A complete model of the CR spectrum and composition across the Galactic to Extragalactic transition

TL;DR

This paper develops a comprehensive model of cosmic-ray spectrum and composition across the Galactic to extragalactic transition, fitting current data with minimal assumptions and no additional components.

Contribution

It introduces a unified phenomenological model based on a single Galactic component and an extragalactic component, aligning with observational constraints without extra assumptions.

Findings

The model fits data from KASCADE Grande and Auger.

It shows the Galactic/extragalactic transition can be explained with two main components.

The model predicts generic features consistent with cosmic-ray observations.

Abstract

We present a complete phenomenological model accounting for the evolution of the cosmic-ray spectrum and composition with energy, based on the available data over the entire spectrum. We show that there is no need to postulate any additional component, other than one single Galactic component depending on rigidity alone, and one extragalactic component, whose characteristics are similar to those derived from a study of particle acceleration at mildly relativistic shocks in a GRB environment (Globus et al., 2015). In particular, we show that the resulting cosmic ray spectrum and composition satisfy the various constraints derived from the current data in the Galactic/extragalactic transition region, notably from the measurements of KASCADE Grande and Auger. Finally, we derive some generic features that a working phenomenological scenario may exhibit to give a global account of the cosmic ray data with a minimum number of free parameters.