Sérsic profile

Summary

The Sérsic profile is a family of functions for the surface brightness of a galaxy. It describes how the brightness falls off with the projected distance from the centre. It has the form $I(R) = I_e \exp\left(-b_n \left[ (R/R_e)^{1/n} - 1 \right]\right)$, where the Sérsic index $n$ controls the shape. The index $n = 1$ gives the exponential profile of galactic disks, and $n = 4$ gives the de Vaucouleurs profile of elliptical galaxies. It is the standard parametric model in the photometry of galaxies.