Einstein right, again: Researchers see light 'echo' around black hole

For the first time ever, scientists have seen the light from behind a black hole.

Black holes are regions in space-time where gravity’s pull is so powerful that not even light can escape its grasp. However, while light cannot escape a black hole, its extreme gravity warps space around it, which allows light to “echo,” bending around the back of the object. Thanks to this strange phenomenon, astronomers have, for the first time, observed the light from behind a black hole.

In a new study, researchers, led by Dan Wilkins, an astrophysicist at Stanford University in California, used the European Space Agency’s XMM-Newton and NASA’s NuSTAR space telescopes to observe the light from behind a black hole that’s 10 million times more massive than our sun and lies 800 million light-years away in the spiral galaxy I Zwicky 1, according to a statement from ESA.

An infographic depicting the light from behind a black hole. (ESA)
An infographic depicting the light from behind a black hole. (ESA)

The light "echo" was first predicted by Albert Einstein in his general theory of relativity, published in 1916.

This study began with the researchers’ desire to expand our understanding of black hole coronas, which are the source of the X-ray light that often radiates from the vicinity of these objects. . Bright flares of X-ray light are emitted by gas that falls into black holes from their accretion disks, the disks of dust and gas that surround and “feed” these objects.

The team spotted an X-ray flare in I Zwicky 1 that was so bright that some of the light reflected on the gas falling back into the black hole. When that reflected light was bent around the back of the black hole by the object’s extreme gravity, the team was able to spot it using the ESA and NASA space telescopes.

The team didn’t just observe this light, which is the first time it has been directly observed like this; they also took note of how the X-ray light changed color as it bent and moved around the back of the black hole. By observing the light’s journey around the back of the black hole, the researchers hope to understand more about what really goes on that close to these gravitational vortexes.

Following this groundbreaking study, the team aims to create a 3D map of the black hole’s surroundings, according to the statement. They also hope to better understand black hole coronas and explore how the corona of a black hole is capable of producing these bright X-ray flares.

This work was described in a study published Wednesday in the journal Nature.