WALLABY Pre-Pilot Survey: the effects of angular momentum and environment on the H I 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 H I, 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_b-M_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 ~0.10 ± 0.01 dex, consistent with previous works. We examine the relation between the atomic gas fraction, f_atm, and the integrated atomic disc stability parameter q (the f_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 H I gas. We find that a majority of the Eridanus galaxies are H I 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.