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From the nature of dark matter to the escape of hydrogen ionizing photons

PhD ceremony:J.G. Bremer, BSc
When:December 05, 2022
Supervisors:P. (Pratika) Dayal, Prof Dr, prof. dr. R.F. (Reynier) Peletier
Where:Academy building RUG
Faculty:Science and Engineering

Dark matter constitutes the majority of the mass in the universe and is a vital component of galaxies and their formation. The precise nature of dark matter is not fully established and is a key question in astrophysics. Within the current most widely accepted cosmological paradigm, dark matter is described as cold dark matter. Inconsistencies with observations on small scales have motivated the introduction of alternative types of dark matter. In this thesis, we explore warm dark matter as an alternative to cold dark matter and aim to constrain its particle mass. We then focus on the interstellar medium of galaxies to determine their escape fraction of Lyman continuum photons. This is a fundamental parameter of galaxies within the first billion years of the universe, as the emission of these photons drives the transition from a neutral to a highly ionized intergalactic medium, the epoch of reionization. We address questions such as: how is the escape fraction shaped by galaxy properties? What role does the escape mechanism play? What is the impact of binary stars on the escape fraction? To study these important astrophysical topics in this thesis we use DELPHI, a framework designed to model the formation of early galaxies.