Dr Virginia Kilborn (Swinburne University of Technology)

The Evolution of Galaxies in Groups: HI content and the relationship with X-ray emission - Dr Virginia Kilborn Colloquium

ATNF Marsfield Lecture Theatre

Abstract

We have recently completed a deep, blind HI survey of 16 nearby galaxy
groups, as part of the GEMS study. Importantly, we have deep ROSAT X-ray
images of each of the groups, which allows us to investigate the
relationship between X-ray (hot gas) emission, and the HI (cold gas)
emission. Half of the groups in our sample exhibit intra-group X-ray
emission, and half were either undetected in X-rays, or only the central
galaxy was detected. We find that while there is a general trend for those
groups with intra-group X-ray emission to contain less HI near their
centres, there are exceptions to this trend, and the HI content of the
groups is more heavily dependent on galaxy morphology. I will present the
HI mass functions for the groups, which for the first time show a stark
difference in the low-mass slope for galaxies that belong in groups, to
galaxies in the surrounding region. I will also discuss the existence of
HI deficient galaxies in groups, and present the most likely mechanisms
for these galaxies to lose their gas.