Precursor active galaxies and the cosmic X-ray background

Abstract

Consideration is given to Carr's theory (1980) that most cosmic X-ray background is produced by thermal X-ray emission associated with black hole accretion disks for compact objects. It is posited that the onset of significant X-rays occurs during galaxy formation when accretion disks are formed by the interaction of young galaxies and massive black holes of pregalactic origin. The study suggests that most cosmic X-ray background could be produced from distant sources with a low ratio of optical to X-ray luminosity. Precursor active galaxy objects involving a massive black hole surrounded by a hot optically thin accretion disk radiating near the Eddington luminosity limit and with an effective temperature of about 2 x 10 to the 9th K would fulfill the condition and produce the correct background spectrum and intensity. This model also associates cosmic X-ray background and nonthermal gamma-ray background to active galaxies, thus implying that massive black holes are associated with their internal dynamics.