Evidence for evolving dark energy from DESI DR2 BAO and Pantheon$^+$, DES-Dovekie, and Union3

TL;DR

This study investigates evidence for evolving dark energy using recent BAO, supernova, and CMB data, finding weak to moderate support for models where dark energy changes over time, especially in the Quintom-B regime.

Contribution

It provides a comprehensive analysis of multiple dark energy parameterizations with recent observational data, highlighting dataset dependencies and the potential for evolving dark energy.

Findings

Evidence for evolving dark energy is mainly driven by LRG1-2 tracers.

Most models favor $w_0 > -1$, $w_a < 0$, indicating Quintom-B behavior.

Support for evolving dark energy is weak to moderate and dataset-dependent.

Abstract

Evidences for evolving dark energy are shown using baryon acoustic oscillation (BAO) measurements from the recent Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), combined with different Type Ia supernova datasets (Pantheon$^+$, DES-Dovekie, and Union3) and the CMB compressed likelihood. We examine several dark energy parameterizations, including the Logarithmic, Exponential, CPL, BA, JBP, Thawing, Mirage, and GEDE models. Analyzing the DESI DR2 measurements alone, we find that evidence for evolving dark energy is primarily driven by the LRG1-2 tracers, as their inclusion yields a preferred value of $w_0 > -1$. However, as each tracer provides only limited observables, this preference can result in an underconstrained and potentially unstable inference. Further, we find that each dark energy model predicts values in the $w_0 > -1$, $w_a < 0$ quadrant, a region characterized by the Quintom-B type dark energy scenario. The logarithmic Bayes factor indicates that support for evolving dark energy models is generally weak to moderate and dataset-dependent, with no model consistently outperforming $\Lambda$CDM. Finally, the evolution of $w(z)$ shows a phantom crossing around $z \sim 0.5$ in most dynamical dark energy models, and the evolution of $f_{\mathrm{DE}}(z)$ converges to $f_{\mathrm{DE}}(0) = 1$ in all dark energy models.