Scientists may have detected light from a violent merger of two black holes for the first time
Scientists seem to have detected a black hole merger like no other. A collision between the two black holes lit up the skies, capturing a moment that has so far been undetected, according to a new study. And they expect to spot more in the future. The discovery, if confirmed, could be the first to record a merger emitting light. Until now, scientists have detected them indirectly through gravitational waves, which are often released during a violent collision between two circling black holes. These waves are invisible ripples in space.
So how what sets this new merger apart? And why did it give out light? Scientists believe this could be due to a nearby supermassive black hole. Surrounding these monsters is a disc of flowing gas and dust, which may have helped displayed these black holes in action. "At the center of most galaxies lurks a supermassive black hole. It's surrounded by a swarm of stars and dead stars, including black holes. These objects swarm like angry bees around the monstrous queen bee at the centers," says co-author K E Saavik Ford of the City University of New York (CUNY) Graduate Center, the Borough of Manhattan Community College (BMCC), and the American Museum of Natural History (AMNH)."
"This supermassive black hole was burbling along for years before this more abrupt [light] flare," says Matthew Graham, a research professor of astronomy at Caltech and the lead author of the study. "In our study, we conclude that the flare is likely the result of a black hole merger," he adds.
The product of the merger -- a newly formed black hole -- experiences a kick, which pushes it through the gas and dust around the supermassive monster, "It is the reaction of the gas to this speeding bullet that creates a bright flare, visible with telescopes," says co-author Barry McKernan, also of the CUNY Graduate Center, BMCC, and AMNH. These findings need to be confirmed. The researchers say that the light could be from another source. According to Saavik Ford, a co-author based at the City University of New York, the window of doubt was narrow. “We are 99.9% sure,” she says.
To catch light flares, the team scanned the skies using the National Science Foundation's Laser Interferometer Gravitational-wave Observatory, or LIGO, and the European Virgo detector in Italy. They found one such flare and traced it back to the supermassive black hole. It continued to glow for a few days after the merger, slowly fading away with time. They could not study it extensively. In the future, the team hopes to spot more flares as black holes could find themselves in contact with the gas and dust around this supermassive monster again.
"Supermassive black holes like this one have flares all the time. They are not quiet objects, but the timing, size, and location of this flare was spectacular," says co-author Mansi Kasliwal, an assistant professor of astronomy at Caltech. "The reason looking for flares like this is so important is that it helps enormously with astrophysics and cosmology questions. If we can do this again and detect light from the mergers of other black holes, then we can nail down the homes of these black holes and learn more about their origins," she added.
The study is published in the journal Physical Review Letters.