Are cluster ellipticals the products of mergers?

Abstract

The rates of evolution of galaxy morphologies in clusters are integrated within an analytical collision model where merger remnants have elliptical morphologies. Cluster and galaxy properties are set by cosmological spherical infall in an Omega = 1 universe, and once galaxies fall into the cluster, they are severely tidally stripped by the cluster potential. Mergers become efficient as galaxies rebound out of the cluster core. The local merger rate is constant in time. The precise shape of the morphology-density and morphology-radius relations for ellipticals is in fine agreement with the observational data, including the sharp increase in elliptical fraction found by Whitmore and Gilmore (1991) within the central 100 kpc of clusters.