Identifying the Growth Phase of Magnetic Reconnection using Pressure-Strain Interaction

TL;DR

This paper introduces a new indicator based on pressure-strain interaction structures to identify the growth phase of magnetic reconnection, validated through simulations and potentially observable by spacecraft.

Contribution

It proposes a novel pressure-strain interaction signature as an indicator of the reconnection growth phase, validated with particle-in-cell simulations.

Findings

Pressure-strain interaction structures mark the growth phase.

Signature detectable with multi-spacecraft measurements.

Validated using 2D particle-in-cell simulations.

Abstract

Magnetic reconnection often initiates abruptly and then rapidly progresses to a nonlinear quasi-steady state. While satellites frequently detect reconnection events, ascertaining whether the system has achieved steady-state or is still evolving in time remains challenging. Here, we propose that the relatively rapid opening of reconnection separatrices within the electron diffusion region (EDR) serves as an indicator of the growth phase of reconnection. The opening of the separatrices is produced by electron flows diverging away from the neutral line downstream of the X-line and flowing around a dipolarization front. This flow pattern leads to characteristic spatial structures in pressure-strain interaction that could be a useful indicator for the growth phase of a reconnection event. We employ two-dimensional particle-in-cell numerical simulations of anti-parallel magnetic reconnection to validate this prediction. We find that the signature discussed here, alongside traditional reconnection indicators, can serve as a marker of the growth phase. This signature is potentially accessible using multi-spacecraft single-point measurements, such as with NASA's Magnetospheric Multiscale (MMS) satellites in Earth's magnetotail. Applications to other settings where reconnection occurs are also discussed.