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Title: THE XMM-NEWTON WIDE FIELD SURVEY IN THE COSMOS FIELD: REDSHIFT EVOLUTION OF AGN BIAS AND SUBDOMINANT ROLE OF MERGERS IN TRIGGERING MODERATE-LUMINOSITY AGNs AT REDSHIFTS UP TO 2.2

Abstract

We present a study of the redshift evolution of the projected correlation function of 593 X-ray selected active galactic nuclei (AGNs) with I{sub AB} < 23 and spectroscopic redshifts z < 4, extracted from the 0.5-2 keV X-ray mosaic of the 2.13 deg{sup 2} XMM- Cosmic Evolution Survey (COSMOS). We introduce a method to estimate the average bias of the AGN sample and the mass of AGN hosting halos, solving the sample variance using the halo model and taking into account the growth of the structure over time. We find evidence of a redshift evolution of the bias factor for the total population of XMM-COSMOS AGNs from b-bar (z-bar =0.92)=2.30{+-}0.11 to b-bar (z-bar =1.94)=4.37{+-}0.27 with an average mass of the hosting dark matter (DM) halos log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.12 {+-} 0.12 that remains constant at all z < 2. Splitting our sample into broad optical line AGNs (BL), AGNs without broad optical lines (NL), and X-ray unobscured and obscured AGNs, we observe an increase of the bias with redshift in the range z-bar = 0.7-2.25 and z-bar = 0.6-1.5 which corresponds to a constant halo mass of log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.28 {+-}more » 0.07 and log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.00 {+-} 0.06 for BL/X-ray unobscured AGNs and NL/X-ray obscured AGNs, respectively. The theoretical models, which assume a quasar phase triggered by major mergers, cannot reproduce the high bias factors and DM halo masses found for X-ray selected BL AGNs with L{sub BOL} {approx} 2 x 10{sup 45} erg s{sup -1}. Our work extends up to z {approx} 2.2 the z {approx}< 1 statement that, for moderate-luminosity X-ray selected BL AGNs, the contribution from major mergers is outnumbered by other processes, possibly secular ones such as tidal disruptions or disk instabilities.« less

Authors:
; ;  [1]; ; ; ;  [2];  [3];  [4]; ; ;  [5];  [6]; ;  [7];  [8];  [9]
  1. Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany)
  2. Max-Planck-Institute fuer Extraterrestrische Physik, D-85748 Garching (Germany)
  3. Center for Space Science Technology, University of Maryland, Baltimore County, Baltimore, MD 21250 (United States)
  4. Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ensenada (Mexico)
  5. INAF-Osservatorio Astronomico di Bologna, 40127 Bologna (Italy)
  6. Max-Planck-Institute fuer Astrophysik, D-85748 Garching (Germany)
  7. Astronomy Department, University of California, Berkeley, Berkeley CA 94720-7450 (United States)
  8. Observatoire de Paris, LERMA, 75014 Paris (France)
  9. Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa-shi, Chiba 277-8583 (Japan)
Publication Date:
OSTI Identifier:
21578267
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 736; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/736/2/99; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CORRELATION FUNCTIONS; GALACTIC EVOLUTION; GALAXY NUCLEI; LUMINOSITY; QUASARS; RED SHIFT; COSMIC RADIO SOURCES; EVOLUTION; FUNCTIONS; OPTICAL PROPERTIES; PHYSICAL PROPERTIES

Citation Formats

Allevato, V., Hasinger, G., Salvato, M., Finoguenov, A., Brusa, M., Bongiorno, A., Merloni, A., Cappelluti, N., Miyaji, T., Gilli, R., Zamorani, G., Comastri, A., Shankar, F., James, J. B., Peacock, J. A., McCracken, H. J., and Silverman, J. THE XMM-NEWTON WIDE FIELD SURVEY IN THE COSMOS FIELD: REDSHIFT EVOLUTION OF AGN BIAS AND SUBDOMINANT ROLE OF MERGERS IN TRIGGERING MODERATE-LUMINOSITY AGNs AT REDSHIFTS UP TO 2.2. United States: N. p., 2011. Web. doi:10.1088/0004-637X/736/2/99.
Allevato, V., Hasinger, G., Salvato, M., Finoguenov, A., Brusa, M., Bongiorno, A., Merloni, A., Cappelluti, N., Miyaji, T., Gilli, R., Zamorani, G., Comastri, A., Shankar, F., James, J. B., Peacock, J. A., McCracken, H. J., & Silverman, J. THE XMM-NEWTON WIDE FIELD SURVEY IN THE COSMOS FIELD: REDSHIFT EVOLUTION OF AGN BIAS AND SUBDOMINANT ROLE OF MERGERS IN TRIGGERING MODERATE-LUMINOSITY AGNs AT REDSHIFTS UP TO 2.2. United States. doi:10.1088/0004-637X/736/2/99.
Allevato, V., Hasinger, G., Salvato, M., Finoguenov, A., Brusa, M., Bongiorno, A., Merloni, A., Cappelluti, N., Miyaji, T., Gilli, R., Zamorani, G., Comastri, A., Shankar, F., James, J. B., Peacock, J. A., McCracken, H. J., and Silverman, J. Mon . "THE XMM-NEWTON WIDE FIELD SURVEY IN THE COSMOS FIELD: REDSHIFT EVOLUTION OF AGN BIAS AND SUBDOMINANT ROLE OF MERGERS IN TRIGGERING MODERATE-LUMINOSITY AGNs AT REDSHIFTS UP TO 2.2". United States. doi:10.1088/0004-637X/736/2/99.
@article{osti_21578267,
title = {THE XMM-NEWTON WIDE FIELD SURVEY IN THE COSMOS FIELD: REDSHIFT EVOLUTION OF AGN BIAS AND SUBDOMINANT ROLE OF MERGERS IN TRIGGERING MODERATE-LUMINOSITY AGNs AT REDSHIFTS UP TO 2.2},
author = {Allevato, V. and Hasinger, G. and Salvato, M. and Finoguenov, A. and Brusa, M. and Bongiorno, A. and Merloni, A. and Cappelluti, N. and Miyaji, T. and Gilli, R. and Zamorani, G. and Comastri, A. and Shankar, F. and James, J. B. and Peacock, J. A. and McCracken, H. J. and Silverman, J.},
abstractNote = {We present a study of the redshift evolution of the projected correlation function of 593 X-ray selected active galactic nuclei (AGNs) with I{sub AB} < 23 and spectroscopic redshifts z < 4, extracted from the 0.5-2 keV X-ray mosaic of the 2.13 deg{sup 2} XMM- Cosmic Evolution Survey (COSMOS). We introduce a method to estimate the average bias of the AGN sample and the mass of AGN hosting halos, solving the sample variance using the halo model and taking into account the growth of the structure over time. We find evidence of a redshift evolution of the bias factor for the total population of XMM-COSMOS AGNs from b-bar (z-bar =0.92)=2.30{+-}0.11 to b-bar (z-bar =1.94)=4.37{+-}0.27 with an average mass of the hosting dark matter (DM) halos log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.12 {+-} 0.12 that remains constant at all z < 2. Splitting our sample into broad optical line AGNs (BL), AGNs without broad optical lines (NL), and X-ray unobscured and obscured AGNs, we observe an increase of the bias with redshift in the range z-bar = 0.7-2.25 and z-bar = 0.6-1.5 which corresponds to a constant halo mass of log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.28 {+-} 0.07 and log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.00 {+-} 0.06 for BL/X-ray unobscured AGNs and NL/X-ray obscured AGNs, respectively. The theoretical models, which assume a quasar phase triggered by major mergers, cannot reproduce the high bias factors and DM halo masses found for X-ray selected BL AGNs with L{sub BOL} {approx} 2 x 10{sup 45} erg s{sup -1}. Our work extends up to z {approx} 2.2 the z {approx}< 1 statement that, for moderate-luminosity X-ray selected BL AGNs, the contribution from major mergers is outnumbered by other processes, possibly secular ones such as tidal disruptions or disk instabilities.},
doi = {10.1088/0004-637X/736/2/99},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 736,
place = {United States},
year = {2011},
month = {8}
}