Evolution of Galaxies in Clusters

Abstract

In this paper I show recent results of our studies on the evolution of an isolated cluster of galaxies using N-body simulations. In Sensui, Funato & Makino (1999) only one initial cluster model are investigated. In the present study, we varied the initial model of galaxies and clusters, and studied the dependence of evolution on initial conditions. We found that the mass of galactic halos are stripped and a common halo develops for any cluster models. Using result of scattering experiments of two halo-halo encounters, we show that the growth rate of the common halo (and complimentarily decrease rate of average mass of galactic halos) can be explained as a result of stripping due to cumulative encounters between two galactic halos.We also found that the galaxies evolved so as to satisfy the relation between the masses of galaxies mgx and their velocity dispersion σgx expressed as mgx ∝ σ3∼4gx 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.