# Studying dawn-dusk asymmetries of Mercury's magnetotail using MHD-EPIC simulations

## TL;DR

This study uses advanced MHD-EPIC simulations to explore dawn-dusk asymmetries in Mercury's magnetotail, revealing that the dawnside exhibits thicker current sheets, higher plasma density, and more frequent reconnection events, aligning with MESSENGER data.

## Contribution

It provides the first comprehensive global simulation of Mercury's magnetotail asymmetries using MHD-EPIC, linking observed dawn-dusk differences to plasma dynamics and reconnection processes.

## Key findings

- Dawnside current sheet is thicker and denser.
- Reconnection sites favor the dawnside under strong IMF.
- Dipolarization events and electron jets are dawnward-moving.

## Abstract

MESSENGER has observed a lot of dawn-dusk asymmetries in Mercury's magnetotail, such as the asymmetries of the cross-tail current sheet thickness and the occurrence of flux ropes, dipolarization events and energetic electron injections. In order to obtain a global pictures of Mercury's magnetotail dynamics and the relationship between these asymmetries, we perform global simulations with the magnetohydrodynamics with embedded particle-in-cell (MHD-EPIC) model, where Mercury's magnetotail region is covered by a PIC code. Our simulations show that the dawnside current sheet is thicker, the plasma density is larger, and the electron pressure is higher than the duskside. Under a strong IMF driver, the simulated reconnection sites prefer the dawnside. We also found the dipolarization events and the planetward electron jets are moving dawnward while they are moving towards the planet, so that almost all dipolarization events and high-speed plasma flows concentrate in the dawn sector. The simulation results are consistent with MESSENGER observations.