Ammons, S. Mark and Rosario, David J. V. and Koo, David C. and Dutton, Aaron A. and Melbourne, Jason and Max, Claire E. and Mozena, Mark and Kocevski, Dale D. and McGrath, Elizabeth J. and Bouwens, Rychard J. and Magee, Daniel K. (2011) AGN Unification at z ~ 1: u – R Colors and Gradients in X-Ray AGN Hosts. Astrophysical Journal, 740 (1). Art. No. 3. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20111107-072844464
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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.
|Additional Information:||© 2011 American Astronomical Society. Received 2010 December 22; accepted 2011 July 8; published 2011 September 16. This work has been supported in part by the NSF Science and Technology Center for Adaptive Optics, managed by the University of California (UC) at Santa Cruz under the cooperative agreement No. AST-9876783. Some of the data presented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NAG5-7584 and by other grants and contracts. Support for Program number HST-HF-51250.01-A was provided by NASA through a Hubble Fellowship grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. S.M.A. acknowledges fellowship support by the Allen family through UC Observatories/Lick Observatory. This work is based in part on observations made with the European Southern Observatory telescopes obtained from the ESO/ST-ECF Science Archive Facility. Observations have been carried out using the Very Large Telescope at the ESO Paranal Observatory under Program ID(s): LP168.A-0485. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The document release number is LLNL-JRNL-490659.|
|Subject Keywords:||galaxies: active; galaxies: evolution; galaxies: photometry; galaxies: stellar content; X-rays: galaxies|
|Classification Code:||PACS: 98.54.Cm; 98.62.Ck; 98.62.Ai; 98.62.Lv; 98.62.Qz; 98.62.Js|
|Official Citation:||AGN Unification at z ~ 1: u – R Colors and Gradients in X-Ray AGN Hosts S. Mark Ammons et al. 2011 ApJ 740 3|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||07 Nov 2011 16:01|
|Last Modified:||26 Dec 2012 14:22|
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