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Rare Ultra-High-Energy Cosmic Ray Detected in Utah Originating Beyond Milky Way Galaxy

Scientists studying cosmic rays have identified an exceptionally rare, ultra-high-energy particle that they believe originated from beyond the Milky Way galaxy. The discovery, named the Amaterasu particle, was made by a cosmic ray observatory called the Telescope Array in Utah’s West Desert. This subatomic particle, with energy equivalent to dropping a brick from waist height, is comparable to the most energetic cosmic ray ever observed, known as the “Oh-My-God” particle.

Cosmic rays, charged particles constantly raining down on Earth, include low-energy ones from the sun and exceptionally high-energy particles believed to come from other galaxies and extragalactic sources. The origins of these high-energy particles remain unclear, with theories linking them to phenomena like black holes and gamma-ray bursts.

The Amaterasu particle, detected in May 2021, struck the Earth’s atmosphere above Utah, triggering 23 surface detectors with a calculated energy of about 244 extra-electron volts. The Local Void, an empty space bordering the Milky Way, was identified as its possible source. Despite years of research, scientists struggle to pinpoint the origins of these ultra-high-energy particles, which carry millions of times more energy than human-made particle accelerators.

The Telescope Array, consisting of 507 surface detectors covering 700 square kilometers, observed the Amaterasu particle and aims to expand further to capture cosmic ray-induced particle showers across a larger area. Studying these cosmic rays provides insights into the most energetic phenomena in the universe, with potential applications in understanding space radiation’s impact on technology and astronauts.