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An HI perspective on galaxies 2.5 billion years ago

PhD ceremony:Ms A.R. (Avanti) Gogate
When:March 21, 2022
Supervisors:prof. dr. M.A.W. (Marc) Verheijen, prof. dr. J.M. (Thijs) van der Hulst
Where:Academy building RUG
Faculty:Science and Engineering
An HI perspective on galaxies 2.5 billion years ago

Galaxies are believed to have formed and evolved within clumps of dark matter (known as dark matter halos) through the merging of smaller, less complex systems, as explained by one of the most popular cosmological models known as Lambda CDM (ΛCDM). Thus, the properties of galaxies are shaped by their genesis (nature) and the influence of the environments in which they reside (nurture). Synergizing our knowledge of stellar population studies with the gas content of galaxies provides a more complete picture of how galaxies we see today evolved over time. In particular, the atomic hydrogen content of galaxies (HI) is a vital ingredient in star formation and provides unparalleled insights into the role of gas and environment in galaxy evolution. Unfortunately, not much is known about the behaviour of HI over cosmic time due to limitations in telescope sensitivity for deep HI observations.

In this thesis, we presented the data and results of the Blind Ultra-Deep HI Environmental Survey (BUDHIES), which still provides some of the only blind observations of 166 galaxies detected over a range of cosmic environments at a redshift z~0.2 (~2.5 billion years in look-back time). this thesis also provides further insights into the time evolution of HI in galaxies using tools such as the HI mass function and the Tully-Fisher relation, along with the details on the data processing and optical counterpart identification with ancillary data. This thesis aims to provide a benchmark for next-generation HI surveys that will be able to overcome the limitations of current radio facilities.