Musings on primordial black holes: the formation and evolution of primordial black holes and binary primordial systems
Born in the first moments of the universe, primordial black holes (PBHs) could provide the answers to many of the biggest open questions in cosmology. How did the universe begin? What is dark matter made of? PBHs are one of the oldest candidates to explain the nature of dark matter (DM), and considered by many to be one of the leading candidates — DM may be nothing more than swarms of PBHs clustered in haloes around every galaxy, and even if PBHs only make up a sub-dominant component of DM, their possible existence still has great implications not only for the evolution of the Universe, but also its creation.  It is the aim of this project to improve constraints on the primordial universe, and to determine the origin of the black holes observed by LIGO-Virgo. To achieve this, I will perform studies fitting into 3 broad categories. Firstly, the formation of PBHs and binary systems in the early universe will be studied. The results will be used to determine an appropriate window function for use when calculating the PBH abundance - eliminating the largest source of uncertainty when calculating constraints on the primordial power spectrum from PBH constraints. Secondly, small-scale simulations will be used to determine the effect of PBHs on structure formation, which will be important for determining how external forces/objects might affect the evolution of binary PBH systems. Potentially, this may also lead to observable differences in the substructure of dark matter haloes between models with and without PBHs. Finally, the formation, evolution and possible disruption of systems containing 2 (or more) PBHs (or other compact objects) will be studied, making use of results from the previous sections.