Prospects of determination of reheating temperature after inflation by DECIGO

TL;DR

This paper explores how future space-based gravitational wave detectors like DECIGO could measure the reheating temperature after inflation if the tensor-to-scalar ratio is large, providing insights into the early universe's thermal history.

Contribution

It demonstrates the potential of upgraded DECIGO detectors to determine the reheating temperature within specific ranges, linking gravitational wave observations to inflation models.

Findings

DECIGO can measure $T_R$ if it lies between $6\times 10^6$ and $5\times 10^7$ GeV.

Upgraded DECIGO can determine $T_R$ in the range $3\times 10^7$ to $2\times 10^8$ GeV.

The measurement ranges are compatible with some inflation model predictions.

Abstract

If the tensor-to-scalar ratio $r$ of cosmological perturbations takes a large value $r\sim 0.1$, which may be inferred by recent BICEP2 result, we can hope to determine thermal history, in particular, the reheating temperature, $T_R$, after inflation by space-based laser interferometers. It is shown that upgraded and upshifted versions of DECIGO may be able to determine $T_R$ if it lies in the range $6\times 10^6< T_R < 5\times 10^7$GeV and $3\times 10^7<T_R<2\times 10^8$GeV, respectively. Although these ranges include predictions of some currently plausible inflation models, since each specification can probe $T_R$ of at most a decade range, we should determine the specifications of DECIGO with full account of constraints on inflation models to be obtained by near-future observations of temperature anisotropy and B-model polarization of the cosmic microwave background radiation.