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OATS-DAUT SEMINAR
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Speaker: Fabio La Franca (Univ. di Roma Tre)

Title: The evolution of active galactic nuclei

Date: Wednesday, December 6th, 2006
Time: 12:00 noon
Venue: Villa Bazzoni

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Abstract:
We will present the latest results on the cosmological evolution of the density of active galactic nuclei (AGNs) and of their NH distribution up to redshift 4. We used the HELLAS2XMM 2-10 keV X-ray sample combined with other published catalogs. Our best fit is obtained with a luminosity-dependent density evolution model where low-luminosity AGNs peak at z~0.7, while high-luminosity AGNs peak at z~2.0. There is evidence that the fraction of absorbed (NH>1022 cm-2) AGNs decreases with the intrinsic X-ray luminosity and increases with the redshift. Our results will be compared with the latest analyses on the density of AGN derived from mid-infrared surveys carried out with SPITZER. Using these data, we will present the estimate of the history of the density of supermassive black holes in the Universe.
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