Soft X‐ray Imaging of the Magnetosheath and Cusps Under Different Solar Wind Conditions: MHD Simulations

T R Sun,R E Lopez,S F Sembay,C P Escoubet,Y H Guo,G Branduardi‐Raymont,Z Q Liu,F Wei,C Wang,X Z Yu,X C Guo,J H Zheng,L Dai

doi:10.1029/2018ja026093

Abstract

AbstractThe soft X‐ray emissions from the Earth's magnetosheath and cusp regions are simulated under different solar wind conditions, based on the PPMLR‐MHD code. The X‐ray images observed by a hypothetical telescope are presented, and the basic responses of the magnetopause and cusp regions are discernable in these images. From certain viewing geometries, the magnetopause position in the equatorial plane, as well as the latitudinal scales and azimuthal extent of cusp can be directly extracted from the X‐ray images. With these reconstructed positions, the issues we are able to analyze include but are not limited to the compression of magnetopause and widening of the cusp after an enhancement of solar wind flux, as well as the erosion of the magnetopause and equatorward motion of cusp after the southward turning of the interplanetary magnetic field. Hence, the X‐ray imaging is an appropriate technique to study the large‐scale motion of magnetopause and cusps in response to solar wind variations.

Highlights

The Earth's magnetopause is formed as a result of the interaction between the solar wind and the terrestrial magnetic field
PX near the subsolar magnetopause is enhanced with an increasing solar wind number density, and the reasons for this enhancement are as follows: (1) increased number density in the solar wind, (2) increased thermal pressure in the magnetosheath caused by a stronger bow shock, and (3) larger neutral density as the magnetopause is closer to the Earth
Wave-like structures are seen at the flank magnetopause in Figure 4a1, which are related to the development of Kelvin-Helmholtz instabilitsy (KHI)

Summary

Introduction

The Earth's magnetopause is formed as a result of the interaction between the solar wind and the terrestrial magnetic field. It is difficult to extract information about the magnetopause position from the current data In this context, the ESA-CAS joint mission, Solar wind-Magnetosphere-Ionosphere Link Explorer (SMILE), is proposed to achieve the objective of remotely detecting the large-scale magnetopause boundary (Branduardi-Raymont et al, 2016; Wang et al, 2017). The ESA-CAS joint mission, Solar wind-Magnetosphere-Ionosphere Link Explorer (SMILE), is proposed to achieve the objective of remotely detecting the large-scale magnetopause boundary (Branduardi-Raymont et al, 2016; Wang et al, 2017) It will have a Soft X-ray Imager (SXI) onboard, with a large FOV: 16◦ × 27◦.

X-ray Intensity

Simulation Results

Discussion and Conclusion