Astronomers have just detected what could be the most powerful flash of light ever seen.
the said gamma burstthe most energetic type of electromagnetic explosion known in the universewas first spotted by telescopes on Sunday (October 9).
Gamma-ray bursts, which were accidentally discovered by US military satellites in the 1960s, are likely produced when giants stars explode at the end of their life before collapsing black holesor when ultra-dense stellar remnants known as neutron stars collide. Within seconds, these explosions release as much energy as the Sun will emit throughout its lifetime of 10 billion years.
The flash detected on Sunday was the most powerful ever observed, releasing 18 teraelectronvolts of energy. Scientists are still analyzing the measurements, but if the results are confirmed, the gamma-ray burst would be the first gamma-ray burst ever found to carry more than 10 teraelectronvolts of energy.
Related: Gamma-ray bursts could be much rarer than we thought, study finds
At first, the strength of the flash confused astronomers; they thought it must have been produced by a relatively close source. They also initially believed that the energy came in X-rays, rather than gamma rays. Subsequent analyzes of the signal confirmed that it was indeed a gamma-ray burst from a source some 2.4 billion Light years a way. Although not exactly close, the gamma-ray burst is still the closest ever seen.
Although this gamma-ray burst is at a safe distance from Earth, a much closer burst would be catastrophic for our planet. Such an energetic flash thousands of light-years away Earth would rob the planet of its protective ozone layer and likely cause a mass extinction. In fact, scientists believe that one of the greatest mass extinction events in Earth’s history – the Ordovician extinction, which happened 450 million years ago – could to have been triggered by such an explosion, according to Nasa (opens in a new tab).
Although the recently spotted gamma-ray burst, dubbed GRB221009A, appeared 20 times closer to Earth than an average gamma-ray burst, it’s still far enough away to cause more excitement than concern.
“It is indeed a very exciting event!” Gemma Anderson, an astronomer at Curtin University in Australia who studies similar phenomena, said ScienceAlert (opens in a new tab). “This event being so close but also very energetic means that the radio, optical, X-ray and gamma light it produces is extremely bright and therefore easy to observe. So we can study this gamma-ray burst with lots of large and small telescopes in around the world and collect very comprehensive datasets as they brighten and then fade.”
Gamma-ray bursts come in two varieties. Short gamma-ray bursts are rarer and last no more than two seconds. These bursts represent about 30% of all these events and are thought to be caused by neutron star collisions. The other type, long gamma-ray bursts, can last up to several minutes and are probably produced by hypernovastellar explosions 100 times brighter than supernovaein which supermassive stars die after running out of hydrogen in their cores.
Astronomers mainly see the afterglow of these explosions which comes from the electrons fueled by the explosion. GRB221009A appears to be a long gamma-ray burst, but astronomers don’t yet know what caused it.
“It’s still too early to tell,” Anderson told ScienceAlert. “The light from an underlying supernova will take days to clear. However, given the long duration of this gamma-ray burst, it can be a very powerful type of supernova.”
Telescopes around the world (and in Earth orbit) are now pointing to the dusty dust galaxy where the lightning came from. They will try to observe the light generated by the explosion in as many wavelengths as possible to get the most complete picture of its origin.
“When you’re dealing with cosmic explosions that blast stellar remnants apart at near light speed, leaving a black hole behind, you’re watching physics happen in the most extreme environments that are impossible to recreate on Earth.” , Anderson told ScienceAlert. “We still don’t fully understand this process. Such a nearby explosion means we can collect very high quality data to study and understand how such explosions occur.”
The observations were first published in the Astronomer’s Telegram (opens in a new tab) Sunday, October 9.
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