Weighing the Milky Way using Tidal Tails of Globular Clusters

The distribution of mass within the Milky Way halo is an important but largely unknown quantity. Stellar streams of Galactic satellites, such as the Sagittarius stream, offer a possibility to infer the Galactic mass distribution. Such streams trace their progenitor’s orbits about the Galaxy. From numerical modeling of stellar streams we can gain orbital information of the progenitor satellite and, finally, deduce the underlying Galactic mass distribution. I will demonstrate that the most powerful streams for measuring the Galactic mass distribution are tidal tails originating from globular clusters. These tidal tails are kinematically much colder and thinner than, e.g., the Sagittarius stream. Hence, they yield tighter orbital constraints. In addition, globular cluster tidal tails exhibit dynamical substructures, which contain unique orbital information. Using the example of the outer-halo globular cluster Palomar 5, I will show how this information can be extracted and used to weigh the Milky Way.

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