Elliptical Galaxy Dynamics: The Issues Pertaining to Galaxy Formation

Abstract

How elliptical galaxy dynamics relate to galaxy structure, stellar populations, spiral galaxies and environment are reviewed. The evidence assembled shows that most, if not all, galaxies originally classified as gE contain disks within them. Taken together, the existing evidence are most consistent with the gravitational, hierarchical, clustering, merging (HCM) concept that all galaxies, including gE, are formed from the combination of much smaller galaxies. Within the HCM picture, the evidence also strongly suggests that the subunits which go into forming galaxies must be related in specific ways both to the mass of the galaxy they will form, and to the environment in which the galaxy forms. Despite the extensive data that we now have on galaxies that can constrain their formation history, the lack of a physical understanding of the stellar initial mass function prevents us from developing realistic physical models for galaxy formation.