gnei, vgnei, vvgnei: collisional plasma, non-equilibrium, temperature evolution

Non-equilibrium ionization collisional plasma model. This is a
generalization of the nei model where the temperature is allowed to
have been different in the past i.e. the ionization timescale averaged
temperature is not necessarily equal to the current temperature. For
example, in a standard Sedov model with equal electron and ion
temperatures, the ionization timescale averaged temperature is always
higher than the current temperature for each fluid element. The
references for this model can be found under the description of the
equil model. Several versions are available. To switch between them
use the xset **neivers** command. The versions available are:

1.0 | the version from xspec v11.1 |

1.1 | as 1.0 but with updated ionization fractions using dielectronic recombination rates from Mazzotta et al. (1998) |

2.0 | same ionization fractions as 1.1 but uses AtomDB v2 to calculate the resulting spectrum |

3.x | ionization fractions and spectrum calculation uses AtomDB v3.x |

Note that versions 1.x have no emission from Ar. For versions 3.x and later additional xset options are available and are listed under the documentation for nei.

For the gnei model the parameters are:

par1 | plasma temperature (keV) |

par2 | Metal abundances (He fixed at cosmic). The elements included are C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni. Abundances are defined by the abund command |

par3 | Ionization timescale in units of s/cm. |

par4 | Ionization timescale averaged plasma temperature (keV) |

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 vgnei model, the parameters are:

par1 | plasma temperature (keV) |

par2 | H abundance (set to 0 for no free-free continuum, otherwise 1) |

par3-par14 | Abundances for He, C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni wrt Solar (defined by the abund command) |

par15 | Ionization timescale in units of s/cm. |

par16 | Ionization timescale averaged plasma temperature (keV) |

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 vvgnei model, the parameters are:

par1 | plasma temperature (keV) |

par2 | H abundance (set to 0 for no free-free continuum, otherwise 1) |

par3-par31 | Abundances for all elements with 2 Z 30 wrt Solar (defined by the abund command) |

par32 | Ionization timescale in units of s/cm. |

par33 | Ionization timescale averaged plasma temperature (keV) |

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). |