equil, vequil: collisional plasma, ionization equilibrium

Ionization equilibrium collisional plasma model. This is the equilibrium version of Kazik Borkowski's NEI models. 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 equil model the parameters are:

par1 | plasma temperature (keV) |

par2 | 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 |

par3 | redshift |

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 vequil model, the parameters are:

par1 | plasma temperature (keV) |

par2-par13 | Abundances for He, C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni wrt Solar (defined by the abund command) |

par14 | Redshift, z |

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 this model are as follows:

Borkowski, Lyerly & Reynolds (2001)

Hamilton, Sarazin & Chevalier (1983)

Borkowski, Sarazin & Blondin (1994)

Liedahl, Osterheld & Goldstein (1995)