nlapec: continuum-only APEC emission spectrum

A continuum-only emission spectrum from collisionally-ionized diffuse gas calculated using the ATOMDB code. More information can be found at which should be consulted by anyone running this model. This default version number can be changed by modifiying the ATOMDB_VERSION string in your Xspec.init file.

See the documentation on the apec model for a list of the xset options which can be used to change the behaviour of the apec code.

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, Al, Si, S, Ar, Ca, Fe, Ni. Relative abundances are set by the abund command. The trace element abundances are from xset APEC_TRACE_ABUND, the default is 1.0.
par3 Redshift, z
norm $\frac{10^{-14}}{4\pi[D_A(1+z)]^2}\int \eta_e\eta_H \mathrm{d}V$, where $D_A$ is the angular diameter distance to the source (cm), $\eta_e$ and $\eta_H$ are the electron and H densities (cm$^{-3}$)