Inferring dark energy properties from the scale factor parametrisation

TL;DR

This paper introduces a new method to test deviations from the standard cosmological model by analyzing the scale factor to infer dark energy properties, focusing on the validity of the cosmological constant.

Contribution

It presents a novel test based on the scale factor to assess dark energy models, avoiding common parametric assumptions and constraining the EoS to physically viable regions.

Findings

Dark energy EoS constrained to quintessence-like behavior

Excludes phantom crossings and exponential growth regions

Supports the cosmological constant as a valid model

Abstract

We propose and implement a novel test to assess deviations from well-established concordance $\Lambda$CDM cosmology while inferring dark energy properties. In contrast to the commonly implemented parametric forms of the dark energy equation-of-state (EoS), we test the validity of the cosmological constant on the more fundamental scale factor [$a(t)$] which determines the expansion rate of the Universe. We constrain our extended `general model' using the late-time observables. The posterior of the dark energy EoS is mainly constrained to be quintessence-like naturally excluding physically unviable regions such as phantom crossings or exponential growth.