Gravitational particle production in bouncing cosmologies

TL;DR

This paper proposes that gravitational particle production during a sudden phase transition in bouncing cosmologies can explain reheating, with results aligning well with observational data.

Contribution

It demonstrates that gravitational particle production in matter-ekpyrotic bouncing universes can account for reheating, a novel explanation for this process in bouncing cosmologies.

Findings

Reheating temperature matches cosmological observations

Gravitational production of massive particles is effective in bouncing scenarios

Sudden phase transition triggers particle production in contracting phase

Abstract

It is argued that the Universe reheating in bouncing cosmologies could be explained via gravitational particle production, as due to a sudden phase transition in the contracting regime. To this end, it is shown that gravitational production of massive particles conformally coupled with gravity in a matter-ekpyrotic bouncing Universe, where the sudden phase transition occurs in the contracting regime, yields a reheating temperature which is in good agreement with cosmological observations.