A review of satellite-magnetosphere interactions at Jupiter

The Galilean moons – Io, Europa, Ganymede, and Callisto, act as obstacles to the plasma flows in Jupiter’s inner magnetosphere. This interaction affects the local plasma environment of each moon and propagates along magnetic field lines to the polar regions of Jupiter’s ionosphere, producing satellite-footprint aurorae. It also provides a laboratory to study fundamental plasma physics given that the source region for these interactions is well-constrained. In this seminar, I will discuss the current state of understanding of these interactions at Jupiter, starting from early observations of Io-modulated radio emissions, theories of local plasma interaction at the moons, the first infrared and UV observations of the Io footprint aurora, theory and models of Alfvén-wave propagation within the satellite flux tubes; to recent observations made using the Juno spacecraft’s instrument suite. Over its prime and extended mission so far, Juno has made several fundamental discoveries regarding moon-magnetosphere interactions. Plasma and infrared observations have shown that the Io footprint aurora has a complex morphology, with a wavy and split tail. Juno has passed through magnetic flux tubes connected to the moons and has found intense electron and proton fluxes, and electromagnetic waves, within these short flux tube crossing intervals. The mechanism by which particles are accelerated due to the standing Alfvén wave structure remains an active area of research, although kinetic Alfvén waves and turbulence are believed to play an important role. With this context, I will also discuss new observations of energy-banded protons and electrons within the satellite flux tube crossings, which are likely related to bounce resonance with the standing Alfvén waves of the interactions, and discuss future directions of research using observations and modeling.