Wave‐Particle Interactions Associated With Io's Auroral Footprint: Evidence of Alfvén, Ion Cyclotron, and Whistler Modes

Abstract

Abstract The electrodynamic coupling between Io and Jupiter gives rise to wave‐particle interactions across multiple spatial scales. Here we report observations during Juno's 12th perijove (PJ) high‐latitude northern crossing of the flux tube connected to Io's auroral footprint. We focus on plasma wave measurements, clearly differentiating between magnetohydrodynamic (MHD), ion, and electron scales. We find (i) evidence of Alfvén waves undergoing a turbulent cascade, suggesting Alfvénic acceleration processes together with observations of bi‐directional, broadband electrons; (ii) intense ion cyclotron waves with an estimated heating rate that is consistent with the generation of ion conics reported by Clark et al. (2020, https://doi.org/10.1029/2020GL090839 ); and (iii) whistler‐mode auroral hiss radiation excited by field‐aligned electrons. Such high‐resolution wave and particle measurements provide an insight into satellite interactions in unprecedented detail. We further anticipate that these spatially well‐constrained results can be more broadly applied to better understand processes of Jupiter's main auroral oval.