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nei, vnei: collisional plasma, non-equilibrium, constant temperature

Non-equilibrium ionization collisional plasma model. This assumes a constant temperature and single ionization parameter. It provides a characterization of the spectrum but is not a physical model.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. xset neivers 1.0 gives the version from xspec v11.1, xset neivers 1.1 uses updated calculations of ionization fractions using dielectronic recombination rates from Mazzotta et al (1998), and xset neivers 2.0 uses the same ionization fractions as 1.1 but uses APED to calculate the resulting spectrum, and xset neivers 3.0 uses the beta release from AtomDB 3.0. Note that versions 1.x have no emission from Ar. The default is version 3.0.  

The vnei variant allows the user to set the abundances of the most common elements and vvnei allows the user to set the abundances of all elements with Z<=30.

 

For the nei version 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. Relative abundances are defined by the abund command.

par3

Ionization timescale in units of s/cm3.

par4

Redshift z

norm

 where DA is the angular diameter distance to the source (cm), and ne , nH (cm-3) are the electron and hydrogen densities respectively.

 

For the vnei variant the parameters are:

 

 

par1

Plasma temperature (keV)

par2

H abundance (should take values of 0 or 1 to switch on and off free-free continuum).

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/cm3.

par16

Redshift z

norm

 where DA is the angular diameter distance to the source (cm) , and ne , nH (cm-3) are the electron and hydrogen densities respectively.

 

For the vvnei variant the parameters are:

 

 

par1

Plasma temperature (keV)

par2

H abundance (should take values of 0 or 1 to switch on and off free-free continuum).

par3-par31

Abundances for all elements with 2 <= Z <= 30 wrt Solar (defined by the abund command)

par32

Ionization timescale in units of s/cm3.

par33

Redshift z

norm

 where DA is the angular diameter distance to the source (cm) , and ne , nH (cm-3) are the electron and hydrogen densities respectively.

 

 

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Next: Npshock Up: Additive Model Components Previous: Mkcflow