Large Molecular Gas Reservoirs in Star Forming Cluster Galaxies
  We present CO(2-1) observations of 72 galaxies in the nearby, disturbed
Antlia galaxy cluster with the Atacama Pathfinder Experiment (APEX) telescope.
The galaxies in our sample are selected to span a wide range of stellar masses
($10^{8}M_{\odot}\lesssim M_{\star} \lesssim 10^{10}M_{\odot}$) and star
formation rates
($0.0005M_{\odot}\text{yr}^{-1}<\text{SFR}<0.3M_{\odot}\text{yr}^{-1}$).
Reaching a depth of $23\text{mJy}$ in $50\text{km}\text{s}^{-1}$ channels, we
report a total CO detection rate of $37.5\%$ and a CO detection rate of $86\%$
for sources within 1 dex of the main sequence. We compare our sample with a
similar sample of galaxies in the field, finding that, for a fixed stellar mass
and SFR, galaxies in the Antlia cluster have comparable molecular gas
reservoirs to field galaxies. We find that $\sim41\%$ (11/27) of our CO
detections display non-Gaussian CO(2-1) emission line profiles, and a number of
these sources display evidence of quenching in their optical images. We also
find that the majority of our sample lie either just below, or far below the
main sequence of field galaxies, further hinting at potential ongoing
quenching. We conclude that the Antlia cluster represents an intermediate
environment between fields and dense clusters, where the gentler intracluster
medium (ICM) allows the cluster members to retain their reservoirs of molecular
gas, but in which the disturbed ICM is just beginning to influence the member
galaxies, resulting in high SFRs and possible ongoing quenching.
