Constraining Cosmic Expansion and Gravity with Galaxy Redshift Surveys

TL;DR

This paper evaluates how future galaxy redshift surveys can simultaneously constrain dynamic dark energy and modified gravity models, improving understanding of cosmic expansion and gravity.

Contribution

It demonstrates that combining galaxy surveys with other data can tightly constrain model-independent modifications to gravity and dark energy without bias.

Findings

Achieves 5-10% constraints on modified gravity parameters.

Self-calibration of galaxy bias minimally impacts results.

Combining multiple data sources enhances constraints.

Abstract

We analyze the science reach of a next generation galaxy redshift survey such as BigBOSS to fit simultaneously for time varying dark energy equation of state and time- and scale-dependent gravity. The simultaneous fit avoids potential bias from assuming $\Lambda$CDM expansion or general relativity and leads to only modest degradation in constraints. Galaxy bias, fit freely in redshift bins, is self calibrated by spectroscopic measurements of redshift space distortions and causes little impact. The combination of galaxy redshift, cosmic microwave background, and supernova distance data can deliver 5-10% constraints on 6 model independent modified gravity quantities.