Evolution of Clusters of Galaxies II: Dependence on Initial Cluster Model

Abstract

We investigated the evolution of clusters of galaxies using self-consistent N-body simulations. We varied the initial model of galaxies and clusters, and studied the dependence of evolution on initial conditions. We found that the growth rate of the common halo depends only weakly on galaxy models. On the other hand, the growth rate depends strongly on cluster models. Initially the growth rate is higher for cluster models with higher central density. However, this high growth rate drops in a few crossing times of the cluster, and after several crossing times, roughly half of the total mass is in the common halo in all models we considered. In the central region of clusters density cusps with the profile ρ~ r^{-1.2} develops regardless of the models of clusters and galaxies. We also found that the galaxies evolved so as to satisfy the relation between the masses of galaxies m_{gx} and their velocity dispersion σ_{gx} expressed as m_{gx} \propto σ_{gx}^{3~4} for all galaxy models as a consequence of their dynamical evolution through galaxy-galaxy interactions. We discuss the relation between our result and the observed Faber-Jackson relation.