1. Large-scale cosmic-ray anisotropies with 19 yr of data from the Pierre Auger ObservatoryA. Abdul Halim, P. Abreu, M. Aglietta, Ingo Allekotte, K. Almeida Cheminant, Jon Paul Lundquist, Shima Ujjani Shivashankara, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2024, original scientific article Abstract: We present results of the measurement of large-scale anisotropies in the arrival directions of
ultra–high-energy cosmic rays detected at the Pierre Auger Observatory during 19 yr of operation,
prior to AugerPrime, the upgrade of the observatory. The 3D dipole amplitude and direction are
reconstructed above 4 EeV in four energy bins. Besides the established dipolar anisotropy in right
ascension above 8 EeV, the Fourier amplitude of the 8–16 EeV energy bin is now also above the 5σ
discovery level. No time variation of the dipole moment above 8 EeV is found, setting an upper limit
to the rate of change of such variations of 0.3% per year at the 95% confidence level. Additionally,
the results for the angular power spectrum are shown, demonstrating no other statistically
significant multipoles. The results for the equatorial dipole component down to 0.03 EeV are
presented, using for the first time a data set obtained with a trigger that has been optimized for
lower energies. Finally, model predictions are discussed and compared with observations, based
on two source emission scenarios obtained in the combined fit of spectrum and composition above 0.6 EeV.
Keywords: ultra–high-energy cosmic rays, UHECRs, UHECR anisotropies, Pierre Auger Observatory, dipolar anisotropy in right ascension, Fourier amplitude analysis, angular power spectrum, equatorial dipole component, UHECR source emission scenarios
Published in RUNG: 26.11.2024; Views: 436; Downloads: 1
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