Electron Heating in Perpendicular Low-Beta Shocks

Abstract

Collisionless shocks heat electrons in the solar wind, interstellar blast waves, and hot gas permeating galaxy clusters. How much shock heating goes to electrons instead of ions, and what plasma physics controls electron heating? We simulate 2-D perpendicular shocks with a fully kinetic particle-in-cell code. For magnetosonic Mach number ${\mathcal{M}}_{\mathrm{ms}}\sim 1$-$10$ and plasma beta ${\beta }_{\mathrm{p}}\lesssim 4$, the post-shock electron/ion temperature ratio $T_{\mathrm{e}}/T_{\mathrm{i}}$ decreases from $1$ to $0.1$ with increasing ${\mathcal{M}}_{\mathrm{ms}}$. In a representative ${\mathcal{M}}_{\mathrm{ms}}=3.1$, ${\beta }_{\mathrm{p}}=0.25$ shock, electrons heat above adiabatic compression in two steps: ion-scale $E_{\parallel }=\vec{E}\cdot \hat{b}$ accelerates electrons into streams along $\vec{B}$, which then relax via two-stream-like instability. The $\vec{B}$-parallel heating is mostly induced by waves; $\vec{B}$-perpendicular heating is mostly adiabatic compression by quasi-static fields.

arXiv commentAccepted ApJL; 15 pages, 9 figures with references and appendices. Movies, figure sets, table CSV at http://user.astro.columbia.edu/~atran/share/arxiv/2002.11132/ . v3: replace sum(<E>*<v>) with drift work analysis

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Cited by in corpus (16)

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• Particle energization in relativistic plasma turbulence: solenoidal versus compressive driving
• Theory of Electron Injection at Oblique Shock of Finite Thickness
• Kinetic simulation of nonrelativistic perpendicular shocks of young supernova remnants. IV. Electron heating
• Double layers in the Earth's bow shock
• Cosmic-ray electrons released by supernova remnants
• A formation mechanism for "Wrong Way" Radio Relics
• Electron heating in high Mach number collisionless shocks
• The maximum energy of shock-accelerated electrons in a microturbulent magnetic field
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• Electron Heating in 2D Particle-in-Cell Simulations of Quasi-Perpendicular Low-Beta Shocks
• Kinetic Simulations of Strongly-Magnetized Parallel Shocks: Deviations from MHD Jump Conditions
• Radio Nebulæ from Hyper-Accreting X-ray Binaries as Common Envelope Precursors and Persistent Counterparts of Fast Radio Bursts