Probing Dark Matter Interactions Near Supermassive Black Holes

Dr. Stephen Meighen-Berger

Abstract: We explore astrophysical probes of dark matter interactions in the extreme environments surrounding supermassive black holes. First, we use ultra-high-energy cosmic rays accelerated near supermassive black holes: sufficiently strong DM–nucleon scattering would fragment heavy nuclei, preventing them from reaching the observed energies. Combining this effect with acceleration requirements, we constrain DM–proton interactions for dark matter masses between 100 keV and 1 GeV. We then consider stars orbiting Sagittarius A*, where elastic DM scattering with protons and electrons can alter their energy balance and luminosity. Using observations of these stars, we derive complementary constraints on DM–proton and DM–electron interactions over a broad range of masses and halo profiles. Together, these probes demonstrate the potential of supermassive black-hole environments to constrain dark matter interactions beyond terrestrial and cosmological searches.