Model Independent Tests of Cosmic Gravity

TL;DR

This paper proposes a model-independent framework to test deviations from general relativity on cosmic scales, aiming to identify potential signs of alternative gravity theories through future observational data.

Contribution

It introduces a classification scheme for deviations from Einstein's gravity and establishes criteria for future surveys to detect these deviations with required precision.

Findings

Developed a phase space analysis of post-GR functions

Derived an absolute accuracy criterion for distinguishing gravity models

Forecasted future survey capabilities to constrain deviations

Abstract

Gravitation governs the expansion and fate of the universe, and the growth of large scale structure within it, but has not been tested in detail on these cosmic scales. The observed acceleration of the expansion may provide signs of gravitational laws beyond general relativity. Since the form of any such extension is not clear, from either theory or data, we adopt a model independent approach to parametrising deviations to the Einstein framework. We explore the phase space dynamics of two key post-GR functions and derive a classification scheme and an absolute criterion on accuracy necessary for distinguishing classes of gravity models. Future surveys will be able to constrain the post-GR functions' amplitudes and forms to the required precision, and hence reveal new aspects of gravitation.