Massive Galaxy Mergers Have Distinctive Global HI Profiles
  The global 21 cm HI emission-line profile of a galaxy encodes valuable
information on the spatial distribution and kinematics of the neutral atomic
gas. Galaxy interactions significantly influence the HI disk and imprint
observable features on the integrated HI line profile. In this work, we study
the neutral atomic gas properties of galaxy mergers selected from the Great
Observatories All-sky LIRG Survey. The HI spectra come from new observations
with the Five-hundred-meter Aperture Spherical Telescope and from a collection
of archival data. We quantify the HI profile of the mergers with a newly
developed method that uses the curve-of-growth of the line profile. Using a
control sample of non-merger galaxies carefully selected to match the stellar
mass of the merger sample, we show that mergers have a larger proportion of
single-peaked HI profiles, as well as a greater tendency for the HI central
velocity to deviate from the systemic optical velocity of the galaxy. By
contrast, the HI profiles of mergers are not significantly more asymmetric than
those of non-mergers.
