Energetic Ion Precipitation in Jupiter’s Polar Auroral Region Observed by Juno/JEDI

<p>Remote observations clearly show that soft X-ray emissions at Jupiter concentrate poleward of the main oval forming a so-called &#8220;hot spot&#8221; (Gladstone et al., 2002; Dunn et al., 2016). One hypothesis proposes that the X-rays are likely produced from precipitating energetic heavy ions that become fully stripped via interactions in Jupiter&#8217;s upper atmosphere; however, the details regarding the ion source and acceleration mechanism(s) of the soft X-ray (~2 keV) component is still an active area of research. NASA&#8217;s Juno mission &#8211; a Jupiter polar orbiting spacecraft &#8211; is shedding light onto this mystery with in situ observations of the energetic particle environment over the poles, and coordinated observing campaigns with Earth-orbiting X-ray observatories, e.g., Chandra and XMM-Newton. Recent ideas supported by Juno data include: 1) pitch angle scattering of energetic ions via electromagnetic ion cyclotron waves in the outer magnetosphere (Yao et al., 2021); and 2) acceleration of ions to several MeV over Jupiter&#8217;s poles via field-aligned electric potentials (Clark et al., 2017; Haggerty et al., 2017; Clark et al., 2020; Yao et al., 2021). New techniques have been recently developed to push the capabilities of Juno&#8217;s Jupiter Energetic particle Detector Instrument (JEDI) to measure the > 10 MeV ions (Westlake et al., 2019; Kollmann et al., 2020). In this presentation, we utilize these techniques to characterize the precipitating fluxes of > 10 MeV ions over Jupiter&#8217;s polar region with the goal of better understanding the sources of Jupiter&#8217;s X-ray auroral emissions.</p>