Herschel observations of Hickson compact groups of galaxies: Unveiling
  the properties of cold dust
  We present a Herschel far-IR and sub-mm study of a sample of 120 galaxies in
28 Hickson Compact Groups. Fitting their UV to sub-mm spectral energy
distributions with the model of da Cunha et al. (2008), we accurately estimate
the dust masses, luminosities and temperatures of the individual galaxies. We
find that nearly half of the late-type galaxies in dynamically "old" groups,
those with more than 25% of early-type members and redder UV-optical colours,
have also significantly lower dust-to-stellar mass ratios compared to those of
actively star-forming galaxies of the same mass found both in HCGs and the
field. Examining their dust-to-gas mass ratios we conclude that dust was
stripped out of these systems as a result of the gravitational and hydrodynamic
interactions, experienced due to previous encounters with other group members.
About 40% of the early-type galaxies (mostly lenticulars), in dynamically "old"
groups, display dust properties similar to those of the UV-optical red
late-type galaxies. Given their stellar masses, star formation rates and
UV-optical colours, we suggest that red late-type and dusty lenticular galaxies
represent transition populations between blue star-forming disk galaxies and
quiescent early-type ellipticals. [...ABRIDGED...] Our deep Herschel
observations also allow us to detect the presence of diffuse cold intragroup
dust in 4 HCGs. We also find that the fraction of 250micron emission which is
located outside of the main bodies of the red late-type galaxies as well as of
the dusty lenticulars is 15-20% of their integrated emission at this band. All
these findings are consistent with an evolutionary scenario in which gas
dissipation, shocks and turbulence in addition to tidal interactions, shape the
evolution of galaxies in compact groups.
