Metallicity of Low Surface Brightness Galaxies

Low surface brightness galaxies (LSBGs) are an idiosyncratic population: blue colors, low metallicity, low stellar and gas surface density, low dust content, and high gas-to-star mass ratio. Allegedly having low star formation activity due to low gas surface density with relatively large gas reservoirs, LSBGs have very intriguing formation epochs and star formation histories (SFHs). Based on Ha photometry, near-infrared photometry and amount of neutral hydrogen, Kim (2007) show that LSBGs have ephemeral SFHs and suggest that LSBGs may experience late gas infall due to large specific angular momentum. Measuring both stellar and gas metallicity across disks can provide crucial information on how these LSB disks were formed and evolved. 8-m class telescopes, including Subaru, can nail down this issue.