NEWS & EVENTS

Jupiter is the most powerful natural particle accelerator in the Solar System and emits X-rays from both its aurorae and its surrounding space environment. Despite decades of X-ray observations, for example with Chandra and XMM-Newton, there are still major open questions about the physical mechanisms that produce these emissions and about the processes that control their time variability. A key part of Jupiter’s inner magnetosphere is the Io Plasma Torus (IPT). Volcanic activity on the Galilean moon Io continuously supplies material, primarily sulfur and oxygen-bearing neutrals, forming an extended neutral cloud around Jupiter. Through photoionization and electron impact ionization this material becomes ionized and is captured by Jupiter’s strong magnetic field, producing a dense, toroidal plasma distribution that co-rotates with the planet. The IPT’s X-ray emission is intrinsically faint, and multiple candidate mechanisms can contribute at overlapping energies, making them difficult to disentangle from Earth-based observations alone. In this work, I am developing physics-based model of IPT X-ray production that links plausible plasma conditions, including composition, ionization state, density, temperature, and energetic particle populations, to predicted spectra and brightness. Constraining this emission improves our understanding of magnetospheric plasma physics and helps characterize Jupiter’s hostile, high-radiation environment, which is relevant for future missions and potential X-ray instrumentation in the Jovian system.

Jupiter’s aurorae also exhibit a distinct X-ray component that is highly time-variable and often quasi-periodic. Longer-period pulsations, including the well-known 20 to 45 minute periodicity, are comparatively well studied, but shorter-timescale components, such as around 4 minute and sub 15-minute pulsations, have only been reported intermittently and remain poorly constrained. I develop and apply a new dynamic binning technique to search for these quasi-periodic signatures in XMM-Newton observations, designed to improve sensitivity to transient or evolving periodicities that may be missed by fixed time binning. I then compare the timing of any detections with in-situ measurements from Juno to investigate plausible magnetospheric drivers, such as changes in particle populations or wave activity. Together, modelling IPT X-ray emission and probing auroral pulsations strengthens the link between remote X-ray observations and Jupiter’s plasma environment and provides improved diagnostic tools for interpreting Jovian X-ray phenomenology.

For additional information, please contact Mr. Fenn Peter Leppard,  fleppard@connect.hku.hk.