When a star and a supermassive black hole meet, the force of gravity tears the star apart : the matter that composes it is dislocated, then rotates very quickly before being engulfed by the black hole. Exceptionally, it happens that the latter emits jets of matter traveling at a speed close to light.
It is precisely this very rare emission, named this time AT2022cmc, that the teams were able to observe, and which is the subject of a publication on November 30 in the journal Nature.
The last observation of a similar event was in 2012, so the teams were able to take advantage of new methods, including the Zwicky Transient Facility project : a powerful camera, coupled with specific software, allowing scientists to detect an atypical event in real time and sound the alarm.
The rapid coordination between the research teams, each specialized in a type of observation, was then central in the observation of AT2022cmc.
The Noema2 radio telescope contributed to the characterization of the source and, thanks to the X-shooter Very Large Telescope of ESO, it was possible to evaluate the origin of this rare phenomenon : estimated at 8.5 billion light-years from the Earth and in the center of its host galaxy.
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Read also on this subject the news published on the ESO website :
Most distant detection of a black hole swallowing a star
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Once the luminous intensity of this jet of matter is reduced, the galaxy where this event took place can be verified with the Hubble or James Webb space telescopes.
For the moment, scientists do not yet know why some encounters between stars and black holes emit these jets, while others do not. One of the hypotheses put forward is that the black holes associated with these types of events rotate rapidly on themselves. This rotation would then allow to feed jets as luminous as the one produced by AT2022cmc.
Scientists hope that the capabilities of the Vera Rubin Telescope which should be operational in 2024, and for which France is one of the main contributors, will allow to lift the veil on these rare and still mysterious events.