Abstract
AbstractTo help understand and determine the driver of jovian auroral X‐rays, we present the first statistical study to focus on the morphology and dynamics of the jovian northern hot spot (NHS) using Chandra data. The catalog we explore dates from December 18, 2000 up to and including September 8, 2019. Using a numerical criterion, we characterize the typical and extreme behavior of the concentrated NHS emissions across the catalog. The mean power of the NHS is found to be 1.91 GW with a maximum brightness of 2.02 Rayleighs (R), representing by far the brightest parts of the jovian X‐ray spectrum. We report a statistically significant region of emissions at the NHS center which is always present, the averaged hot spot nucleus (AHSNuc), with mean power of 0.57 GW and inferred average brightness of 1.2 R. We use a flux equivalence mapping model to link this distinct region of X‐ray output to a likely source location and find that the majority of mappable NHS photons emanate from the pre‐dusk to pre‐midnight sector, coincident with the dusk flank boundary. A smaller cluster maps to the noon magnetopause boundary, dominated by the AHSNuc, suggesting that there may be multiple drivers of X‐ray emissions. On application of timing analysis techniques (Rayleigh, Monte Carlo, Jackknife), we identify several instances of statistically significant quasi‐periodic oscillations (QPOs) in the NHS photons ranging from 2.3 to 36.4 min, suggesting possible links with ultra‐low frequency activity on the magnetopause boundary (e.g., dayside reconnection, Kelvin‐Helmholtz instabilities).
Highlights
Jupiter has strong auroral X-ray emissions which are observed to be concentrated into a “hot spot”
Table of Chandra ObsID, hot spot interval and results of the Jackknife test performed on statistically significant quasi-periodic oscillations (QPOs) found in the northern hot spot (NHS)
From the ever expanding catalogue of Chandra HRC-I observations of jovian Xrays across multiple solar cycles and various solar wind and magnetospheric conditions, we present the first statistical study of its kind to analyze typical and extreme “hot spot”
Summary
Jupiter has strong auroral X-ray emissions which are observed to be concentrated into a “hot spot”. The first spatially resolved X-ray auroral “hot spot” was observed by Chandra ∼ 20 years ago, discovered by Gladstone et al (2002) in the northern polar region. Gladstone et al (2002) defined the hot spot region as a 5◦ radius circle centered on 170◦ System III (S3) longitude and 65◦ latitude. Timing analysis of the 113 photons within the hot spot showed a flaring of X-ray emissions or quasi-periodic oscillation (QPO) at ∼ 45 min, similar to pulsations found in the radio emission from the Ulysses flyby (MacDowall et al, 1993) and electron bursts from the Cassini flyby (Krimigis et al, 2002)
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