Arrival Directions of Cosmic Rays above 32 EeV from Phase One of the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION; MOLLERACH, SILVIA

Astrophysical Journal

Institute of Physics

Año: 2020 vol. 935

A promising energy range to look for angular correlations between cosmic rays of extragalactic origin and theirsources is at the highest energies, above a few tens of EeV (1 EeV ≡ 10 18 eV). Despite the flux of these particlesbeing extremely low, the area of ∼3000 km 2 covered at the Pierre Auger Observatory, and the 17 yr data-takingperiod of the Phase 1 of its operations, have enabled us to measure the arrival directions of more than 2600 ultra-high-energy cosmic rays above 32 EeV. We publish this data set, the largest available at such energies from anintegrated exposure of 122,000 km 2 sr yr, and search it for anisotropies over the 3.4π steradians covered with theObservatory. Evidence for a deviation in excess of isotropy at intermediate angular scales, with ∼15° Gaussianspread or ∼25° top-hat radius, is obtained at the 4σ significance level for cosmic-ray energies above ∼40 EeV.