Related papers: High-energy Cosmic Rays
The propagation of high-energy cosmic rays in the Galaxy is investigated. Solutions of a diffusion model are combined with numerically calculated trajectories of particles. The resulting escape path length and interaction path length are…
We review the basic ideas on the origin of cosmic rays with energy in excess of $\sim 10^{19}$ eV, in the light of the most recent observational findings. The limited statistics of events detected by the two largest experiments currently…
Using the concept developed in earlier papers, that the cosmic rays originate in three different main sites, a) the normal supernova explosions into the interstellar medium, b) the supernova explosions into a stellar wind, and c) powerful…
Cosmic rays are charged relativistic particles that reach the Earth with extremely high energies, providing striking evidence of the existence of effective accelerators in the Universe. Below an energy around $\sim 10^{17}$ eV cosmic rays…
The origin of the knee in the energy spectrum of cosmic rays is an outstanding problem in astroparticle physics. Numerous mechanisms have been proposed to explain the structure in the all-particle spectrum. In the article basic ideas of…
The maximum cosmic ray energy achievable by acceleration by a relativistic blast wave is derived. It is shown that forward shocks from long GRB in the interstellar medium are powerful enough to produce the Galactic cosmic-ray component up…
It is proposed that the highest energy $\sim 10^{20}$eV cosmic ray primaries are protons, decay products of a long-lived progenitor whose high kinetic energy arises from decay of a distant (cosmological) superheavy particle, G. Such a…
The analysis of cosmic rays fluxes as a function of energy reveals a {\it knee} slightly below $10^{16}$ eV and an {\it ankle} close to $10^{19}$ eV. Their physical origins remain up to now quite enigmatic; in particular, no elementary…
The origin of cosmic rays is one of the major unresolved astrophysical questions. In particular, the highest energy cosmic rays observed possess macroscopic energies and their origin is likely to be associated with the most energetic…
Laboratory experiments to explore plasma conditions and stimulated particle acceleration can illuminate aspects of the cosmic particle acceleration process. Here we discuss the cosmic-ray candidate source object variety, and what has been…
The undisputed galactic origin of cosmic rays at energies below the so-called knee implies an existence of a nonthemal population of galactic objects which effectively accelerate protons and nuclei to TeV-PeV energies. The distinct…
The origin of the highest energy Galactic cosmic rays is still not understood, nor is the transition to EeV extragalactic particles. Scientific progress requires enhancements of existing air-shower arrays, such as: IceCube with its surface…
The origin of the highest-energy cosmic rays remains a mystery. The lack of a high energy cutoff in the cosmic ray spectrum together with an apparently isotropic distribution of arrival directions have strongly constrained most models…
Understanding the transition from Galactic to extragalactic cosmic rays (CRs) is essential to make sense of the Local cosmic ray spectrum. Several models have been proposed to account for this transition in the 0.1 - 10 $\times 10^{18}$ eV…
The present situation with regard to experimental data on ultra high-energy cosmic rays is briefly reviewed. Whilst detailed knowledge of the shape of the energy spectrum is still lacking, it is clear that events above 10^20 eV do exist.…
Recent international efforts have brought us closer to unveiling the century old mystery of the origin of cosmic rays. Cosmic ray, gamma ray, and neutrino observatories are reaching the necessary sensitivity to study the highest energy…
A brief review is given on the astrophysics of cosmic rays in the PeV primary energy range, i.e. the region of the knee.
The existence of the spectral break around $\sim 3 \times 10^{15}$ eV in the cosmic ray spectrum (referred to as the `knee') is one of the biggest questions in cosmic ray astrophysics. At the same time, the origin of cosmic rays above the…
We discuss the most recent developments in our understanding of the acceleration and propagation of cosmic rays up to the highest energies. In particular we specialize our discussion to three issues: 1) developments in the theory of…
The Very High Energy Gamma Ray Astronomy (VHE) is a rapidly evolving branch of modern astronomy, which covers the range from about 50 GeV to several tens of TeV from the ground. In the past years, the second generation instruments firmly…