Constraints on planetary and asteroid-mass primordial black holes from continuous gravitational-wave searches

TL;DR

This paper uses continuous gravitational-wave search data from LIGO/Virgo to set new, model-independent constraints on the abundance and merging rates of planetary and asteroid-mass primordial black holes, highlighting future detection prospects.

Contribution

It introduces a novel approach to constrain primordial black holes using continuous gravitational-wave signals, with minimal modeling assumptions and sensitivity estimates.

Findings

Sensitive to sources within about 10 parsecs for low-mass systems

Current results can constrain primordial black hole abundance

Future methods could improve constraints with full nonlinear frequency evolution

Abstract

We present new constraints on the merging rates of planetary-mass and asteroid-mass primordial black hole binaries using limits on continuous waves(quasi-monochromatic, quasi-infinite duration signals) derived from an all-sky search for isolated compact objects in the first six months of the third observing run (O3a) of LIGO/Virgo. We calculate the merging rates of these binaries in a model-independent way, and convert them to constraints on the primordial black hole abundance with minimal modelling assumptions. Our results show that we are sensitive to sources at most $\mathcal{O}(10$ pc) away for systems with chirp masses of $\mathcal{O}(10^{-5}M_\odot)$ at gravitational-wave frequencies around 30-40 Hz. These results also show that continuous-wave searches could in the future directly probe the existence of planetary-mass and asteroid-mass primordial black holes, especially those in binaries with asymmetric mass ratios. Furthermore, they demonstrate that new methods accounting for the full nonlinear gravitational-wave frequency evolution are needed to improve constraints on primordial black holes.