Clusters of Galaxies in X-rays: Dark Matter

Abstract

We present the analysis of baryonic and non-baryonic matter distribution in a sample of ten nearby clusters ($0.03<z<0.09$) with temperatures between 4.7 and 9.4 keV. These galaxy clusters have been studied in detail using X-ray data and global physical properties have been determined. Correlations between these quantities have been analysed and compared with the results for distant clusters. We found an interesting dependence between the relative gas extent (expressed as the ratio of gas mass fractions at $r_{500}$ and $0.5\times r_{500}$) and the total cluster mass. The extent of the gas relative to the extent of the dark matter tends to be larger in less massive clusters. This dependence might give us some hints about non-gravitational processes in clusters. The new X-ray satellites Chandra and XMM yield exciting new results for galaxy cluster physics and cosmology. We show the interesting X-ray observations of two intermediate redshift clusters, RBS797 ($z=0.35$) and CL 0939+4713 ($z=0.41$) taken with Chandra and XMM respectively.