Where are the Nearby Gas-Rich LSB Galaxies?

Abstract

The Fisher-Tully `10 Mpc Catalog of Late-Type Galaxies&#39; (FT, 1981) is remarkably complete. Despite the considerable effort that has been spent searching for and cataloging low surface brightness (LSB) galaxies, almost no new HI-rich galaxies have been added to the volume to which the FT observations were both sensitive (d < 10 (M_{HI}/10^{8.2} Msolar)^{5/12} Mpc) and intended to be complete (d < 10 Mpc). It has not yet been demonstrated by the new surveys that HI-rich LSB galaxies are not properly represented in this catalog of nearby galaxies. Although new optical surveys are discovering heretofore uncatalogued galaxies at greater distances than the depth of the FT Catalog, they do not alter the completeness of the FT Catalog for HI-rich LSB objects. Thus, unless the galaxy population of the local volume is atypical, there is at present no evidence for a significant, new population of gas-rich galaxies that has escaped recognition until now.