Uncovering local magnetospheric processes governing the morphology and variability of Ganymede's aurora using three-dimensional multifluid simulations of Ganymede's magnetosphere

摘要

We investigate local magnetospheric processes governing the morphology and variability of Ganymede's aurora depending on its position with respect to the center of the Jovian plasma sheet. We couple an existing three-dimensional multifluid simulation to a new aurora brightness model developed for this study. With this, we are able to qualitatively and quantitatively show that the short- and long-period variabilities observed in Ganymede's auroral footprint at Jupiter are also predicted to be present in the brightness and morphology of the aurora at Ganymede. We also examine the relationship between acceleration structures and precipitation of electrons in Ganymede's neutral atmosphere by looking at the component of the electric field parallel to Ganymede's magnetic field. Our results confirm that regions of electron accelerations coincide with regions of brightest auroral emissions, as expected. Finally, we identify the likely source regions of electrons generating the aurora at Ganymede and discuss the plasma dynamic mechanisms likely responsible for these accelerations.