Energizing suprathermal electron populations via dispersive scale Alfvén waves at Jupiter

Abstract:

We use a self-consistent two-dimensional hybrid gyrofluid-kinetic electron (GKE) model to simulate the propagation of Alfvén wave energy along the Io flux tube and examine the resulting wave-electron interactions. At high latitudes the interaction of electrons with inertial Alfvén waves are manifest as highly field-aligned broadband electron distributions (e.g. Damiano et al., 2019) that are consistent with recent Juno observations. Post-energization, the distribution functions maintain an elongated tail suggesting that energization of trapped electrons via dispersive scale Alfvén waves can be a source of suprathermal electrons critical to the torus energy balance (Bagenal and Delamere, 2011) and the torus physical chemistry (Coffin et al, 2020). The post-energization appearance of electron beams close to the Io torus also suggests that Alfvén-wave energized electrons could be a source of the observed trans-hemispheric beams (as proposed by Bonfond et al., 2008).