AGN EVOLUTION REVEALED FROM X-RAY SURVEYS

Yoshihiro Ueda
unpublished
I review the cosmological evolution of Active Galac-tic Nuclei (AGNs) revealed from X-ray surveys, mainly based on studies by using hard (>2 keV) X-ray selected samples. The hard X-ray luminosity function of type-1 and type-2 AGNs is well described by the luminosity dependent density evolution, where the cutoff redshift of density evolution increases with luminosity. This suggest anti-hierarchical (or down-sizing) growth of supermas-sive black holes in galactic centers. The black hole mass
more » ... lack hole mass function at z < 1 can be explained, on average, as the consequence of "standard" accretion with a radiative efficiency of ≈ 0.1. Population synthesis models constructed from the observational results of hard X-ray luminosity function and absorption function of AGNs are now close to finalization. However, toward complete understanding of the X-ray background origin, there still remains several issues to be solved by current and future missions.
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