Multi-fluid Simulations of Ganymede's Magnetosphere: The Role of Heavy Ions in the Magnetotail

The magnetosphere of Ganymede, embedded in the Jovian magnetosphere, presents us with a unique case study of a sub-alfvenic flow interaction in the presence of continuous reconnection. We study the interaction using multi-fluid simulations that have been benchmarked against existing magnetometer data and UV observation. These simulations are a useful tool in determining the role of heavy ions, present from both the ionosphere of Ganymede and the corotational magnetosphere of Jupiter, in the tail region of Ganymede. Heavy ions are important not only for energy and momentum transport in the magnetosphere, but are also required to precipitate through the tenuous atmosphere and sputter the icy surface of Ganymede. It is shown that heavy ions from Ganymede's magnetosphere are accelerated via reconnection in the tail and enabled to precipitate down to the surface on the leading hemisphere (tail side). Incident plasma from Jupiter's magnetosphere is also heated and precipitates on both the flow facing (trailing) and tail (leading) hemispheres. Polar outflow of Ganymede's ionosphere was also studied and found to contribute significantly to the local population of Jupiter's magnetosphere.