Probing sub-GeV Dark Matter-Baryon Scattering with Cosmological Observables

TL;DR

This paper uses cosmological data from Planck and SDSS to set new limits on dark matter-baryon scattering cross sections across a range of velocities and masses, extending constraints down to MeV-scale dark matter.

Contribution

It introduces a model-independent analysis of dark matter-baryon scattering using cosmological observables, incorporating high-$ extit{l}$ polarization data and detailed thermal evolution.

Findings

New constraints on dark matter-baryon cross sections for velocities v^n.

Extended limits down to dark matter masses of about 1 MeV.

Demonstrated the complementarity of cosmological probes with direct detection.

Abstract

We derive new limits on the elastic scattering cross-section between baryons and dark matter using Cosmic Microwave Background data from the Planck satellite and measurements of the Lyman-alpha forest flux power spectrum from the Sloan Digital Sky Survey. Our analysis addresses generic cross sections of the form $\sigma\propto v^n$, where v is the dark matter-baryon relative velocity, allowing for constraints on the cross section independent of specific particle physics models. We include high-$\ell$ polarization data from Planck in our analysis, improving over previous constraints. We apply a more careful treatment of dark matter thermal evolution than previously done, allowing us to extend our constraints down to dark matter masses of $\sim$MeV. We show in this work that cosmological probes are complementary to current direct detection and astrophysical searches.