Astronomical constraints on some long-range models of modified gravity

TL;DR

This study uses planetary perihelion precession data to test and constrain various long-range modified gravity models, ruling out some and partially testing others, to better understand dark energy and dark matter.

Contribution

It provides analytical expressions for perihelion precessions induced by specific modified gravity models and compares them with observational data to constrain these theories.

Findings

Curvature invariants-based models are ruled out by planetary data.

DGP model remains less constrained, with only the Lense-Thirring effect passing the test.

Re-scaling errors does not reconcile some models with observations.

Abstract

In this paper we use the corrections to the usual Newton-Einstein secular precessions of the perihelia of the inner planets of the Solar System, phenomenologically estimated as solve-for parameters by the Russian astronomer E.V. Pitjeva by fitting almost one century of data with the EPM2004 ephemerides, in order to constrain some long-range models of modified gravity recently put forth to address the dark energy and dark matter problems. The models examined here are the four-dimensional ones obtained with the addition of inverse powers and logarithm of some curvature invariants, and the multidimensional braneworld model by Dvali, Gabadadze and Porrati (DGP). After working out the analytical expressions of the secular perihelion precessions induced by the corrections to the Newtonian potential of such models, we compare them to the estimated corrections to the rates of perihelia by taking their ratio for different pairs of planets instead of using one perihelion at a time for each planet separately, as done so far in literature. As a result, the curvature invariants-based models are ruled out, even by re-scaling by a factor 10 the errors in the planetary orbital parameters estimated by Pitjeva. Less neat is the situation for the DGP model. Only the general relativistic Lense-Thirring effect, not included, as the other exotic models considered here, by Pitjeva in the dynamical force models used in the estimation process, passes such a test. It would be important to repeat the present analysis by using corrections to the precessions of perihelia independently estimated by other teams of astronomers as well, but, at present, such rates are not yet available.