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 |

par3 | Metal abundances (He fixed at that defined by the abund command). 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 | , where is the angular diameter distance to the source (cm), is the volume element (cm), and and are the electron and H densities (cm), respectively |

For the vmekal variant the parameters are as follows.

par1 | plasma temperature in keV |

par2 | H density (cm |

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 | , where is the angular diameter distance to the source (cm), is the volume element (cm), and and are the electron and H densities (cm), 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)