Action-space clustering of tidal streams to map the Galactic potential

Given a parametrized model of the Galactic potential, the best-fit parameters can be obtained by maximizing the Kullback-Leibler divergence of the action distribution of a set of stars initially clustered in action space (e.g. stars in tidal streams). This method will allow us to map the Milky Way's gravitational potential by simultaneously fitting multiple tidal streams without requiring stream membership information. With 20 streams of at least 20 stars each, including observational errors consistent with predictions for Gaia, this technique recovers the input potential parameters to a precision of 10-60% and an accuracy of 10%. With all the observed streams in our mock stellar halo (about 40) that fit the error criteria, the precision improves to 10%.