Related papers: High-Energy Cosmic Rays from Radio Galaxies
In this work we present the interpretation of the energy spectrum and mass composition data as measured by the Pierre Auger Collaboration above $6 \times 10^{17}$ eV. We use an astrophysical model with two extragalactic source populations…
The apparent lack of suitable astrophysical sources for cosmic rays with E > 10^{19.7} eV (UHECRs) is the "GZK Paradox". We argue that whatever mechanism produces them must also account for events down to ~10^{18.7} eV, including their…
A model is proposed for the origin of cosmic rays (CRs) from ~10^14 eV to the highest energies, >10^20 eV. Gamma-Ray Bursts (GRBs) are assumed to inject CR protons and ions into the interstellar medium of star-forming galaxies--including…
We constrain the energy at which the transition from Galactic to extragalactic cosmic rays occurs by computing the anisotropy at Earth of cosmic rays emitted by Galactic sources. Since the diffusion approximation starts to loose its…
A model for high-energy (>10^14 eV) cosmic rays (HECRs) from galactic and extragalactic gamma-ray bursts (GRBs) is summarized. Relativistic outflows in GRBs are assumed to inject power-law distributions of CR protons and ions to the highest…
Some new developments obtained in the last few years concerning the propagation of high energy cosmic rays are discussed. In particular, it is shown how the inclusion of drift effects in the transport diffusion equations leads naturally to…
We consider the stochastic propagation of high-energy protons and nuclei in the cosmological microwave and infrared backgrounds, using revised photonuclear cross-sections and following primary and secondary nuclei in the full 2D nuclear…
A very recent observation by the Auger Observatory group claims strong evidence for cosmic rays above 56 EeV being protons from Active Galactic Nuclei. If, as would be expected, the particles above the ankle at about 2 EeV are almost all of…
We have argued [J. Szabelski et al. (2002)] that the well-known `ankle' in the cosmic ray energy spectrum, at logE (eV) ~ 18.7-19.0, marks the transition from mainly Galactic sources at lower energies to mainly extragalactic above.…
The origin of Galactic cosmic rays (with energies up to 10^15 eV) remains unclear, though it is widely believed that they originate in the shock waves of expanding supernova remnants. Currently the best way to investigate their acceleration…
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 most recent experimental results on the cosmic ray composition and energy spectrum above 1 TeV are reviewed and discussed. All data agree on the presence of the so-called ``knee'' at an energy E(knee) = 3-4 PeV; the knee is seen in all…
Arrival directions of ultra-high energy cosmic rays from the direction of ten brightest radio sources lying within 50 Mpc from our Galaxy were studied by using recent models of the largescale Galactic magnetic field. A detailed study, where…
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…
Recent accurate measurements of cosmic-ray (CR) protons and nuclei by ATIC-2, CREAM, and PAMELA reveal: a) unexpected spectral hardening in the spectra of CR species above a few hundred GeV per nucleon, b) a harder spectrum of He compared…
The propagation of ultra high energy cosmic rays in Galactic and extragalactic magnetic fields is investigated in the present paper. The motion of charged particles of different energies and chemical composition is simulated using different…
The energy spectrum, composition and arrival directions of ultrahigh energy cosmic rays (UHECRs) with energy above the cosmic ray ankle, measured by the Pierre Auger Observatory, are inconsistent if their origin is assumed to be…
The origin of the ultra high energy cosmic rays (UHECRs, $E>10^{18}$ eV) is still uncertain. However, great progress has been achieved due to the data taken by The Pierre Auger and Telescope Array observatories. The UHECR flux presents two…
The origin of cosmic rays is one of the major unresolved questions in astrophysics. In particular, the highest energy cosmic rays observed possess macroscopic energies and their origin is likely associated with the most energetic processes…
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…