The unusual jet structure reveals unique features of the relatively nearby gamma-ray burst that can be studied in better detail than the gamma-wave bursts discovered so far
When astronomers discovered the gamma-ray burst called GRB 221009A on October 9, 2022, they called it "the brightest of all time." Now, months after the initial burst, scientists studying GRB 221009A describe an unusual structure of the jet of material ejected during the burst that may explain the extreme nature of GRB 221009A and why we continued to see its secondary flash so long after the event.
Gamma bursts are the most violent and energetic explosions in the universe, they release in a few seconds the same amount of energy that the sun produces during its entire life. According to the scientists, GRB 221009A is the result of the collapse of a massive star into a black hole.
After examining data at different wavelengths from October's gamma-ray burst, the research team found that GRB 221009A's jet has a narrow core and broad swept wings. This is different from the types of jets seen in gamma-ray bursts that create other cataclysmic events and may explain why scientists continued to see the multi-wavelength flash of GRB 221009A months after the explosion.
"GRB 221009A greatly advances our understanding of gamma-ray bursts, showing that the most extreme bursts do not obey the standard physics assumed for G-type gamma-ray bursts," says Brendan O'Connor, lead author of the study. O'Connor led the study that used the Gemini South telescope in Chile to observe the event last October. "GRB 221009A may be the Rosetta Stone of long gamma-ray bursts, forcing us to re-examine our standard theories of how the relativistic jets in collapsing massive stars form."
The findings will lead to more studies on gamma-ray bursts and encourage scientists to develop simulations of the jet structures of gamma-ray bursts.
"For a long time we thought the jets were shaped like ice cream cones," says Alexander van der Hoost, associate professor of physics at George Washington University and co-author of the study. "Some of the gamma-ray bursts in recent years, and especially this study, show that we need more complex models and detailed computer simulations of the jets of gamma-ray bursts."
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