Skip to main content

The NASA/GSFC network is currently experiencing intermittent issues that affect our services. We are working on it and apologize for the inconvenience.
The offline tool hark (also on github) can be used to find and download data from the cloud.

Xspec Home Page

next up previous contents
Next: meka, vmeka: emission, hot Up: Additive Model Components Previous: logpar, zlogpar: log-parabolic blazar   Contents


lorentz, zlorentz: lorentz line profile

A Lorentzian line profile.

$\displaystyle A(E) = K{\sigma\over{(\pi-2\arctan(-2E_L/\sigma))}}{1\over{(E-E_L)^2 + (\sigma/2)^2}} $

where:

par1 $E_L$, line energy in keV
par2 $\sigma$, FWHM line width in keV
norm $K$, photons/cm$^2$/s in the line

For zlorentz the corresponding formula is:

$\displaystyle A(E) = {K\over{(1+z)}}{\sigma\over{(\pi-2\arctan(-2E_L/\sigma))}}{1\over{(E(1+z)-E_L)^2 + (\sigma/2)^2}} $

and the parameters are:

par1 $E_L$, line energy in keV
par2 $\sigma$, FWHM line width in keV
par3 $z$, redshift
norm $K$, photons/cm$^2$/s in the line

The line is calculated out to fifty sigmas. Note also that the normalization is defined as the integral over energies greater than zero since negative energies are unphysical.