Scientists of the international Pierre Auger Collaboration that included a University of Colorado at Boulder co-author have found that active galactic nuclei, thought to be powered by black holes, are the most likely candidate for the source of the highest-energy cosmic rays that hit Earth.
Using the Pierre Auger Observatory in Argentina, the largest cosmic-ray observatory in the world, a team of scientists from 17 countries found that the sources of the highest-energy particles are not distributed uniformly across the sky. Instead, the Auger results link the origins of these mysterious particles to the locations of nearby galaxies that have active nuclei in their centers.
The results appear in the Nov. 9 issue of the journal Science.
CU-Boulder researcher Jeff Brack of the physics department, who also is a Colorado State University research affiliate, was a co-author on the paper.
"This is a major, major result," said CU-Boulder physics Professor Uriel Nauenberg, a senior member of CU-Boulder's High Energy Physics Group who was not involved in the study. "It solves one of the mysteries of the source of cosmic rays that has been with us for 80 years."
Nauenberg said the new discovery "heightens the chances" that a proposed sister facility of the Pierre Auger Observatory in Argentina will be built in the Northern Hemisphere near Lamar, Colo., in the coming years.
Active Galactic Nuclei are thought to be powered by supermassive black holes that are devouring large amounts of matter. They have long been considered sites where high-energy particle production might take place. They swallow gas, dust and other matter from their host galaxies and spew out particles and energy.
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