Abstract
We perform an improved cosmic microwave background (CMB) analysis to search for dark matter–proton scattering with a momentum-transfer cross section of the form for and . In particular, we present a new and robust prescription for incorporating the relative bulk velocity between the dark matter and baryon fluids into the standard linear Boltzmann calculation. Using an iterative procedure, we self-consistently include the effects of the bulk velocities in a cosmology in which dark matter interacts with baryons. With this prescription, we derive CMB bounds on the cross section, excluding for and for at 95% confidence, for dark matter masses below 10 MeV. Furthermore, we investigate how these constraints change when only a subcomponent of dark matter is interacting. We show that Planck limits vanish if of dark matter is tightly coupled to baryons. We discuss the implications of our results for present and future cosmological observations.
2 More- Received 10 August 2018
DOI:https://doi.org/10.1103/PhysRevD.98.123506
© 2018 American Physical Society