Theoretical Physics Seminar (Moritz Fischer)

Astrophysical simulations of non-gravitational dark matter interactions

Abstract: Astrophysical probes allow us to constrain non-gravitational dark matter (DM) interactions by studying their impact on the distribution of both DM and baryons. Being able to accurately model these interactions at low redshift can be crucial. A standard method is N-body simulations that incorporate the additional particle physics of the dark sector. I will highlight simulations of several systems and explain why they are interesting for constraining DM interactions. At the high mass-end, this includes merging galaxy clusters, and at low halo masses, ultra-faint dwarf galaxies that are driven into gravothermal collapse by DM self-interactions. The latter is promising to explain perturbers of strong gravitational lenses. Moreover, I will explain how self-interactions could impact the gravitational wave signal of black hole mergers. Beyond self-interactions, DM could interact non-gravitationally, e.g., with protons. I will show the first N-body/SPH simulations which include DM-baryon scattering at low redshift, and discuss the impact of the interactions on the evolution of DM halos. Overall, N-body simulations that include non-gravitational DM interactions open a door to a rich DM phenomenology and allow us to shed light on the nature of DM.