Title: Searching for sub-solar mass black hole binaries via GWs

Speaker: Dr. Bhooshan Gadre, Utrecht University

Abstract: The LIGO-Virgo-KAGRA (LVK) Collaboration has reported 90 candidates of gravitational wave events from compact binary coalescences (CBCs) comprising stellar mass black holes and neutron stars. Several of these detections still challenge our understanding of the astrophysics of stellar evolution and binary formation as contributions from secular and dynamical formation channels are unclear. I will briefly discuss exciting search results from the recently concluded third observing run (O3) of LIGO-Virgo detectors with a primary focus on sub-solar mass.

Detection of a sub-solar mass ultra-compact object in a merger would be groundbreaking, leading to new perspectives on the existence of alternative scenarios of black hole formation besides the classical theory of stellar evolution. But even the null detection of a sub-solar mass compact object during O3 allowed us to characterize the sensitivity of the search and set upper limits on the merger rate for binary containing such a black hole. Using the merger rates, we estimate the dark matter fraction made of primordial black holes and the upper bound of the fraction of dissipative dark matter that can be in back holes. Given the far-reaching implications of observing a sub-solar mass black hole, LVK will continue the search in the region while attempting to improve the sensitivity of the search pipelines further.