Characteristics of Jupiter's X‐Ray Auroral Hot Spot Emissions Using Chandra

• Published in: Journal of geophysical research. Space physics 2021-09, Vol.126 (9), p.n/a
• Main Authors: Weigt, D. M., Jackman, C. M., Vogt, M. F., Manners, H., Dunn, W. R., Gladstone, G. R., Kraft, R., Branduardi‐Raymont, G., Louis, C. K., McEntee, S. C.
• Format: Article
• Language: English
• Subjects: aurora; Auroral emissions; Auroras; Brightness; Emissions; Hot spots (geology); jovian magnetosphere; Jupiter; Jupiter atmosphere; Magnetic fields; Magnetopause; magnetosphere; Mapping; Mean; Morphology; Photons; Planetary magnetic fields; Solar system; Solar wind; Solar wind effects; Space telescopes; Telescopes; ULF waves; Wind effects; X‐ray aurora
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2021JA029243

To 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). Plain Language Summary The auroral emissions (northern and southern lights) on Jupiter are the most powerful in our Solar System and have been observed across the electromagnetic spectrum. The cause, or driver, of Jupiter's auroras is still an open question with lots of scientific debate. The solar wind can have an effect, as can Jupiter's volcanic moon Io. The plasma and magnetic field interactions can produce auroras on Jupiter in the X‐ray waveband. These powerful X‐ray emissions can be observed by telescopes like the Chandra X‐ray Observatory (CXO) that orbit Earth. The X‐ray data we analyze here have been found to flash or pulsate at certain periods, spanning the ∼20 years Chandra has observed Jupiter. We use mapping and timing analysis techniques to analyze the entire catalog from the high‐resolution camera on‐board Chandra. We report significant auroral X‐ray regions and pulsations in the No