Evolution and Environment of Early-Type Galaxies

Abstract

The properties of early-type galaxies drawn from the SDSS database depend weakly, but significantly, on environment. Objects in regions of lower density tend to have slightly lower luminosities, velocity dispersions, bluer colors, and to be less homogeneous than objects in denser cluster-like regions. The chemical abundances of early-type galaxies drawn from the SDSS database also depend weakly on environment. Since chemical abundances also evolve with redshift, the observed trends constrain how strongly the luminosity weighted age depends on environment, provided the low redshift population is simply a passively aged version of the more distant population. The constraint does not depend on the detailed properties of stellar population synthesis models.