Extragalactic ultra-high energy cosmic rays. II. Comparison with experimental data
Abstract
The hot spots of powerful Fanaroff Riley class II radio galaxies and related radio quasars can produce an ultra-high energy particle population observable at earth. The properties of the predicted spectrum are a spectrum which is about E^-2^ below 0.1 EeValpha^, steepening to about E^-2.75^ near 1 EeV, and cutting off due to interaction with the cosmic microwave background after a bump just below 100 EeV (Rachen & Biermann 1992, paper UHE-CR I); the predicted chemical composition is a strong dominance of protons. Here we compare this prediction with observational data from both the Fly's Eye and the Akeno airshower detectors. These experimental data are now available from the detailed analysis of the chemical composition near to EeV energies (Gaisser et al. 1992 for the Fly's Eye experiment, and from Stanev et al. 1992 for the Akeno experiment) and demonstrate that below 1 EeV protons show a flatter spectrum than the overall spectrum and thus their relative proportion increases with energy. The comparison of the spectral data and the flux shows that the ultra high energy component of the cosmic rays can indeed be understood as arising from the hot spots of powerful radiogalaxies, in flux, spectrum and chemical composition: This result put stringent limits on the propagation of high energy cosmic rays and thus on the properties of the intergalactic magnetic field.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- June 1993
- DOI:
- 10.48550/arXiv.astro-ph/9302005
- arXiv:
- arXiv:astro-ph/9302005
- Bibcode:
- 1993A&A...273..377R
- Keywords:
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- Astrophysics
- E-Print:
- 9 pages, LaTeX, 3 figures (available upon request), MPIfR Preprint Series No.514 Accepted by Astronomy &