Esteban Roulet (Author), Andrej Filipčič (Author), J. P. Lundquist (Author), S. U. Shivashankara (Author), Samo Stanič (Author), Serguei Vorobiov (Author), Danilo Zavrtanik (Author), Marko Zavrtanik (Author)

Abstract

An update of the measurements of large-scale anisotropies in the arrival directions of ultra high-energy cosmic rays detected at the Pierre Auger Observatory is presented. The established dipolar anisotropy in right ascension has now reached a significance of 6.8σ when considering all energies above 8 EeV and 5.7 σ when only considering energies between 8 and 16 EeV. The 3D dipole amplitude and direction are reconstructed in four different energy bins above 4 EeV. At energies above 8 EeV it points more than 100∘ away from the Galactic centre, providing evidence that the anisotropy observed is of extragalactic origin. An analysis allowing for both dipolar and quadrupolar anisotropies finds qualitatively similar dipole components and no significant quadrupole components. The results for the angular power spectrum are shown, demonstrating that no other statistically significant multipoles are present. The equatorial dipole components are presented down to 0.03 EeV using a trigger which has been optimized for low energies. We find no significant departures from isotropic expectations below 8 EeV, although below 2 EeV the phases appear to be consistently aligned with the right ascension of the Galactic centre. Finally, model predictions based on source emission scenarios obtained in the combined fit of spectrum and composition data above 0.6 EeV are discussed and compared with observations.

Keywords

ultra-high-energy cosmic rays;Pierre Auger Observatory;large scale anisotropies;

Data

Language: English
Year of publishing:
Typology: 1.08 - Published Scientific Conference Contribution
Organization: UNG - University of Nova Gorica
UDC: 52
COBISS: 230056195 Link will open in a new window
ISSN: 1824-8039
Views: 370
Downloads: 9
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Other data

Pages: 7 str.
DOI: 10.22323/1.484.0008
ID: 26106970