Probing spacetime with black hole mergersConfirmed

by Neil Lu (Australia National University)

Thursday Mar 26, 2026, 1:00 PM → 2:30 PM America/Toronto

PI/4-400 - Space Room (Perimeter Institute for Theoretical Physics)

The detection of gravitational waves from binary black hole mergers enables us to observe the behavior of spacetimes in the strong-field, highly dynamical regime. The LIGO–Virgo–KAGRA collaboration has now observed hundreds of such events, offering several exciting candidates with differing properties. In this talk I will discuss recent results using these gravitational wave observations to test general relativity and probe the spacetime near black holes. I will present the first confident detection of an overtone in the ringdown signal during the postmerger phase of the binary black hole signal. I will also discuss the “direct wave” signal, a recently proposed model for the merger portion of the waveform that depends on the physics close to the black hole horizon. Finally, I will present the first results from applying this model to real data, using it to analyze the loudest gravitational wave event ever detected.