Evidence for declination dependence of ultrahigh energy cosmic ray spectrum in the northern hemisphere

R. U. Abbasi (Author), Mitsuhiro Abe (Author), T. Abu-Zayyad (Author), M. Allen (Author), R. Azuma (Author), E. Barcikowski (Author), J. W. Belz (Author), D. R. Bergman (Author), S. A. Blake (Author), J. P. Lundquist (Author)

Abstract

The energy of the ultrahigh energy spectral cutoff was measured, integrating over the northern hemisphere sky, by the Telescope Array (TA) collaboration, to be 10^19.78±0.06 eV, in agreement with the High Resolution Fly's Eye (HiRes) experiment, whereas the Pierre Auger experiment, integrating over the southern hemisphere sky, measured the cutoff to be at 10^19.62±0.02 eV. An 11% energy scale difference between the TA and Auger does not account for this difference. However, in comparing the spectra of the Telescope Array and Pierre Auger experiments in the band of declination common to both experiments ( −15.7∘<δ<24.8∘ ) we have found agreement in the energy of the spectral cutoff. While the Auger result is essentially unchanged, the TA cutoff energy has changed to 10^19.59±0.06 eV. In this paper we argue that this is an astrophysical effect.

Keywords

astrophysics;high energy astrophysical phenomena;UHECR;cosmic rays;anisotropy;

Data

Language:	English
Year of publishing:	2018
Typology:	1.25 - Other Component Parts
Organization:	UNG - University of Nova Gorica
UDC:	524
COBISS:	12839939
ISSN:	2331-8422
Views:	2250
Downloads:	78
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