THE CONTRIBUTION OF QUASARS TO THE 2KEV-100 MEV BACKGROUND-RADIATION AND X-RAY SOURCE COUNTS AT 2KEV

We estimate the contribution of quasars to the X- and 7-ray background, using the rates of evolution we have previously found necessary to explain the optical source counts of quasars. With plausible assumptions about the optical—X-ray spectral index, aox, we are able to present a self-consistent picture in which the background intensity {and spectral shape) from 2 keV—100 MeV is produced almost entirely by quasars and a significant fraction of the counts of unidentified extragalactic X-ray sources at 2 keV are explained. © Royal Astronomical Society.