mekal, vmekal: emission, hot diffuse gas (Mewe-Gronenschild-Kaastra)

An emission spectrum from hot diffuse gas based on the model calculations of Mewe and Kaastra with Fe L calculations by Liedahl. The model includes line emissions from several elements. The switch parameter determines whether spectrum is calculated by running the mekal code, by interpolating on a pre-calculated mekal table, or using the AtomDB data. Relative abundances are set by the abund command for the mekal model. The vmekal variant allows the user to set the individual abundances for the model.

For the mekal model the parameters are:

par1	plasma temperature in keV
par2	H density (cm$^{-3}$
par3	Metal abundances (He fixed at cosmic). The elements included are C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, Ni. Relative abundances are set by the abund command.
par4	Redshift, z
par5	Switch (0 = calculate, 1 = interpolate, 2 = interpolate using AtomDB data)
norm	${10^{-14}\over{4\pi[D_A(1+z)]^2}}\int n_en_HdV$, where $D_A$ is the angular diameter distance to the source (cm), $n_e$ and $n_H$ are the electron and H densities (cm$^{-3}$), respectively

For the vmekal variant the parameters are as follows.

par1	plasma temperature in keV
par2	H density (cm$^{-3}$
par3-par16	Abundances for He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, Ni wrt Solar (defined by the abund command).
par17	redshift, z
par18	Switch (0 = calculate, 1 = interpolate, 2 = interpolate using AtomDB data)
norm	${10^{-14}\over{4\pi[D_A(1+z)]^2}}\int n_en_HdV$, where $D_A$ is the angular diameter distance to the source (cm), $n_e$ and $n_H$ are the electron and H densities (cm$^{-3}$), respectively

The references for the meka model are as follows :
Mewe, Gronenschild & van den Oord (1985)
Mewe, Lemen, & van den Oord (1986)
Kaastra, J.S. 1992, An X-Ray Spectral Code for Optically Thin Plasmas (Internal SRON-Leiden Report, updated version 2.0)
Liedahl, Osterheld & Goldstein (1995)

Similar credit may also be given for the adopted ionization balance:
Arnaud & Rothenflug (1985)
Arnaud & Raymond (1992)