Dynamical Response of Solar Wind Charge Exchange Soft X-Ray Emission in Earth's Magnetosphere to the Solar Wind Proton Flux

Yingjie Zhang (1, 2) , Tianran Sun (1) , Jennifer A Carter (3) , Steve Sembay (3) , Dimitra Koutroumpa (4) , Ji Li (5) , Wenhao Liu (5) , Chi Wang (1, 2)

1 SKSW - State Key Laboratory of Space Weather [Beijing]
2 College of Earth and Planetary Sciences [Beijing]
3 School of Physics and Astronomy [Leicester]
4 HELIOS - LATMOS
5 Purple Mountain Observatory

This work studies the dynamic response of solar wind charge exchange (SWCX) soft X-ray emission in the Earth's magnetosphere to the solar wind proton flux. Unlike previous studies that attempted to use complex magnetohydrodynamic models to match the details of observed SWCX of a necessarily limited number of cases, this work focuses on determining the changes over individual observations in a much larger sample. To provide the cleanest test, we selected XMM-Newton observations when the solar wind proton flux changed suddenly by a factor greater than 1.5 and calculated the correlation coefficient between the SWCX emission in the 0.5-0.7 keV band and the proton flux. We find that the dynamical response is weak when the solar wind proton flux is low (<10,000 n * km/cc/s) because its variation is smaller than the uncertainty due to other emission components, but this response increases with the proton flux and its change value. The response is improved when the valence state of solar wind ions is high, as a higher abundance of ions generating SWCX can produce a greater correlation even though the proton flux is relatively low. It is conducive to the study of interplanetary coronal mass ejections (ICMEs) because ions in ICMEs are usually highly ionized. For XMM-Newton, the 0.5-0.7 keV band shows the strongest correlation, as the instrumental response decreases at lower energies and the SWCX emission decreases at higher energies. Moreover, the closer the satellite line of sight is to the subsolar magnetopause with the strongest SWCX emissivity, the better the correlation. Unified Astronomy Thesaurus concepts: X-ray astronomy (1810); Diffuse x-ray background (384); Solar coronal mass ejections (310); Solar wind (1534); Solar-terrestrial interactions (1473)

Mots clés: X-ray astronomy; Diffuse x-ray background; Solar coronal mass ejections; Solar wind; Solar-terrestrial interactions

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]

Yingjie Zhang, Tianran Sun, Jennifer A Carter, Steve Sembay, Dimitra Koutroumpa, et al.. Dynamical Response of Solar Wind Charge Exchange Soft X-Ray Emission in Earth's Magnetosphere to the Solar Wind Proton Flux. The Astrophysical Journal, 2023, 948, pp.69. ⟨10.3847/1538-4357/acc326⟩. ⟨insu-04091450⟩