Abstract
AbstractAn MHD‐based model of terrestrial solar wind charge exchange (SWCX) is created and compared to 19 case study observations in the 0.5–0.7 keV emission band taken from the European Photon Imaging Cameras on board XMM‐Newton. This model incorporates the Global Unified Magnetosphere‐Ionosphere Coupling Simulation‐4 MHD code and produces an X‐ray emission datacube from O7+ and O8+ emission lines around the Earth using in situ solar wind parameters as the model input. This study details the modeling process and shows that fixing the oxygen abundances to a constant value reduces the variance when comparing to the observations, at the cost of a small accuracy decrease in some cases. Using the ACE oxygen data returns a wide ranging accuracy, providing excellent correlation in a few cases and poor/anticorrelation in others. The sources of error for any user wishing to simulate terrestrial SWCX using an MHD model are described here and include mask position, hydrogen to oxygen ratio in the solar wind, and charge state abundances. A dawn‐dusk asymmetry is also found, similar to the results of empirical modeling. Using constant oxygen parameters, magnitudes approximately double that of the observed count rates are returned. A high accuracy is determined between the model and observations when comparing the count rate difference between enhanced SWCX and quiescent periods.
Highlights
The terrestrial solar wind charge exchange process involves the liberation and capture of an electron from a neutral species at the Earth to a heavy, high charge state, ion in the solar wind
An initial investigation of the 30 case studies showed that the European Photon Imaging Camera (EPIC) camera suffered from sparse data in six cases, which were removed from the study
In this study we have taken the data from 19 case studies using the EPIC-metal-oxide semiconductor (MOS) instruments on XMM-Newton to examine the accuracy of MHD modeling when describing solar wind charge exchange from the Earth’s magnetosheath
Summary
The terrestrial solar wind charge exchange process involves the liberation and capture of an electron from a neutral species at the Earth (i.e., hydrogen) to a heavy, high charge state, ion in the solar wind. More recent attempts at quantifying charge exchange from other ions with emission lines around the 1 keV band have been performed, though the lack of cross-sectional information for a number of faint transition lines causes a high uncertainty in the results [Kuntz et al, 2015]. This previous research showed a stronger correlation of the 1 keV band ROSAT fluxes with solar wind flux than the 3 keV band. The spectral parameters will vary according to sky position; the ROSAT to EPIC conversion in these bands is not very sensitive to plausible variations in the parameters, and the resultant uncertainty is comparable to the uncertainty due to the intercalibration between the instruments
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