Cosmological Evolution of the AGN X-ray Luminosity Function

To reveal the cosmological evolution of the X-ray luminosity function (XLF) of Active Galactic Nuclei (AGN) has been a main goal of X-ray astronomy. Here we present the results of a statistical analysis of the AGNs XLF utilizing the largest sample ever available, combined from surveys of various depth and area with HEAO1, ROSAT, ASCA, Chandra, and XMM. The use of hard-band (above 2 keV) and soft-band selected samples enables us to determine the intrinsic XLF and the absorption distribution function of type-I plus type-II AGNs with an unprecedented accuracy, establishing the population synthesis of the X-ray background.