Analyzing the Gravitational Lensing performance of SuperBIT to constrain Dark Matter Self Interactions

Abstract

Cold Dark Matter (CDM) faces several challenges at small scales ($\sim$ 1 Mpc) due to inconsistencies between predicted and observed properties of dark matter halos. Self-Interacting Dark Matter (SIDM) is a model of dark matter proposed to solve these discrepancies. SIDM particles can collide with each other through a self interaction cross-section $\sigma_{\text{DM}}$, and distribute energy in a way that can suppress small-scale structure formation. Interacting galaxy clusters are fascinating environments to investigate the presence of SIDM, since dark matter self-interactions would be abundant there. By mapping the location of dark matter in a cluster through gravitational lensing, and studying the lag between the luminous matter and dark matter, we can obtain upper bounds on $\sigma_{\text{DM}}$ up to some precision which depends on our lensing map, among other factors. The Superpressure Balloon-borne Imaging Telescope (SuperBIT) is an upcoming telescope that will be capable of taking diffraction-limited images over a $0.4 \degree \times 0.25 \degree$ field of view and six photometric bands between near-IR and near-UV wavelengths. In this thesis, we study the effects of SuperBIT's imaging capabilities on its lensing performance--- specifically the precision with which it can calculate DM position in a piece of infalling cluster substructure. We then estimate the precision with which SuperBIT data can constrain DM self-interaction. Our calculations show that SuperBIT can outperform HST constraints of 0.47 cm$^2$/g using about 95 cluster observations at a background galaxy density of about 51 arcmin$^{-2}$.