The mass of the Milky Way (MW) is important to the formation and evolution of galaxy. After decades of study, the mass of dark matter halo is still open. Most studies have used dynamical tracers in the inner regions of the halo, relying on extrapolations to estimate the mass of the MW. In our study, we determine the Milky Way mass distribution from fitting dynamical models to the gravitational force field and the Galactic rotation curve. Based on RR Lyrae with accurate proper motions and classification in Gaia DR3, we obtain the distance with relative uncertainty less than 5% by using the extinction-free Period-Wesenheit relation. Applying Gaussian Mixture Model to the intrinsic velocity distribution, we present the result of a multi-component kinematic model of RR Lyrae in the inner regions. Considering the early accretion history of the MW so that the stellar halo may not be in equilibrium, we separate the halo population into an isotropic stellar halo and the radially-anisotropic population relevant to a merge event. With a Bayesian method, we fit the potential model parameters, including the density flattening of the dark matter (DM) halo.
In this talk, I shall discuss our best-fitting results about the shape and DM halo mass.
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