Institute for Advanced Study / Princeton University Joint Astrophysics Colloquium

LIGO, Virgo, and KAGRA have recently announced the discovery of over 200 new compact binary mergers in low latency during their fourth observing run (O4), a majority of which are stellar-mass binary black hole mergers. The first segment of this run, designated O4a, has alone yielded 81 confirmed detections, significantly expanding the dataset available to probe the population properties of stellar-mass compact objects. In this talk I will highlight the key insights derived from the O4a gravitational-wave detections, and their impact on our understanding of the astrophysics of compact objects.