Will Multiple Probes of Dark Energy find Modified Gravity?

TL;DR

This paper evaluates the effectiveness of multiple dark energy probes in detecting deviations from general relativity, proposing a new multi-dimensional consistency test to improve the identification of modified gravity models.

Contribution

It introduces a novel multi-dimensional consistency test and methodology for projecting its effectiveness in distinguishing modified gravity from GR using upcoming dark energy experiments.

Findings

Standard overlap tests have limitations in detecting modified gravity.

The proposed multi-dimensional test offers increased power in consistency checks.

Methodology enables forecasting experiment capabilities to identify deviations from GR.

Abstract

One of the most pressing issues in cosmology is whether general relativity (GR) plus a dark sector is the underlying physical theory or whether a modified gravity model is needed. Upcoming dark energy experiments designed to probe dark energy with multiple methods can address this question by comparing the results of the different methods in constraining dark energy parameters. Disagreement would signal the breakdown of the assumed model (GR plus dark energy). We study the power of this consistency test by projecting constraints in the $w_0-w_a$ plane from the four different techniques of the Dark Energy Survey in the event that the underlying true model is modified gravity. We find that the standard technique of looking for overlap has some shortcomings, and we propose an alternative, more powerful Multi-dimensional Consistency Test. We introduce the methodology for projecting whether a given experiment will be able to use this test to distinguish a modified gravity model from GR.