The Space Density of Compton-Thick Active Galactic Nucleus and the X-Ray Background

摘要: We constrain the number density and evolution of Compton-thick (CT) active galactic nuclei (AGNs). In local universe, we use wide-area surveys from Swift INTEGRAL satellites, while for high redshifts explore candidate selections based on a combination X-ray mid-infrared (mid-IR) parameters. find significantly lower space CT AGNs in universe than expected published AGN population synthesis models to explain background (XRB). This can be explained by numerous degeneracies parameters those models; high-energy described here remove degeneracies. show that only direct observations currently heavily obscured supermassive black holes. At redshift, inclusion IR-selected candidates leads much higher density, implying (1) different (steeper) these sources compared less-obscured AGNs, (2) IR selection includes large interlopers, and/or (3) there is reflection-dominated missed observations. The contribution XRB small, ~9%, with comparable total cosmic accretion, unless outnumber transmission-dominated which case their higher. Using estimates derived accretion luminosity over time, estimate mass holes good agreement available constraints an efficiency ~10%. Transmission-dominated contribute ~8% hole growth.