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

Abstract

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:

Aab, Alexander ^[1]

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+ Show Author Affiliations

1. Univ. Siegen, Siegen (Germany). et al.

Publication Date:

Mon Mar 30 00:00:00 EDT 2015

Research Org.:

Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP)

Contributing Org.:

The Pierre Auger Collaboration

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

Resource Type:

Accepted Manuscript

Journal Name:

The Astrophysical Journal (Online)

Additional Journal Information:

Journal Name: The Astrophysical Journal (Online); Journal Volume: 802; Journal Issue: 2; Journal ID: ISSN 1538-4357

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; astroparticle physics; cosmic rays