bremss, vbremss, zbremss: thermal bremsstrahlung

A thermal bremsstrahlung spectrum based on the Kellogg, Baldwin & Koch (ApJ 199, 299) polynomial fits to the Karzas & Latter (ApJS 6, 167) numerical values. A routine from Kurucz (private communication) is used at the low temperature end. The He abundance is assumed to be 8.5 % of H by number.

The zbremss variant includes a choice of redshift and vbremss allows the H to He abundance ratio to be varied.

For bremss:

par1	plasma temperature in keV
norm	${3.02\times10^{-15}\over{4\pi D^2}} \int n_e n_I dV$, where $D$ is the distance to the source (cm) and $n_e$, $n_I$ are the electron and ion densities (cm$^{-3}$)

For zbremss:

par1	plasma temperature in keV
par2	z, redshift
norm	${3.02\times10^{-15}\over{4\pi D^2}} \int n_e n_I dV$, where $D$ is the distance to the source (cm) and $n_e$, $n_I$ are the electron and ion densities (cm$^{-3}$)

For vbremss:

par1	plasma temperature in keV
par2	$n(\mbox{He})/n(\mbox{H})$ ((note that the Solar ratio is 0.085)
norm	${3.02\times10^{-15}\over{4\pi D^2}} \int n_e n_I dV$, where $D$ is the distance to the source (cm) and $n_e$, $n_I$ are the electron and ion densities (cm$^{-3}$)