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.
Highlights
Ultra-high-energy cosmic rays (UHECRs) are particles reaching the Earth from outer space with energies above 1018 eV
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
We present the result of a simple phenomenological model of UHECR sources to Pierre Auger Observatory measurements of the energy spectrum and Xmax distributions for energies above 1018.7 eV, as a demonstration of the constraining power of Auger data
Summary
Ultra-high-energy cosmic rays (UHECRs) are particles reaching the Earth from outer space with energies above 1018 eV. More than half a century after their discovery, their origin is still unknown, but there is a wide consensus that most of the highest-energy cosmic rays originate outside of our galaxy If this is the case, their energy spectrum and mass composition is non-trivially affected by interactions with photon backgrounds during their propagation through intergalactic space, making it harder to infer properties of their sources from Earth-based observations. The FD provides us with measurements of the shower maximum depth Xmax, the most important observable sensitive to the mass composition of UHECRs. We present the result of a simple phenomenological model of UHECR sources to Pierre Auger Observatory measurements of the energy spectrum and Xmax distributions for energies above 1018.7 eV, as a demonstration of the constraining power of Auger data. An updated version of this work will be published in ref. [6]
Sign-in/Register to view highlights & summary 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.
