Too small to fail: characterizing sub-solar mass black hole mergers with gravitational waves

TL;DR

This paper investigates the detectability and characterization of sub-solar mass black hole mergers using gravitational waves, demonstrating that current and future detectors can confidently identify and analyze such exotic objects, which could shed light on dark matter and early Universe physics.

Contribution

The study performs Bayesian analysis on simulated gravitational-wave signals to assess the measurability of sub-solar mass black holes with current and next-generation detectors.

Findings

LIGO/Virgo O4 can confidently identify sub-solar mass components

Events are well-localized and provide spin information

Future detectors will enable precise measurements and tighter constraints

Abstract

The detection of a sub-solar mass black hole could yield dramatic new insights into the nature of dark matter and early-Universe physics, as such objects lack a traditional astrophysical formation mechanism. Gravitational waves allow for the direct measurement of compact object masses during binary mergers, and we expect the gravitational-wave signal from a low-mass coalescence to remain within the LIGO frequency band for thousands of seconds. However, it is unclear whether one can confidently measure the properties of a sub-solar mass compact object and distinguish between a sub-solar mass black hole or other exotic objects. To this end, we perform Bayesian parameter estimation on simulated gravitational-wave signals from sub-solar mass black hole mergers to explore the measurability of their source properties. We find that the LIGO/Virgo detectors during the O4 observing run would be able to confidently identify sub-solar component masses at the threshold of detectability; these events would also be well-localized on the sky and may reveal some information on their binary spin geometry. Further, next-generation detectors such as Cosmic Explorer and the Einstein Telescope will allow for precision measurement of the properties of sub-solar mass mergers and tighter constraints on their compact-object nature.