Last year, the European Southern Observatory’s Very Large Telescope (ESO’s VLT) went on alert after the survey telescope detected an unusual visible light source. The VLT, along with other telescopes, quickly moved to the source: a supermassive black hole in a distant galaxy that swallowed a star and ejected the debris with a jet. The VLT determined that this was the most distant example of such an event ever observed. As the jet is almost pointed at us, it’s also the first time it’s been detected in visible light, providing a new way to detect these extreme phenomena.

Stars orbiting very close to a black hole are shattered by the black hole’s incredible tidal forces in what’s known as a tidal disruption event (TDE). About 1% of these cause jets of plasma and radiation from the poles of a rotating black hole. John Wheeler, pioneer of black hole research in 1971^[1] He presented his concept of jet TDEs as “a tube of toothpaste compressed tightly in the middle” causing the system to “remove material from both ends”.

This artist’s impression shows what it might look like when a star gets too close to a black hole, the star being compressed by the black hole’s intense gravity. Some of the star’s material is pulled in and rotates around the black hole, forming the disk seen in this image. In rare cases like this, matter and radiation emanate from the poles of a black hole. In the case of the AT2022cmc event, evidence of jets was detected by various telescopes, including the VLT, which determined it to be the most distant example of such an event. Image source: ESO/M.Kornmesser

“We’ve only seen a few of these jet TDEs, and they remain very exotic and poorly understood phenomena,” says Niall Tanvir, from the University of Leicester in the UK, who made observations to determine the object’s distance from the VLT. So astronomers are constantly looking for these extreme phenomena to understand how jets actually form and why such a small fraction of the TDE creates them.

As part of this search, many telescopes, including the Zwicky Transient Facility (ZTF) in the US, repeatedly scan the sky for signs of short-lived, often extreme events, which can then be studied in more detail with telescopes like ESO’s VLT. . . “We have developed an open source data pipeline to store and extract key information from the ZTF research and alert us to unusual events in real time,” explains astronomer Igor Andreoni of the University of Maryland in Chile, USA. . Published today in Nature with Michael Coughlin of the University of Minnesota.

This animation is an artist’s impression of a star collapsing into a black hole at the center of a distant galaxy, creating jets of matter and radiation. Dubbed AT2022cmc, as the jets point almost at us, the event was detected from Earth for the first time with an optical telescope. Image source: ESO/M.Kornmesser

Last February, ZTF discovered a new visible light source. Dubbed AT2022cmc, the event was similar to a gamma-ray burst, the most powerful light source in the universe. The prospect of witnessing this rare phenomenon has prompted astronomers to launch several telescopes around the world to observe the mysterious source in more detail. This included ESO’s VLT, which was rapidly observing this new event with the X-shooter instrument. The VLT data placed the source at an unprecedented distance for these events: The light produced by the AT2022cmc began its journey when the universe was about a third of its current age.

Lights ranging from high-energy gamma rays to radio waves have been collected by 21 telescopes around the world. The team compared this data to a variety of known events, from stellar collapses to kilobytes. But the only scenario that fit the data was a rare reactive TDE directed at us. Giorgos Leludas, an astronomer at DTU Space in Denmark and one of the study’s co-authors, said: “As the relativistic jet is pointed at us, it makes the event much brighter and visible over a wider range than it would normally be visible. electromagnetic spectrum”.

VLT distance measurements showed the AT2022cmc to be the furthest TDE ever detected, but that’s not the only record-breaking aspect of this object. “Until now, few known jet TDEs were initially detected with high-energy gamma-ray and X-ray telescopes, but this was the first discovery in an optical study,” says Daniel Perley, an astronomer at Liverpool John Moores University. in the UK and co-author of the study. This demonstrates a new way of detecting the TDE jet, allowing further study of these rare events and exploration of the extreme environments around black holes.