Auroral Emissions on Ganymede: New Constraints on Their Electron Energy Dependence

Abstract Auroral emissions on Ganymede provide critical insights into its magnetospheric dynamics and atmospheric composition. Using a physics‐based atmospheric model with recent atmospheric observations and laboratory measurements of electron‐impact cross‐sections, this study revisits and significantly refines the relationship between auroral emission intensities and impacting electron energies. The improvements in predicted auroral brightness include: the peak intensity at 135.6 nm is significantly higher than previous estimates, and the threshold electron energies necessary for intense auroral brightness (>300 Rayleighs) decrease to ∼50–60 eV, resolving previous theoretical challenges. Our refined model also demonstrates the spatial dependence of the emission‐energy relation. In particular, we highlight how incorporating these updated inputs reshapes the energy dependence relationship, enhancing consistency with recent high‐resolution UV observations. These refined constraints not only advance our understanding of Ganymede's aurora and its interaction with Jupiter's magnetosphere, but also improve the interpretive framework for future in situ missions, by spacecraft such as JUICE.