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. 2021 Jul 9;7(28):eabf0851.
doi: 10.1126/sciadv.abf0851. Print 2021 Jul.

Revealing the source of Jupiter's x-ray auroral flares

Zhonghua Yao  1   2 , William R Dunn  3   4   5 , Emma E Woodfield  6 , George Clark  7 , Barry H Mauk  7 , Robert W Ebert  8   9 , Denis Grodent  10 , Bertrand Bonfond  10 , Dongxiao Pan  11 , I Jonathan Rae  12 , Binbin Ni  13   14 , Ruilong Guo  10 , Graziella Branduardi-Raymont  3 , Affelia D Wibisono  3   5 , Pedro Rodriguez  15 , Stavros Kotsiaros  16 , Jan-Uwe Ness  15 , Frederic Allegrini  8   9 , William S Kurth  17 , G Randall Gladstone  8   9 , Ralph Kraft  4 , Ali H Sulaiman  17 , Harry Manners  18 , Ravindra T Desai  18 , Scott J Bolton  8
Affiliations

Revealing the source of Jupiter's x-ray auroral flares

Zhonghua Yao et al. Sci Adv. .

Abstract

Jupiter's rapidly rotating, strong magnetic field provides a natural laboratory that is key to understanding the dynamics of high-energy plasmas. Spectacular auroral x-ray flares are diagnostic of the most energetic processes governing magnetospheres but seemingly unique to Jupiter. Since their discovery 40 years ago, the processes that produce Jupiter's x-ray flares have remained unknown. Here, we report simultaneous in situ satellite and space-based telescope observations that reveal the processes that produce Jupiter's x-ray flares, showing surprising similarities to terrestrial ion aurora. Planetary-scale electromagnetic waves are observed to modulate electromagnetic ion cyclotron waves, periodically causing heavy ions to precipitate and produce Jupiter's x-ray pulses. Our findings show that ion aurorae share common mechanisms across planetary systems, despite temporal, spatial, and energetic scales varying by orders of magnitude.

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Figures

Fig. 1
Fig. 1. Juno and XMM measurement comparison.
(A) Juno MAG measurements of the field-aligned magnetic component (B∥) in mean field–aligned coordinates (coordinates obtained over a 60-min window). (B) Power spectral density of the magnetic field perturbations with the gyro frequencies of various charge states of ions (He+, O++, O+, and S+) overlaid. (C) Degree of polarization of the waves. (D) Wave ellipticity. (E) Wave normal angle. (F) Juno JEDI measurements of the sulfur and oxygen energy and intensity. (G) XMM EPIC-pn and MOS light curves (binned to a resolution of 4 min) from the north x-ray aurora, which was observable at this time. The x-ray light curve has been shifted to account for the light travel time from Jupiter to XMM. Blue dashed lines show the times of EMIC waves. The time taken to precipitate along the magnetic field lines from the outer magnetosphere is expected to be tens of minutes or more so that it is not possible to directly connect a single EMIC wave with an x-ray pulse; however, they both exhibit similar quasi-periodicity.
Fig. 2
Fig. 2. A schematic to illustrate the wave-particle interaction and the consequent x-ray emissions.
Fig. 3
Fig. 3. The comparison of periodicity for x-ray and magnetic field for 2.6 Jupiter rotations.
(A) Detrended field-aligned magnetic field component (black) and northern x-ray emission (red). Lomb-Scargle periodograms of the detrended field-aligned magnetic field B∥ (B) and northern x-ray emission (C) for three intervals marked by the blue bars on the top. The red dashed lines indicate the confidence level of 95% for each analysis. The blue dashed vertical lines show shared x-ray and magnetic field power spectral density (PSD) periodogram peaks.
Fig. 4
Fig. 4. Local pitch angle diffusion coefficients Dαα for sulfur and oxygen ions.
The diffusion coefficients Dαα are calculated using the PADIE code (see the Supplementary Materials) from a combination of H+, O+ (or S++), and S+ waves calculated locally at B ~ 6 and 3 nT, respectively, interacting with O+ (or S++) and S+ ions. The black numbers above the x axis show the maximum latitude a particle with this pitch angle will reach before mirroring. The left panels show the wave interaction with O+ (or S++) ions, and the right panels show the interaction with S+ ions.
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References

    1. Branduardi-Raymont G., Elsner R. F., Galand M., Grodent D., Cravens T. E., Ford P., Gladstone G. R., Waite J. H. Jr., Spectral morphology of the x-ray emission from Jupiter’s aurorae. J. Geophys. Res. Space Phys. 113, A02202 (2008).
    1. Cravens T. E., Howell E., Waite J. H. Jr., Gladstone G. R., Auroral oxygen precipitation at Jupiter. J. Geophys. Res. Space Phys. 100, 17153–17161 (1995).
    1. Metzger A. E., Gilman D. A., Luthey J. L., Hurley K. C., Schnopper H. W., Seward F. D., Sullivan J. D., The detection of x-rays from Jupiter. J. Geophys. Res. Space Phys. 88, 7731–7741 (1983).
    1. Dunn W., Branduardi-Raymont G., Ray L. C., Jackman C. M., Kraft R. P., Elsner R. F., Rae I. J., Yao Z., Vogt M. F., Jones G. H., Gladstone G. R., Orton G. S., Sinclair J. A., Ford P. G., Graham G. A., Caro-Carretero R., Coates A. J., The independent pulsations of Jupiter’s northern and southern x-ray auroras. Nat. Astron. 1, 758–764 (2017).
    1. Gladstone G., Waite J. H. Jr., Grodent D., Lewis W. S., Crary F. J., Elsner R. F., Weisskopf M. C., Majeed T., Jahn J.-M., Bhardwaj A., Clarke J. T., Young D. T., Dougherty M. K., Espinosa S. A., Cravens T. E., A pulsating auroral x ray hot spot on Jupiter. Nature 415, 1000–1003 (2002). - PubMed