Baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument show evidence of a deviation from a cosmological constant $\mathrm{\Lambda }$ 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 $\mathrm{Pantheon}+$ or Dark Energy Survey Year 5 supernova data. Further, we assess which datasets drive these constraints by considering the contributions to the ${\chi }^2$ from the individual datasets. For profile likelihoods of the matter fraction ${\mathrm{\Omega }}_{\mathrm{m}}$, such an investigation shows internal inconsistencies when assuming $\mathrm{\Lambda }$, 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 appear to be more sensitive to the derivative of $w(z)$ rather than a mean offset from $\mathrm{\Lambda }$. Thus, our frequentist analysis corroborates previous findings on dynamical dark energy.

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• Baryon acoustic oscillations
• Cosmic microwave background
• Cosmological parameters
• Dark energy