The Impact of Environment on the Evolution of HI in Galaxies
Galaxies in the local universe possess a wide range of shapes and sizes that have evolved over cosmic time. Processes from star formation and galaxy mergers to stellar and AGN feedback ultimately impact these galaxy properties. The neutral hydrogen gas content of a galaxy is an important tracer of the galaxy’s star formation potential and its morphology and can help distinguish the relative importance of different processes on galaxy evolution. I will discuss several studies in which we combined optical and HI 21 cm data (from SDSS and ALFALFA) in order to study the gas and stars in galaxies. In particular we examine how the gas content of galaxies evolves as a function of their location with respect to other galaxies. We study both pair interactions and the impact of groups and clusters on the gas content of galaxies. We find that interacting pairs show little change in their HI gas content as the interaction progresses while there is evidence for gas depletion towards the center of galaxy groups, and even more significantly towards the center of galaxy clusters, likely driven by ram pressure stripping. These results indicate that the group and cluster environments play a central role in the evolution of gas in galaxies in the local universe.