``E+A'' Galaxies: Environment and Evolution

Ann I. Zabludoff

Published 1997-12-02Version 1

One important approach to the study of galaxy evolution is to identify those galaxies whose spectral and/or morphological characteristics suggest that they are in transition. For example, ``E+A'' galaxies, which have strong Balmer absorption lines and no significant [OII] emission, are generally interpreted as post-starburst galaxies in which the star formation ceased within the last Gyr. This transition between a star forming and non-star forming state is a critical link in any galaxy evolution model in which a blue, star forming disk galaxy evolves into a S0 or elliptical. Another possible evolutionary track is that the star formation in an ``E+A'' resumes at some later time, if enough gas remains in the galaxy after its starburst ends. Given this ambiguity, it is important to investigate (1) the environment's role in ``E+A'' evolution, (2) the stellar and gas morphologies of ``E+A''s, (3) the likely progenitors of ``E+A''s, and (4) how common the ``E+A'' phase is in the evolution of galaxies. This proceeding summarizes recent results from several inter-related projects designed to address these questions. These projects focus on a sample of 21 nearby ``E+A'' galaxies (0.05 < z < 0.15) drawn from the Las Campanas Redshift Survey. These studies include VLA and HST observations, in addition to comparisons of these data with galaxy-galaxy interaction simulations and stellar population synthesis models.