Full-Spectrum Analysis of Gravitational Wave Production from Inflation to Reheating

Fuente: arXiv
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Autores principales: Xu, Xun-Jie, Xu, Yong, Yin, Qiqin, Zhu, Junyu
Formato: Preprint
Publicado: 2025
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author Xu, Xun-Jie
Xu, Yong
Yin, Qiqin
Zhu, Junyu
author_facet Xu, Xun-Jie
Xu, Yong
Yin, Qiqin
Zhu, Junyu
contents In this work, we systematically study gravitational wave (GW) production during both the inflationary and post-inflationary epochs. While inflationary GWs can be readily derived from tensor perturbations during inflation, post-inflationary GWs arise from a variety of processes during reheating and require detailed treatment for quantitative analysis. We consider four distinct production channels: $(i)$ pure inflaton annihilation, $(ii)$ graviton bremsstrahlung from inflaton decay, $(iii)$ radiation-catalyzed inflaton-graviton conversion, and $(iv)$ scattering among fully thermalized radiation particles. For each channel, we solve the corresponding Boltzmann equation to obtain the GW spectrum and derive a simple yet accurate analytical expression for it. By employing a consistent treatment of all production channels, our analysis yields for the first time the full spectrum of GWs produced during the inflationary and post-inflationary epochs. We find that, while inflationary GWs dominate at low frequencies, post-inflationary processes generally produce high-frequency GWs with considerably high energy densities that may significantly exceed that of inflationary GWs.
format Preprint
id arxiv_https___arxiv_org_abs_2505_08868
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Full-Spectrum Analysis of Gravitational Wave Production from Inflation to Reheating
Xu, Xun-Jie
Xu, Yong
Yin, Qiqin
Zhu, Junyu
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
In this work, we systematically study gravitational wave (GW) production during both the inflationary and post-inflationary epochs. While inflationary GWs can be readily derived from tensor perturbations during inflation, post-inflationary GWs arise from a variety of processes during reheating and require detailed treatment for quantitative analysis. We consider four distinct production channels: $(i)$ pure inflaton annihilation, $(ii)$ graviton bremsstrahlung from inflaton decay, $(iii)$ radiation-catalyzed inflaton-graviton conversion, and $(iv)$ scattering among fully thermalized radiation particles. For each channel, we solve the corresponding Boltzmann equation to obtain the GW spectrum and derive a simple yet accurate analytical expression for it. By employing a consistent treatment of all production channels, our analysis yields for the first time the full spectrum of GWs produced during the inflationary and post-inflationary epochs. We find that, while inflationary GWs dominate at low frequencies, post-inflationary processes generally produce high-frequency GWs with considerably high energy densities that may significantly exceed that of inflationary GWs.
title Full-Spectrum Analysis of Gravitational Wave Production from Inflation to Reheating
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2505.08868