Using Stellar Streams to Probe the Shape of the Milky Way's Dark Matter Halo

The nature of dark matter is one of the major questions in cosmology. So far, cold dark matter (CDM) is the most popular model, where CDM cosmoglocial simulations predict asymmetric dark matter haloes around galaxies. Stellar streams consist of stars originating from a dwarf galaxy or a globular cluster that trail ahead or behind the progenitor's orbit about its host galaxy to create a long, thin structure, making them excellent tracers of the gravitational potential. We analyze 6 stellar streams originating from globular clusters: NGC 288, NGC 1261, NGC 1851, NGC 2298, NGC 3201, and NGC 7089, starting with the progenitor's 6D phase space coordinates, we created stream models in the fiducial Milky Way potential, which has a stellar disk, nucleus, and bulge as well as a spherically symmetric Navarro-Frenk-White (NFW) halo. We find that this potential cannot explain the shape of every stream we observe. Furthermore, we show that a triaxial halo tilted with respect to the Galactic plane will have a noticeable effect on stream positions and velocities. We discuss halo shapes best in simultaneously reproducing the six streams in our sample and how they compare to the expected asymmetry in CDM halos.