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SALT LAKE CITY — Space scientists seeking to unravel the mysterious origins of powerful cosmic rays have detected an extremely rare, ultra-high-energy particle that may have come to Earth from beyond the Milky Way.
According to the authors, the energy of these particles is invisible to the naked eye and is equivalent to dropping a brick from waist height onto your toes. new research It was published Thursday in the journal Science. The study found that this is comparable to the single most energetic cosmic ray ever observed, which was detected in 1991.
Cosmic rays are charged particles that travel through space and constantly fall on Earth. Although the sun sometimes emits low-energy cosmic rays, very high-energy cosmic rays are an exception. They are believed to come to Earth from other galaxies and extragalactic sources.
“When you hold your hand out, one[cosmic ray]passes through your palm every second, and they’re really low energy,” said study co-author John Matthews, a research professor at the University of Utah.
“When you’re exposed to these very high-energy (cosmic rays), that’s the equivalent of one ray per square kilometer per century. It would never pass through human hands.”
Despite years of research, the exact origin of these high-energy particles is still unclear. They are thought to be associated with some of the most energetic phenomena in the universe, such as black holes, gamma-ray bursts, and phenomena involving active galactic nuclei, but the largest discovered so far have been associated with intense celestial bodies. It seems to originate from a cavity or empty space that is not affected by the . An event was held.
Tracing high-energy cosmic rays
The recently discovered particle, called the Amaterasu particle after the sun goddess in Japanese mythology, was discovered by a cosmic ray observatory in Utah’s West Desert known as the Telescope Array.
The telescope array, which began operating in 2008, consists of 507 ping pong table-sized surface detectors covering 270 square miles. More than 30 ultra-high-energy cosmic rays were observed, but on May 27, 2021, they collided with the atmosphere above Utah, raining secondary particles to the ground, and were larger than the Amaterasu particle detected by the detector. It is said that there was no such thing. the study.
“We can see how many particles hit each detector, and that tells us how energetic the primary cosmic rays are,” Matthews said.
The event activated 23 surface detectors, and its energy was calculated to be about 244 exaelectronvolts. Detected over 30 years ago, the most energetic cosmic ray ever observed was 320 exaelectronvolts.
For reference, 1 exaelectronvolt is equivalent to 1 billion gigaelectronvolts, and 1 gigaelectronvolt is equal to 1 billion electronvolts. Then the Amaterasu particle would be 244,000,000,000,000,000,000 electron volts. By comparison, the typical energy of an electron in a polar aurora is 40,000 electron volts. According to NASA.
Ultra-high-energy cosmic rays carry tens of millions of times more energy than particle accelerators such as artificial particle accelerators. Large Hadron Colliderthe most powerful accelerator ever built, explained Glennys Farrar, a physics professor at New York University.
“What is needed is a region of very high magnetic field, something like a super-large LHC, but natural. And the conditions required are so exceptional that the magnetic field source are extremely rare, and the particles are scattered across the vastness of space. The chances of them hitting Earth are extremely low,” Farrar, who was not involved in the study, said in an email.
The atmosphere primarily protects humans from the harmful effects of cosmic rays. Sometimes it can cause computer problems. Particles, and space radiation more broadly, can cause structural damage to DNA and alter many cellular processes, posing significant risks to astronauts. According to NASA.
mysterious sauce
The source of these ultra-high-energy particles has puzzled scientists.
Matthews, co-spokesperson for the Telescope Array Collaboration, said the two largest cosmic rays recorded appeared to be “somewhat random.” Tracing its trajectory back, there appears to be nothing energetic enough to produce such a particle. Specifically, the Amaterasu particles appear to originate from what is known as the local void, a region of space in the sky adjacent to the Milky Way.
“If you take the two highest-energy events, the events we just discovered, the (1991) particles, they don’t even seem to point to anything. It must be something relatively close. “Anything that’s really massive and really violent that astronomers with visible telescopes can’t see,” Matthews said.
“It’s coming from an area that looks like a localized empty space. It’s a cavity. So what the heck is going on?”
Expanding the Telescope Array may provide some answers. Once completed, the 500 new detectors will enable the telescope array to capture cosmic ray-induced particle showers spanning 1,120 square miles. rhode islandaccording to a statement from the University of Utah.