Accretion to the cluster of galaxies and x-ray emission

The X-ray emission from a cluster of galaxies, in particular, from Coma cluster is investigated for the case of steady and spherically symmetric accretion of hot intercluster plasma. The luminosity, the emission region and the X-ray spectrum in 0.1-20 keV region are well explained by this model. It is also shown that the diffuse background X-ray below 20 keV is explained by superpositions of all clusters and of hot intercluster plasma. Also, the thermal structure and history of the universe are discussed. (auth.)