相关论文: Cosmic Rays X. The cosmic ray knee and beyond: Dif…
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…
We present the model of cosmic rays acceleration at ultrarelativistic subshocks and confront it with the observations of gamma-ray bursts and blazars. We investigate cosmic rays acceleration in shocks with Lorentz factors in the range 3 -…
Supernova remnants (SNRs) are believed to accelerate particles up to high energies through the mechanism of diffusive shock acceleration (DSA). Except for direct plasma simulations, all modeling efforts must rely on a given form of the…
Cosmic-ray scattering on magnetic turbulence leads to spatial diffusive propagation; if the scattering medium is moving, this will inevitably also cause changes in the momentum of the particles, so-called diffusive reacceleration. This can…
We obtain the angular distribution of the cosmic rays reaching an observer from an individual source and after propagation through a turbulent magnetic field, for different ratios between the source distance and the diffusion length. We…
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…
The problem of the origin of cosmic rays in the shocks produced by supernova explosions at energies below the so called 'knee' (at ~3*10$^6$ GeV) in the energy spectrum is addressed, with special attention to the propagation of the…
Cosmic ray propagation is diffusive because of pitch angle scattering by waves. We demonstrate that if the high-amplitude magnetohydrodynamic turbulence with $\tilde B/\langle B\rangle \sim 1$ is present on top of the mean field gradient,…
We derive the maximum accelerated particle energy from first-order and second-order Fermi acceleration at nonrelativistic and relativistic shocks for explosions taking place in a uniform surrounding medium. Second-order stochastic processes…
One of the most striking astrophysical phenomena today is the existence of cosmic ray particles with energies in excess of 10^20 eV. While their presence has been confirmed by a number of experiments, it is not clear where and how these…
Recent progress in cosmic ray physics covering the energy range from about 10^{14} eV to 10^{19} eV is reviewed. The most prominent features of the energy spectrum are the so called `knee' at E ~ 3 * 10^{15} eV and the `ankle' at few…
A leading explanation for the origin of Galactic cosmic rays is acceleration at high-Mach number shock waves in the collisionless plasma surrounding young supernova remnants. Evidence for this is provided by multi-wavelength non-thermal…
Theory of the first-order Fermi acceleration of cosmic ray particles at relativistic shock waves is reviewed. We consider shocks with parallel and oblique, sub- and super-luminal magnetic field configurations and with finite-amplitude…
This work establishes oblique shocks in Massive Star Clusters (MSC) as a primary mechanism for accelerating cosmic rays (CR) up to the knee of the energy spectrum. We develop a model that incorporates the combined contribution of supernova…
The role of cosmic rays generated by supernovae and young stars has very recently begun to receive significant attention in studies of galaxy formation and evolution due to the realization that cosmic rays can efficiently accelerate…
We show that the energy required to turbulently amplify magnetic field during cosmic ray (CR) acceleration by shocks extracts energy from the CR and steepens the CR energy spectrum.
A mechanism of ultra-high energy cosmic ray acceleration in extragalactic radio sources, at the interface between the relativistic jet and the surrounding medium, is discussed as a supplement to the shock acceleration in `hot spots'. Due to…
Cosmic rays represent one of the most important energy transformation processes of the universe. They bring information about the surrounding universe, our galaxy, and very probably also the extragalactic space, at least at the highest…
Cosmic rays are the most energetic particles arriving at earth. Although most of them are thought to be accelerated by supernova remnants, the details of the acceleration process and its efficiency are not well determined. Here we show that…
Although cosmic rays were discovered over 100 years ago their origin remains uncertain. They have an energy spectrum that extends from 1 GeV to beyond 1020 eV, where the rate is less than 1 particle per km2 per century. Shortly after the…