AGN Unification at z ~ 1: u – R Colors and Gradients in X-Ray AGN Hosts

We present uncontaminated rest-frame u -- R colors of 78 X-ray-selected active galactic nucleus (AGN) hosts at 0.5 < z < 1.5 in the Chandra Deep Fields measured with Hubble Space Telescope (HST)/Advanced Camera for Surveys/NICMOS and Very Large Telescope/ISAAC imaging. We also present spatiall...

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Veröffentlicht in:The Astrophysical journal 2011-10, Vol.740 (1), p.3-jQuery1323902660176='48'
Hauptverfasser: Mark Ammons, S, Rosario, David J. V, Koo, David C, Dutton, Aaron A, Melbourne, Jason, Max, Claire E, Mozena, Mark, Kocevski, Dale D, McGrath, Elizabeth J, Bouwens, Rychard J, Magee, Daniel K
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Sprache:eng
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Zusammenfassung:We present uncontaminated rest-frame u -- R colors of 78 X-ray-selected active galactic nucleus (AGN) hosts at 0.5 < z < 1.5 in the Chandra Deep Fields measured with Hubble Space Telescope (HST)/Advanced Camera for Surveys/NICMOS and Very Large Telescope/ISAAC imaging. We also present spatially resolved NUV -- R color gradients for a subsample of AGN hosts imaged by HST/Wide Field Camera 3 (WFC3). Integrated, uncorrected photometry is not reliable for comparing the mean properties of soft and hard AGN host galaxies at z ~ 1 due to color contamination from point-source AGN emission. We use a cloning simulation to develop a calibration between concentration and this color contamination and use this to correct host galaxy colors. The mean u -- R color of the unobscured/soft hosts beyond ~6 kpc is statistically equivalent to that of the obscured/hard hosts (the soft sources are 0.09 ? 0.16 mag bluer). Furthermore, the rest-frame V -- J colors of the obscured and unobscured hosts beyond ~6 kpc are statistically equivalent, suggesting that the two populations have similar distributions of dust extinction. For the WFC3/infrared sample, the mean NUV -- R color gradients of unobscured and obscured sources differ by less than ~0.5 mag for r > 1.1 kpc. These three observations imply that AGN obscuration is uncorrelated with the star formation rate beyond ~1 kpc. These observations favor a unification scenario for intermediate-luminosity AGNs in which obscuration is determined geometrically. Scenarios in which the majority of intermediate-luminosity AGNs at z ~ 1 are undergoing rapid, galaxy-wide quenching due to AGN-driven feedback processes are disfavored.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/740/1/3