Decoding the star forming properties of gas-rich galaxy pairs
  We extend the analysis of Bok et al. (2020) in which the HI content of
isolated galaxies from the AMIGA sample and selected paired galaxies from
ALFALFA were examined as a potential driver of galaxy location on the WISE
mid-infrared SFR-Mstar sequence. By further characterizing the isolated and
pair galaxy samples, i.e. in terms of optical galaxy morphology, a more
detailed and quantitative description of local galaxy environment by way of the
local number density (eta) and tidal strength (Q) parameters, star formation
efficiency (SFE(HI)), and HI integrated profile asymmetries, we present
plausible pathways for the broadening of the pair sample HI deficiency
distribution towards both high and low deficiencies compared to the narrower
isolated galaxy sample distribution (i.e. sigma_pairs = 0.34 versus sigma_AMIGA
= 0.28). We associate the gas-rich tail of the pair deficiency distribution
with the highest Q values, large profile asymmetries, and low SFEs. From this
we infer that merger activity is enhancing gas supplies, as well as disrupting
the efficiency of star formation, via strong gravitational torques. The
gas-poor wing of the deficiency distribution appears to be populated with
galaxies in denser environments (with larger eta values on average), more akin
to groups. Despite our gas-rich selection criterion, there is a small
population of early-type galaxies in the pair sample, which primarily fall in
the positive deficiency wing of the distribution. These results suggest that a
combination of a denser galaxy environment, early-type morphology, and higher
stellar mass, is contributing to the broadening of the deficiency distribution
towards larger deficiencies.
