A Theoretical Study of the Tomographic Reconstruction of Magnetosheath
X-ray Emissions
Abstract
We present an initial assessment of using tomography on
single-spacecraft images to reconstruct 3D X-ray emissions from the
Earth’s magnetosheath. 3D structures in the Earth’s magnetosphere have
been studied using superposed epoch techniques with single-point
single-spacecraft observations. They have yielded great insights, but
some studies are observation starved, particularly for infrequent solar
wind conditions. Global imaging data have provided more insight about
these structures, but are 2D projections of 3D structures. We explore
the use of tomographic reconstruction techniques to understand what can
be extracted from global images from a single spacecraft. The Solar wind
Magnetosphere Ionosphere Link Explorer (SMILE) mission, due to launch in
2024 on a 3-year mission, will carry a soft X-ray imager which will
capture emissions from portions of the magnetosheath and upstream solar
wind. We already demonstrated that the 3D shape of the magnetopause and
the bow shock can be extracted from such images with suitable
assumptions. The next step is to examine whether full 3D reconstructions
of the emissions are possible. We explore the limited range of viewing
angles, which affect the accuracy of the reconstructions and introduce
artifacts in some cases, and the low count-rates in the images which
introduce noise in the reconstructions which must be filtered out.
Despite these limitations we show that it is possible to reconstruct
some aspects of the magnetosheath global morphology using
single-spacecraft soft X-ray imaging. Plans for similar missions which
overlap with SMILE, open the possibility of multi-spacecraft tomography,
to be addressed in a separate paper.