Gemini Deep Deep Survey VI: Massive post-starburst galaxies at z=1

Preprint
Publisher Website
Google Scholar
  • 17 March 2005
Abstract
We show that there has been a dramatic decline in the abundance of massive post-starburst galaxies from z=1.2 to the present. Combining data from the Gemini Deep Deep and the Sloan Digital Sky Surveys to make mass-matched samples (M*>=10^10.2 Msun), we find that the fraction of galaxies in a post-starburst phase, identified by their strong Hdelta absorption lines, has decreased from about 50% at z=1.2 to a few percent today. This trend originates from a (1+z)^{2.5 \pm 0.7} evolution in the distribution of Hdelta equivalent widths for massive galaxies. With few exceptions, the local and the distant massive post-starburst galaxies have high visual extinction and young luminosity-weighted ages. Spectral synthesis studies of the high-redshift population using the PEGASE code, treating HdeltaA, EW[OII], Dn4000, and rest-frame colors, favor models in which these massive Hdelta-strong systems reveal the echoes of intense episodes of star-formation that faded ~1 Gyr prior to the epoch of observation on time-scales shorter than a few hundred million years. The z=1.4-2 epoch appears to be a time at which massive galaxies transition from a mode of sustained star formation to a quiet mode with weak and rare star-formation episodes. We argue that the most likely local counterparts for the distant massive post-starburst galaxies are passively evolving massive galaxies in the field and small groups.

This publication has 0 references indexed in Scilit: