A mid-IR study of Hickson Compact Groups I : Probing the Effects of
  Environment in Galaxy Interactions
  Hickson Compact Groups (HCGs) are among the densest galaxy environments of
the local universe. To examine the effects of the environment on the infrared
properties of these systems, we present an analysis of Spitzer and ISO
mid-infrared imaging as well as deep ground based near-infrared imaging of 14
HCGs containing a total of 69 galaxies. Based on mid-infrared color diagnostics
we identify the galaxies which appear to host an active nucleus, while using a
suite of templates, we fit the complete infrared spectral energy distribution
for each group member. We compare our estimates of galaxy mass, star formation
rate, total infrared luminosities, and specific star formation rates (sSFR) for
our HCG sample, to samples of isolated galaxies and interacting pairs and find
that overall there is no discernible difference among them. However, HCGs which
can be considered as dynamically "old", host late-type galaxies with a slightly
lower sSFR than the one found in dynamically "young" groups. This could be
attributed to multiple past interactions among the galaxies in old groups, that
have led to the build up of their stellar mass. It is also consistent with our
prediction for the presence of diffuse cold dust in the intergalactic medium of
9 of the dynamically "old" groups.
