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
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.,
Aloisio, R.,
Alvarez-Muñiz, J.,
Ambrosone, A.,
Ammerman Yebra, J.,
Anastasi, G.,
Anchordoqui, L.,
Andrada, B.,
Andrade Dourado, L.,
Andringa, S.,
Apollonio, L.,
Aramo, C.,
Arnone, E.,
Arteaga Velázquez, J.,
Assis, P.,
Avila, G.,
Avocone, E.,
Bakalova, A.,
Barbato, F.,
Bartz Mocellin, A.,
Bellido, J.,
Berat, C.,
Bertaina, M.,
Bianciotto, M.,
Biermann, P.,
&
Binet, V.
(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