Cosmological Tests of General Relativity with Future Tomographic Surveys

TL;DR

Future tomographic surveys will enable precise tests of general relativity on cosmic scales by analyzing matter perturbations and gravitational potentials, allowing for model-independent constraints on deviations from Einstein's theory.

Contribution

Introduces two functions to describe modifications to gravity in the linear regime and uses principal component analysis to forecast constraints from upcoming surveys.

Findings

Multiple eigenmodes of deviations can be constrained by data.

Scale and time dependence of modes inform which models are testable.

Forecasts the number of parameters that future surveys can constrain.

Abstract

Future weak lensing surveys will map the evolution of matter perturbations and gravitational potentials, yielding a new test of general relativity on cosmic scales. They will probe the relations between matter overdensities, local curvature, and the Newtonian potential. These relations can be modified in alternative gravity theories or by the effects of massive neutrinos or exotic dark energy fluids. We introduce two functions of time and scale which account for any such modifications in the linear regime. We use a principal component analysis to find the eigenmodes of these functions that cosmological data will constrain. The number of constrained modes gives a model-independent forecast of how many parameters describing deviations from general relativity could be constrained, along with $w(z)$. The modes' scale and time dependence tell us which theoretical models will be better tested.