Large-scale cosmic-ray anisotropies above 4 EeV measured by the Pierre Auger Observatory

• Autores: Calcagni, Laura Randa; Dova, María Teresa; Hansen, Patricia María; Mariazzi, Analisa Gabriela; Sciutto, Sergio Juan; Tueros, Matías Jorge; Vergara Quispe, Indira Dajhana; Wahlberg, Hernán Pablo; The Pierre Auger Collaboration
• Año de publicación: 2018
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Física; Cosmic ray; Physics; Dipole; Amplitude; Pierre auger observatory; Context (language use); Astrophysics; Cosmic cancer database; Right ascension; Anisotropy; Observatory; Auger; Astroparticle physics
• Institución: Universidad Nacional de La Plata

We present a detailed study of the large-scale anisotropies of cosmic rays with energies above 4 EeV measured using the Pierre Auger Observatory. For the energy bins [4,8] EeV and E ≥ 8 EeV, the most significant signal is a dipolar modulation in right ascension at energies above 8 EeV, as previously reported. In this paper we further scrutinize the highest-energy bin by splitting it into three energy ranges. We find that the amplitude of the dipole increases with energy above 4 EeV. The growth can be fitted with a power law with index β=0.79 ± 0.19. The directions of the dipoles are consistent with an extragalactic origin of these anisotropies at all the energies considered. Additionally we have estimated the quadrupolar components of the anisotropy: they are not statistically significant. We discuss the results in the context of the predictions from different models for the distribution of ultrahigh-energy sources and cosmic magnetic fields.
Instituto de Física La Plata