GRB 220706A gamma-ray burst, Digi Mart USA News: An extremely powerful explosion has been recorded by several satellites orbiting Earth. The radiation from the explosion, designated GRB 220706A, is described in a new study.
The phenomenon is called a gamma-ray burst and is among the most powerful events scientists know of. “These are the most energetic outbursts we have in the universe,” says Unni Fuskeland, chief engineer and researcher at the Institute of Theoretical Astrophysics at the University of Oslo.
Such gamma-ray bursts lasting only a few minutes are estimated to release more energy than our own Sun will emit over its entire lifetime of 10 billion years, according to Space.com. Only a few other known gamma-ray bursts can compare with the explosion described in the new study.
The burst itself lasted many hours, but afterward the explosion continued to emit extremely intense X-ray radiation for as long as 27 days. According to the study, that is far longer than the afterglow of other comparable explosions in space.
The study is available on the international online platform arXiv as a preliminary research article that has not yet been peer-reviewed.
“We have never before seen it last so long,” says Unni Fuskeland. She has reviewed the new research article and assesses it as solid work.
Fuskeland points out that the authors include many researchers with extensive experience in gamma-ray bursts.
Researchers do not know exactly what triggered the gamma-ray burst, but in any case it is an explosion of almost unimaginable strength. Gamma-ray bursts are linked, among other things, to hypernovae, extremely powerful stellar explosions that can occur when a very massive star reaches the end of its life and collapses.
Massive stars are many times heavier than the Sun. When such stars explode, two powerful beams of radiation are emitted in opposite directions from the star’s poles.
These beams consist of gamma radiation, an extremely energetic form of electromagnetic radiation that can travel through space for billions of years.
Earth lay directly in line with the beam from this gamma-ray burst, and the radiation had traveled through space for billions of years before reaching us. We can be glad the explosion occurred so far away.
Had it happened closer, it could have had catastrophic consequences for life on Earth.
Researchers therefore believe the gamma-ray burst may stem from a gigantic stellar explosion, but they cannot yet confirm this with certainty. The burst itself can last from a few seconds to several hours.
The longest are called ultra-long gamma-ray bursts, and the current burst belongs to this category.
After the burst itself follows an afterglow, which can last considerably longer. It is this unusually long-lasting afterglow of X-ray radiation that researchers have now measured.
It lasted several weeks longer than previously expected.
“I also don’t believe X-ray radiation has previously been observed this long after a burst,” says Unni Fuskeland. “No one imagined it could last this long.” The remnants of the explosion thus continued to emit X-ray radiation for weeks, which surprised the researchers.
Researchers simply do not know what causes the prolonged radiation. The research article reviews several possible explanations.
One possibility, for example, is that the remnants of the explosion interact with a disk of extremely hot gas swirling around the collapsed core of the star, Fuskeland explains. This could cause X-ray radiation to be emitted in our direction.
Gamma-ray bursts can be dangerous to Earth, although fortunately that is not the case this time. The explosion occurred so far away that the radiation lost much of its energy, but had it occurred closer, it could have posed a serious threat to life on Earth.
These explosions emit radiation so intense that they could trigger mass extinctions on Earth. It has even been proposed that this may have happened earlier in Earth’s history.
The mass extinction at the end of the Ordovician period, in the Paleozoic era, about 450 million years ago, has been linked to a possible gamma-ray burst, according to this study.
A very long-lasting gamma-ray burst could have struck Earth and partially damaged the ozone layer, which protects us from the Sun’s ultraviolet radiation that could otherwise seriously harm life on Earth. In the most extreme case, a gamma-ray burst could even “sterilize” Earth, according to a 2021 study.
For that to happen, however, the explosion would have to occur relatively close to us, within our own galaxy, and the beam would have to be aimed directly at Earth, which is nearly improbable. The universe is so vast and contains so many stars that Earth is occasionally struck by gamma-ray bursts, but they usually come from distances so great that they cause no harm.
This also applies to GRB 220706A, described in the new study.
Astronomers are not aware of any stars near us that pose an apparent threat. “Astronomers have mapped the systems near us and have found no obvious candidates that could emit gamma-ray bursts.
Fortunately, they are not close enough to cause major damage,” Fuskeland says.
Catastrophic consequences for Earth would require an unusually unlucky alignment. Our planet would have to lie precisely in the path of one of the intense beams emitted from the exploding star.
Source: Forskning.no, translated by Stephanie Lammers-Clark, via Videnskab.dk.
