Gauge invariant metric perturbations during reheating

TL;DR

This paper investigates the behavior of gauge invariant metric fluctuations during the reheating phase after inflation, finding no amplification of super Hubble scale fluctuations in the studied model.

Contribution

It provides an analysis of super Hubble gauge invariant metric fluctuations during reheating for a massive scalar field with a quadratic potential, showing no amplification occurs.

Findings

No amplification of gauge invariant metric fluctuations during reheating

Super Hubble Sasaki-Mukhanov parameter oscillates with constant amplitude

Reheating does not enhance metric perturbations in the studied scenario

Abstract

The possible amplification of gauge invariant metric fluctuations in the infrared sector are very important during reheating stage of inflation. In this stage the inflaton oscillates arount the minimum of the scalar potential. The evolution for super Hubble scales gauge invariant metric fluctuations can be studied by means of the Bardeen parameter. For a massive scalar field with a quadratic potential for a nonzero cosmological constant. I find that (in the reheating regime and for super Hubble scales), the Sasaki-Mukhanov parameter oscillates with amplitude constant such that there is no amplification of $Q$ during reheating.