CMB constraints on Dark Matter models with large annihilation cross-section

TL;DR

This paper uses recent CMB data to constrain dark matter models with large annihilation cross-sections, especially those with Sommerfeld enhancement, and discusses future improvements with upcoming experiments.

Contribution

It provides new constraints on dark matter annihilation rates with large cross-sections using CMB measurements and forecasts the improved sensitivity of future CMB experiments.

Findings

WMAP data constrains DM annihilation rates with large cross-sections.

Upcoming Planck data will significantly tighten these constraints.

Large Sommerfeld-enhanced annihilation models are testable with CMB observations.

Abstract

The injection of secondary particles produced by Dark Matter (DM) annihilation around redshift 1000 would inevitably affect the process of recombination, leaving an imprint on Cosmic Microwave Background (CMB) anisotropies and polarization. We show that the most recent CMB measurements provided by the WMAP satellite mission place interesting constraints on DM self-annihilation rates, especially for models that exhibit a large Sommerfeld enhancement of the annihilation cross-section, as recently proposed to fit the PAMELA and ATIC results. Furthermore, we argue that upcoming CMB experiments such as Planck, will improve the constraints by at least one order of magnitude, thus providing a sensitive probe of the properties of DM particles.