Comparing Satellite Orbits for Cold and Self-Interacting Dark Matter Models

Abstract

Dark matter substructure provides a powerful observable in differentiating between dark matter particle models. In this thesis, we study the pericenters and apocenters of the orbits of CDM and SIDM satellites falling into a Milky Way-sized host. In particular, we compare four cases: CDM without tidal stripping, CDM with tidal stripping, SIDM without RPe or tidal stripping, SIDM without RPe but with tidal stripping, and finally SIDM with both RPe and tidal stripping. Findings demonstrate that although the pericenter is determined primarily by initial parameters of the orbit (such as energy and circularity), the apocenter was greatly affected by friction and mass loss. Furthermore, results suggest that satellites with lower mass and higher concentration attain apocenters, and that tidal stripping and RPe serve to increase apocenters by making satellites smaller and more dense. When taken together, in this regime of parameters CDM displayed somewhat higher apocenters than SIDM, although RPe partially counteracted this effect. Results suggest that, depending on the SIDM regime, differences in apocenters could be used to differentiate CDM and SIDM satellites.