Ever since the existence of cosmic rays with individual energies of several Joules was established in the 1960s, speculation has raged as to whether cosmic particles of mean energy of 2 Joules are created in our Milky Way or in distant extragalactic objects.
In a paper that was published in Science on 22 September 2017, the Pierre Auger Collaboration reports observational evidence demonstrating that cosmic rays with energies a million times greater than that of the protons accelerated in the Large Hadron Collider come from much further away than from our own Galaxy.
Observation of a Large-scale Anisotropy in the Arrival Directions of Cosmic Rays above 8×1018eV
The Pierre Auger Collaboration, Science 357 (2017)
[doi: 10.1126/science.aan4338] [arXiv: 1709.07321]
The long Journey of Cosmic Rays
Video by Aurelio Grillo, Pierre Auger Collaboration, and Vincenzo Napolano, INFN Communication Office.
Courtesy of Italian Institute for Nuclear Physics – INFN