Abstract
The possibility for a self-consistent description of all the basic features of the observed cosmic ray spectra and primary composition variations in the energy range of $10^{15}\div 10^{20}$ eV within the Galactic origin scenario is examined. We assume the existence of Galactic sources that accelerate particles up to $\sim 3\cdot 10^{18}Z$ eV and take into account a highly inhomogeneous (fractal-like) distribution of matter and magnetic fields in the Galaxy that leads to extremely large free paths of particles ("L\'{e}vy flights"), along with an overwhelming contribution to the cosmic ray fluxes observed above $\sim 10^{18}$ eV from particles reaching the Solar System without scattering. Our scenario was refined on the basis of recent experimental results on primary mass composition. Model predictions, which could be verified with the improved high-precision measurements in the nearest future are discussed.
Highlights
Physical mechanisms governing the features of energy spectra of cosmic rays (CRs) and their composition variations in the energy range that spans from PeV to tens of EeV are still under debate
In the framework of the model described above we have analysed the energy spectra and mass composition behaviour in the energy range up to the cut-off observed at ∼ 5 · 1019 eV
If anomalous diffusion is, the main mechanism of the knee feature, the injection spectra exponent could be estimated from the analysis of the experimentally measured energy spectra around the knee
Summary
Physical mechanisms governing the features of energy spectra of cosmic rays (CRs) and their composition variations in the energy range that spans from PeV to tens of EeV are still under debate. The so-called standard scenario assumes that the Galactic component of CRs accelerated by supernova remnants extends up to energies of a few 1017 eV with gradually heavier composition due to the rigidity-dependent maximum acceleration energy of nuclei. The non-GZK origin of the energy spectrum suppression at the highest energies (e.g., the acceleration limits in Galactic cosmic ray sources above 1018 eV) can not be excluded. In the present paper we revise the possibility of the self-consistent description of the CRs energy spectra and composition results within the Galactic cosmic ray origin scenario based on the anomalous diffusion model and discuss the crucial model predictions, which could be verified with improved high-precision measurements in the near future
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