Related papers: Acceleration of Ultra High Energy Cosmic Rays
The energetics of electromagnetic acceleration of ultra-high-energy cosmic rays (UHECRs) is constrained both by confinement of a particle within an acceleration site and by radiative energy losses of the particle in the confining magnetic…
Ultra High Energy Cosmic Rays, UHECR, are charged particles with energies between $\sim10^{18}\,{\rm eV}$ and $\sim3\times10^{20}\,{\rm eV}\sim50\,{\rm J}$. They exhibit fundamental physics at energies inaccessible to terrestrial…
Understanding the origins of ultrahigh energy cosmic rays (UHECRs) - which reach energies in excess of $10^{20}~{\rm eV}$ - stretches particle acceleration physics to its very limits. In this review, we discuss how such energies can be…
Ultra-High-Energy Cosmic Rays (UHECRs), particles characterized by energies exceeding $10^{18}$ eV, are generally believed to be accelerated electromagnetically in high-energy astrophysical sources. One promising mechanism of UHECR…
The origin of the ultra high energy cosmic rays (UHECR) with energies above E > 1017eV, is still unknown. The discovery of their sources will reveal the engines of the most energetic astrophysical accelerators in the universe. This is a…
The origin of the highest energy cosmic rays is still unknown. The discovery of their sources will reveal the workings of the most energetic astrophysical accelerators in the universe. Current observations show a spectrum consistent with an…
A mechanism of ultra-high energy (UHE) cosmic ray acceleration in extragalactic radio sources at the interface between the relativistic jet and the ambient medium is discussed as a supplement to the shock acceleration in `hot spots'.…
It is argued that there are three `origins' of cosmic rays; the origin of the particles, the origin of the energy, and the site of the acceleration. The evidence for each origin is discussed and a plausible synthesis outlined for the…
We shortly discuss several astrophysical scenarios leading to cosmic ray acceleration up to extremely high energies reaching the scale of 10^{20} eV. The processes suggested in the literature include acceleration at relativistic jet…
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…
Large-scale accretion shocks around massive clusters of galaxies, generically expected in the cold dark matter scenario of cosmological structure formation, are shown to be plausible sources of the observed ultrahigh energy cosmic rays…
We propose that nearly every accelerated CR was part of the parallel current that maintains all force-free (f-f) magnetic fields. Charged particles are accelerated by the E-parallel (to the magnetic filed B) produced by reconnection. The…
Significant progress has been made over the past decades towards unveiling the sources of the most energetic particles in nature, the ultra-high-energy cosmic rays (UHECRs). Despite these advancements, the exact astrophysical sites capable…
Cosmic ray particles with energies in excess of 10**(20) eV have been detected. The sources as well as the physical mechanism(s) responsible for endowing cosmic ray particles with such enormous energies are unknown. This report gives a…
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 current status of Ultra High Energy Cosmic Rays (UHECR) is reviewed, with emphasis given to theoretical interpretation of the observed events. The galactic and extragalactic origin, in case of astrophysical sources of UHE particles,…
We explore two generic hypotheses for tracing the sources of ultra-high energy cosmic rays (UHECRs) in the Universe: star formation rate density or stellar mass density. For each scenario, we infer a set of constraints for the emission…
Large-scale accretion shocks around massive clusters of galaxies, generically expected in hierarchical scenarios of cosmological structure formation, are shown to be potential sources of the observed ultrahigh energy cosmic rays (UHECRs) by…
The origin of cosmic rays with energies higher than 10$^{20}$ eV remains a mystery. Accelerating particles up to these energies is a challenge even for the most energetic astrophysical objects known. While the isotropy in arrival directions…
We review the physics of the highest energy cosmic rays. The discovery of their sources, still unknown, will reveal the most energetic astrophysical objects in the universe and could unveil new physics beyond the standard model of particle…