Dynamical evolution of clusters of galaxies

The authors review observational evidence for the dynamical evolution of clusters of galaxies obtained from Einstein X-ray data. They show that most clusters are probably not evolved systems and discuss several of these unevolved systems in terms of the effects of dynamical evolution. In particular, it is shown that the density of the X-ray gas in A 194 combined with the galaxies' velocities is insufficient to ram pressure strip spirals. Therefore its large percentage of S0's cannot be explained by the ram pressure stripping mechanism. The authors discuss the observations of the unevolved clusters A 1367 and Virgo where gaseous halos have been found around some of the early type galaxies and in Virgo they suggest that M87 may be the progenitor of a cD galaxy.