Scientists Baffled by Origins of Powerful ‘Cosmic Ray’ Discovered in Distant Space

A screengrab from a video shows an artist's illustration of the extremely energetic cosmic ray observed by the Telescope Array Collaboration led by the University of Utah and the University of Tokyo. It's been named the "Amaterasu particle." Osaka Metropolitan University/L-INSIGHT, Kyoto University/Ryuunosuke Takeshige

Scientists have detected something extremely rare—the second most powerful cosmic ray ever recorded—but the discovery has left them baffled as to where exactly it came from.

A team of researchers, led by Associate Professor Toshihiro Fujii from the Graduate School of Science, along with researchers from the Nambu Yoichiro Institute of Theoretical and Experimental Physics at Osaka Metropolitan University, and the University of Utah, documented their findings, which are set to be published in Science on Nov. 24.

The recently discovered particle has been nicknamed the “Amaterasu” particle, after the sun goddess that, according to Shinto beliefs, was instrumental in the creation of Japan.

It was discovered by a cosmic ray observatory in Utah’s West Desert known as the Telescope Array, which is comprised of more than 500 “surface detector stations” spread out across 270 square miles.

Mr. Fujii and the international team of scientists have been conducting the Telescope Array experiment since 2008 but the newly-discovered high-energy particle was detected on May 21, 2021, when it triggered 23 of those detectors.

With a calculated energy level of about 244 exa-electron volts (EeV), it is the second-highest extreme-energy cosmic ray ever seen after the “Oh-My-God” particle, which had an estimated energy of 320 EeV and was detected in 1991 via the University of Utah Fly’s Eye experiment.

According to researchers, “Amaterasu” has a force that is equivalent to dropping a brick on your toe from waist height.

However, scientists are perplexed as to exactly where the rare phenomenon came from, although they believe its arrival was from the direction of a void, an empty area of space bordering the Milky Way galaxy.

‘Energy Level Unprecedented’

“When I first discovered this ultra-high-energy cosmic ray, I thought there must have been a mistake, as it showed an energy level unprecedented in the last 3 decades,” Mr. Fujii said in a press release.

“No promising astronomical object matching the direction from which the cosmic ray arrived has been identified, suggesting possibilities of unknown astronomical phenomena and novel physical origins beyond the Standard Model,” he continued.

Mr. Fujii said his team remains committed to the Telescope Array experiment and plans to conduct “a more detailed investigation into the source of this newly discovered extremely energetic particle.”

Cosmic rays are energetic charged particles that move through space at nearly the speed of light, according to NASA. The charged particles are made up of a wide range of energies consisting of positive protons, negative electrons, or entire atomic nuclei and rain down onto Earth nearly constantly.

While many cosmic rays, particularly at low energies, are produced by the sun, the origins of those at higher energies are still relatively unknown, although evidence suggests that some may be made in the Milky Way in supernova remnants, effectively the structure that results in the aftermath of an explosion of a star in a supernova.

Researchers ultimately believe the recently discovered cosmic ray may follow particle physics unknown to science.

These events seem like they’re coming from completely different places in the sky. It’s not like there’s one mysterious source,“ said John Belz, professor at the University of Utah and co-author of the study. ”It could be defects in the structure of spacetime, colliding cosmic strings. I mean, I’m just spit-balling crazy ideas that people are coming up with because there’s not a conventional explanation.”