Electron distribution in the Jovian inner magnetosphere derived from multiple observations

Jupiter forms the largest magnetosphere in the solar system, covering an area nearly 100 times the radius of Jupiter. Jupiter's magnetosphere has been observed by various instruments, including the HISAKI satellite and the Juno spacecraft. The HISAKI satellite observes Jupiter and its surrounding region out to ~8 R_J with a fixed field of view while orbiting the Earth. The Juno spacecraft, on the other hand, directly observes a wide area of the magnetosphere while orbiting Jupiter. It has been suggested that energy supplied by the solar wind and Jupiter's interior is stored in the outer magnetosphere and rapidly released by reconnection, causing plasma to flow toward Jupiter (Tao et al., 2018). In addition, previous studies have shown that volcanic activity on Jupiter's moon Io plays an important role in supplying the material that accumulates within Jupiter's magnetosphere, and data from the HISAKI satellite reinforces this understanding (Yoshioka et al., 2017). Continuous observations of Io's activity and the distant magnetosphere would clarify the impact of Io on Jupiter's magnetosphere and lead to a better understanding of the energy transport process in the magnetosphere. Therefore, in this study, we compare observation data from the HISAKI and Juno spacecraft to describe the average distribution of energy and density of Io-derived plasma particles as a function of distance from Jupiter (i.e., M-shell) in the vast magnetosphere. The electron temperature, electron density, and ion density were derived by fitting spectra obtained from remote sensing by the HISAKI satellite with a model using the atomic database CHIANTI. The orbital electron distribution was also obtained from particle measurement data obtained by in-situ observation of Juno, as being published by Sarkango et al. 2025. We focus our comparison on the plasma parameter distributions obtained from the HISAKI observation data and the Juno JADE instrument in the period when the observation areas of the two spacecrafts nearly overlap.