Reconstructing Early Primordial Black Hole Domination from Gravitational-Wave Backgrounds
Abstract
Primordial Black Holes (PBHs) with masses below 𝒪(109)g occupy an interesting region of parameter space that is largely inaccessible to conventional observations. Despite evaporating before Big Bang Nucleosynthesis (BBN), these PBHs can naturally generate a period of early matter domination in the early Universe. A primordial gravitational-wave background (GWB) provides a window onto this otherwise inaccessible regime, since the modified expansion history leaves a characteristic spectral feature associated with the onset and end of PBH domination. The locations of these characteristic frequencies can be used to reconstruct the underlying PBH parameters, in particular the PBH mass. For a freely propagating GWB, the location of these frequencies additionally allow the initial PBH abundance to be determined. We derive simple numerical relations that map these characteristic frequencies directly onto the PBH mass and initial abundance. Future GW experiments span a vast frequency range, providing sensitivity to PBH masses from the BBN bound of 𝒪(109) g down to the lower bound of 𝒪(10) g. We find that the nanohertz signal reported by NANOGrav, if primordial in origin, is already probing PBH masses in the range $4−−90\,\mathrm{Mg}$. GW observations therefore offer access to a vast region of PBH parameter space that is otherwise beyond the reach of current experiments.
Related
- Third-order scalar induced gravitational waves during a matter-dominated era: secular growth and implications for primordial black hole domination
- Gravitational-wave signatures of primordial black hole clusters and the imprint of an early dense-core collapse
- Long-term 3+1 simulations of primordial black hole formation during radiation domination
- Gravitational waves flooding the Universe after wall domination
- Whispers of Supergravity in Gravitational Wave Backgrounds: Determining the Gravitino Mass from Cosmic Thermal History
BibTeX
@misc{delcorral2026reconstructing,
title = {{Reconstructing Early Primordial Black Hole Domination from Gravitational-Wave Backgrounds}},
author = {Daniel del-Corral and Angus Spalding},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.11891},
eprint = {2609.11891},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11891},
}
RIS
TY - UNPB
TI - Reconstructing Early Primordial Black Hole Domination from Gravitational-Wave Backgrounds
AU - Daniel del-Corral
AU - Angus Spalding
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2609.11891
UR - https://arxiv.org/abs/2609.11891
AB - Primordial Black Holes (PBHs) with masses below 𝒪(10^9)g occupy an interesting region of parameter space that is largely inaccessible to conventional observations. Despite evaporating before Big Bang Nucleosynthesis (BBN), these PBHs can naturally generate a period of early matter domination in the early Universe. A primordial gravitational-wave background (GWB) provides a window onto this otherwise inaccessible regime, since the modified expansion history leaves a characteristic spectral feature associated with the onset and end of PBH domination. The locations of these characteristic frequencies can be used to reconstruct the underlying PBH parameters, in particular the PBH mass. For a freely propagating GWB, the location of these frequencies additionally allow the initial PBH abundance to be determined. We derive simple numerical relations that map these characteristic frequencies directly onto the PBH mass and initial abundance. Future GW experiments span a vast frequency range, providing sensitivity to PBH masses from the BBN bound of 𝒪(10^9) g down to the lower bound of 𝒪(10) g. We find that the nanohertz signal reported by NANOGrav, if primordial in origin, is already probing PBH masses in the range $4−−90\,\mathrm{Mg}$. GW observations therefore offer access to a vast region of PBH parameter space that is otherwise beyond the reach of current experiments.
ER -