npshock, vnpshock: shocked plasma, plane parallel, separate ion, electron temperatures.

Plane-parallel shock plasma model with separate ion and electron temperatures. This model is slow. par1 provides a measure of the average energy per particle (ions+electrons) and is constant throughout the postshock flow in plane shock models (Borkowski et al., 2001, ApJ, 548, 820). par2 should always be less than par1. If par2 exceeds par1 then their interpretations are switched (ie the larger of par1 and par2 is always the mean temperature). Additional references can be found under the help for 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 (1988), and xset neivers 2.0 uses the same ionization fractions as 1.1 but uses APED to calculate the resulting spectrum. Note that versions 1.x have no emission from Ar. The default is version 1.1.

 

The npshock version uses relative abundances from the Anders & Grevesse (1993) mix, while the vpnshock version allows the user to set the abundances.

 

Parameters for npshock are:

 

par1	Mean shock temperature (keV)
par2	electron temperature immediately behind the shock front (keV)
par3	Metal abundances (He fixed at cosmic). The elements included are C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni. Abundances are given by the Anders & Grevesse mixture.
par4	Lower limit on ionization timescale in units of s cm–3.
par5	Upper limit on ionization timescale in units of s cm–3.
par6	redshift z
norm	where DA is the angular size distance to the source (cm) , and ne , nH (cm-3) are the electron and hydrogen densities respectively.

 

For vnpshock the parameters are:

 

 

par1	Mean shock temperature (keV)
par2	electron temperature immediately behind the shock front (keV)
par3	H density in cm-3
par4-par15	Abundances for He, C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni wrt Solar (given by the Anders & Grevesse mixture)
par16	Lower limit on ionization timescale in units of s cm–3.
par17	Upper limit on ionization timescale in units of s cm–3.
par18	redshift z
norm	where DA is the angular size distance to the source (cm) , and ne , nH (cm-3) are the electron and hydrogen densities respectively.