Date of Award

Spring 2023

Project Type


Program or Major


Degree Name

Doctor of Philosophy

First Advisor

Chanda Prescod-Weinstein

Second Advisor

Per Berglund

Third Advisor

Francois Foucart


Our Universe is filled with an invisible substance, called dark matter, which dominates the ways in which structures like galaxies form. Ultralight axion (ULA) dark matter is a possible alternative to more common cold dark matter models. Self-interactions in ULA models are often discarded because they are constrained to be very small. However, in my research, I have found that including self-interactions in these models can have a significant impact on what we observe, even when the self-interaction is small. I simulate ULA dark matter with self-interactions and quantify how different phenomena, including isolated soliton oscillations, binary soliton collisions, tidal disruptions of solitons, and dynamical friction change when considering self-interactions. I also consider a multi-field scenario where independent axion-like particle fields have self-interactions and inter-field interactions. The novel phenomenology that one can see when allowing for self-interactions and multiple axion fields may later be useful for constraining these types of dark matter models.