Intergalactic gas in groups of galaxies.

摘要

We present two studies of intergalactic gas in groups of galaxies. In the first we perform mosaicked radio interferometric HI observations of five groups of galaxies. We find a multitude of interactions and interesting HI morphologies in these systems. Intragroup HI, not easily associated with a single group member, is present in the three most spiral rich systems. An HI mass function (HIMF) compiled from these data, and an additional three groups, is consistent with other HI mass functions for the group environment in that it has a flat low mass slope. The flattening of the faint end slope of the H IMF suggests that physical processes in the group environment are responsible for removing gas from low mass galaxies.;In the second study we characterize the environments of six bent-double radio galaxies and use these sources to measure the density of the intergalactic gas which they are traveling through. These sources provide evidence that intragroup gas exists in groups of galaxies even when the intragroup medium is not X-ray bright. The densities derived from this method indicate that groups of galaxies and their surroundings are likely to contain significant reservoirs of baryons.;Uniting these two studies we consider the effects of ram pressure stripping on dwarf galaxies. We find the densities and velocities seen in groups to be sufficient, especially when coupled with tidal forces, to strip the H I from these systems and account for the flattening of the H IMF that is observed for the group environment.;Additionally, we examine the NGC 4065 group of galaxies and use X-ray observations and a bent-double radio source to probe the density of intergalactic gas in this group. We examine spiral group member UGC 07049 for evidence of ram pressure stripping and find that ram pressure alone is not strong enough to produce significant gas loss for this galaxy. A combination of tidal and ram pressure stripping may be strong enough and is likely in this environment.