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Title: Large scale distribution of ultra high energy cosmic rays detected at the Pierre Auger Observatory with zenith angles up to 80°

In this study, we present the results of an analysis of the large angular scale distribution of the arrival directions of cosmic rays with energy above 4 EeV detected at the Pierre Auger Observatory including for the first time events with zenith angle between 60° and 80°. We perform two Rayleigh analyses, one in the right ascension and one in the azimuth angle distributions, that are sensitive to modulations in right ascension and declination, respectively. The largest departure from isotropy appears in the $$E\gt 8$$ EeV energy bin, with an amplitude for the first harmonic in right ascension $$r_{1}^{\alpha }=(4.4\pm 1.0)\times {{10}^{-2}}$$, that has a chance probability $$P(\geqslant r_{1}^{\alpha })=6.4\times {{10}^{-5}}$$, reinforcing the hint previously reported with vertical events alone.
Authors:
 [1]
  1. Univ. Siegen, Siegen (Germany). et al.
Publication Date:
OSTI Identifier:
1234871
Report Number(s):
FERMILAB-PUB--14-488-AD-AE-CD-TD
Journal ID: ISSN 1538-4357; arXiv eprint number arXiv:1411.6953
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal
Additional Journal Information:
Journal Volume: 802; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
The Pierre Auger Collaboration
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS astroparticle physics; cosmic rays