Astrophysical interpretation of Pierre Auger Observatory measurements of the UHECR energy spectrum and mass composition

Abstract

We present a combined fit of a simple astrophysical model of UHECR sources to both the energy spectrum and mass composition data measured by the Pierre Auger Observatory. The fit has been performed for energies above 5 EeV, i.e. the region of the all-particle spectrum above the so-called "ankle" feature. The astrophysical model we adopted consists of identical sources uniformly distributed in a comoving volume, where nuclei are accelerated with a rigidity-dependent mechanism. The fit results suggest sources characterized by relatively low maximum injection energies and hard spectral indices. The impact of various systematic uncertainties on the above result is discussed.

4 pages, 1 figure, 1 table; published in the proceedings of the 6th Roma International Conference on Astroparticle Physics (RICAP16), 21-24 June 2016, Frascati (Rome), Italy

References in corpus (4)

• The Pierre Auger Cosmic Ray Observatory
• Depth of Maximum of Air-Shower Profiles at the Pierre Auger Observatory: Measurements at Energies above 10^17.8 eV
• Indications of Negative Evolution for the Sources of the Highest Energy Cosmic Rays
• Effects of uncertainties in simulations of extragalactic UHECR propagation, using CRPropa and SimProp