Astrophysical Plasmas and Atomic Processes

Abstract

Several plasma codes are available for the analysis of hot astrophysical plasmas. Among the oldest are the Raymond-Smith model (Raymond & Smith 1977) and Mewe-Gronenschild model (Mewe et al. 1985, 1986). Minor updates to this last code have resulted in the meka model (Kaaatra 1992); major updates (most importantly the ionization balance and the treatment of the Fe-L complex) resulted in the mekal code (Mewe, Kaastra & Liedahl 1995). Here also the plasma codes of Masai (1984) and Landini & Monsignori Fossi (1990) should be mentioned. The RS, meka and mekal codes are included in the XSPEC fitting package, the latest mekal code is incorporated in the SPEX package (Kaastra et al. 1996). Both Masai’s code and SPEX contain non-equilibrium ionization (NEI) modes. AU these codes differ in details, see Brickhouse et al. (1995) for an overview. Most important for the analysis of X-ray data is the ionization balance that is used for iron and the treatment of the Fe-L complex.