Telescope in Utah detects mysterious cosmic ray beyond our galaxy

• Scientists in Utah have identified a rare cosmic ray believed to have come from beyond the Milky Way.
• It has been named the "Amaterasu particle," after the Japanese sun goddess.
• A Telescope Array spokesperson called the particle's source a "mystery."

Space scientists from the University of Utah and the University of Tokyo have identified an exceedingly rare, ultra-high-energy cosmic ray believed to have traveled from beyond the Milky Way galaxy.

Named the "Amaterasu particle" after the Japanese sun goddess, it is a subatomic entity, invisible to the naked eye.

The findings, published in the journal Science, reveal its energy rivals the record-setting "Oh-My-God" particle observed in 1991.

John Matthews, Telescope Array co-spokesperson and co-author of the study, said: "In the case of the Oh-My-God particle and this new particle, you trace its trajectory to its source and there's nothing high energy enough to have produced it. That's the mystery of this — what the heck is going on?"

Cosmic rays, charged particles constantly showering Earth, typically originate from the sun. However, high-energy cosmic rays, like the Amaterasu particle, are exceptional and are thought to come from other galaxies and extragalactic sources.

The recently discovered particle was identified by the Telescope Array, an observatory in Utah's West Desert. The space observation station, comprising 507 surface detectors over 270 square miles, observed more than 30 ultra-high-energy cosmic rays, with the Amaterasu particle standing out as the most significant event.  

Striking the atmosphere on May 27, 2021, it triggered 23 surface detectors, with an energy calculation of about 244 exa-electron volts, just shy of the "Oh-My-God" particle's 320 exa-electron volts.

The observed particles, including the Amaterasu particle, seem to emerge from voids or empty space.

Unlike low-energy cosmic rays, whose origins are traceable, ultra-high-energy particles like this appear to come from seemingly empty spaces. The Amaterasu particle is believed to originate from the Local Void, an empty region bordering the Milky Way galaxy.

The Telescope Array's expansion offers hope for more answers to this rare event. With an additional 500 detectors covering an extensive area nearly the size of Rhode Island, the observatory aims to capture cosmic ray-induced particle showers and provide further insights into cosmic mysteries.