A Century-Old Mystery Unveiled: The Most Energetic Particles to Reach Earth Come From Outside the Milky Way, The Auger Group at KICP
Cosmic rays are energetic subatomic particles from space that can have energies 10 million times greater than those created by man-made particle accelerators. Their origin has been a mystery for almost a century, ever since their discovery in 1912. The Pierre Auger Observatory in Argentina, an international effort involving 17 countries and hundreds of scientists, including an active group at KICP led by Auger Spokesperson Emeritus James Cronin and faculty members Angela Olinto and Paolo Privitera, has recently measured the arrival directions of the highest energy cosmic rays. The pattern in the sky created by these particles reveals that the most energetic particles do not come from every direction in space. Instead, their arrival directions trace the sky distribution of the most energetic galaxies in our neighborhood of the Universe, the suburbs around our Milky Way Galaxy - galaxies that are suspected of harboring active supermassive black holes at their centers. [more]
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