Production of Purely Gravitational Dark Matter

TL;DR

This paper investigates how purely gravitational interactions can produce the correct amount of dark matter in the universe, depending on inflation models and dark matter mass, highlighting the efficiency of gravitational production even at high masses.

Contribution

It provides a detailed analysis of gravitational particle production during inflation, demonstrating its effectiveness across a range of dark matter masses in a minimal setup.

Findings

Gravitational production can account for observed dark matter abundance.

Production remains efficient even when dark matter mass exceeds the Hubble scale.

The results depend on specific inflationary dynamics and dark matter mass.

Abstract

In the purely gravitational dark matter scenario, the dark matter particle does not have any interaction except for gravitational one. We study the gravitational particle production of dark matter particle in such a minimal setup and show that correct amount of dark matter can be produced depending on the inflation model and the dark matter mass. In particular, we carefully evaluate the particle production rate from the transition epoch to the inflaton oscillation epoch in a realistic inflation model and point out that the gravitational particle production is efficient even if dark matter mass is much larger than the Hubble scale during inflation as long as it is smaller than the inflaton mass.