Evidence for the dissipation region in magnetotail reconnection

TL;DR

This study uses spacecraft data and simulations to identify and analyze the dissipation region in magnetotail magnetic reconnection, providing new measures to understand the reconnection process.

Contribution

The paper introduces a novel dissipation measure D*_e validated by simulations, enabling direct detection of the dissipation region in space plasma data.

Findings

D*_e successfully detects the dissipation region near the X-point.

The dissipation rate is estimated at 45 pW/m^3.

The dissipation region length is 1-2 ion inertial lengths.

Abstract

Signatures of the dissipation region of collisionless magnetic reconnection are investigated by the Geotail spacecraft for the 15 May 2003 event. The energy dissipation in the rest frame of the electron's bulk flow is considered in an approximate form D*_e, which is validated by a particle-in-cell simulation. The dissipation measure is directly evaluated from the {plasma moments}, the electric field, and the magnetic field. Using D*_e, a compact dissipation region is successfully detected in the vicinity of the possible X-point in Geotail data. The dissipation rate is 45 pWm**{-3}. The length of the dissipation region is estimated to 1--2 local ion inertial length. The Lorentz work W, the work rate by Lorentz force to plasmas, is also introduced. It is positive over the reconnection region and it has a peak around the pileup region away from the X-point. These new measures D*_e and W provide useful information to understand the reconnection structure.