Cosmological Constraints on Dark Matter Interactions with Ordinary Matter

TL;DR

This paper uses cosmological data to place new constraints on dark matter interactions with electrons and protons, complementing other detection methods and excluding large interaction cross sections across a wide mass range.

Contribution

It provides model-independent constraints on dark matter--ordinary matter interactions using diverse cosmological observations, mapping these onto specific dark matter models.

Findings

Constraints exclude large cross sections for a wide range of dark matter masses.

Cosmological data complement direct detection and astrophysical probes.

Results rule out certain interaction strengths inaccessible to terrestrial experiments.

Abstract

Dark matter interactions with electrons or protons during the early Universe leave imprints on the cosmic microwave background and the matter power spectrum, and can be probed through cosmological and astrophysical observations. These interactions lead to momentum and heat exchange between the ordinary and dark matter components, which in turn results in a transfer of pressure from the ordinary to the dark matter. We explore these interactions using a diverse suite of data: cosmic microwave background anisotropies, baryon acoustic oscillations, the Lyman-$\alpha$ forest, and the abundance of Milky-Way subhalos. We derive constraints using model-independent parameterizations of the dark matter--electron and dark matter--proton interaction cross sections and map these constraints onto concrete dark matter models. Our constraints are complementary to other probes of dark matter interactions with ordinary matter, such as direct detection, big bang nucleosynthesis, various astrophysical systems, and accelerator-based experiments. They exclude sufficiently large cross sections for a large range of dark matter masses, which cannot be accessed by direct-detection experiments due to the overburden from the Earth's atmosphere or crust.