Constraining dark matter sub-structure with the dynamics of astrophysical systems

Abstract

The accuracy of the measurements of some astrophysical dynamical systems allows to constrain the existence of incredibly small gravitational perturbations. In particular, the internal Solar System dynamics (planets, Earth-Moon) opens up thepossibility, for the first time, to prove the abundance, mass and size, of dark sub-structures at the Earth vicinity. We find that adoptingthe standard dark matter density, its local distribution can be composed by sub-solar mass halos with no currently measurabledynamical consequences, regardless of the mini-halo fraction. On the other hand, it is possible to exclude the presence of darkstreams with linear mass densities higher than λst > 10−10M☉/AU (about the Earth mass spread along the diameter of the SS upto the Kuiper belt). In addition, we review the dynamics of wide binaries inside the dwarf spheroidal galaxies in the Milky Way. The dynamics of suchkind of binaries seem to be compatible with the presence of a huge fraction of dark sub-structure, thus their existence is not a sharp discriminant ofthe dark matter hypothesis as been claimed before. However, there are regimes where the constraints from different astrophysical systems may revealthe sub-structure mass function cut-off scale.