Vgau: gaussian velocity broadening model

This multiplicative model broadens an arbitrary additive component with a Gaussian Doppler profile, characterized by the Gaussian \(\sigma\). The broadening kernel is therefore proportional to \(e^{\displaystyle{-(c^2/2\sigma^2)(E-E_0)^2/E_0^2}}\).

The parameters of the model are:

sig : Gaussian velocity broadening \(\sigma\), in km/s. Default value: 1 km/s