Dark matter component decaying after recombination: lensing constraints with Planck data

TL;DR

This paper tests a decaying dark matter model after recombination using Planck CMB data, finding strong lensing constraints but also that a small fraction of decaying dark matter improves fit to combined high- and low-redshift measurements.

Contribution

It provides the first comprehensive analysis of lensing constraints on decaying dark matter models post-recombination using Planck data.

Findings

Lensing constrains decaying dark matter fraction to less than 8%.

A 2-5% decaying dark matter fraction improves fit to combined data.

Lensing data significantly limits the parameter space of the model.

Abstract

It has been recently suggested~\cite{Berezhiani:2015yta} that emerging tension between cosmological parameter values derived in high-redshift (CMB anisotropy) and low-redshift (cluster counts, Hubble constant) measurements can be reconciled in a model which contains subdominant fraction of dark matter decaying after recombination. We check the model against the CMB Planck data. We find that lensing of the CMB anisotropies by the large-scale structure gives strong extra constraints on this model, limiting the fraction as $F<8\%$ at 2\,$\sigma$ confidence level. However, investigating the combined data set of CMB and conflicting low-$z$ measurements, we obtain that the model with $F\approx2\!-\!5$\% exhibits better fit (by 1.5-3\,$\sigma$ depending on the lensing priors) compared to that of the concordance $\Lambda$CDM cosmological model.