecca; Moffett, Amanda J; Popescu, Cristina C; Taylor, Edward N; Tuffs, Richard J; Vika, Marina; Vulcani, Benedetta

    2015-01-01

    We study how the sizes and radial profiles of galaxies vary with wavelength, by fitting S\\'ersic functions simultaneously to imaging in nine optical and near-infrared bands. To quantify the wavelength dependence of effective radius we use the ratio, $\\mathcal{R}$, of measurements in two restframe bands. The dependence of S\\'ersic index on wavelength, $\\mathcal{N}$, is computed correspondingly. Vulcani et al. (2014) have demonstrated that different galaxy populations present sharply contrasting behaviour in terms of $\\mathcal{R}$ and $\\mathcal{N}$. Here we study the luminosity dependence of this result. We find that at higher luminosities, early-type galaxies display a more substantial decrease in effective radius with wavelength, whereas late-types present a more pronounced increase in S\\'ersic index. The structural contrast between types thus increases with luminosity. By considering samples at different redshifts, we demonstrate that lower data quality reduces the apparent difference between the main galaxy...

  17. A Photometric redshift galaxy catalog from the Red-Sequence Cluster Survey

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Bau-Ching; /Taiwan, Natl. Central U. /Taipei, Inst. Astron. Astrophys.; Yee, H.K.C.; /Toronto U., Astron. Dept.; Lin, H.; /Fermilab; Gladders, M.D.; /Carnegie Inst.

    2005-02-01

    The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the z' and R{sub c} bands for 90 square degrees of sky, and supplemental V and B data have been obtained for 33.6 deg{sup 2}. They compile a photometric redshift catalog from these 4-band data by utilizing the empirical quadratic polynomial photometric redshift fitting technique in combination with CNOC2 and GOODS/HDF-N redshift data. The training set includes 4924 spectral redshifts. The resulting catalog contains more than one million galaxies with photometric redshifts < 1.5 and R{sub c} < 24, giving an rms scatter {delta}({Delta}z) < 0.06 within the redshift range 0.2 < z < 0.5 and {sigma}({Delta}z) < 0.11 for galaxies at 0.0 < z < 1.5. They describe the empirical quadratic polynomial photometric redshift fitting technique which they use to determine the relation between red-shift and photometry. A kd-tree algorithm is used to divide up the sample to improve the accuracy of the catalog. They also present a method for estimating the photometric redshift error for individual galaxies. They show that the redshift distribution of the sample is in excellent agreement with smaller and much deeper photometric and spectroscopic redshift surveys.

  18. Revealing the nature of star forming blue early-type galaxies at low redshift

    CERN Document Server

    George, Koshy

    2015-01-01

    Context: Star forming early-type galaxies with blue optical colours at low redshift can be used to test our current understanding of galaxy formation and evolution. Aims: We want to reveal the fuel and triggering mechanism for star formation in these otherwise passively evolving red and dead stellar systems. Methods: We undertook an optical and ultraviolet study of 55 star forming blue early-type galaxies, searching for signatures of recent interactions that could be driving the molecular gas into the galaxy and potentially triggering the star formation. Results: We report here our results on star forming blue early-type galaxies with tidal trails and in close proximity to neighbouring galaxies that are evidence of ongoing or recent interactions between galaxies. There are 12 galaxies with close companions with similar redshifts, among which two galaxies are having ongoing interactions that potentially trigger the star formation. Two galaxies show a jet feature that could be due to the complete tidal disrupti...

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

    Energy Technology Data Exchange (ETDEWEB)

    Lapi, A.; Raimundo, S.; Aversa, R.; Cai, Z.-Y.; Celotti, A.; De Zotti, G.; Danese, L. [SISSA, Via Bonomea 265, I-34136 Trieste (Italy); Negrello, M. [INAF-Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy)

    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.

  20. NICMOS observations of high redshift radio galaxies witnessing the formation of bright elliptical galaxies?

    CERN Document Server

    Pentericci, L; Röttgering, H J A; Miley, G K; Van Breugel, W; Fosbury, R A E

    2001-01-01

    We present the results of a near infrared imaging program of a sample of 19 radio galaxies with redshift between 1.7 and 3.2, using the NICMOS Camera 2 on the Hubble Space Telescope. The galaxies were observed in H-band which, for 18 of the 19 targets, samples the rest-frame optical emission longwards of the 4000 A break. The images show a wide range of morphologies, from unresolved to compact systems, to systems with substructures such as multiple emission peaks, to systems comprised of several components spread over large areas. The morphologies of 5 of the lowest redshift targets are well represented by a de Vaucouleurs profile, consistent with them being elliptical galaxies. Their average effective radius is a factor of 2 smaller than that of z=1 3CR radio galaxies at similar restframe wavelengths. The near infrared continuum light is generally well aligned with the radio axis and the aligned light has typical V-H colors of around 3.5-4. For several galaxies where WFPC2 images were available, we computed ...

  1. Relativistic jet feedback in high-redshift galaxies I: Dynamics

    CERN Document Server

    Mukherjee, Dipanjan; Sutherland, Ralph S; Wagner, A Y

    2016-01-01

    We present the results of three dimensional relativistic hydrodynamic simulations of interaction of AGN jets with a dense turbulent two-phase interstellar medium, which would be typical of high redshift galaxies. We describe the effect of the jet on the evolution of the density of the turbulent ISM. The jet driven energy bubble affects the gas to distances up to several kiloparsecs from the injection region. The shocks resulting from such interactions create a multi-phase ISM and radial outflows. One of the striking result of this work is that low power jets (P_jet < 10^{43} erg/s) although less efficient in accelerating clouds, are trapped in the ISM for a longer time and hence affect the ISM over a larger volume. Jets of higher power drill through with relative ease. Although the relativistic jets launch strong outflows, there is little net mass ejection to very large distances, supporting a galactic fountain scenario for local feedback.

  2. Distributions of Quasar Hosts on the Galaxy Main Sequence Plane

    Science.gov (United States)

    Zhang, Zhoujian; Shi, Yong; Rieke, George H.; Xia, Xiaoyang; Wang, Yikang; Sun, Bingqing; Wan, Linfeng

    2016-03-01

    The relation between star formation rates (SFRs) and stellar masses, i.e., the galaxy main sequence, is a useful diagnostic of galaxy evolution. We present the distributions relative to the main sequence of 55 optically selected PG and 12 near-IR-selected Two Micron All Sky Survey (2MASS) quasars at z ≤ 0.5. We estimate the quasar host stellar masses from Hubble Space Telescope or ground-based AO photometry, and the SFRs through the mid-infrared aromatic features and far-IR photometry. We find that PG quasar hosts more or less follow the main sequence defined by normal star-forming galaxies while 2MASS quasar hosts lie systematically above the main sequence. PG and 2MASS quasars with higher nuclear luminosities seem to have higher specific SFRs (sSFRs), although there is a large scatter. No trends are seen between sSFRs and SMBH masses, Eddington ratios, or even morphology types (ellipticals, spirals, and mergers). Our results could be placed in an evolutionary scenario with quasars emerging during the transition from ULIRGs/mergers to ellipticals. However, combined with results at higher redshift, they suggest that quasars can be widely triggered in normal galaxies as long as they contain abundant gas and have ongoing star formation.

  3. The problematic growth of dust in high-redshift galaxies

    Science.gov (United States)

    Ferrara, A.; Viti, S.; Ceccarelli, C.

    2016-11-01

    Dust growth via accretion of gas species has been proposed as the dominant process to increase the amount of dust in galaxies. We show here that this hypothesis encounters severe difficulties that make it unfit to explain the observed UV and IR properties of such systems, particularly at high redshifts. Dust growth in the diffuse ISM phases is hampered by (a) too slow accretion rates, (b) too high dust temperatures, and (c) the Coulomb barrier that effectively blocks accretion. In molecular clouds these problems are largely alleviated. Grains are cold (but not colder than the CMB temperature, TCMB ≈ 20 K at redshift z = 6). However, in dense environments accreted materials form icy water mantles, perhaps with impurities. Mantles are immediately (≲1 yr) photo-desorbed as grains return to the diffuse ISM at the end of the cloud lifetime, thus erasing any memory of the growth. We conclude that dust attenuating stellar light at high-z must be ready-made stardust largely produced in supernova ejecta.

  4. Galaxy growth from redshift 5 to 0 at fixed comoving number density

    CERN Document Server

    van de Voort, Freeke

    2016-01-01

    Studying the average properties of galaxies at a fixed comoving number density over a wide redshift range has become a popular observational method, because it may trace the evolution of galaxies statistically. We test this method by comparing the evolution of galaxies at fixed number density and by following individual galaxies through cosmic time (z=0-5) in cosmological, hydrodynamical simulations from OWLS. Comparing progenitors, descendants, and galaxies selected at fixed number density at each redshift, we find differences of up to a factor of three for galaxy and interstellar medium (ISM) masses. The difference is somewhat larger for black hole masses. The scatter in ISM mass increases significantly towards low redshift with all selection techniques. We use the fixed number density technique to study the assembly of dark matter, gas, stars, and black holes and the evolution in accretion and star formation rates. We find three different regimes for massive galaxies, consistent with observations: at high ...

  5. Redshift of Galaxy Clusters from the Sunyaev-Zel'dovich effect

    CERN Document Server

    Diego-Rodriguez, J M; Silk, J; Bryan, G

    2002-01-01

    We develop a new method for estimating the redshift of galaxy clusters through resolved images of the Sunyaev-Zel'dovich effect (SZE). Our method is based on morphological observables which can be measured by actual and future SZE experiments. The method is tested using a set of high resolution hydrodynamical simulations of galaxy clusters at different redshifts. The method combines the observables in a principal component analysis. We show how this can give an estimate of the redshift of the galaxy clusters. Although the uncertainty in the redshift estimation is large, the method should be useful for future SZE surveys where hundreds of clusters are expected to be detected. A first preselection of the high redshift candidates could be done using our proposed morphological redshift estimator.

  6. Host galaxies of long gamma-ray bursts in the Millennium Simulation

    Science.gov (United States)

    Chisari, N. E.; Tissera, P. B.; Pellizza, L. J.

    2010-10-01

    In this work, we investigate the nature of the host galaxies of long gamma-ray bursts (LGRBs) using a galaxy catalogue constructed from the Millennium Simulation. We developed an LGRB synthetic model based on the hypothesis that these events originate at the end of the life of massive stars following the collapsar model, with the possibility of including a constraint on the metallicity of the progenitor star. A complete observability pipeline was designed to calculate a probability estimation for a galaxy to be observationally identified as a host for LGRBs detected by present observational facilities. This new tool allows us to build an observable host galaxy catalogue which is required to reproduce the current stellar mass distribution of observed hosts. This observability pipeline predicts that the minimum mass for the progenitor stars should be ~ 75 Msolar in order to be able to reproduce BATSE observations. Systems in our observable catalogue are able to reproduce the observed properties of host galaxies, namely stellar masses, colours, luminosity, star formation activity and metallicities as a function of redshift. At z > 2, our model predicts that the observable host galaxies would be very similar to the global galaxy population. We found that ~ 88 per cent of the observable host galaxies with mean gas metallicity lower than 0.6 Zsolar have stellar masses in the range 108.5-1010.3 Msolar, in excellent agreement with observations. Interestingly in our model, observable host galaxies remain mainly within this mass range regardless of redshift, since lower stellar mass systems would have a low probability of being observed while more massive ones would be too metal-rich. Observable host galaxies are predicted to preferentially inhabit dark matter haloes in the range 1011-1011.5 Msolar, with a weak dependence on redshift. They are also found to preferentially map different density environments at different stages of evolution of the Universe. At high redshifts

  7. A distortion of very-high-redshift galaxy number counts by gravitational lensing.

    Science.gov (United States)

    Wyithe, J Stuart B; Yan, Haojing; Windhorst, Rogier A; Mao, Shude

    2011-01-13

    The observed number counts of high-redshift galaxy candidates have been used to build up a statistical description of star-forming activity at redshift z ≳ 7, when galaxies reionized the Universe. Standard models predict that a high incidence of gravitational lensing will probably distort measurements of flux and number of these earliest galaxies. The raw probability of this happening has been estimated to be ∼0.5 per cent (refs 11, 12), but can be larger owing to observational biases. Here we report that gravitational lensing is likely to dominate the observed properties of galaxies with redshifts of z ≳ 12, when the instrumental limiting magnitude is expected to be brighter than the characteristic magnitude of the galaxy sample. The number counts could be modified by an order of magnitude, with most galaxies being part of multiply imaged systems, located less than 1 arcsec from brighter foreground galaxies at z ≈ 2. This lens-induced association of high-redshift and foreground galaxies has perhaps already been observed among a sample of galaxy candidates identified at z ≈ 10.6. Future surveys will need to be designed to account for a significant gravitational lensing bias in high-redshift galaxy samples.

  8. Escape of about five per cent of Lyman-alpha photons from high-redshift star-forming galaxies.

    Science.gov (United States)

    Hayes, Matthew; Ostlin, Göran; Schaerer, Daniel; Mas-Hesse, J Miguel; Leitherer, Claus; Atek, Hakim; Kunth, Daniel; Verhamme, Anne; de Barros, Stéphane; Melinder, Jens

    2010-03-25

    The Lyman-alpha (Lyalpha) emission line is the primary observational signature of star-forming galaxies at the highest redshifts, and has enabled the compilation of large samples of galaxies with which to study cosmic evolution. The resonant nature of the line, however, means that Lyalpha photons scatter in the neutral interstellar medium of their host galaxies, and their sensitivity to absorption by interstellar dust may therefore be greatly enhanced. This implies that the Lyalpha luminosity may be significantly reduced, or even completely suppressed. Hitherto, no unbiased empirical test of the escaping fraction (f(esc)) of Lyalpha photons has been performed at high redshifts. Here we report that the average f(esc) from star-forming galaxies at redshift z = 2.2 is just 5 per cent by performing a blind narrowband survey in Lyalpha and Halpha. This implies that numerous conclusions based on Lyalpha-selected samples will require upwards revision by an order of magnitude and we provide a benchmark for this revision. We demonstrate that almost 90 per cent of star-forming galaxies emit insufficient Lyalpha to be detected by standard selection criteria. Both samples show an anti-correlation of f(esc) with dust content, and we show that Lyalpha- and Halpha-selection recovers populations that differ substantially in dust content and f(esc).

  9. The host galaxy of GRB 990712

    DEFF Research Database (Denmark)

    Christensen, L.; Hjorth, J.; Gorosabel, J.

    2004-01-01

    We present a comprehensive study of the z = 0.43 host galaxy of GRB 990712, involving ground-based photometry, spectroscopy, and HST imaging. The broad-band UBVRIJHKs photometry is used to determine the global spectral energy distribution (SED) of the host galaxy. Comparison with that of known...... galaxy types shows that the host is similar to a moderately kreddened starburst galaxy with a young stellar population. The estimated internal extinction in the host is A(V) = 0.15 +/- 0.1 and the star-formation rate (SFR) from the UV continuum is 1.3 +/- 0.3 M-circle dot yr(-1) (not corrected...... for the effects of extinction). Other galaxy template spectra than starbursts failed to reproduce the observed SED. We also present VLT spectra leading to the detection of Halpha from the GRB host galaxy. A SFR of 2.8 +/- 0.7 M-circle dot yr(-1) is inferred from the Halpha line flux, and the presence of a young...

  10. Keck Observations of 160 Gamma-Ray Burst Host Galaxies

    CERN Document Server

    Perley, Daniel A; Prochaska, Jason X

    2013-01-01

    We present a preliminary data release from our multi-year campaign at Keck Observatory to study the host galaxies of a large sample of Swift-era gamma-ray bursts via multi-color ground-based optical imaging and spectroscopy. With over 160 targets observed to date (and almost 100 host detections, most of which have not previously been reported in the literature) our effort represents the broadest GRB host survey to date. While targeting was heterogeneous, our observations span the known diversity of GRBs including short bursts, long bursts, spectrally soft GRBs (XRFs), ultra-energetic GRBs, X-ray faint GRBs, dark GRBs, SN-GRBs, and other sub-classes. We also present a preview of our database (currently available online via a convenient web interface) including a catalog of multi-color photometry, redshifts and line ID's. Final photometry and reduced imaging and spectra will be available in the near future.

  11. The Coevolution of Supermassive Black Holes and Massive Galaxies at High Redshift

    CERN Document Server

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

    2013-01-01

    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 AGN 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: (i) 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, (ii) 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 into a massive reservoir/proto-torus wherefrom it can be promptly accreted; (iii) the BH grows by accretion in a self-regulated regime with radiative power that can slightly exceed the Eddington...

  12. Molecular Gas in the Halo Fuels the Growth of a Massive Cluster Galaxy at High Redshift

    CERN Document Server

    Emonts, B H C; Villar-Martin, 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; Rottgering, H J A; De Breuck, C; Seymour, N; Gullberg, B; Ceverino, D; Jagannathan, P; Vernet, J; Indermuehle, B T

    2016-01-01

    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 inter-galactic 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.

  13. Galaxy and Mass Assembly (GAMA): Redshift Space Distortions from the Clipped Galaxy Field

    CERN Document Server

    Simpson, Fergus; Peacock, John A; Baldry, Ivan; Bland-Hawthorn, Joss; Heavens, Alan; Heymans, Catherine; Loveday, Jon; Norberg, Peder

    2015-01-01

    We present the first cosmological measurement derived from a galaxy density field subject to a `clipping' transformation. By enforcing an upper bound on the galaxy number density field in the Galaxy and Mass Assembly survey (GAMA), contributions from the nonlinear processes of virialisation and galaxy bias are greatly reduced. This leads to a galaxy power spectrum which is easier to model, without calibration from numerical simulations. We develop a theoretical model for the power spectrum of a clipped field in redshift space, which is exact for the case of anisotropic Gaussian fields. Clipping is found to extend the applicability of the conventional Kaiser prescription by more than a factor of three in wavenumber, or a factor of thirty in terms of the number of Fourier modes. By modelling the galaxy power spectrum on scales k < 0.3 h/Mpc and density fluctuations $\\delta_g < 4$ we measure the normalised growth rate $f\\sigma_8(z = 0.18) = 0.29 \\pm 0.10$.

  14. Photometric redshifts and clustering of emission line galaxies selected jointly by DES and eBOSS

    Energy Technology Data Exchange (ETDEWEB)

    Jouvel, S.; et al.

    2015-09-23

    We present the results of the first test plates of the extended Baryon Oscillation Spectroscopic Survey. This paper focuses on the emission line galaxies (ELG) population targetted from the Dark Energy Survey (DES) photometry. We analyse the success rate, efficiency, redshift distribution, and clustering properties of the targets. From the 9000 spectroscopic redshifts targetted, 4600 have been selected from the DES photometry. The total success rate for redshifts between 0.6 and 1.2 is 71\\% and 68\\% respectively for a bright and faint, on average more distant, samples including redshifts measured from a single strong emission line. We find a mean redshift of 0.8 and 0.87, with 15 and 13\\% of unknown redshifts respectively for the bright and faint samples. In the redshift range 0.6redshifts, the mean redshift for the bright and faint sample is 0.85 and 0.9 respectively. Star contamination is lower than 2\\%. We measure a galaxy bias averaged on scales of 1 and 10~Mpc/h of 1.72 \\pm 0.1 for the bright sample and of 1.78 \\pm 0.12 for the faint sample. The error on the galaxy bias have been obtained propagating the errors in the correlation function to the fitted parameters. This redshift evolution for the galaxy bias is in agreement with theoretical expectations for a galaxy population with MB-5\\log h < -21.0. We note that biasing is derived from the galaxy clustering relative to a model for the mass fluctuations. We investigate the quality of the DES photometric redshifts and find that the outlier fraction can be reduced using a comparison between template fitting and neural network, or using a random forest algorithm.

  15. Tidal Disruption Events Prefer Unusual Host Galaxies

    CERN Document Server

    French, K Decker; Zabludoff, Ann

    2016-01-01

    Tidal Disruption Events (TDEs) are transient events observed when a star passes close enough to a supermassive black hole to be tidally destroyed. Many TDE candidates have been discovered in host galaxies whose spectra have weak or no line emission yet strong Balmer line absorption, indicating a period of intense star formation that has recently ended. As such, TDE host galaxies fall into the rare class of quiescent Balmer-strong galaxies. Here, we quantify the fraction of galaxies in the Sloan Digital Sky Survey (SDSS) with spectral properties like those of TDE hosts, determining the extent to which TDEs are over-represented in such galaxies. Galaxies whose spectra have Balmer absorption H$\\delta_{\\rm A}$ $-$ $\\sigma$(H$\\delta_{\\rm A}$) $>$ 4 \\AA\\ (where $\\sigma$(H$\\delta_{\\rm A}$) is the error in the Lick H$\\delta_{\\rm A}$ index) and H$\\alpha$ emission EW $$ 1.31 \\AA\\ and H$\\alpha$ EW $80\\times$ enhancement in such hosts and providing an observational link between the $\\gamma$/X-ray-bright and optical/UV-br...

  16. Complete Ionisation of the Neutral Gas in High Redshift Radio Galaxies and Quasars

    CERN Document Server

    Curran, S J

    2012-01-01

    Cool neutral gas provides the raw material for all star formation in the Universe, and yet, from a survey of the hosts of high redshift radio galaxies and quasars, we find a complete dearth of atomic (HI 21-cm) and molecular (OH, CO, HCO+ & HCN) absorption at redshifts z > 3. Upon a thorough analysis of the optical photometry, we find that all of our targets have ionising ultra-violet continuum luminosities of logL > 23 W/Hz. We therefore attribute this deficit to the traditional optical selection of targets biasing surveys towards the most ultra-violet luminous objects, where the intense radiation excites the neutral gas to the point where it cannot engage in star formation. However, this hypothesis does not explain why there is a critical luminosity, rather than a continuum where the detections gradually become fewer and fewer as the harshness of the radiation increases. We show that by placing a quasar within a galaxy of gas there is always a finite ultra-violet luminosity above which all of the gas is...

  17. Frequency and properties of bars in cluster and field galaxies at intermediate redshifts

    CERN Document Server

    Barazza, Fabio D; Desai, Vandana; Jogee, Shardha; Aragon-Salamanca, Alfonso; De Lucia, Gabriella; Saglia, Roberto P; Halliday, Claire; Poggianti, Bianca M; Dalcanton, Julianne J; Rudnick, Gregory; Milvang-Jensen, Bo; Noll, Stefan; Simard, Luc; Clowe, Douglas I; Pello, Roser; White, Simon D M; Zaritsky, Dennis

    2009-01-01

    We present a study of large-scale bars in field and cluster environments out to redshifts of ~0.8 using a final sample of 945 moderately inclined disk galaxies drawn from the EDisCS project. We characterize bars and their host galaxies and look for relations between the presence of a bar and the properties of the underlying disk. We investigate whether the fraction and properties of bars in clusters are different from their counterparts in the field. The total optical bar fraction in the redshift range z=0.4-0.8 (median z=0.60), averaged over the entire sample, is 25% (20% for strong bars). For the cluster and field subsamples, we measure bar fractions of 24% and 29%, respectively. We find that bars in clusters are on average longer than in the field and preferentially found close to the cluster center, where the bar fraction is somewhat higher (~31%) than at larger distances (~18%). These findings however rely on a relatively small subsample and might be affected by small number statistics. In agreement with...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  19. The host galaxy and environment of a neutron star merger

    CERN Document Server

    Postigo, A de Ugarte; Rowlinson, A; Garcia-Benito, R; Levan, A J; Gorosabel, J; Goldoni, P; Schulze, S; Zafar, T; Wiersema, K; Sanchez-Ramirez, R; Melandri, A; D'Avanzo, P; Oates, S; D'Elia, V; De Pasquale, M; Kruehler, T; van der Horst, A J; Xu, D; Watson, D; Piranomonte, S; Vergani, S; Milvang-Jensen, B; Kaper, L; Malesani, D; Fynbo, J P U; Cano, Z; Covino, S; Flores, H; Greiss, S; Hammer, F; Hartoog, O E; Hellmich, S; Heuser, C; Hjorth, J; Jakobsson, P; Mottola, S; Sparre, M; Sollerman, J; Tagliaferri, G; Tanvir, N R; Vestergaard, M; Wijers, R A M J

    2013-01-01

    The mergers of neutron stars have been predicted to cause an r-process supernova - a luminous near-infrared transient powered by the radioactive decay of freshly formed heavy metals. An r-process supernova, or kilonova, has recently been discovered coincident with the short-duration gamma-ray burst GRB 130603B, simultaneously confirming the widely-held theory of the origin of most short-durations GRBs in neutron star mergers. We report here the absorption spectrum of the afterglow of this GRB. From it we determine the redshift of the burst and the properties of the host galaxy and the environment in which the merger occurred. The merger is not associated with the most star-forming region of the galaxy; however, it did occur in a dense region, implying a rapid merger or a low natal kick velocity for the neutron star binary.

  20. Detailed afterglow modelling and host galaxy properties of the dark GRB 111215A

    DEFF Research Database (Denmark)

    Horst, A. J. van der; Levan, A. J.; Pooley, G. G.

    2015-01-01

    bursts for which similar modeling work has been performed. We also present deep imaging of the host galaxy with the Keck I telescope, Spitzer Space Telescope, and Hubble Space Telescope (HST), which resulted in a well-constrained photometric redshift, giving credence to the tentative spectroscopic...

  1. THE DEEP2 GALAXY REDSHIFT SURVEY: THE VORONOI-DELAUNAY METHOD CATALOG OF GALAXY GROUPS

    Energy Technology Data Exchange (ETDEWEB)

    Gerke, Brian F. [KIPAC, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, MS 29, Menlo Park, CA 94725 (United States); Newman, Jeffrey A. [Department of Physics and Astronomy, 3941 O' Hara Street, Pittsburgh, PA 15260 (United States); Davis, Marc [Department of Physics and Department of Astronomy, Campbell Hall, University of California-Berkeley, Berkeley, CA 94720 (United States); Coil, Alison L. [Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, MC 0424, La Jolla, CA 92093 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California-Irvine, Irvine, CA 92697 (United States); Dutton, Aaron A. [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 5C2 (Canada); Faber, S. M.; Guhathakurta, Puragra; Koo, David C.; Phillips, Andrew C. [UCO/Lick Observatory, University of California-Santa Cruz, Santa Cruz, CA 95064 (United States); Konidaris, Nicholas; Lin, Lihwai [Astronomy Department, Caltech 249-17, Pasadena, CA 91125 (United States); Noeske, Kai [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Rosario, David J. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching bei Muenchen (Germany); Weiner, Benjamin J.; Willmer, Christopher N. A. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Yan, Renbin [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

    2012-05-20

    We present a public catalog of galaxy groups constructed from the spectroscopic sample of galaxies in the fourth data release from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Galaxy Redshift Survey, including the Extended Groth Strip (EGS). The catalog contains 1165 groups with two or more members in the EGS over the redshift range 0 < z < 1.5 and 1295 groups at z > 0.6 in the rest of DEEP2. Twenty-five percent of EGS galaxies and fourteen percent of high-z DEEP2 galaxies are assigned to galaxy groups. The groups were detected using the Voronoi-Delaunay method (VDM) after it has been optimized on mock DEEP2 catalogs following similar methods to those employed in Gerke et al. In the optimization effort, we have taken particular care to ensure that the mock catalogs resemble the data as closely as possible, and we have fine-tuned our methods separately on mocks constructed for the EGS and the rest of DEEP2. We have also probed the effect of the assumed cosmology on our inferred group-finding efficiency by performing our optimization on three different mock catalogs with different background cosmologies, finding large differences in the group-finding success we can achieve for these different mocks. Using the mock catalog whose background cosmology is most consistent with current data, we estimate that the DEEP2 group catalog is 72% complete and 61% pure (74% and 67% for the EGS) and that the group finder correctly classifies 70% of galaxies that truly belong to groups, with an additional 46% of interloper galaxies contaminating the catalog (66% and 43% for the EGS). We also confirm that the VDM catalog reconstructs the abundance of galaxy groups with velocity dispersions above {approx}300 km s{sup -1} to an accuracy better than the sample variance, and this successful reconstruction is not strongly dependent on cosmology. This makes the DEEP2 group catalog a promising probe of the growth of cosmic structure that can potentially be used for cosmological tests.

  2. A Dust-Obscured Massive Maximum-Starburst Galaxy at a Redshift of 6.34

    CERN Document Server

    Riechers, Dominik A; Clements, D L; Dowell, C D; Perez-Fournon, I; Ivison, R J; Bridge, C; Conley, A; Fu, Hai; Vieira, J D; Wardlow, J; Calanog, J; Cooray, A; Hurley, P; Neri, R; Kamenetzky, J; Aguirre, J E; Altieri, B; Arumugam, V; Benford, D J; Bethermin, M; Bock, J; Burgarella, D; Cabrera-Lavers, A; Chapman, S C; Cox, P; Dunlop, J S; Earle, L; Farrah, D; Ferrero, P; Franceschini, A; Gavazzi, R; Glenn, J; Solares, E A Gonzalez; Gurwell, M A; Halpern, M; Hatziminaoglou, E; Hyde, A; Ibar, E; Kovacs, A; Krips, M; Lupu, R E; Maloney, P R; Martinez-Navajas, P; Matsuhara, H; Murphy, E J; Naylor, B J; Nguyen, H T; Oliver, S J; Omont, A; Page, M J; Petitpas, G; Rangwala, N; Roseboom, I G; Scott, D; Smith, A J; Staguhn, J G; Streblyanska, A; Thomson, A P; Valtchanov, I; Viero, M; Wang, L; Zemcov, M; Zmuidzinas, J

    2013-01-01

    Massive present-day early-type (elliptical and lenticular) galaxies probably gained the bulk of their stellar mass and heavy elements through intense, dust-enshrouded starbursts - that is, increased rates of star formation - in the most massive dark matter halos at early epochs. However, it remains unknown how soon after the Big Bang such massive starburst progenitors exist. The measured redshift distribution of dusty, massive starbursts has long been suspected to be biased low in redshift owing to selection effects, as confirmed by recent findings of systems out to redshift z~5. Here we report the identification of a massive starburst galaxy at redshift 6.34 through a submillimeter color-selection technique. We unambiguously determined the redshift from a suite of molecular and atomic fine structure cooling lines. These measurements reveal a hundred billion solar masses of highly excited, chemically evolved interstellar medium in this galaxy, which constitutes at least 40% of the baryonic mass. A "maximum st...

  3. Possible Local Spiral Counterparts to Compact Blue Galaxies at Intermediate Redshift

    CERN Document Server

    Barton, E J; Barton, Elizabeth J.; Zee, Liese van

    2001-01-01

    We identify nearby disk galaxies with optical structural parameters similar to those of intermediate-redshift compact blue galaxies. By comparing HI and optical emission-line widths, we show that the optical widths substantially underestimate the true kinematic widths of the local galaxies. By analogy, optical emission-line widths may underrepresent the masses of intermediate-z compact objects. For the nearby galaxies, the compact blue morphology is the result of tidally-triggered central star formation: we argue that interactions and minor mergers may cause apparently compact morphology at higher redshift.

  4. The Dwarf Starburst Host Galaxy of a Type Ia SN at z = 1.55 from CANDELS

    CERN Document Server

    Frederiksen, Teddy F; Maund, Justyn R; Rodney, Steven A; Riess, Adam G; Dahlen, Tomas; Mobasher, Bahram

    2012-01-01

    We present VLT/X-shooter observations of a high redshift, type Ia supernova host galaxy, discovered with HST/WFC3 as part of the CANDELS Supernova project. The galaxy exhibits strong emission lines of Ly{\\alpha}, [O II], H{\\beta}, [O III], and H{\\alpha} at z = 1.54992(+0.00008-0.00004). From the emission-line fluxes and SED fitting of broad-band photometry we rule out AGN activity and characterize the host galaxy as a young, low mass, metal poor, starburst galaxy with low intrinsic extinction and high Ly{\\alpha} escape fraction. The host galaxy stands out in terms of the star formation, stellar mass, and metallicity compared to its lower redshift counterparts, mainly because of its high specific star-formation rate. If valid for a larger sample of high-redshift SN Ia host galaxies, such changes in the host galaxy properties with redshift are of interest because of the potential impact on the use of SN Ia as standard candles in cosmology.

  5. Spectroscopy of superluminous supernova host galaxies

    DEFF Research Database (Denmark)

    Leloudas, G.; Kruehler, T.; Schulze, S

    2015-01-01

    Superluminous supernovae (SLSNe) are very bright explosions that were only discovered recently and that show a preference for occurring in faint dwarf galaxies. Understanding why stellar evolution yields different types of stellar explosions in these environments is fundamental in order to both...... uncover the elusive progenitors of SLSNe and to study star formation in dwarf galaxies. In this paper, we present the first results of our project to study SUperluminous Supernova Host galaxIES, focusing on the sample for which we have obtained spectroscopy. We show that SLSNe-I and SLSNe-R (hydrogen...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-05-03

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

  7. Dark-ages reionization & galaxy formation simulation IV: UV luminosity functions of high-redshift galaxies

    CERN Document Server

    Liu, Chuanwu; Angel, P W; Duffy, Alan R; Geil, Paul M; Poole, Gregory B; Mesinger, Andrei; Wyithe, J Stuart B

    2015-01-01

    In this paper we present calculations of the UV luminosity function predictions from the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulations (DRAGONS) project, which combines N-body, semi-analytic and semi-numerical modeling designed to study galaxy formation during the Epoch of Reionization. Using galaxy formation physics including supernova feedback, the model naturally reproduces the UV LFs for high-redshift star-forming galaxies from $z{\\sim}5$ through to $z{\\sim}10$. We investigate the predicted luminosity-star formation rate (SFR) relation, finding that variable SFR histories of galaxies result in a scatter around the mean relation of $0.1$-$0.3$ dex depending on UV luminosity. We find close agreement between the model and observationally derived SFR functions. We use our predicted luminosities to investigate the luminosity function below current detection limits, and the ionizing photon budget for reionization. We predict that the slope of the UV LF remains steep below cu...

  8. Galaxy growth from redshift 5 to 0 at fixed comoving number density

    Science.gov (United States)

    van de Voort, Freeke

    2016-10-01

    Studying the average properties of galaxies at a fixed comoving number density over a wide redshift range has become a popular observational method, because it may trace the evolution of galaxies statistically. We test this method by comparing the evolution of galaxies at fixed number density and by following individual galaxies through cosmic time (z = 0-5) in cosmological, hydrodynamical simulations from the OverWhelmingly Large Simulations project. Comparing progenitors, descendants, and galaxies selected at fixed number density at each redshift, we find differences of up to a factor of 3 for galaxy and interstellar medium (ISM) masses. The difference is somewhat larger for black hole masses. The scatter in ISM mass increases significantly towards low redshift with all selection techniques. We use the fixed number density technique to study the assembly of dark matter, gas, stars, and black holes and the evolution in accretion and star formation rates. We find three different regimes for massive galaxies, consistent with observations: at high redshift the gas accretion rate dominates, at intermediate redshifts the star formation rate is the highest, and at low redshift galaxies grow mostly through mergers. Quiescent galaxies have much lower ISM masses (by definition) and much higher black hole masses, but the stellar and halo masses are fairly similar. Without active galactic nucleus (AGN) feedback, massive galaxies are dominated by star formation down to z = 0 and most of their stellar mass growth occurs in the centre. With AGN feedback, stellar mass is only added to the outskirts of galaxies by mergers and they grow inside-out.

  9. Line-emitting galaxies beyond a redshift of 7: an improved method for estimating the evolving neutrality of the intergalactic medium

    Energy Technology Data Exchange (ETDEWEB)

    Schenker, Matthew A.; Ellis, Richard S.; Konidaris, Nick P. [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Stark, Daniel P., E-mail: schenker@astro.caltech.edu [Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2014-11-01

    The redshift-dependent fraction of color-selected galaxies revealing Lyman alpha (Lyα) emission, x {sub Lyα} has become the most valuable constraint on the evolving neutrality of the early intergalactic medium. However, in addition to resonant scattering by neutral gas, the visibility of Lyα is also dependent on the intrinsic properties of the host galaxy, including its stellar population, dust content, and the nature of outflowing gas. Taking advantage of significant progress we have made in determining the line-emitting properties of z ≅ 4-6 galaxies, we propose an improved method, based on using the measured slopes of the rest-frame ultraviolet continua of galaxies, to interpret the growing body of near-infrared spectra of z > 7 galaxies in order to take into account these host galaxy dependencies. In a first application of our new method, we demonstrate its potential via a new spectroscopic survey of 7 < z < 8 galaxies undertaken with the Keck MOSFIRE spectrograph. Together with earlier published data, our data provide improved estimates of the evolving visibility of Lyα, particularly at redshift z ≅ 8. As a by-product, we also present a promising new line-emitting galaxy candidate, detected at 4.0σ at redshift z = 7.62. We discuss the improving constraints on the evolving neutral fraction over 6 < z < 8 and the implications for cosmic reionization.

  10. Herschel Extreme Lensing Line Observations: [CII] Variations in Galaxies at Redshifts z=1–3

    Science.gov (United States)

    Malhotra, Sangeeta; Rhoads, James E.; Finkelstein, K.; Yang, Huan; Carilli, Chris; Combes, Françoise; Dassas, Karine; Finkelstein, Steven; Frye, Brenda; Gerin, Maryvonne; Guillard, Pierre; Nesvadba, Nicole; Rigby, Jane; Shin, Min-Su; Spaans, Marco; Strauss, Michael A.; Papovich, Casey

    2017-01-01

    We observed the [C ii] line in 15 lensed galaxies at redshifts 1 HELLO sample is similar to the values seen for low-redshift galaxies, indicating that small grains and PAHs dominate the heating in the neutral ISM, although some of the high [CII]/FIR ratios may be due to turbulent heating. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  11. In Search of Quasar Host Galaxies

    Science.gov (United States)

    Young, Jason; Eracleous, M.; Gronwall, C.; Shemmer, O.; Netzer, H.; Sturm, E.; Ciardullo, R.

    2011-01-01

    We present a study of the morphology and intensity of star formation in the host galaxies of eight Palomar-Green quasars using observations with the Hubble Space Telescope. Accretion-powered and star formation activity have been shown to coincide, motivating us to search for the star-forming regions in the host galaxies of quasars and to determine the star-formation rates. In this work we use calibrated narrow band emission line (H-beta and Pa-alpha) WFPC2 and NICMOS images as maps for total star formation rate. The main challenge in imaging quasar host galaxies is the separation of the quasar light from the galaxy light, especially in the case of z approximately 0.1 quasars in WFPC2 images where the PSF radius closely matches the expected host scale radius. To this this end we present a novel technique for image decomposition and subtraction of quasar light, which we have validated through extensive simulations using artificial quasar+galaxy images. The other significant challenge in mapping and measuring star forming regions is correcting for extinction, which we address using extinction maps created from the Pa-alpha/H-beta ratio. To determine the source of excitation, we utilize H-beta along with [OIII]5007 and [OII]3727 images in diagnostic line ratio (BPT) diagrams. We detect extended line emission in our targets on scales of order 1-2 kpc. A preliminary analysis suggests star formation rates of order 10 solar masses per year.

  12. Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium

    CERN Document Server

    Schenker, Matthew A; Konidaris, Nick P; Stark, Daniel P

    2014-01-01

    The redshift-dependent fraction of color-selected galaxies revealing Lyman alpha emission has become the most valuable constraint on the evolving neutrality of the early intergalactic medium. However, in addition to resonant scattering by neutral gas, the visibility of Lyman alpha is also dependent on the intrinsic properties of the host galaxy, including its stellar population, dust content and the nature of outflowing gas. Taking advantage of significant progress we have made in determining the line emitting properties of $z \\simeq 4-6$ galaxies, we propose an improved method, based on using the measured slopes of the rest-frame ultraviolet continua of galaxies, to interpret the growing body of near-infrared spectra of $z>7$ galaxies in order to take into account these host galaxy dependencies. In a first application of our new method, we demonstrate its potential via a new spectroscopic survey of $7galaxies undertaken with the Keck MOSFIRE spectrograph. Together with earlier published data our ...

  13. Constraining omega from X-ray properties of clusters of galaxies at high redshifts

    DEFF Research Database (Denmark)

    Sadat, R.; Blanchard, A.; Oukbir, J.

    1997-01-01

    Properties of high redshift clusters are a fundamental source of information for cosmology. It has been shown by Oukbir and Blanchard (1997) that the combined knowledge of the redshift distribution of X-ray clusters of galaxies and the luminosity-temperature correlation, L-X - T-X, provides a pow...

  14. The K Band Luminosity Functions of Galaxies in High Redshift Clusters

    CERN Document Server

    Ellis, S C

    2004-01-01

    K band luminosity functions (LFs) of three, massive, high redshift clusters of galaxies are presented. The evolution of K*, the characteristic magnitude of the LF, is consistent with purely passive evolution, and a redshift of forma tion z = 1.5-2.

  15. A short gamma-ray burst apparently associated with an elliptical galaxy at redshift z = 0.225.

    Science.gov (United States)

    Gehrels, N; Sarazin, C L; O'Brien, P T; Zhang, B; Barbier, L; Barthelmy, S D; Blustin, A; Burrows, D N; Cannizzo, J; Cummings, J R; Goad, M; Holland, S T; Hurkett, C P; Kennea, J A; Levan, A; Markwardt, C B; Mason, K O; Meszaros, P; Page, M; Palmer, D M; Rol, E; Sakamoto, T; Willingale, R; Angelini, L; Beardmore, A; Boyd, P T; Breeveld, A; Campana, S; Chester, M M; Chincarini, G; Cominsky, L R; Cusumano, G; de Pasquale, M; Fenimore, E E; Giommi, P; Gronwall, C; Grupe, D; Hill, J E; Hinshaw, D; Hjorth, J; Hullinger, D; Hurley, K C; Klose, S; Kobayashi, S; Kouveliotou, C; Krimm, H A; Mangano, V; Marshall, F E; McGowan, K; Moretti, A; Mushotzky, R F; Nakazawa, K; Norris, J P; Nousek, J A; Osborne, J P; Page, K; Parsons, A M; Patel, S; Perri, M; Poole, T; Romano, P; Roming, P W A; Rosen, S; Sato, G; Schady, P; Smale, A P; Sollerman, J; Starling, R; Still, M; Suzuki, M; Tagliaferri, G; Takahashi, T; Tashiro, M; Tueller, J; Wells, A A; White, N E; Wijers, R A M J

    2005-10-06

    Gamma-ray bursts (GRBs) come in two classes: long (> 2 s), soft-spectrum bursts and short, hard events. Most progress has been made on understanding the long GRBs, which are typically observed at high redshift (z approximately 1) and found in subluminous star-forming host galaxies. They are likely to be produced in core-collapse explosions of massive stars. In contrast, no short GRB had been accurately (sky is near a luminous, non-star-forming elliptical galaxy at a redshift of 0.225, which is the location one would expect if the origin of this GRB is through the merger of neutron-star or black-hole binaries. The X-ray afterglow was weak and faded below the detection limit within a few hours; no optical afterglow was detected to stringent limits, explaining the past difficulty in localizing short GRBs.

  16. Herschel Observed Stripe 82 Quasars and Their Host Galaxies: Connections between AGN Activity and host Galaxy Star Formation

    Science.gov (United States)

    Dong, X. Y.; Wu, Xue-Bing

    2016-06-01

    In this work, we present a study of 207 quasars selected from the Sloan Digital Sky Survey quasar catalogs and the Herschel Stripe 82 survey. Quasars within this sample are high-luminosity quasars with a mean bolometric luminosity of 1046.4 erg s-1. The redshift range of this sample is within z luminosity, far-IR (FIR) luminosity, stellar mass, as well as many other AGN and galaxy properties are deduced from the SED fitting results. The mean star formation rate (SFR) of the sample is 419 M ⊙ yr-1 and the mean gas mass is ˜1011.3 M ⊙. All of these results point to an IR luminous quasar system. Compared with star formation main sequence (MS) galaxies, at least 80 out of 207 quasars are hosted by starburst galaxies. This supports the statement that luminous AGNs are more likely to be associated with major mergers. The SFR increases with the redshift up to z = 2. It is correlated with the AGN bolometric luminosity, where {L}{{FIR}}\\propto {L}{{Bol}}0.46+/- 0.03. The AGN bolometric luminosity is also correlated with the host galaxy mass and gas mass. Yet the correlation between L FIR and L Bol has higher significant level, implies that the link between AGN accretion and the SFR is more primal. The M BH/M * ratio of our sample is 0.02, higher than the value 0.005 in the local universe. It might indicate an evolutionary trend of the M BH-M * scaling relation.

  17. Dark-ages reionization and galaxy-formation simulation - VII. The sizes of high-redshift galaxies

    Science.gov (United States)

    Liu, Chuanwu; Mutch, Simon J.; Poole, Gregory B.; Angel, P. W.; Duffy, Alan R.; Geil, Paul M.; Mesinger, Andrei; Wyithe, J. Stuart B.

    2017-03-01

    We investigate high-redshift galaxy sizes using a semi-analytic model constructed for the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulation project. Our fiducial model, including strong feedback from supernovae and photoionization background, accurately reproduces the evolution of the stellar mass function and ultraviolet (UV) luminosity function. Using this model, we study the size-luminosity relation of galaxies and find that the effective radius scales with UV luminosity as Re ∝ L0.25 at z ∼ 5-9. We show that recently discovered very luminous galaxies at z ∼ 7 and 11 lie on our predicted size-luminosity relations. We find that a significant fraction of galaxies at z > 8 will not be resolved by James Webb Space Telescope, but Giant Magellan Telescope will have the ability to resolve all galaxies in haloes above the atomic cooling limit. We show that our fiducial model successfully reproduces the redshift evolution of average galaxy sizes at z > 5. We also explore galaxy sizes in models without supernova feedback. The no-supernova feedback models produce galaxy sizes that are smaller than observations. We therefore confirm that supernova feedback plays an important role in determining the size-luminosity relation of galaxies and its redshift evolution during reionization.

  18. The Age-Redshift Relationship of Old Passive Galaxies

    CERN Document Server

    Wei, Jun-Jie; Melia, Fulvio; Wang, Fa-Yin; Yu, Hai

    2015-01-01

    We use 32 age measurements of passively evolving galaxies as a function of redshift to test and compare the standard model ($\\Lambda$CDM) with the $R_{\\rm h}=ct$ Universe. We show that the latter fits the data with a reduced $\\chi^2_{\\rm dof}=0.435$ for a Hubble constant $H_{0}= 67.2_{-4.0}^{+4.5}$ km $\\rm s^{-1}$ $\\rm Mpc^{-1}$. By comparison, the optimal flat $\\Lambda$CDM model, with two free parameters (including $\\Omega_{\\rm m}=0.12_{-0.11}^{+0.54}$ and $H_{0}=94.3_{-35.8}^{+32.7}$ km $\\rm s^{-1}$ $\\rm Mpc^{-1}$), fits the age-\\emph{z} data with a reduced $\\chi^2_{\\rm dof}=0.428$. Based solely on their $\\chi^2_{\\rm dof}$ values, both models appear to account for the data very well, though the optimized $\\Lambda$CDM parameters are only marginally consistent with those of the concordance model ($\\Omega_{\\rm m}=0.27$ and $H_{0}= 70$ km $\\rm s^{-1}$ $\\rm Mpc^{-1}$). Fitting the age-$z$ data with the latter results in a reduced $\\chi^2_{\\rm dof}=0.523$. However, because of the different number of free paramete...

  19. The dust budget crisis in high-redshift submillimetre galaxies

    CERN Document Server

    Rowlands, K; Dunne, L; Aragón-Salamanca, A; Dye, S; Maddox, S; da Cunha, E; van der Werf, P

    2014-01-01

    We apply a chemical evolution model to investigate the sources and evolution of dust in a sample of 26 high-redshift ($z>1$) submillimetre galaxies (SMGs) from the literature, with complete photometry from ultraviolet to the submillimetre. We show that dust produced only by low-intermediate mass stars falls a factor 240 short of the observed dust masses of SMGs, the well-known `dust-budget crisis'. Adding an extra source of dust from supernovae can account for the dust mass in 19 per cent of the SMG sample. Even after accounting for dust produced by supernovae the remaining deficit in the dust mass budget provides support for higher supernova yields, substantial grain growth in the interstellar medium or a top-heavy IMF. Including efficient destruction of dust by supernova shocks increases the tension between our model and observed SMG dust masses. The models which best reproduce the physical properties of SMGs have a rapid build-up of dust from both stellar and interstellar sources and minimal dust destructi...

  20. Were progenitors of local L* galaxies Lyman-alpha emitters at high redshift?

    CERN Document Server

    Yajima, Hidenobu; Zhu, Qirong; Abel, Tom; Gronwall, Caryl; Ciardullo, Robin

    2011-01-01

    The Lya emission has been observed from galaxies over a redshift span z ~ 0 - 8.6. However, the link between high-redshift Lya emitters (LAEs) and local galaxies is largely unknown. Here, we investigate the Lya properties of progenitors of a local L^{*} galaxy by combining cosmological hydrodynamic simulations with three-dimensional radiative transfer calculations using the new ART^2 code. We find that the modeled galaxies are Lya bright in redshift z= 0 - 10. In particular, the Lya luminosities of some massive progenitors at z ~ 2 - 6 are close to the observed characteristic L_{Lya}^{*} of LAEs in that redshift range. Both Lya photon escape fraction and line equivalent width increase with redshift. The Lya escape fraction correlates with a number of physical properties of the galaxy, such as mass, SFR and metallicity. We find a "viewing-angle scatter" in which the photon escape depends strongly on the galaxy morphology and orientation. Moreover, we find that high-redshift LAEs show blue-shifted Lya line prof...

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

    CERN Document Server

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

    2008-01-01

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

  2. An analytic halo approach to the bispectrum of galaxies in redshift space

    CERN Document Server

    Yamamoto, Kazuhiro; Hikage, Chiaki

    2016-01-01

    We present an analytic formula for the galaxy bispectrum in redshift space on the basis of the halo approach description with the halo occupation distribution of central galaxies and satellite galaxies. This work is an extension of a previous work on the galaxy power spectrum, which illuminated the significant contribution of satellite galaxies to the higher multipole spectrum through the non-linear redshift space distortions of their random motions. Behaviors of the multipoles of the bispectrum are compared with results of numerical simulations assuming a halo occupation distribution of the LOWZ sample of the SDSS-III BOSS survey. Also presented are analytic approximate formulas for the multipoles of the bispectrum, which is useful to understanding their characteristic properties. We demonstrate that the Fingers of God effect is quite important for the higher multipoles of the bispectrum in redshift space, depending on the halo occupation distribution parameters.

  3. Measurement of Redshift Space Power Spectrum for BOSS galaxies and the Growth Rate at redshift 0.57

    CERN Document Server

    Li, Zhigang; Zhang, Pengjie; Cheng, Dalong

    2016-01-01

    We present a measurement of two-dimensional (2D) redshift-space power spectrum for the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 11 CMASS galaxies in the North Galactic Cap (NGC) based on the method developed by Jing & Borner (2001). In this method, we first measure the 2D redshift-space correlation function for the CMASS galaxies, and obtain the 2D power spectrum based on Fourier Transform of the correlation function. The method is tested with an N-body mock galaxy catalog, which demonstrates that the method can yield an accurate and unbiased measurement of the redshift-space power spectrum given the input 2D correlation function is correct. Compared with previous measurements in literature that are usually based on direct Fourier Transform in redshift space, our method has the advantages that the window function and shot-noise are fully corrected. In fact, our 2D power spectrum, by its construction, can accurately reproduce the 2D correlation function, and in the meanwhile can reproduc...

  4. The Type Ia Supernova Rate in Redshift 0.5-0.9 Galaxy Clusters

    Science.gov (United States)

    Sharon, Keren; Gal-Yam, Avishay; Maoz, Dan; Filippenko, Alexei V.; Foley, Ryan J.; Silverman, Jeffrey M.; Ebeling, Harald; Ma, Cheng-Jiun; Ofek, Eran O.; Kneib, Jean-Paul; Donahue, Megan; Ellis, Richard S.; Freedman, Wendy L.; Kirshner, Robert P.; Mulchaey, John S.; Sarajedini, Vicki L.; Voit, G. Mark

    2010-08-01

    Supernova (SN) rates are potentially powerful diagnostics of metal enrichment and SN physics, particularly in galaxy clusters with their deep, metal-retaining potentials and relatively simple star formation histories. We have carried out a survey for SNe in galaxy clusters, at a redshift range of 0.5 background and foreground events. Keck spectra of the host galaxies were obtained to establish cluster membership. We conducted detailed efficiency simulations, and measured the stellar luminosities of the clusters using Subaru images. We derive a cluster SN rate of 0.35SNu B +0.17 -0.12(statistical) ±0.13(classification) ±0.01(systematic) (where SNu B = SNe (100 yr 1010 L B,sun)-1) and 0.112SNu M +0.055 -0.039(statistical) ±0.042(classification) ±0.005(systematic) (where SNu M = SNe (100 yr 1010 M sun)-1). As in previous measurements of cluster SN rates, the uncertainties are dominated by small-number statistics. The SN rate in this redshift bin is consistent with the SN rate in clusters at lower redshifts (to within the uncertainties), and shows that there is, at most, only a slight increase of cluster SN rate with increasing redshift. The low and fairly constant SN Ia rate out to z ≈ 1 implies that the bulk of the iron mass in clusters was already in place by z ≈ 1. The recently observed doubling of iron abundances in the intracluster medium between z = 1 and 0, if real, is likely to be the result of redistribution of existing iron, rather than new production of iron. 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-10493 and GO-10793, and with archival programs GO-9033, GO-9090, GO-9290, GO-9292, GO-9722, GO-9744, GO-9836, and GO-10509. Based in part on data collected at the Subaru telescope, which is operated by the

  5. The Host Galaxies of Type Ia Supernovae Discovered by the Palomar Transient Factory

    Science.gov (United States)

    Pan, Y.-C.; Sullivan, M.; McGuire, K.; Hook, I. M.; Nugent, P. E.; Howell, D. A.; Arcavi, I.; Botyanszki, J.; Cenko, Stephen Bradley; DeRose, J.

    2013-01-01

    We present spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). We determine star-formation rates, gas-phase stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age mass metallicity are found: fainter, faster-declining events tend to be hosted by older massive metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher-mass metallicity galaxies also appear brighter after stretch colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also compared the host stellar mass distribution to that in galaxy targeted SN surveys and the high-redshift untargeted Supernova Legacy Survey (SNLS). SNLS has many more low mass galaxies, while the targeted searches have fewer. This can be explained by an evolution in the galaxy stellar mass function, coupled with a SN delay-time distribution proportional to t1. Finally, we found no significant difference in the mass--metallicity relation of our SN Ia hosts compared to field galaxies, suggesting any metallicity effect on the SN Ia rate is small.

  6. Host Galaxies of Gamma-Ray Bursts and their Cosmological Evolution

    CERN Document Server

    Courty, S; Gudmundsson, E H

    2004-01-01

    We use numerical simulations of large scale structure formation to explore the cosmological properties of Gamma-Ray Burst (GRB) host galaxies. Among the different sub-populations found in the simulations, we identify the host galaxies as the most efficient star-forming objects, i.e. galaxies with high specific star formation rates. We find that the host candidates are low-mass, young galaxies with low to moderate star formation rate. These properties are consistent with those observed in GRB hosts, most of which are sub-luminous, blue galaxies. Assuming that host candidates are galaxies with high star formation rates would have given conclusions inconsistent with the observations. The specific star formation rate, given a galaxy mass, is shown to increase as the redshift increases. The low mass of the putative hosts makes them difficult to detect with present day telescopes and the probability density function of the specific star formation rate is predicted to change depending on whether or not these galaxie...

  7. The Spitzer/Swift Gamma-Ray Burst Host Galaxy Legacy Survey

    Science.gov (United States)

    Perley, Daniel; Berger, Edo; Butler, Nathaniel; Cenko, S. Bradley; Chary, Ranga-Ram; Cucchiara, Antonino; Ellis, Richard; Fong, Wen-fai; Fruchter, Andrew; Fynbo, Johan; Gehrels, Neil; Graham, John; Greiner, Jochen; Hjorth, Jens; Hunt, Leslie; Jakobsson, Pall; Kruehler, Thomas; Laskar, Tanmoy; Le Floc'h, Emerich; Levan, Andrew; Levesque, Emily; Littlejohns, Owen; Malesani, Daniele; Michalowski, Michal; Milvang-Jensen, Bo; Prochaska, J. Xavier; Salvaterra, Ruben; Schulze, Steve; Schady, Patricia; Tanvir, Nial; de Ugarte Postigo, Antonio; Vergani, Susanna; Watson, Darach

    2016-08-01

    Long-duration gamma-ray bursts act as beacons to the sites of star-formation in the distant universe. GRBs reveal galaxies too faint and star-forming regions too dusty to characterize in detail using any other method, and provide a powerful independent constraint on the evolution of the cosmic star-formation rate density at high-redshift. However, a full understanding of the GRB phenomenon and its relation to cosmic star-formation requires connecting the observations obtained from GRBs to the properties of the galaxies hosting them. The large majority of GRBs originate at moderate to high redshift (z>1) and Spitzer has proven crucial for understanding the host population, given its unique ability to observe the rest-frame NIR and its unrivaled sensitivity and efficiency. We propose to complete a comprehensive public legacy survey of the Swift GRB host population to build on our earlier successes and push beyond the statistical limits of previous, smaller efforts. Our survey will enable a diverse range of GRB and galaxy science including: (1) to quantitatively and robustly map the connection between GRBs and cosmic star-formation to constrain the GRB progenitor and calibrate GRB rate-based measurements of the high-z cosmic star-formation rate; (2) to constrain the luminosity function of star-forming galaxies at the faint end and at high redshift; (3) to understand how the ISM properties seen in absorption in high-redshift galaxies unveiled by GRBs - metallicity, dust column, dust properties - connect to global properties of the host galaxies such as mass and age. Building on a decade of experience at both observatories, our observations will create an enduring joint Swift-Spitzer legacy sample - providing the definitive resource with which to examine all aspects of the GRB/galaxy connection for years to come and setting the stage for intensive JWST follow-up of the most interesting sources from our sample.

  8. Tracing the evolution of Active Galactic Nuclei host galaxies over the last 9 Gyrs of Cosmic time

    CERN Document Server

    Goulding, Andy D; Hickox, Ryan C; Jones, Christine; Murray, Stephen S; Paggi, Alessandro; Ashby, Matthew L N; Coil, Alison L; Cooper, Michael C; Huang, Jiasheng; Kraft, Ralph; Newman, Jeffrey A; Weiner, Benjamin J; Willner, Steven P

    2013-01-01

    We present the results of a combined galaxy population analysis for the host galaxies of active galactic nuclei (AGN) identified at 0 < z < 1.4 within the SDSS, Bootes and DEEP2 surveys. We identified AGN in a uniform and unbiased manner at X-ray, infrared and radio wavelengths. Supermassive black holes undergoing radiatively-efficient accretion (detected as X-ray and/or infrared AGN) appear to be hosted in a separate and distinct galaxy population than AGN undergoing powerful mechanically dominated accretion (radio AGN). Consistent with some previous studies, radiatively efficient AGN appear to be preferentially hosted in modest star-forming galaxies, with little dependence on AGN or galaxy luminosity. AGN exhibiting radio-emitting jets due to mechanically-dominated accretion are almost exclusively observed in massive, passive galaxies. Crucially, we now provide strong evidence that the observed host-galaxy trends are independent of redshift. In particular, these different accretion-mode AGN have remai...

  9. Spectroscopic Confirmation of Two Lyman Break Galaxies at Redshift Beyond 7

    Science.gov (United States)

    Vanzella, E.; Pentericci, L.; Fontana, A.; Grazian, A.; Castellano, M.; Boutsia, K.; Cristiani, S.; Dickinson, M.; Gallozzi, S.; Giallongo, E.; Giavalisco, M.; Maiolino, R.; Moorwood, A.; Paris, D.; Santini, P.

    2011-04-01

    We report the spectroscopic confirmation of two Lyman break galaxies at redshift >7. The galaxies were observed as part of an ultra-deep spectroscopic campaign with FORS2 at the ESO/VLT for the confirmation of z ~= 7 "z-band dropout" candidates selected from our VLT/Hawk-I imaging survey. Both galaxies show a prominent emission line at 9735 Å and 9858 Å, respectively: the lines have fluxes of ~(1.6-1.2) × 10-17 erg s-1 cm-2 and exhibit a sharp decline on the blue side and a tail on the red side. The asymmetry is quantitatively comparable to the observed asymmetry in z ~ 6 Lyα lines, where absorption by neutral hydrogen in the intergalactic medium (IGM) truncates the blue side of the emission-line profile. We carefully evaluate the possibility that the galaxies are instead at lower redshift and we are observing either [O II], [O III], or Hα emission: however from the spectroscopic and the photometric data we conclude that there are no other plausible identifications, except for Lyα at redshift >7, implying that these are two of the most robust redshift determination for galaxies in the reionization epoch. Based on their redshifts and broadband photometry, we derive limits on the star formation rate and on the ultraviolet spectral slopes of the two galaxies. We argue that these two galaxies alone are unlikely to have ionized the IGM in their surroundings.

  10. Lyman alpha emission in starbursts: implications for galaxies at high redshift

    CERN Document Server

    Mas-Hesse, J M; Tenorio-Tagle, G; Leitherer, C; Terlevich, R J; Terlevich, E

    2003-01-01

    We present the results of a high resolution UV 2-D spectroscopic survey of star forming galaxies observed with HST-STIS. Our main aim was to map the Lyman alpha profiles to learn about the gas kinematics and its relation with the escape of Lyman alpha photons and to detect extended Lyman alpha emission due to scattering in gaseous halos. We have combined our data with previously obtained UV spectroscopy on other three star-forming galaxies. We find that the P-Cygni profile is spatially extended, smooth and spans several kiloparsecs covering a region much larger than the starburst itself. We propose a scenario whereby an expanding super-shell is generated by the interaction of the combined stellar winds and supernova ejecta from the young starbursts, with an extended low density halo. The variety of observed Lyman alpha profiles both in our sample and in high redshift starbursts is explained as phases in the time evolution of the super-shell expanding into the disk and halo of the host galaxy. The observed sha...

  11. VizieR Online Data Catalog: OmegaWINGS local clusters of galaxies redshifts (Moretti+, 2017)

    Science.gov (United States)

    Moretti, A.; Gullieuszik, M.; Poggianti, B.; Paccagnella, A.; Couch, W. J.; Vulcani, B.; Bettoni, D.; Fritz, J.; Cava, A.; Fasaano, G.; D'Onofrio, M.; Omizzolo, A.

    2017-02-01

    Redshifts, magnitude/radial completeness, and memberships are given for the 17985 galaxies observed as part of the OmegaWINGS survey of local clusters of galaxies over 1 square degree. Redshifts have been measured using both absorption and emission lines features. The sample magnitude completeness is 80% at V=20. Thanks to the observing strategy, the radial completeness turned out to be relatively constant (90%) within the AAOmega field of view. The success rate in measuring redshifts is 95%, at all radii. Cluster members are flagged 1 or 2, depending on the cluster structure/secondary structure, and 0 if they are not cluster members. (1 data file).

  12. AGN host galaxy mass function in COSMOS. Is AGN feedback responsible for the mass-quenching of galaxies?

    Science.gov (United States)

    Bongiorno, A.; Schulze, A.; Merloni, A.; Zamorani, G.; Ilbert, O.; La Franca, F.; Peng, Y.; Piconcelli, E.; Mainieri, V.; Silverman, J. D.; Brusa, M.; Fiore, F.; Salvato, M.; Scoville, N.

    2016-04-01

    We investigate the role of supermassive black holes in the global context of galaxy evolution by measuring the host galaxy stellar mass function (HGMF) and the specific accretion rate, that is, λSAR, the distribution function (SARDF), up to z ~ 2.5 with ~1000 X-ray selected AGN from XMM-COSMOS. Using a maximum likelihood approach, we jointly fit the stellar mass function and specific accretion rate distribution function, with the X-ray luminosity function as an additional constraint. Our best-fit model characterizes the SARDF as a double power-law with mass-dependent but redshift-independent break, whose low λSAR slope flattens with increasing redshift while the normalization increases. This implies that for a given stellar mass, higher λSAR objects have a peak in their space density at earlier epoch than the lower λSAR objects, following and mimicking the well-known AGN cosmic downsizing as observed in the AGN luminosity function. The mass function of active galaxies is described by a Schechter function with an almost constant M∗⋆ and a low-mass slope α that flattens with redshift. Compared to the stellar mass function, we find that the HGMF has a similar shape and that up to log (M⋆/M⊙) ~ 11.5, the ratio of AGN host galaxies to star-forming galaxies is basically constant (~10%). Finally, the comparison of the AGN HGMF for different luminosity and specific accretion rate subclasses with a previously published phenomenological model prediction for the "transient" population, which are galaxies in the process of being mass-quenched, reveals that low-luminosity AGN do not appear to be able to contribute significantly to the quenching and that at least at high masses, that is, M⋆ > 1010.7 M⊙, feedback from luminous AGN (log Lbol ≳ 46 [erg/s]) may be responsible for the quenching of star formation in the host galaxy.

  13. Fast outflows and star formation quenching in quasar host galaxies

    CERN Document Server

    Carniani, S; Maiolino, R; Balmaverde, B; Brusa, M; Cano-Díaz, M; Cicone, C; Comastri, A; Cresci, G; Fiore, F; Feruglio, C; La Franca, F; Mainieri, V; Mannucci, F; Nagao, T; Netzer, H; Piconcelli, E; Risaliti, G; Schneider, R; Shemmer, O

    2016-01-01

    Negative feedback from active galactic nuclei (AGN) is considered a key mechanism in shaping galaxy evolution. Fast, extended outflows are frequently detected in the AGN host galaxies at all redshifts and luminosities, both in ionised and molecular gas. However, these outflows are only "potentially" able to quench star formation and we are still missing a decisive evidence of negative feedback in action. Here we present Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) H- and K-band integral-field spectroscopic observations of two quasars at $z\\sim$2.4 characterised by fast, extended outflows detected through the [OIII]$\\lambda$5007 line (Carniani et al. 2015). The high signal-to-noise ratio of our observations allows us to identify faint narrow (FWHM $< 500$ km/s), and spatially extended components in [OIII]$\\lambda$5007 and H$\\alpha$ emission associated with star formation in the host galaxy. Such star-formation powered emission is spatially anti-correlated with the fast outflow...

  14. MegaZ-LRG: A photometric redshift catalogue of one million SDSS Luminous Red Galaxies

    CERN Document Server

    Collister, A A; Blake, C; Cannon, R; Croom, S; Drinkwater, M; Edge, A; Eisenstein, D; Loveday, J; Nichol, R; Pimbblet, K; De Propris, R; Roseboom, I; Ross, N; Schneider, D P; Shanks, T; Wake, D; Collister, Adrian; Lahav, Ofer; Blake, Chris; Cannon, Russell; Croom, Scott; Drinkwater, Michael; Edge, Alastair; Eisenstein, Daniel; Loveday, Jon; Nichol, Robert; Pimbblet, Kevin; Propris, Roberto De; Roseboom, Isaac; Ross, Nic; Schneider, Donald P.; Shanks, Tom; Wake, David

    2006-01-01

    We describe the construction of MegaZ-LRG, a photometric redshift catalogue of over one million luminous red galaxies (LRGs) in the redshift range 0.4 < z < 0.7 with limiting magnitude i < 20. The catalogue is selected from the imaging data of the Sloan Digital Sky Survey Data Release 4. The 2dF-SDSS LRG and Quasar (2SLAQ) spectroscopic redshift catalogue of 13,000 intermediate-redshift LRGs provides a photometric redshift training set, allowing use of ANNz, a neural network-based photometric-redshift estimator. The rms photometric redshift accuracy obtained for an evaluation set selected from the 2SLAQ sample is sigma_z = 0.049 averaged over all galaxies, and sigma_z = 0.040 for a brighter subsample (i < 19.0). The catalogue is expected to contain ~5 per cent stellar contamination. The ANNz code is used to compute a refined star/galaxy probability based on a range of photometric parameters; this allows the contamination fraction to be reduced to 2 per cent with negligible loss of genuine galaxies...

  15. The Main Sequences of Starforming Galaxies and Active Galactic Nuclei at High Redshift

    CERN Document Server

    Mancuso, Claudia; Shi, J; Gonzàlez-Nuevo, J; Bèthermin, M; Danese, L

    2016-01-01

    We provide a novel, unifying physical interpretation on the origin, the average shape, the scatter, and the cosmic evolution for the main sequences of starforming galaxies and active galactic nuclei at high redshift z $\\gtrsim$ 1. We achieve this goal in a model-independent way by exploiting: (i) the redshift-dependent SFR functions based on the latest UV/far-IR data from HST/Herschel, and re- lated statistics of strong gravitationally lensed sources; (ii) deterministic evolutionary tracks for the history of star formation and black hole accretion, gauged on a wealth of multiwavelength observations including the observed Eddington ratio distribution. We further validate these ingredients by showing their consistency with the observed galaxy stellar mass functions and AGN bolometric luminosity functions at different redshifts via the continuity equation approach. Our analysis of the main sequence for high-redshift galaxies and AGNs highlights that the present data are consistently interpreted in terms of an in...

  16. Simultaneous constraints on cosmology and photometric redshift bias from weak lensing and galaxy clustering

    Science.gov (United States)

    Samuroff, S.; Troxel, M. A.; Bridle, S. L.; Zuntz, J.; MacCrann, N.; Krause, E.; Eifler, T.; Kirk, D.

    2017-02-01

    We investigate the expected cosmological constraints from a combination of cosmic shear and large-scale galaxy clustering using realistic photometric redshift distributions. Introducing a systematic bias in the lensing distributions (of 0.05 in redshift) produces a >2σ bias in the recovered matter power spectrum amplitude and dark energy equation of state for preliminary Stage III surveys. We demonstrate that cosmological error can be largely removed by marginalizing over biases in the assumed weak-lensing redshift distributions. Furthermore, the cosmological constraining power is retained despite removing much of the information on the lensing redshift biases. This finding relies upon high-quality redshift estimates for the clustering sample, but does not require spectroscopy. All galaxies in this analysis can thus be assumed to come from a single photometric survey. We show that this internal constraint on redshift biases arises from complementary degeneracy directions between cosmic shear and the combination of galaxy clustering and shear-density cross-correlations. Finally we examine a case where the assumed redshift distributions differ from the truth by more than a simple uniform bias. We find that the effectiveness of this self-calibration method will depend on the survey details and the nature of the uncertainties on the estimated redshift distributions.

  17. A Photometric Redshift Galaxy Catalog from the Red-Sequence Cluster Survey

    CERN Document Server

    Hsieh, B C; Lin, H; Gladders, M D

    2005-01-01

    The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the $z'$ and $R_c$ bands for ~90 square degrees of sky, and supplemental $V$ and $B$ data have been obtained for 33.6 deg$^{2}$. We compile a photometric redshift catalog from these 4-band data by utilizing the empirical quadratic polynomial photometric redshift fitting technique in combination with CNOC2 and GOODS/HDF-N redshift data. The training set includes 4924 spectral redshifts. The resulting catalog contains more than one million galaxies with photometric redshifts $< 1.5$ and $R_c < 24$, giving an rms scatter $\\sigma(\\Delta{z}) < 0.06$ within the redshift range $0.2 < z < 0.5$ and $\\sigma(\\Delta{z}) < 0.11$ for galaxies at $0.0 < z < 1.5$. We describe the empirical quadratic polynomial photometric redshift fitting technique which we use to determine the relation between redshift and photometry. A kd-tree algorithm is used to divide up our sample to improve the accuracy of our cat...

  18. Detection of three Gamma-Ray Burst host galaxies at $z\\sim6$

    CERN Document Server

    McGuire, J T W; Levan, A J; Trenti, M; Stanway, E R; Shull, J M; Wiersema, K; Perley, D A; Starling, R L C; Bremer, M; Stocke, J T; Hjorth, J; Rhoads, J E; Levesque, E M; Robertson, B; Fynbo, J P U; Ellis, R S; Fruchter, A S; Perna, R

    2015-01-01

    Gamma-ray bursts allow us to pinpoint and study star-forming galaxies in the early universe, thanks to their immense luminosities and association with deaths of massive stars. We present {\\em Hubble Space Telescope} Wide Field Camera 3 detections of three {\\em Swift} GRBs lying at redshifts $z = 5.913$ (GRB 130606A), $z = 6.295$ (GRB 050904), and $z = 6.327$ (GRB 140515A) in the F140W (wide-$JH$ band, $\\lambda_{\\rm{obs}}\\sim1.4\\,\\mu m$) filter. The hosts have magnitudes (corrected for Galactic extinction) of $m_{\\rm{\\lambda_{obs},AB}}= 26.26^{+0.12}_{-0.14}, 27.63^{+0.16}_{-0.18},$ and $28.23^{+0.24}_{-0.30}$ respectively. In all three cases the probability of chance coincidence of lower redshift galaxies is $\\lesssim1.5\\%$, indicating that the detected galaxies are most likely the GRB hosts. These are the first detections of high redshift ($z > 5$) GRB host galaxies in emission. The galaxies have luminosities in the range $0.1-0.7\\,L^{*}_{z=6}$ (with $M_{1600}^{*}=-20.95\\pm0.12$), along with half-light radii...

  19. Rapidly growing black holes and host galaxies in the distant Universe from the Herschel Radio Galaxy Evolution Project

    CERN Document Server

    Drouart, G; Vernet, J; Seymour, N; Lehnert, M; Barthel, P; Bauer, F E; Ibar, E; Galametz, A; Haas, M; Hatch, N; Mullaney, J R; Nesvadba, N; Rocca-Volmerange, B; Rottgering, H J A; Stern, D; Wylezalek, D

    2014-01-01

    We present results from a survey of 70 radio galaxies (RGs) at redshifts 12.5 are higher than the sSFR of typical star-forming galaxies over the same redshift range but are similar or perhaps lower than the galaxy population for RGs at z<2.5. By comparing the sSFR and the specific black hole mass accretion rate, we conclude that BHs in radio loud AGN are already, or soon will be, overly massive compared to their host galaxies in terms of expectations from the local MBH-MGal relation. In order to ``catch up'' with the BH, the galaxies require about an order-of magnitude more time to grow in mass, at the observed SFRs, compared to the time the BH is actively accreting. However, during the current cycle of activity, we argue that this catching-up is likely to be difficult due to the short gas depletion times. Finally, we speculate on how the host galaxies might grow sufficiently in stellar mass to ultimately fall onto the local MBH-MGal relation.

  20. Cosmological constraints from the redshift dependence of the Alcock-Paczynski test: galaxy density gradient field

    CERN Document Server

    Li, Xiao-Dong; Forero-Romero, Jaime E; Kim, Juhan

    2014-01-01

    We propose a method based on the redshift dependence of the Alcock-Paczynski (AP) test to measure the expansion history of the Universe. It uses the isotropy of the galaxy density gradient field to constrain cosmological parameters. If the density parameter $\\Omega_m$ or the dark energy equation of state $w$ are incorrectly chosen, the gradient field appears to be anisotropic with the degree of anisotropy varying with redshift. We use this effect to constrain the cosmological parameters governing the expansion history of the Universe. Although redshift-space distortions (RSD) induced by galaxy peculiar velocities also produce anisotropies in the gradient field, these effects are close to uniform in magnitude over a large range of redshift. This makes the redshift variation of the gradient field anisotropy relatively insensitive to the RSD. By testing the method on mock surveys drawn from the Horizon Run 3 cosmological N-body simulations, we demonstrate that the cosmological parameters can be estimated without...

  1. Redshift Measurement and Spectral Classification for eBOSS Galaxies with the Redmonster Software

    CERN Document Server

    Hutchinson, Timothy A; Dawson, Kyle S; Prieto, Carlos Allende; Bailey, Stephen; Bautista, Julian E; Brownstein, Joel R; Conroy, Charlie; Guy, Julien; Myers, Adam D; Newman, Jeffrey A; Prakash, Abhishek; Carnero-Rosell, Aurelio; Seo, Hee-Jong; Vivek, M; Zhu, Guangtun Ben

    2016-01-01

    We describe the redmonster automated redshift measurement and spectral classification software designed for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). We describe the algorithms, the template standard and requirements, and the newly developed galaxy templates to be used on eBOSS spectra. We present results from testing on early data from eBOSS, where we have found a 90.5% automated redshift and spectral classification success rate for the luminous red galaxy sample (redshifts 0.6 $\\lesssim$ $z$ $\\lesssim$ 1.0). The \\texttt{redmonster} performance meets the eBOSS cosmology requirements for redshift classification and catastrophic failures, and represents a significant improvement over the previous pipeline. We describe the empirical processes used to determine the optimum number of additive polynomial terms in our models and an acceptable $\\Delta\\chi_r^2$ threshold for declaring statistical confidence. Statistical errors on redshift measurement du...

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

    CERN Document Server

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

    2013-01-01

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

  3. Why do high-redshift galaxies show diverse gas-phase metallicity gradients?

    CERN Document Server

    Ma, Xiangcheng; Feldmann, Robert; Torrey, Paul; Faucher-Giguere, Claude-Andre; Keres, Dusan

    2016-01-01

    Recent spatially resolved observations of galaxies at z=0.6-3 reveal that high-redshift galaxies show complex kinematics and a broad distribution of gas-phase metallicity gradients. To understand these results, we use a suite of high-resolution cosmological zoom-in simulations from the Feedback in Realistic Environments (FIRE) project, which include physically motivated models of the multi-phase ISM, star formation, and stellar feedback. Our simulations reproduce the observed diversity of kinematic properties and metallicity gradients, broadly consistent with observations at z=0-3. Strong negative metallicity gradients only appear in galaxies with a rotating disk, but not all rotationally supported galaxies have significant gradients. Strongly perturbed galaxies with little rotation always have flat gradients. The kinematic properties and metallicity gradient of a high-redshift galaxy can vary significantly on short time-scales, associated with starburst episodes. Feedback from a starburst can destroy the gas...

  4. A Search for Moderate-Redshift Survivors from the Population of Luminous Compact Passive Galaxies at High Redshift

    CERN Document Server

    Stockton, Alan; Larson, Kirsten; Mann, Andrew W

    2013-01-01

    From a search of a ~ 2400 square degree region covered by both the SDSS and UKIDSS databases, we have attempted to identify galaxies at z ~ 0.5 that are consistent with their being essentially unmodified examples of the luminous passive compact galaxies found at z ~ 2.5. After isolating good candidates via deeper imaging, we further refine the sample with Keck moderate-resolution spectroscopy and laser-guide-star adaptive-optics imaging. For 4 of the 5 galaxies that so far remain after passing through this sieve, we analyze plausible star-formation histories based on our spectra in order to identify galaxies that may have survived with little modification from the population formed at high redshift. We find 2 galaxies that are consistent with having formed > 95% of their mass at z > 5. We attempt to estimate masses both from our stellar population determinations and from velocity dispersions. Given the high frequency of small axial ratios, both in our small sample and among samples found at high redshifts, we...

  5. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Star formation history of passive galaxies

    CERN Document Server

    Siudek, M; Scodeggio, M; Garilli, B; Pollo, A; Haines, C P; Fritz, A; Bolzonella, M; de la Torre, S; Granett, B R; Guzzo, L; Abbas, U; Adami, C; Bottini, D; Cappi, A; Cucciati, O; De Lucia, G; Davidzon, I; Franzetti, P; Iovino, A; Krywult, J; Brun, V Le; Fèvre, O Le; Maccagni, D; Marchetti, A; Marulli, F; Polletta, M; Tasca, L A M; Tojeiro, R; Vergani, D; Zanichelli, A; Arnouts, S; Bel, J; Branchini, E; Ilbert, O; Gargiulo, A; Moscardini, L; Takeuchi, T T; Zamorani, G

    2016-01-01

    We trace the evolution and the star formation history of passive galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). We extracted from the VIPERS survey a sample of passive galaxies in the redshift range 0.4galaxies. We characterize the formation redshift-stellar mass relation for intermediate-redshift passive galaxies. We find that at $z\\sim1$ stellar populations in low-mass passive galaxies are younger than in high-mass passive galaxies, similarly to what is observed at the present epoch. Over the full analyzed redshift and stellar mass range, the...

  6. Exploring The Gas Cycle In High-redshift Galaxies: A Joint Effort Of Theory And Observations

    Science.gov (United States)

    Fumagalli, Michele

    2012-01-01

    The evolution of high-redshift galaxies is regulated by the balance between the inflow of fresh fuel for star formation and the outflow of metal-polluted material from star forming regions. Hydrodynamic cosmological simulations indicate that galaxies at high redshifts are fed by extended streams of cold gas in a smooth component and in merging satellites, but direct evidence of this mode of accretion is lacking. To investigate the signatures of these "cold streams" in observations, we have studied the Lyman-α emission and hydrogen absorption properties in galaxies simulated at high-resolution, using state-of-the-art radiative transfer codes. I will present these model predictions and I will compare and contrast results of simulations with observations of high-redshift Lyman break galaxies. I will also discuss the prospects of mapping the circumgalactic medium with absorption line systems and present preliminary results from ongoing observations.

  7. Redshift and luminosity evolution of the intrinsic alignments of galaxies in Horizon-AGN

    CERN Document Server

    Chisari, Nora Elisa; Codis, Sandrine; Dubois, Yohan; Devriendt, Julien; Miller, Lance; Benabed, Karim; Slyz, Adrianne; Gavazzi, Raphael; Pichon, Christophe

    2016-01-01

    Intrinsic galaxy shape and angular momentum alignments can arise in cosmological large-scale structure due to tidal interactions or galaxy formation processes. Cosmological hydrodynamical simulations have recently come of age as a tool to study these alignments and their contamination to weak gravitational lensing. We probe the redshift and luminosity evolution of intrinsic alignments in Horizon-AGN between $z=0$ and $z=3$ for galaxies with an $r$-band absolute magnitude of $M_r\\leq-20$. Alignments transition from being radial at low redshifts and high luminosities, dominated by the contribution of ellipticals, to being tangential at high redshift and low luminosities, where discs dominate the signal. This cannot be explained by the evolution of the fraction of ellipticals and discs alone: intrinsic evolution in the amplitude of alignments is necessary. We constrain the evolution of the alignment amplitude as a function of luminosity for elliptical galaxies alone and find it to be in good agreement with curre...

  8. Photometric redshifts and clustering of emission line galaxies selected jointly by DES and eBOSS

    CERN Document Server

    Jouvel, S; Comparat, J; Carnero, A; Camacho, H; Abdalla, F B; Kneib, J-P; Merson, A; Lima, M; Sobreira, F; da Costa, Luiz; Prada, F; Zhu, G B; Benoit-Levy, A; De La Macora, A; Kuropatkin, N; Lin, H; Abbott, T M C; Allam, S; Banerji, M; Bertin, E; Brooks, D; Capozzi, D; Kind, M Carrasco; Carretero, J; Castander, F J; Cunha, C E; Desai, S; Doel, P; Eifler, T F; Estrada, J; Neto, A Fausti; Flaugher, B; Fosalba, P; Frieman, J; Gaztanaga, E; Gerdes, D W; Gruen, D; Gruendl, R A; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Lahav, O; Li, T S; Maia, M A G; March, M; Marshall, J L; Miquel, R; Percival, W J; Plazas, A A; Reil, K; Romer, A K; Roodman, A; Rykoff, E S; Sako, M; Sanchez, E; Santiago, B; Scarpine, V; Sevilla-Noarbe, I; Santos, M Soares; Suchyta, E; Tarle, G; Thaler, J; Thomas, D; Walker, A; Zhang, Y

    2015-01-01

    We present the results of the first test plates of the extended Baryon Oscillation Spectroscopic Survey. This paper focuses on the emission line galaxies (ELG) population targetted from the Dark Energy Survey (DES) photometry. We analyse the success rate, efficiency, redshift distribution, and clustering properties of the targets. From the 9000 spectroscopic redshifts targetted, 4600 have been selected from the DES photometry. The total success rate for redshifts between 0.6 and 1.2 is 71\\% and 68\\% respectively for a bright and faint, on average more distant, samples including redshifts measured from a single strong emission line. We find a mean redshift of 0.8 and 0.87, with 15 and 13\\% of unknown redshifts respectively for the bright and faint samples. In the redshift range 0.6redshifts, the mean redshift for the bright and faint sample is 0.85 and 0.9 respectively. Star contamination is lower than 2\\%. We measure a galaxy bias averaged on scales of 1 and 10~...

  9. Cl 1103.7-1245 at z=0.96: the highest redshift galaxy cluster in the EDisCS survey

    CERN Document Server

    Vulcani, Benedetta; Poggianti, Bianca M; Milvang-Jensen, Bo; von der Linden, Anja; Fritz, Jacopo; Jablonka, Pascale; Johnson, Olivia; Zaritsky, Dennis

    2012-01-01

    We present new spectroscopic observations in a field containing the highest redshift cluster of the ESO Distant Cluster Survey (EDisCS). We measure galaxy redshifts and determine the velocity dispersions of the galaxy structures located in this field. Together with the main cluster Cl1103.7$-$1245 (z=0.9580; sigma_{clus} = 522 +/- 111 km/s) we find a secondary structure at z=0.9830, Cl1103.7-1245c. We then characterize the galaxy properties in both systems, and find that they contain very different galaxy populations. The cluster Cl1103.7-1245 hosts a mixture of passive elliptical galaxies and star-forming spirals and irregulars. In the secondary structure Cl1103.7-1245c all galaxies are lower-mass star-forming irregulars and peculiars. In addition, we compare the galaxy populations in the Cl1103.7-1245 z=0.9580 cluster with those in lower redshift EDisCS clusters with similar velocity dispersions. We find that the properties of the galaxies in Cl1103.7-1245 follow the evolutionary trends found at lower redsh...

  10. AGN Absorption Linked to Host Galaxies

    CERN Document Server

    Juneau, Stéphanie

    2013-01-01

    Multiwavelength identification of AGN is crucial not only to obtain a more complete census, but also to learn about the physical state of the nuclear activity (obscuration, efficiency, etc.). A panchromatic strategy plays an especially important role when the host galaxies are star-forming. Selecting far-Infrared galaxies at 0.3host galaxies, indicating a physical link between X-ray absorption and either the gas fraction or the gas geometry in the hosts. These findings have implications for our current understanding of both the AGN unification model and the nature of the black hole-galaxy connection. These proceedi...

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

    Science.gov (United States)

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

    1999-08-01

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

  12. The redshift-space two-point correlation functions of galaxies and groups in the Nearby Optical Galaxy sample

    CERN Document Server

    Giuricin, G; Girardi, M; Mezzetti, M; Marinoni, C; Giuricin, Giuliano; Samurovic, Srdjan; Girardi, Marisa; Mezzetti, Marino; Marinoni, Christian

    2001-01-01

    We use the two-point correlation function in redshift space, $\\xi(s)$, to study the clustering of the galaxies and groups of the Nearby Optical Galaxy (NOG) sample, which is a nearly all-sky, complete, magnitude-limited sample of $\\sim$7000 bright and nearby optical galaxies. The correlation function of galaxies is well described by a power law, $\\xi(s)=(s/s_0)^{-\\gamma}$, with slope $\\gamma\\sim1.5$ and $s_0\\sim6.4 h^{-1}$Mpc (on scales $2.7 - 12 h^{-1}$Mpc), in agreement with previous results of several redshift surveys of optical galaxies. We confirm the existence of morphological segregation between early- and late-type galaxies and, in particular, we find a gradual decreasing of the strength of clustering from the S0 galaxies to the late-type spirals, on intermediate scales. Furthermore, luminous galaxies turn out to be more clustered than dim galaxies. The luminosity segregation, which is significant for both early- and late-type objects, starts to become appreciable only for galaxies brighter than $M_B\\...

  13. The bispectrum of galaxies from high-redshift galaxy surveys: Primordial non-Gaussianity and non-linear galaxy bias

    Energy Technology Data Exchange (ETDEWEB)

    Sefusatti, Emiliano; /Fermilab; Komatsu, Eiichiro; /Texas U., Astron. Dept.

    2007-05-01

    The greatest challenge in the interpretation of galaxy clustering data from any surveys is galaxy bias. Using a simple Fisher matrix analysis, we show that the bispectrum provides an excellent determination of linear and non-linear bias parameters of intermediate and high-z galaxies, when all measurable triangle configurations down to mildly non-linear scales, where perturbation theory is still valid, are included. The bispectrum is also a powerful probe of primordial non-Gaussianity. The planned galaxy surveys at z {approx}> 2 should yield constraints on non-Gaussian parameters, f{sub NL}{sup loc.} and f{sub NL}{sup eq.}, that are comparable to, or even better than, those from CMB experiments. We study how these constraints improve with volume, redshift range, as well as the number density of galaxies. Finally we show that a halo occupation distribution may be used to improve these constraints further by lifting degeneracies between gravity, bias, and primordial non-Gaussianity.

  14. Dark-ages Reionization & Galaxy Formation Simulation I: The dynamical lives of high redshift galaxies

    CERN Document Server

    Poole, Gregory B; Mutch, Simon J; Power, Chris; Duffy, Alan R; Geil, Paul M; Mesinger, Andrei; Wyithe, Stuart B

    2015-01-01

    We present the Dark-ages Reionization and Galaxy-formation Observables from Numerical Simulations (DRAGONS) program and Tiamat, the collisionless N-body simulation program upon which DRAGONS is built. The primary trait distinguishing Tiamat from other large simulation programs is its density of outputs at high redshift (100 from z=35 to z=5; roughly one every 10 Myr) enabling the construction of very accurate merger trees at an epoch when galaxy formation is rapid and mergers extremely frequent. We find that the friends-of-friends halo mass function agrees well with the prediction of Watson et al. at high masses, but deviates at low masses, perhaps due to our use of a different halo finder or perhaps indicating a break from "universal" behaviour. We then analyse the dynamical evolution of galaxies during the Epoch of Reionization finding that only a small fraction (~20%) of galactic halos are relaxed. We illustrate this using standard relaxation metrics to establish two dynamical recovery time-scales: i) halo...

  15. Galaxy and Mass Assembly (GAMA): Colour and luminosity dependent clustering from calibrated photometric redshifts

    CERN Document Server

    Christodoulou, L; Loveday, J; Norberg, P; Baldry, I K; Hurley, P D; Driver, S P; Bamford, S P; Hopkins, A M; Liske, J; Peacock, J A; Bland-Hawthorn, J; Brough, S; Cameron, E; Conselice, C J; Croom, S M; Frenk, C S; Gunawardhana, M; Jones, D H; Kelvin, L S; Kuijken, K; Nichol, R C; Parkinson, H; Pimbblet, K A; Popescu, C C; Prescott, M; Robotham, A S G; Sharp, R G; Sutherland, W J; Taylor, E N; Thomas, D; Tuffs, R J; van Kampen, E; Wijesinghe, D

    2012-01-01

    We measure the two-point angular correlation function of a sample of 4,289,223 galaxies with r < 19.4 mag from the Sloan Digital Sky Survey as a function of photometric redshift, absolute magnitude and colour down to M_r - 5log h = -14 mag. Photometric redshifts are estimated from ugriz model magnitudes and two Petrosian radii using the artificial neural network package ANNz, taking advantage of the Galaxy and Mass Assembly (GAMA) spectroscopic sample as our training set. The photometric redshifts are then used to determine absolute magnitudes and colours. For all our samples, we estimate the underlying redshift and absolute magnitude distributions using Monte-Carlo resampling. These redshift distributions are used in Limber's equation to obtain spatial correlation function parameters from power law fits to the angular correlation function. We confirm an increase in clustering strength for sub-L* red galaxies compared with ~L* red galaxies at small scales in all redshift bins, whereas for the blue populati...

  16. Preliminary Results on VLT K-band Imaging Observations of GRB Host Galaxies

    Indian Academy of Sciences (India)

    E. Le Floc’h; I. F. Mirabel; P.-A. Duc

    2002-03-01

    We have obtained -band imaging observations of Gamma-Ray Burst (GRB) host galaxies with the near-infrared spectro-imager ISAAC installed on the Very Large Telescope at Paranal (Chile). The derived magnitudes, combined with other photometric data taken from the literature, are used to investigate the – colors of GRB hosts. We do not find any extremely reddened starbursts in our sample, despite the capability of GRBs to trace star formation even in dusty regions. The observed – colors are on the contrary typical of irregular and spiral blue galaxies at high redshift.

  17. Predicting the Redshift 2 H-Alpha Luminosity Function Using [OIII] Emission Line Galaxies

    Science.gov (United States)

    Mehta, Vihang; Scarlata, Claudia; Colbert, James W.; Dai, Y. S.; Dressler, Alan; Henry, Alaina; Malkan, Matt; Rafelski, Marc; Siana, Brian; Teplitz, Harry I.; Bagley, Micaela; Beck, Melanie; Ross, Nathaniel R.; Rutkowski, Michael; Wang, Yun

    2015-01-01

    Upcoming space-based surveys such as Euclid and WFIRST-AFTA plan to measure Baryonic Acoustic Oscillations (BAOs) in order to study dark energy. These surveys will use IR slitless grism spectroscopy to measure redshifts of a large number of galaxies over a significant redshift range. In this paper, we use the WFC3 Infrared Spectroscopic Parallel Survey (WISP) to estimate the expected number of H-alpha emitters observable by these future surveys. WISP is an ongoing Hubble Space Telescope slitless spectroscopic survey, covering the 0.8 - 1.65 micrometers wavelength range and allowing the detection of H-alpha emitters up to z approximately equal to 1.5 and [OIII] emitters to z approximately equal to 2.3. We derive the H-alpha-[OIII] bivariate line luminosity function for WISP galaxies at z approximately equal to 1 using a maximum likelihood estimator that properly accounts for uncertainties in line luminosity measurement, and demonstrate how it can be used to derive the H-alpha luminosity function from exclusively fitting [OIII] data. Using the z approximately equal to 2 [OIII] line luminosity function, and assuming that the relation between H-alpha and [OIII] luminosity does not change significantly over the redshift range, we predict the H-alpha number counts at z approximately equal to 2 - the upper end of the redshift range of interest for the future surveys. For the redshift range 0.7 less than z less than 2, we expect approximately 3000 galaxies per sq deg for a flux limit of 3 x 10(exp -16) ergs per sec per sq cm (the proposed depth of Euclid galaxy redshift survey) and approximately 20,000 galaxies per sq deg for a flux limit of approximately 10(exp -16) ergs per sec per sq cm (the baseline depth of WFIRST galaxy redshift survey).

  18. N-body simulations of gravitational redshifts and other relativistic distortions of galaxy clustering

    Science.gov (United States)

    Zhu, Hongyu; Alam, Shadab; Croft, Rupert A. C.; Ho, Shirley; Giusarma, Elena

    2017-10-01

    Large redshift surveys of galaxies and clusters are providing the first opportunities to search for distortions in the observed pattern of large-scale structure due to such effects as gravitational redshift. We focus on non-linear scales and apply a quasi-Newtonian approach using N-body simulations to predict the small asymmetries in the cross-correlation function of two galaxy different populations. Following recent work by Bonvin et al., Zhao and Peacock and Kaiser on galaxy clusters, we include effects which enter at the same order as gravitational redshift: the transverse Doppler effect, light-cone effects, relativistic beaming, luminosity distance perturbation and wide-angle effects. We find that all these effects cause asymmetries in the cross-correlation functions. Quantifying these asymmetries, we find that the total effect is dominated by the gravitational redshift and luminosity distance perturbation at small and large scales, respectively. By adding additional subresolution modelling of galaxy structure to the large-scale structure information, we find that the signal is significantly increased, indicating that structure on the smallest scales is important and should be included. We report on comparison of our simulation results with measurements from the SDSS/BOSS galaxy redshift survey in a companion paper.

  19. Discovery of Compact Quiescent Galaxies at Intermediate Redshifts in DEEP2

    Science.gov (United States)

    Blancato, Kirsten; Chilingarian, Igor; Damjanov, Ivana; Moran, Sean; Katkov, Ivan

    2015-01-01

    Compact quiescent galaxies in the redshift range 0.6 histories of these objects from the high redshift z ≥ 2 Universe to the local z ~ 0 Universe. We identify the first intermediate redshift compact quiescent galaxies by searching a sample of 1,089 objects in the DEEP2 Redshift Survey that have multi-band photometry, spectral fitting, and readily available structural parameters. We find 27 compact quiescent candidates between z = 0.6 and z = 1.1 where each candidate galaxy has archival Hubble Space Telescope (HST) imaging and is visually confirmed to be early-type. The candidates have half-light radii ranging from 0.83 2 which suggests these objects may be the relics of the observed high redshift compact galaxies and formation at z ≤ 2 which suggests there is an additional population of more recently formed massive compact galaxies. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  20. Galaxy And Mass Assembly (GAMA): The dependence of the galaxy luminosity function on environment, redshift and colour

    CERN Document Server

    McNaught-Roberts, Tamsyn; Baugh, Carlton; Lacey, Cedric; Loveday, J; Peacock, J; Baldry, I; Bland-Hawthorn, J; Brough, S; Driver, Simon P; Robotham, A S G; Vazquez-Mata, J A

    2014-01-01

    We use 80922 galaxies in the Galaxy And Mass Assembly (GAMA) survey to measure the galaxy luminosity function (LF) in different environments over the redshift range 0.04redshift to measure the dependence of the LF on environment, redshift and colour. We find that the LF varies smoothly with overdensity, consistent with previous results, with little environmental dependent evolution over the last 3 Gyrs. The modified GALFORM model predictions agree remarkably well with our LFs split by environment, particularly in the most overdense environments. The LFs predicted by the model for both blue and red galaxies are consistent with GAMA for the environments and luminosities at which such galaxies dominate. Discrepancies between the model and the data seen in the faint end of the LF suggest too many faint red galaxies are predicted, which is likely to be due to the over-quenching of satellite galaxies. The excess of bright blue...

  1. Optical imaging of the host galaxies of X-ray selected BL Lacertae objects

    CERN Document Server

    Falomo, R

    1999-01-01

    We investigate the properties of the host galaxies of X-ray selected (high frequency peaked) BL Lac objects using a large and homogeneous data set of high spatial resolution R-band observations of 52 BL Lacs in the EMSS and Slew samples. The redshift distribution of the BL Lacs ranges from z = 0.04 to z>0.7, with average and median redshifts z = 0.26 and z = 0.24, respectively. Eight objects are at unknown redshift. We are able to resolve 45 objects out of the 52 BL Lacs. For all the well-resolved sources, we find the host to be a luminous elliptical galaxy. In a few cases a disk is not ruled out but an elliptical model is still preferred. The average absolute magnitude of the host galaxies is = -23.9+-0.6, while the average scale length of the host is = 9+-5 kpc. There is no difference in the host properties between the EMSS and Slew samples. We find a good agreement between the results derived by the surveys of Wurtz et al. (ground-based data) and Urry et al. (HST data), and by our new deeper imaging. The...

  2. The DEEP3 Galaxy Redshift Survey: The Impact of Environment on the Size Evolution of Massive Early-type Galaxies at Intermediate Redshift

    CERN Document Server

    Cooper, Michael C; Newman, Jeffrey A; Coil, Alison L; Davis, Marc; Dutton, Aaron A; Faber, S M; Guhathakurta, Puragra; Koo, David C; Lotz, Jennifer M; Weiner, Benjamin J; Willmer, Christopher N A; Yan, Renbin

    2011-01-01

    Using data drawn from the DEEP2 and DEEP3 Galaxy Redshift Surveys, we investigate the relationship between the environment and the structure of galaxies residing on the red sequence at intermediate redshift. Within the massive (10 < log(M*/Msun) < 11) early-type population at 0.4 < z <1.2, we find a significant correlation between local galaxy overdensity (or environment) and galaxy size, such that early-type systems in higher-density regions tend to have larger effective radii (by ~0.5 kpc or 25% larger) than their counterparts of equal stellar mass and Sersic index in lower-density environments. This observed size-density relation is consistent with a model of galaxy formation in which the evolution of early-type systems at z < 2 is accelerated in high-density environments such as groups and clusters and in which dry, minor mergers (versus mechanisms such as quasar feedback) play a central role in the structural evolution of the massive, early-type galaxy population.

  3. Detection of Large-Scale Structure in a $B<17^{m}$ Galaxy Redshift Survey

    CERN Document Server

    Ratcliffe, A; Broadbent, A J; Parker, Q A; Watson, F G; Oates, A P; Fong, R; Collins, C A

    1996-01-01

    We report on results from the Durham/UKST Galaxy Redshift Survey where we have found large scale ``cellular'' features in the galaxy distribution. These have spatial 2-point correlation function power significantly in excess of the predictions of the standard cold dark matter cosmological model^{1}, supporting the previous observational results from the APM survey^{2,3}. At smaller scales, the 1-D pairwise galaxy velocity dispersion is measured to be \\bf 387^{+96}_{-62} kms^{-1} which is also inconsistent with the prediction of the standard cold dark matter model^{1}. Finally, the survey has produced the most significant detection yet of large scale redshift space distortions due to dynamical infall of galaxies^{4}. An estimate of \\bf \\Omega^{0.6}/b = 0.55 \\pm 0.12 is obtained which is consistent either with a low density Universe or a critical density Universe where galaxies are biased tracers of the mass.

  4. The host galaxies of micro-Jansky radio sources

    CERN Document Server

    Luchsinger, K M; Jones, K M; Mauduit, J C; Pforr, J; Surace, J A; Vaccari, M; Farrah, D; Gonzales-Solares, E; Jarvis, M J; Maraston, C; Marchetti, L; Oliver, S; Afonso, J; Cappozi, D; Sajina, A

    2015-01-01

    We combine a deep 0.5~deg$^2$, 1.4~GHz deep radio survey in the Lockman Hole with infrared and optical data in the same field, including the SERVS and UKIDSS near-infrared surveys, to make the largest study to date of the host galaxies of radio sources with typical radio flux densities $\\sim 50 \\;\\mu$Jy. 87% (1274/1467) of radio sources have identifications in SERVS to $AB\\approx 23.1$ at 3.6 or 4.5$\\mu$m, and 9% are blended with bright objects (mostly stars), leaving only 4% (59 objects) which are too faint to confidently identify in the near-infrared. We are able to estimate photometric redshifts for 68% of the radio sources. We use mid-infrared diagnostics to show that the source population consists of a mixture of star forming galaxies, rapidly accreting (cold mode) AGN and low accretion rate, hot mode AGN, with neither AGN nor starforming galaxies clearly dominating. We see the breakdown in the $K-z$ relation in faint radio source samples, and show that it is due to radio source populations becoming domi...

  5. Simulating the COSMOS: The fraction of merging galaxies at high redshift

    CERN Document Server

    Kampczyk, P; Carollo, C M; Scarlata, C; Feldmann, R; Koekemoer, A; Leauthaud, A; Taniguchi, Y; Capak, P

    2006-01-01

    Simulations of nearby (0.015 < z < 0.025) SDSS galaxies have been used to reproduce as accurately as possible the appearance that they would have on COSMOS ACS images if they had been observed at z ~ 0.7 and z ~ 1.2. By adding the SDSS galaxies to random locations in the COSMOS images, we simulate the effects of chance superpositions of high redshift galaxies with unrelated foreground or background objects. We have used these simulated images, together with those of real COSMOS galaxies at these same redshifts, to undertake a "blind" morphological classification of galaxies to identify those that appear to be undergoing mergers and thus to estimate the change in merger fraction with redshift. We find that real mergers are harder to recognize at high redshift, and also that the chance superposition of unrelated galaxies often produces the appearance of mergers where in reality none exists. In particular, we estimate that 1.5 - 2.0% of objects randomly added to ACS images are misclassified as mergers due ...

  6. A new method to assign galaxy cluster membership using photometric redshifts

    CERN Document Server

    Castignani, Gianluca

    2016-01-01

    We introduce a new effective strategy to assign group and cluster membership probabilities $P_{mem}$ to galaxies using photometric redshift information. Large dynamical ranges both in halo mass and cosmic time are considered. The method takes the magnitude distribution of both cluster and field galaxies as well as the radial distribution of galaxies in clusters into account using a non-parametric formalism and relies on Bayesian inference to take photometric redshift uncertainties into account. We successfully test the method against 1,208 galaxy clusters within redshifts $z=0.05-2.55$ and masses $10^{13.29-14.80}~M_\\odot$ drawn from wide field simulated galaxy mock catalogs developed for the Euclid mission. Median purity $(55^{+17}_{-15})\\%$ and completeness $(95^{+5}_{-10})\\%$ are reached for galaxies brighter than 0.25$L_\\ast$ within $r_{200}$ of each simulated halo and for a statistical photometric redshift accuracy $\\sigma((z_s-z_p)/(1+z_s))=0.03$. The mean values $\\overline{\\mathsf{p}}=56\\%$ and $\\overl...

  7. Why do high-redshift galaxies show diverse gas-phase metallicity gradients?

    Science.gov (United States)

    Ma, Xiangcheng; Hopkins, Philip F.; Feldmann, Robert; Torrey, Paul; Faucher-Giguère, Claude-André; Kereš, Dušan

    2017-01-01

    Recent spatially resolved observations of galaxies at z ˜ 0.6-3 reveal that high-redshift galaxies show complex kinematics and a broad distribution of gas-phase metallicity gradients. To understand these results, we use a suite of high-resolution cosmological zoom-in simulations from the Feedback in Realistic Environments (FIRE) project, which include physically motivated models of the multi-phase ISM, star formation, and stellar feedback. Our simulations reproduce the observed diversity of kinematic properties and metallicity gradients, broadly consistent with observations at z ˜ 0-3. Strong negative metallicity gradients only appear in galaxies with a rotating disk, but not all rotationally supported galaxies have significant gradients. Strongly perturbed galaxies with little rotation always have flat gradients. The kinematic properties and metallicity gradient of a high-redshift galaxy can vary significantly on short time-scales, associated with starburst episodes. Feedback from a starburst can destroy the gas disk, drive strong outflows, and flatten a pre-existing negative metallicity gradient. The time variability of a single galaxy is statistically similar to the entire simulated sample, indicating that the observed metallicity gradients in high-redshift galaxies reflect the instantaneous state of the galaxy rather than the accretion and growth history on cosmological time-scales. We find weak dependence of metallicity gradient on stellar mass and specific star formation rate (sSFR). Low-mass galaxies and galaxies with high sSFR tend to have flat gradients, likely due to the fact that feedback is more efficient in these galaxies. We argue that it is important to resolve feedback on small scales in order to produce the diverse metallicity gradients observed.

  8. H0LiCOW VI. Testing the fidelity of lensed quasar host galaxy reconstruction

    CERN Document Server

    Ding, Xuheng; Treu, Tommaso; Suyu, Sherry H; Chen, Geoff C -F; Auger, Matthew W; Marshall, Philip J; Agnello, Adriano; Courbin, Frederic; Nierenberg, Anna M; Rusu, Cristian E; Sluse, Dominique; Sonnenfeld, Alessandro; Wong, Kenneth C

    2016-01-01

    The empirical correlation between the mass of a super-massive black hole (MBH) and its host galaxy properties is widely considered to be evidence of their co-evolution. A powerful way to test the co-evolution scenario and learn about the feedback processes linking galaxies and nuclear activity is to measure these correlations as a function of redshift. Unfortunately, currently MBH can only be estimated in active galaxies at cosmological distances. At these distances, bright active galactic nuclei (AGN) can outshine the host galaxy, making it extremely difficult to measure the host's luminosity. Strongly lensed AGNs provide in principle a great opportunity to improve the sensitivity and accuracy of the host galaxy luminosity measurements as the host galaxy is magnified and more easily separated from the point source, provided the lens model is sufficiently accurate. In order to measure the MBH-L correlation with strong lensing, it is necessary to ensure that the lens modelling is accurate, and that the host ga...

  9. Real or Interloper? The Redshift Likelihoods of Galaxies in the HUDF12

    CERN Document Server

    Pirzkal, Nor; Ryan, Russell; Coe, Dan; Malhotra, Sangeeta; Rhoads, James; Noeske, Kai

    2013-01-01

    In the absence of spectra, fitting template model spectra to observed photometric fluxes, known as Spectral Energy Distribution (SED) fitting, has become the workhorse for identifying high-z galaxies. In this paper, we present an analysis of the most recent and possibly most distant galaxies discovered in the Hubble Ultra Deep Field using a more robust method of redshift estimation based on Markov Chain Monte Carlo fitting (MCMC), rather than relying on the redshift of "best fit" models obtained using common chi^2 minimization techniques. The advantage of MCMC fitting is the ability to accurately estimate the probability density function of the redshift, as well as any other input model parameters, allowing us to derive accurate credible intervals by properly marginalizing over all other input model parameters. We apply our method to 13 recently identified sources and show that, despite claims based on chi^2 minimization, none of these sources can be securely ruled out as low redshift interlopers given the lo...

  10. Star formation trends in high-redshift galaxy surveys: the elephant or the tail?

    CERN Document Server

    Stringer, Martin; Frenk, Carlos S; Stark, Daniel P

    2010-01-01

    Star formation rate and accummulated stellar mass are two fundamental physical quantities that describe the evolutionary state of a forming galaxy. Two recent attempts to determine the relationship between these quantities, by interpreting a sample of star-forming galaxies at redshift of z~4, have led to opposite conclusions. We use a model galaxy population to investigate possible causes for this discrepancy and conclude that minor errors in the conversion from observables to physical quantities can lead to major misrepresentation when applied without awareness of sample selection. We also investigate, in a general way, the physical origin of the correlation between star formation rate and stellar mass within hierarchical galaxy formation theory.

  11. How Robust Are the Size Measurements of High-redshift Compact Galaxies?

    CERN Document Server

    Davari, Roozbeh; Peng, Chien Y; Huang, Song

    2014-01-01

    Massive quiescent galaxies at $z \\approx 2$ are apparently much more compact than galaxies of comparable mass today. How robust are these size measurements? We perform comprehensive simulations to determine possible biases and uncertainties in fitting single-component light distributions to real galaxies. In particular, we examine the robustness of the measurements of the luminosity, size, and other structural parameters. We devise simulations with increasing realism to systematically disentangle effects due to the technique (specifically using GALFIT) and the intrinsic structures of the galaxies. 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 $z \\approx 2$ 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 model...

  12. Stacking for machine learning redshifts applied to SDSS galaxies

    OpenAIRE

    Zitlau, Roman; Hoyle, Ben; Paech, Kerstin; Weller, Jochen; Rau, Markus Michael; Seitz, Stella

    2016-01-01

    We present an analysis of a general machine learning technique called 'stacking' for the estimation of photometric redshifts. Stacking techniques can feed the photometric redshift estimate, as output by a base algorithm, back into the same algorithm as an additional input feature in a subsequent learning round. We shown how all tested base algorithms benefit from at least one additional stacking round (or layer). To demonstrate the benefit of stacking, we apply the method to both unsupervised...

  13. Photometric Redshifts for High Resolution Radio Galaxies in the SuperCLASS Field

    Science.gov (United States)

    Manning, Sinclaire; Casey, Caitlin; Battye, Richard; Hales, Christopher A.; Chapman, Scott; Smail, Ian; SuperCLASS Team

    2017-01-01

    SuperCLASS (the Super-Cluster Assisted Shear Survey) is a deep, wide-area (~2 square degrees) extragalactic field with high resolution (0.1”) radio continuum coverage from e-MERLIN (Multi-Element Radio Linked Interferometer Network.) The combination of sensitivity and spatial resolution make e-MERLIN an ideal tool to trace spatially resolved star-formation in heavily obscured, dusty star-forming galaxies (DSFGs). Plus, thanks to the tight relationship between radio continuum and far-IR observations we have an observationally inexpensive and accurate method of mapping star formation density in distant galaxies. We present a photometric redshift catalog for DSFGs located in the SuperCLASS field. Multiwavelength photometric data was obtained with Subaru SuprimeCam (B,V,r,i,z) and photometric redshifts were generated using the public photometric redshift code, EAZY. With these redshifts we aim to conduct the first large sample morphological analysis of z~1-3 obscured galaxies. We plan to address two important questions: 1) Are the majority of obscured SFR>50 Msolar/yr galaxies driven by major collisions? and 2) do luminous active galactic nuclei (AGN) play a crucial role in the quenching of highly obscured star-formation? These photometric redshifts are crucial in determining the physical origins of our DSFG sample and to also conduct radio weak lensing experiments with the e-MERLIN dataset.

  14. Herschel-ATLAS: Properties of dusty massive galaxies at low and high redshifts

    CERN Document Server

    Rowlands, K; Dye, S; Aragón-Salamanca, A; Maddox, S; da Cunha, E; Smith, D J B; Bourne, N; Eales, S; Gomez, H L; Smail, I; Alpaslan, M; Clark, C J R; Driver, S; Ibar, E; Ivison, R J; Robotham, A; Smith, M W L; Valiante, E

    2014-01-01

    We present a comparison of the physical properties of a rest-frame $250\\mu$m selected sample of massive, dusty galaxies from $01$ SMGs have an average SFR of $390^{+80}_{-70}\\,$M$_\\odot$yr$^{-1}$ which is 120 times that of the low-redshift sample matched in stellar mass to the SMGs (SFR$=3.3\\pm{0.2}$ M$_\\odot$yr$^{-1}$). The SMGs harbour a substantial mass of dust ($1.2^{+0.3}_{-0.2}\\times{10}^9\\,$M$_\\odot$), compared to $(1.6\\pm0.1)\\times{10}^8\\,$M$_\\odot$ for low-redshift dusty galaxies. At low redshifts the dust luminosity is dominated by the diffuse ISM, whereas a large fraction of the dust luminosity in SMGs originates from star-forming regions. At the same dust mass SMGs are offset towards a higher SFR compared to the low-redshift H-ATLAS galaxies. This is not only due to the higher gas fraction in SMGs but also because they are undergoing a more efficient mode of star formation, which is consistent with their bursty star-formation histories. The offset in SFR between SMGs and low-redshift galaxies is s...

  15. MgII Absorption through Intermediate Redshift Galaxies

    CERN Document Server

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

    2005-01-01

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

  16. Apparent Clustering of Intermediate-redshift Galaxies as a Probe of Dark Energy

    CERN Document Server

    Matsubara, T; Matsubara, Takahiko; Szalay, Alexander S.

    2002-01-01

    We show the apparent redshift-space clustering of galaxies in redshift range of 0.2-0.4 provides surprisingly useful constraints on dark energy component in the universe, because of the right balance between the density of objects and the survey depth. We apply Fisher matrix analyses to the the Luminous Red Galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS), as a concrete example. Possible degeneracies in the evolution of the equation of state (EOS) and the other cosmological parameters are clarified.

  17. Simulating the [CII] emission of high redshift galaxies

    DEFF Research Database (Denmark)

    Pardos Olsen, Karen; Greve, Thomas Rodriguez; Narayanan, Desika;

    2016-01-01

    density. For the chemistry and radiative transfer, the photoionization code CLOUDY is implemented. I will show results for z=2 star-forming galaxies yet to be observed, as well as preliminary results for galaxies at z~6-7 where observations have presented contradictory detections and non......-detections of star-forming galaxies.......The fine structure line of [CII] at 158 microns can arise throughout the interstellar medium (ISM) and has been proposed as a tracer of star formation rate (SFR). But the origin of [CII] and how it depends on e.g. metallicity and radiation field of a galaxy remain uncertain.Simulating [CII] can...

  18. Redshift and luminosity evolution of the intrinsic alignments of galaxies in Horizon-AGN

    Science.gov (United States)

    Chisari, N.; Laigle, C.; Codis, S.; Dubois, Y.; Devriendt, J.; Miller, L.; Benabed, K.; Slyz, A.; Gavazzi, R.; Pichon, C.

    2016-09-01

    Intrinsic galaxy shape and angular momentum alignments can arise in cosmological large-scale structure due to tidal interactions or galaxy formation processes. Cosmological hydrodynamical simulations have recently come of age as a tool to study these alignments and their contamination to weak gravitational lensing. We probe the redshift and luminosity evolution of intrinsic alignments in Horizon-AGN between z = 0 and 3 for galaxies with an r-band absolute magnitude of Mr ≤ -20. Alignments transition from being radial at low redshifts and high luminosities, dominated by the contribution of ellipticals, to being tangential at high redshift and low luminosities, where discs dominate the signal. This cannot be explained by the evolution of the fraction of ellipticals and discs alone: intrinsic evolution in the amplitude of alignments is necessary. The alignment amplitude of elliptical galaxies alone is smaller in amplitude by a factor of ≃2, but has similar luminosity and redshift evolution as in current observations and in the non-linear tidal alignment model at projected separations of ≳1 Mpc. Alignments of discs are null in projection and consistent with current low-redshift observations. The combination of the two populations yields an overall amplitude a factor of ≃4 lower than observed alignments of luminous red galaxies with a steeper luminosity dependence. The restriction on accurate galaxy shapes implies that the galaxy population in the simulation is complete only to Mr ≤ -20. Higher resolution simulations will be necessary to avoid extrapolation of the intrinsic alignment predictions to the range of luminosities probed by future surveys.

  19. The EGNoG Survey: Molecular Gas in Intermediate-Redshift Star-Forming Galaxies

    CERN Document Server

    Bauermeister, Amber; Bolatto, Alberto D; Bureau, Martin; Leroy, Adam; Ostriker, Eve; Teuben, Peter J; Wong, Tony; Wright, Melvyn C H

    2013-01-01

    We present the Evolution of molecular Gas in Normal Galaxies (EGNoG) survey, an observational study of molecular gas in 31 star-forming galaxies from z=0.05 to z=0.5, with stellar masses of (4-30)x10^10 M_Sun and star formation rates of 4-100 M_Sun yr^-1. This survey probes a relatively un-observed redshift range in which the molecular gas content of galaxies is expected to have evolved significantly. To trace the molecular gas in the EGNoG galaxies, we observe the CO(1-0) and CO(3-2) rotational lines using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We detect 24 of 31 galaxies and present resolved maps of 10 galaxies in the lower redshift portion of the survey. We use a bimodal prescription for the CO to molecular gas conversion factor, based on specific star formation rate, and compare the EGNoG galaxies to a large sample of galaxies assembled from the literature. We find an average molecular gas depletion time of 0.76 \\pm 0.54 Gyr for normal galaxies and 0.06 \\pm 0.04 Gyr for star...

  20. Galaxy Mergers and Dark Matter Halo Mergers in LCDM: Mass, Redshift, and Mass-Ratio Dependence

    CERN Document Server

    Stewart, Kyle R; Barton, Elizabeth J; Wechsler, Risa H

    2008-01-01

    We employ a high-resolution LCDM N-body simulation to present merger rate predictions for dark matter halos and investigate how common merger-related observables for galaxies--such as close pair counts, starburst counts, and the morphologically disturbed fraction--likely scale with luminosity, stellar mass, merger mass ratio, and redshift from z=0 to z=4. We provide a simple 'universal' fitting formula that describes our derived merger rates for dark matter halos a function of dark halo mass, merger mass ratio, and redshift, and go on to predict galaxy merger rates using number density-matching to associate halos with galaxies. For example, we find that the instantaneous merger rate of m/M>0.3 mass ratio events into typical L > f L* galaxies follows the simple relation dN/dt=0.03(1+f)(1+z)^2.1 Gyr^-1. Despite the rapid increase in merger rate with redshift, only a small fraction of >0.4 L* high-redshift galaxies (~3% at z=2) should have experienced a major merger (m/M >0.3) in the very recent past (t0.3) in t...

  1. High-Redshift Galaxy Kinematics: Constraints on Models of Disk Formation

    CERN Document Server

    Robertson, Brant E

    2008-01-01

    Integral field spectroscopy of galaxies at redshift z~2 has revealed a population of early-forming, rotationally-supported disks. These high-redshift systems provide a potentially important clue to the formation processes that build disk galaxies in the universe. A particularly well-studied example is the z=2.38 galaxy BzK-15504, which was shown by Genzel et al. (2006) to be a rotationally supported disk despite the fact that its high star formation rate and short gas consumption timescale require a very rapid acquisition of mass. Previous kinematical analyses have suggested that z~2 disk galaxies like BzK-15504 did not form through mergers because their line-of-sight velocity fields display low levels of asymmetry. We perform the same kinematical analysis on a set of simulated disk galaxies formed in gas-rich mergers of the type that may be common at high redshift, and show that the remnant disks display low velocity field asymmetry and satisfy the criteria that have been used to classify high-redshift galax...

  2. The Advanced Camera for Surveys General Catalog: A High Redshift Galaxy Morphology Catalog

    Science.gov (United States)

    Griffith, Roger; Newman, J.; Cooper, M.; Stern, D.; Moustakas, L.; Davis, M.

    2009-05-01

    We use publicly available data obtained with the Advanced Camera for Surveys (ACS) instrument on the Hubble Space Telescope to construct the ACS General Catalog (ACS-GC). The ACS-GC includes over 370,000 astronomical sources (stars + galaxies) derived from the AEGIS, COSMOS, GEMS, and GOODS surveys. We include publicly available redshifts from the DEEP2, COMBO-17, TKRS, PEARS and zCOSMOS surveys to supply redshifts for a considerable fraction ( 52%) of the imaging sample. GALAPAGOS was used to construct photometric (SExtractor) and morphological (GALFIT) catalogs. The morphological analysis assumes a single Sersic model for each object to derive quantitative structural parameters. Galaxy Zoo will measure visual morphologies for 200,000 of these galaxies. The ACS-GC includes color images, GALFIT residual images, a galaxy atlas, and a photometry + morphology + redshift catalog. We use these data to investigate the size-redshift relationship for both early and late-type galaxies out to z 1. The entire data set will be made publicly available through the NASA Extragalactic Database (NED) and LEVEL5.

  3. The impact of nebular emission on the broadband fluxes of high-redshift galaxies

    CERN Document Server

    Zackrisson, E; Leitet, E

    2008-01-01

    A substantial fraction of the light emitted from young or star-forming galaxies at ultraviolet to near-infrared wavelengths comes from the ionized interstellar medium in the form of emission lines and a nebular continuum. At high redshifts, star formation rates are on average higher and stellar populations younger than in the local Universe. Both of these effects act to boost the impact of nebular emission on the overall spectrum of galaxies. Even so, the broadband fluxes and colours of high-redshift galaxies are routinely analyzed under the assumption that the light observed originates directly from stars. Here, we assess the impact of nebular emission on broadband fluxes in Johnson/Cousins BVRIJHK, Sloan Digital Sky Survey griz and Spitzer IRAC/MIPS filters as a function of observed redshift (up to z=15) for galaxies with different star formation histories. We find that nebular emission may account for a non-negligible fraction of the light received from high-redshift galaxies. The ages and masses inferred ...

  4. H0LiCOW. VI. Testing the fidelity of lensed quasar host galaxy reconstruction

    Science.gov (United States)

    Ding, Xuheng; Liao, Kai; Treu, Tommaso; Suyu, Sherry H.; Chen, Geoff C.-F.; Auger, Matthew W.; Marshall, Philip J.; Agnello, Adriano; Courbin, Frederic; Nierenberg, Anna M.; Rusu, Cristian E.; Sluse, Dominique; Sonnenfeld, Alessandro; Wong, Kenneth C.

    2017-03-01

    The empirical correlation between the mass of a supermassive black hole (M_BH) and its host galaxy properties is widely considered to be an evidence of their co-evolution. A powerful way to test the co-evolution scenario and learn about the feedback processes linking galaxies and nuclear activity is to measure these correlations as a function of redshift. Unfortunately, currently M_BH can only be estimated in active galaxies at cosmological distances. At these distances, bright active galactic nuclei (AGNs) can outshine the host galaxy, making it extremely difficult to measure the host's luminosity. Strongly lensed AGNs provide in principle a great opportunity to improve the sensitivity and accuracy of the host galaxy luminosity measurements as the host galaxy is magnified and more easily separated from the point source, provided the lens model is sufficiently accurate. In order to measure the M_BH-L correlation with strong lensing, it is necessary to ensure that the lens modelling is accurate, and that the host galaxy luminosity can be recovered to at least a precision and accuracy better than that of the typical M_BH measurement. We carry out extensive and realistic simulations of deep Hubble Space Telescope observations of lensed AGNs obtained by our collaboration. We show that the host galaxy luminosity can be recovered with better accuracy and precision than the typical uncertainty in M_BH(∼0.5 dex) for hosts as faint as 2-4 mag dimmer than the AGN itself. Our simulations will be used to estimate bias and uncertainties in the actual measurements to be presented in a future paper.

  5. A physical model for the evolving UV luminosity function of high redshift galaxies and their contribution to the cosmic reionization

    CERN Document Server

    Cai, Zhen-Yi; Bressan, Alessandro; De Zotti, Gianfranco; Negrello, Mattia; Danese, Luigi

    2014-01-01

    [Abridged] We present a physical model for the evolution of the ultraviolet (UV) luminosity function (LF) of high-z galaxies taking into account in a self-consistent way their chemical evolution and the associated evolution of dust extinction. The model yields good fits of the UV and Lyman-alpha LFs at z>~2. The weak evolution of both LFs between z=2 and z=6 is explained as the combined effect of the negative evolution of the halo mass function, of the increase with redshift of the star formation efficiency, and of dust extinction. The slope of the faint end of the UV LF is found to steepen with increasing redshift, implying that low luminosity galaxies increasingly dominate the contribution to the UV background at higher and higher redshifts. The observed range of UV luminosities at high-z implies a minimum halo mass capable of hosting active star formation M_crit <~ 10^9.8 M_odot, consistent with the constraints from hydrodynamical simulations. From fits of Lyman-alpha LFs plus data on the luminosity dep...

  6. The Accelerated Build-up of the Red Sequence in High Redshift Galaxy Clusters

    CERN Document Server

    Cerulo, P; Lidman, C; Demarco, R; Huertas-Company, M; Mei, S; Sánchez-Janssen, R; Barrientos, L F; Muñoz, R P

    2016-01-01

    We analyse the evolution of the red sequence in a sample of galaxy clusters at redshifts $0.8 11.5$) red sequence galaxies in the WINGS clusters, which do not include only the brightest cluster galaxies and which are not present in the HCS clusters, suggesting that they formed at epochs later than $z=0.8$. The comparison with the luminosity distribution of a sample of passive red sequence galaxies drawn from the COSMOS/UltraVISTA field in the photometric redshift range $0.8

  7. The K20 survey. IV. The redshift distribution of Ks<20 galaxies a test of galaxy formation models

    CERN Document Server

    Cimatti, A; Mignoli, M; Daddi, E; Menci, N; Poli, F; Fontana, A; Renzini, A; Zamorani, G; Broadhurst, T J; Cristiani, S; D'Odorico, S; Giallongo, E; Gilmozzi, R

    2002-01-01

    We present the redshift distribution of a complete sample of 480 galaxies with Ks1 and z>1.5 respectively. A ``blind'' comparison is made with the predictions of a set of the most recent LambdaCDM hierarchical merging and pure luminosity evolution (PLE) models. The hierarchical merging models overpredict and underpredict the number of galaxies at low-z and high-z respectively, whereas the PLE models match the median redshift and the low-z distribution, still being able to follow the high-z tail of N(z). We briefly discuss the implications of this comparison and the possible origins of the observed discrepancies. We make the redshift distribution publicly available.

  8. Deep Ly alpha imaging of two z=2.04 GRB host galaxy fields

    DEFF Research Database (Denmark)

    Fynbo, J.P.U.; Møller, Per; Thomsen, Bente

    2002-01-01

    We report on the results of deep narrow-band Lyalpha and broad-band U and I imaging of the fields of two Gamma-Ray bursts at redshift z = 2.04 (GRB 000301C and GRB 000926). We find that the host galaxy of GRB 000926 is an extended (more than 2 arcsec), strong Lyalpha emitter with a rest-frame equ......We report on the results of deep narrow-band Lyalpha and broad-band U and I imaging of the fields of two Gamma-Ray bursts at redshift z = 2.04 (GRB 000301C and GRB 000926). We find that the host galaxy of GRB 000926 is an extended (more than 2 arcsec), strong Lyalpha emitter with a rest...

  9. Deep Ly alpha imaging of two z=2.04 GRB host galaxy fields

    DEFF Research Database (Denmark)

    Fynbo, J.P.U.; Møller, Per; Thomsen, Bente

    2002-01-01

    We report on the results of deep narrow-band Lyalpha and broad-band U and I imaging of the fields of two Gamma-Ray bursts at redshift z = 2.04 (GRB 000301C and GRB 000926). We find that the host galaxy of GRB 000926 is an extended (more than 2 arcsec), strong Lyalpha emitter with a rest-frame equ......We report on the results of deep narrow-band Lyalpha and broad-band U and I imaging of the fields of two Gamma-Ray bursts at redshift z = 2.04 (GRB 000301C and GRB 000926). We find that the host galaxy of GRB 000926 is an extended (more than 2 arcsec), strong Lyalpha emitter with a rest...

  10. Directly Imaging Damped Ly-Alpha Galaxies at Redshifts Greater Than 2. III: The Star Formation Rates of Neutral Gas Reservoirs at Redshifts of Approximately 2.7

    Science.gov (United States)

    Fumagalli, Michele; OMeara, John M.; Prochaska, J. Xavier; Rafelski, Marc; Kanekar, Nissim

    2014-01-01

    We present results from a survey designed to probe the star formation properties of 32 damped Ly alpha systems (DLAs) at redshifts of approximately 2.7. By using the "double-DLA" technique that eliminates the glare of the bright background quasars, we directly measure the rest-frame FUV flux from DLAs and their neighbouring galaxies. At the position of the absorbing gas, we place stringent constraints on the unobscured star formation rates (SFRs) of DLAs to 2 sigma limits of psi less than 0.09-0.27 solar mass yr(exp -1), corresponding to SFR surface densities sigma(sub sfr) less than 10(exp -2.6)-10(exp -1.5) solar mass yr(exp -1) kpc(exp -2). The implications of these limits for the star formation law, metal enrichment, and cooling rates of DLAs are examined. By studying the distribution of impact parameters as a function of SFRs for all the galaxies detected around these DLAs, we place new direct constraints on the bright end of the UV luminosity function of DLA hosts. We find that less than or equal to 13% of the hosts have psi greater than or equal to 2 solar mass yr(exp -1) at impact parameters b(sub dla) less than or equal to (psi/solar mass yr(exp -1))(exp 0.8) + 6 kpc, differently from current samples of confirmed DLA galaxies. Our observations also disfavor a scenario in which the majority of DLAs arise from bright LBGs at distances 20 less than or equal to b(sub dla) less than 100 kpc. These new findings corroborate a picture in which DLAs do not originate from highly star forming systems that are coincident with the absorbers, and instead suggest that DLAs are associated with faint, possibly isolated, star-forming galaxies. Potential shortcomings of this scenario and future strategies for further investigation are discussed.

  11. Redshifts for a sample of fainter galaxies in the first CfA survey slice

    Science.gov (United States)

    Thorstensen, J. R.; Wegner, G. A.; Hamwey, R.; Boley, F.; Geller, M. J.

    1989-01-01

    Redshifts were measured for 93 of the 94 galaxies in the Zwicky-Nilson merged catalog with the value of m(B/01) between 15.5 and 15.7 and with right ascension alpha between 8(h) and 17(h) and declination delta between 29 and 30 deg. This region is within the one covered by the first slice of the CfA (Center for Astrophysics) survey. The galaxies reinforce features already visible in the earlier survey.

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

    Science.gov (United States)

    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.

  13. A low-redshift low luminosity QSO sample: Comparison with NUGA galaxies and PG QSOs and first interferometric images of three sample members

    CERN Document Server

    Moser, Lydia; Fischer, Sebastian; Busch, Gerold; Valencia-S., Monica; Eckart, Andreas; Krips, Melanie; Scharwaechter, Julia

    2013-01-01

    The low luminosity QSO (LLQSO) sample consists of type 1 active galactic nuclei (AGN) up to a redshift of z=0.06 in the Hamburg/ESO QSO survey. Its purpose is to study how the brightest AGN in the nearby universe evolve with respect to AGN activity and host properties as a function of redshift. We show that our sample lies well between the NUclei of GAlaxies (NUGA) sample and the Palomar Green (PG) QSO sample in terms of redshift, gas masses and luminosities and seems to connect them. The continuous growth in mass, luminosity and, linked to this, the AGN activity over the samples has either a statistical reason or is indicative of an evolutionary link between the different populations and might be related to cosmic downsizing. In addition, we present first results of our observations of three galaxies from our sample with the Submillimeter Array (SMA).

  14. Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies

    Science.gov (United States)

    Izotov, Y. I.; Schaerer, D.; Thuan, T. X.; Worseck, G.; Guseva, N. G.; Orlitová, I.; Verhamme, A.

    2016-10-01

    Following our first detection reported in Izotov et al., we present the detection of Lyman continuum (LyC) radiation of four other compact star-forming galaxies observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope. These galaxies, at redshifts of z ˜ 0.3, are characterized by high emission-line flux ratios [O III] λ5007/[O II] λ3727 ≳ 5. The escape fractions of the LyC radiation fesc(LyC) in these galaxies are in the range of ˜6-13 per cent, the highest values found so far in low-redshift star-forming galaxies. Narrow double-peaked Ly α emission lines are detected in the spectra of all four galaxies, compatible with predictions for LyC leakers. We find escape fractions of Ly α, fesc(Ly α) ˜ 20-40 per cent, among the highest known for Ly α emitting galaxies. Surface brightness profiles produced from the COS acquisition images reveal bright star-forming regions in the centre and exponential discs in the outskirts with disc scalelengths α in the range ˜0.6-1.4 kpc. Our galaxies are characterized by low metallicity, ˜1/8-1/5 solar, low stellar mass ˜(0.2-4) × 109 M⊙, high star formation rates, SFR ˜ 14-36 M⊙ yr-1, and high SFR densities, Σ ˜ 2-35 M⊙ yr-1 kpc-2. These properties are comparable to those of high-redshift star-forming galaxies. Finally, our observations, combined with our first detection reported in Izotov et al., reveal that a selection for compact star-forming galaxies showing high [O III] λ5007/[O II] λ3727 ratios appears to pick up very efficiently sources with escaping LyC radiation: all five of our selected galaxies are LyC leakers.

  15. Redshift

    CERN Document Server

    Clark, Stuart

    1997-01-01

    The light emitted by celestial objects can have its wavelength "stretched" in different ways before it is observed by astronomers. These stretching phenomena are collectively called "redshift". They influence virtually all aspects of astronomy and even underpin the "Big Bang" theory of the creation of the universe. This book details the types of redshift and explains their myriad of uses. It begins by introducing the nature of light and the problems involved in measuring its properties. After explaining the redshift phenomena and their uses, the book touches on the age and size of the universe; two subjects embroiled in controversy because of our current interpretation of the redshift. Less conventional theories are then expressed. As a by-product of the explanation of redshift, the book offers the reader a basic understanding of Einstein's theory of relativity. Mathematical treatments of the concepts introduced in the text are boxed off and should not detract from the book's readibility, but allow it to be u...

  16. Spectroscopic Properties of Star-Forming Host Galaxies and Type Ia Supernova Hubble Residuals in a Nearly Unbiased Sample

    Energy Technology Data Exchange (ETDEWEB)

    D' Andrea, Chris B. [Univ. of Pennsylvania, Philadelphia, PA (United States); et al.

    2011-12-20

    We examine the correlation between supernova host galaxy properties and their residuals on the Hubble diagram. We use supernovae discovered during the Sloan Digital Sky Survey II - Supernova Survey, and focus on objects at a redshift of z < 0.15, where the selection effects of the survey are known to yield a complete Type Ia supernova sample. To minimize the bias in our analysis with respect to measured host-galaxy properties, spectra were obtained for nearly all hosts, spanning a range in magnitude of -23 < M_r < -17. In contrast to previous works that use photometric estimates of host mass as a proxy for global metallicity, we analyze host-galaxy spectra to obtain gas-phase metallicities and star-formation rates from host galaxies with active star formation. From a final sample of ~ 40 emission-line galaxies, we find that light-curve corrected Type Ia supernovae are ~ 0.1 magnitudes brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (> 3{\\sigma}) correlation between the Hubble residuals of Type Ia supernovae and the specific star-formation rate of the host galaxy. We comment on the importance of supernova/host-galaxy correlations as a source of systematic bias in future deep supernova surveys.

  17. On the mass-metallicity relation, velocity dispersion and gravitational well depth of GRB host galaxies

    CERN Document Server

    Arabsalmani, Maryam; Fynbo, Johan P U; Christensen, Lise; Freudling, Wolfram; Savaglio, Sandra; Zafar, Tayyaba

    2014-01-01

    We analyze a sample of 16 absorption systems intrinsic to long duration GRB host galaxies at $z \\gtrsim 2$ for which the metallicities are known. We compare the relation between the metallicity and cold gas velocity width for this sample to that of the QSO-DLAs, and find complete agreement. We then compare the redshift evolution of the mass-metallicity relation of our sample to that of QSO-DLAs and find that also GRB hosts favour a late onset of this evolution, around a redshift of $\\approx 2.6$. We compute predicted stellar masses for the GRB host galaxies using the prescription determined from QSO-DLA samples and compare the measured stellar masses for the four hosts where stellar masses have been determined from SED fits. We find excellent agreement and conclude that, on basis of all available data and tests, long duration GRB-DLA hosts and intervening QSO-DLAs are consistent with being drawn from the same underlying population. GRB host galaxies and QSO-DLAs are found to have different impact parameter di...

  18. Are High-redshift Galaxies Hot? Temperature of z > 5 Galaxies and Implications for Their Dust Properties

    Science.gov (United States)

    Faisst, Andreas L.; Capak, Peter L.; Yan, Lin; Pavesi, Riccardo; Riechers, Dominik A.; Barišić, Ivana; Cooke, Kevin C.; Kartaltepe, Jeyhan S.; Masters, Daniel C.

    2017-09-01

    Recent studies have found a significant evolution and scatter in the relationship between the UV spectral slope (β UV) and the infrared excess (IRX; L IR/L UV) at z > 4, suggesting different dust properties of these galaxies. The total far-infrared (FIR) luminosity is key for this analysis, but it is poorly constrained in normal (main-sequence) star-forming z > 5 galaxies, where often only one single FIR point is available. To better inform estimates of the FIR luminosity, we construct a sample of local galaxies and three low-redshift analogues of z > 5 systems. The trends in this sample suggest that normal high-redshift galaxies have a warmer infrared (IR) spectral energy distribution (SED) compared to average z relation at z > 5. Despite this, some galaxies still fall below the minimum IRX‑β relation derived with standard dust cloud models. We propose that radiation pressure in these highly star-forming galaxies causes a spatial offset between dust clouds and young star-forming regions within the lifetime of O/B stars. These offsets change the radiation balance and create viewing-angle effects that can change UV colors at fixed IRX. We provide a modified model that can explain the location of these galaxies on the IRX‑β diagram.

  19. Dark-ages reionization and galaxy formation simulation--VII. The sizes of high-redshift galaxies

    CERN Document Server

    Liu, Chuanwu; Poole, Gregory; Angel, Paul; Duffy, Alan; Geil, Paul; Mesinger, Andrei; Wyithe, Stuart

    2016-01-01

    We investigate high-redshift galaxy sizes using a semi-analytic model constructed for the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulation project. Our fiducial model, including strong feedback from supernovae and photoionization background, accurately reproduces the evolution of the stellar mass function and luminosity function. Using this model, we study the size--luminosity relation of galaxies and find that the effective radius scales with UV luminosity as $R_\\mathrm{e}\\propto L^{0.25}$ at $z{\\sim}5$--$9$. We show that recently discovered very luminous galaxies at $z{\\sim}7$ (Bowler et al. 2016) and $z{\\sim}11$ (Oesch et al. 2016) lie on our predicted size--luminosity relations. We find that a significant fraction of galaxies at $z>6$ will not be resolved by JWST, but GMT will have the ability to resolve all galaxies in haloes above the atomic cooling limit. We show that our fiducial model successfully reproduces the redshift evolution of average galaxy sizes at $z>5$. We ...

  20. Very Strong Emission-Line Galaxies in the WISP Survey and Implications for High-Redshift Galaxies

    CERN Document Server

    Atek, H; Scarlata, C; Malkan, M; McCarthy, P; Teplitz, H; Henry, A; Colbert, J; Bridge, C; Bunker, A J; Dressler, A; Fosbury, R; Hathi, N P; Martin, C; Ross, N R; Shim, H

    2011-01-01

    The WFC3 Infrared Spectroscopic Parallel Survey (WISP) uses the Hubble Space Telescope (HST) infrared grism capabilities to obtain slitless spectra of thousands of galaxies over a wide redshift range including the peak of star formation history of the Universe. We select a population of very strong emission-line galaxies with rest-frame equivalent widths higher than 200 A. A total of 176 objects are found over the redshift range 0.35 < z < 2.3 in the 180 arcmin^2 area we analyzed so far. After estimating the AGN fraction in the sample, we show that this population consists of young and low-mass starbursts with higher specific star formation rates than normal star-forming galaxies at any redshift. After spectroscopic follow-up of one of these galaxies with Keck/LRIS, we report the detection at z = 0.7 of an extremely metal-poor galaxy with 12+Log(O/H)= 7.47 +- 0.11. The nebular emission-lines can substantially affect the broadband flux density with a median brightening of 0.3 mag, with examples producing...

  1. Galaxy power spectrum in redshift space: combining perturbation theory with the halo model

    CERN Document Server

    Okumura, Teppei; Seljak, Uros; Vlah, Zvonimir; Desjacques, Vincent

    2015-01-01

    Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution and large virial velocities inside halos, a phenomenon known as the Finger-of-God effect. We present a model for the galaxy power spectrum of in which we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to 1- and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and ...

  2. Direct determination of oxygen abundances in line emitting star-forming galaxies at intermediate redshift

    CERN Document Server

    Pérez, José M; Díaz, Ángeles I; Koo, David C; Willmer, Christopher N

    2015-01-01

    We present a sample of 22 blue ($(B-V)_{AB}<0.45$), luminous ($M_{B,AB}<-18.9$), metal-poor galaxies in the $0.69redshift range, selected from the DEEP2 galaxy redshift survey. Their spectra contain the $[OIII]\\lambda4363$ auroral line, the $[OII]\\lambda \\lambda3726,3729$ doublet and the strong nebular $[OIII]\\lambda \\lambda 4959,5007$ emission lines. The ionised gas-phase oxygen abundances of these galaxies lie between $7.62<12+\\log O/H < 8.19$, i.e. between $1/10 Z_{\\odot}$ and $1/3 Z_{\\odot}$. We find that galaxies in our sample have comparable metallicities to other intermediate-redshift samples, but are more metal poor than local systems of similar B-band luminosities and star formation activity. The galaxies here show similar properties to the "green peas" discovered at $z\\simeq 0.2 - 0.3$ though our galaxies tend to be slightly less luminous.

  3. Autofib Redshift Survey; 2, The Evolution of the Galaxy Luminosity Function by Spectral Type

    CERN Document Server

    Heyl, J S; Ellis, Richard S; Broadhurst, T J; Heyl, Jeremy; Colless, Matthew; Ellis, Richard S.; Broadhurst, Tom

    1996-01-01

    We determine the evolution of the galaxy luminosity function (LF) as a function of spectral type using the Autofib redshift survey, a compendium of over 1700 galaxy redshifts in various magnitude-limited samples spanning b_J=11.5-24.0. To carry out this analysis we have developed a cross-correlation technique which classifies faint galaxy spectra into one of six types based on local galaxy templates. Tests and simulations show that this technique yields classifications correct to within one type for more than 90% of the galaxies in our sample. We have also developed extensions of the step-wise maximum likelihood method and the STY parametric method for estimating LFs which are applicable to recovering an evolving LF from multiple samples. We find that: (i) The spectra and LF of E/S0 galaxies show no appreciable evolution out to at least z ~ 0.5. (ii) Early-type spirals show modest evolution, characterised by a gradual steepening of the faint end of their LF with redshift. (iii) Out to z ~ 0.5, the overall evo...

  4. VizieR Online Data Catalog: Host galaxies of Superluminous Supernovae (Angus+, 2016)

    Science.gov (United States)

    Angus, C. R.; Levan, A. J.; Perley, D. A.; Tanvir, N. R.; Lyman, J. D.; Stanway, E. R.; Fruchter, A. S.

    2016-11-01

    Here we use nIR and rest-frame UV observations of a sample of 21 SLSN host galaxies, within a redshift range of 0.019 SCP 06F6). This HST sample (programme GO-13025; PI: Levan) comprised 21 targets, based on the sample of Neill et al. (2011ApJ...727...15N), supplemented with luminous SNe from the literature (up to 2012 Jan). (6 data files).

  5. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Star formation history of passive red galaxies

    Science.gov (United States)

    Siudek, M.; Małek, K.; Scodeggio, M.; Garilli, B.; Pollo, A.; Haines, C. P.; Fritz, A.; Bolzonella, M.; de la Torre, S.; Granett, B. R.; Guzzo, L.; Abbas, U.; Adami, C.; Bottini, D.; Cappi, A.; Cucciati, O.; De Lucia, G.; Davidzon, I.; Franzetti, P.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Marchetti, A.; Marulli, F.; Polletta, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Arnouts, S.; Bel, J.; Branchini, E.; Ilbert, O.; Gargiulo, A.; Moscardini, L.; Takeuchi, T. T.; Zamorani, G.

    2017-01-01

    Aims: We trace the evolution and the star formation history of passive red galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). The detailed spectral analysis of stellar populations of intermediate-redshift passive red galaxies allows the build up of their stellar content to be followed over the last 8 billion years. Methods: We extracted a sample of passive red galaxies in the redshift range 0.4 relation for intermediate-redshift passive red galaxies. Results: We find that at z 1 stellar populations in low-mass passive red galaxies are younger than in high-mass passive red galaxies, similar to what is observed at the present epoch. Over the full analyzed redshift range 0.4 relations of D4000 and HδA with stellar mass has not changed significantly with redshift. Assuming a single burst formation, this implies that high-mass passive red galaxies formed their stars at zform 1.7, while low-mass galaxies formed their main stellar populations more recently, at zform 1. The consistency of these results, which were obtained using two independent estimators of the formation redshift (D4000 and HδA), further strengthens a scenario in which star formation proceeds from higher to lower mass systems as time passes, i.e., what has become known as the downsizing picture. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope

  6. Parsec-scale H I absorption structure in a low-redshift galaxy seen against a compact symmetric object

    Science.gov (United States)

    Biggs, A. D.; Zwaan, M. A.; Hatziminaoglou, E.; Péroux, C.; Liske, J.

    2016-11-01

    We present global VLBI observations of the 21-cm transition of atomic hydrogen seen in absorption against the radio source J0855+5751. The foreground absorber (SDSS J085519.05+575140.7) is a dwarf galaxy at z = 0.026. As the background source is heavily resolved by VLBI, the data allow us to map the properties of the foreground H I gas with a spatial resolution of 2 pc. The absorbing gas corresponds to a single coherent structure with an extent >35 pc, but we also detect significant and coherent variations, including a change in the H I optical depth by a factor of 5 across a distance of ≲ 6 pc. The large size of the structure provides support for the Heiles & Troland model of the interstellar medium, as well as its applicability to external galaxies. The large variations in H I optical depth also suggest that caution should be applied when interpreting TS measurements from radio-detected DLAs. In addition, the distorted appearance of the background radio source is indicative of a strong jet-cloud interaction in its host galaxy. We have measured its redshift (z = 0.541 86) using optical spectroscopy on the William Herschel Telescope and this confirms that J0855+5751 is an FR II radio source with a physical extent of compact symmetric object. These sources often show absorption associated with the host galaxy and we suggest that both H I and OH should be searched for in J0855+5751.

  7. The physical properties of AGN host galaxies as a probe of SMBH feeding mechanisms

    CERN Document Server

    Gatti, M; Menci, N; Bongiorno, A; Fiore, F

    2014-01-01

    Using a state-of-the-art semi analytic model (SAM) for galaxy formation, we have investigated the statistical effects of assuming two different mechanisms for triggering AGN activity on the properties of AGN host galaxies. We have considered a first accretion mode where AGN activity is triggered by disk instabilities (DI) in isolated galaxies, and a second feeding mode where such an activity is triggered by galaxy mergers and fly-by events (interactions, IT). We obtained the following results:i) for hosts with $M_* \\lesssim 10^{11} M_{\\bigodot}$, both DI and IT modes are able to account for the observed AGN hosts stellar mass function; for more massive hosts, the DI scenario predicts a lower space density than the IT model, lying below the observational estimates for z>0.8.ii) The analysis of the color-magnitude diagram (CMD) of AGN hosts for redshift z < 1.5 can provide a good observational test to effectively discriminate between the DI and IT mode, since DIs are expected to yield AGN host galaxy colors ...

  8. Dusty Star-Forming Galaxies at High Redshift

    CERN Document Server

    Casey, Caitlin M; Cooray, Asantha

    2014-01-01

    Far-infrared and submillimeter wavelength surveys have now established the important role of dusty, star-forming galaxies (DSFGs) in the assembly of stellar mass and the evolution of massive galaxies in the Universe. The brightest of these galaxies have infrared luminosities in excess of 10$^{13}$ L$_{\\odot}$ with implied star-formation rates of thousands of solar masses per year. They represent the most intense starbursts in the Universe, yet many are completely optically obscured. Their easy detection at submm wavelengths is due to dust heated by ultraviolet radiation of newly forming stars. When summed up, all of the dusty, star-forming galaxies in the Universe produce an infrared radiation field that has an equal energy density as the direct starlight emission from all galaxies visible at ultraviolet and optical wavelengths. The bulk of this infrared extragalactic background light emanates from galaxies as diverse as gas-rich disks to mergers of intense starbursting galaxies. Major advances in far-infrare...

  9. Spatially Resolved Velocity Maps of Halo Gas Around Two Intermediate-redshift Galaxies

    CERN Document Server

    Chen, Hsiao-Wen; Sharon, Keren; Johnson, Sean D; Nair, Preethi; Liang, Cameron J

    2013-01-01

    Absorption-line spectroscopy of multiply-lensed QSOs near a known foreground galaxy provides a unique opportunity to go beyond the traditional one-dimensional application of QSO probes and establish a crude three-dimensional (3D) map of halo gas around the galaxy that records the line-of-sight velocity field at different locations in the gaseous halo. Two intermediate-redshift galaxies are targeted in the field around the quadruply-lensed QSO HE0435-1223 at redshift z=1.689, and absorption spectroscopy along each of the lensed QSOs is carried out in the vicinities of these galaxies. One galaxy is a typical, star-forming L* galaxy at z=0.4188 and projected distance of rho=50 kpc from the lensing galaxy. The other is a super-L* barred spiral at z=0.7818 and rho=33 kpc. Combining known orientations of the quadruply-lensed QSO to the two foreground galaxies with the observed MgII absorption profiles along individual QSO sightlines has for the first time led to spatially resolved kinematics of tenuous halo gas on ...

  10. A COMPACT GROUP OF GALAXIES AT Z = 2.48 HOSTING AN AGN-DRIVEN OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Hsin-Yi [Gemini Observatory, 670 N Aohoku Place, Hilo, HI 96720 (United States); Stockton, Alan, E-mail: jshih@gemini.edu, E-mail: stockton@ifa.hawaii.edu [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    2015-12-10

    We present observations of a remarkable compact group of galaxies at z = 2.48. Four galaxies, all within 40 kpc of each other, surround a powerful high-redshift radio source. This group comprises two compact red passive galaxies and a pair of merging galaxies. One of the red galaxies, with an apparent stellar mass of 3.6 × 10{sup 11}M{sub ⊙} and an effective radius of 470 pc, is one of the most extreme examples of a massive quiescent compact galaxy found so far. One of the pair of merging galaxies hosts the active galactic nucleus (AGN) producing the large powerful radio structure. The merger is massive and enriched, consistent with the mass–metallicity relation expected at this redshift. Close to the merging nuclei, the emission lines exhibit broad and asymmetric profiles that suggest outflows powered either by a very young expanding radio jet or by AGN radiation. At ≳50 kpc from the system, we found a fainter extended-emission region that may be a part of a radio-jet-driven outflow.

  11. Actively Star Forming Elliptical Galaxies at Low Redshifts in the Sloan Digital Sky Survey

    CERN Document Server

    Fukugita, M; Turner, E L; Helmboldt, J; Nichol, R C; Fukugita, Masataka; Nakamura, Osamu; Turner, Edwin L.; Helmboldt, Joe

    2004-01-01

    We report discovery of actively star forming elliptical galaxies in a morphologically classified sample of bright galaxies at a low redshift obtained from the Sloan Digital Sky Survey. The emission lines of these galaxies do not show the characteristics of active galactic nuclei, and thus their strong H$\\alpha$ emission is ascribed to star formation with a rate nearly as high as that is seen in typical late spiral galaxies. This is taken as evidence against the traditional view that all elliptical galaxies formed early and now evolve only passively. The frequency of such star forming elliptical galaxies is a few tenths of a percent in the sample, but increases to 3% if we include active S0 galaxies. We may identify these galaxies as probable progenitors of so-called E+A galaxies that show the strong Balmer absorption feature of A stars superimposed on an old star population. The approximate match of the abundance of active elliptical plus S0 galaxies with that of E+A galaxies indicates that the duration of su...

  12. The Baryon Cycle at High Redshifts: Effects of Galactic Winds on Galaxy Evolution in Overdense and Average Regions

    CERN Document Server

    Sadoun, Raphael; Choi, Jun-Hwan; Romano-Díaz, Emilio

    2015-01-01

    We use high-resolution cosmological zoom-in simulations in order to analyze galaxy evolution at redshifts z~6-12 in highly-overdense 5 sigma density peaks. Strong stellar feedback, in the form of galactic winds, is expected to play an important role in the evolution of these regions. We investigate the effects of these winds by comparing different galactic outflow prescriptions, including (i) a constant velocity model (CW), (ii) a variable velocity model scaling with galaxy properties (VW), and (iii) a model with no outflows (NW). The CW model is also applied to a simulation of an average density region to study the impact of environment on galaxy evolution. A direct consequence of the overdensity is a shallow galaxy mass function slope at the low-mass end and an accelerated evolution of dark matter and baryonic structures. The overdensity hosts massive haloes, up to ~10^{12} Msun, with embedded galaxies up to ~10^{11} Msun in stellar mass by z~6, which are absent in the "normal" region. The CW model leads to...

  13. Discovery of intermediate redshift galaxy clusters in the ROSAT NEP field. [North Ecliptic Pole

    Science.gov (United States)

    Burg, R.; Giacconi, R.; Huchra, J.; Mackenty, J.; Mclean, B.; Geller, M.; Hasinger, G.; Marzke, R.; Schmidt, M.; Truemper, J.

    1992-01-01

    We report preliminary results from a program to identify optical counterparts of ROSAT sources in the North Ecliptic Pole (NEP) region. The most striking X-ray feature reported by Hasinger et al. (1991) is an extended low surface brightness region of X-ray emission. Within the two X-ray contours of highest count rate we find a cluster of galaxies at a redshift of 0.09 and an early-type galaxy at a redshift of 0.03. X-ray emission from these objects may provide an explanation for the observed X-ray morphology. We also find evidence that other X-ray sources in this region are coincident with clusters or groups of galaxies at redshifts between 0.08 and 0.09. The presence of at least five X-ray detected clusters or groups in this narrow redshift band within a 1.5 deg radius field seems to indicate the existence of a moderate redshift supercluster. The existence of these clusters will have major implications for the study of large-scale structure through X-ray surveys such as ROSAT.

  14. The Host Galaxies of Fast-Ejecta Core-Collapse Supernovae

    Science.gov (United States)

    Kelly, Patrick L.; Filippenko, Alexei V.; Modjaz, Maryam; Kocevski, Daniel

    2014-01-01

    Spectra of broad-lined Type Ic supernovae (SN Ic-BL), the only kind of SN observed at the locations of long-duration gamma-ray bursts (LGRBs), exhibit wide features indicative of high ejecta velocities ((is) approximately 0.1c). We study the host galaxies of a sample of 245 low-redshift (z (is) less than 0.2) core-collapse SN, including 17 SN Ic-BL, discovered by galaxy-untargeted searches, and 15 optically luminous and dust-obscured z (is) less than 1.2 LGRBs. We show that, in comparison with SDSS galaxies having similar stellar masses, the hosts of low-redshift SN Ic- BL and z (is) is less than 1.2 LGRBs have high stellar-mass and star-formation-rate densities. Core-collapse SN having typical ejecta velocities, in contrast, show no preference for such galaxies. Moreover, we find that the hosts of SN Ic-BL, unlike those of SN Ib/Ic and SN II, exhibit high gas velocity dispersions for their stellar masses. The patterns likely reflect variations among star-forming environments, and suggest that LGRBs can be used as probes of conditions in high-redshift galaxies. They may be caused by efficient formation of massive binary progenitors systems in densely star-forming regions, or, less probably, a higher fraction of stars created with the initial masses required for a SN Ic-BL or LGRB. Finally, we show that the preference of SN Ic-BL and LGRBs for galaxies with high stellar-mass and star-formation-rate densities cannot be attributed to a preference for low metal abundances but must reflect the influence of a separate environmental factor.

  15. Near-infrared imaging of the host galaxies of three radio-loud quasars at z = 1.5

    CERN Document Server

    Falomo, R; Treves, A; Falomo, Renato; Kotilainen, Jari; Treves, Aldo

    2000-01-01

    We present high spatial resolution near-infrared H-band (1.65 microns) images, taken with ISAAC on UT1 of ESO VLT, of three radio-loud quasars at z = 1.5, as a pilot study for imaging of a larger sample of radio-loud and radio-quiet quasars in the redshift range 1 < z < 2. We are able to clearly detect the host galaxy in two quasars (PKS 0000-177 and PKS 0348-120) and marginally in the third (PKS 0402-362). The host galaxies appear compact (average bulge scale-length R(e) = 4 kpc) and luminous (average M(H) = -27.6+-0.1). They are 2.5 mag more luminous than the typical galaxy luminosity (M*(H) = -25.0+-0.2), and are comparable to the hosts of low redshift radio-loud quasars (M(H) = -26), taking into account passive stellar evolution. Their luminosities are also similar to those of high redshift radio galaxies. All three quasars have at least one close companion galaxy at a projected distance < 50 kpc from the quasar, assuming they are at the same redshift.

  16. Improving Type Ia Supernova Standard Candle Cosmology Measurements Using Observations of Early-Type Host Galaxies

    Science.gov (United States)

    Meyers, Joshua Evan

    Type Ia supernovae (SNe Ia) are the current standard-bearers for dark energy but face several hurdles for their continued success in future large surveys. For example, spectroscopic classification of the myriad SNe soon to be discovered will not be possible, and systematics from uncertainties in dust corrections and the evolution of SN demographics and/or empirical calibrations used to standardize SNe Ia must be studied. Through the identification of low-dust host galaxies and through increased understanding of both the SN - progenitor connections and empirical calibrations, host galaxy information may offer opportunities to improve the cosmological utility of SNe Ia. The first half of this thesis analyzes the sample of SNe Ia discovered by the Hubble Space Telescope (HST) Cluster Supernova Survey augmented with HST-observed SNe Ia in the Great Observatories Origins Deep Survey (GOODS) fields. Correlations between properties of SNe and their host galaxies are examined at high redshift. Using galaxy color and quantitative morphology to determine the red sequence in 25 clusters, a model is developed to distinguish passively evolving early-type galaxies from star-forming galaxies in both clusters and the field. With this approach, 6 early-type cluster member hosts and 11 SN Ia early-type field hosts are identified. For the first time at z > 0.9, the correlation between host galaxy type and the rise and fall time of SN Ia light curves is confirmed. The relatively simple spectral energy distributions of early-type galaxies also enables stellar mass measurements for these hosts. In combination with literature host mass measurements, these measurements are used to show, at z > 0.9, a hint of the correlation between host mass and Hubble residuals reported at lower redshift. By simultaneously fitting cluster galaxy formation histories and dust content to the scatter of the cluster red sequences, it is shown that dust reddening of early-type cluster SN hosts is likely less

  17. The age of extremely red and massive galaxies at very high redshift

    CERN Document Server

    Castro-Rodriguez, N

    2011-01-01

    Aims. We present a determination of the intrinsic colors and ages of galaxies at very high redshift, in particular old galaxies (OGs) within extremely red objects (EROs). To date, the definition of EROs has been restricted to objects with z2.5). We therefore, refer to these objects as very high-redshift EROs (Z-EROS, herein). Methods. We analyze 63,550 galaxies selected in the XMM-LSS field. To obtain a reasonably sized sample of EROs, it is essential to consider a very wide area surveys. We identify targets within an area of 0.77 square degrees for which optical to mid-infrared data are available from SUBARU, UKIDSS, and Spitzer. We select Z-EROs based on their colors, and then perform a selection of only OGs. One of our novel innovations is to adapt the traditional method of EROs selection based on the filters I and K, to higher redshifts. Using our method, we identify 20 objects that satisfy the conditions required to be Z-EROs/OGs at redshifts 2.5~4.7. After including additional galaxies with z<2.5 ana...

  18. Confronting predictions of the galaxy stellar mass function with observations at high-redshift

    CERN Document Server

    Wilkins, Stephen M; Croft, Rupert; Khandai, Nishikanta; Feng, Yu; Bunker, Andrew; Coulton, William

    2013-01-01

    We investigate the evolution of the galaxy stellar mass function at high-redshift ($z\\ge 5$) using a pair of large cosmological hydrodynamical simulations: {\\em MassiveBlack} and {\\em MassiveBlack-II}. By combining these simulations we can study the properties of galaxies with stellar masses greater than $10^{8}\\,{\\rm M_{\\odot}}\\,h^{-1}$ and (co-moving) number densities of $\\log_{10}(\\phi\\, [{\\rm Mpc^{-3}\\,dex^{-1}}\\,h^{3}])>-8$. Observational determinations of the galaxy stellar mass function at very-high redshift typically assume a relation between the observed UV luminosity and stellar mass-to-light ratio which is applied to high-redshift samples in order to estimate stellar masses. This relation can also be measured from the simulations. We do this, finding two significant differences with the usual observational assumption: it evolves strongly with redshift and has a different shape. Using this relation to make a consistent comparison between galaxy stellar mass functions we find that at $z=6$ and above ...

  19. Compact Groups of Galaxies with Complete Spectroscopic Redshifts in the Local Universe

    CERN Document Server

    Sohn, Jubee; Geller, Margaret J; Diaferio, Antonaldo; Rines, Kenneth J; Lee, Myung Gyoon; Lee, Gwang-Ho

    2016-01-01

    Dynamical analysis of compact groups provides important tests of models of compact group formation and evolution. By compiling 2066 redshifts from FLWO/FAST, from the literature, and from SDSS DR12 in the fields of compact groups in \\citet{McC09}, we construct the largest sample of compact groups with complete spectroscopic redshifts in the redshift range $0.01 < z < 0.22$. This large redshift sample shows that the interloper fraction in the \\citet{McC09} compact group candidates is $\\sim 42\\%$. A secure sample of 332 compact groups includes 192 groups with four or more member galaxies and 140 groups with three members. The fraction of early-type galaxies in these compact groups is 62\\%, slightly higher than for the original Hickson compact groups. The velocity dispersions of early- and late-type galaxies in compact groups change little with groupcentric radius; the radii sampled are less than $100 ~h^{-1}$ kpc, smaller than the radii typically sampled by members of massive clusters of galaxies. The phy...

  20. CLASH: Photometric redshifts with 16 HST bands in galaxy cluster fields

    CERN Document Server

    Jouvel, S; Lahav, O; Seitz, S; Molino, A; Coe, D; Postman, M; Moustakas, L; Benìtez, N; Rosati, P; Balestra, I; Grillo, C; Bradley, L; Fritz, A; Kelson, D; Koekemoer, A M; Lemze, D; Medezinski, E; Mercurio, A; Moustakas, J; Nonino, M; Scodeggio, M; Zheng, W; Zitrin, A; Bartelmann, M; Bouwens, R; Broadhurst, T; Donahue, M; Ford, H; Graves, G; Infante, L; Jimenez-Teja, Y; Lazkoz, R; Melchior, P; Meneghetti, M; Merten, J; Ogaz, S; Umetsu, K

    2013-01-01

    The Cluster Lensing And Supernovae survey with Hubble (CLASH) is an Hubble Space Telescope (HST) Multi-Cycle Treasury program observing 25 massive galaxy clusters. CLASH observations are carried out in 16 bands from UV to NIR to derive accurate and reliable estimates of photometric redshifts. We present the CLASH photometric redshifts and study the photometric redshift accuracy of the arcs in more detail for the case of MACS1206.2-0847. We use the publicly available Le Phare and BPZ photometric redshift codes on 17 CLASH galaxy clusters. Using Le Phare code for objects with StoN>=10, we reach a precision of 3%(1+z) for the strong lensing arcs, which is reduced to 2.4%(1+z) after removing outliers. For galaxies in the cluster field the corresponding values are 4%(1+z) and 3%(1+z). Using mock galaxy catalogues, we show that 3%(1+z) precision is what one would expect from the CLASH photometry when taking into account extinction from dust, emission lines and the finite range of SEDs included in the photo-z templa...

  1. THERMAL AND RADIATIVE ACTIVE GALACTIC NUCLEUS FEEDBACK HAVE A LIMITED IMPACT ON STAR FORMATION IN HIGH-REDSHIFT GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Roos, Orianne; Juneau, Stéphanie; Bournaud, Frédéric; Gabor, Jared M., E-mail: orianne.roos@cea.fr [CEA-Saclay, F-91190 Gif-sur-Yvette (France)

    2015-02-10

    The effects of active galactic nuclei (AGNs) on their host galaxies depend on the coupling between the injected energy and the interstellar medium (ISM). Here, we model and quantify the impact of long-range AGN ionizing radiation—in addition to the often considered small-scale energy deposition—on the physical state of the multi-phase ISM of the host galaxy and on its total star formation rate (SFR). We formulate an AGN spectral energy distribution matched with observations, which we use with the radiative transfer (RT) code Cloudy to compute AGN ionization in a simulated high-redshift disk galaxy. We use a high-resolution (∼6 pc) simulation including standard thermal AGN feedback and calculate RT in post-processing. Surprisingly, while these models produce significant AGN-driven outflows, we find that AGN ionizing radiation and heating reduce the SFR by a few percent at most for a quasar luminosity (L {sub bol} = 10{sup 46.5} erg s{sup –1}). Although the circumgalactic gaseous halo can be kept almost entirely ionized by the AGN, most star-forming clouds (n ≳ 10{sup 2} {sup –} {sup 3} cm{sup –3}) and even the reservoirs of cool atomic gas (n ∼ 0.3-10 cm{sup –3})—which are the sites of future star formation (SF; 100-200 Myr), are generally too dense to be significantly affected. Our analysis ignores any absorption from a putative torus, making our results upper limits on the effects of ionizing radiation. Therefore, while the AGN-driven outflows can remove substantial amounts of gas in the long term, the impact of AGN feedback on the SF efficiency in the interstellar gas in high-redshift galaxies is marginal, even when long-range radiative effects are accounted for.

  2. Dark Energy Survey Year 1 Results: Redshift distributions of the weak lensing source galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Hoyle, B.; et al.

    2017-08-04

    We describe the derivation and validation of redshift distribution estimates and their uncertainties for the galaxies used as weak lensing sources in the Dark Energy Survey (DES) Year 1 cosmological analyses. The Bayesian Photometric Redshift (BPZ) code is used to assign galaxies to four redshift bins between z=0.2 and 1.3, and to produce initial estimates of the lensing-weighted redshift distributions $n^i_{PZ}(z)$ for bin i. Accurate determination of cosmological parameters depends critically on knowledge of $n^i$ but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts $n^i(z)=n^i_{PZ}(z-\\Delta z^i)$ to correct the mean redshift of $n^i(z)$ for biases in $n^i_{\\rm PZ}$. The $\\Delta z^i$ are constrained by comparison of independently estimated 30-band photometric redshifts of galaxies in the COSMOS field to BPZ estimates made from the DES griz fluxes, for a sample matched in fluxes, pre-seeing size, and lensing weight to the DES weak-lensing sources. In companion papers, the $\\Delta z^i$ are further constrained by the angular clustering of the source galaxies around red galaxies with secure photometric redshifts at 0.15

  3. The afterglow and the host galaxy of GRB 011211

    CERN Document Server

    Jakobsson, P; Fynbo, J P U; Gorosabel, J; Pedersen, K; Burud, I; Levan, A J; Kouveliotou, C; Tanvir, N R; Fruchter, A S; Rhoads, J; Grav, T; Hansen, M W; Michelsen, R; Andersen, M I; Jensen, B L; Pedersen, H; Thomsen, B; Weidinger, M; Bhargavi, S G; Cowsik, R; Pandey, S B

    2003-01-01

    We present optical, near-infrared, and X-ray observations of the optical afterglow (OA) of the X-ray rich, long-duration gamma-ray burst GRB 011211. Hubble Space Telescope (HST) data obtained 14, 26, 32, and 59 days after the burst, show the host galaxy to have a morphology that is fairly typical of blue galaxies at high redshift. We measure its magnitude to be R = 24.95 +/- 0.11. We detect a break in the OA R-band light curve which is naturally accounted for by a collimated outflow geometry. By fitting a broken power-law to the data we find a best fit with a break 1.56 +/- 0.02 days after the burst, a pre-break slope of alpha_1 = -0.95 +/- 0.02, and a post-break slope of alpha_2 = -2.11 +/- 0.07. The UV-optical spectral energy distribution (SED) around 14 hours after the burst is best fit with a power-law with index beta = -0.56 +/- 0.19 reddened by an SMC-like extinction law with a modest A_V = 0.08 +/- 0.08 mag. By comparison, from the XMM-Newton X-ray data at around the same time, we find a decay index of...

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

    CERN Document Server

    Nayyeri, Hooshang; Hemmati, Shoubaneh; De Barros, Stephane; Ferguson, Henry; Wiklind, Tommy; Dahlen, Tomas; Dickinson, Mark; Giavalisco, Mauro; Fontana, Adriano; Ashby, Mathew; Barro, Guillermo; Guo, Yicheng; Hathi, Nimish; Kassin, Susan; Koekemoer, Anton; Willner, Steven

    2014-01-01

    We use data taken as part of HST/WFC3 observations of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) to identify massive and evolved galaxies at 3galaxies. Using 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 (SED) of the BBGs show that the candidate galaxies have average estimated ages of ~800 Myr and average stellar masses of ~5x10^10 M_sun, consistent with being old and massive systems. Two of our BBG cand...

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

    Science.gov (United States)

    Straka, Lorrie A.; MUSE GTO Consortium

    2017-03-01

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

  6. The Red Sequence of High-Redshift Clusters: a Comparison with Cosmological Galaxy Formation Models

    OpenAIRE

    Menci, N.; Rosati, P.; Gobat, R.; Strazzullo, V.; Rettura, A.; S. Mei; Demarco, R.

    2008-01-01

    We compare the results from a semi-analytic model of galaxy formation with spectro-photometric observations of distant galaxy clusters observed in the range 0.8< z< 1.3. We investigate the properties of their red sequence (RS) galaxies and compare them with those of the field at the same redshift. In our model we find that i) a well-defined, narrow RS is obtained already by z= 1.2; this is found to be more populated than the field RS, analogously to what observed and predicted at z=0; ii) the...

  7. IMPROVED MOCK GALAXY CATALOGS FOR THE DEEP2 GALAXY REDSHIFT SURVEY FROM SUBHALO ABUNDANCE AND ENVIRONMENT MATCHING

    Energy Technology Data Exchange (ETDEWEB)

    Gerke, Brian F.; Wechsler, Risa H.; Behroozi, Peter S. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, M/S 29, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California-Irvine, Irvine, CA 92697 (United States); Yan, Renbin [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Coil, Alison L., E-mail: bgerke@slac.stanford.edu [Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Dr., MC 0424, La Jolla, CA 92093 (United States)

    2013-09-15

    We develop empirical methods for modeling the galaxy population and populating cosmological N-body simulations with mock galaxies according to the observed properties of galaxies in survey data. We use these techniques to produce a new set of mock catalogs for the DEEP2 Galaxy Redshift Survey based on the output of the high-resolution Bolshoi simulation, as well as two other simulations with different cosmological parameters, all of which we release for public use. The mock-catalog creation technique uses subhalo abundance matching to assign galaxy luminosities to simulated dark-matter halos. It then adds color information to the resulting mock galaxies in a manner that depends on the local galaxy density, in order to reproduce the measured color-environment relation in the data. In the course of constructing the catalogs, we test various models for including scatter in the relation between halo mass and galaxy luminosity, within the abundance-matching framework. We find that there is no constant-scatter model that can simultaneously reproduce both the luminosity function and the autocorrelation function of DEEP2. This result has implications for galaxy-formation theory, and it restricts the range of contexts in which the mock catalogs can be usefully applied. Nevertheless, careful comparisons show that our new mock catalogs accurately reproduce a wide range of the other properties of the DEEP2 catalog, suggesting that they can be used to gain a detailed understanding of various selection effects in DEEP2.

  8. The DEEP2 Galaxy Redshift Survey: The Red Sequence AGN Fraction and its Environment and Redshift Dependence

    CERN Document Server

    Montero-Dorta, Antonio D; Yan, Renbin; Cooper, Michael C; Newman, Jeffery A; Georgakakis, Antonis; Prada, Francisco; Davis, Marc; Nandra, Kirpal; Coil, Alison

    2008-01-01

    We measure the dependence of the AGN fraction on local environment at z~1, using spectroscopic data taken from the DEEP2 Galaxy Redshift Survey, and Chandra X-ray data from the All-Wavelength Extended Groth Strip International Survey (AEGIS). To provide a clean sample of AGN we restrict our analysis to the red sequence population; this also reduces additional colour-environment correlations. We find evidence that high redshift LINERs in DEEP2 tend to favour higher density environments relative to the red population from which they are drawn. In contrast, Seyferts and X-ray selected AGN at z~1 show little (or no) environmental dependencies within the same underlying population. We compare these results with a sample of local AGN drawn from the SDSS. Contrary to the high redshift behaviour, we find that both LINERs and Seyferts in the SDSS show a slowly declining red sequence AGN fraction towards high density environments. Interestingly, at z~1 red sequence Seyferts and LINERs are approximately equally abundant...

  9. Dusty Star Forming Galaxies and Supermassive Black Holes at High Redshifts: In- Situ Coevolution

    Science.gov (United States)

    Mancuso, Claudia

    2016-10-01

    We have exploited the continuity equation approach and the star-formation timescales derived from the observed 'main sequence' relation (Star Formation Rate vs Stellar Mass), to show that the observed high abundance of galaxies with stellar masses ≥ a few 10^10 M⊙ at redshift z ≥ 4 implies the existence of a galaxy population featuring large star formation rates (SFRs) ψ ≥ 10^2 M⊙ yr^-1 in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z ≤ 3 in the Far-InfraRed (FIR) band by the Herschel space observatory. We work out specific predictions for the evolution of the corresponding stellar mass and SFR functions out to z ∼10, elucidating that the number density at z ≤ 8 for SFRs ψ ≥ 30 M⊙ yr^-1 cannot be estimated relying on the UltraViolet (UV) luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from AzTEC-LABOCA, SCUBA-2 and ALMA-SPT surveys are already digging into it. We substantiate how an observational strategy based on a color preselection in the far-IR or (sub-)mm band with Herschel and SCUBA-2, supplemented by photometric data via on-source observations with ALMA, can allow to reconstruct the bright end of the SFR functions out to z ≤ 8. In parallel, such a challenging task can be managed by exploiting current UV surveys in combination with (sub-)mm observations by ALMA and NIKA2. The same could be done with radio observations by SKA and its precursors. In particular we have worked out predictions for the radio counts of star-forming galaxies down to nJy levels, along with redshift distributions down to the detection limits of the phase 1 Square Kilometer Array MID telescope (SKA1-MID) and of its precursors. To do that we

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-05-01

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

  11. High redshift galaxies and the Lyman-alpha forest in a CDM universe

    CERN Document Server

    Croft, R A C; Springel, V; Westover, M; White, M; Croft, Rupert A.C.; Hernquist, Lars; Springel, Volker; Westover, Michael; White, Martin

    2002-01-01

    We use a cosmological hydrodynamic simulation of a cold dark matter universe to investigate theoretically the relationship between high redshift galaxies and the Lyman=alpha forest at redshift z=3. Galaxies in the simulation are surrounded by halos of hot gas, which nevertheless contain enough neutral hydrogen to cause a Ly-alpha flux decrement, its strength increasing with galaxy mass. A comparison with recent observational data by Adelberger et. al on the Ly-alpha forest around galaxies reveals that actual galaxies may have systematically less Ly-alpha absorption within 1 Mpc of them than our simulated galaxies. In order to investigate this possibility, we add several simple prescriptions for galaxy feedback on the IGM to the evolved simulation. These include the effect of photoionizing background radiation coming from galactic sources, galactic winds whose only effect is to deposit thermal energy into the IGM, and another, kinetic model for winds, which are assumed to evacuate cavities in the IGM around ga...

  12. The Quest for Dusty Star-forming Galaxies at High Redshift z>4

    CERN Document Server

    Mancuso, C; Shi, J; Gonzalez-Nuevo, J; Aversa, R; Danese, L

    2016-01-01

    We exploit the continuity equation approach and the `main sequence' star-formation timescales to show that the observed high abundance of galaxies with stellar masses > a few 10^10 M_sun at redshift z>4 implies the existence of a galaxy population featuring large star formation rates (SFRs) > 10^2 M_sun/yr in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z30 M_sun/yr cannot be estimated relying on the UV luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from AzTEC-LABOCA, SCUBA-2 and ALMA-SPT surveys are already digging into it. We substantiate how an observational strategy based on a color preselection in the far-IR or (sub-)mm band with Herschel and SCUBA-2, supplemented by photometric data...

  13. Herschel-ATLAS: The Angular Correlation Function of Submillimetre Galaxies at High and Low Redshift

    Science.gov (United States)

    Maddox, S. J.; Dunne, L.; Rigby, E.; Eales, S.; Cooray, A.; Scott, D.; Peacock, J. A.; Negrello, M.; Smith, D. J. B.; Benford, D.; Amblard, A.; Auld, R.; Baes, M.; Bonfield, D.; Burgarella, D.; Buttiglione, S.; Cava, A.; Clements, D.; Dariush, A.; deZotti, G.; Dye, S.; Frayer, D.; Fritz, J.; Gonzalez-Nuevo, J.; Herranz, D.

    2010-01-01

    We present measurements of the angular correlation function of galaxies selected from the first field of the H-ATLAS survey. Careful removal of the background from galactic cirrus is essential, and currently dominates the uncertainty in our measurements. For our 250 micrometer-selected sample we detect no significant clustering, consistent with the expectation that the 250 pm-selected sources are mostly normal galaxies at z < or equal to 1. For our 350 micrometer and 500 micrometer-selected samples we detect relatively strong clustering with correlation amplitudes A of 0.2 and 1.2 at 1', but with relatively large uncertainties. For samples which preferentially select high redshift galaxies at z approx. 2-3 we detect significant strong clustering, leading to an estimate of r(0) approx. 7-11/h Mpc. The slope of our clustering measurements is very steep. delta approx. 2. The measurements are consistent with the idea that sub-mm sources consist of a low redshift population of normal galaxies and a high redshift population of highly clustered star-bursting galaxies.

  14. Broadband and Narrowband Search for z < 1 Analogs of High Redshift Star Forming Galaxies

    Science.gov (United States)

    Rosenwasser, Benjamin; Barger, Amy J.; Wold, Isak; Lauchlan Cowie, Lennox

    2017-01-01

    Studies of high redshift (z > 6) galaxies rely on extreme broadband colors from Spitzer/IRAC to select samples of low-mass star forming galaxies. These broadband excess searches are biased towards galaxies with the strongest emission lines, and the extent to which existing studies miss fainter galaxies with lower star formation rates remains unknown. Using both broadband (BB) and narrowband (NB) imaging from the HyperSuprimeCam (HSC) and SuprimeCam (SC) on the Subaru Telescope, we have performed a search for z population. The search was performed over roughly 4 square degrees centered on the COSMOS field, and the narrowband filters allow us to probe fainter emission lines than the broadband searches. We carried out spectral followup of our BB excess and NB excess samples using WIYN/Hydra to measure redshifts and line ratios in order to understand the biases in the different selection techniques. We also investigate the rest frame UV properties of our sample using data from GALEX. This study demonstrates the effectiveness of using broadband colors to select intermediate redshift emission line galaxies.

  15. Building a Better Understanding of the High Redshift BOSS Galaxies as Tools for Cosmology

    CERN Document Server

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

    2015-01-01

    We explore the 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 catalogs. Specifically, we measure galaxy clustering in CMASS on small and intermediate scales ($r\\lesssim 50\\,h^{-1}$Mpc) by computing the two-point correlation function $-$ both projected and redshift-space $-$ of these galaxies, and a new statistic, $\\Sigma(\\pi)$, able to provide robust information about redshift-space distortions and large-scale bias. We interpret our clustering measurements by adopting a Halo Occupation Distribution (HOD) scheme that maps them onto high-resolution N-body cosmological simulations to produce suitable mock galaxy catalogs. The traditional HOD prescription can be applied to the r...

  16. Galaxy Redshifts from Discrete Optimization of Correlation Functions

    Science.gov (United States)

    Lee, Benjamin C. G.; Budavári, Tamás; Basu, Amitabh; Rahman, Mubdi

    2016-12-01

    We propose a new method of constraining the redshifts of individual extragalactic sources based on celestial coordinates and their ensemble statistics. Techniques from integer linear programming (ILP) are utilized to optimize simultaneously for the angular two-point cross- and autocorrelation functions. Our novel formalism introduced here not only transforms the otherwise hopelessly expensive, brute-force combinatorial search into a linear system with integer constraints but also is readily implementable in off-the-shelf solvers. We adopt Gurobi, a commercial optimization solver, and use Python to build the cost function dynamically. The preliminary results on simulated data show potential for future applications to sky surveys by complementing and enhancing photometric redshift estimators. Our approach is the first application of ILP to astronomical analysis.

  17. Galaxy Redshifts from Discrete Optimization of Correlation Functions

    CERN Document Server

    Lee, Benjamin C G; Basu, Amitabh

    2016-01-01

    We propose a new method of constraining the redshifts of individual extragalactic sources based on their celestial coordinates. Techniques from integer linear programming are utilized to optimize simultaneously for the angular two-point cross- and autocorrelation functions. Our novel formalism introduced here not only transforms the otherwise hopelessly expensive, brute-force combinatorial search into a linear system with integer constraints but is also readily implementable in off-the-shelf solvers. We adopt Gurobi and use Python to dynamically build the cost function. The preliminary results on simulated data show great promise for future applications to sky surveys by complementing and enhancing photometric redshift estimators. Our approach is the first use of linear programming in astronomy.

  18. AGN-host connection at 0.5 < z < 2.5: A rapid evolution of AGN fraction in red galaxies during the last 10 Gyr

    Science.gov (United States)

    Wang, Tao; Elbaz, D.; Alexander, D. M.; Xue, Y. Q.; Gabor, J. M.; Juneau, S.; Schreiber, C.; Zheng, X.-Z.; Wuyts, S.; Shi, Y.; Daddi, E.; Shu, X.-W.; Fang, G.-W.; Huang, J.-S.; Luo, B.; Gu, Q.-S.

    2017-05-01

    We explore the dependence of the incidence of moderate-luminosity (L0.5-8 keV = 1041.9-43.7 erg s-1) active galactic nuclei (AGNs) and the distribution of their accretion rates on host color at 0.5 1010 M⊙. We use extinction-corrected rest-frame U-V colors to divide both AGN hosts and non-AGN galaxies into red sequence (red), green valley (green), and blue cloud (blue) populations. We find that the fraction of galaxies hosting an AGN at fixed X-ray luminosity increases with stellar mass and redshift for all the three galaxy populations, independent of their colors. However, both the AGN fraction at fixed stellar mass and its evolution with redshift are clearly dependent on host colors. Most notably, red galaxies have the lowest AGN fraction ( 5%) at z 1 yet with most rapid evolution with redshift, increasing by a factor of 5 (24%) at z 2. Green galaxies exhibit the highest AGN fraction across all redshifts, which is most pronounced at z 2 with more than half of them hosting an AGN at M∗ > 1010.6 M⊙. Together with the high AGN fraction in red galaxies at z 2, this indicates that (X-ray) AGNs could be important in both transforming (quenching) star-forming galaxies into quiescent ones and subsequently maintaining their quiescence at high redshift. Furthermore, consistent with previous studies at lower redshifts, we show that the probability of hosting an AGN for the total galaxy population can be characterized by a universal Eddington ratio (as approximated by LX/M∗) distribution (p(λEdd) λEdd-0.4), which is independent on host mass. Yet consistent with their different AGN fractions, galaxies with different colors appear to also have different p(λEdd) with red galaxies exhibiting more rapid redshift evolution compared with that for green and blue galaxies. Evidence for a steeper power-law distribution of p(λEdd) in red galaxies (p(λEdd) λEdd-0.6) is also presented, though larger samples are needed to confirm. These results suggest that the AGN accretion

  19. Galaxy evolution at low redshift?; 1, optical counts

    CERN Document Server

    Dennefeld, M

    1996-01-01

    We present bright galaxy number counts in the blue (16galaxies implying a ``high'' normalization of the local luminosity function. Our counts and colour distributions exhibit no large departure from what standard no-evolution models predict, removing the need for evolution of the galaxy population in the optical, out to Bj=21. This result disagrees with that of Maddox et al. (1990) on the APM catalog. We show that the APM and similar catalogs may be affected by a systematic magnitude scale error which would explain this discrepancy.

  20. Strong magnetic fields in normal galaxies at high redshifts

    CERN Document Server

    Bernet, Martin L; Lilly, Simon J; Kronberg, Philipp P; Dessauges-Zavadsky, Miroslava

    2008-01-01

    The origin and growth of magnetic fields in galaxies is still something of an enigma. It is generally assumed that seed fields are amplified over time through the dynamo effect, but there are few constraints on the timescale. It has recently been demonstrated that field strengths as traced by rotation measures of distant quasars are comparable to those seen today, but it was unclear whether the high fields were in the exotic environments of the quasars themselves or distributed along the line of sight. Here we demonstrate that the quasars with strong MgII absorption lines are unambiguously associated with larger rotation measures. Since MgII absorption occurs in the haloes of normal galaxies along the sightline to the quasars, this association requires that organized fields of surprisingly high strength are associated with normal galaxies when the Universe was only about one-third of its present age.

  1. Redshift Measurement and Spectral Classification for eBOSS Galaxies with the redmonster Software

    Science.gov (United States)

    Hutchinson, Timothy A.; Bolton, Adam S.; Dawson, Kyle S.; Allende Prieto, Carlos; Bailey, Stephen; Bautista, Julian E.; Brownstein, Joel R.; Conroy, Charlie; Guy, Julien; Myers, Adam D.; Newman, Jeffrey A.; Prakash, Abhishek; Carnero-Rosell, Aurelio; Seo, Hee-Jong; Tojeiro, Rita; Vivek, M.; Ben Zhu, Guangtun

    2016-12-01

    We describe the redmonster automated redshift measurement and spectral classification software designed for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). We describe the algorithms, the template standard and requirements, and the newly developed galaxy templates to be used on eBOSS spectra. We present results from testing on early data from eBOSS, where we have found a 90.5% automated redshift and spectral classification success rate for the luminous red galaxy sample (redshifts 0.6 ≲ z ≲ 1.0). The redmonster performance meets the eBOSS cosmology requirements for redshift classification and catastrophic failures and represents a significant improvement over the previous pipeline. We describe the empirical processes used to determine the optimum number of additive polynomial terms in our models and an acceptable {{Δ }}{χ }r2 threshold for declaring statistical confidence. Statistical errors on redshift measurement due to photon shot noise are assessed, and we find typical values of a few tens of km s-1. An investigation of redshift differences in repeat observations scaled by error estimates yields a distribution with a Gaussian mean and standard deviation of μ ˜ 0.01 and σ ˜ 0.65, respectively, suggesting the reported statistical redshift uncertainties are over-estimated by ˜54%. We assess the effects of object magnitude, signal-to-noise ratio, fiber number, and fiber head location on the pipeline’s redshift success rate. Finally, we describe directions of ongoing development.

  2. Galaxy Mergers and Dark Matter Halo Mergers in LCDM: Mass, Redshift, and Mass-Ratio Dependence

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Kyle R.; Bullock, James S.; Barton, Elizabeth J.; /UC, Irvine; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC

    2009-08-03

    We employ a high-resolution LCDM N-body simulation to present merger rate predictions for dark matter halos and investigate how common merger-related observables for galaxies - such as close pair counts, starburst counts, and the morphologically disturbed fraction - likely scale with luminosity, stellar mass, merger mass ratio, and redshift from z = 0 to z = 4. We provide a simple 'universal' fitting formula that describes our derived merger rates for dark matter halos a function of dark halo mass, merger mass ratio, and redshift, and go on to predict galaxy merger rates using number density-matching to associate halos with galaxies. For example, we find that the instantaneous merger rate of m/M > 0.3 mass ratio events into typical L {approx}> fL{sub *} galaxies follows the simple relation dN/dt {approx_equal} 0.03(1+f)Gyr{sup -1} (1+z){sup 2.1}. Despite the rapid increase in merger rate with redshift, only a small fraction of > 0.4L{sub *} high-redshift galaxies ({approx} 3% at z = 2) should have experienced a major merger (m/M > 0.3) in the very recent past (t < 100 Myr). This suggests that short-lived, merger-induced bursts of star formation should not contribute significantly to the global star formation rate at early times, in agreement with observational indications. In contrast, a fairly high fraction ({approx} 20%) of those z = 2 galaxies should have experienced a morphologically transformative merger within a virial dynamical time. We compare our results to observational merger rate estimates from both morphological indicators and pair-fraction based determinations between z = 0-2 and show that they are consistent with our predictions. However, we emphasize that great care must be made in these comparisons because the predicted observables depend very sensitively on galaxy luminosity, redshift, overall mass ratio, and uncertain relaxation timescales for merger remnants. We show that the majority of bright galaxies at z = 3 should have undergone a

  3. Redshift Weights for Baryon Acoustic Oscillations : Application to Mock Galaxy Catalogs

    CERN Document Server

    Zhu, Fangzhou; White, Martin; Ross, Ashley J; Zhao, Gongbo

    2016-01-01

    Large redshift surveys capable of measuring the Baryon Acoustic Oscillation (BAO) signal have proven to be an effective way of measuring the distance-redshift relation in cosmology. Building off the work in Zhu et al. (2015), we develop a technique to directly constrain the distance-redshift relation from BAO measurements without splitting the sample into redshift bins. We parametrize the distance-redshift relation, relative to a fiducial model, as a quadratic expansion. We measure its coefficients and reconstruct the distance-redshift relation from the expansion. We apply the redshift weighting technique in Zhu et al. (2015) to the clustering of galaxies from 1000 QuickPM (QPM) mock simulations after reconstruction and achieve a 0.75% measurement of the angular diameter distance $D_A$ at $z=0.64$ and the same precision for Hubble parameter H at $z=0.29$. These QPM mock catalogs are designed to mimic the clustering and noise level of the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 12 (DR12). W...

  4. The Hy-Redshift Universe: Galaxy Formation and Evolution at High Redshift

    Energy Technology Data Exchange (ETDEWEB)

    Bunker, A.J.; van Breugel, W.J.M.

    1999-11-03

    Hyron Spinrad's career has spanned several decades, and has stretched from our neighboring planets to the most remote galaxies in the Universe, pausing in between to ''enrich'' our knowledge of the compositions of stars.

  5. An HST/COS legacy survey of intervening SiIII absorption in the extended gaseous halos of low-redshift galaxies

    CERN Document Server

    Richter, P; Fechner, C; Herenz, P; Tepper-Garcia, T; Fox, A J

    2015-01-01

    Doubly ionized silicon (SiIII) is a powerful tracer of diffuse ionized gas inside and outside of galaxies. It can be observed in the local Universe in ultraviolet (UV) absorption against bright extragalactic background sources. We here present an extensive study of intervening SiIII- selected absorbers and their relation to the circumgalactic medium (CGM) of galaxies at low redshift (z12.2. We develop a geometrical model for the absorption-cross section of the CGM around the local galaxy population and find excellent agreement between the model predictions and the observations. We further compare redshifts and positions of the absorbers with that of ~64,000 galaxies using archival galaxy-survey data. For the majority of the absorbers we identify possible L>0.5L* host galaxies within 300 km/s of the absorbers and derive impact parameters rho<200 kpc, demonstrating that the spatial distributions of SiIII absorbers and galaxies are highly correlated. Our study indicates that the majority of SiIII-selected abs...

  6. Signatures of cool gas fueling a star-forming galaxy at redshift 2.3.

    Science.gov (United States)

    Bouché, N; Murphy, M T; Kacprzak, G G; Péroux, C; Contini, T; Martin, C L; Dessauges-Zavadsky, M

    2013-07-05

    Galaxies are thought to be fed by the continuous accretion of intergalactic gas, but direct observational evidence has been elusive. The accreted gas is expected to orbit about the galaxy's halo, delivering not just fuel for star formation but also angular momentum to the galaxy, leading to distinct kinematic signatures. We report observations showing these distinct signatures near a typical distant star-forming galaxy, where the gas is detected using a background quasar passing 26 kiloparsecs from the host. Our observations indicate that gas accretion plays a major role in galaxy growth because the estimated accretion rate is comparable to the star-formation rate.

  7. Supermassive Black Hole Binaries: Environment and Galaxy Host Properties of PTA and eLISA sources

    CERN Document Server

    Palafox, Eva Martínez; Colín, Pedro; Gottlöber, Stefan

    2014-01-01

    Supermassive black hole (BH) binaries would comprise the strongest sources of gravitational waves (GW) once they reach <<1 pc separations, for both pulsar timing arrays (PTAs) and space based (SB) detectors. While BH binaries coalescences constitute a natural outcome of the cosmological standard model and galaxy mergers, their dynamical evolution is still poorly understood and therefore their abundances at different stages. We use a dynamical model for the decay of BH binaries coupled with a cosmological simulation and semi-empirical approaches to the occupation of haloes by galaxies and BHs, in order to follow the evolution of the properties distribution of galaxies hosting BH binaries candidates to decay due to GWs emission. Our models allow us to relax simplifying hypothesis about the binaries occupation in galaxies and their mass, as well as redshift evolution. Following previously proposed electromagnetic (EM) signatures of binaries in the subpc regime, that include spectral features and variabilit...

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

    Science.gov (United States)

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

    2017-09-01

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

  9. Attenuation of TeV γ-rays by the starlight photon field of the host galaxy

    Science.gov (United States)

    Zacharias, Michael; Chen, Xuhui; Wagner, Stefan J.

    2017-03-01

    The absorption of TeV γ-ray photons produced in relativistic jets by surrounding soft photon fields is a long-standing problem of jet physics. In some cases, the most likely emission site close to the central black hole is ruled out because of the high opacity caused by strong optical and infrared photon sources, such as the broad-line region. Mostly neglected for jet modelling is the absorption of γ-rays in the starlight photon field of the host galaxy. Analysing the absorption for arbitrary locations and observation angles of the γ-ray emission site within the host galaxy, we find that the distance to the galaxy centre, the observation angle, and the distribution of starlight in the galaxy are crucial for the amount of absorption. We derive the absorption value for a sample of 20 TeV-detected blazars with a redshift zr host properties, such as starlight emissivity, galactic size, half-light radius, and redshift. While the uncertainty of the spectral properties of the extragalactic background light exceeds the effect of absorption by stellar light from the host galaxy in distant objects, the latter is a dominant effect in nearby sources. It may also be revealed in a differential comparison of sources with similar redshifts.

  10. UV spectroscopy of low-redshift active galaxies

    Science.gov (United States)

    Wu, C.-C.; Crenshaw, M.

    1993-01-01

    Ultraviolet spectra of bright Seyfert 1 galaxies will be obtained with the Hubble Space Telescope. Observations will be used to pursue the following goals: (1) Broad and narrow components of the strong emission lines will be deconvolved. (2) Broad-line profiles will be extracted for comparison with kinematic models; line ratios will be determined. (3) Many weak UV and emission lines from optical spectra will be compared for reddening along line of sight and chemical composition. (4) Absorption lines from Galactic halo, intergalactic medium and Seyfert galaxy will be used to establish physical conditions/chemical composition of the gas. (5) Strong emission Fe II in the UV will be used to determine FE II/L-alpha ratios for comparison with photoionization models. Other tasks relating to GTO 1170 program will be performed. It appears that NLR clouds in NGC 5548 experience much higher level of ionizing flux than those Seyfert 2 galaxies. Future observations will determine if this result extends to other Seyfert 1 galaxies.

  11. Galaxy formation in the PLANCK cosmology IV: the high-redshift universe

    CERN Document Server

    Clay, Scott; Wilkins, Stephen; Henriques, Bruno

    2015-01-01

    We present high-redshift predictions of the star-formation-rate distribution function (SFR DF), UV luminosity function (UV LF), galactic stellar mass function (GSMF), and specific star-formation rates (sSFRs) of galaxies from the latest version of the Munich semi-analytic model L-Galaxies. We find a good fit to both the shape and normalisation of the SFR DF at $z=4-7$, apart from a slight under-prediction at the low SFR end at $z=4$. Likewise, we find a good fit to the faint number counts for the observed UV LF; at brighter magnitudes our predictions lie below the observations, increasingly so at higher redshifts. At all redshifts and magnitudes, the raw (unattenuated) number counts for the UV LF lie above the observations. Because of the good agreement with the SFR we interpret our under-prediction as an over-estimate of the amount of dust in the model for the brightest galaxies, especially at high-redshift. While the shape of our GSMF matches that of the observations, we lie between (conflicting) observatio...

  12. A catalogue of photometric redshifts for the SDSS-DR9 galaxies

    CERN Document Server

    Brescia, M; Longo, G; De Stefano, V

    2014-01-01

    Accurate photometric redshifts for large samples of galaxies are among the main products of modern multiband digital surveys. Over the last decade, the Sloan Digital Sky Survey (SDSS) has become a sort of benchmark against which to test the various methods. We present an application of a new method to the estimation of photometric redshifts for the galaxies in the SDSS Data Release 9 (SDSS-DR9). Photometric redshifts for more than 143 million galaxies were produced and made available at the URL: http://dame.dsf.unina.it/catalog/DR9PHOTOZ/. The MLPQNA (Multi Layer Perceptron with Quasi Newton Algorithm) model provided within the framework of the DAMEWARE (DAta Mining and Exploration Web Application REsource) is an interpolative method derived from machine learning models. The obtained redshifts have an overall uncertainty of sigma=0.023 with a very small average bias of about 3x10^-5, and a fraction of catastrophic outliers of about 5%. This result is slightly better than what was already available in the lite...

  13. Derivation of chemical abundances in star-forming galaxies at intermediate redshift

    CERN Document Server

    Perez-Martinez, J M

    2014-01-01

    We have studied a sample of 11 blue, luminous, metal-poor galaxies at redshift 0.744 < z < 0.835 from the DEEP2 redshift survey. They were selected by the presence of the [OIII]4363 auroral line and the [OII]3726,3729 doublet together with the strong emission nebular [OIII] lines in their spectra from a sample of around 6000 galaxies within a narrow redshift range. All the spectra have been taken with DEIMOS, which is a multi-slit, double-beam spectrograph which uses slitmasks to allow the spectra from many objects to be imaged at the same time. The selected objects present high luminosities (20.3 < MB < 18.5), remarkable blue color index, and total oxygen abundances between 7.69 and 8.15 which represent 1/3 to 1/10 of the solar value. The wide spectral coverage (from 6500 to 9100 angstroms) of the DEIMOS spectrograph and its high spectral resolution, R around 5000, bring us an opportunity to study the behaviour of these star-forming galaxies at intermediate redshift with high quality spectra. We ...

  14. Redshift distributions of galaxies in the DES Science Verification shear catalogue and implications for weak lensing

    CERN Document Server

    Bonnett, C; Amara, A; Leistedt, B; Becker, M R; Bernstein, G M; Bridle, S; Bruderer, C; Busha, M T; Kind, M Carrasco; Childress, M J; Castander, F J; Chang, C; Crocce, M; Davis, T M; Eifler, T F; Frieman, J; Gangkofner, C; Gaztanaga, E; Glazebrook, K; Gruen, D; Kacprzak, T; King, A; Kwan, J; Lahav, O; Lewis, G; Lidman, C; Lin, H; MacCrann, N; Miquel, R; O'Neill, C R; Palmese, A; Peiris, H V; Refregier, A; Rozo, E; Rykoff, E S; Sadeh, I; Sánchez, C; Sheldon, E; Uddin, S; Wechsler, R H; Zuntz, J; Abbott, T; Abdalla, F B; Allam, S; Armstrong, R; Banerji, M; Bauer, A H; Benoit-Lévy, A; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Capozzi, D; Rosell, A Carnero; Carretero, J; Cunha, C E; D'Andrea, C B; da Costa, L N; DePoy, D L; Desai, S; Diehl, H T; Dietrich, J P; Doel, P; Neto, A Fausti; Fernandez, E; Flaugher, B; Fosalba, P; Gerdes, D W; Gruendl, R A; Honscheid, K; Jain, B; James, D J; Jarvis, M; Kim, A G; Kuehn, K; Kuropatkin, N; Li, T S; Lima, M; Maia, M A G; March, M; Marshall, J L; Martini, P; Melchior, P; Miller, C J; Neilsen, E; Nichol, R C; Nord, B; Ogando, R; Plazas, A A; Reil, K; Romer, A K; Roodman, A; Sako, M; Sanchez, E; Santiago, B; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Thomas, D; Vikram, V; Walker, A R

    2015-01-01

    We present photometric redshift estimates for galaxies used in the weak lensing analysis of the Dark Energy Survey Science Verification (DES SV) data. Four model- or machine learning-based photometric redshift methods -- ANNZ2, BPZ calibrated against BCC-Ufig simulations, SkyNet, and TPZ -- are analysed. For training, calibration, and testing of these methods, we construct a catalogue of spectroscopically confirmed galaxies matched against DES SV data. The performance of the methods is evaluated against the matched spectroscopic catalogue, focusing on metrics relevant for weak lensing analyses, with additional validation against COSMOS photo-zs. From the galaxies in the DES SV shear catalogue, which have mean redshift $0.72\\pm0.01$ over the range $0.3redshift distributi...

  15. Empirical solutions to the high-redshift overproduction of stars in modeled dwarf galaxies

    CERN Document Server

    White, Catherine E; Ferguson, Henry C

    2014-01-01

    Both numerical hydrodynamic and semi-analytic cosmological models of galaxy formation struggle to match observed star formation histories of galaxies in low-mass halos (M$_{\\rm{H}} \\lesssim 10^{11}$ \\msun), predicting more star formation at high redshift and less star formation at low redshift than observed. The fundamental problem is that galaxies' gas accretion and star formation rates are too closely coupled in the models: the accretion rate largely drives the star formation rate. Observations point to gas accretion rates that outpace star formation at high redshift, resulting in a buildup of gas and a delay in star formation until lower redshifts. We present three empirical adjustments of standard recipes in a semi-analytic model motivated by three physical scenarios that could cause this decoupling: 1) the mass loading factors of outflows driven by stellar feedback may have a steeper dependence on halo mass at earlier times, 2) the efficiency of star formation may be lower in low mass halos at high redsh...

  16. How robust are the size measurements of high-redshift compact galaxies?

    Energy Technology Data Exchange (ETDEWEB)

    Davari, Roozbeh [University of California, Riverside 900 University Avenue, Riverside, CA 92521 (United States); Ho, Luis C. [The Observatories of the Carnegie Institution for Science 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Peng, Chien Y. [Giant Magellan Telescope Organization 251 South Lake Avenue, Suite 300 Pasadena, CA 91101 (United States); Huang, Song [School of Space Science and Astronomy, Nanjing University, Nanjing 210093 (China)

    2014-05-20

    Massive quiescent galaxies at z ≈ 2 are apparently much more compact than galaxies of comparable mass today. How robust are these size measurements? We perform comprehensive simulations to determine possible biases and uncertainties in fitting single-component light distributions to real galaxies. In particular, we examine the robustness of the measurements of the luminosity, size, and other structural parameters. We devise simulations with increasing realism to systematically disentangle effects due to the technique (specifically using GALFIT) and the intrinsic structures of the galaxies. 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. In fact, we find that fitting multi-component galaxies with a single Sérsic profile, the procedure most commonly adopted in the literature, biases the inferred sizes higher by up to 10%-20%, which accentuates the amount of size evolution required. If the sky estimation has been done robustly and the model for the point-spread function is fairly accurate, GALFIT can retrieve the properties of single-component galaxies over a wide range of signal-to-noise ratios without introducing any systematic errors.

  17. Properties of a Gamma Ray Burst Host Galaxy at z ~ 5

    CERN Document Server

    Price, P A; Cowie, L L; Burnell, J Bell; Berger, E; Cucchiara, A; Fox, D B; Hook, I; Kulkarni, S R; Penprase, B; Roth, K C; Schmidt, B

    2007-01-01

    We describe the properties of the host galaxy of the gamma-ray burst GRB060510B based on a spectrum of the burst afterglow obtained with the Gemini North 8m telescope. The galaxy lies at a redshift of z = 4.941 making it the fourth highest spectroscopically identified burst host. However, it is the second highest redshift galaxy for which the quality of the spectrum permits a detailed metallicity analysis. The neutral hydrogen column density has a logarithmic value of 21.0--21.2 cm^-2 and the weak metal lines of Ni, S and Fe show that the metallicity is in excess of a tenth of solar which is far above the metallicities in damped Lyman alpha absorbers at high redshift. The tightest constraint is from the Fe lines which place [Fe/H] in excess of -0.8. We argue that the results suggest that metallicity bias could be a serious problem with inferring star formation from the GRB population and consider how future higher quality measurements could be used to resolve this question.

  18. Probing Dark Energy with Baryonic Acoustic Oscillations from Future Large Galaxy Redshift Surveys

    CERN Document Server

    Eisenstein, D J

    2003-01-01

    We show that the measurement of the baryonic acoustic oscillations in large high redshift galaxy surveys offers a precision route to the measurement of dark energy. The cosmic microwave background provides the scale of the oscillations as a standard ruler that can be measured in the clustering of galaxies, thereby yielding the Hubble parameter and angular diameter distance as a function of redshift. This, in turn, enables one to probe dark energy. We use a Fisher matrix formalism to study the statistical errors for redshift surveys up to z=3 and report errors on cosmography while marginalizing over a large number of cosmological parameters including a time-dependent equation of state. With redshifts surveys combined with cosmic microwave background satellite data, we achieve errors of 0.037 on Omega_x, 0.10 on w(z=0.8), and 0.28 on dw(z)/dz for cosmological constant model. Models with less negative w(z) permit tighter constraints. We test and discuss the dependence of performance on redshift, survey condition...

  19. The Evolutionary History of Lyman Break Galaxies Between Redshift 4 and 6: Observing Successive Generations of Massive Galaxies in Formation

    CERN Document Server

    Stark, Daniel P; Bunker, Andrew; Bundy, Kevin; Targett, Tom; Benson, Andrew; Lacy, Mark

    2009-01-01

    We present new measurements of the evolution in the Lyman break galaxy (LBG) population between z~4 and z~6. By utilizing the extensive multiwavelength datasets available in the GOODS fields, we identify 2443 B, 506 V, and 137 i'-band dropout galaxies likely to be at z~4, 5, and 6. With the goal of understanding the duration of typical star formation episodes in galaxies at z>4, we examine the distribution of stellar masses and ages as a function of cosmic time. We find that at a fixed rest-UV luminosity, the average stellar masses and ages of galaxies do not increase significantly between z~6 and 4. In order to maintain this near equilibrium in the average properties of high redshift LBGs, we argue that there must be a steady flux of young, newly-luminous objects at each successive redshift. When considered along with the short duty cycles inferred from clustering measurements, these results may suggest that galaxies are undergoing star formation episodes lasting only several hundred million years. In contra...

  20. The WiggleZ Dark Energy Survey: Cosmological neutrino mass constraint from blue high-redshift galaxies

    CERN Document Server

    Riemer--Sørensen, Signe; Parkinson, David; Davis, Tamara M; Brough, Sarah; Colless, Matthew; Contreras, Carlos; Couch, Warrick; Croom, Scott; Croton, Darren; Drinkwater, Michael J; Forster, Karl; Gilbank, David; Gladders, Mike; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, I-hui; Madore, Barry; Martin, D Christopher; Pimbblet, Kevin; Poole, Gregory B; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted K; Yee, H K C

    2011-01-01

    The absolute neutrino mass scale is currently unknown, but can be constrained from cosmology. The WiggleZ high redshift star-forming blue galaxy sample is less sensitive to systematics from non-linear structure formation, redshift-space distortions and galaxy bias than previous surveys. We obtain a upper limit on the sum of neutrino masses of 0.60eV (95% confidence) for WiggleZ+Wilkinson Microwave Anisotropy Probe. Combining with priors on the Hubble Parameter and the baryon acoustic oscillation scale gives an upper limit of 0.29eV, which is the strongest neutrino mass constraint derived from spectroscopic galaxy redshift surveys.

  1. Molecular gas properties of UV-luminous star-forming galaxies at low redshift

    CERN Document Server

    Gonçalves, T S; Overzier, R A; Pérez, L; Martin, D C

    2014-01-01

    Lyman break analogues (LBAs) are a population of star-forming galaxies at low redshift (z ~ 0.2) selected in the ultraviolet (UV). These objects present higher star formation rates and lower dust extinction than other galaxies with similar masses and luminosities in the local universe. In this work we present results from a survey with the Combined Array for Research in Millimetre-wave Astronomy (CARMA) to detect CO(1-0) emission in LBAs, in order to analyse the properties of the molecular gas in these galaxies. Our results show that LBAs follow the same Schmidt-Kennicutt law as local galaxies. On the other hand, they have higher gas fractions (up to 66%) and faster gas depletion time-scales (below 1 Gyr). These characteristics render these objects more akin to high-redshift star-forming galaxies. We conclude that LBAs are a great nearby laboratory for studying the cold interstellar medium in low-metallicity, UV-luminous compact star-forming galaxies.

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

    CERN Document Server

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

    2002-01-01

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

  3. Low-Metallicity Star Formation in High-Redshift Galaxies at z~8

    CERN Document Server

    Taniguchi, Y; Trump, J R

    2010-01-01

    Based on the recent very deep near-infrared imaging of the Hubble Ultra Deep Field with WFC3 on the Hubble Space Telescope, five groups published most probable samples of galaxies at z~8, selected by the so-called dropout method or photometric redshift; e.g., Y_105-dropouts (Y_105-J_125 > 0.8). These studies are highly useful for investigating both the early star formation history of galaxies and the sources of cosmic re-ionization. In order to better understand these issues, we carefully examine if there are low-$z$ interlopers in the samples of z~8 galaxy candidates. We focus on the strong emission-line galaxies at z~2 in this paper. Such galaxies may be selected as Y_105-dropouts since the [OIII] lambda 5007 emission line is redshifted into the J_125-band. We have found that the contamination from such low-$z$ interlopers is negligibly small. Therefore, all objects found by the five groups are free from this type of contamination. However, it remains difficult to extract real z~8 galaxies because all the s...

  4. New Image Statistics for Detecting Disturbed Galaxy Morphologies at High Redshift

    CERN Document Server

    Freeman, P E; Lee, A B; Newman, J A; Conselice, C J; Koekemoer, A M; Lotz, J M; Mozena, M

    2013-01-01

    Testing theories of hierarchical structure formation requires estimating the distribution of galaxy morphologies and its change with redshift. One aspect of this investigation involves identifying galaxies with disturbed morphologies (e.g., merging galaxies). This is often done by summarizing galaxy images using, e.g., the CAS and Gini-M20 statistics of Conselice (2003) and Lotz et al. (2004), respectively, and associating particular statistic values with disturbance. We introduce three statistics that enhance detection of disturbed morphologies at high-redshift (z ~ 2): the multi-mode (M), intensity (I), and deviation (D) statistics. We show their effectiveness by training a machine-learning classifier, random forest, using 1,639 galaxies observed in the H band by the Hubble Space Telescope WFC3, galaxies that had been previously classified by eye by the CANDELS collaboration (Grogin et al. 2011, Koekemoer et al. 2011). We find that the MID statistics (and the A statistic of Conselice 2003) are the most usef...

  5. A New Diagnostic Diagram of Ionization Source for High Redshift Emission Line Galaxies

    CERN Document Server

    Zhang, Kai

    2016-01-01

    We propose a new diagram, the Kinematic-Excitation diagram (KEx diagram), which uses the [OIII]/H\\beta\\ line ratio and the [OIII]5007 emission line width (\\sigma_{[OIII]}) to diagnose the ionization source and physical properties of the Active Galactic Nuclei (AGNs) and the star-forming galaxies (SFGs). The KEx diagram is a suitable tool to classify emission-line galaxies (ELGs) at intermediate redshift because it uses only the [OIII]5007 and H\\beta\\ emission lines. We use the SDSS DR7 main galaxy sample and the Baldwin-Phillips-Terlevich (BPT) diagnostic to calibrate the diagram at low redshift. We find that the diagram can be divided into 3 regions: one occupied mainly by the pure AGNs (KEx-AGN region), one dominated by composite galaxies (KEx-composite region), and one contains mostly SFGs (KEx-SFG region). AGNs are separated from SFGs in this diagram mainly because they preferentially reside in luminous and massive galaxies and have high [OIII]/H\\beta. The separation of AGN from star-forming galaxies is e...

  6. Intermittent Self-Sustaining Star Formation in Low-Redshift Galaxies Exhibiting a Peak Metallicity Plateau

    CERN Document Server

    Harwit, Martin

    2015-01-01

    The decline of star formation in massive low-redshift galaxies, often referred to as quenching, has been attributed to a variety of factors. Some proposals suggest that erupting active galactic nuclei may strip galaxies of their interstellar medium, and thus the ability to form stars. Here, we note that, whereas star formation is universal in small, low-redshift galaxies, fractional duty cycles of star formation steadily decline in galaxies of increasing mass, although star formation may not cease entirely. We show that, when infall of gas from extragalactic space ceases, galaxies of high stellar mass appear to sustain star formation on gas liberated in mass loss from evolved low- and intermediate-mass stars admixed with occasional Type II supernova ejecta. This model quantitatively accounts for the universal limiting metallicity plateau at a ratio of oxygen to hydrogen atoms, Z(O) = n(O)/n(H) = 0.0013, characterizing high-mass intermittently star-forming galaxies. We show that, when fractional duty cycles ar...

  7. NIHAO XIII: Clumpy discs or clumpy light in high-redshift galaxies?

    Science.gov (United States)

    Buck, Tobias; Macciò, Andrea V.; Obreja, Aura; Dutton, Aaron A.; Domínguez-Tenreiro, Rosa; Granato, Gian Luigi

    2017-07-01

    Many massive star-forming disc galaxies in the redshift range 3-0.5 are observed to have a clumpy morphology showing giant clumps of size ˜1 kpc and masses of about 107-1010 M⊙. The nature and fate of these giant clumps are still under debate. In this work, we use 19 high-resolution simulations of disc galaxies from the Numerical Investigations of Hundred Astrophysical Objects (NIHAO) sample to study the formation and evolution of clumps in the discs of high-redshift galaxies. We use mock Hubble Space Telescope-CANDELS observations created with the radiative transfer code grasil-3d to carry out, for the first time, a quantitative comparison of the observed fraction of clumpy galaxies and its evolution with redshift with simulations. We find a good agreement between the observed clumpy fraction and the one of the NIHAO galaxies. We find that dust attenuation can suppress intrinsically bright clumps and enhance less luminous ones. In our galaxy sample, we find clumps only in light (U band) from young stars but not in stellar mass surface density maps. This means that the NIHAO sample does not show clumpy stellar discs but rather a clumpy light distribution originating from clumpy star formation events. The clumps found in the NIHAO sample match observed age/colour gradients as a function of distance from the galaxy centre, but they show no sign of inward migration. Clumps in our simulations disperse on time-scales of about a hundred Myr and their contribution to bulge growth is negligible.

  8. Stellar Populations, Outflows, and Morphologies of High-Redshift Galaxies

    Science.gov (United States)

    Kornei, Katherine Anne

    Understanding the regulation and environment of star formation across cosmic time is critical to tracing the build-up of mass in the Universe and the interplay between the stars and gas that are the constituents of galaxies. Three studies are presented in this thesis, each examining a different aspect of star formation at a specific epoch. The first study presents the results of a photometric and spectroscopic survey of 321 Lyman break galaxies (LBGs) at z ˜ 3 to investigate systematically the relationship between Lyalpha emission and stellar populations. Lyalpha equivalent widths were calculated from rest-frame UV spectroscopy and optical/near-infrared/Spitzer photometry was used in population synthesis modeling to derive the key properties of age, dust extinction, star formation rate (SFR), and stellar mass. Using a variety of statistical tests, we find that Lyalpha equivalent width and age, SFR, and dust extinction, respectively, are significantly correlated in the sense that objects with strong Lyalpha emission also tend to be older, lower in star formation rate, and less dusty than objects with weak Lyalpha emission, or the line in absorption. We accordingly conclude that, within the LBG sample, objects with strong Lyalpha emission represent a later stage of galaxy evolution in which supernovae-induced outflows have reduced the dust covering fraction. The second study focuses specifically on galactic-scale outflowing winds in 72 star-forming galaxies at z ˜ 1 in the Extended Groth Strip. Galaxies were selected from the DEEP2 survey and follow-up LRIS spectroscopy was obtained covering SiII, CIV, FeII, MgII, and MgI lines in the rest-frame ultraviolet. Using GALEX, HST, and Spitzer imaging available for the Extended Groth Strip, we examine galaxies on a per-object basis in order to better understand both the prevalence of galactic outflows at z ˜ 1 and the star-forming and structural properties of objects experiencing outflows. Gas velocities, measured from

  9. Deep VLT spectroscopy of high redshift radio galaxy MRC 2104-242 Evidence for a metallicity gradient

    CERN Document Server

    Overzier, R; Kurk, J D; De Breuck, C

    2001-01-01

    In this contribution we will present deep VLT spectroscopy observations of the giant emission line halo around the z=2.49 radio galaxy MRC 2104-242. The morphology of the halo is dominated by two spatially resolved regions. Lya is extended by >12" along the radio axis, C IV and He II are extended by ~8". The overall spectrum is typical for that of high redshift radio galaxies. Interestingly, N V is present in the spectrum of the region associated with the center of the galaxy hosting the radio source, the northern region, while absent in the southern region. Using a simple photoionization model, the difference in N V can be explained due to a metallicity gradient within the halo. This is consistent with a scenario in which the halo is formed by a massive cooling flow or originates from the debris of the merging of two or more galaxies. However, also other mechanisms such as jet-cloud interactions or starburst-winds could be important.

  10. Radio Galaxy Zoo: host galaxies and radio morphologies derived from visual inspection

    Science.gov (United States)

    Banfield, J. K.; Wong, O. I.; Willett, K. W.; Norris, R. P.; Rudnick, L.; Shabala, S. S.; Simmons, B. D.; Snyder, C.; Garon, A.; Seymour, N.; Middelberg, E.; Andernach, H.; Lintott, C. J.; Jacob, K.; Kapińska, A. D.; Mao, M. Y.; Masters, K. L.; Jarvis, M. J.; Schawinski, K.; Paget, E.; Simpson, R.; Klöckner, H.-R.; Bamford, S.; Burchell, T.; Chow, K. E.; Cotter, G.; Fortson, L.; Heywood, I.; Jones, T. W.; Kaviraj, S.; López-Sánchez, Á. R.; Maksym, W. P.; Polsterer, K.; Borden, K.; Hollow, R. P.; Whyte, L.

    2015-11-01

    We present results from the first 12 months of operation of Radio Galaxy Zoo, which upon completion will enable visual inspection of over 170 000 radio sources to determine the host galaxy of the radio emission and the radio morphology. Radio Galaxy Zoo uses 1.4 GHz radio images from both the Faint Images of the Radio Sky at Twenty Centimeters (FIRST) and the Australia Telescope Large Area Survey (ATLAS) in combination with mid-infrared images at 3.4 μm from the Wide-field Infrared Survey Explorer (WISE) and at 3.6 μm from the Spitzer Space Telescope. We present the early analysis of the WISE mid-infrared colours of the host galaxies. For images in which there is >75 per cent consensus among the Radio Galaxy Zoo cross-identifications, the project participants are as effective as the science experts at identifying the host galaxies. The majority of the identified host galaxies reside in the mid-infrared colour space dominated by elliptical galaxies, quasi-stellar objects and luminous infrared radio galaxies. We also find a distinct population of Radio Galaxy Zoo host galaxies residing in a redder mid-infrared colour space consisting of star-forming galaxies and/or dust-enhanced non-star-forming galaxies consistent with a scenario of merger-driven active galactic nuclei (AGN) formation. The completion of the full Radio Galaxy Zoo project will measure the relative populations of these hosts as a function of radio morphology and power while providing an avenue for the identification of rare and extreme radio structures. Currently, we are investigating candidates for radio galaxies with extreme morphologies, such as giant radio galaxies, late-type host galaxies with extended radio emission and hybrid morphology radio sources.

  11. Stacking for machine learning redshifts applied to SDSS galaxies

    CERN Document Server

    Zitlau, Roman; Paech, Kerstin; Weller, Jochen; Rau, Markus Michael; Seitz, Stella

    2016-01-01

    We present an analysis of a general machine learning technique called 'stacking' for the estimation of photometric redshifts. Stacking techniques can feed the photometric redshift estimate, as output by a base algorithm, back into the same algorithm as an additional input feature in a subsequent learning round. We shown how all tested base algorithms benefit from at least one additional stacking round (or layer). To demonstrate the benefit of stacking, we apply the method to both unsupervised machine learning techniques based on self-organising maps (SOMs), and supervised machine learning methods based on decision trees. We explore a range of stacking architectures, such as the number of layers and the number of base learners per layer. Finally we explore the effectiveness of stacking even when using a successful algorithm such as AdaBoost. We observe a significant improvement of between 1.9% and 21% on all computed metrics when stacking is applied to weak learners (such as SOMs and decision trees). When appl...

  12. Stacking for machine learning redshifts applied to SDSS galaxies

    Science.gov (United States)

    Zitlau, Roman; Hoyle, Ben; Paech, Kerstin; Weller, Jochen; Rau, Markus Michael; Seitz, Stella

    2016-08-01

    We present an analysis of a general machine learning technique called `stacking' for the estimation of photometric redshifts. Stacking techniques can feed the photometric redshift estimate, as output by a base algorithm, back into the same algorithm as an additional input feature in a subsequent learning round. We show how all tested base algorithms benefit from at least one additional stacking round (or layer). To demonstrate the benefit of stacking, we apply the method to both unsupervised machine learning techniques based on self-organizing maps (SOMs), and supervised machine learning methods based on decision trees. We explore a range of stacking architectures, such as the number of layers and the number of base learners per layer. Finally we explore the effectiveness of stacking even when using a successful algorithm such as AdaBoost. We observe a significant improvement of between 1.9 per cent and 21 per cent on all computed metrics when stacking is applied to weak learners (such as SOMs and decision trees). When applied to strong learning algorithms (such as AdaBoost) the ratio of improvement shrinks, but still remains positive and is between 0.4 per cent and 2.5 per cent for the explored metrics and comes at almost no additional computational cost.

  13. Machine Learning based photometric redshifts for the KiDS ESO DR2 galaxies

    CERN Document Server

    Cavuoti, Stefano; Tortora, Crescenzo; Longo, Giuseppe; Napolitano, Nicola R; Radovich, Mario; La Barbera, Francesco; Capaccioli, Massimo; de Jong, Jelte T A; Getman, Fedor; Grado, Aniello; Paolillo, Maurizio

    2015-01-01

    We estimated photometric redshifts (zphot) for more than 1.1 million galaxies of the ESO Public Kilo-Degree Survey (KiDS) Data Release 2. KiDS is an optical wide-field imaging survey carried out with the VLT Survey Telescope (VST) and the OmegaCAM camera, which aims at tackling open questions in cosmology and galaxy evolution, such as the origin of dark energy and the channel of galaxy mass growth. We present a catalogue of photometric redshifts obtained using the Multi Layer Perceptron with Quasi Newton Algorithm (MLPQNA) model, provided within the framework of the DAta Mining and Exploration Web Application REsource (DAMEWARE). These photometric redshifts are based on a spectroscopic knowledge base which was obtained by merging spectroscopic datasets from GAMA (Galaxy And Mass Assembly) data release 2 and SDSS-III data release 9. The overall 1 sigma uncertainty on Delta z = (zspec - zphot) / (1+ zspec) is ~ 0.03, with a very small average bias of ~ 0.001, a NMAD of ~ 0.02 and a fraction of catastrophic outl...

  14. Photometric Redshifts and Morphologies of Galaxies in the NICMOS Parallel Fields

    CERN Document Server

    Corbin, M R; O'Neill, E; Thompson, R I; Rieke, M J; Schneider, G

    1999-01-01

    We present positions, magnitudes, sizes and morphological classifications for 111 galaxies discovered in the Hubble Space Telescope NICMOS Camera 1 and Camera 2 parallel fields. We combine the magnitudes measured in the JHK-analog filters with those from deep ground-based images in V and/or R to measure photometric redshifts for 71 objects using Bruzual-Charlot population synthesis models. We find that these objects fall in the range z ~ 0.0 - 2.7, with a mean redshift of 0.8 and a mean luminosity of 1.6 L*. The NICMOS images reveal many of the objects to be ordered spirals and ellipticals similar to those in the local universe. However, we find a higher fraction (~ 14%) of morphologically peculiar and/or interacting galaxies than is observed among local galaxies (~ 3% - 4%). This is consistent with the results from other deep HST images including the Hubble Deep Field and Hubble Medium Deep Survey Field that the fraction of peculiar and interacting galaxies increases with redshift. As the NICMOS images of th...

  15. CLASH: accurate photometric redshifts with 14 HST bands in massive galaxy cluster cores

    Science.gov (United States)

    Molino, A.; Benítez, N.; Ascaso, B.; Coe, D.; Postman, M.; Jouvel, S.; Host, O.; Lahav, O.; Seitz, S.; Medezinski, E.; Rosati, P.; Schoenell, W.; Koekemoer, A.; Jimenez-Teja, Y.; Broadhurst, T.; Melchior, P.; Balestra, I.; Bartelmann, M.; Bouwens, R.; Bradley, L.; Czakon, N.; Donahue, M.; Ford, H.; Graur, O.; Graves, G.; Grillo, C.; Infante, L.; Jha, S. W.; Kelson, D.; Lazkoz, R.; Lemze, D.; Maoz, D.; Mercurio, A.; Meneghetti, M.; Merten, J.; Moustakas, L.; Nonino, M.; Orgaz, S.; Riess, A.; Rodney, S.; Sayers, J.; Umetsu, K.; Zheng, W.; Zitrin, A.

    2017-09-01

    We present accurate photometric redshifts for galaxies observed by the Cluster Lensing And Supernova survey with Hubble (CLASH). CLASH observed 25 massive galaxy cluster cores with the Hubble Space Telescope in 16 filters spanning 0.2-1.7 μm. Photometry in such crowded fields is challenging. Compared to our previously released catalogues, we make several improvements to the photometry, including smaller apertures, intracluster light subtraction, point spread function matching and empirically measured uncertainties. We further improve the Bayesian photometric redshift estimates by adding a redder elliptical template and by inflating the photometric uncertainties of the brightest galaxies. The resulting photometric redshift accuracies are dz/(1+z) ∼ 0.8, 1.0 and 2.0 per cent for galaxies with I-band F814W AB magnitudes public lens models. Our new catalogue of all 25 CLASH clusters is available via Mikulski Archive for Space Telescopes. The analysis techniques developed here will be useful in other surveys of crowded fields, including the Frontier Fields and surveys carried out with Javalambre-Physics of the Accelerated Universe Astrophysical Survey and James Webb Space Telescope.

  16. Bulgeless Galaxies at Intermediate Redshift: Sample Selection, Colour Properties, and the Existence of Powerful AGN

    CERN Document Server

    Bizzocchi, Luca; Leonardo, Elvira; Grossi, Marco; Griffith, Roger L; Afonso, José; Fernandes, Cristina; Retrê, João; Anton, Sonia; Bell, Eric F; Brinchmann, Jarle; Henriques, Bruno; Lobo, Catarina; Messias, Hugo

    2014-01-01

    We present a catalogue of bulgeless galaxies, which includes 19225 objects selected in four of the deepest, largest multi-wavelength datasets available -- COSMOS, AEGIS, GEMS and GOODS -- at intermediate redshift ($0.4 \\leq z \\leq 1.0$). The morphological classification was provided by the Advanced Camera for Surveys General Catalogue (ACS-GC), which used publicly available data obtained with the ACS instrument on the Hubble Space Telescope. Rest-frame photometric quantities were derived using kcorrect. We analyse the properties of the sample and the evolution of pure-disc systems with redshift. Very massive [$\\log (M_\\star/M_{\\odot}) > 10.5$] bulgeless galaxies contribute to ~30% of the total galaxy population number density at $z \\geq 0.7$, but their number density drops substantially with decreasing redshift. We show that only a negligible fraction of pure discs appear to be quiescent systems, and red sequence bulgeless galaxies show indications of dust-obscured star formation. X-ray catalogues were used t...

  17. Bayesian Redshift Classification of Emission-line Galaxies with Photometric Equivalent Widths

    CERN Document Server

    Leung, Andrew S; Gawiser, Eric; Ciardullo, Robin; Komatsu, Eiichiro; Zeimann, Gregory R; Bridge, Joanna S; Feldmeier, John J; Finkelstein, Steven L; Gebhardt, Karl; Gronwall, Caryl; Hagen, Alex; Hill, Gary J; Schneider, Donald P

    2015-01-01

    We present a Bayesian approach to the redshift classification of emission-line galaxies when only a single emission line is detected spectroscopically. We consider the case of surveys for high-redshift ${\\rm Ly{\\alpha}}$-emitting galaxies (LAEs), which have traditionally been classified via an inferred rest-frame equivalent width $(W_{\\rm Ly\\alpha})$ greater than $20 {\\rm \\,\\AA}$. Our Bayesian method relies on known prior probabilities in measured emission-line luminosity functions and equivalent width distributions for the galaxy populations in question, and it returns the probability that an object is an LAE given the characteristics observed. This approach will be directly relevant for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), which seeks to classify $\\sim$$10^6$ emission-line galaxies into LAEs and low-redshift [O II] emitters. For a simulated HETDEX catalog with realistic measurement noise, our Bayesian method recovers $86\\%$ of LAEs missed by the traditional $W_{\\rm Ly\\alpha} > 20 {\\rm...

  18. Spectroscopic confirmation of two Lyman break galaxies at redshift beyond 7

    CERN Document Server

    Vanzella, E; Fontana, A; Grazian, A; Castellano, M; Boutsia, K; Cristiani, S; Dickinson, M; Gallozzi, S; Giallongo, E; Giavalisco, M; Maiolino, R; Moorwood, A; Paris, D; Santini, P

    2010-01-01

    We report the spectroscopic confirmation of two Lyman break galaxies at redshift > 7. The galaxies were observed as part of an utra-deep spectroscopic campaign with FORS2 at the ESO/VLT for the confirmation of z~7 "z--band dropout'' candidates selected from our VLT/Hawk-I imaging survey. Both galaxies show a prominent emission line at 9735A and 9858A respectively: the lines have fluxes around ~ 1-1.2 x 10^(-17) erg/s/cm2 and exhibit a sharp decline on the blue side and a tail on the red side. The asymmetry is quantitatively comparable to the observed asymmetry in z~6 Lya lines, where absorption by neutral hydrogen in the IGM truncates the blue side of the emission line profile. We carefully evaluate the possibility that the galaxies are instead at lower redshift and we are observing either [OII], [OIII] or Ha emission: however from the spectroscopic and the photometric data we conclude that there are no other plausible identifications, except for Lya at redshift > 7, making these the first robust Lyman break ...

  19. The distribution of neutral hydrogen around high-redshift galaxies and quasars in the EAGLE simulation

    CERN Document Server

    Rahmati, Alireza; Bower, Richard G; Crain, Robert A; Furlong, Michelle; Schaller, Matthieu; Theuns, Tom

    2015-01-01

    The observed high covering fractions of neutral hydrogen (HI) with column densities above $\\sim 10^{17} \\rm{cm}^{-2}$ around Lyman-Break Galaxies (LBGs) and bright quasars at redshifts z ~ 2-3 has been identified as a challenge for simulations of galaxy formation. We use the EAGLE cosmological, hydrodynamical simulation, which has been shown to reproduce a wide range of galaxy properties and for which the subgrid feedback was calibrated without considering gas properties, to study the distribution of HI around high-redshift galaxies. We predict the covering fractions of strong HI absorbers ($N_{\\rm{HI}} \\gtrsim 10^{17} \\rm{cm}^{-2}$) inside haloes to increase rapidly with redshift but to depend only weakly on halo mass. For massive ($M_{200} \\gtrsim 10^{12} {\\rm M_{\\odot}}$) halos the covering fraction profiles are nearly scale-invariant and we provide fitting functions that reproduce the simulation results. While efficient feedback is required to increase the HI covering fractions to the high observed values...

  20. The Hubble Diagram of Type Ia Supernovae as a Function of Host Galaxy Morphology

    CERN Document Server

    Sullivan, M; Aldering, G; Amanullah, R; Astier, Pierre; Blanc, G; Burns, M S; Conley, A; Deustua, S E; Doi, M; Fabbro, S; Folatelli, G; Fruchter, A S; Garavini, G; Gibbons, R; Goldhaber, Gerson; Goobar, A; Groom, D E; Hardin, D; Hook, I; Howell, D A; Irwin, M; Kim, A G; Knop, R A; Lidman, C E; McMahon, R; Méndez, J; Nobili, S; Nugent, P; Pain, R; Panagia, N; Pennypacker, C R; Perlmutter, S; Quimby, R; Raux, J; Regnault, N; Ruiz-Lapuente, P; Schaefer, B; Schahmaneche, K; Spadafora, A L; Walton, N A; Wang, L; Wood-Vasey, W M; Yasuda, N

    2003-01-01

    (Abridged) We present new results on the Hubble diagram of distant type Ia supernovae (SNe Ia) segregated according to the type of host galaxy. This makes it possible to check earlier evidence for a cosmological constant by explicitly comparing SNe residing in galaxies likely to contain negligible dust with the larger sample. The cosmological parameters derived from these SNe Ia hosted by presumed dust-free early-type galaxies supports earlier claims for a cosmological constant, which we demonstrate at 5 sigma significance, and the internal extinction implied is small even for late-type systems (A_B<0.2). Thus, our data demonstrate that host galaxy extinction is unlikely to systematically dim distant SNe Ia in a manner that would produce a spurious cosmological constant. We classify the host galaxies of 39 distant SNe discovered by the Supernova Cosmology Project (SCP) using the combination of HST STIS imaging, Keck ESI spectroscopy and ground-based broad-band photometry. We compare with a low-redshift sam...

  1. On the [CII]-SFR relation in high redshift galaxies

    CERN Document Server

    Vallini, L; Ferrara, A; Pallottini, A; Yue, B

    2015-01-01

    After two ALMA observing cycles, only a handful of [CII] $158\\,\\mu m$ emission line searches in z>6 galaxies have reported a positive detection, questioning the applicability of the local [CII]-SFR relation to high-z systems. To investigate this issue we use the Vallini et al. 2013 (V13) model, based on high-resolution, radiative transfer cosmological simulations to predict the [CII] emission from the interstellar medium of a z~7 (halo mass $M_h=1.17\\times10^{11}M_{\\odot}$) galaxy. We improve the V13 model by including (a) a physically-motivated metallicity (Z) distribution of the gas, (b) the contribution of Photo-Dissociation Regions (PDRs), (c) the effects of Cosmic Microwave Background on the [CII] line luminosity. We study the relative contribution of diffuse neutral gas to the total [CII] emission ($F _{diff}/F_{tot}$) for different SFR and Z values. We find that the [CII] emission arises predominantly from PDRs: regardless of the galaxy properties, $F _{diff}/F_{tot}\\leq 10$% since, at these early epoc...

  2. Chandra Multiwavelength Project: Normal Galaxies at Intermediate Redshift

    CERN Document Server

    Kim, D W; Colmenero, E R; Green, P J; Kim, M; Mossman, A; Schlegel, E M; Silverman, J D; Aldcroft, T; Ivezic, Z; Anderson, C; Kashyap, V; Tananbaum, H; Wilkes, B J

    2005-01-01

    (abridged) We have investigated 136 Chandra extragalactic sources without broad optical emission lines, including 93 galaxies with narrow emission lines (NELG) and 43 with only absorption lines (ALG). Based on fx/fo, Lx, X-ray spectral hardness and optical emission line diagnostics, we have conservatively classified 36 normal galaxies (20 spirals and 16 ellipticals) and 71 AGNs. We found no statistically significant evolution in Lx/LB, within the limited z range. We have built log(N)-log(S), after correcting for completeness based on a series of simulations. The best-fit slope is -1.5 for both S and B energy bands, which is considerably steeper than that of the AGN-dominated cosmic background sources, but slightly flatter than the previous estimate, indicating normal galaxies will not exceed the AGN population until fx ~ 2 x 10-18 erg s-1 cm-2 (a factor of ~5 lower than the previous estimate). A group of NELGs appear to be heavily obscured in X-rays, i.e., a typical type 2 AGN. After correcting for intrinsic ...

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

    Science.gov (United States)

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

    2016-12-01

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

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

    CERN Document Server

    Atlee, David W

    2012-01-01

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

  5. Reconstruction of halo power spectrum from redshift-space galaxy distribution: cylinder-grouping method and halo exclusion effect

    CERN Document Server

    Okumura, Teppei; More, Surhud; Masaki, Shogo

    2016-01-01

    The peculiar velocity field measured by redshift-space distortions (RSD) in galaxy surveys provides a unique probe of the growth of large-scale structure. However, systematic effects arise when including satellite galaxies in the clustering analysis. Since satellite galaxies tend to reside in massive halos with a greater halo bias, the inclusion boosts the clustering power. In addition, virial motions of the satellite galaxies cause a significant suppression of the clustering power due to nonlinear RSD effects. We develop a novel method to recover the redshift-space power spectrum of halos from the observed galaxy distribution by minimizing the contamination of satellite galaxies. The cylinder grouping method (CGM) we study effectively excludes satellite galaxies from a galaxy sample. However, we find that this technique produces apparent anisotropies in the reconstructed halo distribution over all the scales which mimic RSD. On small scales, the apparent anisotropic clustering is caused by exclusion of halos...

  6. The Luminous Polycyclic Aromatic Hydrocarbon Emission Features: Applications to High Redshift Galaxies and Active Galactic Nuclei

    Science.gov (United States)

    Shipley, Heath V.

    2016-01-01

    For decades, significant work has been applied to calibrating emission from the ultra-violet, nebular emission lines, far-infrared, X-ray and radio as tracers of the star-formation rate (SFR) in distant galaxies. Understanding the exact rate of star-formation and how it evolves with time and galaxy mass has deep implications for how galaxies form. The co-evolution of star-formation and supermassive black hole (SMBH) accretion is one of the key problems in galaxy formation theory. But, many of these SFR indicators are influenced by SMBH accretion in galaxies and result in unreliable SFRs. Utilizing the luminous polycyclic aromatic hydrocarbon (PAH) emission features, I provide a new robust SFR calibration using the luminosity emitted from the PAHs at 6.2μm, 7.7μm and 11.3μm to solve this. The PAH features emit strongly in the mid-infrared (mid-IR; 5-25μm) mitigating dust extinction, containing on average 5-10% of the total IR luminosity in galaxies. I use a sample of 105 star-forming galaxies covering a range of total IR luminosity, LIR = L(8-1000μm) = 109 - 1012 L⊙ and redshift 0 blackhole accretion contemporaneously in a galaxy.

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

    Science.gov (United States)

    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.

  8. Velocity anti-correlation of diametrically opposed galaxy satellites in the low-redshift Universe.

    Science.gov (United States)

    Ibata, Neil G; Ibata, Rodrigo A; Famaey, Benoit; Lewis, Geraint F

    2014-07-31

    Recent work has shown that the Milky Way and the Andromeda galaxies both possess the unexpected property that their dwarf satellite galaxies are aligned in thin and kinematically coherent planar structures. It is interesting to evaluate the incidence of such planar structures in the larger galactic population, because the Local Group may not be a representative environment. Here we report measurements of the velocities of pairs of diametrically opposed satellite galaxies. In the local Universe (redshift z 7σ confidence). This may indicate that planes of co-rotating satellites, similar to those seen around the Andromeda galaxy, are ubiquitous, and their coherent motion suggests that they represent a substantial repository of angular momentum on scales of about 100 kiloparsecs.

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

    CERN Document Server

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

    2005-01-01

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

  10. Velocity anti-correlation of diametrically opposed galaxy satellites in the low redshift universe

    CERN Document Server

    Ibata, Neil G; Famaey, Benoit; Lewis, Geraint F

    2014-01-01

    Recent work has shown that both the Milky Way and the Andromeda galaxies possess the unexpected property that their dwarf satellite galaxies are aligned in thin and kinematically coherent planar structures. It is now important to evaluate the incidence of such planar structures in the larger galactic population, since the Local Group may not be a sufficiently representative environment. Here we report that the measurement of the velocity of pairs of diametrically opposed galaxy satellites provides a means to determine statistically the prevalence of kinematically coherent planar alignments. In the local universe (redshift $z7\\sigma$ confidence). Our finding may indicate that co-rotating planes of satellites, similar to that seen around the Andromeda galaxy, are ubiquitous in nature, while their coherent motion also suggests that they are a significant repository of angular momentum on $\\sim 100$ kpc scales.

  11. ACTIVE GALACTIC NUCLEI AS MAIN CONTRIBUTORS TO THE ULTRAVIOLET IONIZING EMISSIVITY AT HIGH REDSHIFTS: PREDICTIONS FROM A {Lambda}-CDM MODEL WITH LINKED AGN/GALAXY EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Giallongo, E.; Menci, N.; Fiore, F.; Castellano, M.; Fontana, A.; Grazian, A.; Pentericci, L. [INAF-Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio (Italy)

    2012-08-20

    We have evaluated the contribution of the active galactic nuclei (AGN) population to the ionization history of the universe based on a semi-analytic model of galaxy formation and evolution in the cold dark matter cosmological scenario. The model connects the growth of black holes and of the ensuing AGN activity to galaxy interactions. In the model we have included a self-consistent physical description of the escape of ionizing UV photons; this is based on the blast-wave model for the AGN feedback we developed in a previous paper to explain the distribution of hydrogen column densities in AGNs of various redshifts and luminosities, due to absorption by the host galaxy gas. The model predicts UV luminosity functions for AGNs that are in good agreement with those derived from the observations especially at low and intermediate redshifts (z {approx} 3). At higher redshifts (z > 5), the model tends to overestimate the data at faint luminosities. Critical biases in both the data and in the model are discussed to explain such apparent discrepancies. The predicted hydrogen photoionization rate as a function of redshift is found to be consistent with that derived from the observations. All of the above suggests that we should reconsider the role of the AGNs as the main driver of the ionization history of the universe.

  12. Magellan LDSS3 emission confirmation of galaxies hosting metal-rich Lyman-alpha absorption systems

    CERN Document Server

    Straka, Lorrie A; York, Donald G; Bowen, David V; Florian, Michael; Kulkarni, Varsha P; Lundgren, Britt; Peroux, Celine

    2015-01-01

    Using the Low Dispersion Survey Spectrograph 3 at the Magellan II Clay Telescope in Chile, we target candidate absorption host galaxies detected in deep optical imaging (reaching limiting apparent magnitudes of 23.0-26.5 in g; r; i; and z filters) in the fields of three QSOs, each of which shows the presence of high metallicity, strong NHI absorption systems in their spectra (Q0826-2230: zabs=0.9110, Q1323-0021: zabs = 0.7160, Q1436-0051: zabs = 0.7377; 0.9281). We confirm host galaxies at redshifts 0.7387, 0.7401, and 0.9286 for two out of four of the Ly-alpha absorption systems. For these systems, we are able to determine the SFRs; impact parameters (known from previous imaging detections); the velocity shift between the absorption and emission redshifts; and, for one system, also the emission metallicity. Based on previous photometry, we find these galaxies have L>L*. The SFRs for these galaxies, based on [O II] emission, are in the range 11-25 M_sol/yr (uncorrected for dust), while the impact parameters l...

  13. The Rise and Fall of Star Formation Histories of Blue Galaxies at Redshifts 0.2 < z < 1.4

    Science.gov (United States)

    Pacifici, Camilla; Kassin, Susan A.; Weiner, Benjamin; Charlot, Stephane; Gardner, Jonathan P.

    2012-01-01

    Popular cosmological scenarios predict that galaxies form hierarchically from the merger of many progenitor, each with their own unique star formation history (SFH). We use the approach recently developed by Pacifici et al. to constrain the SFHs of 4517 blue (presumably star-forming) galaxies with spectroscopic redshifts in the range O.2 star formation and chemical enrichment histories, stellar population synthesis, nebular emission and attenuation by dust. We constrain the SFH of each galaxy in our sample by comparing the observed fluxes in the B, R,l and K(sub s) bands and rest-frame optical emission-line luminosities with those of one million model spectral energy distributions. We explore the dependence of the resulting SFH on galaxy stellar mass and redshift. We find that the average SFHs of high-mass galaxies rise and fall in a roughly symmetric bell-shaped manner, while those of low-mass galaxies rise progressively in time, consistent with the typically stronger activity of star formation in low-mass compared to high-mass galaxies. For galaxies of all masses, the star formation activity rises more rapidly at high than at low redshift. These findings imply that the standard approximation of exponentially declining SFHs wIdely used to interpret observed galaxy spectral energy distributions is not appropriate to constrain the physical parameters of star-forming galaxies at intermediate redshifts.

  14. Morphologies of z~0.7 AGN Host Galaxies in CANDELS: No trend of merger incidence with AGN luminosity

    CERN Document Server

    Villforth, C; Rosario, D J; Santini, P; McGrath, E J; van der Wel, A; Chang, Y -Y; Guo, Yicheng; Dahlen, T; Bell, E F; Conselice, C J; Croton, D; Dekel, A; Faber, S M; Grogin, N; Hamilton, T; Hopkins, P F; Juneau, S; Kartaltepe, J; Kocevski, D; Koekemoer, A; Koo, D C; Lotz, J; McIntosh, D; Mozena, M; Somerville, R; Wild, V

    2014-01-01

    The processes that trigger Active Galactic Nuclei (AGN) remain poorly understood. While lower luminosity AGN may be triggered by minor disturbances to the host galaxy, stronger disturbances are likely required to trigger luminous AGN. Major wet mergers of galaxies are ideal environments for AGN triggering since they provide large gas supplies and galaxy scale torques. There is however little observational evidence for a strong connection between AGN and major mergers. We analyse the morphological properties of AGN host galaxies as a function of AGN and host galaxy luminosity and compare them to a carefully matched sample of control galaxies. AGN are X-ray selected in the redshift range 0.5 < z < 0.8 and have luminosities 41 < log(L_X [erg/s]) < 44.5. 'Fake AGN' are simulated in the control galaxies by adding point sources with the magnitude of the matched AGN. We find that AGN host and control galaxies have comparable assymetries, Sersic indices and ellipticities at restframe ~950nm. AGN host gala...

  15. Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies

    CERN Document Server

    Izotov, Y I; Thuan, T X; Worseck, G; Orlitova, I; Verhamme, A

    2016-01-01

    Following our first detection reported in Izotov et al. (2016), we present the detection of Lyman continuum (LyC) radiation of four other compact star-forming galaxies observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST). These galaxies, at redshifts of z~0.3, are characterized by high emission-line flux ratios [OIII]5007/[OII]3727 > 5. The escape fractions of the LyC radiation fesc(LyC) in these galaxies are in the range of ~6%-13%, the highest values found so far in low-redshift star-forming galaxies. Narrow double-peaked Lyalpha emission lines are detected in the spectra of all four galaxies, compatible with predictions for Lyman continuum leakers. We find escape fractions of Lyalpha, fesc(Lyalpha) ~60%-90%, among the highest known for Lyalpha emitters (LAEs). Surface brightness profiles produced from the COS acquisition images reveal bright star-forming regions in the center and exponential discs in the outskirts with disc scale lengths alpha in the range ~0.6-1.4 k...

  16. Atomic carbon as a tracer of molecular gas in high-redshift galaxies: perspectives for ALMA

    CERN Document Server

    Tomassetti, Matteo; Romano-Diaz, Emilio; Ludlow, Aaron D; Papadopoulos, Padelis P

    2014-01-01

    We use a high-resolution simulation that tracks the non-equilibrium abundance of molecular hydrogen, H2, within a massive high-redshift galaxy to produce mock ALMA maps of the fine-structure lines of atomic carbon CI 1-0 and CI 2-1. Inspired by recent observational and theoretical work, we assume that CI is thoroughly mixed in giant molecular clouds and demonstrate that its emission is an excellent proxy for H2. The entire H2 mass of a galaxy at redshift z<4 can be detected using a compact interferometric configuration with a large synthesized beam (that does not resolve the target galaxy) in less than 1 hour of integration time. Low-resolution imaging of the CI lines (in which the target galaxy is resolved into 3-4 beams) will detect nearly 50-60 per cent of the molecular hydrogen in less than 12 hours. In this case, the data cube also provides valuable information regarding the dynamical state of the galaxy. We conclude that ALMA observations of the CI 1-0 and 2-1 emission will widely extend the interval...

  17. High redshift evolution of optically and IR-selected galaxies a comparison with CDM scenarios

    CERN Document Server

    Fontana, A; D'Odorico, S; Giallongo, E; Poli, F; Cristiani, S; Moorwood, A F M; Saracco, P

    1999-01-01

    A combination of ground-based (NTT and VLT) and HST (HDF-N and HDF-S) public imaging surveys have been used to collect a sample of 1712 I-selected and 319 $K\\leq 21$ galaxies. Photometric redshifts have been obtained for all these galaxies. The results have been compared with the prediction of an analytic rendition of the current CDM hierarchical models for galaxy formation. We focus in particular on two observed quantities: the galaxy redshift distribution at K2. This result strongly supports hierarchical scenarios where present-day massive galaxies are the result of merging processes. The observed UV luminosity density in the I-selected sample is confined within a factor of 4 over the whole range 03. CDM models in $\\Lambda$-dominated universe are in better agreement at 3

  18. The effects of UV photometry and binary interactions on photometric redshift and galaxy morphology

    CERN Document Server

    Zhang, F; Li, L; Shan, H; Zhang, Y

    2010-01-01

    Using the Hyperz code and a template spectral library which consists of 4 observed galaxy spectra from Coleman, Wu & Weedman (CWW, 1980) and 8 spectral families built with evolutionary population synthesis models, we present photometric redshift estimates (photo-z) for a spectroscopic sample of 6,531 galaxies, and morphologies for a morphological sample of 1,502 bright galaxies. All galaxies are matched with the SDSS DR7 and GALEX DR4. The inclusion of Fuv or Nuv or both photometry decreases the number of catastrophic identifications (CIs, |z_phot -z_spec| > 1.0). If CIs are removed, the inclusion of both Fuv and Nuv photometry mainly increases the number of non-CIs in the low redshift, g-r 14 regions. Moreover, BIs mainly affect the determinations of E and S0 types. Nuv -u = 1.94 and 5.77-1.47(u-r) = Fuv discriminators can be used as morphology selection indicators. These two criteria have comparable reliability and completeness for selecting early- and late-type galaxies to C=2.6 criterion and higher c...

  19. Clustering analysis of high-redshift Luminous Red Galaxies in Stripe 82

    CERN Document Server

    Nikoloudakis, Nikolaos; Sawangwit, Utane

    2012-01-01

    We present a clustering analysis of Luminous Red Galaxies (LRGs) in SDSS Stripe 82. We study the angular 2-point correlation function, w(theta), of 130,000 LRG candidates via colour-cut selections in izK with the K band coverage coming from UKIDSS LAS. We have used the cross-correlation technique of Newman (2008) to establish the LRG redshift distribution. Cross-correlating with SDSS QSOs, MegaZ-LRGs and DEEP2 galaxies implies an average LRG redshift of z~1 with space density, n_g~3.2x10^-4 h^3 Mpc^-3. For theta 50 h^-1 Mpc. If this result is not caused by systematics, then it may provide evidence for primordial non-Gaussianity in the matter distribution, with f^local_NL=90+/-30.

  20. The Efficacy of Galaxy Shape Parameters in Photometric Redshift Estimation: A Neural Network Approach

    Energy Technology Data Exchange (ETDEWEB)

    Singal, J.; Shmakova, M.; Gerke, B.; /KIPAC, Menlo Park /SLAC /Stanford U.; Griffith, R.L.; /Caltech, JPL; Lotz, J.; /NOAO, Tucson

    2011-05-20

    We present a determination of the effects of including galaxy morphological parameters in photometric redshift estimation with an artificial neural network method. Neural networks, which recognize patterns in the information content of data in an unbiased way, can be a useful estimator of the additional information contained in extra parameters, such as those describing morphology, if the input data are treated on an equal footing. We show that certain principal components of the morphology information are correlated with galaxy type. However, we find that for the data used the inclusion of morphological information does not have a statistically significant benefit for photometric redshift estimation with the techniques employed here. The inclusion of these parameters may result in a trade-off between extra information and additional noise, with the additional noise becoming more dominant as more parameters are added.

  1. Simulating the assembly of galaxies at redshifts z = 6 - 12

    CERN Document Server

    Dayal, Pratika; Maio, Umberto; Ciardi, Benedetta

    2012-01-01

    We use state-of-the-art simulations to explore the physical evolution of galaxies in the first billion years of cosmic time. First, we demonstrate that our model, without any tuning, reproduces the basic statistical properties of the observed Lyman-break galaxy (LBG) population at z = 6 - 8, including the evolving ultra-violet (UV) luminosity function (LF), the stellar-mass density (SMD), and the average specific star-formation rates (sSFR) of LBGs with M_{UV} < -18 (AB mag). Encouraged by this success we present predictions for the behaviour of fainter LBGs extending down to M_{UV} <= -15 (as will be probed with the James Webb Space Telescope) and have interrogated our simulations to try to gain insight into the physical drivers of the observed population evolution. We find that mass growth due to star formation in the mass-dominant progenitor builds up about 90% of the total z ~ 6 LBG stellar mass, dominating over the mass contributed by merging throughout this era. Our simulation suggests that the ap...

  2. The rest-frame submillimeter spectrum of high-redshift, dusty, star-forming galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Spilker, J. S.; Marrone, D. P. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Aguirre, J. E. [University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Aravena, M. [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001 Vitacura Santiago (Chile); Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Béthermin, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Université Paris Diderot, CEA-Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Bradford, C. M. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Bothwell, M. S. [Cavendish Laboratory, University of Cambridge, JJ Thompson Ave, Cambridge CB3 0HA (United Kingdom); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Carlstrom, J. E.; Crawford, T. M. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Chapman, S. C. [Dalhousie University, Halifax, Nova Scotia (Canada); De Breuck, C.; Gullberg, B. [European Southern Observatory, Karl Schwarzschild Straße 2, D-85748 Garching (Germany); Fassnacht, C. D. [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Gonzalez, A. H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Hezaveh, Y. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Holzapfel, W. L., E-mail: jspilker@as.arizona.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States); and others

    2014-04-20

    We present the average rest-frame spectrum of high-redshift dusty, star-forming galaxies from 250 to 770 GHz. This spectrum was constructed by stacking Atacama Large Millimeter/submillimeter Array (ALMA) 3 mm spectra of 22 such sources discovered by the South Pole Telescope and spanning z = 2.0-5.7. In addition to multiple bright spectral features of {sup 12}CO, [C I], and H{sub 2}O, we also detect several faint transitions of {sup 13}CO, HCN, HNC, HCO{sup +}, and CN, and use the observed line strengths to characterize the typical properties of the interstellar medium of these high-redshift starburst galaxies. We find that the {sup 13}CO brightness in these objects is comparable to that of the only other z > 2 star-forming galaxy in which {sup 13}CO has been observed. We show that the emission from the high-critical density molecules HCN, HNC, HCO{sup +}, and CN is consistent with a warm, dense medium with T {sub kin} ∼ 55 K and n{sub H{sub 2}}≳10{sup 5.5} cm{sup –3}. High molecular hydrogen densities are required to reproduce the observed line ratios, and we demonstrate that alternatives to purely collisional excitation are unlikely to be significant for the bulk of these systems. We quantify the average emission from several species with no individually detected transitions, and find emission from the hydride CH and the linear molecule CCH for the first time at high redshift, indicating that these molecules may be powerful probes of interstellar chemistry in high-redshift systems. These observations represent the first constraints on many molecular species with rest-frame transitions from 0.4 to 1.2 mm in star-forming systems at high redshift, and will be invaluable in making effective use of ALMA in full science operations.

  3. Characterization and Modeling of Contamination for Lyman Break Galaxy Samples at High Redshift

    Science.gov (United States)

    Vulcani, Benedetta; Trenti, Michele; Calvi, Valentina; Bouwens, Rychard; Oesch, Pascal; Stiavelli, Massimo; Franx, Marijn

    2017-02-01

    The selection of high-redshift sources from broadband photometry using the Lyman-break galaxy (LBG) technique is a well established methodology, but the characterization of its contamination for the faintest sources is still incomplete. We use the optical and near-IR data from four (ultra)deep Hubble Space Telescope legacy fields to investigate the contamination fraction of LBG samples at z∼ 5{--}8 selected using a color–color method. Our approach is based on characterizing the number count distribution of interloper sources, that is, galaxies with colors similar to those of LBGs, but showing detection at wavelengths shorter than the spectral break. Without sufficient sensitivity at bluer wavelengths, a subset of interlopers may not be properly classified, and contaminate the LBG selection. The surface density of interlopers in the sky gets steeper with increasing redshift of LBG selections. Since the intrinsic number of dropouts decreases significantly with increasing redshift, this implies increasing contamination from misclassified interlopers with increasing redshift, primarily by intermediate redshift sources with unremarkable properties (intermediate ages, lack of ongoing star formation and low/moderate dust content). Using Monte-Carlo simulations, we estimate that the CANDELS deep data have contamination induced by photometric scatter increasing from ∼ 2 % at z∼ 5 to ∼ 6 % at z∼ 8 for a typical dropout color ≥slant 1 mag, with contamination naturally decreasing for a more stringent dropout selection. Contaminants are expected to be located preferentially near the detection limit of surveys, ranging from 0.1 to 0.4 contaminants per arcmin2 at {J}125 = 30, depending on the field considered. This analysis suggests that the impact of contamination in future studies of z> 10 galaxies needs to be carefully considered.

  4. First redshift determination of an optically/UV faint submillimeter galaxy using CO emission lines

    CERN Document Server

    Weiss, A; Downes, D; Walter, F; Cirasuolo, M; Menten, K M

    2009-01-01

    We report the redshift of a distant, highly obscured submm galaxy (SMG), based entirely on the detection of its CO line emission. We have used the newly commissioned Eight-MIxer Receiver (EMIR) at the IRAM 30m telescope, with its 8 GHz of instantaneous dual-polarization bandwidth, to search the 3-mm atmospheric window for CO emission from SMMJ14009+0252, a bright SMG detected in the SCUBA Lens Survey. A detection of the CO(3--2) line in the 3-mm window was confirmed via observations of CO(5--4) in the 2-mm window. Both lines constrain the redshift of SMMJ14009+0252 to z=2.9344, with high precision (dz=2 10^{-4}). Such observations will become routine in determining redshifts in the era of the Atacama Large Millimeter/submillimeter Array (ALMA).

  5. High-precision Photometric Redshifts from Spitzer/IRAC: Extreme [3.6]-[4.5] Colors Identify Galaxies in the Redshift Range z~6.6-6.9

    CERN Document Server

    Smit, Renske; Franx, Marijn; Oesch, Pascal A; Ashby, Matthew L N; Willner, S P; Labbe, Ivo; Holwerda, Benne; Fazio, Giovanni G; Huang, J -S

    2014-01-01

    One of the most challenging aspects of studying galaxies in the z>~7 universe is the infrequent confirmation of their redshifts through spectroscopy, a phenomenon thought to occur from the increasing opacity of the intergalactic medium to Lya photons at z>6.5. The resulting redshift uncertainties inhibit the efficient search for [C II] in z~7 galaxies with sub-mm instruments such as ALMA, given their limited scan speed for faint lines. One means by which to improve the precision of the inferred redshifts is to exploit the potential impact of strong nebular emission lines on the colors of z~4-8 galaxies as observed by Spitzer/IRAC. At z~6.8, galaxies exhibit IRAC colors as blue as [3.6]-[4.5] ~-1, likely due to the contribution of [O III]+Hb to the 3.6 mum flux combined with the absence of line contamination in the 4.5 mum band. In this paper we explore the use of extremely blue [3.6]-[4.5] colors to identify galaxies in the narrow redshift window z~6.6-6.9. When combined with an I-dropout criterion, we demons...

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

    CERN Document Server

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

    2016-01-01

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

  7. From Nearby Low Luminosity AGN to High Redshift Radio Galaxies: Science Interests with Square Kilometre Array

    Indian Academy of Sciences (India)

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

    2016-12-01

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

  8. Large-scale clustering of galaxies in the CfA Redshift Survey

    Science.gov (United States)

    Vogeley, Michael S.; Park, Changbom; Geller, Margaret J.; Huchra, John P.

    1992-01-01

    The power spectrum of the galaxy distribution in the Center for Astrophysics Redshift Survey (de Lapparent et al., 1986; Geller and Huchra, 1989; and Huchra et al., 1992) is measured up to wavelengths of 200/h Mpc. Results are compared with several cosmological simulations with Gaussian initial conditions. It is shown that the power spectrum of the standard CDM model is inconsistent with the observed power spectrum at the 99 percent confidence level.

  9. WISE × SuperCOSMOS Photometric Redshift Catalog: 20 Million Galaxies over 3/pi Steradians

    Science.gov (United States)

    Bilicki, Maciej; Peacock, John A.; Jarrett, Thomas H.; Cluver, Michelle E.; Maddox, Natasha; Brown, Michael J. I.; Taylor, Edward N.; Hambly, Nigel C.; Solarz, Aleksandra; Holwerda, Benne W.; Baldry, Ivan; Loveday, Jon; Moffett, Amanda; Hopkins, Andrew M.; Driver, Simon P.; Alpaslan, Mehmet; Bland-Hawthorn, Joss

    2016-07-01

    We cross-match the two currently largest all-sky photometric catalogs—mid-infrared Wide-field Infrared Survey Explorer and SuperCOSMOS scans of UKST/POSS-II photographic plates—to obtain a new galaxy sample that covers 3π steradians. In order to characterize and purify the extragalactic data set, we use external GAMA and Sloan Digital Sky Survey spectroscopic information to define quasar and star loci in multicolor space, aiding the removal of contamination from our extended source catalog. After appropriate data cleaning, we obtain a deep wide-angle galaxy sample that is approximately 95% pure and 90% complete at high Galactic latitudes. The catalog contains close to 20 million galaxies over almost 70% of the sky, outside the Zone of Avoidance and other confused regions, with a mean surface density of more than 650 sources per square degree. Using multiwavelength information from two optical and two mid-IR photometric bands, we derive photometric redshifts for all the galaxies in the catalog, using the ANNz framework trained on the final GAMA-II spectroscopic data. Our sample has a median redshift of {z}{med}=0.2, with a broad {dN}/{dz} reaching up to z > 0.4. The photometric redshifts have a mean bias of | δ z| ˜ {10}-3, a normalized scatter of σ z = 0.033, and less than 3% outliers beyond 3σ z . Comparison with external data sets shows no significant variation of photo-z quality with sky position. Together with the overall statistics, we also provide a more detailed analysis of photometric redshift accuracy as a function of magnitudes and colors. The final catalog is appropriate for “all-sky” three-dimensional (3D) cosmology to unprecedented depths, in particular through cross-correlations with other large-area surveys. It should also be useful for source preselection and identification in forthcoming surveys, such as TAIPAN or WALLABY.

  10. Near-Infrared Properties of Moderate-Redshift Galaxy Clusters: Luminosity Functions and Density Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Muzzin, Adam; Yee, H.K.C.; /Toronto U., Astron. Dept.; Hall, Patrick B.; /York U., Canada; Ellingson, E.; /Colorado U., CASA; Lin, Huan; /Fermilab

    2006-12-01

    We present K-band imaging for 15 of the Canadian Network for Observational Cosmology (CNOC1) clusters. The extensive spectroscopic dataset available for these clusters allows us to determine the cluster K-band luminosity function and density profile without the need for statistical background subtraction. The luminosity density and number density profiles can be described by NFW models with concentration parameters of c{sub l} = 4.28 {+-} 0.70 and c{sub g} = 4.13 {+-} 0.57 respectively. Comparing these to the dynamical mass analysis of the same clusters shows that the galaxy luminosity and number density profiles are similar to the dark matter profile, and are not less concentrated like in local clusters. The luminosity functions show that the evolution of K. over the redshift range 0.2 < z < 0.5 is consistent with a scenario where the majority of stars in cluster galaxies form at high-redshift (z{sub f} > 1.5) and evolve passively thereafter. The best-fit for the faint-end slope of the luminosity function is {alpha} = -0.84 {+-} 0.08, which indicates that it does not evolve between z = 0 and z = 0.3. Using Principal Component Analysis of the spectra we classify cluster galaxies as either star-forming/recently-star-forming (EM+BAL) or non-star forming (ELL) and compute their respective luminosity functions. The faint-end slope of the ELL luminosity function is much shallower than for the EM+BAL galaxies at z = 0.3, and suggests the number of faint ELL galaxies in clusters decreases by a factor of {approx} 3 from z = 0 to z = 0.3. The redshift evolution of K* for both EM+BAL and ELL types is consistent with a passively evolving stellar population formed at high-redshift. Passive evolution in both classes, as well as the total cluster luminosity function, demonstrates that the bulk of the stellar population in all bright cluster galaxies is formed at high-redshift and subsequent transformations in morphology/color/spectral-type have little effect on the total stellar

  11. The redshift distribution of dusty star forming galaxies from the SPT survey

    CERN Document Server

    Strandet, M L; Vieira, J D; de Breuck, C; Aguirre, J E; Aravena, M; Ashby, M L N; Béthermin, M; Bradford, C M; Carlstrom, J E; Chapman, S C; Crawford, T M; Everett, W; Fassnacht, C D; Furstenau, R M; Gonzalez, A H; Greve, T R; Gullberg, B; Hezaveh, Y; Kamenetzky, J R; Litke, K; Ma, J; Malkan, M; Marrone, D P; Menten, K M; Murphy, E J; Nadolski, A; Rotermund, K M; Spilker, J S; Stark, A A; Welikala, N

    2016-01-01

    We use the Atacama Large Millimeter/submillimeter Array (ALMA) in Cycle 1 to determine spectroscopic redshifts of high-redshift dusty star-forming galaxies (DSFGs) selected by their 1.4mm continuum emission in the South Pole Telescope (SPT) survey. We present ALMA 3mm spectral scans between 84-114GHz for 15 galaxies and targeted ALMA 1mm observations for an additional eight sources. Our observations yield 30 new line detections from CO, [CI] , [NII] , H_2O and NH_3. We further present APEX [CII] and CO mid-J observations for seven sources for which only a single line was detected in spectral-scan data from ALMA Cycle 0 or Cycle 1. We combine the new observations with previously published and new mm/submm line and photometric data of the SPT-selected DSFGs to study their redshift distribution. The combined data yield 39 spectroscopic redshifts from molecular lines, a success rate of >85%. Our sample represents the largest data set of its kind today and has the highest spectroscopic completeness among all redsh...

  12. Measuring PAH Emission in Ultradeep Spitzer IRS Spectroscopy of High Redshift IR Luminous Galaxies

    CERN Document Server

    Teplitz, H I; Armus, L; Chary, R; Marshall, J A; Colbert, J W; Frayer, D T; Pope, A; Blain, A; Spoon, H; Charmandaris, V; Scott, D

    2007-01-01

    The study of the dominant population of high redshift IR-luminous galaxies (10^11 - 10^12 Lsun at 1redshift target were taken in the observed-frame 8--21 micron range, while the spectrum of the higher redshift target covered 21--37 microns. We also present the spectra of two secondary sources within the slit. We detect strong PAH emission in all four targets, and compare the spectra to those of local galaxies observed by the IRS. The z=1.09 source appears to be a typical, star-formation dominated IR-luminous galaxy, while the z=2.69 source is a composite source with strong star formation and a prominent AGN. The IRAC colors of this source show no evidence of rest-frame near-infrared stellar photospheric...

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

    Science.gov (United States)

    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.

  14. Interpreting the observed UV continuum slopes of high-redshift galaxies

    CERN Document Server

    Wilkins, Stephen M; Coulton, William; Croft, Rupert; Di Matteo, Tiziana; Khandai, Nishikanta; Feng, Yu

    2013-01-01

    The observed UV continuum slope of star forming galaxies is strongly affected by the presence of dust. Its observation is then a potentially valuable diagnostic of dust attenuation, particularly at high-redshift where other diagnostics are currently inaccesible. Interpreting the observed UV continuum slope in the context of dust attenuation is often achieved assuming the empirically calibrated Meurer et al. (1999) relation. Implicit in this relation is the assumption of an intrinsic UV continuum slope ($\\beta=-2.23$). However, results from numerical simulations suggest that the intrinsic UV continuum slopes of high-redshift star forming galaxies are bluer than this, and moreover vary with redshift. Using values of the intrinsic slope predicted by numerical models of galaxy formation combined with a Calzetti et al. (2000) reddening law we infer UV attenuations ($A_{1500}$) $0.35-0.5\\,{\\rm mag}$ ($A_{V}$: $0.14-0.2\\,{\\rm mag}$ assuming Calzetti et al. 2000) greater than simply assuming the Meurer relation. This...

  15. The Luminosity Function of the Host Galaxies of QSOs and BL Lac Objects

    CERN Document Server

    Carangelo, N; Treves, A

    2001-01-01

    A clear insight of the galaxies hosting active galactic nuclei is of fundamental importance for understanding the processes of galaxies and nuclei formation and their cosmic evolution. A good characterization of the host galaxies properties requires images of excellent quality in order to disentangle the light of the galaxy from that of the bright nucleus. To this aim HST has provided a major improvement of data on QSOs (Disney et al. 1995; Bahcall et al. 1996, 1997; Boyce et al. 1998; McLure et al. 1999; Hamilton et al. 2000; Kukula et al. 2001) and BL Lacs (Scarpa et al. 2000, Urry et al. 2000). We present a comparative study of low redshift QSO and BL Lac host galaxy luminosity function (HGLF). To this aim we have considered samples of BL Lacs (Urry et al. 2000) and QSOs (Bahcall et al. 1997; Boyce et al. 1998; McLure et al. 1999) that have been well resolved by images obtained with WFPC2 on board of HST.

  16. The metallicity-luminosity relation at medium redshift based on faint CADIS emission line galaxies

    CERN Document Server

    Maier, C; Hippelein, H

    2004-01-01

    The emission line survey within the Calar Alto Deep Imaging Survey (CADIS) detects galaxies with very low continuum brightness by using an imaging Fabry-Perot interferometer. With spectroscopic follow-up observations of MB>~-19 CADIS galaxies using FORS2 at the VLT and DOLORES at TNG we obtained oxygen abundances of 5 galaxies at z~0.4 and 10 galaxies at z~0.64. Combining these measurements with published oxygen abundances of galaxies with MB<~-19 we find evidence that a metallicity-luminosity relation exists at medium redshift, but it is displaced to lower abundances and higher luminosities compared to the metallicity-luminosity relation in the local universe. Comparing the observed metallicities and luminosities of galaxies at z<3 with Pegase2 chemical evolution models we have found a favoured scenario in which the metallicity of galaxies increases by a factor of ~2 between z~0.7 and today, and their luminosity decreases by ~0.5-0.9mag.

  17. Feedback and the Structure of Simulated Galaxies at redshift z=2

    CERN Document Server

    Sales, Laura V; Schaye, Joop; Vecchia, Claudio Dalla; Springel, Volker; Booth, C M

    2010-01-01

    We study the properties of simulated high-redshift galaxies using cosmological N-body/gasdynamical runs from the OverWhelmingly Large Simulations (OWLS) project. The runs contrast several feedback implementations of varying effectiveness: from no-feedback, to supernova-driven winds to powerful AGN-driven outflows. These different feedback models result in large variations in the abundance and structural properties of bright galaxies at z=2. We find that feedback affects the baryonic mass of a galaxy much more severely than its spin, which is on average roughly half that of its surrounding dark matter halo in our runs. Feedback induces strong correlations between angular momentum content and galaxy mass that leave their imprint on galaxy scaling relations and morphologies. Encouragingly, we find that galaxy disks are common in moderate-feedback runs, making up typically ~50% of all galaxies at the centers of haloes with virial mass exceeding 1e11 M_sun. The size, stellar masses, and circular speeds of simulate...

  18. Galaxy Zoo Hubble: First results of the redshift evolution of disk fraction in the red sequence

    Science.gov (United States)

    Galloway, Melanie; Willett, Kyle; Fortson, Lucy; Scarlata, Claudia; Beck, Melanie; Masters, Karen; Melvin, Tom

    2016-01-01

    The transition of galaxies from the blue cloud to the red sequence is commonly linked to a morphological transformation from disk to elliptical structure. However, the correlation between color and morphology is not one-to-one, as evidenced by the existence of a significant population of red disks. As this stage in a galaxy's evolution is likely to be transitory, the mechanism by which red disks are formed offers insight to the processes that trigger quenching of star formation and the galaxy's position on the star-forming sequence. To study the population of disk galaxies in the red sequence as a function of cosmic time, we utilize data from the Galaxy Zoo: Hubble project, which uses crowdsourced visual classifications of images of galaxies selected from the AEGIS, COSMOS, GEMS, and GOODS surveys. We construct a large sample of over 10,000 disk galaxies spanning a wide (0 < z < 1.0) redshift range. We use this sample to examine the change in the fraction of disks in the red sequence with respect to all disks from z˜1 to the present day. Preliminary results confirm that the fraction of disks in the red sequence decreases as the Universe evolves. We discuss the quenching processes which may explain this trend, and which morphological transformations are most affected by it.

  19. Luminosities, Masses and Star Formation Rates of Galaxies at High Redshift (IAU279 conference proceedings)

    CERN Document Server

    Bunker, Andrew

    2013-01-01

    There has been great progress in recent years in discovering star forming galaxies at high redshifts (z>5), close to the epoch of reionization of the intergalactic medium (IGM). The WFC3 and ACS cameras on the Hubble Space Telescope have enabled Lyman break galaxies to be robustly identified, but the UV luminosity function and star formation rate density of this population at z=6-8 seems to be much lower than at z=2-4. High escape fractions and a large contribution from faint galaxies below our current detection limits would be required for star-forming galaxies to reionize the Universe. We have also found that these galaxies have blue rest-frame UV colours, which might indicate lower dust extinction at z>5. There has been some spectroscopic confirmation of these Lyman break galaxies through Lyman-alpha emission, but the fraction of galaxies where we see this line drops at z>7, perhaps due to the onset of the Gunn-Peterson effect (where the IGM is opaque to Lyman-alpha).

  20. The Red Sequence of High-Redshift Clusters: a Comparison with Cosmological Galaxy Formation Models

    CERN Document Server

    Menci, N; Gobat, R; Strazzullo, V; Rettura, A; Mei, S; Demarco, R

    2008-01-01

    We compare the results from a semi-analytic model of galaxy formation with spectro-photometric observations of distant galaxy clusters observed in the range 0.8< z< 1.3. We investigate the properties of their red sequence (RS) galaxies and compare them with those of the field at the same redshift. In our model we find that i) a well-defined, narrow RS is obtained already by z= 1.2; this is found to be more populated than the field RS, analogously to what observed and predicted at z=0; ii) the predicted U-V rest-frame colors and scatter of the cluster RS at z=1.2 have average values of 1 and 0.15 respectively, with a cluster-to-cluster variance of 0.2 and 0.06, respectively. The scatter of the RS of cluster galaxies is around 5 times smaller than the corresponding field value; iii) when the RS galaxies are considered, the mass growth histories of field and cluster galaxies at z=1.2 are similar, with 90 % of the stellar mass of RS galaxies at z=1.2 already formed at cosmic times t=2.5 Gyr, and 50 % at t=1...

  1. Nuclear to host galaxy relation of high redshift quasars

    Directory of Open Access Journals (Sweden)

    J. K. Kotilainen

    2008-01-01

    Full Text Available Se presentan imágenes en el cercano infrarrojo de cuásares a 1 < z < 2 con una cobertura amplia (~ 4 mag de la función de luminosidad de cuásares. Las galaxias anfitrionas de cuásares radio-fuertes (RLQ y radio-callados (RQQ tienen luminosidades en el intervalo de las elípticas masivas inactivas entre L* y 10 L*. Las galaxias huésped de los RLQ son más luminosas que las de los RQQ. La brecha en luminosidad es independiente de la luminosidad en la banda-U en reposo pero está correlacionada con la luminosidad en la banda-R en reposo. Esta diferencia en el color de RLQ y RQQ es probablemente debida a una combinación de la diferencia intrínseca en sus SEDs y a un efecto de selección debido a la extinción interna por polvo. Hay una correlación razonable entre las luminosidades nuclear y huésped para RLQ pero no para RQQ. Si la banda-R traza la luminosidad bolométrica y si la luminosidad huésped es proporcional a la masa del agujero negro, los cuásares de alto corrimiento al rojo emiten en un estrecho intervalo de potencias con respecto a su luminosidad de Eddington.

  2. Photometric Redshifts and Systematic Variations in the SEDs of Luminous Red Galaxies from the SDSS DR7

    CERN Document Server

    Greisel, Natascha; Drory, Niv; Bender, Ralf; Saglia, Roberto; Snigula, Jan

    2013-01-01

    We describe the construction of a template set of spectral energy distributions (SEDs) for the estimation of photometric redshifts of luminous red galaxies (LRGs) with a Bayesian template fitting method. By examining the color properties of several publicly available SED sets within a redshift range of 00.15) of 0.12%. We show that templates that optimally describe the brightest galaxies (-24.5galaxies at z<0.1 strongly differ as a function of the absolute magnitude of the galaxies, indicating an increase in star formation activity for less luminous galaxies. Our findings based on the photometry of the SDSS LRGs and our SED template fitting are supported by comparison to the average SDSS LRG spectra in different luminosity and redshift bins.

  3. The Quest for Dusty Star-forming Galaxies at High Redshift z ≳ 4

    Science.gov (United States)

    Mancuso, C.; Lapi, A.; Shi, J.; Gonzalez-Nuevo, J.; Aversa, R.; Danese, L.

    2016-06-01

    We exploit the continuity equation approach and “main-sequence” star formation timescales to show that the observed high abundance of galaxies with stellar masses ≳ a few 1010 M ⊙ at redshift z ≳ 4 implies the existence of a galaxy population featuring large star formation rates (SFRs) ψ ≳ 102 M ⊙ yr-1 in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z ≲ 3 in the far-IR band by the Herschel Space Observatory. We work out specific predictions for the evolution of the corresponding stellar mass and SFR functions out to z ˜ 10, determining that the number density at z ≲ 8 for SFRs ψ ≳ 30 M ⊙ yr-1 cannot be estimated relying on the UV luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from the AzTEC-LABOCA, SCUBA-2, and ALMA-SPT surveys are already addressing it. We demonstrate how an observational strategy based on color preselection in the far-IR or (sub-)millimeter band with Herschel and SCUBA-2, supplemented by photometric data from on-source observations with ALMA, can allow us to reconstruct the bright end of the SFR functions out to z ≲ 8. In parallel, such a challenging task can be managed by exploiting current UV surveys in combination with (sub-)millimeter observations by ALMA and NIKA2 and/or radio observations by SKA and its precursors.

  4. Galaxy Zoo: evidence for rapid, recent quenching within a population of AGN host galaxies

    Science.gov (United States)

    Smethurst, R. J.; Lintott, C. J.; Simmons, B. D.; Schawinski, K.; Bamford, S. P.; Cardamone, C. N.; Kruk, S. J.; Masters, K. L.; Urry, C. M.; Willett, K. W.; Wong, O. I.

    2016-12-01

    We present a population study of the star formation history of 1244 Type 2 active galactic nuclei (AGN) host galaxies, compared to 6107 inactive galaxies. A Bayesian method is used to determine individual galaxy star formation histories, which are then collated to visualize the distribution for quenching and quenched galaxies within each population. We find evidence for some of the Type 2 AGN host galaxies having undergone a rapid drop in their star formation rate within the last 2 Gyr. AGN feedback is therefore important at least for this population of galaxies. This result is not seen for the quenching and quenched inactive galaxies whose star formation histories are dominated by the effects of downsizing at earlier epochs, a secondary effect for the AGN host galaxies. We show that histories of rapid quenching cannot account fully for the quenching of all the star formation in a galaxy's lifetime across the population of quenched AGN host galaxies, and that histories of slower quenching, attributed to secular (non-violent) evolution, are also key in their evolution. This is in agreement with recent results showing that both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes. The availability of gas in the reservoirs of a galaxy, and its ability to be replenished, appear to be the key drivers behind this co-evolution.

  5. Galaxy Transformation Under Extreme Conditions: The Evolution of Galaxies in the Largest Structures in the High Redshift Universe

    Science.gov (United States)

    Lemaux, Brian Clark

    This dissertation describes research performed in the field of observational astrophysics as part of the Observations of Redshift Evolution in Large Scale Environment (ORELSE) survey. The general motivation of the research presented in this dissertation is to investigate the processes responsible for the evolution of galaxies in a wide range of physical conditions over cosmic time. Throughout this dissertation, galaxy populations will be considered in the very nearby universe (i.e., within one billion light years from Earth), the middle-aged universe (i.e., eight billion years ago), and in the very early universe (i.e., just one billion years after the beginning of the universe). In each chapter I present unique data from observations taken and analyzed specifically for the ORELSE survey. In the first part of this dissertation I describe the context, aims, and current state of the ORELSE survey. The studies presented in this dissertation span a large range of galaxy samples and investigate a variety of different astrophysical phenomena. As all of these studies fall under the context of galaxy evolution, these initial sections will set the framework for the variety of studies presented in this thesis. In the second part of this dissertation I present four studies undertaken to investigate various aspects of galaxy evolution. The first of these studies is an investigation of a large population of very distant galaxies detected in one of the ORELSE fields. The survey in this field represents the deepest survey of a particular kind of very distant galaxy population known as Lymanalpha Emitter (LAEs). The number of LAEs found in this survey far exceeded expectations for such galaxies and are shown to be in excess of every other survey of similar galaxies at similar distances. This result has important consequences for galaxy evolution studies, as it suggests that faint LAEs may be much more numerous than previously thought. This work also has important consequences for

  6. Spectroscopy of supernova host galaxies from the SDSS-II SN survey with the SDSS and BOSS spectrographs

    Science.gov (United States)

    Olmstead, Matthew Dwaune

    Type Ia supernovae (SNeIa) have been used as standard candles to measure cosmological distances. The initial discovery of the accelerated expansion of the universe was performed using ~50 SNe Ia. Large SNe surveys have increased the number of spectroscopically-confirmed SNe Ia to over a thousand with redshift coverage beyond z = 1. We are now in the age of abundant photometry without the ability for full follow-up spectroscopy of all SN candidates. SN cosmology using these large samples will increasingly rely on robust photometric classification of SN candidates. Photometric classification will increase the sample by including faint SNe as these are preferentially not observed with follow-up spectroscopy. The primary concern with using photometrically classified SNe Ia in cosmology is when a core-collapse SNe is incorrectly classified as an SN Ia. This can be mitigated by obtaining the host galaxy redshift of each SN candidate and using this information as a prior in the photometric classification, removing one degree of freedom. To test the impact of redshift on photometric classification, I have performed an assessment on photometric classification of candidates from the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. I have tested the classification with and without redshift priors by looking at the change of photometric classification, the effect of data quality on photometric classification, and the effect of SN light curve properties on photometric classification. Following our suggested classification scheme, there are a total of 1038 photometrically classified SNe Ia when using a flat redshift prior and 1002 SNe~Ia with the spectroscopic redshift. For 912 (91.0%) candidates classified as likely SNe Ia without redshift information, the classification is unchanged when adding the host galaxy redshift. Finally, I investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. When using the SALT2

  7. Constraining galaxy cluster temperatures and redshifts with eROSITA survey data

    Science.gov (United States)

    Borm, K.; Reiprich, T. H.; Mohammed, I.; Lovisari, L.

    2014-07-01

    Context. The nature of dark energy is imprinted in the large-scale structure of the Universe and thus in the mass and redshift distribution of galaxy clusters. The upcoming eROSITA instrument will exploit this method of probing dark energy by detecting ~100 000 clusters of galaxies in X-rays. Aims: For a precise cosmological analysis the various galaxy cluster properties need to be measured with high precision and accuracy. To predict these characteristics of eROSITA galaxy clusters and to optimise optical follow-up observations, we estimate the precision and the accuracy with which eROSITA will be able to determine galaxy cluster temperatures and redshifts from X-ray spectra. Additionally, we present the total number of clusters for which these two properties will be available from the eROSITA survey directly. Methods: We simulate the spectra of galaxy clusters for a variety of different cluster masses and redshifts while taking into account the X-ray background as well as the instrumental response. An emission model is then fit to these spectra to recover the cluster temperature and redshift. The number of clusters with precise properties is then based on the convolution of the above fit results with the galaxy cluster mass function and an assumed eROSITA selection function. Results: During its four years of all-sky surveys, eROSITA will determine cluster temperatures with relative uncertainties of ΔT/T ≲ 10% at the 68%-confidence level for clusters up to redshifts of z ~ 0.16 which corresponds to ~1670 new clusters with precise properties. Redshift information itself will become available with a precision of Δz/ (1 + z) ≲ 10% for clusters up to z ~ 0.45. Additionally, we estimate how the number of clusters with precise properties increases with a deepening of the exposure. For the above clusters, the fraction of catastrophic failures in the fit is below 20% and in most cases it is even much smaller. Furthermore, the biases in the best-fit temperatures as

  8. An HST study of three very faint GRB host galaxies

    DEFF Research Database (Denmark)

    Jaunsen, A.O.; Andersen, M.I.; Hjorth, J.;

    2003-01-01

    . (2002). We obtain a revised and much higher probability that the galaxies identified as hosts indeed are related to the GRBs (P(n(chance))=0.69, following Bloom et al. 2002), thereby strengthening the conclusion that GRBs are preferentially located in star-forming regions in their hosts. Apart from......As part of the HST/STIS GRB host survey program we present the detection of three faint gamma-ray burst (GRB) host galaxies based on an accurate localisation using ground-based data of the optical afterglows (OAs). A common property of these three hosts is their extreme faintness. The location...... at which GRBs occur with respect to their host galaxies and surrounding environments are robust indicators of the nature of GRB progenitors. The bursts studied here are among the four most extreme outliers, in terms of relative distance from the host center, in the recent comprehensive study of Bloom et al...

  9. GASDRA: Galaxy Spectrum Dynamic Range Analysis for Photometric Redshift Filter Partition Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Vicente, J. de; Sanchez, E.; Sevilla, I.; Castilla, J.; Ponce, R.; Sanchez, F. J.

    2012-04-11

    The photometric redshift is an active area of research. It is becoming the preferred method for redshift measurement above spectroscopy one for large surveys. In these surveys, the requirement in redshift precision is relaxed in benefit of obtaining the measurements of large number of galaxies. One of the more relevant decisions to be taken in the design of a photometric redshift experiment is the number of filters since it affects deeply to the precision and survey time. Currently, there is not a clear method for evaluating the impact in both precision and exposure time of a determined filter partition set and usually it is determined by detailed simulations on the behavior of photo-z algorithms. In this note we describe GASDRA, a new method for extracting the minimal signal to noise requirement, depending on the number of filters needed for preserving the filtered spectrum shape, and hence to make feasible the spectrum identification. The application of this requirement guaranties a determined precision in the spectrum measurement. Although it cannot be translated directly to absolute photometric redshift error, it does provide a method for comparing the relative precision achieved in the spectrum representation by different sets of filters. We foresee that this relative precision is close related to photo-z error. In addition, we can evaluate the impact in the exposure time of any filter partition set with respect to other. (Author) 11 refs.

  10. A Comparison of Six Photometric Redshift Methods Applied to 1.5 Million Luminous Red Galaxies

    CERN Document Server

    Abdalla, Filipe B; Lahav, Ofer; Rashkov, Valery

    2008-01-01

    We present an updated version of MegaZ-LRG (Collister et al.,(2007)) with photometric redshifts derived with the neural network method, ANNz as well as five other publicly available photo-z codes (HyperZ, SDSS, Le PHARE, BPZ and ZEBRA) for ~1.5 million Luminous Red Galaxies (LRGs) in SDSS DR6. This allows us to identify how reliable codes are relative to each other if used as described in their public release. We compare and contrast the relative merits of each code using ~13000 spectroscopic redshifts from the 2SLAQ sample. We find that the performance of each code depends on the figure of merit used to assess it. As expected, the availability of a complete training set means that the training method performs best in the intermediate redshift bins where there are plenty of training objects. Codes such as Le PHARE, which use new observed templates perform best in the lower redshift bins. All codes produce reasonable photometric redshifts, the 1-sigma scatters ranging from 0.057 to 0.097 if averaged over the e...

  11. AGN host galaxy mass function in COSMOS: is AGN feedback responsible for the mass-quenching of galaxies?

    CERN Document Server

    Bongiorno, A; Merloni, A; Zamorani, G; Ilbert, O; La Franca, F; Peng, Y; Piconcelli, E; Mainieri, V; Silverman, J D; Brusa, M; Fiore, F; Salvato, M; Scoville, N

    2016-01-01

    We investigate the role of supermassive black holes in the global context of galaxy evolution by measuring the host galaxy stellar mass function (HGMF) and the specific accretion rate i.e., lambda_SAR, distribution function (SARDF) up to z~2.5 with ~1000 X-ray selected AGN from XMM-COSMOS. Using a maximum likelihood approach, we jointly fit the stellar mass function and specific accretion rate distribution function, with the X-ray luminosity function as an additional constraint. Our best fit model characterizes the SARDF as a double power-law with mass dependent but redshift independent break whose low lambda_SAR slope flattens with increasing redshift while the normalization increases. This implies that, for a given stellar mass, higher lambda_SAR objects have a peak in their space density at earlier epoch compared to the lower lambda_SAR ones, following and mimicking the well known AGN cosmic downsizing as observed in the AGN luminosity function. The mass function of active galaxies is described by a Schech...

  12. Bright [CII] and dust emission in three z>6.6 quasar host galaxies observed by ALMA

    CERN Document Server

    Venemans, B P; Zschaechner, L; Decarli, R; De Rosa, G; Findlay, J R; McMahon, R G; Sutherland, W J

    2015-01-01

    We present ALMA detections of the [CII] 158 micron emission line and the underlying far-infrared continuum of three quasars at 6.6~6 quasar hosts correlate with the quasar's bolometric luminosity. In one quasar, the [CII] line is significantly redshifted by ~1700 km/s with respect to the MgII broad emission line. Comparing to values in the literature, we find that, on average, the MgII is blueshifted by 480 km/s (with a standard deviation of 630 km/s) with respect to the host galaxy redshift, i.e. one of our quasars is an extreme outlier. Through modeling we can rule out a flat rotation curve for our brightest [CII] emitter. Finally, we find that the ratio of black hole mass to host galaxy (dynamical) mass is higher by a factor 3-4 (with significant scatter) than local relations.

  13. The host galaxies of active galactic nuclei with powerful relativistic jets

    CERN Document Server

    Olguín-Iglesias, A; Kotilainen, J K; Chavushyan, V; Tornikoski, M; Valtaoja, E; Añorve, C; Valdes, J; Carrasco, L

    2016-01-01

    We present deep Near-infrared (NIR) images of a sample of 19 intermediate-redshift ($0.310^{27}$ WHz$^{-1}$), previously classified as flat-spectrum radio quasars. We also compile host galaxy and nuclear magnitudes for blazars from literature. The combined sample (this work and compilation) contains 100 radio-loud AGN with host galaxy detections and a broad range of radio luminosities $L_{1.4GHz} \\sim 10^{23.7} - 10^{28.3}$~WHz$^{-1}$, allowing us to divide our sample into high-luminosity blazars (HLBs) and low-luminosity blazars (LLBs). The host galaxies of our sample are bright and seem to follow the $\\mu_{e}$-$R_{eff}$ relation for ellipticals and bulges. The two populations of blazars show different behaviours in the \\mnuc - \\mbulge plane, where a statistically significant correlation is observed for HLBs. Although it may be affected by selection effects, this correlation suggests a close coupling between the accretion mode of the central supermassive black hole and its host galaxy, that could be interpre...

  14. The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshifts

    CERN Document Server

    Mandelbaum, Rachel; Bridle, Sarah; Abdalla, Filipe B; Brough, Sarah; Colless, Matthew; Couch, Warrick; Croom, Scott; Davis, Tamara; Drinkwater, Michael J; Forster, Karl; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, Tornado; Madore, Barry; Martin, Chris; Pimbblet, Kevin; Poole, Gregory B; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted

    2009-01-01

    Correlations between the intrinsic shapes of galaxy pairs, and between the intrinsic shapes of galaxies and the large-scale density field, may be induced by tidal fields. These correlations, which have been detected at low redshifts (z<0.35) for bright red galaxies in the Sloan Digital Sky Survey (SDSS), and for which upper limits exist for blue galaxies at z~0.1, provide a window into galaxy formation and evolution, and are also an important contaminant for current and future weak lensing surveys. Measurements of these alignments at intermediate redshifts (z~0.6) that are more relevant for cosmic shear observations are very important for understanding the origin and redshift evolution of these alignments, and for minimising their impact on weak lensing measurements. We present the first such intermediate-redshift measurement for blue galaxies, using galaxy shape measurements from SDSS and spectroscopic redshifts from the WiggleZ Dark Energy Survey. Our null detection allows us to place upper limits on the...

  15. Thermal and radiative AGN feedback have a limited impact on star formation in high-redshift galaxies

    CERN Document Server

    Roos, Orianne; Bournaud, Frédéric; Gabor, Jared M

    2014-01-01

    Active Galactic Nuclei (AGNs) are good candidates to explain star formation quenching, depending on the coupling between the energy they re-inject in the galaxy and the interstellar medium. The purpose of this study is to model and quantify the impact of AGN long-range ionizing radiation -- on top of the often considered small-scale energy deposition -- on the physical state of the gas of the host-galaxy, and therefore on its ability to form stars. We formulated an AGN Spectral Energy Distribution, which we used with the radiative transfer code Cloudy to compute ionization in a simulated high-redshift disk-galaxy. This simulation has a high resolution ($\\sim$ 6 pc) and includes standard thermal AGN feedback, and we calculate the radiative transfer in post-processing. Surprisingly, while these models give birth to significant AGN-driven outflows, we find that the reduction in Star Formation Rate due to ionization radiation and thermal heating is of a few percents at most for a quasar luminosity ($L_{bol}=10^{4...

  16. Unveiling the Important Role of Groups in the Evolution of Massive Galaxies: Insights from an Infrared Passive Sequence at Intermediate Redshift

    CERN Document Server

    Wilman, D J; Tyler, K; McGee, S L; Oemler, A; Morris, S L; Balogh, M L; Bower, R G; Mulchaey, J S

    2008-01-01

    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 haloes which host most of these galaxies. A stellar mass selected M_* >~ 2x10^10M_sol sample at z~0.4 is constructed within the CNOC2 redshift survey. A sensitive Mid InfraRed (MIR) IRAC colour is used to isolate passive galaxies. It produces a bimodal distribution, in which passive galaxies (highlighted by morphological early-types) define a tight MIR colour 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 8microns (InfraRed-Excess or IRE galaxies). They include all known morphological late-types. Comparison with EW[OII] shows that MIR colour is highly sensitive to low levels of activity, and allows us to separate dusty-active from passive galaxies. The fraction of IRE galaxies, f(IRE) drops...

  17. A far-infrared spectroscopic survey of intermediate redshift (ultra) luminous infrared galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Magdis, Georgios E.; Rigopoulou, D. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Hopwood, R.;