Domain Walls and Gravitational Waves after Thermal Inflation

TL;DR

This paper explores how gravitational waves generated by domain walls after thermal inflation can serve as observable signals, offering a new way to probe the thermal inflation period and the effects of QCD instantons in cosmology.

Contribution

It demonstrates that gravitational waves from domain wall dynamics can be detected and that QCD instanton effects can eliminate domain walls while producing observable gravitational waves.

Findings

Gravitational waves from domain walls are detectable by pulsar timing and space-based detectors.

QCD instanton effects can remove domain walls and generate observable gravitational waves.

Gravitational wave signals can serve as probes of thermal inflation and early universe physics.

Abstract

Thermal inflation is an attractive solution to the cosmological moduli problem. However, domain walls may be formed after thermal inflation and some mechanisms are needed to eliminate the domain wall before it dominates the Universe. We point out that gravitational waves produced by the dynamics of domain walls may be observed by the pulsar timing experiments and future space-borne gravitational wave detectors, which provides a probe into the period of thermal inflation. We also show that the QCD instanton effect can effectively eliminate the domain walls with producing observable amount of gravitational waves.