Cosmic Microwave Background constraints of decaying dark matter particle properties

TL;DR

This paper uses cosmic microwave background data to constrain properties of decaying dark matter particles, specifically sterile neutrinos, by analyzing their effects on the universe's reionization history.

Contribution

It provides new bounds on the mass and lifetime of decaying dark matter particles based on WMAP 7-year data, focusing on sterile neutrino models.

Findings

Dark matter particle mass between 250 eV and 1 MeV.

Particle lifetime between 2.23×10^3 and 1.23×10^18 years.

Best fit parameters: 17.3 keV mass and 2.03×10^16 years lifetime.

Abstract

If a component of cosmological dark matter is made up of massive particles - such as sterile neutrinos - that decay with cosmological lifetime to emit photons, the reionization history of the universe would be affected, and cosmic microwave background anisotropies can be used to constrain such a decaying particle model of dark matter. The optical depth depends rather sensitively on the decaying dark matter particle mass m_{dm}, lifetime tau_{dm}, and the mass fraction of cold dark matter f that they account for in this model. Assuming that there are no other sources of reionization and using the WMAP 7-year data, we find that 250 eV < m_{dm} < 1 MeV, whereas 2.23*10^3 yr < tau_{dm} < 1.23*10^18 yr. The best fit values for m_{dm} and tau_{dm}/f are 17.3 keV and 2.03*10^16 yr respectively.