Abstract
Post-starburst galaxies, or E+A galaxies, are characterized by optical
spectra showing strong Balmer absorption lines, indicating a young stellar
population, and little or no emission lines, implying no active star formation.
These galaxies are interpreted as a transitional population between
star-forming, disk-dominated galaxies and spheroidal quiescent, non-star
forming galaxies. Here, we present single dish HI 21-cm emission line
measurements of a sample of eleven of these galaxies at redshifts z<0.05. We
detect H I emission in six of the E+A galaxies. In combination with earlier
studies, the total number of E+A galaxies with measured cold gas components is
now eleven. Roughly half of the E+As studied so far have detectable HI. The gas
fractions of these galaxies, measured with respect to their stellar mass, are
between 1 and 10 percent and are at the high end of the gas fractions measured
in gas-bearing early type galaxies and typically lower than seen in late-type
galaxies with comparable stellar masses. This finding is consistent with the
idea that E+As are currently evolving from the blue cloud to the red sequence.
However, the question of why the star formation has ceased in these galaxies
while a significant gas reservoir is still present can only be answered by
higher spatial resolution observations of the cold gas.
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