2026/05/06 by The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration +1832
#astro-ph.HE #astro-ph.CO
We report on a gravitational wave search for compact binary coalescences involving at least one component with mass between 0.2 M_\odot to 1 M_\odot, and ratio of component masses between 0.1 and 1. The analysis uses data collected by the LIGO detectors between May 24 2023 15:00 UTC and January 16 2024 16:00 UTC. No statistically significant sub-solar mass candidates were identified by the participating search algorithms. We report the detection sensitivity of the current searches to the target sub-solar mass black hole population. With the absence of detections, we place upper limits on the merger rate of sub-solar mass black holes, ranging from 110 \rm Gpc-3 yr-1 to 10000 \rm Gpc-3 yr-1 at 90% confidence. We constrain two illustrative dark matter scenarios that can form sub-solar mass compact objects with these searches: primordial black holes, and dark black holes forming in a dissipative dark matter model. For late-forming primordial black hole binaries, our search excludes the fraction of dark matter in primordial black holes to be ≤ 1 only for masses above 0.9 M_\odot. In the early-formation scenario, we limit this fraction to be ≤ 7% at 1 M_\odot, and ≤ 40%a at 0.35 M_\odot. For the dissipative model, the excluded region in the parameter space of dark matter fraction in dark black holes and their minimum possible mass extends down to (0.9 to 1.2) × 10-5 at 1 M_\odot with no constraints below 0.02 M_\odot. For the first time, we report the detection sensitivity of our searches to binaries with sub-solar mass neutron stars, and place the 90% confidence merger rate limit at (570 to 710) \rm Gpc-3 yr-1 for a population with component masses distributed uniformly down to 0.5 M_\odot.