According to a new study, not all light streaming from the surrounding disk of a black hole easily escapes. A black hole bends light back on itself.
A lot of you have probably heard about the famous saying that nothing can escape a black hole. Not even light. Well, that’s not completely true.
In the vicinity of a black hole, light can not escape. But a bit farther out, in disks of material that swirl around some black holes, light can escape. And that’s why some black holes sparkle in X-rays.
Scientists have previously theorized that some of the light that escapes around massive black holes nearly doesn’t make it, and now they’ve finally seen it happen.
According to a new study accepted for publication in The Astrophysical Journal, not all light streaming from the surrounding disk of a black hole easily escapes. Some light surrenders to the strong gravitational pull of the black hole, turns right back, and then ultimately bounces off the disk and escapes.
“We observed light coming from very close to the black hole that is trying to escape, but instead is pulled right back by the black hole like a boomerang,” Riley Connors, lead author of the new research and a physicist at Caltech, said in a statement. “This is something that was predicted in the 1970s, but hadn’t been shown until now.”
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Scientists who conducted the study were analyzing old observations of a black hole feeding on a sunlike star. As the black hole “feeds” off this star, it pulls material onto the accretion disk around it.
Scientists were looking closely at the X-ray light coming from the disk that was spiraling toward the black hole and that’s when they found imprints indicating that light failed to escape the disk and got pulled back toward the black hole before being reflected out into space.
“The disk is essentially illuminating itself,” Javier Garcia, a physicist at Caltech and co-author of the new research, said in the same statement. “Theorists had predicted what fraction of the light would bend back on the disk, and now, for the first time, we have confirmed those predictions.”
The team relied on observations assembled by NASA’s Rossi X-ray Timing Explorer, which watched black holes and neutron stars. The spacecraft launched in 1995 and took its last information in 2012.
The scientists say that the new results offer another indirect confirmation of Albert Einstein’s general theory of relativity, and also will help in future measurements of the spin rates of black holes, something that is still poorly understood.
The researchers are also trying to figure out how fast black holes spin.
“Since black holes can potentially spin very fast, they not only bend the light but twist it,” says Connors. “These recent observations are another piece in the puzzle of trying to figure out how fast black holes spin.”