ROSAT and XMM-Newton observations of solar wind charge exchange with neutral atoms

M.R. Collier (1), S.L. Snowden (2), T.E. Moore (1), K.D. Kuntz (3)

(1) NASA/GSFC, Code 692, Greenbelt, Maryland 20771
(2) NASA/GSFC, Code 662, Greenbelt, Maryland 20771
(3) Astronomy Department, UMBC, Baltimore, Maryland


High charge state solar wind ions charge exchanging with neutral gas create soft
Xrays, a phenomenon first observed as X-ray emission from comets. Here, we present
two examples of how the X-ray products of these charge exchange reactions may be
used to probe the near Earth distribution of neutral gas. The first is a series of
four XMM-Newton observations of the Hubble Deep Field North. The initial three
exposures were statistically consistent with each other while the fourth, which
coincided with a significant increase in the solar wind flux, showed a strong
enhancement at energies less than 1.4 keV, which was dominated by line emission.
Data from the Low Energy Neutral Atom imager on the IMAGE spacecraft inside the
EarthÕs magnetosphere during this event show Sun signal brightening indicating
enhanced solar wind charge exchange was occurring at this time. The second is the
long-term trending of the ROSAT All-Sky Survey data which shows an enhancement in
early December consistent with where the downstream helium focusing cone is
expected. However, the distribution is shifted toward higher ecliptic longitudes
than the expected downstream direction and appears to exhibit a two-peak
structure.

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Presented at the 35th COSPAR Scientific Assembly, Paris, France, July 18-25, 2004.