Search for Gravitational Waves from the Coalescence of Subsolar-Mass Binaries in the First Half of Advanced LIGO and Virgo’s Third Observing Run
A. Nitz, Yifan Wang
Abstract
We present a search for gravitational waves from the coalescence of subsolar-mass black hole binaries using data from the first half of Advanced LIGO and Virgo's third observing run. The observation of a subsolar-mass black hole merger may be an indication of primordial origin; primordial black holes may contribute to the dark matter distribution. We search for black hole mergers where the primary mass is $0.1--7\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ and the secondary mass is $0.1--1\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$. A variety of models predict the production and coalescence of binaries containing primordial black holes; some involve dynamical assembly, which may allow for residual eccentricity to be observed. For component masses $>0.5\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$, we also search for sources in eccentric orbits, measured at a reference gravitational-wave frequency of 10 Hz, up to ${e}_{10}\ensuremath{\sim}0.3$. We find no convincing candidates and place new upper limits on the rate of primordial black hole mergers. The merger rate of 0.5--0.5 $(1.0--1.0)\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ sources is $<7100(1200)\text{ }\text{ }{\mathrm{Gpc}}^{\ensuremath{-}3}\text{ }{\mathrm{yr}}^{\ensuremath{-}1}$. Our limits are $\ensuremath{\sim}3--4$ times more constraining than prior analyses. Finally, we demonstrate how our limits can be used to constrain arbitrary models of the primordial black hole mass distribution and merger rate.