Selected Topics in Cosmic Ray Physics

TL;DR

This paper reviews recent observational and theoretical advances in cosmic ray physics, focusing on their origins, the galactic-extragalactic transition, and the implications for cosmic ray source models.

Contribution

It provides a comprehensive summary of recent developments in cosmic ray observations and models, especially regarding the transition region between galactic and extragalactic sources.

Findings

Support for the supernova paradigm for galactic cosmic rays

Insights into the cosmic ray spectrum and composition at high energies

Discussion on the transition energy between galactic and extragalactic cosmic rays

Abstract

The search for the origin of cosmic rays is as active as ever, mainly driven by new insights provided by recent pieces of observation. Much effort is being channelled in putting the so called supernova paradigm for the origin of galactic cosmic rays on firmer grounds, while at the highest energies we are trying to understand the observed cosmic ray spectra and mass composition and relating them to potential sources of extragalactic cosmic rays. Interestingly, a topic that has acquired a dignity of its own is the investigation of the transition region between the galactic and extragalactic components, once associated with the ankle and now increasingly thought to be taking place at somewhat lower energies. Here we summarize recent developments in the observation and understanding of galactic and extragalactic cosmic rays and we discuss the implications of such findings for the modelling of the transition between the two.