XMM-牛顿线发射分析程序（X-LEAP）III：22年XMM-牛顿观测揭示的地球磁层X射线发射
The XMM-Newton Line Emission Analysis Program (X-LEAP) III: Earth's Magnetospheric X-ray Emission Revealed by 22-Year XMM-Newton Observations
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中文总结 AI 辅助
研究利用XMM-牛顿观测，通过提取磁层太阳风电荷交换的O VII线发射数据，分析其方向依赖性并建模磁鞘结构，得出经验O VII发射效率，揭示了地球磁层X射线发射情况。
中文摘要 AI 辅助
磁层保护地球免受强烈太阳活动影响，其结构在观测中仍不确定。本研究绘制了磁层中的X射线发射图，该发射由高电离太阳风与地球周围中性气体的电荷交换引起，即磁层太阳风电荷交换（SWCX）。特别地，从XMM线发射分析程序（X-LEAP）采用的O VII线发射数据中提取磁层SWCX。观测到的磁层SWCX显示朝向太阳的发射增强，约为$I_{\rm OVII}^{\rm mag}\approx 2$光子$\rm cm^{-2}~ s^{-1}~sr^{-1}$，与数值模拟预测形状一致。此外，磁层SWCX对XMM指向方向有依赖性，基于此首次用软X射线观测对三维磁鞘结构建模，约束22年平均边界几何形状和SWCX发射率分布。最后利用XMM数据得出经验O VII发射效率为$\alpha_{\rm OVII}=(2.1\pm0.4) \times 10^{-16}\ {\rm eV\,cm^{2}}$。
英文摘要
The magnetosphere, protecting the Earth from intense solar activity, is also shaped by the solar wind, while its structure is still uncertain in observation. In this study, we map the X-ray emission in the magnetosphere, which is induced by the charge exchange between the highly-ionized solar wind and the neutral gas around the Earth, known as the magnetospheric solar wind charge exchange (SWCX). In particular, we extract the magnetospheric SWCX in the O VII line emission data adopted from the XMM Line Emission Analysis Program (X-LEAP). The observed magnetospheric SWCX shows an enhanced emission of approximately $I_{\rm OVII}^{\rm mag}\approx 2$ photons $\rm cm^{-2}~ s^{-1}~sr^{-1}$ toward the Sun, showing a consistent shape predicted by numerical simulations. Furthermore, this magnetospheric SWCX exhibits a dependence on the XMM pointing direction, which traces the path length of SWCX emission in the Earth's magnetosphere. Building on this directional dependence, we model the 3D magnetosheath structure using soft X-ray observations for the first time, constraining the averaged boundary geometry and SWCX emissivity distribution over 22 years. Finally, utilizing the XMM data, we derive an empirical O VII emission efficiency of $α_{\rm OVII}=(2.1\pm0.4) \times 10^{-16}\ {\rm eV\,cm^{2}}$.
