Gravitational Origin of Dark Matter

TL;DR

This paper proposes that dark matter is an inherent feature of gravity itself, specifically within the framework of bimetric gravity, which naturally includes a stable, gravitationally interacting massive spin-2 particle as a dark matter candidate.

Contribution

It introduces a novel dark matter candidate arising from bimetric gravity, linking dark matter properties directly to gravitational theory and its parameter space.

Findings

The massive spin-2 particle can be stable and heavy on cosmological scales.

Dark matter abundance can be explained via freeze-in production.

The model remains consistent with current gravity tests.

Abstract

Observational evidence for the existence of Dark Matter is limited to its gravitational effects. The extensive program for dedicated searches has yielded null results so far, challenging the most popular models. Here we propose that this is the case because the very existence of cold Dark Matter is a manifestation of gravity itself. The consistent bimetric theory of gravity, the only known ghost-free extension of General Relativity involving a massless and a massive spin-2 field, automatically contains a perfect Dark Matter candidate. We demonstrate that the massive spin-2 particle can be heavy, stable on cosmological scales, and that it interacts with matter only through a gravitational type of coupling. Remarkably, these features persist in the same region of parameter space where bimetric theory satisfies the current gravity tests. We show that the observed Dark Matter abundance can be generated via freeze-in and suggest possible particle physics and gravitational signatures of our bimetric Dark Matter model.