Constraining the Inflationary Equation of State

TL;DR

This paper investigates constraints on the inflationary equation of state parameter w, analyzing how observational limits and reheating conditions restrict possible deviations from the standard inflationary model.

Contribution

It provides new insights into how reheating temperature and energy scale constraints limit the inflationary equation of state, allowing for a broader range of models than previously considered.

Findings

w must be close to -1 for observable modes

Reheat temperature constrains w further

Possible acceleration epoch affects primordial power spectrum

Abstract

We explore possible constraints on the inflationary equation state: p=w\rho. While w must be close to -1 for those modes that contribute to the observed power spectrum, for those modes currently out of experimental reach, the constraints on w are much weaker, with only w<-1/3 as an a priori requirement. We find, however, that limits on the reheat temperature and the inflationary energy scale constrain w further, though there is still ample parameter space for a vastly different (accelerating) equation of state between the end of quasi-de Sitter inflation and the beginning of the radiation-dominated era. In the event that such an epoch of acceleration could be observed, we review the consequences for the primordial power spectrum.