Energy Spectrum of Ultrahigh-Energy Cosmic Rays across Declinations -90° to +44.8° as Measured at the Pierre Auger Observatory
Document Type
Article
Publication Date
12-12-2025
Department
Department of Physics
Abstract
The energy spectrum of cosmic rays above 2.5 EeV has been measured across the declination range -90°≤δ≤+44.8° using ∼310 000 events accrued at the Pierre Auger Observatory from an exposure of (104 900±3 100) km2 sr yr. No significant variations of energy spectra with declination are observed, after allowing or not for nonuniformities across the sky arising from the well-established dipolar anisotropies in the arrival directions of ultrahigh-energy cosmic rays. The instep feature in the spectrum at ≃10 EeV reported previously is now established at a significance above 5σ. Within the statistics, the energy spectra are indistinguishable across declinations so disfavoring an origin for the instep from a few distinctive sources.
Publication Title
Physical Review Letters
Recommended Citation
Abdul Halim, A.,
Abreu, P.,
Aglietta, M.,
Allekotte, I.,
Almeida Cheminant, K.,
Almela, A.,
Fick, B.,
Nguyen, K.,
Nitz, D.,
&
et al.
(2025).
Energy Spectrum of Ultrahigh-Energy Cosmic Rays across Declinations -90° to +44.8° as Measured at the Pierre Auger Observatory.
Physical Review Letters,
135(24).
http://doi.org/10.1103/p4l5-hxlf
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p2/2206