Jaffe profile

The Jaffe profile (or Jaffe model) is a mathematical function that is used to describe the distribution of mass or light in elliptical galaxies and the bulges of spiral galaxies. It was proposed by Walter Jaffe in 1983. Its usefulness derives from the fact that it accurately reproduces a de Vaucouleurs profile when projected onto the sky.

The density in the Jaffe model is given by

${\displaystyle \rho (r)={\rho _{0} \over 4\pi }\left({r \over r_{0}}\right)^{-2}\left(1+{r \over r_{0}}\right)^{-2}.}$

In this equation, ${\displaystyle \rho _{0}}$ and ${\displaystyle r_{0}}$ are parameters that can be varied to fit the observed density.

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