T. Abu-Zayyad (Author), R. Aida (Author), M. Allen (Author), R. Anderson (Author), R. Azuma (Author), E. Barcikowski (Author), J. W. Belz (Author), D. R. Bergman (Author), S. A. Blake (Author)

Abstract

We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events collected by the Telescope Array (TA) detector in the first 40 months of operation. Following earlier studies, we examine event sets with energy thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the events in right ascension and declination are compatible with an isotropic distribution in all three sets. We then compare with previously reported clustering of the UHECR events at small angular scales. No significant clustering is found in the TA data. We then check the events with E > 57 EeV for correlations with nearby active galactic nuclei. No significant correlation is found. Finally, we examine all three sets for correlations with the large-scale structure (LSS) of the universe. We find that the two higher-energy sets are compatible with both an isotropic distribution and the hypothesis that UHECR sources follow the matter distribution of the universe (the LSS hypothesis), while the event set with E > 10 EeV is compatible with isotropy and is not compatible with the LSS hypothesis at 95% CL unless large deflection angles are also assumed. We show that accounting for UHECR deflections in a realistic model of the Galactic magnetic field can make this set compatible with the LSS hypothesis.

Keywords

acceleration of particles;astroparticle physics;cosmic rays;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UNG - University of Nova Gorica
UDC: 524
COBISS: 15998979 Link will open in a new window
ISSN: 0004-637X
Views: 2193
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Other data

URN: URN:SI:UNG
Type (COBISS): Not categorized
Pages: str. 1-11
Volume: ǂVol. ǂ757
Issue: ǂno. ǂ1
Chronology: 2012
DOI: 10.1088/0004-637X/757/1/26
ID: 11706013