An astrophysicist from Stanford University made the first direct observation of light from behind a black hole, a press statement reveals. In doing so, they confirmed a prediction made in Einstein's theory of general relativity.
The observation is unusual due to the fact that black holes are known for sucking in all surrounding matter and light, meaning we should not be able to see light from behind one of the massive celestial objects.
The dark side of the black hole
While analyzing X-rays emitted by a supermassive black hole 800 million light-years from Earth, Stanford University astrophysicist Dan Wilkins noticed a series of bright flares of X-rays, which were unusual but not unprecedented. Following that observation, however, he saw more flashes of X-rays in a different "color" — these smaller flashes were consistent with theories regarding X-rays reflected from behind a black hole, a scenario that had only been theorized and had never been observed before.
The theories state that smaller flashes, occurring shortly after larger ones are the same X-ray flares as the larger flashes, just reflected from the far side of the black hole. "Any light that goes into that black hole doesn’t come out, so we shouldn’t be able to see anything that's behind the black hole," said Wilkins. "The reason we can see that is because that black hole is warping space, bending light and twisting magnetic fields around itself," he continued. The impressive discovery, outlined in a paper in Nature, was made during an investigation into the black hole corona, a swirling ring of high-energy particles that surrounds the celestial object's central event horizon.
Shedding light on the warped space surrounding black holes
There is much we don't fully understand about black holes. Over the years, this has led to many theories and predictions that are continuously tested with the latest observatory technologies. Last year, for example, astronomers at MIT observed the corona of a black hole mysteriously disappear and then reappear — it may or may not have been caused by a star caught in the black hole's gravitational pull.
Wilkins and his team made their observations and analysis using data from the European Space Agency's (ESA's) XMM-Newton and NASA's NuSTAR space telescopes. The black hole they observed is at the center of a spiral galaxy called I Zwicky 1.
In the future, observatories such as the ESA's X-ray observatory, Athena (Advanced Telescope for High-ENergy Astrophysics) will help the astronomical community to continue to gain a better understanding of the coronas of black holes as well as the role black holes have played in the evolution of the universe. The much-delayed James Webb Telescope, which should finally launch later this year, will also aid in increasing our understanding of the earliest black holes. All of this could help us to better understand our own place in the cosmos. According to Wilkins, "the picture we are starting to get from the data at the moment is going to become much clearer with these new observatories."