Inferring the gravitational potential of the Milky Way with a few precisely measured stars

Understand

The dark matter halo of the Milky Way is expected to be triaxial and filled with substructure.

• It is hoped that streams or shells of stars produced by tidal disruption of stellar systems will provide precise measures of the gravitational potential to test these predictions.
• We develop a method for inferring the Galactic potential with tidal streams based on the idea that the stream stars were once close in phase space.
• Our method can flexibly adapt to any form for the Galactic potential: it works in phase-space rather than action-space and hence relies neither on our ability to derive actions nor on the integrability of the potential.