Evidence for cosmic acceleration with next-generation surveys: A model-independent approach

TL;DR

This study uses simulated next-generation surveys to non-parametrically confirm cosmic acceleration with high confidence, independent of dark energy models, significantly surpassing current measurement capabilities.

Contribution

It introduces a model-independent, Gaussian Processes-based method to reconstruct the deceleration parameter from simulated survey data, demonstrating strong evidence for cosmic acceleration.

Findings

Euclid-like surveys can detect acceleration at over 3σ

SKA-like surveys can detect acceleration at over 5σ

Combined surveys increase confidence to over 7σ

Abstract

We quantify the evidence for cosmic acceleration using simulations of $H(z)$ measurements from SKA- and Euclid-like surveys. We perform a non-parametric reconstruction of the Hubble parameters and its derivative to obtain the deceleration parameter $q(z)$ using the Gaussian Processes method. This is a completely model-independent approach, so we can determine whether the Universe is undergoing accelerated expansion {\it regardless} of any assumption of a dark energy model. We find that Euclid-like and SKA-like band 1 surveys can probe cosmic acceleration at over $3$ and $5\sigma$ confidence level, respectively. By combining them with a SKA-like band 2 survey, which reaches lower redshift ranges, the evidence for a current accelerated phase increases to over $7\sigma$. This is a significant improvement from current $H(z)$ measurements from cosmic chronometers and galaxy redshift surveys, showing that these surveys can underpin cosmic acceleration in a model-independent way.