  The density profiles of dark matter halos are often modeled by an approximate
solution to the isothermal Lane-Emden equation with suitable boundary
conditions at the origin. It is shown here that such a model corresponds to an
exact solution of the Einstein-Maxwell equations for exotic charged dust. It is
also shown that, because of its necessarily very small charge to mass ratio,
the fact that the particles are charged does not necessarily rule out such
material as a candidate for dark matter.
