Deproject is a CIAO Sherpa extension package to facilitate
deprojection of two-dimensional annular X-ray spectra to recover the
three-dimensional source properties. For typical thermal models this would
include the radial temperature and density profiles. This basic method
has been used extensively for X-ray cluster analysis and is the basis for the
XSPEC model projct. The deproject module brings this
functionality to Sherpa as a Python module that is straightforward to use and
understand.
The basic physical assumption of deproject is that the extended source
emissivity is constant and optically thin within spherical shells whose radii
correspond to the annuli used to extract the specta. Given this assumption one
constructs a model for each annular spectrum that is a linear volume-weighted
combination of shell models.