The dynamics, shapes and origins of elliptical galaxies

Abstract

Recent observational and theoretical work indicates that elliptical galaxies are not the oblate spheroidal objects frequently assumed, but triaxial ellipsoidal bodies. Their forms are in most cases determined less by rotation than by anisotropy in their velocity dispersion structures dating from their earliest formative period. Dissipationless theories of galaxy formation have little difficulty in explaining in a general way the existence of galaxies of this type, although many details remain to be satisfactorily worked out. The domination of the dynamics of ellipticals by residual velocity anisotropy rather than by rotation would seem to be harder to understand in the context of dissipative theories.