A Forecast for Large Scale Structure Constraints on Horndeski Gravity with Line Intensity Mapping

TL;DR

This paper forecasts the potential of line intensity mapping of CO transitions to detect deviations from General Relativity within Horndeski gravity models, emphasizing the need for extensive spectrometer hours and the feasibility of future experiments.

Contribution

It introduces a forecast method for using line intensity mapping to constrain Horndeski gravity parameters, highlighting the experimental requirements and potential scientific impact.

Findings

A mm-wave LIM experiment can constrain key Horndeski parameters to 0.1 accuracy.

Detecting deviations from GR is feasible with 10^8-10^9 spectrometer hours in the 2030s.

The modeling code used is publicly available.

Abstract

We consider the potential for line intensity mapping (LIM) of the rotational CO(1-0), CO(2-1) and CO(3-2) transitions to detect deviations from General Relativity from $0 < z < 3$ within the framework of a very general class of modified gravity models, called Horndeski theories. Our forecast assumes a multi-tracer analysis separately obtaining information from the matter power spectrum and the first two multipoles of the redshift space distortion power spectrum. To achieve $\pm 0.1$ level constraints on the slope of the kinetic gravity braiding and Planck mass evolution parameters, a mm-wave LIM experiment would need to accumulate $\approx 10^8-10^9$ spectrometer hours, feasible with instruments that could be deployed in the 2030s. Such a measurement would constrain large portions of the remaining parameter space available to Scalar-Tensor modified gravity theories. Our modeling code is publicly available.