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 ofmerging 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(b) alpha M-b(0.57 +/- 0.05), with a scatter of similar to 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 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.