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9 results on '"Civano F."'

1. The VLA‐COSMOS 3 GHz Large Project: The infrared‐radio correlation of star‐ forming galaxies and AGN to z less than or similar to 6

Author

Delhaize, J., Smolcic, V., Delvecchio, I., Novak, M., Sargent, M., Baran, N., Magnelli, B., Zamorani, G., Schinnerer, E., Murphy, E. J., Aravena, M., Berta, S., Bondi, M., Capak, P., Carilli, C., Ciliegi, P., Civano, F., Ilbert, O., Karim, A., Laigle, C., Le Fevre, O., Marchesi, S., McCracken, H. J., Salvato, M., Seymour, N., Tasca, L., Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

International audience; We examine the behaviour of the infrared‐radio correlation (IRRC) over the range 0 < z less than or similar to 6 using new, highly sensitive 3 GHz observations with the Karl G. Jansky Very Large Array (VLA) and infrared data from the Herschel Space Observatory in the 2 deg(2) COSMOS field. We distinguish between objects where emission is believed to arise solely from star‐formation, and those where an active galactic nucleus (AGN) is thought to be present. We account for non‐detections in the radio or in the infrared using a doublycensored survival analysis. We find that the IRRC of star‐forming galaxies, quantified by the infrared‐to‐1.4 GHz radio luminosity ratio (qTIR), decreases with increasing redshift: q(TIR)(z) = (2.88 +/‐ 0.03)(1 + z)(‐0.19 +/‐ 0.01). This is consistent with several previous results from the literature. Moderate‐to‐high radiative luminosity AGN do not follow the same q(TIR)(z) trend as star‐forming galaxies, having a lower normalisation and steeper decrease with redshift. We cannot rule out the possibility that unidentified AGN contributions only to the radio regime may be steepening the observed q(TIR)(z) trend of the star‐forming galaxy population. We demonstrate that the choice of the average radio spectral index directly affects the normalisation, as well as the derived trend with redshift of the IRRC. An increasing fractional contribution to the observed 3 GHz flux by free‐free emission of star‐forming galaxies may also affect the derived evolution. However, we find that the standard (M82‐based) assumption of the typical radio spectral energy distribution (SED) for star‐forming galaxies is inconsistent with our results. This suggests a more complex shape of the typical radio SED for star‐forming galaxies, and that imperfect K corrections in the radio may govern the derived trend of decreasing q(TIR) with increasing redshift. A more detailed understanding of the radio spectrum is therefore required for robust K corrections in the radio and to fully understand the cosmic evolution of the IRRC. Lastly, we present a redshift‐dependent relation between rest‐frame 1.4 GHz radio luminosity and star formation rate taking the derived redshift trend into account.

Published
2017
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2. The VLA‐COSMOS 3 GHz Large Project: AGN and host‐galaxy properties out to z less than or similar to 6

Author

Delvecchio, I., Smolcic, V., Zamorani, G., Lagos, C. Del P., Berta, S., Delhaize, J., Baran, N., Alexander, D. M., Rosario, D. J., Gonzalez‐Perez, V., Ilbert, O., Lacey, C. G., Le Fevre, O., Miettinen, O., Aravena, M., Bondi, M., Carilli, C., Ciliegi, P., Mooley, K., Novak, M., Schinnerer, E., Capak, P., Civano, F., Fanidakis, N., Ruiz, N. Herrera, Karim, A., Laigle, C., Marchesi, S., McCracken, H. J., Middleberg, E., Salvato, M., Tasca, L., Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

International audience; We explore the multiwavelength properties of AGN host galaxies for different classes of radio‐selected AGN out to z less than or similar to 6 via a multiwavelength analysis of about 7700 radio sources in the COSMOS field. The sources were selected with the Very Large Array (VLA) at 3 GHz (10 cm) within the VLA‐COSMOS 3 GHz Large Project, and cross‐matched with multiwavelength ancillary data. This is the largest sample of high‐redshift (z less than or similar to 6) radio sources with exquisite photometric coverage and redshift measurements available. We constructed a sample of moderate‐to‐high radiative luminosity AGN (HLAGN) via spectral energy distribution decomposition combined with standard X‐ray and mid‐infrared diagnostics. Within the remainder of the sample we further identified low‐to‐moderate radiative luminosity AGN (MLAGN) via excess in radio emission relative to the star formation rates in their host galaxies. We show that at each redshift our HLAGN have systematically higher radiative luminosities than MLAGN and that their AGN power occurs predominantly in radiative form, while MLAGN display a substantial mechanical AGN luminosity component. We found significant differences in the host properties of the two AGN classes, as a function of redshift. At z < 1 : 5, MLAGN appear to reside in significantly more massive and less star‐forming galaxies compared to HLAGN. At z > 1., we observed a reversal in the behaviour of the stellar mass distributions with the HLAGN populating the higher stellar mass tail. We interpret this finding as a possible hint of the downsizing of galaxies hosting HLAGN, with the most massive galaxies triggering AGN activity earlier than less massive galaxies, and then fading to MLAGN at lower redshifts. Our conclusion is that HLAGN and MLAGN samples trace two distinct galaxy and AGN populations in a wide range of redshifts, possibly resembling the radio AGN types often referred to as radiative‐and jet‐mode (or high‐and low‐excitation), respectively, whose properties might depend on the different availability of cold gas supplies.

Published
2017
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3. The VLA‐COSMOS 3 GHz Large Project: Cosmic star formation history since z similar to 5

Author

Novak, M., Smolcic, V., Delhaize, J., Delvecchio, I., Zamorani, G., Baran, N., Bondi, M., Capak, P., Carilli, C. L., Ciliegi, P., Civano, F., Ilbert, O., Karim, A., Laigle, C., Le Fevre, O., Marchesi, S., Mccracken, H., Miettinen, O., Salvato, M., Sargent, M., Schinnerer, E., Tasca, L., Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

International audience; We make use of the deep Karl G. Jansky Very Large Array (VLA) COSMOS radio observations at 3 GHz to infer radio luminosity functions of star‐forming galaxies up to redshifts of z similar to 5 based on approximately 6000 detections with reliable optical counterparts. This is currently the largest radio‐selected sample available out to z similar to 5 across an area of 2 square degrees with a sensitivity of rms approximate to 2.3 mu Jy beam(‐1). By fixing the faint and bright end shape of the radio luminosity function to the local values, we find a strong redshift trend that can be fitted with a pure luminosity evolution L‐1.4 (GHz) proportional to /(1 + z)((3.16 +/‐ 0.2)‐(0.32 +/‐ 0.07)z). We estimate star formation rates (SFRs) from our radio luminosities using an infrared (IR)‐radio correlation that is redshift dependent. By integrating the parametric fits of the evolved luminosity function we calculate the cosmic SFR density (SFRD) history since z similar to 5. Our data suggest that the SFRD history peaks between 2 < z < 3 and that the ultraluminous infrared galaxies (100 M‐circle dot yr(‐1) < SFR < 1000 M‐circle dot yr(‐1)) contribute up to similar to 25% to the total SFRD in the same redshift range. Hyperluminous infrared galaxies (SFR > 1000 M fi yr 1) contribute an additional less than or similar to 2% in the entire observed redshift range. We find evidence of a potential underestimation of SFRD based on ultraviolet (UV) rest‐frame observations of Lyman break galaxies at high redshifts (z greater than or similar to 4) on the order of 15‐20%, owing to appreciable star formation in highly dust‐obscured galaxies, which might remain undetected in such UV observations.

Published
2017
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4. Physical properties of z \textgreater 4 submillimeter galaxies in the COSMOS field

Author

Smolcic, V., Karim, A., Miettinen, O., Novak, M., Magnelli, B., Riechers, D. A., Schinnerer, E., Capak, P., Bondi, M., Ciliegi, P., Aravena, M., Bertoldi, F., Bourke, S., Banfield, J., Carilli, C. L., Civano, F., Ilbert, O., Intema, H. T., Le Fevre, O., Finoguenov, A., Hallinan, G., Kloeckner, H. -R., Koekemoer, A., Laigle, C., Masters, D., Mccracken, H. J., Mooley, K., Murphy, E., Navarette, F., Salvato, M., Sargent, M., Sheth, K., Toft, S., Zamorani, G., Argelander Institute for Astronomy (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Extraterrestrische Physik (MPE), AUTRES, Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), Max-Planck-Institut für Radioastronomie (MPIFR), National Radio Astronomy Observatory [Socorro] (NRAO), National Radio Astronomy Observatory (NRAO), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Space Telescope Science Institute (STSci), Centre de résonance magnétique biologique et médicale (CRMBM), Aix Marseille Université (AMU)-Assistance Publique - Hôpitaux de Marseille (APHM)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Excellence Cluster Universe, excellence cluster centre, Astronomy Centre, University of Sussex, Spitzer Science Center, California Institute of Technology, Pasadena, Dark Cosmology Centre (DARK), Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], and University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; We investigate the physical properties of a sample of six submillimeter galaxies (SMGs) in the COSMOS field, spectroscopically confirmed to lie at redshifts z \textgreater 4. While the redshifts for four of these SMGs were previously known, we present here two newly discovered z(spec) \textgreater 4 SMGs. For our analysis we employ the rich (X-ray to radio) COSMOS multi-wavelength datasets. In particular, we use new data from the Giant Meterwave Radio Telescope (GMRT) 325 MHz and 3 GHz Jansky Very Large Array (VLA) to probe the rest-frame 1.4 GHz emission at z = 4, and to estimate the sizes of the star formation regions of these sources, respectively. We find that only one SMG is clearly resolved at a resolution of 0.” 6 x 0.” 7 at 3 GHz, two may be marginally resolved, while the remaining three SMGs are unresolved at this resolution. Combining this with sizes from high-resolution (sub-) mm observations available in the literature for AzTEC 1 and AzTEC 3 we infer a median radio-emitting size for our z \textgreater 4 SMGs of (0.” 63 +/- 0.” 12) x (0.” 35 +/- 0.” 05) or 4.1 x 2.3 kpc(2) (major x minor axis; assuming z = 4.5) or lower if we take the two marginally resolved SMGs as unresolved. This is consistent with the sizes of star formation regions in lower-redshift SMGs, and local normal galaxies, yet higher than the sizes of star formation regions of local ultraluminous infrared galaxies (ULIRGs). Our SMG sample consists of a fair mix of compact and more clumpy systems with multiple, perhaps merging, components. With an average formation time of similar to 280 Myr, as derived through modeling of the UV IR spectral energy distributions, the studied SMGs are young systems. The average stellar mass, dust temperature, and IR luminosity we derive are M-star similar to 1.4 x 10(11) M-circle dot, T-dust similar to 43 K, and L-IR similar to 1.3 x 10(13) L-circle dot, respectively. The average L-IR is up to an order of magnitude higher than for SMGs at lower redshifts. Our SMGs follow the correlation between dust temperature and IR luminosity as derived for Herschel-selected 0.1 \textless z \textless 2 galaxies. We study the IR-radio correlation for our sources and find a deviation from that derived for z \textless 3 ULIRGs (\textless q(IR)\textgreater = 1.95 +/- 0.26 for our sample, compared to q approximate to 2.6 for IR luminous galaxies at z \textless 2). In summary, we find that the physical properties derived for our z \textgreater 4 SMGs put them at the high end of the L-IR-T-dust distribution of SMGs, and that our SMGs form a morphologically heterogeneous sample. Thus, additional in-depth analyses of large, statistical samples of high-redshift SMGs are needed to fully understand their role in galaxy formation and evolution.

Published
2015
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5. Bolometric luminosities and Eddington ratios of X-ray selected active galactic nuclei in the XMM -COSMOS survey

Author

Lusso, E., Comastri, A., Simmons, B. D., Mignoli, M., Zamorani, G., Vignali, C., Brusa, M., Shankar, F., Lutz, D., Trump, J. R., Maiolino, R., Gilli, R., Bolzonella, M., Puccetti, S., Salvato, M., Impey, C. D., Civano, F., Elvis, M., Mainieri, V., Silverman, J. D., Koekemoer, A. M., Bongiorno, A., Merloni, A., Berta, S., Floc'h, E. Le, Magnelli, B., Pozzi, F., Riguccini, L., INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), AUTRES, INAF - Osservatorio Astronomico di Capodimonte (OAC), Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Extraterrestrische Physik (MPE), INAF - Osservatorio Astronomico di Bologna (OABO), Università di Bologna, Dipartimento di Astronomia, Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Space Telescope Science Institute (STSci), Max-Planck-Institut für Astrophysik (MPA), Ecosystèmes lagunaires : organisation biologique et fonctionnement (ECOLAG), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Lusso E., Comastri A., Simmons B.D., Mignoli M., Zamorani G., Vignali C., Brusa M., Shankar F., Lutz D., Trump J.R., Maiolino R., Gilli R., Bolzonella M., Puccetti S., Salvato M., Impey C.D., Civano F., Elvis M., Mainieri V., Silverman J.D., Koekemoer A.M., Bongiorno A., A. Merloni, Berta S., Le Floc'h E., Magnelli B., Pozzi F., Riguccini L., Harvard University-Smithsonian Institution, Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Galaxies: active, Galaxies: evolution, Methods: statistical, Quasars: general, Astronomy and Astrophysics, Space and Planetary Science, [PHYS]Physics [physics], methods: statistical, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, quasars: general, Astrophysics::Solar and Stellar Astrophysics, galaxies: evolution, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Bolometric luminosities and Eddington ratios of both X-ray selected broad-line (Type-1) and narrow-line (Type-2) AGN from the XMM-Newton survey in the COSMOS field are presented. The sample is composed by 929 AGN (382 Type-1 AGN and 547 Type-2 AGN) and it covers a wide range of redshifts, X-ray luminosities and absorbing column densities. About 65% of the sources are spectroscopically identified as either Type-1 or Type-2 AGN (83% and 52% respectively), while accurate photometric redshifts are available for the rest of the sample. The study of such a large sample of X-ray selected AGN with a high quality multi-wavelength coverage from the far-infrared (now with the inclusion of Herschel data at 100 micron and 160 micron) to the optical-UV allows us to obtain accurate estimates of bolometric luminosities, bolometric corrections and Eddington ratios. The kbol-Lbol relations derived in the present work are calibrated for the first time against a sizable AGN sample, and rely on observed redshifts, X-ray luminosities and column density distributions. We find that kbol is significantly lower at high Lbol with respect to previous estimates by Marconi et al. (2004) and Hopkins et al. (2007). Black hole masses and Eddington ratios are available for 170 Type-1 AGN, while black hole masses for Type-2 AGN are computed for 481 objects using the black hole mass-stellar mass relation and the morphological information. We confirm a trend between kbol and lambda_Edd, with lower hard X-ray bolometric corrections at lower Eddington ratios for both Type-1 and Type-2 AGN. We find that, on average, Eddington ratio increases with redshift for all Types of AGN at any given Mbh, while no clear evolution with redshift is seen at any given Lbol., Comment: 19 pages, 18 figures, accepted to MNRAS

Published
2012
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6. LATE-STAGE GALAXY MERGERS IN COSMOS TO z similar to 1

Author

Lackner, C. N., Silverman, J. D., Salvato, M., Kampczyk, P., Kartaltepe, J. S., Sanders, D., Capak, P., Civano, F., Halliday, C., Ilbert, O., Jahnke, K., Koekemoer, A. M., Lee, N., Le Fevre, O., Liu, C. T., Scoville, N., Sheth, K., Toft, S., Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

International audience; The role of major mergers in galaxy and black hole formation is not well-constrained. To help address this, we develop an automated method to identify late-stage galaxy mergers before coalescence of the galactic cores. The resulting sample of mergers is distinct from those obtained using pair-finding and morphological indicators. Our method relies on median-filtering of high-resolution images to distinguish two concentrated galaxy nuclei at small separations. This method does not rely on low surface brightness features to identify mergers, and is therefore reliable to high redshift. Using mock images, we derive statistical contamination and incompleteness corrections for the fraction of late-stage mergers. The mock images show that our method returns an uncontaminated (\textless10%) sample of mergers with projected separations between 2.2 and 8 kpc out to z similar to 1. We apply our new method to a magnitude-limited (m(FW 814) \textless 23) sample of 44,164 galaxies from the COSMOS HST/ACS catalog. Using a mass-complete sample with log M-*/M-circle dot \textgreater 10.6 and 0.25 \textless z \textless= 1.00, we find similar to 5% of systems are late-stage mergers. Correcting for incompleteness and contamination, the fractional merger rate increases strongly with redshift as R-merge proportional to (1 + z)(3.8 +/- 0.9), in agreement both with earlier studies and with dark matter halo merger rates. Separating the sample into star-forming and quiescent galaxies shows that the merger rate for star-forming galaxies increases strongly with redshift, (1 + z)(4.5 +/- 1.3), while the merger rate for quiescent galaxies is consistent with no evolution, (1 + z)(1.1 +/- 1.2). The merger rate also becomes steeper with decreasing stellar mass. Limiting our sample to galaxies with spectroscopic redshifts from zCOSMOS, we find that the star formation rates and X-ray selected active galactic nucleus (AGN) activity in likely late-stage mergers are higher by factors of similar to 2 relative to those of a control sample. Combining our sample with more widely separated pairs, we find that 8 +/- 5% of star formation and 20 +/- 8% of AGN activity are triggered by close encounters (\textless143 kpc) or mergers, providing additional evidence that major mergers are not the only channels for star formation and black hole growth.

Published
2014
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7. SPECTROSCOPY OF LUMINOUS z \textgreater 7 GALAXY CANDIDATES AND SOURCES OF CONTAMINATION IN z \textgreater 7 GALAXY SEARCHES

Author

Capak, P., Mobasher, B., Scoville, N. Z., McCracken, H., Ilbert, O., Salvato, M., Menendez-Delmestre, K., Aussel, H., Carilli, C., Civano, F., Elvis, M., Giavalisco, M., Jullo, E., Kartaltepe, J., Leauthaud, A., Koekemoer, A. M., Kneib, J. -P., LeFloch, E., Sanders, D. B., Schinnerer, E., Shioya, Y., Shopbell, P., Tanaguchi, Y., Thompson, D., Willott, C. J., Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
Abstract

International audience; We present three bright z(+)-dropout candidates selected from deep near-infrared (NIR) imaging of the COSMOS 2 deg(2) field. All three objects match the 0.8-8 mu m colors of other published z \textgreater 7 candidates but are 3 mag brighter, facilitating further study. Deep spectroscopy of two of the candidates covering 0.64-1.02 mu m with Keck-DEIMOS and all three covering 0.94-1.10 mu m and 1.52-1.80 mu m with Keck-NIRSPEC detects weak spectral features tentatively identified as Ly alpha at z = 6.95 and z = 7.69 in two of the objects. The third object is placed at z similar to 1.6 based on a 24 mu m and weak optical detection. A comparison with the spectral energy distributions of known z \textless 7 galaxies, including objects with strong spectral lines, large extinction, and large systematic uncertainties in the photometry, yields no objects with similar colors. However, the lambda \textgreater 1 mu m properties of all three objects can be matched to optically detected sources with photometric redshifts at z similar to 1.8, so the non-detection in the i(+) and z(+) bands is the primary factor which favors a z \textgreater 7 solution. If any of these objects are at z similar to 7, the bright end of the luminosity function is significantly higher at z \textgreater 7 than suggested by previous studies, but consistent within the statistical uncertainty and the dark matter halo distribution. If these objects are at low redshift, the Lyman break selection must be contaminated by a previously unknown population of low-redshift objects with very strong breaks in their broadband spectral energy distributions and blue NIR colors. The implications of this result on luminosity function evolution at high redshift are discussed. We show that the primary limitation of z \textgreater 7 galaxy searches with broad filters is the depth of the available optical data.

Published
2011
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8. Ultraluminous X-ray sources out to z ~ 0.3 in the COSMOS field

Author

Angela Bongiorno, O. Le Fèvre, John D. Silverman, N. Z. Scoville, P. Franzetti, Anton M. Koekemoer, Olga Cucciati, E. Zucca, Simonetta Puccetti, C. Knobel, Thierry Contini, S. Bardelli, Bianca Garilli, Giuseppina Fabbiano, G. Zamorani, Antonella Fruscione, L. de Ravel, E. Perez Montero, Jonathan R. Trump, Nico Cappelluti, Andrea Merloni, Mara Salvato, Cristian Vignali, M. Scodeggio, J. P. Kneib, K. Kovac, Alvio Renzini, Lidia Tasca, Y. Peng, S. de la Torre, Peter Capak, Alexis Finoguenov, Graziano Coppa, Francesca Civano, Roberto Gilli, Tom Aldcroft, Fabrizio Fiore, P. Kampczyk, V. Mainieri, F. Lamareille, Monique Aller, Chris Impey, R. Pello, Andrea Comastri, M. Bolzonella, M. Mignoli, Laurence Tresse, Martin Elvis, M. Carollo, Yoshiaki Taniguchi, Simon J. Lilly, Claudia Scarlata, Masayuki Tanaka, Karina Caputi, V. Le Brun, E. Ricciardelli, Christian Maier, Olivier Ilbert, Marcella Brusa, A. Iovino, J. F. Le Borgne, Daniela Vergani, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Astronomy, Mainieri V., Vignali C., Merloni A., Civano F., Puccetti S., Brusa M., Gilli R., Bolzonella M., Comastri A., Zamorani G., Aller M., Carollo M., Scarlata C., Elvis M., Aldcroft T.L., Cappelluti N., Fabbiano G., Finoguenov A., Fiore F., Fruscione A., Koekemoer A.M., Contini T., Kneib J.P., Le Fevre O., Lilly S., Renzini A., Scodeggio M., Bardelli S., Bongiorno A., Caputi K., Coppa G., Cucciati O., de la Torre S., de Ravel L., Franzetti P., Garilli B., Iovino A., Kampczyk P., Knobel C., Kovac K., Lamareille F., Le Borgne J.F., Le Brun V., Maier C., Mignoli M., Pello R., Peng Y., Perez Montero E., Ricciardelli E., Silverman J.D., Tanaka M., Tasca L., Tresse L., Vergani D., Zucca E., Capak P., Ilbert O., Impey C., Salvato M., Scoville S., Taniguchi Y., and Trump L.

Subjects
X-rays: galaxies – X-rays: binaries – X-rays: general – surveys, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Field (physics), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, X-rays: general, 01 natural sciences, X-rays: binaries, surveys, 0103 physical sciences, [INFO]Computer Science [cs], 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Star formation, X-ray, Astronomy and Astrophysics, Redshift, Galaxy, Early type, X-rays: galaxies, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Using Chandra observations we have identified a sample of seven off-nuclear X-ray sources, in the redshift range z=0.072-0.283, located within optically bright galaxies in the COSMOS Survey. Using the multi-wavelength coverage available in the COSMOS field, we study the properties of the host galaxies of these ULXs. In detail, we derived their star formation rate from H_alpha measurements and their stellar masses using SED fitting techniques with the aim to compute the probability to have an off-nuclear source based on the host galaxy properties. We divide the host galaxies in different morphological classes using the available ACS/HST imaging. We find that our ULXs candidates are located in regions of the SFR versus M$_star$ plane where one or more off-nuclear detectable sources are expected. From a morphological analysis of the ACS imaging and the use of rest-frame colours, we find that our ULXs are hosted both in late and early type galaxies. Finally, we find that the fraction of galaxies hosting a ULX ranges from ~0.5% to ~0.2% going from L[0.5-2 keV]=3 x 10^39 erg s^-1 to L[0.5-2 keV]= 2 x 10^40 erg s^-1., Comment: 10 pages, 9 figures, accepted for publication in Astronomy & Astrophysics

Published
2010
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9. The Environments of Active Galactic Nuclei within the zCOSMOS Density Field

Author

O. Cucciati, Pascal Oesch, S. de la Torre, R. Pello, M. Mignoli, P. Kampczyk, C. M. Carollo, F. Lamareille, D. Bottini, Andrea Comastri, J. F. Le Borgne, Graziano Coppa, E. Zucca, E. Ricciardelli, Marco Scodeggio, S. Bardelli, Christian Maier, T. Contini, Knud Jahnke, Mara Salvato, Vincenzo Mainieri, E. Perez Montero, H. J. McCracken, Roberto Gilli, M. Elvis, P. Memeo, Jean-Paul Kneib, Christian Marinoni, Richard E. Griffiths, A. Finoguenov, L. Tresse, P. Franzetti, A. Cappi, Paolo Cassata, D. Vergani, C. Knobel, G. Hasinger, Angela Bongiorno, John D. Silverman, G. Zamorani, L. de Ravel, O. Le Fevre, Francesca Civano, B. Garilli, Y. Peng, Katarina Kovac, V. Le Brun, Nico Cappelluti, Masaomi Tanaka, M. Bolzonella, Cristian Vignali, Karina Caputi, L. A. M. Tasca, Fabrizio Fiore, Hermann Brunner, S. J. Lilly, M. Fumana, Cristiano Porciani, A. Iovino, B. Meneux, Marcella Brusa, Institute of Astronomy [ETH Zürich], Department of Physics [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), Max-Planck-Institut für Extraterrestrische Physik (MPE), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Universitats-Sternwarte [München], Ludwig-Maximilians-Universität München (LMU), INAF - Osservatorio Astronomico di Brera (OAB), INAF - Osservatorio Astronomico di Roma (OAR), INAF-IASF Milano, Carnegie Mellon University [Pittsburgh] (CMU), Space Telescope Science Institute (STSci), Universita degli Studi di Padova, Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Centre de Physique Théorique - UMR 7332 (CPT), Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), California Institute of Technology (CALTECH), Silverman J. D., Kovac K., Knobel C., Lilly S., Bolzonella M., Lamareille F., Mainieri V., Brusa M., Cappelluti N., Peng Y., Hasinger G., Zamorani G., Scodeggio M., Contini T., Carollo C. M., Jahnke K., Kneib J.-P., LeFevre O., Bardelli S., Bongiorno A., Brunner H., Caputi K., Civano F., Comastri A., Coppa G., Cucciati O., de la Torre S., de Ravel L., Elvis M., Finoguenov A., Fiore F., Franzetti P., Garilli B., Gilli R., Griffiths R., Iovino A., Kampczyk P., Koekemoer A., LeBorgne J.-F., LeBrun V., Maier C., Mignoli M., Pello R., Perez Montero E., Ricciardelli E., Tanaka M., Tasca L., Tresse L., Vergani D., Vignali C., Zucca E., Bottini D., Cappi A., Cassata P., Marinoni C., McCracken H. J., Memeo P., Meneux B., Oesch P., Porciani C., Salvato M., AUTRES, Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (LATT), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, University of Chicago, Max-Planck-Institut für Astronomie (MPIA), INAF- Milano, INAF - Osservatorio Astronomico di Capodimonte (OAC), UPRESA, Centre National de la Recherche Scientifique (CNRS), Université de la Méditerranée - Aix-Marseille 2, Department of Statistics [Oxford], University of Oxford [Oxford], Services communs OMP (UMS 831), Glycosciences Laboratory, Imperial College School of Medicine, Information Science Laboratory, Tokai University, Japan Atomic Energy Agency, Centre de Physique Théorique - UMR 6207 (CPT), Université de la Méditerranée - Aix-Marseille 2-Université de Provence - Aix-Marseille 1-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), and Università degli Studi di Padova = University of Padua (Unipd)

Subjects
Active galactic nucleus, Stellar mass, Galaxies: active, Quasars: general, X-rays: galaxies, Astronomy and Astrophysics, Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, Population, galaxies: active, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], quasars: general, 0103 physical sciences, Density field, education, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, education.field_of_study, 010308 nuclear & particles physics, Star formation, Astrophysics (astro-ph), Significant difference, Redshift survey, Galaxy, Astrophysics::Earth and Planetary Astrophysics, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], galaxies: active – quasars: general – X-rays: galaxies
Abstract

The impact of environment on AGN activity up to z~1 is assessed by utilizing a mass-selected sample of galaxies from the 10k catalog of the zCOSMOS spectroscopic redshift survey. We identify 147 AGN by their X-ray emission as detected by XMM-Newton from a parent sample of 7234 galaxies. We measure the fraction of galaxies with stellar mass M_*>2.5x10^10 Msun that host an AGN as a function of local overdensity using the 5th, 10th and 20th nearest neighbors that cover a range of physical scales (~1-4 Mpc). Overall, we find that AGNs prefer to reside in environments equivalent to massive galaxies with substantial levels of star formation. Specifically, AGNs with host masses between 0.25-1x10^11 Msun span the full range of environments (i.e., field-to-group) exhibited by galaxies of the same mass and rest-frame color or specific star formation rate. Host galaxies having M_*>10^11 Msun clearly illustrate the association with star formation since they are predominantly bluer than the underlying galaxy population and exhibit a preference for lower density regions analogous to SDSS studies of narrow-line AGN. To probe the environment on smaller physical scales, we determine the fraction of galaxies (M_*>2.5x10^10 Msun) hosting AGNs inside optically-selected groups, and find no significant difference with field galaxies. We interpret our results as evidence that AGN activity requires a sufficient fuel supply; the probability of a massive galaxy to have retained some sufficient amount of gas, as evidence by its ongoing star formation, is higher in underdense regions where disruptive processes (i.e., galaxy harrassment, tidal stripping) are lessened., 13 pages; 11 figures; To appear in The Astrophysical Journal

Published
2009
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