On the efficiency of Fermi acceleration at relativistic shocks
arXiv:astro-ph/0606005 · doi:10.1086/506322
Abstract
It is shown that Fermi acceleration at an ultra-relativistic shock wave cannot operate on a particle for more than 1 1/2 Fermi cycle (i.e., u -> d -> u -> d) if the particle Larmor radius is much smaller than the coherence length of the magnetic field on both sides of the shock, as is usually assumed. This conclusion is shown to be in excellent agreement with recent numerical simulations. We thus argue that efficient Fermi acceleration at ultra-relativistic shock waves requires significant non-linear processing of the far upstream magnetic field with strong amplification of the small scale magnetic power. The streaming or transverse Weibel instabilities are likely to play a key role in this respect.
4 pages, 2 figures; to appear in ApJ Letters
Cited by in corpus (22)
- On the Momentum Diffusion of Radiating Ultrarelativistic Electrons in a Turbulent Magnetic Field
- Pulsar Wind Nebulae as Cosmic Pevatrons: A Current Sheet's Tale
- On Fermi acceleration and MHD-instabilities at ultra-relativistic magnetized shock waves
- High-energy cosmic ray nuclei from tidal disruption events: Origin, survival, and implications
- PIC Simulation Methods for Cosmic Radiation and Plasma Instabilities
- Synchrotron emission in the fast cooling regime: which spectra can be explained?
- Particle Transport in intense small scale magnetic turbulence with a mean field
- Non-linear collisionless damping of Weibel turbulence in relativistic blast waves
- Acceleration and propagation of ultra high energy cosmic rays
- Describing the Observed Cosmic Neutrinos by Interactions of Nuclei with Matter
- A corrugated termination shock in pulsar wind nebulae?
- Shock Vorticity Generation from Accelerated Ion Streaming in the Precursor of Ultrarelativistic Gamma-Ray Burst External Shocks
- Nucleonic gamma-ray production in Pulsar Wind Nebulae
- A fast current-driven instability in relativistic collisionless shocks
- Ultra High Energy Cosmic Ray Source Models: Successes, Challenges and General Predictions
- Fast Particle Acceleration at Perpendicular Shocks with Uniform Upstream Magnetic Field and Strong Downstream Turbulence
- Saturation of the asymmetric current filamentation instability under conditions relevant to relativistic shock precursors
- Acceleration of ultra-high energy cosmic rays in the early afterglows of gamma-ray bursts: concurrence of jet's dynamics and wave-particle interactions
- INTEGRAL observations of TeV plerions
- Particle acceleration and magnetic field amplification by relativistic shocks in inhomogeneous media
- Acceleration of cosmic rays in presence of magnetohydrodynamic fluctuations at small scales
- Macroscopic magnetization of primordial plasma by virial shocks