Scientists have found evidence that gravitational waves created by the spectacular collision of two black holes carry information from the region just beyond the event horizon of the newly formed black hole. If confirmed by future observations, the finding could open up a whole new avenue for studying the immediate environment of a black hole, without requiring direct observation.
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In the new study, the researchers analyzed an extremely strong gravitational wave signal, known as GW250114. They found a particularly weak feature in the data, called a “wave,” that had been predicted theoretically but had never been observed in real-world observations. According to their analysis, the signal contains information from regions extremely close to the event horizon, the boundary beyond which nothing—not even light—can escape the gravitational pull of a black hole.
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The results, published June 24 in the journal Nature, suggest that gravitational wave observatories may in the future enable astronomers to explore regions that have remained inaccessible since black holes were first predicted by Albert Einstein's theory of general relativity.
Although astronomers have managed to image the superheated material surrounding some supermassive black holes and have recorded dozens of black hole mergers via gravitational waves, the event horizon itself remains one of the most inaccessible regions of the Universe to directly study.
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Unlike light, gravitational waves are extremely weak ripples in space-time that are created when massive objects accelerate. As they propagate almost unaffected through the Universe, they carry valuable information about violent cosmic phenomena that would otherwise remain invisible to scientists. According to study co-author Sizheng Ma, a postdoctoral researcher at the Perimeter Institute for Theoretical Physics in Canada, the newly detected signal offers a rare opportunity to study what happens immediately after two black holes collide.
