International Team Proposes Nuclei Heavier Than Iron for 240 Quintillion-eV Amaterasu Cosmic Ray
Updated
Updated · Universe Today · May 25
International Team Proposes Nuclei Heavier Than Iron for 240 Quintillion-eV Amaterasu Cosmic Ray
2 articles · Updated · Universe Today · May 25
A new Physical Review Letters study argues some ultrahigh-energy cosmic rays may be ultraheavy atomic nuclei, offering a possible explanation for the 2021 Amaterasu particle detected in Utah.
Simulations showed nuclei heavier than iron lose energy more slowly than protons or lighter nuclei in intergalactic space, making them more likely to survive cosmic distances and reach Earth at extreme energies.
The Amaterasu event carried about 240 x 10^18 electron volts—among the most powerful ever observed—yet its inferred arrival direction points to a cosmic void with no obvious source.
The team says likely accelerators include black-hole-forming stellar collapses, magnetars and neutron-star mergers, and predicts future observations should find a composition heavier than iron if the idea is correct.
Researchers hope next-generation observatories including AugerPrime and the proposed Global Cosmic Ray Observatory can test whether ultraheavy nuclei account for the highest-energy cosmic-ray events.
Is the universe's most powerful particle a heavy element from a dead star, or an exotic relic from the dawn of time?
What monster engine, hiding in an empty cosmic void, is firing these impossibly energetic particles across the universe?
The 240 EeV Amaterasu Particle: Challenges and Breakthroughs in Ultrahigh-Energy Cosmic Ray Research
Overview
In May 2021, the Telescope Array in Utah detected the Amaterasu particle, one of the most energetic cosmic rays ever observed. Its discovery, published in Science, has puzzled astrophysicists because its extreme energy challenges current ideas about where such particles come from. The particle appeared to arrive from the Local Void, a region with no known sources powerful enough to create it, deepening the mystery. This unexpected finding has led scientists to expand the Telescope Array, hoping that capturing more of these rare events will help reveal the true origins and nature of these extraordinary cosmic rays.