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The host galaxies and black holes of typical z\~0.5-1.4 AGNs.

Alonso-Herrero, A. and Pérez-González, P.G. and Rieke, G.H. and Alexander, D.M. and Rigby, J.R. and Papovich, C. and Donley, J.L. and Rigopoulou, D. (2008) 'The host galaxies and black holes of typical z\~0.5-1.4 AGNs.', Astrophysical journal., 677 (1). pp. 127-136.


We study the stellar and star formation properties of the host galaxies of 58 X-ray-selected AGNs in the GOODS portion of the Chandra Deep Field South (CDF-S) region at z~0.5-1.4. The AGNs are selected such that their rest-frame UV to near-infrared spectral energy distributions (SEDs) are dominated by stellar emission; i.e., they show a prominent 1.6 μm bump, thus minimizing the AGN emission ``contamination.'' This AGN population comprises approximately 50% of the X-ray-selected AGNs at these redshifts. We find that AGNs reside in the most massive galaxies at the redshifts probed here. Their characteristic stellar masses (M*~7.8×1010 and M*~1.2×1011 Msolar at median redshifts of 0.67 and 1.07, respectively) appear to be representative of the X-ray-selected AGN population at these redshifts and are intermediate between those of local type 2 AGNs and high-redshift (z~2) AGNs. The inferred black hole masses (MBH~2×108 Msolar) of typical AGNs are similar to those of optically identified quasars at similar redshifts. Since the AGNs in our sample are much less luminous (L2-10keV<1044 erg s-1) than quasars, typical AGNs have low Eddington ratios (η~0.01-0.001). This suggests that, at least at intermediate redshifts, the cosmic AGN ``downsizing'' is due to both a decrease in the characteristic stellar mass of typical host galaxies and less efficient accretion. Finally, there is no strong evidence in AGN host galaxies for either highly suppressed star formation (expected if AGNs played a role in quenching star formation) or elevated star formation when compared to mass-selected (i.e., IRAC-selected) galaxies of similar stellar masses and redshifts.

Item Type:Article
Keywords:Galaxies, Active, Evolution, High-redshift, Stellar content, Infrared.
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Publisher statement:© 2008. The American Astronomical Society. All rights reserved. Printed in the U.S.A.
Date accepted:No date available
Date deposited:05 September 2013
Date of first online publication:April 2008
Date first made open access:No date available

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