Proton-Induced X-ray Emission (PIXE) from the Galilean Satellites: Modeling charged-particle interactions on the satellite surfaces and the prospect for direct measurement of the elemental compositions

Abstract:

Energetic particles in the Jovian magnetosphere impact the surface of the Galilean moons and
generate characteristic X-ray lines from the elemental constituents due to the proton-induced
X-ray emission (PIXE) process. The X-ray spectra of these satellites provide direct measurements
of their elemental surface compositions. Chandra X-ray Observatory (CXO) observations
of Jupiter detected oxygen emission from Io and Europa (Elsner et al. 2005). We present
calculations of the expected PIXE from each of the Galilean satellites for various models of
their surface constituents. We discuss the viability of detecting emission lines from
elements other than oxygen with deep observations from the current generation of Earth-orbiting X-ray observatories,
and describe the implications to our understanding of the surface processes from such
detections. Finally, we outline the potential discovery space for a dedicated X-ray imaging
spectrometer flown on a mission to the Jovian system.