Energetic electrons in the inner part of the Jovian magnetosphere and their relation to auroral emissions

The energetic particle distribution in the magnetosphere of Jupiter changes significantly between the inner and the middle magnetosphere. One of the most prominent changes is a transition of the electron pitch angle distribution (PAD) from a pancake to a bidirectional distribution. The transition is a persistent and localized feature defining a distinct spatial boundary between 10 and 17 RJ. We discuss the possible relation between the PAD boundary and some of the observed structures in the Jovian aurora. A comparison between the Hubble Space Telescope observations and the predicted ionospheric footprints of the PAD boundary indicates a good correlation, with a discrete belt of emissions equatorward of the main auroral oval. Furthermore, the precipitation energy flux associated with the energetic electron distribution at the PAD boundary is compatible with the brightness range of these auroral emissions.