  Analysing the quantified HI profile asymmetries of galaxies in different
environments, we explore not only the prevalence of asymmetry in HI profiles,
but also the possibility of using HI profile asymmetries to trace merger
activity. We construct close pair and isolated galaxy catalogues of HI profiles
from the Arecibo Legacy Fast ALFA (ALFALFA) survey, and using a simple HI flux
ratio, quantify and compare the profile asymmetries between the two catalogues.
In this way, we investigate the popular proposition that merger activity causes
HI 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 HI profile.

Astrophysics of Galaxies