Parameterizing the Deceleration Parameter

TL;DR

This paper introduces three well-behaved, model-independent parameterizations of the deceleration parameter, constrained by recent observational data, valid from the matter era to the far future, without divergence at any redshift.

Contribution

It proposes and constrains three new parameterizations of the deceleration parameter that are valid across cosmic history and do not diverge, based solely on the assumption of large-scale homogeneity and isotropy.

Findings

Three parameterizations are consistent with observational data.

The models remain well-behaved across all redshifts.

They are independent of specific cosmological models.

Abstract

We propose and constrain with the latest observational data three parameterizations of the deceleration parameter, valid from the matter era to the far future. They are well behaved and do not diverge at any redshift. On the other hand, they are model independent in the sense that in constructing them the only assumption made was that the Universe is homogeneous and isotropic at large scales.