Modeling spectra of the north and south Jovian X-ray auroras

• Published in: Journal of Geophysical Research - Space Physics Vol. 113; no. A8; pp. A08229 - n/a
• Main Authors: Kharchenko, V., Bhardwaj, Anil, Dalgarno, A., Schultz, D. R., Stancil, P. C.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01-08-2008; Blackwell Publishing Ltd
• Subjects: charge-exchange mechanism; Earth sciences; Earth, ocean, space; Exact sciences and technology; Ionosphere; Jovian X-ray auroral emission; Jupiter; Particle precipitation; Planetary Sciences; Radiation processes; Solar Physics, Astrophysics, and Astronomy; Solar System Objects; Space Plasma Physics; X-rays; X-rays, gamma rays, and neutrinos; polar regions; South Pole; Antarctica; North Pole; Arctic region; Jovian X-ray auroral emission; charge-exchange mechanism; X-rays; atmosphere; Energetics; models; cross sections; Load distribution; Charge exchange; kinetic energy; Monte Carlo analysis; abundance; X-ray spectra; Cross section (collision); Modeling; intensity; Electron capture; Relaxation; Aurorae; extreme value; Ionization; radiation; ions; Polar region; oxygen; X ray emission
• ISSN: 0148-0227; 2156-2202
• DOI: 10.1029/2008JA013062

Spectra of Jovian X‐ray auroras observed from the North and South poles with the Chandra X‐ray telescope are analyzed and compared with predicted spectra of the charge‐exchange mechanism. To determine the theoretical spectra of Jovian X‐ray auroras, we model numerically the collisionally induced evolution of energy and charge distributions of Oq+ and Sq+ ions, precipitating into the Jovian atmosphere. Monte Carlo simulations of the energy and charge relaxation of the precipitating ions are carried out with updated cross‐sections of the ion stripping, electron capture, and gas‐ionization collisions. X‐ray and Extreme Ultraviolet (EUV) spectra of cascading radiation induced by individual energetic sulfur and oxygen ions are calculated, and relative intensities of X‐ray emission lines are determined. Synthetic spectra of X‐ray and EUV photons are computed at different initial kinetic energies and compositions of ion‐precipitating fluxes. Theoretical spectra with adjustable initial energies and relative fraction of sulfur and oxygen ions are shown to be in good agreement with the spectra of X rays detected from the South and North polar regions. The abundances and initial energies of the precipitating ions are inferred by comparing synthetic and observed X‐ray spectra. Comparisons are performed independently for the North and South pole emissions. Abundances of the precipitating sulfur ions are found to be four to five times smaller than those of oxygen ions, and averaged ion energies are determined to lie between 1 and 2 MeV/amu. Slightly different ion flux compositions are found to describe the observed spectra of X‐ray emission from the North and South poles.