Black holes aren’t exactly polite eaters.
For the first time, scientists observed a black hole both devouring a star and ripping a plasma ‘burp’ as it consumed its meal — an incredibly rare find. Scientists have previously seen a black hole consume a star, and they’ve also seen black holes spew superheated matter, but this is the first time they’ve seen both events occur so closely together. Viewing this particular disappearing act at the center of a nearby galaxy has shed light on a previously theoretical phenomenon and brought researchers closer to understanding the physics of black holes.
A Historic First
Ever since researchers at Ohio State University noticed a star roughly the size of the sun being pulled into a black hole in December 2014, a team of scientists led by Johns Hopkins University professor Sjoert van Velzen fixed its eyes on the hungry black hole, located roughly 300 million light years from Earth. Over the course of several months, van Velzen’s team watched the black hole siphon material from the doomed star until it was entirely devoured. Using a combination of X-ray, radio and optical signals, the team tracked the star’s demise across multiple wavelengths, which allowed them to piece together a more complete picture of what happens when a black hole snacks on a star.
Jets of X-ray and gamma ray radiation emanating from black holes have been documented before, but never as a direct result of a star being consumed. Black holes periodically emit particles from accretion disks, or rings of particles caught in their gravitational pull. It had been hypothesized that a similar emission would occur if a large body, such as a star, were dragged into a black hole. Scientists, however, had never been able to observe such an event. So, when researchers noticed an abrupt spike in activity around the black hole back in 2014, they knew they were about to watch something special. The size and intensity of the flare ruled out the possibility that it was caused by the black hole’s accretion disk, leaving few other possibilities.
“Previous efforts to find evidence for these jets, including my own, were late to the game,” van Velzen said in a news release.
Because they caught the black hole in the act this time, researchers were able to confirm the theory that black holes emit flares of radiation in the process of consuming large quantities of matter. While this phenomenon is still largely a mystery, it is thought that the jets are caused by magnetic fields interacting with the particles swirling around a black hole. The team published their findings last week in the journal Science.
“The destruction of a star by a black hole is beautifully complicated, and far from understood,” van Velzen said. “From our observations, we learn the streams of stellar debris can organize and make a jet rather quickly, which is valuable input for constructing a complete theory of these events.”