The Solar Wind Charge-Exchange Production Factor for Hydrogen

Abstract

The production factor, or broad band averaged cross-section, for solar wind charge-exchange with hydrogen producing emission in the ROSAT 1/4 keV (R12) band is $3.8\pm 0.2\times 10^{-20}$ count degree${}^{-2}$ cm${}^4$. This value is derived from a comparison of the Long-Term (background) Enhancements in the ROSAT All-Sky Survey with magnetohysdrodynamic simulations of the magnetosheath. This value is 1.8 to 4.5 times higher than values derived from limited atomic data, suggesting that those values may be missing a large number of faint lines. This production factor is important for deriving the exact amount of 1/4 keV band flux that is due to the Local Hot Bubble, for planning future observations in the 1/4 keV band, and for evaluating proposals for remote sensing of the magnetosheath. The same method cannot be applied to the 3/4 keV band as that band, being composed primarily of the oxygen lines, is far more sensitive to the detailed abundances and ionization balance in the solar wind. We also show, incidentally, that recent efforts to correlate XMM-Newton observing geometry with magnetosheath solar wind charge-exchange emission in the oxygen lines have been, quite literally, misguided. Simulations of the inner heliosphere show that broader efforts to correlate heliospheric solar wind charge-exchange with local solar wind parameters are unlikely to produce useful results.

arXiv comment19 pages, 16 figures, submitted to ApJ

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Cited by in corpus (7)

• The Structure of the Local Hot Bubble
• Solar Wind Charge Exchange: An Astrophysical Nuisance
• Solar Wind Charge Exchange contribution to the ROSAT All Sky Survey Maps
• The Solar-Cycle Temporal Variation of the Solar Wind Charge Exchange X-ray Lines
• Soft X-ray imaging of Earth's dayside magnetosheath and cusps using hybrid simulations
• Soft X-Ray Imaging of Magnetopause Reconnection Outflows Under Low Plasma-$\beta$ Solar Wind Conditions
• Modeling of geocoronal solar wind charge exchange events detected with Suzaku