Bayesian and frequentist perspectives agree on dynamical dark energy

2025/06/13 by Herold, Laura, Karwal, Tanvi · 12 citations
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences

paper · doi:10.48550/arxiv.2506.12004

Abstract

Baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI) show evidence of a deviation from a cosmological constant Λ within a Bayesian analysis. In this work, we validate that frequentist constraints from profile likelihoods on the Chevallier-Polarski-Linder parameters w₀, w_a are in excellent agreement with the Bayesian constraints when combining with Planck cosmic microwave background, Planck and Atacama Cosmology Telescope lensing, and either Pantheon+ or Dark Energy Survey Y5 supernova data. Further, we assess which datasets drive these constraints by considering the contributions to the χ² from the individual datasets. For profile likelihoods of the matter fraction Ω_m, such an investigation shows internal inconsistencies when assuming Λ, which are resolved when assuming a w₀w_a dark-energy model. We infer the equations of state w(z) at the pivot redshifts, supporting previous interpretations that current data appears to be more sensitive to the derivative of w(z) rather than a mean offset from Λ. Thus our frequentist analysis corroborates previous findings on dynamical DE.

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• Cosmological constraints on nonphantom dynamical dark energy with DESI Data Release 2 Baryon Acoustic Oscillations: A 3σ+ lensing anomaly
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