rnei, vrnei, vvrnei: non-equilibrium recombining collisional plasma

Non-equilibrium ionization collisional plasma model. This is a model
for a recombining plasma where the plasma is
assumed to have started in collisional equilibrium with the initial
temperature given by the relevant input parameter. This model will
only work for xset **neivers 3.0** and above. Additional
xset options are available and are listed under the
documentation for nei.

For the rnei model the parameters are:

par1 | Plasma temperature (keV) |

par2 | Initial plasma temperature (keV) |

par3 | Metal abundances (He fixed at that defined by the abund command). The elements included are C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni. Abundances are defined by the abund command |

par4 | Ionization timescale in units of s/cm. |

par5 | redshift |

norm | , where is the angular diameter distance to the source (cm), is the electron density (cm), and is the hydrogen density (cm). |

For the vrnei model, the parameters are:

par1 | Plasma temperature (keV) |

par2 | Initial plasma temperature (keV) |

par3 | H abundance (set to 0 for no free-free continuum, otherwise 1) |

par4-par15 | Abundances for He, C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni wrt Solar (defined by the abund command) |

par16 | Ionization timescale in units of s/cm. |

par17 | Redshift, z |

norm | , where is the angular diameter distance to the source (cm), is the electron density (cm), and is the hydrogen density (cm). |

Finally, for the vvrnei model, the parameters are:

par1 | Plasma temperature (keV) |

par2 | Initial plasma temperature (keV) |

par3 | H abundance (set to 0 for no free-free continuum, otherwise 1) |

par4-par32 | Abundances for all elements with 2 Z 30 wrt Solar (defined by the abund command) |

par33 | Ionization timescale in units of s/cm. |

par34 | Redshift, z |

norm | , where is the angular diameter distance to the source (cm), is the electron density (cm), and is the hydrogen density (cm). |