Observation of a Large-scale Anisotropy in the Arrival Directions of Cosmic Rays above 8x10^18 eV

THE PIERRE AUGER COLLABORATION.; S. J. SCIUTTO

SCIENCE

AMER ASSOC ADVANCEMENT SCIENCE

Año: 2017 vol. 357 p. 1266 - 1270

0036-8075

Cosmic rays are atomic nuclei arriving from outer space that reach the highest energiesobserved in nature. Clues to their origin come from studying the distribution of theirarrival directions. Using 3 × 104 cosmic rays with energies above 8 × 1018 electronvolts, recorded with the Pierre Auger Observatory from a total exposure of 76,800 km2sr year, we determined the existence of anisotropy in arrival directions. The anisotropy,detected at more than a 5.2s level of significance, can be described by a dipole with anamplitude of 6:5þ1:30:9 percent toward right ascension ad = 100 ± 10 degrees and declinationdd = 24þ1213 degrees. That direction indicates an extragalactic origin for these ultrahighenergyparticles.