Expansion-history preferences of DESI DR2 and external data

Abstract

We explore the origin of the preference of DESI DR2 baryon acoustic oscillation (BAO) measurements and external data from cosmic microwave background (CMB) and type Ia supernovae (SNIa) that dark energy behavior departs from that expected in the standard cosmological model with vacuum energy ($\Lambda$CDM). In our analysis, we allow a flexible scaling of the expansion rate with redshift that nevertheless allows reasonably tight constraints on the quantities of interest, and adopt and validate a simple yet accurate compression of the CMB data that allows us to constrain our phenomenological model of the expansion history. We find that data consistently show a preference for a 3-4 % increase in the expansion rate at $z\simeq 0.7$ relative to that predicted by the standard $\Lambda$CDM model, in excellent agreement with results from the less flexible $(w_0,w_a)$ parameterization which was used in previous analyses. Even though our model allows a departure from the best-fit $\Lambda$CDM model at zero redshift, we find no evidence for such a signal. We also find no evidence (at greater than 1$\sigma$ significance) for a departure of the expansion rate from the $\Lambda$CDM predictions at higher redshifts for any of the data combinations that we consider. Overall, our results strengthen the robustness of the findings using the combination of DESI, CMB, and SNIa data to dark-energy modeling assumptions.

5 pages, 2 figures, plus appendices (updated with DESI DR2 data; results qualitatively unchanged)

References in corpus (27)

• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Efficient Computation of CMB anisotropies in closed FRW models
• Exploring the Expansion History of the Universe
• Accelerating Universes with Scaling Dark Matter
• Planck 2018 results. V. CMB power spectra and likelihoods
• DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
• The Pantheon+ Analysis: The Full Dataset and Light-Curve Release
• Small Scale Cosmological Perturbations: An Analytic Approach
• Cobaya: Code for Bayesian Analysis of hierarchical physical models
• Probing the dark energy: methods and strategies
• Overview of the Instrumentation for the Dark Energy Spectroscopic Instrument
• The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters
• Observational Constraints on Dark Energy and Cosmic Curvature
• DESI 2024: Reconstructing Dark Energy using Crossing Statistics with DESI DR1 BAO data
• Interpreting DESI's evidence for evolving dark energy
• Nonparametric late-time expansion history reconstruction and implications for the Hubble tension in light of recent DESI and type Ia supernovae data
• Scant evidence for thawing quintessence
• The Pantheon+ Analysis: Evaluating Peculiar Velocity Corrections in Cosmological Analyses with Nearby Type Ia Supernovae
• Using non-DESI data to confirm and strengthen the DESI 2024 spatially-flat $w_0{w}_a$CDM cosmological parameterization result
• On using the CMB shift parameter in tests of models of dark energy
• Model-independent cosmological constraints from the CMB
• Model-agnostic assessment of dark energy after DESI DR1 BAO
• Quantifying Scalar Field Dynamics with DESI 2024 Y1 BAO measurements
• Model-independent cosmological inference post DESI DR1 BAO measurements
• CMB distance priors revisited: effects of dark energy dynamics, spatial curvature, primordial power spectrum, and neutrino parameters
• Distance Priors from \emph{Planck} 2015 data
• Testing the consistency of early and late cosmological parameters with BAO and CMB data

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