Comparing Jupiter's equatorial X-ray emissions with solar X-ray flux
over 19 years of the Chandra mission
Abstract
We present a statistical study of Jupiter’s disk X-ray emissions using
19 years of Chandra X-Ray Observatory (CXO) observations. Previous work
has suggested that these emissions are consistent with solar X-rays
elastically scattered from Jupiter’s upper atmosphere. We showcase a new
Pulse Invariant (PI) filtering method that minimises instrumental
effects which may produce unphysical trends in photon counts across the
nearly-two-decade span of the observations. We compare the CXO results
with solar X-ray flux data from the Geostationary Operational
Environmental Satellites (GOES) X-ray Sensor (XRS) for the wavelength
band 1-8 Å (long channel), to quantify the correlation between solar
activity and jovian disk counts. We find a statistically significant
Pearson’s Correlation Coefficient (PCC) of 0.9, which confirms that
emitted jovian disk X-rays are predominantly governed by solar activity.
We also utilise the high spatial resolution of the High Resolution
Camera Instrument (HRC-I) on board the CXO to map the disk photons to
their positions on Jupiter’s surface. Voronoi tessellation diagrams were
constructed with the JRM09 (Juno Reference Model through Perijove 9)
internal field model overlaid to identify any spatial preference of
equatorial photons. After accounting for area and scattering across the
curved surface of the planet, we find a preference of jovian disk
emission at 2-3.5 Gauss surface magnetic field strength. This suggests
that a portion of the disk X-rays may be linked to processes other than
solar scattering: the spatial preference associated with magnetic field
strength may imply increased precipitation from the radiation belts, as
previously postulated.