Abstract
The Galactic cosmic ray (CR) fluxes observed in the vicinity of the Earth encode the space and time averaged properties of their sources and are also shaped by the effects of their propagation in the Galaxy. A combined study of the spectra of different particle types (protons, primary and secondary nuclei, electrons, positrons and antiprotons) is essential to determine the roles of the source and of propagation in the formation of the fluxes. Several authors are now claiming that these combined studies have essentially solved the problem, and that the properties of CR propagation, and the source spectra for all particle types are now well determined in a broad energy range, with significant uncertainties only at high energy. In this contribution we analyse critically these results, and conclude that the problem of determining in good approximation the average CR source spectra (and therefore also the main properties of CR propagation) remains open, with very large uncertainties. Solving this problem has profound implications for the properties of the Galactic CR accelerators (that have not yet been firmly identified) and for our understanding of the Milky Way magnetic structure. Future observations, especially of electrons and positrons in the multi-TeV range and of unstable isotopes like beryllium in the few GeV range should soon allow to solve the problem.
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