An ensemble cluster has been formed from a data set comprising a complete magnitude-limited sample of 680 giant galaxies (M B < ∼ −19) in 8 low-redshift clusters, normalised by the velocity dispersions and virial radii for the early-type cluster populations. Distinct galaxy populations have been identified, including an infall population. A majority (50–70% or greater) of the infall population ...

We report Australia Telescope Compact Array (ATCA) radio-continuum and ROSAT PSPC X-ray observations of the region surrounding the peculiar galaxy pair ESO 295-IG022, lying at the centre of the poor cluster Abell S0102. We identify a radio galaxy coincident with the galaxy pair, with bipolar, bent radio jets appearing centred on the southern galaxy, and extending both to the south, for about 95...

Detailed 3-D numerical simulations of an elliptical galaxy orbiting in a gas-rich cluster of galaxies indicate that gas dynamic stripping is less efficient than the results from previous, simpler calculations (Takeda et al. 1984; Gaetz et al. 1987) implied. This result is consistent with X-ray data for cluster elliptical galaxies. Hydrodynamic torques and direct accretion of orbital angular mom...

Although cluster dwarf galaxies are often neglected due to their faintness, recent observations demonstrate that they are critical for understanding the physical processes behind galaxy and cluster formation. Dwarfs are the most common galaxy type and are particularly abundant in clusters. Recent observational results suggest that dwarfs in dense environments do not all form early in the univer...

In the local universe, most QSO absorption-lines seem to arise from gas in extended 100 kpc halos around spiral galaxies. We present evidence that at high redshift, at least some absorption lines come from diierent sources: the gas is associated not with spiral galaxy halos but with the intra-cluster medium of proto-galaxy clusters. This gas, which is neutral and lumpy, may form a true intra-cl...