A spectral code for X-ray spectra of supernova remnants.

We present a spectral code for the calculation of nonequilibrium spatially resolved X-ray spectra of SNR. The code is based upon eigenvalue decomposition of the transition rates matrix and discretization of the transition rates. The transition rates are taken from the compilation of Arnaud and Rothenflug (1985). The X-ray spectra are calculated using an updated version of the Mewe and Gronenschild code and include nearly 2500 spectral lines. For the hydrodynamics we used several self-similar models, either adiabatic, isothermal, or isentropic and both with and without a reverse shock. The resulting code proves to be fast enough for spectral fitting purposes. We give a few illustrative examples based upon Cas A like spectra and summarize the scaling laws for the X-ray spectra.