Brightest-ever space explosion might owe its strength to unique jet structure, finds study

Scientists unravel the mystery behind the brightest known explosion since the Big Bang - GRB 221009A.

Astronomers surmise that the powerful blast of radiation came from the birth of a black hole. (Image credit: NASA)

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An exceptionally bright and long-lasting pulse of radiation from a space explosion swept over the planet on October 9, 2022. It was a gamma-ray burst (GRB). They are the most powerful types of explosions in the universe. The one that happened on that day, GRB 221009A, was the brightest of its kind. This means that it is the most powerful explosion we know since the big bang.

Now, scientists may finally know what caused the GRB to be so bright, according to a research article published in the journal Science Advances on Wednesday.

Being the most violent and cataclysmic explosions in the universe, GRBs are known to release the same amount of energy in a few seconds as our Sun will produce during its entire lifetime. Scientists believe that GRB 221009A, also known as BOAT, or brightest of all time, was caused by a massive star collapsing into a black hole. It was so powerful that it effectively blinded many gamma-ray instruments in space, meaning that they could not measure its actual intensity.

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This illustration depicts how such gamma-ray bursts are typically formed. (Credit: NASA’s Goddard Space Flight Center)

But the authors of the new article went through a hoard of multi-wavelength data from the gamma-ray burst and found that its ‘jet’ seemed to have a narrow core with wide sloping wings. This made it different from other types of jets seen in GRBs which were produced by other violent cosmic events. This may also explain why scientists were able to see its multi-wavelength glow for months after the explosion.

“GRB 221009A represents a massive step forward in our understanding of gamma-ray bursts, and demonstrates that the most extreme explosions do not obey the standard physics assumed for garden variety gamma-ray bursts,” explained Brendan O’Connor, lead author of the article, in a press statement. O’Connor is a graduate student at George Washington University.

According to Hendrik Van Eerten, co-author of the article, the study shows that the GRB has a unique structure that includes a narrow jet embedded within a wider gas outflow. Van Eerten is a professor at the Department of Physics at the University of Bath in the UK.

For a long time, scientists have thought about these jets as being shaped like ice cream cones, according to Alexander van der Horst, study co-author and a professor of physics at George Washington University. But recent studies into GRBs, and in particular, the study on BOAT, tells astronomers that there needs to be more complex models and detailed simulations of the jets of these humongous explosions.