Impact of the EPOS.LHC-R hadronic interaction model on the Centaurus A ultrahigh-energy cosmic-ray scenario

TL;DR

This paper evaluates how the EPOS.LHC-R hadronic interaction model influences the interpretation of ultrahigh-energy cosmic rays from Centaurus A, affecting composition estimates, spectral features, and anisotropy predictions.

Contribution

It introduces a new approach to determine cosmic ray masses from air shower data and assesses the impact of the EPOS.LHC-R model on cosmic ray origin scenarios.

Findings

Heavier composition inferred with EPOS.LHC-R reduces hydrogen and helium emission.

CNO elements dominate just above the ankle energy region.

Predicted dipolar anisotropy aligns with observations under certain magnetic field conditions.

Abstract

We discuss the impact of the recent EPOS.LHC-R hadronic interaction model on the scenario in which most of the cosmic rays with energies above 5 EeV originate in the nearby Centaurus A radiogalaxy. The heavier composition inferred when considering this hadronic model implies that the amount of H and He emitted by the source is reduced compared to what was found with previous hadronic models. The elements of the CNO group play a more predominant role in the instep region just above the ankle while the elements of the Si and Fe groups can contribute significantly in the suppression region of the energy spectrum above 50 EeV. We also obtain the predictions for the amplitude of the dipolar anisotropy in different energy bins above 4 EeV, showing that they can be well consistent with the measurements for appropriate values of the extragalactic turbulent magnetic field and source lifetime. A new method to extract the information on the cosmic ray masses from that of the depth of the maximum development of the air showers is also introduced.