Spectrophotometry and Stellar Population Models of “E + A” Galaxies

Abstract

We present long-slit spectrophotometry of eight + galaxies which have been previously identified in the literature. We use a simple two-parameter modeling scheme to test if their stellar populations can be characterized uniquely by a decaying instantaneous starburst of well-determined age superposed upon a steady state galaxy substrate. Five of the objects are well characterized by burst-plus-elliptical galaxy models; two others are best fit by burst-plus-spiral galaxy models. One object cannot be described by such models, but it does resemble the spectra of some nearby merging galaxies with E + A-like spectra, possibly suggesting a multiple-burst scenario. Significant degeneracies, however, combined with the finite signal-to-noise of the data, severely limit the effectiveness of using optical spectral energy distributions alone to constrain the ages and mass fractions of the starburst components. The interpretation of E + A galaxies, especially at high redshift, must be approached cautiously.