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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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