Magnetic Field Amplification by the Weibel Instability at Planetary and Astrophysical Shocks with High Mach Number
Artem Bohdan, M. Pohl, J. Niemiec, Paul Morris, Yosuke Matsumoto, Takanobu Amano, M. Hoshino, A. H. Sulaiman
Abstract
Collisionless shocks are ubiquitous in the Universe and often associated with a strong magnetic field. Here, we use large-scale particle-in-cell simulations of nonrelativistic perpendicular shocks in the high-Mach-number regime to study the amplification of the magnetic field within shocks. The magnetic field is amplified at the shock transition due to the ion-ion two-stream Weibel instability. The normalized magnetic field strength strongly correlates with the Alfvénic Mach number. Mock spacecraft measurements derived from particle-in-cell simulations are fully consistent with those taken in situ at Saturn's bow shock by the Cassini spacecraft.