Study: Black Hole Merger May Be an Illusion Caused by Spacetime Distortion

A new study suggests that an 'impossible' merger event between two supermassive black holes may not be as contrary to physical laws as previously thought. The research posits that the actual masses of the merging black holes were smaller than initially measured.

In November 2023, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected faint ripples in spacetime originating from a black hole merger. The signal, designated GW231123, baffled the scientific community because initial interpretations indicated a collision between a black hole of 140 solar masses and another of 100 solar masses.

These results posed a significant challenge, as existing stellar evolution models struggle to explain the formation of such massive black holes, especially considering their seemingly high rotation speeds. Scientists have been searching for formation mechanisms for such unusual binary black hole systems. This new research team proposes that the perceived large masses might be an illusion.

The core effect behind this perceived illusion is gravitational lensing. Predicted by Einstein's 1915 general theory of relativity, this phenomenon occurs when massive objects warp spacetime, bending the path of light from background sources. The research team argues that gravitational waves, similar to light, can also be deflected and amplified by massive objects. They suggest that the GW231123 signal was a spacetime ripple amplified and potentially split by a gravitational lens, making the black holes appear more massive than they are.

By constructing a mathematical model for gravitational lensing and applying it to the GW231123 signal, the research team found that the total mass of the merging system was 140 solar masses, rather than the initially estimated 240 solar masses. While the specific object acting as the lens has not yet been identified, the study demonstrates that gravitational wave astronomy can be used to study extreme cosmic phenomena.