  We present results from our multi-wavelength study of SG1120, a super galaxy
group at z=0.37, that will merge to form a galaxy cluster comparable in mass to
Coma. We have spectroscopically confirmed 174 members in the four X-ray
luminous groups that make up SG1120, and these groups have velocity dispersions
of sigma(1D)=303-580 km/s. We find that the supergroup has an excess of 24
micron members relative to CL1358+62, a rich galaxy cluster at z=0.33. SG1120
also has an increasing fraction of 24 micron members with decreasing local
galaxy density, i.e. an infrared-density relation, that is not observed in the
rich cluster. We detect nine of the group galaxies in VLA 1.4 Ghz imaging, and
comparison of the radio to total infrared luminosities indicates that about 30%
of these radio-detected members have AGN. The radio map also reveals that one
of the brightest group galaxies has radio jets. We are currently analysing the
1.4 Ghz observations to determine if AGN can significantly heat the intrahalo
medium and if AGN are related to the excess of 24 micron members.
