Some post-starburst E+A galaxies are not truly post starburst
  Post-starburst E+A galaxies are believed to be systems in a rapid transition
between major merger starbursts and quiescent ellipticals. Their optical
spectrum is dominated by A-type stars, suggesting a significant starburst that
was quenched recently. While optical observations of post-starburst galaxies
suggest little ongoing star formation, they have been shown to host significant
molecular gas reservoirs. This led to the suggestion that gas consumption or
expulsion are not required to end the starburst, and that star formation is
suppressed by turbulent heating of the molecular gas. We present NOEMA
continuum and CO(1-0) observations of 15 post-starburst galaxies, and collect
CO measurements in post-starburst galaxies from the literature. Using archival
far-infrared observations, we show that the majority of these systems host
obscured star formation, with some showing far-infrared emission that is
comparable to those of luminous and ultraluminous infrared galaxies. Once
far-infrared star formation rates are used, these systems show similar
SFR-$M_{\mathrm{H_2}}$ and Kennicutt-Schmidt relations to those observed in
star-forming and starburst galaxies. In particular, there is no need to
hypothesize star formation quenching by processes other than the consumption of
molecular gas by star formation. The combination of optical, far-infrared, and
CO observations indicates that some regions within these galaxies have been
recently quenched, while others are still forming stars at a high rate. We find
little connection between the post-burst age of the optically-thin quenched
regions and the star formation rate in the obscured regions. All this calls
into question the traditional classification of E+A galaxies.
