Contraints on unified models for dark matter and dark energy using H(z)

TL;DR

This paper uses observational H(z) data to test unified dark matter and dark energy models, specifically the GCG and viscous fluid models, assessing their viability and parameter constraints.

Contribution

It provides the first constraints on GCG and viscous fluid models using differential age H(z) data, highlighting the need for priors in GCG and parameter estimations for VF.

Findings

GCG model requires priors for a unified dark sector scenario.

VF model yields parameter estimates compatible with observational data.

Constraints help evaluate the viability of these unified models.

Abstract

The differential age data of astrophysical objects that have evolved passivelly during the history of the universe (e.g. red galaxies) allows to test theoretical cosmological models through the predicted Hubble function expressed in terms of the redshift $z$, $H(z)$. We use the observational data for $H(z)$ to test unified scenarios for dark matter and dark energy. Specifically, we focus our analysis on the Generalized Chaplygin Gas (GCG) and the viscous fluid (VF) models. For the GCG model, it is shown that the unified scenario for dark energy and dark matter requires some priors. For the VF model we obtain estimations for the free parameters that may be compared with further analysis mainly at perturbative level.