News release

From: Springer Nature

Astronomy: Gravitational wave signal from a black hole collision

The identification of the wave component of the gravitational-wave signal produced from the collision between two black holes is presented in Nature this week. Observations of the binary black hole merger event called GW250114 provides information about the remnant black hole event horizon —the ‘point of no return’.

Understanding the physics that guide a black hole event horizon is difficult as most observations are indirect; gravitational waves, which are formed by the collision of two black holes, could offer a clearer picture. Previous research has suggested that direct waves, a type of gravitational wave that can characterize the behaviour of the remnant black hole, could be emitted during this process, but no observation has been recorded.

Sizheng Ma and colleagues analysed gravitational wave data from GW250114, a signal from the collision of two merging black holes, detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in January 2025. They observed a direct wave from the collision, which behaved like a dampened oscillation with a frequency linked to the horizon’s rotation and a decay rate related to its surface gravity.

Careful modelling of the direct wave can tell us the mass and spin rate of the remnant black hole, and the authors make a preliminary attempt with some simplifying assumptions. Future work will require more accurate waveform models and studies across multiple events to assess the robustness and universality of these signals.