Probing the constancy of the speed of light with future galaxy survey: the case of SKA and Euclid

TL;DR

This paper discusses a method to test the constancy of the speed of light using galaxy surveys, specifically SKA and Euclid, by analyzing Baryon Acoustic Oscillations, and forecasts their sensitivity to detect variations.

Contribution

It provides a detailed theoretical framework and updated forecasts for using galaxy surveys to measure potential variations in the speed of light.

Findings

SKA can detect 1% variations in light speed at 3σ

Euclid and similar surveys have limited sensitivity to small variations

Guidelines for future survey sensitivity requirements

Abstract

In [1] a new method to measure the speed of light through Baryon Acoustic Oscillations (BAO) was introduced. Here, we describe in much more detail the theoretical basis of that method, its implementation, and give some newly updated results about its application to the forecast data. In particular, we will show that SKA will be able to detect a 1% variation (if any) in the speed of light at 3$\sigma$ level. Smaller signals will be hardly detected by already-planned future galaxy surveys, but we give indications about what sensitivity requirements should a survey fulfill in order to be successful.