Binary stars as probes of dark substructures in dwarf galaxies

Understand

We use analytical and N-body methods to examine the survival of wide stellar binaries against repeated encounters with dark substructures orbiting in the dark matter haloes of dwarf spheroidal galaxies (dSphs).

• Our models adopt cosmologically-motivated conditions wherein dSphs are dark-matter dominated systems that form hierarchically and orbit about a host galaxy.
• Our analytical estimates show that wide binaries are disrupted at a rate that is proportional to the local density of dark substructures averaged over the life-time of the binary population.
• The fact that external tides can efficiently strip dark substructures from the outskirts of dSphs implies that the present number and distribution of binaries is strongly coupled with the mass evolution of individual galaxies.