Diffuse Background X Rays and the Density of the Intergalactic Medium

Abstract

Most of the 3-300 keY spectrum of the unresolved X-ray background can be explained as thermal bremsstrahlung from a hot intergalactic gas plus a small non-thermal component at higher energies. The model used assumes a static Universe with an exponential redshift with distance relationship that is due to photon interactions with curved space-time. The interglactic gas is found to have a temperature of 1 ·3 x 109 K and a density of 2.05 C - 213 hydrogen atoms m - 3, where C is an unknown factor that depends on the dumpiness of the intergalactic gas.