Broadband Energization of Superthermal Electrons in Jupiter's Inner Magnetosphere

The Juno spacecraft in a polar orbit around Jupiter has observed broadband electron energization signatures at high latitudes (Mauk et al., 2017, ). We investigate the origin of this energization by simulating the propagation of dispersive Alfven waves from the Io plasma torus to high latitudes. These waves may be triggered by mechanisms such as the moon-magnetosphere interaction or inflows from radial transport. We build on the initial hybrid gyrofluid-kinetic electron simulation of Damiano et al. (2019, ) to further quantify electron energization by Alfvenic waves, and investigate this process as a local source mechanism for observed broadband superthermal electron populations. We find that the magnitude of energization increases with the wave amplitude, while decreasing the radial wavelength reduces the high-latitude wave and particle energy flux. Over the examined range of initial conditions we successfully generate broadband electron populations consistent with Juno observations (Mauk et al., 2017, ; Szalay et al., 2018, ), that contribute to both precipitating populations and those that form trans-hemispheric beams. Our energized electron distributions are consistent with observed superthermal populations critical for the torus energy budget (Bagenal & Delamere, 2011, ) and Io-related auroral emission.

Automated summary

This study investigates the origin of electron energization at high latitudes of Jupiter through simulating the propagation of dispersive Alfven waves, and quantifies the impact of these waves on electron energization. It successfully generates electron populations consistent with observations, shedding light on the energy budget of the torus and Io-related auroral emissions.