The Ly{alpha} Reference Sample (LARS). XVI.

Additionally, both Ly{alpha}-emitters and weak or non-emitters are distributed evenly along the HI parameter space of optically selected z=0 galaxies. Around 74% of the sample is undergoing galaxy interaction, this fraction is higher for Ly{alpha}-emitters (83% for galaxies with EW>=20{AA}) than for weak or non-emitters (70%). Nevertheless, galaxies identified as interacting have Ly{alpha} and HI properties statistically consistent with those of non-interacting galaxies.

Our results show that global HI properties (on scales >30kpc) have little direct impact on the Ly{alpha} output from galaxies. Instead, HI likely regulates Ly{alpha} emission on small scales: statistical comparisons of Ly{alpha} and high angular resolution 21cm observations are required to fully assess the role of HI in Ly{alpha} radiative transfer. While our study indicates that major and minor galaxy mergers could play a role in the emission of Ly{alpha} photons in the local Universe, especially for galaxies with high HI fractions, the line of sight that a system is observed through ultimately determines the Ly{alpha} observables.