Bayesian and frequentist perspectives agree on dynamical dark energy

Abstract

Baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI) show evidence of a deviation from a cosmological constant $\hat{I}›$ within a Bayesian analysis. In this work, we validate that frequentist constraints from profile likelihoods on the Chevallier-Polarski-Linder parameters $w_0$, $w_a$ 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 $\ddot{I}{‡}^2$ from the individual datasets. For profile likelihoods of the matter fraction $\hat{I}{\text{c◯}}_{\mathrm{m}}$, such an investigation shows internal inconsistencies when assuming $\hat{I}›$, which are resolved when assuming a $w_0{w}_a$ 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 $\hat{I}›$. Thus our frequentist analysis corroborates previous findings on dynamical DE.

13 pages, 8 figures; updated to match version published in PRD

References in corpus (2)

• Cosmology in Extended Parameter Space with DESI Data Release 2 Baryon Acoustic Oscillations: A 2$\ddot{I}ƒ$+ Detection of Nonzero Neutrino Masses with an Update on Dynamical Dark Energy and Lensing Anomaly
• The Dark Energy Survey Supernova Program: A Reanalysis Of Cosmology Results And Evidence For Evolving Dark Energy With An Updated Type Ia Supernova Calibration

Cited by in corpus (1)

• Modifying $\hat{I}›$CDM dynamics via out-of-equilibrium axions: reconciling SH0ES and DESI $H_0$ values