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Today's Colloquium: Probing the Milky Way's dark-matter distribution with tidal streams

Submitter: Robyn Sanderson Grier (Kapteyn Institute)
Description: Tidal streams can reveal the distribution of dark matter in the Milky Way on many scales. The orbits of streams can constrain the shape and large-scale mass distribution of the dark halo, while the internal dynamics of streams may encode information about the distribution of dark subhalos. I will discuss how the unprecedented accuracy of Gaia's proper-motion measurements will give us unprecedented sensitivity to the structure of the dark Milky Way.

The figure shows a Gaia's-eye view (Aitoff plot in Galactic coordinates) of mock stellar streams used to test a new method for constraining the Galactic potential. Each colour denotes a stream from a different satellite galaxy. The streams are selected from a distribution whose number, size, and radial distribution mimics what we expect for the Milky Way, convolving with the expected errors from the Gaia mission, and making cuts in data quality and estimated total energy.
Copyright: Robyn Sanderson Grier
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