TY - JOUR
T1 - Host galaxies, clustering, Eddington ratios, and evolution of radio, X-ray, and infrared-selected AGNs
AU - Hickox, Ryan C.
AU - Jones, Christine
AU - Forman, William R.
AU - Murray, Stephen S.
AU - Kochanek, Christopher S.
AU - Eisenstein, Daniel
AU - Jannuzi, Buell T.
AU - Dey, Arjun
AU - Brown, Michael J.I.
AU - Stern, Daniel
AU - Eisenhardt, Peter R.
AU - Gorjian, Varoujan
AU - Brodwin, Mark
AU - Narayan, Ramesh
AU - Cool, Richard J.
AU - Kenter, Almus
AU - Caldwell, Nelson
AU - Anderson, Michael E.
PY - 2009/5/1
Y1 - 2009/5/1
N2 - 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 Mhalo ∼ 3 × 1013 h-1 M⊙), and have very low Eddington ratios λ ≲ 10-3; (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 (Mhalo ∼ 1013 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 ≲ 1012h-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 ∼ 1012 and 1013 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.
AB - 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 Mhalo ∼ 3 × 1013 h-1 M⊙), and have very low Eddington ratios λ ≲ 10-3; (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 (Mhalo ∼ 1013 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 ≲ 1012h-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 ∼ 1012 and 1013 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.
KW - Galaxies: active
KW - Large-scale structure of universe
KW - Quasars: general
KW - Radio continuum: galaxies
KW - Surveys
KW - X-rays: galaxies
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U2 - 10.1088/0004-637X/696/1/891
DO - 10.1088/0004-637X/696/1/891
M3 - Article
AN - SCOPUS:66649099024
SN - 0004-637X
VL - 696
SP - 891
EP - 919
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
ER -