The gravitational wave signal GW231123, associated with a record merger of black holes with a total mass of about 225 solar masses, may have been the result of a cosmic optical illusion rather than evidence of a violation of known astrophysical laws. This conclusion was reached by the authors of a study published in The Astrophysical Journal Letters, reports [Gizmodo](https://gizmodo.com/that-impossible-black-hole-merger-may-have-just-been-a-cosmic-optical-illusion-2000809879). Scientists suggest that gravitational waves may have undergone gravitational lensing — distortion caused by a massive object between the signal source and Earth. As a result, the event appeared much more massive than it actually was. "The observed large masses become understandable. Moreover, such an interpretation does not require assuming unusually high rotation speeds," noted co-author of the study, Srashti Goyal from the Albert Einstein Institute. Initially, astronomers were puzzled by the fact that the masses of the two merged black holes were estimated at 137 and 103 solar masses. Such values fall into the so-called "pair instability zone," where, according to current stellar evolution models, black holes should not form. According to the new model, lensing altered the characteristics of the recorded signal. Taking this effect into account, the mass of the black hole formed after the merger could be about 140 solar masses, rather than 225. In this case, the event would no longer contradict existing theories. Researchers believe that gravitational waves, like light, can experience lensing, diffraction, and interference effects. According to their calculations, such distortion could be created by a compact massive object within a larger gravitational field, such as a galaxy. At the same time, the authors emphasize that their work does not prove that such a scenario occurred in the case of GW231123. It is a plausible hypothesis that now needs to be tested with future observations. According to the scientists, if the existence of lensed gravitational waves is confirmed, it will open new opportunities for studying black holes, galaxies, and fundamental laws of physics.
