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Using Tidal Streams To Constrain Halo Minor Axis

Presentation #203.06 in the session Mapping and Modeling the Milky Way’s Tidal Streams.

Published onApr 25, 2022
Using Tidal Streams To Constrain Halo Minor Axis

Recent studies have shown that there is a significant misalignment between the minor axis of the Milky Way (MW) outer halo and the direction perpendicular to the central stellar disk. In this work, we test a method to constrain the minor axis of the host dark matter halo using a set of simulated tidal streams within MW-mass halos from the FIRE cosmological simulations. Our method is complementary to other traditional methods such as orbit fitting. Utilizing angle and frequency variables, we show that we can find a galactic direction that yields minimal offset between the slopes of the line overdensities in these two subspaces, and it is in good agreement with the actual location of the host dark matter halo’s minor axis at distance scales comparable to the average distance of stream members. We apply this method to the Sagittarius stream in the MW. We report that the MW halo is prolate (q ~ 0.7–0.9) and find evidence that the minor axis of the MW halo lies close to the plane of the stellar disk, in agreement with findings from other work.

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