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Host Galaxies, Clustering, Eddington Ratios, and Evolution of Radio, X-Ray, and Infrared-Selected AGNs

Hickox, Ryan C. and Jones, Christine and Forman, William R. and Murray, Stephen S. and Kochanek, Christopher S. and Eisenstein, Daniel and Jannuzi, Buell T. and Dey, Arjun and Brown, Michael J. I. and Stern, Daniel and Eisenhardt, Peter R. and Gorjian, Varoujan and Brodwin, Mark and Narayan, Ramesh and Cool, Richard J. and Kenter, Almus and Caldwell, Nelson and Anderson, Michael E. (2009) Host Galaxies, Clustering, Eddington Ratios, and Evolution of Radio, X-Ray, and Infrared-Selected AGNs. Astrophysical Journal, 696 (1). pp. 891-919. ISSN 0004-637X.

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We explore the connection between different classes of active galactic nuclei (AGNs) and the evolution of their host galaxies, by deriving host galaxy properties, clustering, and Eddington ratios of AGNs selected in the radio, X-ray, and infrared (IR) wavebands. We study a sample of 585 AGNs at 0.25 < z < 0.8 using redshifts from the AGN and Galaxy Evolution Survey (AGES). We select AGNs with observations in the radio at 1.4 GHz from the Westerbork Synthesis Radio Telescope, X-rays from the Chandra XBoötes Survey, and mid-IR from the Spitzer IRAC Shallow Survey. The radio, X-ray, and IR AGN samples show only modest overlap, indicating that to the flux limits of the survey, they represent largely distinct classes of AGNs. We derive host galaxy colors and luminosities, as well as Eddington ratios, for obscured or optically faint AGNs. We also measure the two-point cross-correlation between AGNs and galaxies on scales of 0.3-10 h^(–1) Mpc, and derive typical dark matter halo masses. We find that: (1) radio AGNs are mainly found in luminous red sequence galaxies, are strongly clustered (with M_(halo) ~ 3 × 10^(13) h^(–1) M_☉ ), and have very low Eddington ratios λ10^(–3); (2) X-ray-selected AGNs are preferentially found in galaxies that lie in the "green valley" of color-magnitude space and are clustered similar to the typical AGES galaxies (M_(halo) ~ 10^(13) h^(–1) M_☉), with ≾10^(–3)λ≾ 1; (3) IR AGNs reside in slightly bluer, slightly less luminous galaxies than X-ray AGNs, are weakly clustered (M -(halo) ≾ 10^(12) h^(–1)M_☉), and have λ>10^(–2). We interpret these results in terms of a simple model of AGN and galaxy evolution, whereby a "quasar" phase and the growth of the stellar bulge occurs when a galaxy's dark matter halo reaches a critical mass between ~10^(12) and 10^(13)M_☉ . After this event, star formation ceases and AGN accretion shifts from radiatively efficient (optical- and IR-bright) to radiatively inefficient (optically faint, radio-bright) modes.

Item Type:Article
Related URLs:
URLURL TypeDescription
Hickox, Ryan C.0000-0003-1468-9526
Forman, William R.0000-0002-9478-1682
Kochanek, Christopher S.0000-0001-6017-2961
Jannuzi, Buell T.0000-0002-1578-6582
Dey, Arjun0000-0002-4928-4003
Brown, Michael J. I.0000-0002-1207-9137
Stern, Daniel0000-0003-2686-9241
Brodwin, Mark0000-0002-4208-798X
Narayan, Ramesh0000-0002-1919-2730
Additional Information:© 2009 The American Astronomical Society. Received 2008 September 19; accepted 2009 February 2; published 2009 April 20. We thank our colleagues on the NDWFS, AGES, IRAC Shallow Survey, and XBoötes teams. We thank Matthew Ashby, Anca Constantin, Alexey Vikhlinin, and Steven Willner for fruitful discussions, and thank the referee, Philip Hopkins, for helpful suggestions. We also thank Martin White for sharing dark matter simulation results. The NOAO Deep Wide-Field Survey, and the research of A.D. and B.T.J. are supported by NOAO, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under a cooperative agreement with the National Science Foundation. This paper would not have been possible without the efforts of the Chandra, Spitzer, KPNO, and MMT support staff. Optical spectroscopy discussed in this paper was obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. R.C.H. was supported by an SAO Postdoctoral Fellowship, NASA GSRP Fellowship, and Harvard Merit Fellowship, and by Chandra grants GO5-6130A and GO5-6121A.
Funding AgencyGrant Number
National Optical Astronomy Observatory (NOAO)UNSPECIFIED
Smithsonian Astrophysical ObservatorUNSPECIFIED
NASA Graduate Student Research FellowshipUNSPECIFIED
Harvard UniversityUNSPECIFIED
Subject Keywords:galaxies: active; large-scale structure of universe; quasars: general; radio continuum: galaxies; surveys; X-rays: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20090831-113934664
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Official Citation:Host Galaxies, Clustering, Eddington Ratios, and Evolution of Radio, X-Ray, and Infrared-Selected AGNs Ryan C. Hickox, Christine Jones, William R. Forman, Stephen S. Murray, Christopher S. Kochanek, Daniel Eisenstein, Buell T. Jannuzi, Arjun Dey, Michael J. I. Brown, Daniel Stern, Peter R. Eisenhardt, Varoujan Gorjian, Mark Brodwin, Ramesh Narayan, Richard J. Cool, Almus Kenter, Nelson Caldwell, and Michael E. Anderson 2009 ApJ 696 891-919 doi: 10.1088/0004-637X/696/1/891
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15486
Deposited By: Ruth Sustaita
Deposited On:11 Sep 2009 22:13
Last Modified:09 Mar 2020 13:18

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