Collisionless shocks and turbulence in nonthermal sources of radiation

• Applicant: Professor Dr. Martin Karl Wilhelm Pohl
• Subject Area: Astrophysics and Astronomy
• Term: from 2010 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 173137393

We explore the properties of magnetic turbulence near the forward shocks of shell-type supernova remnants (SNR) and their role the acceleration of energetic particles. A thorough understanding of the relations between turbulence and energetic particles would have profound consequences for a number of important scientific questions, among them the origin of cosmic rays, the generation of primordial magnetic fields, and the properties of driven turbulence in a system far from equilibrium. We perform kinetic Particle-in-Cell (PIC) simulations, because plasma turbulence at collisionless shocks has very small wavelength scales and cannot be realistically described with MHD methods. Our parallel code is highly scalable and thus permits computer experiments over an appropriately wide range of physical scales.Our research is driven by the following basic questions: What are the characteristics of strong magnetic turbulence near a collisionless shock with efficient particle acceleration? Also, what are the properties of collisionless shocks in a strongly turbulent medium? While longterm-evolution studies have been performed for relativistically colliding plasma shells and the associated shocks, it is of utmost importance to study the systems for which we have much more direct observations, and for which we know the geometry: the nonrelativistic shocks of SNRs.

• DFG Programme: Research Grants