Modeling of geocoronal solar wind charge exchange events detected with Suzaku

TL;DR

This study developed a model to predict geocoronal SWCX X-ray emissions detected by Suzaku, successfully matching observed intensities and variations by integrating solar wind data, magnetospheric models, and neutral hydrogen distributions.

Contribution

The paper presents a comprehensive model combining multiple data sources to accurately simulate and interpret geocoronal SWCX X-ray emissions observed with Suzaku.

Findings

Modeled O VII intensities matched observations within a factor of three in most cases.

Modeled O VIII intensities were underestimated, indicating areas for model improvement.

Light curves of SWCX emissions were successfully reproduced, including short-term variations.

Abstract

A model of geocoronal solar wind charge exchange (SWCX) emission was built and compared to five Suzaku detections of bright geocoronal SWCX events. An exospheric neutral hydrogen distribution model, charge exchange cross sections, solar wind ion data taken with the ACE and WIND satellites, and magnetic field models of the Earth's magnetosphere are all combined in order to predict time-variable geocoronal SWCX emission depending on line-of-sight directions of the Suzaku satellite. The modeled average intensities of O VII emission lines were consistent with the observed ones within a factor of three in four out of the five cases except for an event in which a line-of-sight direction was toward the night side of the high-latitude magnetosheath and a major geomagnetic storm was observed. Those of O VIII emission lines were underestimated by a factor of three or more in all the five cases. On the other hand, the modeled O VII and O VIII light curves reproduced the observed ones after being scaled by ratios between the observed and modeled average intensities. In particular, short-term variations due to line-of-sight directions traversing cusp regions during an orbital motion of the Suzaku satellite were reproduced. These results are discussed in the context of model uncertainties.