Artist's visualization of GRB 221009A
The brightest burst of gamma rays ever recorded was caused by the collapse and explosion of a massive star—a supernova.
That’s according to a paper published last week in Nature Astronomy that used data from NASA’s James Webb Space Telescope.
Traveling from 2.4 billion light-years away, GRB 221009A—nicknamed the “BOAT,” the brightest of all time— reached the solar system on Sunday, Oct. 9, 2022.
Brightest Of All Time
Although it lasted only 10 hours, GRB 221009A was 70 times brighter than any yet seen and said to be a once-in-10,000-years event. It was so bright that it saturated most of the world’s gamma-ray detectors.
The most potent class of explosions in the universe—a gamma-ray burst—are jets of particles accelerated into space at near-light speed. They’re thought to originate in supernovas, but none were seen in the immediate aftermath of the explosion’s detection in the direction the GRB came from—the constellation Sagitta.
Thanks to a fast reaction by observers and staff, near-simultaneous observations were made of ... [+]
Search For Gold
While one mystery was solved, another deepened. While scientists are now sure that a supernova caused GRB 221009A, no traces of gold and platinum were found. Heavy elements such as these (elements heavier than iron) were thought to originate in supernovas, but now scientists are not so sure.
“When we confirmed that the GRB was generated by the collapse of a massive star, that allowed us to test a hypothesis for how some of the heaviest elements in the universe are formed,” said Peter Blanchard, a postdoctoral fellow at Northwestern University, Evanston, Illinois, who led the study. “We did not see signatures of these heavy elements, suggesting that highly energetic GRBs like the BOAT do not produce these elements. It suggests that supernovas are not the primary source of heavy elements in the universe.
The small constellation of Sagitta the Arrow framed with a field of view similar to binoculars, and ... [+]
Supernova Signature
JWST was used about six months after the GRB was detected. “The GRB was so bright that it obscured any potential supernova signature in the first weeks and months after the burst,” said Blanchard. “At these times, the so-called afterglow of the GRB was like the headlights of a car coming straight at you, preventing you from seeing the car itself.”
Scientists had to wait for it to fade significantly to give them a chance of seeing the supernova. However, while the supernova’s tell-tale elements, including calcium and oxygen, were detected, the supernova itself wasn’t bright. “You might expect that the same collapsing star producing a very energetic and bright GRB would also produce a very energetic and bright supernova,” said Blanchard. “But it turns out that’s not the case. We have this extremely luminous GRB, but a normal supernova.”
The event produced some of the highest-energy photons ever recorded by satellites designed to detect gamma rays. “We are fortunate to live in a time when we have the technology to detect these bursts happening across the universe,” said Blanchard.
Wishing you clear skies and wide eyes.
