Electron heating mechanisms at quasi-perpendicular shocks - revisited with magnetospheric multiscale measurements

Stasiewicz, Krzysztof and Eliasson, Bengt (2023) Electron heating mechanisms at quasi-perpendicular shocks - revisited with magnetospheric multiscale measurements. Monthly Notices of the Royal Astronomical Society, 520 (3). pp. 3238-3244. ISSN 0035-8711 (https://doi.org/10.1093/mnras/stad361)

[thumbnail of Stasiewicz-Eliasson-MNRSA-2023-Electron-heating-mechanisms-at-quasi-perpendicular-shocks-revisited]
Preview
Text. Filename: Stasiewicz_Eliasson_MNRSA_2023_Electron_heating_mechanisms_at_quasi_perpendicular_shocks_revisited.pdf
Final Published Version
License: Creative Commons Attribution 4.0 logo

Download (1MB)| Preview

Abstract

We demonstrate that measurements obtained from NASA's Magnetospheric Multiscale (MMS) mission support quasi-adiabatic electron heating in quasi-perpendicular shocks with temperature ⊥ ∝ ^(1+), where is the magnetic field strength and represents departure from adiabaticity. Adiabatic heating ( = 0) results from the conservation of magnetic moment on spatially increasing magnetic field inside the shock ramp. Negative < 0 is observed in most situations, where perpendicular energy gain from adiabatic heating is redistributed by interactions with waves to the parallel direction leading to a lower isotropic temperature increase. Positive is observed when the stochastic heating of electrons is activated by the × wave acceleration mechanism by electrostatic waves leading to a higher temperature increase. By using test-particle simulations in a realistic shock model we have elucidated the process of stochastic wave acceleration. We have also shown the equivalence of adiabatic heating and acceleration by gradient drift at shocks with low Mach numbers and demonstrated that the cross-shock potential does not contribute to the electron heating. Signatures of quasi-adiabatic heating, and/or stochastic heating of electrons are observed in all shocks analysed with measurements by the MMS.

ORCID iDs

Stasiewicz, Krzysztof and Eliasson, Bengt ORCID logoORCID: https://orcid.org/0000-0001-6039-1574;