Do variations in the initial mass function affect galaxy evolution?

Sammanfattning: The initial mass function (IMF) describes the stellar mass distribution for a population of stars at birth. This parameter represents a topic of long standing discussion within astronomy due to its apparent insensitive nature to environmental conditions. However, in the last decade, significant evidence suggesting the contrary has been presented. Due to the role of the IMF as an input variable for a myriad of astronomical studies, its functional form is expected to influence the understanding within many topics of astronomy. In this thesis, we expand the research within the field of IMF variations as well as galaxy formation, adopting a heuristic approach in order to investigate the impact potential IMF variations might have on the formation and evolution of dwarf galaxies. We consider two distinct models for variation, motivated by either empirical results or theoretical arguments. Both the models result in the over-production of massive stars for low-metallicity environments. It is important to probe the most extreme environments for such a study, since it is there star formation could be very different. To this end, we consider the ultra faint dwarf galaxies in this work, which represent the extreme lower limit of the galaxy formation process, thus representing prime laboratories for studies of IMF variations. Their evolution over a period of 13.8 Gyr is modelled using state-of-the-art cosmological N-body + hydrodynamical simulations that feature zoomed in galaxy formation as well as a sophisticated recipe for feedback. It is found that IMF variations can dramatically impact the stellar mass growth history of dwarf galaxies, allowing for up to a 2 dex reduction in final stellar mass. In addition, all of the simulations considered are fully compatible with observational data of galaxy sizes, velocity dispersions, V-band magnitudes and metallicity. Thus, it is demonstrated in this work, for the first time, that IMF variations can represent a channel for the formation of the least massive galaxies to ever exist with a realistic enrichment.