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arXiv · 1107.2147

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

S. Mark Ammons·David J. V. Rosario·David C. Koo·Aaron A. Dutton·Jason Melbourne·Claire E. Max·Mark Mozena·Dale D. Kocevski·Elizabeth J. McGrath·Rychard J. Bouwens·Daniel K. Magee
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Abstract

We present uncontaminated rest-frame u - R colors of 78 X-ray-selected AGN hosts at 0.5 < z < 1.5 in the Chandra Deep Fields measured with HST/ACS/NICMOS and VLT/ISAAC imaging. We also present spatially-resolved NUV - R color gradients for a subsample of AGN hosts imaged by HST/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 magnitudes 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/IR sample, the mean NUV - R color gradients of unobscured and obscured sources differ by less than ~0.5 magnitudes 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 AGN at z ~ 1 are undergoing rapid, galaxy-wide quenching due to AGN-driven feedback processes are disfavored.

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S. Mark Ammons, David J. V. Rosario, David C. Koo, Aaron A. Dutton, Jason Melbourne, Claire E. Max, Mark Mozena, Dale D. Kocevski, Elizabeth J. McGrath, Rychard J. Bouwens, Daniel K. Magee. 2011-07-11. AGN Unification at z ~ 1: u - R Colors and Gradients in X-ray AGN Hosts. https://doi.org/10.1088/0004-637x/740/1/3

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