Smaller stellar disc scale lengths in rich environments
  We investigate the dependence of stellar disc scale lengths on environment
for a sample of Sloan Digital Sky Survey Data Release 7 galaxies with published
photometric bulge-disc decompositions. We compare disc scale lengths at fixed
bulge mass for galaxies in an isolated field environment to galaxies in X-ray
rich and X-ray poor groups. At low bulge mass, stellar disc scale lengths in
X-ray rich groups are smaller compared to discs in both X-ray poor groups and
in isolated field environments. This decrease in disc scale length is largely
independent of halo mass, though shows some dependence on group-centric
distance. We also find that stellar disc scale lengths are smaller in X-ray
rich environments for a subset of star-forming galaxies and for galaxies of
different morphological types. We note that disc scale lengths of low mass
galaxies are known to have large systematic uncertainties, however we focus on
differences between samples with the same measurement biases. Our results show
that stellar disc scale lengths depend on X-ray brightness, a tracer of IGM
density, suggesting a role for hydrodynamic processes such as ram-pressure
stripping and/or starvation.
