X-RAY EVOLUTION OF ACTIVE GALACTIC NUCLEI IN HIERARCHICAL GALAXY FORMATION

摘要

We have incorporated the description of the X-ray properties of Active Galactic Nuclei (AGNs) into a semi-analytic model of galaxy formation, adopting physically motivated scaling laws for accretion triggered by galaxy encounters. Our model reproduces the level of the cosmic X-ray background at 30keV; we predict that the largest contribution (around 2/3) comes from sources with intermediate X-ray luminosity 10{sup}43.510{sup}44.5erg/s in the 2-10keV band) it peaks at z≈2 with a decline of around 3 dex to z=0; for the low luminosity sources (10{sup}43