Search for gravitational waves from high-mass-ratio compact-binary mergers of stellar mass and sub-solar mass black holes

TL;DR

This study searches for gravitational waves from mergers of stellar mass and sub-solar mass black holes, aiming to detect primordial black holes and constrain their role in dark matter, but finds no signals and sets upper limits on merger rates.

Contribution

First search for gravitational waves from high-mass-ratio mergers involving stellar and sub-solar mass black holes, providing new upper limits and dark matter constraints.

Findings

No significant gravitational-wave candidates detected.

Placed upper limits on merger rates of $<1.2\times10^{6}$ and $<1.6\times10^{4}$ Gpc$^{-3}$ yr$^{-1}$.

Constraints on primordial black holes contributing to dark matter.

Abstract

We present the first search for gravitational waves from the coalescence of stellar mass and sub-solar mass black holes with masses between $20 - 100~\mathrm{M}_{\odot}$ and $0.01 - 1~\mathrm{M}_{\odot}~($10 - 10^3$~\mathrm{M}_{J})$, respectively. The observation of a single sub-solar mass black hole would establish the existence of primordial black holes and a possible component of dark matter. We search the $\sim 164$ days of public LIGO data from 2015-2017 when LIGO-Hanford and LIGO-Livingston were simultaneously observing. We find no significant candidate gravitational-wave signals. Using this non-detection, we place a $90\%$ upper limit on the rate of $30-0.01~\mathrm{M}_{\odot}$ and $30-0.1~\mathrm{M}_{\odot}$ mergers at $<1.2\times10^{6}$ and $<1.6\times10^{4} ~\mathrm{Gpc}^{-3} \mathrm{yr}^{-1}$, respectively. If we consider binary formation through direct gravitational-wave braking, this kind of merger would be exceedingly rare if only the lighter black hole were primordial in origin ($<10^{-4}~\mathrm{Gpc}^{-3}\mathrm{yr}^{-1}$). If both black holes are primordial in origin, we constrain the contribution of $1 (0.1)~\mathrm{M}_{\odot}$ black holes to dark matter to $< 0.3 (3)\%$.