Some of the space radiation that collides with the Earth has an explosive origin.
Astronomers discovered the wreckage of A Supernova An explosion potentially capable of shooting down high-energy particles – or cosmic rays – that bombard the ground frequently.
Their new findings link shock waves and debris from dying stars with high-energy natural proton accelerators in space, called PeVatrons. These intriguing cosmic accelerators — named for their ability to increase the energy of particles to extreme beta-electronvolts (PeV) levels — have not been conclusively identified.
A handful of suspected PeVatrons had already been identified before this study, including one in our center Milky Waygalaxy. The research team says their new discovery of the remnants of a supernova explosion – a cloud of a substance called G106.3 + 2.7 – may be the most promising candidate so far.
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The debris is located 2,600 light-years from Earth, has a comet-like shape and has luster pulsar A high-spin magnetic neutron star at one end.
Since neutron stars form when stars undergo gravitational collapse, which also triggers supernovae, researchers have reason to believe that the pulsar’s debris cloud and supernova were created by the same violent event.
Using NASA’s Fermi Large Area Telescope, astronomers have detected a high-energy gamma-ray glow that suggests G106.3 + 2.7 may be capable of the PeVatron-related feat of detonating particles with energies equivalent to one million billion electron volts – 10 times greater than the energies generated. About Large Hadron ColliderThe most powerful particle accelerator on Earth.
“Theorists believe that the most energetic cosmic ray protons in the Milky Way are up to one million billion electron volts, or PV energies,” said Qi Fang, associate professor of physics at the University of Wisconsin at Madison. statement (Opens in a new tab) “It was difficult to determine the exact nature of their sources, which we call the Biphatron.”
Scientists believe that supernova debris from dead stars accelerates particles to such high energies when magnetic fields around them trap charged particles. This process allows shock waves from the supernova to shake the trapped particles repeatedly, increasing their energy each time. Finally, the particles are so energetic that supernova remnants cannot hold them, and the particles escape into space at speeds close to light like cosmic rays.
It was difficult to trace cosmic rays to the supernova debris because the protons that make up the cosmic rays are electrically charged. So cosmic rays are likely to be scattered when they interact with magnetic fields during their journey through space. So astronomers cannot easily tell which direction the rays are coming from when they finally reach our planet.
However, since accelerating protons to such high speeds causes the emission of gamma rays, this high-energy light can be a good indicator for detecting the source of cosmic rays.
Related: The most powerful cosmic rays come from galaxies very far away
The Fermi and the Very Active Imaging Radiometer Telescope Array System (VERITAS) at the Fred Lawrence Whipple Observatory in southern Arizona detected gamma rays coming from within the tail of the G106.3+2.7 supernova debris. In addition, other observatories have found high-energy photons from the same region, indicating that it could indeed be PeVatron.
“This object has been a source of great interest for some time now, but to be crowned as PeVatron, we had to prove that it speeds up protons,” Researcher Henrike Fleischhack from NASA Goddard Space Flight Centerin Greenbelt, Maryland.
“What is important 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 believe we’ve established that G106.3 + 2.7 is indeed a PeVatron.”
To analyze gamma rays from the comet-shaped cloud, the team first had to calculate a pulsar – called J2229 + 6114 – that emits its own gamma rays as it rapidly rotates. Because high-energy light is only emitted toward Earth during half of the pulsar’s rotation period, the researchers simply ignored gamma-ray emissions during that period.
The G106.3 + 2.7 tail appears to emit a few gamma photons with energies below 10 gigaelectronvolts (GeV); Above this reference, the effect of the pulsar was minimal. The absence of gamma rays below 10 GeV also indicated that the detected emission was not caused by accelerating electrons.
This discovery led the researchers to conclude that the source of some of the gamma rays from G106.3 + 2.7 was indeed accelerating protons to energies at the PeV level.
“So far, G106.3 + 2.7 is unique, but it could turn out to be the brightest member of a new group of supernova remnants that emit gamma rays up to TeV energies,” Fang said. “More of these observations could be detected by future observations from Fermi and high-energy gamma-ray observatories.”
The team’s findings are discussed in an article published in the August 10 issue of the journal. Physical examination letters. (Opens in a new tab)
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