Solar wind charge exchange X-ray emission from Mars Model and data comparison

摘要

Aims. We study the soft X-ray emission induced by charge exchange (CX)collisions between solar-wind, highly charged ions and neutral atoms of theMartian exosphere. Methods. A 3D multi species hybrid simulation model withimproved spatial resolution (130 km) is used to describe the interactionbetween the solar wind and the Martian neutrals. We calculated velocity anddensity distributions of the solar wind plasma in the Martian environment withrealistic planetary ions description, using spherically symmetric exospheric Hand O profiles. Following that, a 3D test-particle model was developed tocompute the X-ray emission produced by CX collisions between neutrals and solarwind minor ions. The model results are compared to XMM-Newton observations ofMars. Results. We calculate projected X-ray emission maps for the XMM-Newtonobserving conditions and demonstrate how the X-ray emission reflects theMartian electromagnetic structure in accordance with the observed X-ray images.Our maps confirm that X-ray images are a powerful tool for the study of solarwind - planetary interfaces. However, the simulation results reveal severalquantitative discrepancies compared to the observations. Typical solar wind andneutral coronae conditions corresponding to the 2003 observation period of Marscannot reproduce the high luminosity or the corresponding very extended haloobserved with XMM-Newton. Potential explanations of these discrepancies arediscussed.