Baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI) show evidence of a deviation from a cosmological constant within a Bayesian analysis. In this work, we validate that frequentist constraints from profile likelihoods on the Chevallier-Polarski-Linder parameters w₀, wₐ 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 ² from the individual datasets. For profile likelihoods of the matter fraction ₘ, such an investigation shows internal inconsistencies when assuming, which are resolved when assuming a w₀wₐ 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. Thus our frequentist analysis corroborates previous findings on dynamical DE.
Herold et al. (Fri,) studied this question.
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