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12th of April 2023
ATNF Colloquium
Resolved neutral atomic hydrogen (HI) gas studies to reveal the impact of intrinsic and environmental processes on local galaxies
Chandrashekar Murugeshan (CSIRO)
Abstract: Neutral atomic Hydrogen (HI) gas is the fundamental reservoir from which stars in galaxies are eventually formed. As such, studying the HI gas properties in galaxies give us important insights into how star formation proceeds. In addition, the HI gas is affected by internal mechanisms/processes such as angular momentum (AM), star formation/AGN feedback, disk instabilities, as well as non-axisymmetric potentials such as bars. On the other hand, the HI gas is also sensitive to (external) environmental processes such as tidal and ram-pressure stripping. Disentangling the degree of influence of these processes on the HI gas is paramount. In this talk I will show the importance of resolved HI studies in decoding the effects of both internal and external processes on galaxy evolution. By virtue of the extended nature of the HI disks in galaxies, one can derive rotation curves out to many times their optical radii, making high-resolution HI studies very important for tracing the total AM in galaxies. I will present the AM – Mass relation for local galaxies which is fundamental for constraining our cosmological models. In addition, I will talk about the connection between AM, disk stability and HI gas fraction in galaxies. Drawing from the results of a new HI survey of ring galaxies, I will also highlight the effects of bars in redistributing the HI gas and star formation in galaxies. Finally, I will present some new data is being delivered by the ASKAP WALLABY HI survey and the impact this is likely to have on HI and AM studies of galaxies in the local Universe as we venture into the SKA era.

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