[Previous] | [Session 4] | [Next]
M. Loewenstein (NASA/GSFC)
Hierarchical theories of structure formation predict specific and universal relations between measurable quantities such as dark matter mass, gas mass density and temperature, and galaxy mass density and velocity dispersion in virialized systems. While these predictions are generally successful, there are significant discrepancies -- discrepancies that become more pronounced on mass scales approaching those of galaxy groups. In this contribution I critically examine the hypothesis that heating related to early-epoch star formation is primarily responsible for these departures; and alternatively, analyze whether non-homology in the dark matter properties or galaxy orbits may play the dominant role.