The cosmos is the stage for a variety of giant explosions. These include stellar flares, where stars suddenly release magnetic energy; and neutron star mergers, where two dense stars collide together. But one class of explosions outshines the rest: Gamma ray bursts are the most energetic explosions seen in the universe.
Gamma rays are one of the most energetic forms of light, and gamma ray bursts release almost unimaginable quantities of them. First discovered during the Cold War – by military satellites searching for the signs of nuclear tests in the upper atmosphere – gamma ray bursts are now thought to be caused by massive stars undergoing huge explosions when they run out of fuel. These events are rare, but so energetic they can be seen in galaxies many billions of light years away.
Recently, astronomers thought they had seen evidence for one of these explosions from the most distant galaxy every seen. But a recently published paper casts doubt on these claims, suggesting it might have been caused by a more mundane source much closer to home.
Gamma ray bursts
No gamma ray bursts have been documented in our galaxy yet, which may not be a bad thing. A gamma ray burst pointed directly at the Earth would probably lead to a mass extinction event, and the end of civilisation as we know it. Undocumented events may in fact already have caused mass extinction events in Earth’s history.
Gamma ray bursts have been seen far away, however. The paper suggesting researchers had discovered a new gamma ray burst in the most distant known galaxy was published in 2020. Using the Keck telescope on Mauna Kea, Hawaii, the researchers observed strips of the sky, and happened to see a bright flash, just a few seconds long, in one of their exposures.
By modelling the duration and brightness of the flash, they ruled out the possibility that it was a natural or human-made satellite close to home. They also ruled out a number of other astronomical explanations, and concluded that the most likely explanation was, indeed, a gamma ray burst.
What was so unique about this discovery was that the team pinpointed the direction of the event and found it was coming from the same area as a galaxy known as GN-z11, which just so happens to be the most distant and oldest galaxy we’ve yet discovered.
Was this an incredible cosmic coincidence? Or was this a sign that gamma ray bursts were more common in the very early universe, just 400 million years after the big bang? The latter conclusion would have big implications for our understanding of how stars and galaxies form in the early universe, and led to a lot of excitement among astronomers.
The cosmos is the stage for a variety of giant explosions. These include stellar flares, where stars suddenly release magnetic energy; and neutron star mergers, where two dense stars collide together. But one class of explosions outshines the rest: Gamma ray bursts are the most energetic explosions seen in the universe.
Gamma rays are one of the most energetic forms of light, and gamma ray bursts release almost unimaginable quantities of them. First discovered during the Cold War – by military satellites searching for the signs of nuclear tests in the upper atmosphere – gamma ray bursts are now thought to be caused by massive stars undergoing huge explosions when they run out of fuel. These events are rare, but so energetic they can be seen in galaxies many billions of light years away.
Recently, astronomers thought they had seen evidence for one of these explosions from the most distant galaxy every seen. But a recently published paper casts doubt on these claims, suggesting it might have been caused by a more mundane source much closer to home.
Gamma ray bursts
No gamma ray bursts have been documented in our galaxy yet, which may not be a bad thing. A gamma ray burst pointed directly at the Earth would probably lead to a mass extinction event, and the end of civilisation as we know it. Undocumented events may in fact already have caused mass extinction events in Earth’s history.
Gamma ray bursts have been seen far away, however. The paper suggesting researchers had discovered a new gamma ray burst in the most distant known galaxy was published in 2020. Using the Keck telescope on Mauna Kea, Hawaii, the researchers observed strips of the sky, and happened to see a bright flash, just a few seconds long, in one of their exposures.
By modelling the duration and brightness of the flash, they ruled out the possibility that it was a natural or human-made satellite close to home. They also ruled out a number of other astronomical explanations, and concluded that the most likely explanation was, indeed, a gamma ray burst.
What was so unique about this discovery was that the team pinpointed the direction of the event and found it was coming from the same area as a galaxy known as GN-z11, which just so happens to be the most distant and oldest galaxy we’ve yet discovered.
Was this an incredible cosmic coincidence? Or was this a sign that gamma ray bursts were more common in the very early universe, just 400 million years after the big bang? The latter conclusion would have big implications for our understanding of how stars and galaxies form in the early universe, and led to a lot of excitement among astronomers.
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