Tests of modified gravity theories in the Solar System

Abstract

We review the case for testing preferred acceleration scale theories of gravity (sometimes falling under the guise of MOdified Newtonian Dynamics) in the Solar System using the forthcoming LISA Pathfinder (LPF) mission. Using a combination of analytical and numerical results, we suggest that different types of theory should be detectable using the predicted anomalous tidal stresses effects around the saddle points of the Newtonian gravitational field. The saddle point bubbles expected extent of ∼ 400 km are to be contrasted with potential miss parameters of ≤ 10 km, making such a test in easy reach of LPF. We also consider routes to constraining our theories from data, based on scenarios of both null and positive results.

Screening Solutions in Modified Gravity Theories

“…In this short letter we aim to show that chameleonesque screening mechanisms are naturally present in preferred acceleration modified gravity theories. As such they are of significant interest if we are looking to hide additional effects on Solar System scales and also tests of these modified theories should reach the level of potentially certifying or vilifying models and classes of theories in the very near future [1]. The use of the forthcoming LISA Pathfinder mission [2] provides an opportunity to directly probe an unexplored low acceleration regime as well, as well as test some less conventional ideas in gravitational physics [3,4].…”