IAUS379: Dynamical Masses of Local Group Galaxies

Our Galaxy, the Milky Way, provides us with a unique opportunity to measure the 3D shape of its dark-matter halo, thus testing the properties of the dark sector and the fundamental cosmological model. Until recently, however, these efforts have been thwarted by the scarcity of observational data, especially in the outer halo, as well as reliance on the assumption of a dynamical equilibrium, resulting in estimates of the total Milky Way mass spanning a factor of a few. I will discuss how the 6D phase-space data from the Gaia mission and ground-based surveys, combined with novel modeling methods, have been used to precisely map not just the Milky Way's halo at the present, but also reconstruct its accretion history.