Jupiter's X-ray and EUV auroras monitored by Chandra, XMM-Newton, and Hisaki satellite

Kimura, T. and Kraft, R. P. and Elsner, R. F. and Branduardi-Raymont, Graziella and Gladstone, G. R. and Tao, C. and Yoshioka, Kazuo and Murakami, G. and Yamazaki, A. and Tsuchiya, F. and Vogt, M. F. and Masters, Adam and Hasegawa, H. and Badman, Sarah Victoria and Roediger, E. and Ezoe, Y. and Dunn, W. R. and Yoshikawa, I. and Fujimoto, M. and Murray, S. S. (2016) Jupiter's X-ray and EUV auroras monitored by Chandra, XMM-Newton, and Hisaki satellite. Journal of Geophysical Research: Space Physics. pp. 2308-2320. ISSN 2169-9402

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Abstract

Jupiter's X-ray auroral emission in the polar cap region results from particles which have undergone strong field-aligned acceleration into the ionosphere. The origin of precipitating ions and electrons and the time variability in the X-ray emission are essential to uncover the driving mechanism for the high-energy acceleration. The magnetospheric location of the source field line where the X-ray is generated is likely affected by the solar wind variability. However, these essential characteristics are still unknown because the long-term monitoring of the X-rays and contemporaneous solar wind variability has not been carried out. In April 2014, the first long-term multiwavelength monitoring of Jupiter's X-ray and EUV auroral emissions was made by the Chandra X-ray Observatory, XMM-Newton, and Hisaki satellite. We find that the X-ray count rates are positively correlated with the solar wind velocity and insignificantly with the dynamic pressure. Based on the magnetic field mapping model, a half of the X-ray auroral region was found to be open to the interplanetary space. The other half of the X-ray auroral source region is magnetically connected with the prenoon to postdusk sector in the outermost region of the magnetosphere, where the Kelvin-Helmholtz (KH) instability, magnetopause reconnection, and quasiperiodic particle injection potentially take place. We speculate that the high-energy auroral acceleration is associated with the KH instability and/or magnetopause reconnection. This association is expected to also occur in many other space plasma environments such as Saturn and other magnetized rotators.