Constraining Decaying Dark Matter

TL;DR

This paper investigates decaying dark matter models by modifying cosmological tools to compare predictions with observations, constraining decay parameters through CMB and structure formation data.

Contribution

It introduces a systematic approach to model and constrain decaying dark matter using modified CMB calculations and MCMC analysis.

Findings

Free streaming length constraint: λ_FS ≲ 0.5 Mpc for nonrelativistic decay.

Relativistic decay constraint: ((M_DDM/keV) Y)^2 (T_d/yr) ≲ 5×10^{-5}.

Updated bounds improve understanding of dark matter decay properties.

Abstract

We revisited the decaying dark matter (DDM) model, in which one collisionless particle decays early into two collisionless particles, that are potentially dark matter particles today. The effect of DDM will be manifested in the cosmic microwave background (CMB) and structure formation. With a systematic modification of CMB calculation tool \texttt{camb}, we can numerically calculated this effect, and compare it to observations. Further Markov Chain Monte Carlo \texttt{cosmomc} runnings update the constraints in that model: the free streaming length $\lambda_{FS}\lesssim0.5$Mpc for nonrelativistic decay, and $((M_{DDM}/keV) Y)^2 (T_d/yr)\lesssim5\times10^{-5}$ for relativistic decay.