Evolution of clusters of galaxies: Mass stripping from galaxies and growthof common halos

We investigated the evolution of clusters of galaxies using self-consistent N-body simulations in which each galaxy was modeled by many particles. We carried out simulations for about 20 cases using different initial conditio ns. In all simulations, clusters were initially in virial equilibrium. We f ound that more than half of the total mass escaped from individual galaxies within a few crossing times of the cluster, and that a diffuse halo was fo rmed. The growth rate of the common halo depended on the size of individual galaxies only weakly. The stripping of the mass from galaxies was mainly d ue to the interaction of galaxies, not due to the effect of the tidal field of the cluster potential. The amount of stripped mass was larger for galax ies in the central region than for those in the outer region, since the int eractions were more frequent in the central region. As a result, a positive correlation between the distance from the center and the mass of the galax y developed. The volume-density profile of the common halo is expressed as p proportional to r(-1) in the central region. This mass distribution is co nsistent with the mass distribution in clusters estimated using X-ray obser vations.