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16th of August 2021
WALLABY observations of the Eridanus supergroup
by B-Q For et al.
For et al. present observations of the Eridanus supergroup obtained with the Australian Square Kilometre Array Pathfinder (ASKAP) as part of the pre-pilot survey for the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). It has been known for many years that there are a lerge number of galaxies in this area: a re-analysis of the region using the optical 6dF Galaxy Survey revealed that there are 3 distinct groups, namely the NGC 1407 group, the NGC 1332 group and the Eridanus group. These groups also form part of the supergroup, which is defined as a group of groups that may eventually merge to form a cluster.

The total number of detected neutral hydrogen (HI) sources is 55, of which 12 are background galaxies not associated with the Eridanus supergroup. The presence of distorted HI morphology in all detected galaxies suggests ongoing tidal interactions within the subgroups. The Eridanus group has a large fraction of HI deficient galaxies as compared to previously studied galaxy groups, but these HI deficient galaxies are not found at the centre of the group. The image above shows integrated H i intensity map of individual sources in the Eridanus Supergroup and in the background. Sources of the Eridanus group, the NGC 1407 group, the NGC 1332 group and background galaxies are in red, blue, green and black, respectively. All sources are enlarged by a factor of 4.5 for clarity. The designated ID number for all 55 HI sources reported in the paper are labelled.

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