| 6 December 2023, Wednesday |

Astronomers capture first direct evidence of black hole spinning

In a groundbreaking development, astronomers have made a historic discovery by providing the first direct evidence confirming the rotation or spinning of a black hole.
The observations gave astronomers new insights regarding enigmatic celestial objects, as the scientists focused on the supermassive black hole which is present at the centre of the neighbouring Messier 87 (M87) galaxy. The Event Horizon Telescope had imaged the shadow of Messier 87 (M87) galaxy.

Just like other supermassive black holes, M87 also features powerful jets which were launched from the poles almost at the speed of light into intergalactic space.

Till now, scientists have believed that cosmic jets are powered by the spinning of a black hole, however, until now they did not have any direct evidence.
Speaking to The Guardian, co-author of the study and the national astronomical observatory of Japan’s Dr. Kazuhiro Hada said, “After the success of black hole imaging in this galaxy with the Event Horizon Telescope, whether this black hole is spinning or not has been a central concern among scientists. Now anticipation has turned into certainty. This monster black hole is indeed spinning.”

Lead author of the Shanghai Astronomical Observatory Dr Ru-Sen Lu said that the scientific community are aware of jets getting ejected from the region surrounding black holes.

“But we still do not fully understand how this happens,” said Lu, adding that they need to observe the jet’s origin as close as possible to the black hole.

M87, which is located 55 million light years from the Earth, has a black hole which is 6.5 billion times larger than the Sun. As per the scientists, an accretion disk of gas as well as dust swirling on the precipice of the cosmic sinkhole appears beyond the black hole.
According to them, some of these particles fall into the black hole and disappear forever. However, a small fraction gets ejected out from the poles of the black hole at a speed which is more than 99.99 per cent of the speed of light.

As per the study, the scientists observed a recurring 11-year cycle in the jet, which was found to precess near a central point at the black hole’s edge. This observation showed a misalignment between the spin axis of the black hole and the accretion disk, because of which the jet moved like a spinning top.
“Detecting this precession provides unequivocal evidence that the supermassive black hole in M87 is indeed spinning, thus enhancing our understanding of the nature of supermassive black holes,” said the authors.

Speaking to The Guardian, an astrophysicist at UCL Dr Ziri Younsi said, “That’s exciting because it’s telling us that it can only precess if the black hole has non-zero spin. It’s an indirect but extremely strong confirmation of spin.”



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