An H I Selected Sample of Galaxies

Abstract

Results from the Arecibo H I Strip Survey, an unbiased extragalactic H I survey, combined with optical and 21 cm follow-up observations, determine the H I mass function and the cosmological mass density of H I at the present epoch. Both are consistent with earlier estimates, computed for the population of optically selected galaxies. This consistency occurs because, although the distribution of optical central surface brightnesses among galaxies is flat, we fail to find a population of galaxies with central surface brightnesses fainter than 24 B-mag arcsec-2, even though there is no observational selection against them. Show more