Estimating the dark matter halo mass of our Milky Way using dynamical
  tracers
  The mass of the dark matter halo of the Milky Way can be estimated by fitting
analytical models to the phase-space distribution of dynamical tracers. We test
this approach using realistic mock stellar halos constructed from the Aquarius
N-body simulations of dark matter halos in the $\Lambda$CDM cosmology. We
extend the standard treatment to include a Navarro-Frenk-White (NFW) potential
and use a maximum likelihood method to recover the parameters describing the
simulated halos from the positions and velocities of their mock halo stars. We
find that the estimate of halo mass is highly correlated with the estimate of
halo concentration. The best-fit halo masses within the virial radius,
$R_{200}$, are biased, ranging from a 40\% underestimate to a 5\% overestimate
in the best case (when the tangential velocities of the tracers are included).
There are several sources of bias. Deviations from dynamical equilibrium can
potentially cause significant bias; deviations from spherical symmetry are
relatively less important. Fits to stars at different galactocentric radii can
give different mass estimates. By contrast, the model gives good constraints on
the mass within the half-mass radius of tracers even when restricted to tracers
within 60kpc. The recovered velocity anisotropies of tracers, $\beta$, are
biased systematically, but this does not affect other parameters if tangential
velocity data are used as constraints.
