gauss, zgauss: gaussian line profile

A simple gaussian line profile. If the width is $\leq 0$ then it is treated as a delta function. The zgauss variant computes a redshifted gaussian.

$$A(E) = K{2\over{\sigma\sqrt{2\pi}(1-\mathit{erf}(-E_l/(\sqrt{2}\sigma)))}} \exp\left({-(E-E_l)^2\over{2\sigma^2}}\right)$$

where:

par1	$E_l$, line energy in keV
par2	$\sigma$, line width in keV
Norm	$K$, total photons/cm$^2$/s in the line

For zgauss the corresponding formula is:

$$A(E) = K{1\over{(1+z)\sigma\sqrt{2\pi}(1-\mathit{erf}(-E_l/(\sqrt{2}\sigma)))}} \exp\left({-(E(1+z)-E_l)^2\over{2\sigma^2}}\right)$$

and parameter settings are:

par1	$E_l$, source frame line energy in keV
par2	$\sigma$, source frame line width in keV
par3	$z$, redshift
Norm	$K$, source frame total photons/cm$^2$/s in the line

The line is truncated at the point that the integrated flux under the line is within a critical value of the total flux. This critical value can be changed using xset LINECRITLEVEL. The default critical value is $1.0\times10^{-8}$. Note also that the normalization is defined as the integral over energies greater than zero since negative energies are unphysical.

HEASARC Home | Observatories | Archive | Calibration | Software | Tools | Students/Teachers/Public

Last modified: Friday, 23-Aug-2024 13:20:40 EDT

HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.