Jul 29, 2021 19:00:00

Light from 'beyond a black hole' is observed for the first time

A black hole is a celestial body that swallows even light due to strong gravity, so naturally you should not be able to observe behind the black hole. However, contrary to this intuition, a paper was published on July 28, 2021 that 'rays emitted from the other side of the black hole' were observed. According to the treatise, this phenomenon was predicted by Einstein but never confirmed before.

Light bending and X-ray echoes from behind a supermassive black hole | Nature

https://www.nature.com/articles/s41586-021-03667-0

First detection of light from behind a black hole | Stanford News
https://news.stanford.edu/2021/07/28/first-detection-light-behind-black-hole/

X-rays can echo and bend around the back of supermassive black holes | New Scientist
https://www.newscientist.com/article/2285207-x-rays-can-echo-and-bend-around-the-back-of-supermassive-black-holes/

This time, the 'rays from behind the black hole' were captured by a research team of Stanford University astrophysicist Dan Wilkins and others. Wilkins and colleagues initially observed a galaxy black hole called 'I Zwicky 1' 800 million light-years away from Earth to investigate the phenomenon of 'corona ' found in some black holes.

Wilkins said of the black hole corona, 'The prevailing theory is that when gas is sucked into a black hole, it is generated by an ultra-high temperature of several million degrees Celsius. At such a high temperature, electrons are emitted. It pops out of the atom and creates a plasma and a magnetic field. When this magnetic field approaches a black hole and heats something around it, it emits X-rays. '

When the research team was observing X-rays emitted from a black hole corona, it was recorded that powerful X-ray bursts repeatedly occurred about 60 million kilometers from

the horizon of the black hole event. .. Then, as a result of analyzing two X-ray bursts by the research team, it was found that the second X-ray burst was observed with a weakened first X-ray burst delayed. From this, Wilkins and colleagues concluded that 'the second X-ray burst is a reflection of the first X-ray burst from behind a black hole.'

The following is an illustration of the phenomenon observed this time. Hot gas forms an accretion disk around the black hole.

Then, an X-ray flare is emitted from the corona formed at a height of 60 million km from the black hole.

The X-rays are reflected on the front side of the disk, but ...

What is reflected on the other side of the disk is also observed as a 'reverberation' distorted by the gravity of the black hole. If you click this link , you can see a series of illustrations in GIF animation.

Looking at the flow of X-rays generated from the corona from the side, it looks like this.

Wilkins commented on this phenomenon: 'The light that enters the black hole does not come out, so if you think about it normally, you should not be able to see what is behind the black hole. It was observed because, just as a black hole distorts space and twists light, it also distorts the magnetic field around it. '

Co-authors of the paper, Luke Blossom and Roger Blandford, said, '50 years ago, astronomers who had speculated on how a magnetic field near a black hole behaves would observe it directly. You wouldn't have expected that the day would come when Einstein's general theory of relativity could actually be confirmed due to the development of such technology. '

The research team plans to continue researching black holes through the European Space Agency's X-ray observation project ' Athena (Advanced Telescope for High-ENergy Astrophysics) ' to deepen their understanding of the birth and formation of galaxies. ..