Structural properties of faint low-surface-brightness galaxies

Abstract

We study the structural properties of Low-Surface-Brightness galaxies (LSB) using a sample of 263 galaxies observed by the Green Bank Telescope. We perform 2D decompositions of these galaxies in the Sloan Digital Sky Survey g, r, and i bands using the galfit software. Our decomposition reveals that about |$60\hbox{ per cent}$| of these galaxies are bulgeless i.e. their light distributions are well modelled by pure exponential discs. The rest of the galaxies were fitted with two components: a Sérsic bulge and an exponential disc. Most of these galaxies have bulge-to-total (B/T) ratio less than 0.1. However, of these 104 galaxies, |$20\hbox{ per cent}$| have B/T > 0.1 i.e. hosting significant bulge component and they are more prominent amongst the fainter LSBs. According to g−r colour criteria, most of the LSB galaxies in our sample are blue, with only 7 classified as red LSBs. About |$15\hbox{ per cent}$| of the LSB galaxies (including both blue and red) in our sample host stellar bars. The incidence of bars is more prominent in relatively massive blue LSB galaxies with very high gas fraction. These findings may provide important clues to the formation and evolution of LSB galaxies – in particular on the bar/bulge formation in faint LSB discs.