Time Variability of the Geocoronal Solar-Wind Charge Exchange in the Direction of the Celestial Equator
Abstract
We report on the detection of a time variable OVII line emission in a deep 100 ks Suzaku X-ray Imaging Spectrometer spectrum of the galactic ridge X-ray emission. The observed line intensity is too strong (11 ± 2 line unit or photon cm-2 s-1 sr-1) to be emitted inside the heavily obscured galactic disk. It showed a factor of two time variation that showed a significant (∼4σ) correlation with the solar-wind O7+ ion flux. The high line intensity and good time correlation with the solar wind strongly suggests that it originated from geocoronal solar-wind charge-exchange emission. We discuss the X-ray line intensity while considering a line-of-sight direction and also theoretical distribution models of the neutral hydrogen and solar wind around Earth. Our results indicate that X-ray observations of geocoronal solar-wind charge-exchange emission can be used to constrain these models.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- August 2010
- DOI:
- 10.1093/pasj/62.4.981
- Bibcode:
- 2010PASJ...62..981E
- Keywords:
-
- Earth;
- Sun: solar-terrestrial relations;
- Sun: solar wind;
- X-rays: diffuse background