High-Energy Cosmic Rays Tracked to the Source

Findings from the Pierre Auger Observatory in Argentina have helped pinpoint the source of ultra-high energy cosmic rays, which are the most energetic particles known in the universe. A single ultra-high energy proton has as much energy upon collision with the atmosphere as a fast-pitched baseball or a 100-km/hr tennis ball serve. The protons and atomic nuclei in this energy range bombard the Earth and provide fertile ground for speculation about the origins.

The sources found indicate support for the "active galactic nuclei" theory, which is that the ultra-high energy cosmic rays come from supermassive black holes found at the center of galaxies. The exact mechanism by which the particles result in such highly energetic accelerations is still a mystery, however.

• Science - Universe's Highest-Energy Particles Traced Back to Other Galaxies and Correlation of the Highest-Energy Cosmic Rays with Nearby Extragalactic Objects.
• Pierre Auger Observatory - Auger Observatory closes in on long standing mystery, links highest-energy cosmic rays with violent black holes
• Nature - Supermassive black-hole galaxies spin out super-energetic particles
• Science News - Ray Tracing: Energetic cosmic rays linked to giant black holes
• New Scientist - Monster black holes power highest-energy cosmic rays