Some space radiation hitting Earth has an explosive origin.
Astronomers have spotted a wreck supernova explosion that could potentially detonate high-energy particles – or cosmic rays – often bombarding the Earth.
Their new finding links shock waves and debris created by dying stars to natural high-energy proton accelerators in space called PeVatrons. These intriguing cosmic accelerators, named for the particles’ ability to raise their energies to extreme peta-electronvolt (PeV) levels, have never been definitively identified.
A handful of suspect PeVatrons were fingerprinted prior to this study, one of which was at our headquarters. Milky Waygalaxy. The research team says their new findings of the remnants of a supernova explosion (a cloud of material called G106.3+2.7) could be the most promising candidate so far.
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The debris lurks 2,600 light-years from Earth, is comet-shaped and bright pulsar — a highly magnetic spinning neutron star — at one end.
Since neutron stars are formed when stars also undergo gravitational collapse that initiates supernovas, there is good reason for researchers to think that the pulsar and supernova debris cloud were created by the same violent event.
Using NASA’s Fermi Wide Field Telescope, astronomers have detected a high-energy gamma-ray after-beam — implying that G106.3+2.7 may have the ability to blast particles associated with PeVatron at energies equivalent to one million billion electronvolts — by 10 times larger. as the energies produced Large Hadron ColliderThe world’s most powerful particle accelerator.
“Theorists think that the highest-energy cosmic ray protons in the Milky Way reach one million billion electron volts, or PeV energy,” said Ke Fang, assistant professor of physics at the University of Wisconsin, Madison at NASA. Declaration. (opens in new tab) “It has been difficult to pinpoint the precise nature of their source, which we call PeVatrons.”
Scientists suspect that when charged particles are trapped by magnetic fields around them, supernova debris from dead stars accelerates the particles to such high energies. This process allows the shock waves from the supernova to repeatedly hit the trapped particles, increasing their energy each time. Finally, the particles are so energetic that the supernova cannot contain them, and the particles escape into space at close to the speed of light as cosmic rays.
Tracing cosmic rays into supernova debris has been difficult because the protons that make up cosmic rays are electrically charged. Cosmic rays therefore tend to scatter when traveling through space and interacting with magnetic fields. For this reason, astronomers cannot easily tell which direction the rays are coming from when they finally reach our planet.
Since the acceleration of protons to such high velocities causes gamma rays to be emitted, this high-energy light can be a good proxy for detecting the source of cosmic rays.
Related: The Most Powerful Cosmic Rays Coming From Galaxies Far Away
The Very Energetic Radiation Imaging Telescope Array System (VERITAS) at both Fermi and the Fred Lawrence Whipple Observatory in Southern Arizona detected gamma rays through the tail of G106.3+2.7’s supernova debris. Additionally, other observatories have found extremely high-energy photons from the same region, suggesting that it may indeed be a PeVatron.
“This object has been a source of significant interest for some time, but to crown it as a PeVatron, we needed to prove it accelerated protons.” researcher Henrike Fleischhack NASA’s Goddard Space Flight Center“Greenbelt, Maryland,” he said.
“The catch is that electrons accelerated to a few hundred TeV can produce the same emission. Now, with the help of 12 years of Fermi data, we think we have made the case that G106.3+2.7 is indeed a PeVatron.”
To analyze the gamma rays from the comet-shaped cloud, the team first had to take into account the pulsar, called J2229+6114, which emits its own gamma rays as it spins rapidly. Because high-energy light was blasted toward Earth for only half of the pulsar’s rotation period, the researchers ignored gamma-ray emissions during this period.
The tail of G106.3+2.7 emits several gamma-ray photons with energies below 10 Giga-electronvolts (GeV); on this criterion the effect of the pulsar was very small. The absence of gamma rays below 10 GeV also indicated that the detected emissions were not due to accelerating electrons.
This finding led the researchers to conclude that the source of some of the gamma rays from G106.3+2.7 was actually the acceleration of protons to PeV-level energies.
“So far, G106.3+2.7 may turn out to be the brightest member of a new population of supernova remnants that are unique, but emit gamma rays reaching energies of TeV,” Fang said. Said. “More could be revealed by future observations by Fermi and very high-energy gamma-ray observatories.”
The team’s findings are discussed in a paper published in the Aug. Physical Review Letters. (opens in new tab)
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