相关论文: Which acceleration process for UHE-Cosmic Rays in …
The origin, propagation, and mechanisms of acceleration of the ultra-high energy cosmic rays (UHECRs) are not yet well understood. Aiming for a better interpretation of the available experimental data, these data have to be confronted with…
We propose a model in which ultra high energy cosmic rays and gamma ray bursts are produced by collisions between neutron stars and axion stars. The acceleration of such a cosmic ray is made by the electric field, $\sim 10^{15} (B/10^{12}…
The study of ultra-high energy cosmic rays (UHECR) at Earth cannot prescind from the study of their propagation in the Universe. In this paper, we present HERMES, the \emph{ad hoc} Monte Carlo code we have developed for the realistic…
Gamma-Ray Bursts (GRBs) are expected to efficiently accelerate protons up to relativistic energies. High-energy photons can originate from decay of neutral pions produced by the interaction of these protons with the medium surrounding the…
A complete model for the origin of high-energy >~10^{14} eV) cosmic rays from gamma-ray bursts (GRBs) and implications of this hypothesis are described. Detection of high-energy neutrinos from GRBs provide an unambiguous test of the model.…
Gamma-ray bursts are generally considered to be the result of internal shocks generated in an inhomogeneous relativistic outflow that arises from a fireball. In such shocks, the Fermi acceleration of protons is naturally expected to be at…
A mechanism for proton acceleration to ~10^21eV is suggested. It may operate in accretion flows onto thin dark matter filaments of cosmic structure formation. The flow compresses the ambient magnetic field to strongly increase and align it…
GRBs are nowadays a rather well understood phenomenon in the soft (KeV-MeV) $\gamma$-ray energy band, while only a few GRBs have been observed at high photon energies ($E_{\gamma} \ut > 1$ GeV). It is also widely recognized that GRBs…
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…
Highly variable gamma-ray pulses and X-ray flares in GRB light curves can result from external shocks rather than central engine activity under the assumption that the GRB blast-wave shell does not spread. Acceleration of cosmic rays to…
The origin of the highest energy cosmic rays remains an enigma. They offer a window to new physics, including tests of physical laws relevant to their propagation and interactions, at energies unattainable by terrestrial accelerators. They…
Gamma-ray bursts (GRBs) have long been suspected as possible ultra-high energy cosmic ray (UHECR) accelerators. In this brief note, I report that GRB 980425/SN 1998bw falls within the region of interest (ROI) with the highest significance…
Gamma-Ray Bursts (GRBs) are the must violent explosions after the Big-Bang. Their high energy radiation can potentially carry information about the most inner part of the accretion disk of a collapsing star, ionize the surrounding material…
The origin of ultra-high energy cosmic rays (UHECRs) is one of the most mystifying issues in astroparticle physics. It has been suggested that gamma-ray bursts (GRBs) are excellent acceleration sites for cosmic rays. The propagation of…
It is proposed that the baryons in gamma ray burst (GRB) fireballs originate as "pick-up" neutrons that leak in sideways from surrounding baryonic matter and convert to protons in a collision avalanche. The asymptotic Lorentz factor is…
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…
In the cosmological blast-wave model for gamma ray bursts (GRBs), high energy (> 10 GeV) gamma-rays are produced either through Compton scattering of soft photons by ultrarelativistic electrons, or as a consequence of the acceleration of…
Collisionless entrainment of the surrounding matter imports the relativistic baryon component in the Gamma-Ray Burst (GRB) fireball frame. We show that half the fireball energy can be transferred from radiation to the comoving hot motions…
High energy neutrino emission from GRBs is discussed. In this paper, by using the simulation kit GEANT4, we calculate proton cooling efficiency including pion-multiplicity and proton-inelasticity in photomeson production. First, we estimate…
We give a brief review of the origin and acceleration of cosmic rays (CRs), emphasizing the production of CRs at different stages of supernova evolution by the first-order Fermi shock acceleration mechanism. We suggest that supernovae with…