Accurate Masses for Navarro-Frenk-White Dark Matter Haloes

We consider the problem of estimating the virial mass of a dark halo from the positions and velocities of a tracer population. Although a number of general tools are available, more progress can be made if we are able to specify the functional form of the halo potential (although not its normalization). Here, we consider the particular case of the cosmologically motivated Navarro-Frenk-White (NFW) halo and develop two simple estimators. We demonstrate their effectiveness against numerical simulations and use them to provide new mass estimates of Carina, Fornax, Sculptor, and Sextans dSphs.