Pierre Auger Observatory

Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory

Cosmic rays are mostly charged particles that  reach Earth from outer space. Although they were discovered more than a century ago, the origin of the ultra-high energy ones (with an energy above 1018 eV, or 100,000 times more energetic than the particles in the LHC beam, the most powerful particle accelerator on Earth) is still a puzzle. The large area of the Pierre Auger Observatory of about 3000 km2 compensates for the low flux of such particles and allows us to search for an excess/deficit of events arriving from different directions in the celestial sphere.


Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory

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.


Search for photons above 10^18 eV with the hybrid detector of the Pierre Auger Observatory

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. These ultra-high energy photons are produced in interactions of the charged cosmic rays with energies close to 1020 eV with the cosmic microwave background (GZK effect).