Properties of Low Surface Brightness Galaxies and Normal Spirals in the Near-Infrared

Abstract

We present results for J and Ks near-IR imaging data on a large sample of 88 galaxies drawn from the catalog of Impey et al. The galaxies span a wide range in optical and IR surface brightness and morphology (although they were drawn from a catalog constructed to identify low surface brightness galaxies [LSBGs]). They were also selected to include very low and high Hi mass galaxies in order to ensure that they span a wide range of evolutionary states. The near-IR data unveil many features of LSBGs not seen before in the optical. First, a high fraction of the observed LSBGs are very luminous in the near-IR, indicating that they have a well-developed old stellar population and that older LSBGs are more frequent in the universe than data from optical bands suggested. Second, the near-IR morphologies are often quite different than those seen in the optical. Many diffuse LSBGs that are apparently bulgeless when observed in blue bands instead exhibit nuclei in J and Ks bands. Third, we find significant trends between the near-IR morphologies of the galaxies and their ratio of H i mass to near-IR luminosity. Fourth, we find no trend in disk surface brightness with absolute magnitude but significant correlations when the bulge surface brightness is used. Finally, we find that the formation of a bulge requires a galaxy to have a total baryonic mass above � 10 10 M� . A wide variety of other correlations are explored for the sample. We consider correlations among morphologies, surface brightnesses, near-IR colors, absolute magnitudes, and H i masses. In addition, using previous results by Bell & de Jong, we convert the galaxies’ near-IR luminosities to stellar masses on the basis of color-dependent stellar mass-to-light ratios. This allows us to consider correlations among more fundamental physical quantities, such as the H i mass, the stellar mass, the total baryonic mass, the gas mass fraction, the mass surface density,