writes "The Pierre Auger Observatory announced that active galactic nuclei are the most likely candidates for the source of the highest-energy cosmic rays that hit Earth. Using the Southern Pierre Auger Observatory in Argentina, the largest cosmic-ray observatory in the world, spanning over more than 3000 square kilometers, they found that the sources of the highest-energy particles are not distributed uniformly across the sky, linking the origins of these "cosmic bullets" to the locations of nearby galaxies, hosting active nuclei in their centers. These galaxies are thought to be powered by supermassive monster black holes that are devouring large amounts of matter. The exact mechanism of how particles get accelerated to energies 100 million times higher than achievable by the most powerful particle accelerators on Earth is still a mystery. A fraction of recorded events is also available through a public online event display."