This movie follows the progenitor of a tidal stream orbiting a simulated Milky Way-like galaxy for 8 billion years. The red particles show the dark matter from a cosmological simulation and the green particles show a disrupting globular cluster. The stars near the progenitor form a characteristic "S"-shape due to the gravitational influence of the globular cluster. Once stripped from the globular cluster, the stars form long stellar streams which roughly follow the orbit of the globular cluster. We can use these streams to measure the mass distribution and clumpiness of dark matter in the Milky Way, as well as the accretion history of our Galaxy. We have recently measured the properties of 12 such streams in Li et al. 2022 ([ Ссылка ]).

For reference, the bar at the top shows a length scale of 50 kpc (roughly 160,000 light years). Time is shown by the scale factor which goes from a=0.5 (8 Gyr ago) to a=1 (the present).

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