Abstract
The energy spectra of ultra-high energy cosmic rays reported by the AGASA, Fly's Eye, Haverah Park, HiRes, and Yakutsk experiments are all shown to be in agreement with each other for energies below 1020 eV (after small adjustments, within the known uncertainties, of the absolute energy scales). The data from HiRes, Fly's Eye, and Yakutsk are consistent with the expected flux suppression above 5×1019 eV due to interactions of cosmic rays with the cosmic microwave background, the Greisen–Zatsepin–Kuzmin (GZK) suppression, and are inconsistent with a smooth extrapolation of the observed cosmic-ray energy spectrum to energies >5×1019 eV. AGASA data show an excess of events above 1020 eV, compared to the predicted GZK suppression and to the flux measured by the other experiments.
Highlights
We analyze the observed spectrum of ultra-high energy cosmic rays
We find two main results: (i) The energy spectra reported by the AGASA, Fly’s Eye, Haverah Park, HiRes and Yakutsk experiments are all in good agreement for energies below 1020 eV, and (ii) All the data are consistent with a GZK suppression except for the AGASA points above 1020 eV
Our principal conclusion from these two results is that standard physics, including the GZK suppression, is sufficient to explain all of the existing data on ultra-high energy (UHE) cosmic rays
Summary
We analyze the observed spectrum of ultra-high energy cosmic rays. Our principal conclusion from these two results is that standard physics, including the GZK suppression, is sufficient to explain all of the existing data on UHE cosmic rays. For any theoretical model in which the GZK suppression is present, the assumed intrinsic spectrum produced by the UHE cosmic-ray sources influences the energy spectrum predicted by the model. Are consistent with a GZK suppression implies that the observed spectrum is consistent with model predictions for a plausible intrinsic energy spectrum. We show that the observed spectrum is consistent with that expected for a GZK suppression of the flux produced by a simple cosmological distribution of sources, each source producing high energy protons with a spectrum dN/dEp ∝ Ep−2 characteristic for collisionless shock acceleration. Before entering into any details, we will summarize and compare in this introduction the data that are available from different collaborations that measure the spectrum of ultra high energy cosmic rays
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
