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.
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.A., 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., et al.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - 868:1(2018), p. 4. [10.3847/1538-4357/aae689]
Large-scale Cosmic-Ray Anisotropies above 4 EeV Measured by the Pierre Auger Observatory
Aramo, C.Membro del Collaboration Group
;Barbato, F.Membro del Collaboration Group
;Colalillo, R.Membro del Collaboration Group
;Guarino, F.Membro del Collaboration Group
;Valore, L.Membro del Collaboration Group
;Yushkov, A.;
2018
Abstract
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
