New Constraints on Dark Matter and Cosmic Neutrino Profiles through Gravity*

We derive purely gravitational constraints on dark matter and cosmic neutrino profiles in the solar system using asteroid (101955) Bennu. We focus on Bennu because of its extensive tracking data and high-fidelity trajectory modeling resulting from the OSIRIS-REx mission. We find that the local density of dark matter is bound by ρ_DM < 3.3 × 10^-15 kg/m ≅ 6 × 10⁶ ρ_avg,DM  in the vicinity of ~ 1.1 au (where ρ_avg,DM ≅ 0.3 GeV/cm³). We show that high-precision tracking data of solar system objects can constrain cosmic neutrino overdensities relative to the Standard Model prediction at a level comparable to the existing bounds from KATRIN and other previous laboratory experiments. These local bounds have interesting implications for existing and future direct-detection experiments. Our constraints apply to all dark matter candidates but are particularly meaningful for scenarios including solar halos, stellar basins, and axion miniclusters, which predict overdensities in the solar system. Furthermore, Bennu can also set a constraint on ρ_DM if a DM-SM long-range fifth force with a strength α_D times stronger than gravity exists. These constraints can be improved in the future as the accuracy of tracking data improves, observational arcs increase, and more missions visit asteroids.