Energetic proton acceleration by EMIC waves in Io’s footprint tail

In this study, we present a survey of energetic proton observations associated with Io’s footprint tail (FPT) and compare their signatures in situ measurements the plasma waves lower-energy electron environments. We find further supporting evidence that acceleration FPT is likely consequence wave–particle interactions via electromagnetic ion cyclotron are generated by precipitating electrons into Jupiter’s ionosphere. This idea was originally proposed Clark et al. (2020) Sulaiman based on NASA’s Juno mission transiting Main Alfvén Wing (MAW) during its twelfth orbit (i.e., PJ12). Additionally, analysis > 50 keV protons presented here highlights important observational details about Io–Jupiter interaction as follows: 1) persistent feature energy flux carried highest at smaller Io-Alfvén distances; 2) exhibit positive correlations both <100 keV/Q electrons; 3) small number Io crossings, display finer spatial/temporal structure reminiscent reported Szalay (2018) ; 4) pitch angle distributions characterized two types: conic or near MAW isotropic elsewhere.