Propagation of extragalactic ultra-high energy cosmic-ray nuclei : implications for the observed spectrum and composition

Understand

In this paper, we study the propagation of cosmic-ray nuclei and protons.

• We emphasize the influence of the source composition on the expected spectrum and composition on Earth as well as on the phenomenology of the transition from Galactic to extragalactic cosmic-rays and the interpretation of the ankle.
• We point out that the different source composition models cannot be distinguished on the sole basis of the cosmic-ray spectrum but that the the energy evolution of $<X_{\max}>$ should remove this degeneracy.
• Finally, we compare the predictions for the different source composition models with the available data and discuss the implications of our results.