08.03.2024 / 10:30 - 12:00 / Zeuthen, SR 5 | Villa

Astroparticle Physics Seminar

Energy partition in transrelativistic high Mach number collisionless shocks

Arno Vanthieghem

Collisionless shock waves shape the nonthermal emission in a wide range of environments, including modern laboratory experiments and astrophysical outflows ranging from non-relativistic supernova remnants to ultra-relativistic jets from binary neutron-star mergers. In weakly magnetized plasma flows, self-generated nonlinear electromagnetic plasma processes are inferred to heat and accelerate particles. Understanding the mechanisms that underpin the energy transfer between plasma species and the downstream temperature ratio between electrons and ions constitutes a fundamental challenge in modeling such blast waves. In this talk, I will outline recent theoretical efforts to model the transport of electrons in Weibel-mediated shocks. I will introduce a new theoretical model, supported by kinetic numerical simulations, accounting for electron heating in an ambipolar-type process through the interplay between effective pitch-angle scattering in the microturbulence and the coherent ambipolar field induced by the difference in inertia between species. I will discuss the electron-ion energy partition in the downstream of very high Alfvén Mach numbers shocks in the transrelativistic regime, the impact of subsequent larger-scale dominant modes, and implications of this model on electron injection in nonthermal distributions.

Mehr Informationen: https://indico.desy.de/category/698/