Spectral models for the diffuse X-ray background.

The major component of the X-ray sky is the diffuse X-ray background. For many years the origin of the X-ray background was a mystery; new observational data from satellites such as ROSAT, Ginga, Einstein and HEAO-1 have pointed the way to its understanding. In short the X-ray background is due to the combined emission of large numbers of faint unresolved sources, which are active galactic nuclei (AGN). The research is concentrates on calculating models of emission from AGN which are consistent with being the origin of the spectrum of the diffuse X-ray background. Resulting constraints on the AGN continuum spectra are derived.