Reconnection-induced Electron Energization in Magnetospheric Kelvin-Helmholtz Dynamics
Abstract
The Kelvin--Helmholtz instability (KHI) is a major driver of multiscale plasma dynamics at velocity shear layers, where it can promote the formation of current sheets and the onset of magnetic reconnection and drive plasma energization. While recent kinetic studies have shown efficient electron heating during nonlinear KH evolution, the connection between reconnection dynamics and localized electron energization is still not fully understood. We investigate this link using 2D fully kinetic simulations of KHI developing in a double-periodic system with two velocity shear layers and a uniform guide field, initialized from a finite Larmor radius equilibrium. During the nonlinear stage, initially coherent vortices evolve into layers populated by fragmented current sheets containing active magnetic reconnection sites. The global energetics reveal distinct species-dependent energization pathways. Ions act as the primary energy reservoir, transferring energy to the electromagnetic fields, while electrons receive the dominant net positive energy input. Electron energization is strongly anisotropic (T∥,e > T⊥,e) and localized within intermittent reconnecting current sheets associated with enhanced field--particle energy exchange and elevated agyrotropy. These regions also show the development of suprathermal tails in the electron energy distributions, providing evidence for nonthermal electron energization. Despite opposite vorticity orientations, the two shear layers exhibit similar statistical behavior. Together, these results establish a direct connection between reconnection-associated current structures and localized electron energization in collisionless KHI dynamics.
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BibTeX
@article{ferro2026reconnectioninduced,
title = {{Reconnection-induced Electron Energization in Magnetospheric Kelvin-Helmholtz Dynamics}},
author = {Silvia Ferro and Fabio Bacchini and Giuseppe Arrò and Francesco Pucci and P. Henri},
journal = {The Astrophysical Journal Letters},
year = {2026},
month = sep,
doi = {10.3847/2041-8213/ae99ca},
eprint = {2606.21293},
archivePrefix = {arXiv},
url = {https://insu.hal.science/insu-05735193v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Reconnection-induced Electron Energization in Magnetospheric Kelvin-Helmholtz Dynamics
AU - Silvia Ferro
AU - Fabio Bacchini
AU - Giuseppe Arrò
AU - Francesco Pucci
AU - P. Henri
PY - 2026
DA - 2026/09/02
JO - The Astrophysical Journal Letters
DO - 10.3847/2041-8213/ae99ca
UR - https://insu.hal.science/insu-05735193v1
AB - The Kelvin--Helmholtz instability (KHI) is a major driver of multiscale plasma dynamics at velocity shear layers, where it can promote the formation of current sheets and the onset of magnetic reconnection and drive plasma energization. While recent kinetic studies have shown efficient electron heating during nonlinear KH evolution, the connection between reconnection dynamics and localized electron energization is still not fully understood. We investigate this link using 2D fully kinetic simulations of KHI developing in a double-periodic system with two velocity shear layers and a uniform guide field, initialized from a finite Larmor radius equilibrium. During the nonlinear stage, initially coherent vortices evolve into layers populated by fragmented current sheets containing active magnetic reconnection sites. The global energetics reveal distinct species-dependent energization pathways. Ions act as the primary energy reservoir, transferring energy to the electromagnetic fields, while electrons receive the dominant net positive energy input. Electron energization is strongly anisotropic (T∥,e > T⊥,e) and localized within intermittent reconnecting current sheets associated with enhanced field--particle energy exchange and elevated agyrotropy. These regions also show the development of suprathermal tails in the electron energy distributions, providing evidence for nonthermal electron energization. Despite opposite vorticity orientations, the two shear layers exhibit similar statistical behavior. Together, these results establish a direct connection between reconnection-associated current structures and localized electron energization in collisionless KHI dynamics.
SN - 2041-8205
SN - 2041-8213
ER -