Ultra-energetic cosmic ray from unidentified source is falling to Earth
Astronomers have discovered an incredibly high-energy particle falling to Earth from space. It's among the highest-energy cosmic rays ever detected, say scientists. However, the origins of this particle, which is named Amaterasu after the Japanese sun goddess, are a mystery. Experts believe that only the most powerful celestial events can produce such particles. John Matthews, a research professor at the University of Utah, said, "Things that people think of as energetic, like supernova, are nowhere near energetic enough for this."
High-energy cosmic rays are rare to spot
The Amaterasu particle has an energy exceeding 240 exa-electron volts (EeV), millions of times more than what's achieved in the world's most powerful accelerator, Large Hadron Collider. It comes second only to the Oh-My-God particle, another ultra-high-energy cosmic ray—detected in 1991—with 320 EeV energy. Toshihiro Fujii, from Osaka Metropolitan University, Japan, said, "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 three decades."
Telescope Array observatory in Utah spotted the Amaterasu particle
When ultra-high-energy cosmic rays, like Amaterasu, hit Earth's atmosphere, they create a cascade of secondary particles and electromagnetic radiation. Some charged particles in this extensive air shower travel faster than the speed of light. Such particles can be detected by specialized instruments like the Telescope Array observatory in Utah, which found the Amaterasu particle. The Amaterasu particle was found to have emerged from the Local Void, an empty area of space bordering the Milky Way galaxy.
Possible explanations for the mysterious particle
The origin of the Amaterasu particle could indicate a much larger magnetic deflection than predicted or an unidentified source in the Local Void. Interestingly, it could open up new avenues in high-energy particle physics. Prof John Belz, of the University of Utah, said, "These events seem like they're coming from completely different places in the sky. It's not like there's one mysterious source. It could be defects in the structure of spacetime, colliding cosmic strings."
Future investigations and implications
Scientists hope that the Amaterasu particle will lead to further investigations that could help shed light on ultra-high-energy cosmic rays and their origins. Toshihiro Fujii suggested possible explanations such as acceleration by extremely energetic phenomena like gamma-ray bursts or jets from supermassive black holes, or creation in exotic scenarios like the decay of super heavy dark matter. Meanwhile, the team will continue hunting cosmic rays with the upgraded Telescope Array experiment, which boasts four times more sensitivity.
