(ORDO NEWS) — The record-breaking gamma-ray burst, discovered in October 2022, is now described as a once-in-a-thousand-year event.
It is called GRB 221009A and has a power of up to 18 teraelectronvolts. the energy contained in its light emission is considered the most powerful gamma-ray burst in the entire history of observations.
We’ve been waiting to learn more about this incredible explosion, and now the analyzes have begun to come in as preprints. arXiv server, with three papers submitted to The Astrophysical Journal Letters .
According to analyses, this exceptional burst of light breaks the rules: its afterglow light curve does not adhere to well-defined theoretical descriptions of how it should happen, suggesting that there is something interesting and unique about GRB 221009A.
Recall that gamma-ray bursts are the most powerful explosions in the universe, erupting with fire. and the fury is so powerful that they release more energy than the Sun in 10 billion years.
Bursts of electromagnetic radiation are caused by catastrophic events: supernova or hypernova explosions that occur near massive stars at the end of their lives, or collisions of binary systems involving at least one neutron star.
The burst GRB 221009A was first detected. October 9, 2022 and was initially thought to be a less powerful burst of X-rays from a relatively nearby source.
However, subsequent observation showed that the flash of light came much further than originally thought – 2.4 billion light-years (which still makes it one of the closest gamma-ray bursts ever detected), which means that she was much more powerful. than expected at first.
For 73 days after the initial discovery, astronomers watched it eagerly, tracking the evolution of its light curve; the shape that light intensity forms on a graph over time. They had to stop after about 70 days because the afterglow moved behind the Sun, but should reappear around now.
In a paper led by Maya Williams of Pennsylvania State University, a team of astronomers found that GRB 221009A’s near-explosion X-ray afterglow was the brightest ever detected by the Swift Observatory by an order of magnitude. In simulations of randomly generated bursts, only one in 10,000 was as powerful as GRB 221009A.
Given the distance, the brightness of GRB 221009A matched the brightness of other gamma-ray bursts in the Swift catalog.
Others simply appear dimmer because they are farther away. According to the group’s calculations, it is the combination of GRB 221009A’s characteristics that makes it very rare indeed.
“By our estimates,” they write, “gamma-ray bursts as energetic and close as GRB 221009A occur at a frequency of ≲1 per 1,000 years, making this a truly remarkable possibility that is unlikely to be repeated in our lifetime.”
What makes the gamma-ray burst really unusual is the evolution of the afterglow, which doesn’t fit the standard theory.
Gamma-ray bursts are usually accompanied by the glow of electrons moving at near-light speeds. Called synchrotron radiation, it is the result of shocks that form when the initial explosion crashes into the interstellar medium.
GRBs themselves are thought to be composed of energy concentrated in parallel beams that form highly collimated jets. Studying the subsequent synchrotron radiation could help astronomers figure out the shape of the explosion and the jets.
According to Williams and her team, the afterglow suggests that the structure of the GRB 221009A jet is either more complicated than expected, or is not narrowly collimated. The latter scenario, they say, would have major implications for the energy balance of the event.
In another paper led by Tanmoy Laskar of the University of Utah, a team of astronomers suggests that the peculiar afterglow could mean that there is an additional source of synchrotron radiation in the afterglow of the gamma-ray burst, but the consequences could be more serious.
They suggest that the problem may be something fundamentally wrong with the synchrotron afterglow theory.
And a third paper, led by astronomer Manisha Shrestha of the University of Arizona, finds that the afterglow doesn’t contain some of the features you’d expect from a supernova explosion.
They found that this could mean that most of GRB 221009A’s energy budget was spent on emissions, leaving very little evidence to suggest that an exploding star was to blame.
Afterglow It is expected to reappear from behind the Sun this month and is expected to be clearly visible with our telescopes at several wavelengths. Whatever is happening with this strange explosion, astronomers will do their best to understand it.
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