The Diverse Properties of the Most Ultraviolet‐Luminous Galaxies Discovered by GALEX

We report on the properties of a sample of ultraviolet luminous galaxies(UVLGs) selected by matching the Galaxy Evolution Explorer (GALEX) Surveys withthe Sloan Digital Sky Survey Third Data Release. Out of 25362 galaxies between0.02x10^10 L_solar at1530 Angstroms (observed wavelength). The properties of this population arewell correlated with ultraviolet surface brightness. We find that the galaxieswith low UV surface brightness are primarily large spiral systems with amixture of old and young stellar populations, while the high surface brightnessgalaxies consist primarily of compact starburst systems. In terms of thebehavior of surface brightness with luminosity, size with luminosity, themass-metallicity relation, and other parameters, the compact UVLGs clearlydepart from the trends established by the full sample of galaxies. The subsetof compact UVLGs with the highest surface brightness (``supercompact UVLGs'')have characteristics that are remarkably similar to Lyman Break Galaxies athigher redshift. They are much more luminous than typical localultraviolet-bright starburst galaxies and blue compact dwarf galaxies. Theyhave metallicities that are systematically lower than normal galaxies of thesame stellar mass, indicating that they are less chemically evolved. In allthese respects, they are the best local analogs for Lyman Break Galaxies.Comment: Fixed error in ObjID column of Table 1. 30 pages, 12 figures. Accepted for the GALEX special issue of ApJS. Abstract abridge