Cosmographic approach to Running Vacuum dark energy models: new constraints using BAOs and Hubble diagrams at higher redshifts

TL;DR

This study evaluates various dark energy models, especially Running Vacuum models, using high-redshift cosmographic data and BAOs, finding RVMs to be the most favored and capable of alleviating key cosmological tensions.

Contribution

It introduces a cosmographic analysis of Running Vacuum models with new constraints from high-redshift data, demonstrating their viability and superiority over other dark energy models.

Findings

RVMs are favored over GDEs when BAO data are included.

Without BAOs, models show tensions at high redshifts.

RVMs help alleviate $\sigma_8$ and $H_0$ tensions.

Abstract

In this work we study different types of dark energy (DE) models in the framework of the cosmographic approach, with emphasis on the Running Vacuum models (RVMs). We assess their viability using different information criteria and compare them with the so-called Ghost DE models (GDEs) as well as with the concordance $\Lambda$CDM model. We use the Hubble diagrams for Pantheon SnIa, quasars (QSOs), gamma-ray bursts (GRBs) as well as the data on baryonic acoustic oscillations (BAOs) in four different combinations. Upon minimizing the $\chi^2$ function of the distance modulus in the context of the Markov Chain Monte Carlo method (MCMC), we put constraints on the current values of the standard cosmographic parameters in a model-independent way. It turns out that, in the absence of BAOs data, the various DE models generally exhibit cosmographic tensions with the observations at the highest redshifts (namely with the QSOs and GRBs data). However, if we include the robust observations from BAOs to our cosmographic sample, the $\Lambda$CDM and RVMs are clearly favored against the GDEs. Finally, judging from the perspective of the deviance information criterion (DIC), which enables us to compare models making use of the Markov chains of the MCMC method, we conclude that the RVMs are the preferred kind of DE models. We find it remarkable that these models, which had been previously shown to be capable of alleviating the $\sigma_8$ and $H_0$ tensions, appear now also as the most successful ones at the level of the cosmographic analysis.