Spherical Jeans equation

For a steady nonrotating spherical system,It relates radial pressure, velocity anisotropy, and the gravitational field.

For tracer density $\nu \propto r^{-\alpha }$, circular speed $V_c\propto r^{\gamma }$, and constant anisotropy $\beta$, the boundary-free scale-free solution iswhich requires a positive denominator.

The mass--anisotropy--density degeneracy is the ability of different gravitational mass profiles, tracer-density profiles, and orbital-anisotropy profiles to predict similar projected tracer kinematics through the Jeans equation.