Massive gravitons as dark matter and gravitational waves

TL;DR

This paper explores the idea that massive gravitons could serve as dark matter within bimetric gravity, linking their production to gravitational waves detectable by observatories like LIGO.

Contribution

It demonstrates that massive gravitons can behave as dark matter and discusses their production mechanism and associated gravitational wave signals in a bimetric gravity framework.

Findings

Massive gravitons act as dark matter fluid.

Production of massive gravitons is linked to gravitational wave generation.

Detection of gravitational waves could indicate the presence of massive gravitons as dark matter.

Abstract

We consider the possibility that the massive graviton is a viable candidate of dark matter in the context of bimetric gravity. We first derive the energy-momentum tensor of the massive graviton and show that it indeed behaves as that of dark matter fluid. We then discuss a production mechanism and the present abundance of massive gravitons as dark matter. Since the metric to which ordinary matter fields couple is a linear combination of the two mass eigenstates of bigravity, production of massive gravitons, i.e. the dark matter particles, is inevitably accompanied by generation of massless gravitons, i.e. the gravitational waves. Therefore, in this scenario some information about dark matter in our universe is encoded in gravitational waves. For instance, if LIGO detects gravitational waves generated by the preheating after inflation then the massive graviton with the mass of $\sim 0.01$ GeV is a candidate of the dark matter.