Constraints on Galileon-induced precessions from solar system orbital motions

TL;DR

This paper uses precise solar system orbital data to set constraints on Galileon field effects, including a screened correction to gravity and a galactic gradient influence, refining bounds on these modifications to gravity.

Contribution

It provides the first observational constraints on Galileon-induced precessions in the solar system using planetary data.

Findings

Galileon correction parameter α <= 0.3 from Mars data

Unscreened galactic gradient parameter ξ <= 0.004 from Saturn precession

Constraints improve understanding of modified gravity effects in the solar system

Abstract

We use latest data from solar system planetary orbital motions to put constraints on some Galileon-induced precessional effects. Due to the Vainshtein mechanism, the Galileon-type spherically symmetric field of a monopole induces a small, screened correction proprtional to \sqrt{r} to its usual r^-1 Newtonian potential which causes a secular precession of the pericenter of a test particle. In the case of our solar system, latest data from Mars allow to constrain the magnitude of such an interaction down to \alpha <= 0.3 level. Another Galileon-type effect which might impact solar system dynamics is due to an unscreened constant gradient induced by the peculiar motion of the Galaxy. The magnitude of such an effect, depending on the different gravitational binding energies of the Sun and the planets, is \xi <= 0.004 from the latest bounds on the supplementary perihelion precession of Saturn.