Dark matter from gravitational particle production at reheating

TL;DR

This paper proposes a mechanism where gravitational particle production during reheating creates dark matter from non-minimally coupled scalars, constraining their mass and coupling based on observed dark matter abundance.

Contribution

It introduces a novel dark matter production scenario via curvature-induced particle creation at reheating, linking particle properties to cosmological observations.

Findings

Dark matter can originate from gravitational particle production at reheating.

Constraints on spectator scalar mass and coupling are derived from dark matter abundance.

For quadratic inflation, a 0.1 GeV mass and coupling of about 1 fit observations.

Abstract

We show that curvature induced particle production at reheating generates adiabatic dark matter if there are non-minimally coupled spectator scalars weakly coupled to visible matter. The observed dark matter abundance implies an upper bound on spectator masses $m$ and non-minimal coupling values $\xi$. For example, assuming quadratic inflation, instant reheating and a single spectator scalar with only gravitational couplings, the observed dark matter abundance is obtained for $m\sim 0.1$ GeV and $\xi \sim 1$. Larger mass and coupling values of the spectator are excluded as they would lead to overproduction of dark matter.