Cosmic-ray-induced filamentation instability in collisionless shocks

D. Caprioli, Anatoly Spitkovsky

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


We used unprecedentedly large two-dimensional and three-dimensional hybrid (kinetic ions - fluid electrons) simulations of non-relativistic collisionless strong shocks in order to investigate the effects of self-consistently accelerated ions on the overall shock dynamics. The current driven by suprathermal particles streaming ahead of the shock excites modes transverse to the background magnetic field. The Lorentz force induced by these self-amplified fields tends to excavate tubular, underdense, magnetic-field-depleted cavities that are advected with the fluid and perturb the shock surface, triggering downstream turbulent motions. These motions further amplify the magnetic field, up to factors of 50-100 in knot-like structures. Once downstream, the cavities tend to be filled by hot plasma plumes that compress and stretch the magnetic fields in elongated filaments; this effect is particularly evident if the shock propagates parallel to the background field. Highly magnetized knots and filaments may provide explanations for the rapid X-ray variability observed in RX J1713.7-3946 and for the regular pattern of X-ray bright stripes detected in Tycho's supernova remnant.

Original languageEnglish (US)
Article numberL20
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Mar 1 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • ISM: supernova remnants
  • acceleration of particles
  • magnetic fields
  • shock waves


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