Reconnection-driven Dynamics at Ganymede’s Upstream Magnetosphere: 3D
Global Hall MHD and MHD-EPIC Simulations
Abstract
The largest moon in the solar system, Ganymede, is the only moon known
to possess a strong intrinsic magnetic field and a corresponding
magnetosphere.
Using the latest version of Space Weather Modeling Framework (SWMF), we
study the upstream plasma interactions and dynamics in this sub-Alfvenic
system.
Results from the Hall MHD and the coupled MHD with embedded
Particle-in-Cell (MHD-EPIC) models are compared.
We find that under steady upstream conditions, magnetopause reconnection
occurs in a non-steady manner.
Flux ropes of Ganymede’s radius in length form on the magnetopause at a
rate about 2/minute and create spatiotemporal variations in plasma and
field properties.
Upon reaching proper grid resolutions, the MHD-EPIC model can resolve
both electron and ion kinetics at the magnetopause and show localized
non-gyrotropic behavior inside the diffusion region.
The estimated global reconnection rate from the models is about 80 kV
with 60% efficiency, and there is weak evidence of about 1 minute
periodicity in the temporal variations due to the dynamic reconnection
process.