AGN models for the X and gamma-ray backgrounds

Abstract

The origin of the X-ray background spectral intensity has been a long standing problem in high energy astrophysics research. Deep X-ray surveys carried out with ROSAT and ASCA combined with the broad band spectral results of Ginga and BeppoSAX satellites strongly support the hypothesis that the bulk of the X-ray background is due to the integrated contribution of discrete sources (mainly AGNs). At higher energies the unexpected findings of the Compton Gamma Ray Observatory indicate that also the gamma-ray background is likely to be due to AGNs. I will discuss AGN--based models for the high energy backgrounds and how future observations will improve our understanding of the X and gamma-ray backgrounds and of the physics and evolution of AGNs.

8 pages, 4 figures. Invited talk presented at the 3rd INTEGRAL Workshop : The Extreme Universe, Taormina 14-18 Sept. 1998 Astrophysical Letters and Communications, in press