Interesting article in the October 2016 issue of the American bi-weekly magazine ScienceNews.
Cosmic rays are mostly charged particles that reach Earth from outer space.
The Pierre Auger Collaboration has investigated the constraining power of the cosmic ray spectrum and composition measurements with respect to the properties of the possible sources.
The Pierre Auger Collaboration has searched for the possible presence of photons with energies exceeding 1018 eV in the flux of cosmic rays arriving at Earth.
When an ultrahigh-energy cosmic ray impacts the Earth’s atmosphere, it can generate an enormous cascade of billions of energetic particles capable of reaching the ground.