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JuniorTukkie November 2021
Natural and Agricultural Sciences
The MeerKAT radio telescope in the Karoo (Credit: South African Radio Astronomical Observatory)
Discovery of a rare gas-rich galaxy group with the MeerKAT telescope By Shilpa Ranchod Ms Shilpa Ranchod, who recently graduated with a master’s degree in physics from the University of Pretoria (UP) leads an international team that reports the discovery of a large, unusual group of galaxies with South Africa’s MeerKAT telescope. This result is a component of her MSc thesis, supervised by Prof Roger Deane. Her research is focused on understanding atomic hydrogen’s role in star-formation in the younger universe, and dense regions within it. To do this, she uses the 64-antenna MeerKAT telescope, the South African precursor to the Square Kilometre Array. The observations that led to this serendipitous discovery form part of the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Survey, a large collaboration of international scientists. The survey produces hundreds of terabytes of data, which are processed on the cloud computing facility hosted www.up.ac.za/physics
by the Inter-university Institute of DataIntensive Astronomy (IDIA), a partnership between the universities of Pretoria, Cape Town and the Western Cape. This galaxy group was identified through the detection of 21cm atomic hydrogen (HI) emission, an important component of galaxies and a key ingredient in star formation. Within galaxies, HI is diffuse and extends far beyond the extent of the stars, making HI a sensitive tracer for the dynamics of galaxy evolution, particularly how the group environment affects this. Twenty of these HI-rich galaxies were detected, and through HI spectral line
Shilpa Ranchod
observations were identified as a large galaxy group for the first time. Some of the member galaxies have disturbed morphologies, clearly influenced by the group environment. These include an interacting pair of galaxies that will potentially merge, and a ‘jellyfish galaxy’ exhibiting a long tidal tail. The results suggest that the group is rare and in the early stages of assembly due to a large number of HI-detected galaxies and its unsettled velocity distribution. This discovery will be published in the Monthly Notices of the Royal Astronomical Society journal.
