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Large-scale cosmic-ray anisotropies above 4 EeV measured by the Pierre Auger Observatory
- Source :
- ApJ 868 (2018) 4
- Publication Year :
- 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 $E\geq 8$ 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 $\beta=0.79\pm 0.19$. 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.<br />Comment: Published version, 16 pages, 7 figures, 8 tables
- Subjects :
- Astrophysics - High Energy Astrophysical Phenomena
Subjects
Details
- Database :
- arXiv
- Journal :
- ApJ 868 (2018) 4
- Publication Type :
- Report
- Accession number :
- edsarx.1808.03579
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.3847/1538-4357/aae689