On the Electron Agyrotropy during Rapid Asymmetric Magnetic Island Coalescence in Presence of a Guide Field

TL;DR

This paper investigates electron velocity distribution properties during magnetic island coalescence in asymmetric reconnection, highlighting differences in agyrotropy with and without guide fields and analyzing phase-space structures.

Contribution

It provides a comparative analysis of electron agyrotropy metrics in the presence of guide fields and introduces new insights into electron phase-space behavior during reconnection.

Findings

Discrepancies in agyrotropy metrics with guide field presence.

Identification of electron phase-space structures in reconnection regions.

Differences in electron behavior at separatrices and within magnetic islands.

Abstract

We present an analysis of the properties of the electron velocity distribution during island coalescence in asymmetric reconnection with and without guide field. In a previous study, three main domains were identified, in the case without guide field, as X-, D- and M-regions featuring different reconnection evolutions {Cazzola et al. 2015). These regions are also identified here in the case with guide field. We study the departure from isotropic and gyrotropic behavior by means of different robust detection algorithms proposed in the literature. While in the case without guide field these metrics show an overall agreement, when the guide field is present a discrepancy in the agyrotropy within some relevant regions is observed, such as at the separatrices and inside magnetic islands. Moreover, in light of the new observations from the Multiscale MagnetoSpheric mission, an analysis of the electron velocity phase-space in these domains is presented.