On the population of H I dwarf galaxies

Results are reported from a 21 cm survey of fields in the Perseus-Pisces supercluster and a foreground void, which was designed to find gas-rich dwarf galaxies or optically faint H I clouds with masses greater than 10 to the 8th solar masses. Sixteen objects have been detected in the supercluster, nine of them previously uncataloged. No objects were found in the void fields, an indication that H I dwarf galaxies follow the spatial structure defined by bright galaxies, although the results do not rule out a moderate 'bias' between dwarfs and bright galaxies. The number of galaxies detected is smaller than expected from a simple extrapolation of the optical luminosity function. These data leave no room for a substantial population of H I dwarfs or gas-rich, low surface brightness giants that could have been missed by conventional, optical galaxy catalogs. 24 refs