wndabs, zwndabs: photo-electric absorption, warm absorber

Photo-electric absorption from approximation to a warm absorber using Balucinska-Church & McCammon (1992) cross-sections. Relative abundances are set by the abund command.

$$M(E) = \begin{array}{ll} 1 & E > E_w \\ [.2cm] \exp[-\eta_H\sigma(E)] & E \leq E_w \end{array}$$

where $\sigma(E)$ is the photo-electric cross-section (NOT including Thomson scattering) and

par1=$\eta_H$	equivalent hydrogen column (in units of $10^{22}$ atoms cm$^{-2}$)
par2=$E_w$	window energy (keV)

The zwndabs variant allows the user to specify a (fixed) redshift and uses the corresponding formula:

$$M(E) = \begin{array}{ll} 1 & E > E_w \\ [.2cm] \exp[-\eta_H\sigma(E[1+z])] & E \leq E_w \end{array}$$

with parameters:

par1=$\eta_H$	equivalent hydrogen column (in units of $10^{22}$ atoms cm$^{-2}$)
par2=$E_w$	window energy (keV)
par3=z	redshift