(Nanowerk News) International astronomers, including some Aussies, have been able to piece together data showing that a supermassive black hole has been snacking on a nearby star. These star chomping events are known as tidal disruption events (TDE), and the researchers say they have been able to detect the bursts of energy from the star as it is torn apart. TDEs are fairly rare to witness, as black holes tend to not even let light out when gobbling up nearby matter. They say this TDE happened in a galaxy 12.4 billion light years away, and was only visible here on Earth due to its exceptional bright bursts.
This extraordinarily bright cosmic explosion was caught by the Zwicky Transient Facility on 11 February 2022. Follow-up observations by several dozen space and ground telescopes gave one the most comprehensive view of the birth of a relativistic jet from a black hole.
Swinburne Professor Jeff Cooke, who is also a Chief Investigator for the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), was a key member of the research team.
“Stars that are literally torn apart by the gravitational tidal forces of black holes help us better understand what exists in the Universe,” says Professor Cooke.
“These observations help us explore extreme physics and energies that cannot be created on Earth.”
Supermassive, super rare and super far away
When a star gets too close to a supermassive black hole, the star is violently ripped apart by tidal forces, with pieces drawn into orbit around the black hole and eventually completely consumed by it.
In extremely rare instances – only about one per cent of the time – these so-called tidal disruption events (TDEs) also launch luminous jets of material moving almost at the speed of light.
The co-lead authors of the work, Dr Igor Andreoni from the University of Maryland and Assistant Professor Michael Coughlin from the University of Minnesota, along with an international team, observed one of the brightest ever TDEs. They measured it to be more than 8.5 billion light years away, or more than halfway across the observable Universe.
The event, officially named “AT2022cmc”, is believed to be at the centre of a galaxy that is not yet visible because the intense light from the flash still outshines it. Future space observations may unveil the galaxy when AT2022cmc eventually fades away.
It is still a mystery why some TDEs launch jets while others do not appear to. From their observations, the researchers concluded that the black holes associated with AT2022cmc and other similarly jetted TDEs are likely spinning rapidly.
This suggests that a rapid black hole spin may be one necessary ingredient for jet launching—an idea that brings researchers closer to understanding these mysterious objects at the outer reaches of the universe.
Working together on new discoveries
More than 20 telescopes operating at all wavelengths were a part of this research.
These include the Zwicky Transient Facility in California that made the initial discovery, X-ray telescopes in space and on the International Space Station, radio/mm telescopes in Australia, the US, India and the French Alps, and optical/infrared telescopes in Chile, the Canary Islands and the US, including the W. M. Keck Observatory in Hawaii.
Swinburne postdoctoral researcher Jielai Zhang, a co-author on the research, says that international collaboration was essential to this discovery.
“Although the night sky may appear tranquil, telescopes reveal that the Universe is full of mysterious, explosive and fleeting events waiting to be discovered. Through OzGrav and Swinburne international research collaborations, we are proud to be making meaningful discoveries such as this one,” she said.
