Reconnection Rate & Off-Diagonal Pressure: Comparing Electron-Only Reconnection & Current Sheets to Ion-Coupled Electron Diffusion Regions in Earth's Magnetotail

Magnetic reconnection is a ubiquitous process in solar and magnetospheric plasmas and the origin of explosive phenomena across the Solar System. Electron-only (EO) reconnection is a newly observed form of reconnection driven by electron kinetics but lacking coincident ion response. Recently, EO reconnection and super thin current sheets (STCS), with thicknesses less than 10 electron inertial lengths, were identified in Earth's magnetotail. It has been proposed that EO reconnection in Earth's magnetosheath exhibits a significantly higher reconnection rate than its ion-coupled counterpart. This has not yet been observationally investigated in the magnetotail. In addition, it was previously unclear if electron-scale, non-reconnecting current sheets and ion-coupled electron diffusion regions (EDRs) display similar off-diagonal gradients in the electron-pressure tensor, temperature profiles, and number density profiles. In this work, we use data from the Magnetospheric Multiscale (MMS) Mission to identify electron-scale current sheets, EO reconnection, and ion-coupled EDRs in Earth's magnetotail. Using these direct observations, we calculate and directly compare the reconnection rates of EO reconnection and EDR events. We also compare the diagonal/off-diagonal terms of the pressure tensor of electron-scale quiet current sheets and EDRs. We find that electrons are significantly heated relative to the surrounding plasma sheet in EO reconnection and EDRs, but not in quiet, electron-scale current sheets. We also find that the plasma density within the EDR decreases at the current-sheet center for crossings primarily in the outflow direction and remains constant at the current-sheet center for crossings primarily in the current-sheet normal direction. Meanwhile, quiet current sheets and EO reconnection events display increased plasma density at the reconnection center. This examination of plasma and field properties helps us to better distinguish the anatomies of non-reconnecting and reconnecting electron-scale current sheets.