WALLABY Pre-Pilot Survey: The effects of angular momentum and
  environment on the HI gas and star formation properties of galaxies in the
  Eridanus supergroup
  We use high-resolution ASKAP observations of galaxies in the Eridanus
supergroup to study their HI, angular momentum and star formation properties,
as part of the WALLABY pre-pilot survey efforts. The Eridanus supergroup is
composed of three sub-groups in the process of merging to form a cluster. The
main focus of this study is the Eridanus (or NGC 1395) sub-group. The baryonic
specific angular momentum - baryonic mass ($j_{\mathrm{b}} - M_{\mathrm{b}}$)
relation for the Eridanus galaxies is observed to be an unbroken power law of
the form $j_{\mathrm{b}} \propto M_{\mathrm{b}}^{0.57 \pm 0.05}$, with a
scatter of $\sim 0.10 \pm 0.01$ dex, consistent with previous works. We examine
the relation between the atomic gas fraction, $f_{\mathrm{atm}}$, and the
integrated atomic disc stability parameter $q$ (the $f_{\mathrm{atm}} - q$
relation), and find that the Eridanus galaxies deviate significantly from the
relation owing to environmental processes such as tidal interactions and
ram-pressure affecting their HI gas. We find that a majority of the Eridanus
galaxies are HI deficient compared to normal star-forming galaxies in the
field. We also find that the star formation among the Eridanus galaxies may be
suppressed owing to their environment, thus hinting at significant levels of
pre-processing within the Eridanus sub-group, even before the galaxies have
entered a cluster-like environment.
