An explosion in space believed to be caused by a massive star collapsing on itself to form a black hole may have been the brightest blast ever seen. Astronomers say the event was the most intense since the beginning of human civilisation.
The explosion happened two billion light years from Earth and blinded space instruments. It produced a pulse of radiation that swept through the solar system in October last year.
Scientists said this type of event is a gamma-ray burst (GRB), and have named it GRB 221009A. An analysis of 7,000 GRBs suggests that GRB 221009A is 70 times brighter than any yet seen and an event like this occurs once every 10,000 years.
Dr Dan Perley, of the Astrophysics Research Institute at Liverpool John Moores University – who followed the event with the University’s Liverpool Telescope on the Spanish island of La Palma, said: “There is nothing in human experience that comes anywhere remotely close to such an outpouring of energy. Nothing.”
Though they last only seconds, GRBs produce as much energy as the Sun will emit during its entire lifetime. Dr Perley said: “The star would have been many times more massive than the Sun, probably 20 times as massive or more.”
It is thought that GRB 221009A was so bright because it was much closer to Earth compared to other known GRBs and the beam of electromagnetic radiation happened to be pointing in the direction of the planet. Andrew Levan, a professor of astrophysics at Radboud University in Nijmegen, Netherlands, said: “We cannot say conclusively that there is a supernova, which is surprising given the burst’s brightness.
“If it’s there, it’s very faint. We plan to keep looking, but it’s possible the entire star collapsed straight into the black hole instead of exploding.”
GRBs are usually followed by a shockwave that emits lower energy radiation, known as an afterglow, that gradually fades over time.
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Dr Gavin Lamb, a Royal Society Dorothy Hodgkin Research Fellow at Liverpool John Moores University - who was part of an international team that used Nasa’s James Webb Space Telescope to observe the GRB 221009A afterglow - said the observations provide “a unique insight into the mechanisms responsible for these transient flashes of light”.
He said: “There is a lot more data yet to sift through and we will be looking for clues to explain the relationship between GRBs and supernovae from massive stars, and the dynamics within the afterglow. We still don’t fully understand many aspects of such high-energy jets.”
The findings are reported in two separate papers in the Astrophysical Journal and Astrophysical Journal Letters.
