Chameleon gravity and satellite geodesy

Tests of chameleon gravity

Theories of modified gravity, where light scalars with non-trivial self-interactions and non-minimal couplings to matter-chameleon and symmetron theories-dynamically suppress deviations from general relativity in the solar system. On other scales, the environmental nature of the screening means that such scalars may be relevant. The highly-nonlinear nature of screening mechanisms means that the...

Reference Systems in Satellite Geodesy

An Introduction to Chameleon Gravity

Following work by Khoury and Weltman, we introduce a scalar field φ, the chameleon, which is conformally coupled to matter. That is, matter experiences a metric which is a conformal transform (parametrized by φ) of the Einstein metric. The effective potential of the field φ is a sum of its selfinteraction term and an exponential term due to the conformal coupling. Under certain conditions on th...

Chameleon Halo Modeling in f(R) Gravity

We model the chameleon effect on cosmological statistics for the modified gravity f(R) model of cosmic acceleration. The chameleon effect, required to make the model compatible with local tests of gravity, reduces force enhancement as a function of the depth of the gravitational potential wells of collapsed structure and so is readily incorporated into a halo model by including parameters for t...

Local Geodesy by Satellite Laser Ranging: a European Solution

Errors in the modelling the satellite orbit have so far limited the accuracy in the processing of Satellite Laser Ranging (SLR) data. A new method is proposed to achieve a residual size consistent with the observational errors, and a stability of the geode-tic network coordinates at the same level. The orbit of the geodetic satellite LAGEOS is decomposed into very short arcs (less than half orb...