Scientists discovered a gamma-ray burst that happens once every 10,000 years and was 70 times brighter than any previously observed.
Gamma-ray bursts (GRB) are the most intense type of explosion known to science.
The GRB 221009A was discovered when X-rays were detected by NASA‘s Neil Gehrels Swift Observatory on October 9, 2022. While the source looked to be in the Milky Way galaxy, close to the galactic centre, evidence from Swift and NASA’s Fermi Gamma-Ray Space Telescope quickly revealed it was considerably further out.
The explosion was subsequently traced back to a far more distant galaxy that happened to be behind our own, according to observations from the European Southern Observatory’s Very Large Telescope. AGRB 221009A generated such a strong pulse of light that it rushed over the solar system that scientists promptly called it the BOAT — the brightest of all time.
“GRB 221009A was likely the brightest burst at X-ray and gamma-ray energies to occur since human civilization began,” said Eric Burns, an assistant professor of physics and astronomy at Louisiana State University in Baton Rouge.
After analysing 7,000 GRBs, most of which were observed by NASA’s Fermi Telescope and the Russian Konus sensor on NASA’s Wind satellite, he determined that such a bright event may occur only once per 10,000 years.
Additional calculations reveal that GRB 221009A lasted only a few seconds and deposited around a gigatonne of energy into Earth’s upper atmosphere. It is the energy output of a terrestrial power plant.
“So many gamma rays and X-rays were emitted that it excited the ionosphere of the Earth,” said Erik Kuulkers, ESA Project Scientist for Integral, one of the spacecraft that detected the GRB.
A number of other ESA spacecraft, XMM-Newton, Solar Orbiter, BepiColombo, Gaia, and SOHO, also detected the GRB or its effects on our galaxy. The event was so bright that even today the residual radiation, known as the afterglow, is still visible and will remain so for a long time yet, space scientists said.
“We will see the afterglow of this event for years to come,” said Volodymyr Savchenko, University of Geneva, Switzerland, who is currently analysing the data from ESA’s INTEGRAL observatory.
The burst was so intense that it effectively blinded most gamma-ray equipment in space, preventing them from recording the true intensity of the emission.
The Fermi data allowed American scientists to reassemble this knowledge. They then matched their findings to those of the Russian team working on Konus data and Chinese researchers analysing observations from their SATech-01 satellite’s GECAM-C detector and equipment on their Insight-HXMT observatory.
Scientists gathered massive amounts of data from disparate devices to figure out how the original explosion occurred and how the radiation interacted with other stuff on its voyage across space.
They presented their findings at the 20th Conference of the High Energy Astrophysics Division of the American Astronomical Society (AAS) in Hawaii, US, in a focus issue of The Astrophysical Journal Letters.