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npshock, vnpshock, vvnpshock: 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. 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
3.0 ionization fractions and spectrum calculation uses AtomDB v3

Note that versions 1.x have no emission from Ar. The default is version 3.0. The vnpshock variant allows the user to set the abundances for the more common elements. For versions 3 and above the abundances of the trace elements (ie Li, Be, B, F, Na, P, Cl, K, Sc, Ti, V, Cr, Mn, Co, Cu, Zn) can be set using xset APEC_TRACE_ABUND. These trace element abundances can be set either to the abundance of one of the main elements or to a numerical value (relative to Solar). For instance,

XSPEC12> xset APEC_TRACE_ABUND Fe
sets trace element abundances to that of iron while
XSPEC12> xset APEC_TRACE_ABUND 1.0
sets them to Solar. The default value for APEC_TRACE_ABUND is 1.0. Full control over all the elemental abundances is available in the vvnpshock model.

For the npshock model the parameters 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 defined by the abund command
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
norm $(10^{-14}/(4\pi[D_A(1+z)]^2))\int n_en_H dV$, where $D_A$ is the angular diameter distance to the source (cm), $n_e$ is the electron density (cm$^{-3}$), and $n_H$ is the hydrogen density (cm$^{-3}$).

For the vnpshock model, the parameters are:

par1 Mean shock temperature (keV)
par2 Electron temperature immediately behind the shock front (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 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 $(10^{-14}/(4\pi[D_A(1+z)]^2))\int n_en_H dV$, where $D_A$ is the angular diameter distance to the source (cm), $n_e$ is the electron density (cm$^{-3}$), and $n_H$ is the hydrogen density (cm$^{-3}$).

Finally, for the vvnpshock model, the parameters are:

par1 Mean shock temperature (keV)
par2 Electron temperature immediately behind the shock front (keV)
par3 H abundance (set to 0 for no free-free continuum, otherwise 1)
par4-par32 Abundances for all elements with 2 $\leq$ Z $\leq$ 30 wrt Solar (defined by the abund command)
par33 Lower limit on ionization timescale in units of s/cm$^3$.
par34 Upper limit on ionization timescale in units of s/cm$^3$.
par35 Redshift, z
norm $(10^{-14}/(4\pi[D_A(1+z)]^2))\int n_en_H dV$, where $D_A$ is the angular diameter distance to the source (cm), $n_e$ is the electron density (cm$^{-3}$), and $n_H$ is the hydrogen density (cm$^{-3}$).


next up previous contents
Next: nsa: neutron star atmosphere Up: Additive Model Components Previous: nlapec: continuum-only APEC emission