Physics of relativistic shocks

2 00 8 On the origin of ultra high energy cosmic rays : Subluminal and superluminal relativistic shocks

The flux of ultra high energy cosmic rays (UHECRs) at E > 1018.5 eV is believed to arise in plasma shock environments in extragalactic sources. In this paper, we present a systematic study of particle acceleration by relativistic shocks, in particular concerning the dependence on bulk Lorentz factor and the angle between the magnetic field and the shock flow. For the first time, simulation resu...

Topical Issues for Particle Acceleration Mechanisms in Astrophysical Shocks

Particle acceleration at plasma shocks appears to be ubiquitous in the universe, spanning systems in the heliosphere, supernova remnants, and relativistic jets in distant active galaxies and gamma-ray bursts. This review addresses some of the key issues for shock acceleration theory that require resolution in order to propel our understanding of particle energization in astrophysical environmen...

Cosmic ray acceleration in subluminal and superluminal relativistic shock environments

The flux of Ultra High Energy Cosmic Rays (UHECRs) at E > 1018.5 eV is believed to arise in plasma shock environments in extragalactic sources. Galactic sources are not able to generate these high energies and the distribution of charged particles is too isotropic to originate from the galaxy. The best candidates for particle acceleration up to 1021 eV are believed to be the Active Galactic Nuc...

Fundamentals of Non-relativistic Collisionless Shock Physics: IV. Quasi-Parallel Supercritical Shocks

Radiative cooling in relativistic collisionless shocks. Can simulations and experiments probe relevant GRB physics?

We address the question of whether numerical particle-in-cell (PIC) simulations and laboratory laser-plasma experiments can (or will be able to, in the near future) model realistic gamma-ray burst (GRB) shocks. For this, we compare the radiative cooling time, tcool, of relativistic electrons in the shock magnetic fields to the microscopic dynamical time of collisionless relativistic shocks — th...