New Constraints on Dark Matter and Cosmic Neutrino Profiles through Gravity

Abstract

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 $\rho_{\rm DM}\lesssim 3.3\times 10^{-15}\;\rm kg/m^3 \simeq 6\times10^6\,\bar{\rho}_{\rm DM}$, in the vicinity of $\sim 1.1$ au (where $\bar{\rho}_{\rm DM}\simeq 0.3\;\rm GeV/cm^3$). We show that high-precision tracking data of solar system objects can constrain cosmic neutrino overdensities relative to the Standard Model prediction $\bar{n}_{\nu}$, at the level of $\eta\equiv n_\nu/\bar{n}_{\nu}\lesssim 1.7 \times 10^{11}(0.1 \;{\rm eV}/m_\nu)$ (Saturn), comparable to the existing bounds from KATRIN and other previous laboratory experiments (with $m_\nu$ the neutrino mass). 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, introducing a DM-SM long-range fifth force with a strength $\tilde{\alpha}_D$ times stronger than gravity, Bennu can set a constraint on $\rho_{\rm DM}\lesssim \bar{\rho}_{\rm DM}\left(6 \times 10^6/\tilde{\alpha}_D\right)$. These constraints can be improved in the future as the accuracy of tracking data improves, observational arcs increase, and more missions visit asteroids.

Analysis of atomic-clock data to constrain variations of fundamental constants

“…Typically it is assumed that the scalar field comprises the entirety of the dark-matter density inferred at the solar galactocentric radius R 0 ≃ 8 kpc, or the 'local density' ρ DM (R 0 ) ≈ 0.3 GeV cm −3 [87]. This figure should be taken with caution and has a large influence on the constraints, as densities from solar-system objects including planetary ephemerides [88] and more recently asteroid data [89] constrain ρ DM ≲ (10 4 -10 6 ) × ρ DM (R 0 ). The immediate implications are on the sensitivity to the couplings in equations ( 18) and ( 19), since for a generic coefficient (assuming the field saturates the total density) the sensitivity to d…”

Best-case scenarios for neutrino capture experiments

“…Parametrically, the energy shift is of order ∆E ∼ GF n0(η − η) ∼ 10 −25 eV for η = 10 11 and hence minute. 8 Matter interference effects induce an asymmetry close to the Earth's surface even when starting from a symmetric situation [21,22].…”

“…Purely gravitational probes in our Solar system put bounds of the same order, see[8] 2. Gravitational clustering of non-relativistic SM neutrinos is not expected to yield local numbers in excess of ∼ 20n0[9][10][11][12].…”

Constraints on fifth forces and ultralight dark matter from OSIRIS-REx target asteroid Bennu

“…Proof-of-principle studies have been discussed as possible ways to place model-dependent limits on a novel fifth force using asteroid and planetary precessions [138,157]. The data has also been used to obtain constraints on the local DM and cosmic neutrino densities [148]. Planetary ephemerides released by the Observatory of Paris and the Co te d'Azur Observatory (INPOP) [158,159] have also been used to constrain fifth-force ranges [160] and the effects of a finite graviton mass [161].…”