Intense Magnetopause Deformation Induced by an Extreme HFA Event: 3-D Hybrid Simulations and Soft X-Ray Imaging

The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a joint mission of the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). Its primary objective is to investigate the Earth's magnetosphere's dynamic response to solar wind (SW) impacts through simultaneous in situ measurements of magnetosheath plasma and magnetic fields, X-ray imaging of the magnetosheath and magnetic cusps, and UV imaging of global auroral distributions. In this study, extremely magnetopause deformations associated with Hot Flow Anomalies (HFAs) are examined using a three-dimensional (3-D) global hybrid simulation. Nonuniform grids are used to enhance the resolution of the magnetosheath. Considering the parameters of SMILE's Soft X-ray Imager, we analyze the integrated soft X-ray intensity along the line-of-sight (LOS) over durations ranging from less than one minute to approximately five minutes. The simulation results demonstrate that: (1) high-speed jets (HSJs) at the leading and trailing edges of the HFA can generate X-ray intensities an order of magnitude stronger than the background magnetosheath, whereas the core region of the HFA corresponds to an X-ray dimming area; (2) a mature HFA can cause the magnetopause to expand outward by several Earth radii, exposing magnetospheric material to the solar wind ahead of the bow shock; (3) in minute-scale integrations, the HFA structure, moving from the northern to the southern hemisphere, can be discerned in the integral images within a duration of less than five minutes, while integrations lasting five minutes or longer smooth out the signal entirely. This study serves as a pre-study for the SMILE mission.