ASCA Observations of Distant Clusters of Galaxies

Abstract

Investigation of evolution of X-ray properties of clusters of galaxies is a key study of cosmology. The most important result in this field before ROSAT and ASCA observatories is the detection of the negative evolution of the X-ray luminosity function at red-shift lower than 0.6 (Gioia et al., 1990). Following it, many groups have been investigating evolution of X-ray luminosity function from various surveys with ROSAT observatory (eg. Collins et al., 1997). Many of them indicate no negative evolution at the red-shift lower than 0.7, which is against the Einstein result.