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Progenitors of heavy black holes from stellar evolution Ethan Robert John Winch (24292409) PUREID: 665187064 Astronomy astrophysics stellar evolution massive stars black holes MESA Massive stars are the progenitors of black holes such as those detected in gravitational wave (GW) observations. As such, understanding their formation has been a multi- disciplinary effort involving theory, computations and observations. With the detection of GW190521 providing the largest stellar mass black hole merger progenitors in the GW catalogues, many theories were discussed in order to test or verify the reasons behind these unexpectedly large objects. Furthermore, with the ever increasing sensitivity of modern GW detectors, the promise of more detectors such as the Laser Interferometer Space Antenna (LISA), and the expectation of observations from Pair Instability Supernovae and their progenitors with satellites such as the James Webb Space Telescope (JWST) and Euclid, it is important - now more than ever - to develop physically consistent systematic theoretical models of what the astronomical community can expect from these massive, and very massive stars. In this thesis, I systematically explore the massive and very massive star parameter space across a range of different initial conditions with the aim of providing a consistent set of predictions which can be used to validate theory in the presence of current and upcoming observations. This is achieved by running several grids of MESA models, and changing relevant stellar evolution parameters, to explore specifically the question of the Pair Instability boundary. Chapter 3 is the beginning of this research, which critically investigates a predominantly unexplored parameter space in the hydrogen-rich massive and very massive stars, based on the work of Vink et al. (2021). Chapter 4 follows this by expanding the parameter space into the low-metallicity, and rapid rotation regime. Chapter 5 finishes the study by constructing a grid of Helium stars across the same parameter space. Altogether, these chapters provide a comprehensive study of the progenitors of heavy stellar black holes which is aimed at providing insights into how the objects formed in observations such as GW events, or explaining the dearth of PISN candidates at the expected mass ranges through a theoretical lens. Chapters 1 and 2 provide the background, motivation and methodology for this study, including an in-depth look at the physical parameters studied and the MESA stellar evolution code. 2026-10-01T16:17:52Z Text Thesis 10.17034/32805155.v1 https://figshare.com/articles/thesis/Progenitors_of_heavy_black_holes_from_stellar_evolution/32805155 All Rights Reserved