Mysterious flare from space was caused by a star “eaten” by a black hole

An international team of researchers solved the mystery of a mysterious flare up recorded in early 2022. Its source turned out to be a star torn apart and eaten by a supermassive black hole.

Mysterious explosion from the past

In February 2022, the ZTF telescope registered the appearance of a new visible light source in the sky. It received the designation AT2022cmc. The flare resembled a gamma-ray burst — the brightest electromagnetic event in the Universe. The prospect of studying such a rare phenomenon led to the fact that astronomers aimed at AT2022cmc several telescopes around the globe at once. Among them was the ESO’s Very Large Telescope (VLT). According to its data, the source was located at an unprecedented distance for such events: the light emitted during the AT2022cmc flare began its journey when the age of the Universe was about a third of the current one.

ESO’s Very Large Telescope (VLT). Source: ESO/M. Claro

In total, twenty-one telescopes participated in the observations of AT2022cmc. Astronomers have collected a huge amount of diverse information ranging from high-energy gamma rays to radio waves. Then the researchers compared it with the data collected during the study of various types of known astronomical phenomena from collapsing stars to kilonovae. But the only scenario that corresponded to the observations obtained was a rare phenomenon: the tidal destruction of a star with a jet aimed directly at us. 

Tidal destruction of a star

Tidal disruption events occur when a star passes at a very short distance from a supermassive black hole. Its powerful tidal forces literally tear the star apart. In about 1% of cases, such an event is accompanied by the expiration of jets – jets of plasma and radiation from the circumpolar regions of a rotating black hole. In 1971, astrophysicist John Wheeler figuratively compared this to “a tube of toothpaste tightly squeezed in the middle,” which is why jets of matter fly out of the system from both ends”.

Absorption of the remains of a star by a black hole in the artist’s image. Source: ESO/M.Kornmesser

According to the researchers, so far they have observed only a handful of tidal disruption events with jets, because of which their mechanism is rather poorly explained. Therefore, astronomers are constantly searching for such phenomena to understand how jets are formed and why it happens so rarely.

In the case of the AT2022cmc, the scientists were very lucky. The jet was aimed directly at the Earth. Therefore, despite the record distance, the event looked much brighter than usual, and it could be observed in a wider range of the electromagnetic spectrum, including visible light. This made it possible to collect unique data that will help shed light on the nature of such events in the future.

According to

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