Murase Study Identifies Cosmic Rays 40 Million Times LHC Energy as Nuclei Heavier Than Iron
Updated
Updated · Space.com · May 13
Murase Study Identifies Cosmic Rays 40 Million Times LHC Energy as Nuclei Heavier Than Iron
1 articles · Updated · Space.com · May 13
New simulations suggest some ultrahigh-energy cosmic rays are ultraheavy atomic nuclei, not protons, offering a possible solution to a 60-year mystery over how they reach Earth with extreme energies intact.
At energies like the 2021 Amaterasu event—40 million times above Large Hadron Collider collisions—the study found nuclei heavier than iron lose energy more slowly across cosmic distances, making them more likely to survive the trip.
That composition points to exceptionally violent sources capable of forging and accelerating such nuclei, including massive star collapses into black holes or magnetized neutron stars and binary neutron-star mergers.
The Physical Review Letters paper says a significant ultraheavy component could also help explain differences between northern and southern sky cosmic-ray spectra, a prediction future observations can test by looking for compositions heavier than iron.
Are tiny, ultraheavy nuclei from colliding neutron stars the true origin of the universe's most powerful particles?
Did the Amaterasu particle travel from a distant explosion, or does its 'empty' origin point to entirely new physics?
Ultraheavy Nuclei in Ultrahigh-Energy Cosmic Rays: Implications for Astrophysics and Particle Physics
Overview
A major breakthrough in cosmic ray research has been achieved with Kohta Murase's 2026 study, which reveals that some ultrahigh-energy cosmic rays (UHECRs), including the famous Amaterasu particle, are made of atomic nuclei heavier than iron. This discovery challenges long-standing beliefs about the composition of the universe's most energetic particles and marks a turning point in the field. As a result, scientists are re-evaluating existing models of cosmic ray acceleration and propagation, establishing new constraints on the role of ultraheavy nuclei, and opening new paths to understand the extreme astrophysical environments that produce these powerful cosmic rays.