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In this study we analyse a 40 hour (~ 4 jovian rotation) Chandra X-ray observation beginning on 15 September 2021 in order to study the morphology and time variability of the auroral X-ray emissions at Jupiter. At the time of this observation, Juno's orbit had taken the spacecraft into the dusk magnetosphere of Jupiter, thought to be the most likely source region for driving of jovian auroral X-rays. One leading theory for the driver of these emissions is Ultra Low Frequency (ULF) waves propagating along jovian magnetic field lines which can be initiated by processes on the dusk flank of the magnetosphere. This was the first time that this region had been observed by an orbiter since Galileo > 20 years ago, and never before has there been contemporaneous in situ and X-ray observations here. The long exposure time of this observation enables monitoring of the auroral regions over multiple jovian rotations, which is key to understand how variable the X-ray emissions can be. This allows for the identification of short timescale changes in the magnetospheric dynamics. Wavelet transforms and Rayleigh testing are used to search for statistically significant quasi-periodic pulsations of the X-ray emissions in the dataset. We combine the remote X-ray analysis with examination of data from the Juno Waves instrument, which has already shown that quasi-periodic emissions in the radio waveband can change on timescales of a few hours. Furthermore, we incorporate data from the Juno MAG instrument to provide magnetospheric context over the duration of the Chandra X-ray observation, and identify a possible compression event in the second half of the 40 hour time window. The Tao et al. (2005) solar wind propagation model also suggests a disturbed/compressed magnetosphere at this time, which is further supported by comparing the measured magnetic field against the baseline Kivelson and Khurana (2002) lobe magnetic field model.

During its 53-day polar orbit around Jupiter, Juno often crosses the boundaries of the Jovian magnetosphere, namely the magnetopause and bow shock, as well as the plasma disc (located at the centrifugal equator). The positions of the magnetopause and bow shock allow us to determine the dynamic pressure of the solar wind (using both the updated model of Joy et al. 2002 by Ranquist et al., 2020 and/or in situ data) which allows us to infer magnetospheric compression or relaxation, while the observations of plasma disc perturbations allows us to infer magnetospheric reconfigurations.The aim of this study is to examine Jovian radio emissions during magnetospheric perturbations. We then use our analysis to determine the relationship between the solar wind and Jovian radio emissions (observed and emitted from different regions of the magnetosphere, from different mechanisms, and at different wavelengths from kilometers to decameters).In this presentation, we show case studies for each typical case (bow shock, magnetopause and plasma disk crossings) and show that the activation of new radio sources is related to magnetospheric disturbances. By performing a statistical study of these crossings, we show the relationship between the activation of new radio sources (emission intensity and extension, source positions) and the solar wind (dynamic pressure, magnetic intensity, …). The final aim is to be able to use observations of planetary radio emission as a proxy for the solar wind conditions.

During its 53-day polar orbit around Jupiter, Juno often crosses the boundaries of the Jovian magnetosphere, namely the magnetopause and bow shock, as well as the plasma disc (located at the centrifugal equator). The positions of the magnetopause and bow shock allow us to determine the dynamic pressure of the solar wind (using both the updated model of Joy et al. 2002 by Ranquist et al., 2020 and/or in situ data) which allows us to infer magnetospheric compression or relaxation, while the observations of plasma disc perturbations allows us to infer magnetospheric reconfigurations. The aim of this study is to examine Jovian radio emissions during magnetospheric perturbations. We then use our analysis to determine the relationship between the solar wind and Jovian radio emissions (observed and emitted from different regions of the magnetosphere, from different mechanisms, and at different wavelengths from kilometers to decameters). In this presentation, we show case studies for each typical case (bow shock, magnetopause and plasma disk crossings) and show that the activation of new radio sources is related to magnetospheric disturbances. By performing a statistical study of these crossings, we hope to be able to show the relationship between the activation of new radio sources (emission intensity and extension, source positions) and the solar wind (dynamic pressure, magnetic intensity, ...), with the aim of being able to use observations of planetary radio emission as a proxy for the solar wind.

Every 19 years, Saturn passes through Jupiter's 'flapping' magnetotail. Here, we report Chandra X-ray observations of Saturn planned to coincide with this rare planetary alignment and to analyse Saturn's magnetospheric response when transitioning to this unique parameter space. We analyse three Director's Discretionary Time (DDT) observations from the High Resolution Camera (HRC-I) on-board Chandra, taken on November 19, 21 and 23 2020 with the aim to find auroral and/or disk emissions. We infer the conditions in the kronian system by looking at coincident soft X-ray solar flux data from the Geostationary Operational Environmental Satellite (GOES) and Hubble Space Telescope (HST) observations of Saturn's ultraviolet (UV) auroral emissions. The large Saturn-Sun-Earth angle during this time would mean that most flares from the Earth-facing side of the Sun would not have impacted Saturn. We find no significant detection of Saturn's disk or auroral emissions in any of our observations. We calculate the 3$\sigma$ upper band energy flux of Saturn during this time to be 0.9 - 3.04 $\times$ 10$^{14}$ erg cm$^{-2}$ s$^{-1}$ which agrees with fluxes found from previous modelled spectra of the disk emissions. We conclude by discussing the implications of this non-detection and how it is imperative that the next fleet of X-ray telescope (such as Athena and the Lynx mission concept) continue to observe Saturn with their improved spatial and spectral resolution and very enhanced sensitivity to help us finally solve the mysteries behind Saturn's apparently elusive X-ray aurora., Comment: 8 pages, 3 figures, accepted for publication in MNRAS

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 (Formula presented.) 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 (Formula presented.) 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).

In 1979, the Voyager spacecraft arrived at Jupiter. Amongst their rich array of discoveries, they identified bright bursts of radio emission at kHz frequencies1, often called quasi-periodic (QP) bursts, and discovered Jupiter’s ultraviolet (UV) aurora2 - the most powerful aurora in the Solar System3. The same year that the Voyager spacecraft explored the Jovian system, the Einstein X-ray Observatory took the first X-ray images of Jupiter4 and discovered that planets can also produce bright and dynamic X-ray aurora5,6. Over the subsequent decades, these distinct multi-waveband emissions have all been observed to pulse with quasi-periodic regularity7–10. Here, we combine simultaneous observations by the Juno spacecraft with the X-ray and UV observatories: XMM-Newton, Chandra and the Hubble Space Telescope. These observations show that the radio, UV and X-ray pulses are all synchronised, beating in time together. Further, they reveal that the X-ray and radio pulses share an identical 42.5 minute periodicity with simultaneously measured compression-mode Ultra Low Frequency (ULF) waves in Jupiter’s outer magnetosphere11. ULF waves are known to modulate wave-particle interactions that can cause electron and ion precipitation, providing a physically consistent explanation for the observed simultaneous ion and electron emissions. The unification of Jupiter’s X-ray, UV and radio pulsations and their connection to ULF waves provides fundamental and potentially universal insights into the redistribution of energy in magnetised space environments.

We present an extensive statistical study of all 29 Chandra High Resolution Camera (HRC-I) observations, covering ∼ 20 years worth of data from 18th December 2000 to 8th September 2019. Eight of these observations were pre-Juno and 21 while Juno was exploring the Jovian system providing in situ context. The first spatially resolved X-ray auroral "hot spot" was discovered by Gladstone et al. (2002) from Chandra observations of Jupiter’s North Pole. The emissions observed were found to pulsate with a 45-min quasi-periodic oscillation (QPO) and believed to originate in the outer magnetosphere (> 30 RJ) [1]. Since then, from using subsequent remote sensing X-ray observations in tandem with available in situ data, we know that the emissions from the hot spot consist of soft X-rays (SXRs, photons with energy < 2 keV) from charge exchange processes between precipitating ions and neutrals within the Jovian atmosphere [2]. However, the hot spot is found to be very variable both spatially and temporally [3] in all observations to date, thus proving determining the driver to be very difficult. In this study, we characterise the typical and extreme behaviour of the hot spot emissions across the entire catalogue for the first time. Examining both types of behaviour allows us to determine the full extent of hot spot variability. We mainly focus on the northern hot spot (NHS) as: (1) the viewing geometry over the catalogue favours the North Pole best and (2) the NHS has been shown to be mostly non-conjugate with the south [4, 5], producing much stronger emission. We present heat maps and 2-D histograms to show the overall average hot spot morphology. The hot spot was defined using a numerical criterion of location and photon concentration (S3 longitude: 100° - 240°; latitude: 40° - 90°; concentration: > 7 photons per 5° S3 lon × 5° lat) [6]. From the catalogue, 26 out of 29 observations had emission within this threshold. Using a 2-D histogram with 3° S3 lon × 3° lat binning, we find a significant region of concentrated NHS emission at ∼ 162° - 171° S3 longitude and 60° - 66° latitude, herein referred to as the averaged hot spot nucleus (AHSNuc). The AHSNuc is found to mainly map to the noon magnetopause boundary while most events from the NHS are found to originate on the dusk-midnight boundary. This suggests that multiple drivers may produce the NHS. The mapping is carried out using a flux equivalence model [7, 8] with the Grodent Anomaly Model (GAM) [9], to model the internal field. We discuss the uncertainty in our mapping associated with possible fluctuations in ionospheric position and mapping limitations to improve the accuracy of our interpretations. Finally, we apply the Rayleigh test technique discussed in Jackman et al. (2018) to find any significant QPOs within the hot spot and the AHSNuc.We create a catalogue of all our timing analysis results noting all the significant QPOs found and test their robustness using a Jackknife test. We interpret the NHS and AHSNuc locations and compare the timescales of the QPOs to known possible drivers (such as magnetopause reconnection [10] and ultralow frequency (ULF) waves [11]) in an attempt to determine the overall hot spot driver/drivers. References[1] Gladstone, R.G.; Waite, J.; Grodent, D. et al.: A pulsating auroral X-ray hot spot on Jupiter, Nature, Vol. 415, pp. 1000-1002, 2002. [2] Branduardi-Raymont, G., Elsner, R. F., Galand, M. et al.: Spectral morphology of the X-ray emission from Jupiter’s aurorae, Journal of Geophysical Research: Space Physics, Vol. 113, pp. 1-11, 2008. [3] Jackman, C. M., Knigge, C., Altamirano, D. et al.: Assessing Quasi-Periodicities in Jovian X-Ray Emissions: Techniques and Heritage Survey, Journal of Geophysical Research: Space Physics, Vol. 123, pp. 9204-9221, 2018. [4] Dunn,W. R., Branduardi-Raymont, G., Ray, L. C. et al.: The independent pulsations of Jupiter’s northern and southern X-ray auroras, Nature Astronomy, Vol. 1, pp 758-764, 2017. [5] Wibisono A. D., Branduardi-Raymont, G., Dunn, W. R. et al.: Temporal and Spectral Studies by XMM-Newton of Jupiter's X-ray Auroras During a Compression Event, Journal of Geophysical Research: Space Physics, Vol. 125, e2019JA027676, 2020. [6] Weigt, D. M., Jackman, C. M., Dunn, W. R. et al.: Chandra Observations of Jupiter’s X-ray Auroral Emission During Juno Apojove 2017, Journal of Geophysical Research: Planets, Vol. 125, e2019JE006262, 2020. [7] Vogt, M. F., Kivelson, M. G., Khurana, K. K. et al.: Improved mapping of Jupiter’s auroral features to magnetospheric sources, Journal of Geophysical Research: Space Physics, Vol. 116, A03220, 2011. [8] Vogt, M. F., Bunce, E. J., Kivelson, M. G. et al.: Magnetosphere-ionosphere mapping at Jupiter: Quantifying the effects of using different internalfield models, Journal of Geophysical Research: Space Physics, Vol. 120, pp. 2584–2599, 2015. [9] Grodent, D., Bonfond, B., Gérard, J. C. et al.: Auroral evidence of a localized magnetic anomaly in Jupiter’s northern hemisphere, Journal of Geophysical Research: Space Physics, Vol. 113, pp. 1-10, 2008. [10] Ebert, R.W., Allegrini, F., Bagenal, F. et al.: Accelerated flows at Jupiter’s magnetopause: Evidence for magnetic reconnection along the dawn flank. Geophysical Research Letters, Vol. 44, pp. 4401–4409, 2017. [11] Manners, H., Masters, A., and Yates, J.N.: Standing Alfvén waves in Jupiter’s magnetosphere as a source of ∼ 10- to 60-min quasiperiodic pulsations, Geophysical Research Letters, Vol. 45, pp. 8746–8754, 2018.

Jupiter's auroral X-rays have been observed for 40 years with an unknown driver producing quasiperiodic emission, concentrated into auroral hot spots. In this study we analyze an (Formula presented.) 10-hr Chandra observation from 18:56 on 18 June 2017. We use a new Python pipeline to analyze the auroral morphology, perform timing analysis by incorporating Rayleigh testing, and use in situ Juno observations to infer the magnetosphere that was compressed during the Chandra interval. During this time Juno was near its apojove position of (Formula presented.) 112 (Formula presented.), on the dawn flank of the magnetosphere near the nominal magnetopause position. We present new dynamical polar plots showing an extended X-ray hot spot in the northern auroral region traversing across the Jovian disk. From this morphology, we propose setting a numerical threshold of (Formula presented.) 7 photons per 5° System III longitude (Formula presented.) 5° latitude to define a photon concentration of the northern hot spot region. Our timing analysis finds two significant quasiperiodic oscillations (QPOs) of (Formula presented.) 37 and (Formula presented.) 26 min within the extended northern hot spot. No statistically significant QPOs were found in the southern X-ray auroral emission. The Rayleigh test is combined with Monte Carlo simulation to find the statistical significance of any QPOs found. We use a flux equivalence mapping model to trace the possible origin of the QPOs, and thus the driver, to the dayside magnetopause boundary.