Effects of electrically charged dark matter on cosmic microwave background anisotropies

TL;DR

This paper investigates how charged dark matter particles (CHAMPs) influence cosmic microwave background anisotropies, incorporating kinetic re-coupling effects, and compares predictions with Planck data to constrain CHAMP properties.

Contribution

It introduces the first detailed modeling of CHAMP perturbations including kinetic re-coupling and compares these models with observational data to set new constraints on CHAMP characteristics.

Findings

CHAMPs lighter than 10^{11} GeV significantly affect CMB spectra.

The model constrains the lifetime of CHAMPs to be longer than the recombination epoch.

Results are applicable to millicharged particles with similar properties.

Abstract

We examine the possibility that dark matter consists of charged massive particles (CHAMPs) in view of the cosmic microwave background (CMB) anisotropies. The evolution of cosmological perturbations of CHAMP with other components is followed in a self-consistent manner, without assuming that CHAMP and baryons are tightly coupled. We incorporate for the first time the "kinetic re-coupling" of the Coulomb scattering, which is characteristic of heavy CHAMPs. By a direct comparison of the predicted CMB temperature/polarization auto-correlations in CHAMP models and the observed spectra in the Planck mission, we show that CHAMPs leave sizable effects on CMB spectra if they are lighter than $10^{11}\,{\rm GeV}$. Our result can be applicable to any CHAMP as long as its lifetime is much longer than the cosmic time at the recombination ($\sim 4 \times 10^{5}\, {\rm yr}$). An application to millicharged particles is also discussed.