Super Heavy Dark Matter in light of BICEP2, Planck and Ultra High Energy Cosmic Rays Observations

TL;DR

This paper explores how measurements of the tensor-to-scalar ratio r from CMB polarization experiments can inform models of super-heavy dark matter created during inflation, and how cosmic ray data constrain their properties.

Contribution

It analyzes the connection between inflationary gravitational wave measurements and super-heavy dark matter models, incorporating recent observational constraints.

Findings

Current upper limit r ≤ 0.12 constrains super-heavy dark matter scenarios.

Future measurements of r could help identify or rule out certain dark matter models.

Ultra high energy cosmic ray data limit the lifetime of super-heavy dark matter particles.

Abstract

The announcement by BICEP2 of the detection of B-mode polarization consistent with primordial gravitational waves with a tensor-to-scalar ratio, $r=0.2^{+0.07}_{-0.05}$, challenged predictions from most inflationary models of a lower value for $r$. More recent results by Planck on polarized dust emission show that the observed tensor modes signal is compatible with pure foreground emission. A more significant constraint on $r$ was then obtained by a joint analysis of Planck, BICEP2 and Keck Array data showing an upper limit to the tensor to scalar ratio $r\le 0.12$, excluding the case $r=0$ with low statistical significance. Forthcoming measurements by BICEP3, the Keck Array, and other CMB polarization experiments, open the possibility for making the fundamental measurement of $r$. Here we discuss how $r$ sets the scale for models where the dark matter is created at the inflationary epoch, the generically called super-heavy dark matter models. We also consider the constraints on such scenarios given by recent data from ultrahigh energy cosmic ray observatories which set the limit on super-heavy dark matter particles lifetime. We discuss how super-heavy dark matter can be discovered by a precise measurement of $r$ combined with future observations of ultra high energy cosmic rays.