An alternative method for fitting XSTAR results to observed spectra within xspec is to use the xspec `analytic' model warmabs. This actually includes several separate models: warmabs, photemis, hotabs, hotemis, windabs and multabs. These are described below.
This model allows the use of xspec models for warm absorbers and photoionized emitters, and for coronal equilibrium absorbers and emitters without requiring construction of mtables or etables. The advantages of this procedure include:
1) Circumventing the intrinsic approximations associated with use of tables for absorption with variable abundances treated as multiplicative parameters. (see the `Important Notes on Mtables' section of the xstar2xspec chapter of the xstar manual). Warmabs/photemis/windabs/multabs calculate spectra using stored level populations which are then scaled using element abundances specified during the xspec session before the spectra are calculated. Therefore the approximations associated with the use of tables are avoided. (However, see the section below on the current limitations of these models).
2) Circumventing the intrinsic clumsiness of the use of tables.
3) Ability to use arbitrary spectral resolution, not limited by the internal xstar spectral resolution
3.5) Allows the use of turbulent broadening as a fitting parameter in xspec.
4) This model employs the most recent updates to xstar and the database, version 2.2.