Oral Presentation Astronomical Society of Australia Annual Scientific Meeting including HWWS 2013

Galaxies that Flash as they Crash (#75)

Michelle E. Cluver 1 , Philip N. Appleton 2 , Patrick Ogle 2 , Thomas H. Jarrett 3 , Jesper Rasmussen 4
  1. Australian Astronomical Observatory, North Ryde, NSW, Australia
  2. IPAC/Caltech, Pasadena, CA, USA
  3. Dept. of Astronomy, University of Cape Town, Cape Town, South Africa
  4. Dark Cosmology Centre, Copenhagen, Denmark

Compact Groups are dense environments where galaxies are strongly interacting and have been shown to experience accelerated evolution from late-types, with copious star-formation, to early-type disk systems. I will present recent results from a Spitzer Space Telescope mid-infrared spectroscopy study of a sample of 23 Hickson Compact Groups; here we find evidence for excess excited molecular hydrogen emission in galaxies nearing the red sequence (in mid-infrared colour and specific star formation). What mechanism is responsible for heating the H2 and is shock-excited molecular hydrogen an important clue to evolution in less dense environments?