2D reconstruction of magnetotail electron diffusion region measured by MMS

TL;DR

This paper analyzes in situ spacecraft data from Earth's magnetotail to validate 2D kinetic models of magnetic reconnection, showing that the observed electron diffusion region aligns with 2D simulations despite potential 3D perturbations.

Contribution

The study provides the first in situ validation of 2D kinetic reconnection models in Earth's magnetotail, bridging observational data and theoretical simulations.

Findings

Electron diffusion region structure matches 2D kinetic simulation results.

Event likely influenced by 3D dynamics but remains consistent with 2D models.

Validates the applicability of 2D laminar reconnection models in space plasma.

Abstract

Models for collisionless magnetic reconnection in near-Earth space are distinctly characterized as 2D or 3D. In 2D kinetic models, the frozen-in law for the electron fluid is usually broken by laminar dynamics involving structures set by the electron orbit size, while in 3D models the width of the electron diffusion region is broadened by turbulent effects. We present an analysis of in situ spacecraft observations from the Earth's magnetotail of a fortuitous encounter with an active reconnection region, mapping the observations onto a 2D spatial domain. While the event likely was perturbed by low-frequency 3D dynamics, the structure of the electron diffusion region remains consistent with results from a 2D kinetic simulation. As such, the event represents a unique validation of 2D kinetic, and laminar reconnection models.