- Scientists in Utah have identified a rare cosmic ray that could've come from beyond the Milky Way.
- It has been named the "Amaterasu particle" after the Japanese sun goddess.
Space scientists from the University of Utah and the University of Tokyo have identified an exceedingly rare, ultra-high-energy cosmic ray believed to originate 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, show that its energy rivals the record-setting Oh-My-God particle observed in 1991.
John Matthews, a spokesperson for Telescope Array and the coauthor 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. But high-energy cosmic rays such as the Amaterasu particle are exceptional and are thought to come from other galaxies and extragalactic sources.
Telescope Array, an observatory in Utah's West Desert, identified the particle. 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.
The Amaterasu particle struck the atmosphere on May 27, 2021, triggering 23 surface detectors and giving off energy equaling 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 such as this appear to come from seemingly empty spaces. The Amaterasu particle is believed to originate from the Local Void, an empty region of space bordering the Milky Way galaxy.
Telescope Array's expansion offers hope for more answers to this phenomenon. 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 other cosmic mysteries.