Dark Matter Debris Flows in the Milky Way

Abstract

We show that subhalos falling into the Milky Way create a flow of tidally-stripped debris particles near the galactic center with characteristic velocity behavior. In the Via Lactea-II N-body simulation, this unvirialized component constitutes a few percent of the local density and has velocities peaked at 340 km/s in the solar neighborhood. Such velocity substructure has important implications for surveys of low-metallicity stars, as well as direct detection experiments sensitive to dark matter with large scattering thresholds.

Comments: 4 pages, 3 figures; v2 includes new plots illustrating the radial and tangential velocities of non-debris particles; v3 includes some additional minor edits