Enhanced H i profile asymmetries in close galaxy pairs

Abstract

Analysing the quantified H I profile asymmetries of galaxies in different environments, we explore not only the prevalence of asymmetry in H I profiles, but also the possibility of using H I profile asymmetries to trace merger activity. We construct close pair and isolated galaxy catalogues of H I profiles from the Arecibo Legacy Fast ALFA (ALFALFA) survey, and using a simple H I flux ratio, quantify and compare the profile asymmetries between the two catalogues. In this way, we investigate the popular proposition that merger activity causes H I profiles to become asymmetric, and thereby probe the role of mergers in galaxy evolution. We find small but significant differences between the asymmetry distributions of the two samples, indicating that merger activity does indeed enhance asymmetry in the global H I profile.