IAUS379: Dynamical Masses of Local Group Galaxies

An accurate and unambiguous determination of the inner distribution of dark matter in dwarf spheroidal (dSph) galaxies has proven to be a challenge for a few decades now. Some of the complications include the degeneracies inherent to the dynamics of stellar systems, but also the limits of the available data (e.g., just one component of the 3D space velocities of the tracers), and the need for simplifying assumptions of the analysis methods typically employed. In this contribution, we will present initial results from applying our fully discrete axisymmetric Schwarzschild code to this problem. We first study mock datasets for dSph galaxies from the Gaia Challenge, which help us identify the pros and cons on the tool we use, and understand the limits imposed by the degeneracies inherent to the problem. We explore datasets of various sizes, and all combination of available velocity components, i.e., only line-of-sight velocities, only proper motions, and both. Our methodology also avoids restrictive assumptions about the degree of orbital (an)isotropy. We then apply the tool to line-of-sight velocity data for the Sculptor and Fornax dwarfs, and compare our preliminary results to published work.