Dynamical dark energy parameterizations in VCDM

TL;DR

This paper demonstrates how VCDM, a minimally modified gravity theory, can realize various dark energy parameterizations and tests them against recent cosmological data, offering a consistent framework for dynamical dark energy models.

Contribution

It introduces VCDM realizations of popular dark energy parameterizations and tests their observational viability using recent cosmological datasets.

Findings

VCDM can reproduce various dark energy behaviors without instabilities.

Certain parameterizations fit the Planck 2018 and DESI BAO DR2 data well.

The framework allows for consistent testing of dynamical dark energy models.

Abstract

In the context of a theory of minimally modified gravity called VCDM, one can realize any cosmological behavior at the level of the homogeneous and isotropic background without introducing fatal instabilities for perturbations. Therefore, VCDM provides a theoretically-consistent and observationally-testable framework of dynamical dark energy parameterizations with or without phantom behaviors. In this paper, we propose the VCDM realizations of various phenomenological parameterizations present in the literature: the Chevallier-Polarski-Linder (CPL), Barboza-Alcaniz (BA), Jassal-Bagla-Padmanabhan (JBP), Exponential (EXP), and Logarithmic (LOG) models. Using the VCDM equations for cosmological perturbations, we test them against the recent cosmological datasets, Planck 2018 and DESI BAO DR2, and then discuss their implications.