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The record-breaking gamma-ray burst detected in October 2022 has been classified as a once-in-a-millennial event.
It’s called GRB 221009A and its light emission contains up to 18 teraelectronvolts of energy, making it the most powerful gamma-ray burst ever recorded.
We’ve been waiting to know more about this amazing outburst, and now three papers have been submitted to The Astrophysical Journal Letters and posted on the arXiv preprint server.
According to the analysis, this unusual burst of light breaks the rules:
The light curve of its afterglow does not quite match the theoretical descriptions of its behavior, suggesting that GRB 221009A is interesting and unique.
In short, gamma-ray bursts are the most intense in the universe, releasing more energy than the Sun can release in 10 billion years. bursts of electromagnetic radiation caused by catastrophic events, such as the supernova explosions or supernovas that massive stars experience at the end of their lives, or collisions of binary systems involving at least one neutron star.
On October 9, 2022, GRB 221009A was originally thought to be a less intense X-ray from a relatively close source. However, later research revealed that the bright flash came from a much farther distance than originally estimated – 2.4 billion light-years (still making it one of the fastest gamma-ray bursts ever). undetected relatives), suggesting that it is also much stronger than previously believed.
73 days after the initial discovery, astronomers tracked the evolution of the star’s light curve, the shape that the star’s light intensity shows on a graph over time. After 70 days, they could not continue because the afterglow had moved behind the Sun, but it would soon reappear.
In a paper led by Maia Williams of Pennsylvania State University, a team of astronomers found that the X-rays emitted by GRB 221009A shortly after the explosion were an order of magnitude brightest ever detected by the Observatory. Swift astronomy. In a simulation of randomly generated explosions, only one out of 10,000 was as powerful as GRB 221009A.
“We estimate,” they write, “that GRBs as energetic and nearby as GRB 221009A occur at a rate of ≲1 per 1000 yr – making this a truly remarkable opportunity unlikely to be repeated in our lifetime.”
The development of residual magnetism, which does not follow standard theory, is what makes GRB truly special. Normally, gamma-ray bursts are followed by the glow of electrons traveling at close to the speed of light. This phenomenon, known as synchrotron emission, is caused by the shock waves generated during the initial explosion impacting the interstellar medium.
Gamma-ray bursts are thought to consist of energy concentrated in parallel rays that form highly collimated rays. Examining the synchrotron emission could then help astronomers determine the shape of the explosion and its jet rays. According to Williams and his team, the halo indicates that the jet structure of GRB 221009A is more complex than expected or not precisely collimated. According to them, the latter scenario would have a significant impact on the event’s energy budget.
In a separate paper led by Tanmoy Laskar of the University of Utah, a team of astronomers suggests that the particular afterglow may indicate an additional source of synchrotron emission in the gamma-ray burst echo, but the system The results can be more serious. They suggest that there may be a fundamental flaw in the theory of synchrotron residual magnetism.
And a third study, led by astronomer Manisha Shrestha of the University of Arizona, concluded that the halo lacks some of the characteristics one would expect from a supernova explosion. This could mean that much of GRB 221009A’s energy budget was spent on the jets, leaving little evidence that an exploding star was responsible.
This month, the halo will reappear from behind the Sun and will still be clearly visible to our multi-wavelength telescopes. No matter what happens to this particular outburst, astronomers will work hard to determine the cause.
All research papers have been submitted to The Astrophysical Journal Letters and are accessible on the arXiv preprint server. They are available here, here and here.
