Galaxy Formation With Ultralight Bosonic Dark Matter

Abstract

Ultralight bosonic particles forming a coherent state are dark matter candidates with distinctive wave-like behaviour on the scale of dwarf galaxies and below. In this thesis, a new simulation technique for ultralight bosonic dark matter, also called fuzzy dark matter, is developed and applied in zoom-in simulations of dwarf galaxy halos. When gas and star formation are not included in the simulations, it is found that halos contain solitonic cores in their centers reproducing previous results in the literature. The cores exhibit strong quasi-normal oscillations, which are possibly testable by observations. The results are inconclusive regarding the long-term evolution of the core mass. It is shown that the Fourier spectrum of the entire halo is related to the velocity distribution in collisionless N-body simulations in a simple way, contributing to a better understanding of the empirically-found core-halo mass relation. When gas and star formation are included, it is found that the collapsing baryonic component heats up the inner halo region, resulting in more compact and massive cores. Their radial profiles are determined by the inner halo velocity and the external potential sourced by the baryon density. This finding has direct consequences for observational constraints on fuzzy dark matter which are so far based on radial density profiles from dark matter only simulations.