Structure Formation and the Global 21-cm Signal in the Presence of Coulomb-like Dark Matter-Baryon Interactions

Understand

Many compelling dark matter (DM) scenarios feature Coulomb-like interactions between DM particles and baryons, in which the cross section for elastic scattering scales with relative particle velocity as $v^{-4}$.

• Previous studies have invoked such interactions to produce heat exchange between cold DM and baryons and alter the temperature evolution of hydrogen.
• In this study, we present a comprehensive study of the effects of Coulomb-like scattering on structure formation, in addition to the known effects on the thermal history of hydrogen.
• We find that interactions which significantly alter the temperature of hydrogen at Cosmic Dawn also dramatically suppress the formation of galaxies that source the Lyman-$\alpha$ background, further affecting the global 21-cm signal.