Stochastic Gravitational Waves from Particle Origin

TL;DR

This paper explores the potential for a significant stochastic gravitational wave background originating from particle decay processes in the early universe, which could impact dark radiation and be detectable by future CMB experiments.

Contribution

It introduces a novel mechanism for gravitational wave production from inflaton decay, highlighting its possible dominance at high frequencies and implications for dark radiation detection.

Findings

Gravitational waves from particle decay could significantly contribute to dark radiation.

The spectrum peaks at high frequencies, beyond current experimental sensitivities.

Future CMB experiments could detect deviations in neutrino-like radiation from this source.

Abstract

We propose that there may be a substantial stochastic gravitational wave background from particle origin, mainly from the gravitational three-body decay of the inflaton. The emitted gravitons could constitute a sizable contribution to dark radiation if the mass of inflaton is close to the Planck scale, which can be probed by future CMB experiments that have a sensitivity on the deviation of the effective number of neutrinos in the standard cosmology, $\delta N_{\textrm{eff}}\sim 0.02 - 0.03$. We have also illustrated the spectrum of the radiated gravitational waves, in comparison to the current and future experiments, and found that gravitational waves from particle origin could be the dominant contribution to the energy density at high-frequency domain, but beyond the sensitivity regions of various experiments.