An H I Census of Loose Groups of Galaxies

We present results from our Parkes Multibeam H I survey of 3 loose groups of galaxies that are analogous to the Local Group. This is a survey of groups containing only spiral galaxies with mean separations of a few hundred kpc, and total areas of approximately 1 Mpc2; groups similar to our own Local Group. We present a census of the H I-rich objects in these groups down to a 1σ MHI sensitivity ~7×105M⊙, as well as the detailed properties of these detections from follow-up Compact Array observations. We found 7 new H I-rich members in the 3 groups, all of which have stellar counterparts and are, therefore, typical dwarf galaxies. The ratio of low-mass to high-mass gas-rich galaxies in these groups is less than in the Local Group meaning that the “missing satellite” problem is not unique. No high-velocity cloud analogs were found in any of the groups. If HVCs in these groups are the same as in the Local Group, this implies that HVCs must be located within ~300-400 kpc of the Milky Way.