K-mouflage gravity models that pass Solar System and cosmological constraints

TL;DR

This paper demonstrates that Solar System tests impose strong constraints on K-mouflage gravity models, but viable models with distinct cosmological predictions remain possible and testable by future observations.

Contribution

It provides new constraints on K-mouflage models from Solar System tests and shows that models consistent with these constraints can still produce observable cosmological deviations.

Findings

Solar System tests strongly constrain K-mouflage models

Coupling strength β must be less than 0.1

Models predict percent-level deviations in matter clustering

Abstract

We show that Solar System tests can place very strong constraints on K-mouflage models of gravity, which are coupled scalar field models with nontrivial kinetic terms that screen the fifth force in regions of large gravitational acceleration. In particular, the bounds on the anomalous perihelion of the Moon imposes stringent restrictions on the K-mouflage Lagrangian density, which can be met when the contributions of higher-order operators in the static regime are sufficiently small. The bound on the rate of change of the gravitational strength in the Solar System constrains the coupling strength $\beta$ to be smaller than $0.1$. These two bounds impose tighter constraints than the results from the Cassini satellite and Big Bang Nucleosynthesis. Despite the Solar System restrictions, we show that it is possible to construct viable models with interesting cosmological predictions. In particular, relative to $\Lambda$-CDM, such models predict percent-level deviations for the clustering of matter and the number density of dark matter haloes. This makes these models predictive and testable by forthcoming observational missions.