An enormous “something” more massive than a star, appears to have torn a hole in part of the Milky Way’s halo. The “dark substructure” was found in data from Gaia spacecraft observations—a mission producing the most detailed 3D map of our galaxy—with Harvard’s Ana Bonaca noticing a perturbation in a tidal stream. Bonaca is a leading authority on how the tidal field of the Milky Way galaxy disrupts globular clusters, and what the resulting debris can tell us about the underlying distribution of dark matter. (more…)
