In a groundbreaking discovery, space scientists have detected a remarkably high-energy subatomic particle believed to have journeyed to Earth from beyond our Milky Way galaxy. This extraordinary find promises to provide valuable insights into the enigmatic origins of cosmic rays, offering a tantalizing glimpse into the extreme phenomena shaping our universe.
The Astonishing Discovery The energy of this subatomic particle, which eludes the naked eye, equates to the sensation of dropping a brick onto your toe from waist height—an experience captured by the authors of a recently published study in the journal Science. This particle’s energy level places it in the same league as the single most energetic cosmic ray ever observed, the legendary “Oh-My-God” particle identified in 1991.
Cosmic rays, consisting of charged particles, continuously traverse space and shower Earth. While low-energy cosmic rays often originate from the sun, their ultra-high-energy counterparts are exceptionally rare and are believed to originate beyond our galaxy, emanating from other galaxies and extragalactic sources.
The Rarity of Ultra-High-Energy Cosmic Rays Study coauthor John Matthews, a research professor at the University of Utah, offered perspective on the scarcity of these ultra-high-energy cosmic rays. He likened it to a scenario where, if you were to extend your hand, only one of these particles would pass through the palm of your hand every second. However, these are low-energy occurrences. In contrast, when it comes to ultra-high-energy cosmic rays, it becomes an exceedingly rare phenomenon, more akin to one such particle traversing through an entire square kilometer every century.
Unveiling the Cosmic Guest This elusive particle, affectionately dubbed the “Amaterasu particle” after the sun goddess in Japanese mythology, was stumbled upon by a cosmic ray observatory nestled in Utah’s West Desert—the Telescope Array. This observatory, operational since 2008, comprises 507 surface detectors roughly the size of ping-pong tables, collectively spanning an area of 700 square kilometers (270 square miles).
The Amaterasu particle’s cosmic debut occurred on May 27, 2021, as it pierced Earth’s atmosphere above Utah. Upon entry, it gave rise to secondary particles that eventually made their way to the ground, where the observatory’s detectors eagerly captured their presence. The detectors’ meticulous recordings enabled scientists to gauge the primary cosmic ray’s energy.
Unlocking Cosmic Energies This extraordinary event triggered 23 of the observatory’s surface detectors, signaling an estimated energy level of approximately 244 exa-electron volts. To put this into perspective, the renowned “Oh My God particle” detected over three decades ago possessed an energy level of 320 exa-electron volts.
For clarity, 1 exa-electron volt equals 1 billion gigaelectron-volts, and 1 gigaelectron volt equals 1 billion electron volts. By this scale, the Amaterasu particle boasts an astonishing energy level of 244 quintillion electron volts. To contrast, the typical energy of an electron in the polar aurora is a mere 40,000 electron volts, as indicated by NASA.
Conclusion The discovery of the Amaterasu particle offers a rare glimpse into the cosmic realm’s mysteries, shedding light on the enigmatic origins of ultra-high-energy cosmic rays. As scientists delve deeper into the cosmos, these cosmic messengers from beyond our galaxy continue to captivate our imagination, inspiring further exploration and understanding of the universe’s most profound secrets.