A study of the H i and optical properties of Low Surface Brightness galaxies: spirals, dwarfs, and irregulars

Abstract

We present a study of the H i and optical properties of nearby (z ≤ 0.1) Low Surface Brightness galaxies (LSBGs). We started with a literature sample of ∼900 LSBGs and divided them into three morphological classes: spirals, irregulars, and dwarfs. Of these, we could use ∼490 LSBGs to study their H i and stellar masses, colours, and colour–magnitude diagrams, and local environment, compare them with normal, High Surface Brightness (HSB) galaxies and determine the differences between the three morphological classes. We found that LSB and HSB galaxies span a similar range in H i and stellar masses, and have a similar |$M_{\rm H\, \small {I}}$|/M⋆–M⋆ relationship. Among the LSBGs, as expected, the spirals have the highest average H i and stellar masses, both of about 109.8 M⊙. The LSGBs’ (g − r) integrated colour is nearly constant as function of H i mass for all classes. In the colour–magnitude diagram, the spirals are spread over the red and blue regions whereas the irregulars and dwarfs are confined to the blue region. The spirals also exhibit a steeper slope in the |$M_{\rm H\, \small {I}}$|/M⋆–M⋆ plane. Within their local environment, we confirmed that LSBGs are more isolated than HSB galaxies, and LSB spirals more isolated than irregulars and dwarfs. Kolmogorov–Smirnov statistical tests on the H i mass, stellar mass, and number of neighbours indicate that the spirals are a statistically different population from the dwarfs and irregulars. This suggests that the spirals may have different formation and H i evolution than the dwarfs and irregulars.