Variable Inflaton Equation of State and Reheating

TL;DR

This paper investigates how a time-dependent inflaton equation-of-state affects reheating after inflation, using numerical solutions of Boltzmann equations and exploring implications for primordial gravitational waves.

Contribution

It introduces a framework for analyzing a variable inflaton EoS during reheating with numerical Boltzmann equations and discusses potential microscopic origins and gravitational wave consequences.

Findings

Robustness of Boltzmann system under different EoS Ans"atze

Impact of EoS variability on reheating dynamics

Possible signatures in primordial gravitational waves

Abstract

We explore the consequences of a time-dependent inflaton Equation-of-State (EoS) parameter in the context of the post-inflationary perturbative Boltzmann reheating. In particular, we numerically solve the perturbative coupled system of Boltzmann equations involving the inflaton energy density, the radiation energy density and the related entropy density and temperature of the produced particle thermal bath. We exploit reasonable Ans\"atze for the EoS and discuss the robustness of the Boltzmann system. We also comment on the possible microscopic origin related to a time dependent inflaton potential, discussing the consequences on a preheating stage and the related (primordial) gravitational waves.