Characterizing Precipitating Electrons in Ganymede's Auroras through Juno/UVS observations and Coupled Electron Transport and Radiative Transfer Models

Auroral emissions offer crucial insights into the coupling between planetary magnetic fields, atmospheres, and surrounding plasma. While Jupiter's aurorae are well studied, those of Ganymede, the only moon with an intrinsic magnetic field, remain less understood. Observations by the Hubble Space Telescope (HST) and Juno/UVS have revealed UV auroral ovals on Ganymede, shaped by its interaction with Jupiter's magnetosphere and associated with atomic oxygen emissions at 130 and 135 nm. While these emissions, originate from electron impact excitation of oxygenated species such as H₂O, O, and O₂, are clearly detected, the energy and distribution of the precipitating electrons responsible remain poorly constrained. Building on our previous work on Jupiter's aurorae (Benmahi et al. 2024a,b), we applied a similar methodology to Ganymede, focusing on emissions in the 125-135 nm range. Using our electron transport model TransPlanet coupled with a custom non-LTE radiative transfer model, we reproduced the OI 130 and 135 nm emissions observed by Juno/UVS during the PJ34 flyby, across sunlit regions 0 to 16.