Large-scale Cosmic-Ray Anisotropies above 4 EeV Measured by the Pierre Auger Observatory

AAB, A.; ABREU, P.; AGLIETTA, M.; ALBUQUERQUE, I.F.M.; ALBURY, J.M.; ALLEKOTTE, I.; ALMELA, A.; CASTILLO, J. ALVAREZ; ALVAREZ-MUÑIZ, J.; ANASTASI, G.A.; ANCHORDOQUI, L.; ANDRADA, B.; ANDRINGA, S.; ARAMO, C.; ASOREY, H.; ASSIS, P.; AVILA, G.; BADESCU, A.M.; BALACEANU, A.; BARBATO, F.; LUZ, R. J. BARREIRA; BAUR, S.; BECKER, K.H.; BELLIDO, J.A.; BERAT, C.; BERTAINA, M.E.; BERTOU, X.; BIERMANN, P.L.; BITEAU, J.; BLAESS, S.G.; BLANCO, A.; BLAZEK, J.; BLEVE, C.; BOHÁ?OVÁ, M.; BONIFAZI, C.; BORODAI, N.; BOTTI, A.M.; BRACK, J.; BRETZ, T.; BRIDGEMAN, A.; BRIECHLE, F.L.; BUCHHOLZ, P.; BUENO, A.; BUITINK, S.; BUSCEMI, M.; CABALLERO-MORA, K.S.; CACCIANIGA, L.; CALCAGNI, L.; CANCIO, A.; CANFORA, F.; CARCELLER, J.M.; CARUSO, R.; CASTELLINA, A.; CATALANI, F.; CATALDI, G.; CAZON, L.; CHINELLATO, J.A.; CHUDOBA, J.; CHYTKA, L.; CLAY, R.W.; CERUTTI, A. C. COBOS; COLALILLO, R.; COLEMAN, A.; COLUCCIA, M.R.; CONCEIÇÃO, R.; CONSOLATI, G.; CONTRERAS, F.; COOPER, M.J.; COUTU, S.; COVAULT, C.E.; DANIEL, B.; DASSO, S.; DAUMILLER, K.; D

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Año: 2018 vol. 868

0004-637X

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 R.A. 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.