AGN unification and the X-ray background

被引:0
|
作者
Treister, E [1 ]
Urry, CM
Lira, P
机构
[1] Yale Univ, Dept Astron, New Haven, CT 06520 USA
[2] Univ Chile, Santiago, Chile
来源
PROCEEDINGS OF THE X-RAY UNIVERSE 2005, VOLS 1 AND 2 | 2006年 / 604卷
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中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The Great Observatories Origins Deep Survey (GOODS) combines deep HST and Spitzer imaging with the deepest Chandra/XMM observations to probe obscured AGN at higher redshifts than previous multiwavelength surveys. We present a self-consistent implementation of the AGN unification paradigm, which postulates obscured AGN wherever there are unobscured AGN, to successfully explain the infrared, optical, and X-ray number counts of X-ray sources detected in the GOODS fields. Assuming either a constant ratio of obscured to unobscured AGN of 3:1 (the local value), or a ratio that decreases with luminosity, and including Compton-thick sources, we can explain the spectral shape and normalization of the extragalactic X-ray "background" as a superposition of unresolved AGN, predominantly at z similar to 0.5-1.5 and L-x similar to 10(43)-10(44) ergs/s. The possible dependence of the obscured to unobscured ratio with redshift is not well constrained; present data allow it to decrease or increase substantially beyond z similar to 1.
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页码:845 / +
页数:2
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