Gravitational Wave Production During Reheating: From the Inflaton to Primordial Black Holes

TL;DR

This paper presents a comprehensive analysis of gravitational wave production from primordial black holes during reheating, identifying three distinct spectral peaks and comparing predictions with detection prospects.

Contribution

It introduces the first complete coherent analysis of GW spectra from PBHs, combining multiple sources and identifying three characteristic peaks in the spectrum.

Findings

Three GW spectral peaks identified at kHz, GHz, and PHz frequencies.

Predicted GW amplitudes are similar across the three peaks.

Comparison with current and future GW detectors shows potential for detection.

Abstract

We calculate the gravitational waves (GWs) produced by primordial black holes (PBHs) in the presence of the inflaton condensate in the early Universe. Combining the GW production from the evaporation process, the gravitational scattering of the inflaton itself, and the density fluctuations due to the inhomogeneous distribution of PBHs, we propose for the first time a complete coherent analysis of the spectrum, revealing three peaks, one for each source. Three frequency ranges ($\sim$ kHz, GHz, and PHz, respectively) are expected, each giving rise to a similar GW peak amplitude $\Omega_{\rm GW}$. We also compare our predictions with current and future GWs detection experiments.