Astronomers are fascinated by the brightest flash ever seen
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Washington (AFP) – Astronomers have observed the brightest flash of light from an event that occurred 2.4 billion light-years from Earth and likely resulted from the formation of a black hole.
The gamma-ray burst — the most intense form of electromagnetic radiation — was first detected by orbiting telescopes on Oct. 9, and its afterglow is still visible to scientists around the world.
Astrophysicist Brendan O’Connor told AFP that gamma-ray bursts that last hundreds of seconds, like the one that occurred on Sunday, are thought to be the death of stars more than 30 times the size of our Sun.
The star explodes in a supernova, collapses into a black hole, then material forms in a disk around the black hole, falls in and out in a jet of energy that travels at 99.99 percent the speed of light.
The flash released photons carrying a record 18 teraelectronvolts — that’s 12 zeros behind the 18 — and it affected long-wave radio communications in Earth’s ionosphere.
“It’s really breaking records, the amount of photons and the energy of photons that are reaching us,” said O’Connor, who used the infrared instrument on the Gemini South Telescope in Chile to make the new observations early Friday.
“Something this bright, this close, is truly a once-in-a-century event,” he added.
“Typical gamma-ray bursts release the same amount of energy as our Sun produces in a few seconds over its entire lifetime — and this event is the brightest gamma-ray burst ever.”
The gamma-ray burst, known as GRB 221009A, was spotted early Sunday morning by telescopes including NASA’s Fermi Gamma-ray Space Telescope, the Neil Gehrels Swift Observatory, and the Wind spacecraft.
1.9 billion year old movie
It originated in the direction of the Sagitta star and traveled approximately 1.9 billion years to reach Earth — less than the current distance from its starting point, because the universe is expanding.
Observing the event now is like watching a 1.9 billion-year-old recording of those events unfold before us, giving astronomers a rare opportunity to glean new insights into things like black hole formation.
“That’s what makes this kind of science so addictive — you get this adrenaline rush when these things happen,” said O’Connor, who is affiliated with the University of Maryland and George Washington University.
He added that although the initial burst might have been visible to lucky amateur astronomers, it had passed out of their field of view.
In the coming weeks, he and others will continue to look for signatures of supernovae at optical and infrared wavelengths, to ensure that their guesses about the source of the flash are correct and that the phenomenon is consistent with known physics.
Unfortunately, although the initial burst may have been visible to amateur astronomers, it has since faded.
Supernova explosions are responsible for creating heavy elements – such as gold, platinum, uranium – and astronomers are expected to be looking for their signatures as well.
Astrophysicists have written in the past that the sheer power of gamma-ray bursts could cause extinction-level events here on Earth.
But O’Connor points out that because jets of energy are so tightly focused and unlikely to originate in our galaxy, this scenario is not something we should worry too much about.
© 2022 AFP
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