DESIgning concordant distances in the age of precision cosmology: the impact of density fluctuations

Abstract

Discrepancies between distance measurements and $\Lambda$CDM predictions reveal notable features in the distance-redshift relation, possibly suggesting the presence of an evolving dark energy component. Given the central role of the Friedmann-Lemaître-Robertson-Walker (FLRW) metric in modeling cosmological distances, we investigate here whether these features instead point to a possible departure from the fundamental FLRW symmetries. Exploiting the transverse and line-of-sight distances provided by baryonic acoustic oscillations (BAO) observations, we demonstrate that observed distances hint at a slight but systematic preference for an anisotropic expansion rate emerging regardless of the dark energy model considered. Leveraging this non-FLRW feature, we investigate an inhomogeneous extension of the $\Lambda$CDM model that naturally provides an anisotropic expansion rate. Our analysis demonstrates that models featuring spherical overdensities can explain BAO, supernova, and cosmic microwave background data, providing fits statistically indistinguishable from those obtained with a phantom dark energy scenario. When Pantheon+ data is considered, our analysis challenges the FLRW framework at $2.8\sigma$ and yields scenarios that can be interpreted as subtle but non-negligible deviations from the FLRW metric. When DESY5 supernovae are considered instead, deviations are notably more significant, yielding scenarios that mildly violate the Copernican principle and exclude the FLRW assumption at $5.2\sigma$. Overall, our results motivate a more in-depth investigation of whether the perfectly homogeneous and isotropic FLRW paradigm can still be assumed to accurately predict cosmological distances in the era of precision cosmology.

14 pages + references, 5 figures, 1 table, v2 reflects version accepted for publication in PRD

References in corpus (42)

• DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
• Confronting Lemaitre-Tolman-Bondi models with Observational Cosmology
• Lemaitre-Tolman-Bondi model and accelerating expansion
• The Local Perspective on the Hubble Tension: Local Structure Does Not Impact Measurement of the Hubble Constant
• CMB anisotropies seen by an off-center observer in a spherically symmetric inhomogeneous universe
• A covariant approach for perturbations of rotationally symmetric spacetimes
• Living in a Void: Testing the Copernican Principle with Distant Supernovae
• Interpreting DESI's evidence for evolving dark energy
• Scant evidence for thawing quintessence
• Testing the Void against Cosmological data: fitting CMB, BAO, SN and H0
• Can we avoid dark energy?
• Precision cosmology defeats void models for acceleration
• Scalar Perturbations on Lemaitre-Tolman-Bondi Spacetimes
• Interpreting DESI 2024 BAO: late-time dynamical dark energy or a local effect?
• Mapping Luminosity-Redshift Relationship to LTB Cosmology
• New constraints on interacting dark energy from DESI DR2 BAO observations
• Challenging $\Lambda$CDM: 5$\sigma$ Evidence for a Dynamical Dark Energy Late-Time Transition
• Assessing cosmological evidence for non-minimal coupling
• The radial BAO scale and Cosmic Shear, a new observable for Inhomogeneous Cosmologies
• Linear kinetic Sunyaev-Zel'dovich effect and void models for acceleration
• Observational constraints on the LLTB model
• Pressure Parametrization of Dark Energy: First and Second-Order Constraints with Latest Cosmological Data
• A simultaneous solution to the Hubble tension and observed bulk flow within 250 $h^{-1}$ Mpc
• CMB constraints on the early universe independent of late time cosmology
• Probing spatial homogeneity with LTB models: a detailed discussion
• An effective description of Laniakea: impact on cosmology and the local determination of the Hubble constant
• Physical vs phantom dark energy after DESI: thawing quintessence in a curved background
• Dynamical Dark Energy Implies a Coupled Dark Sector: Insights from DESI DR2 via a Data-Driven Approach
• Optimal Reconstruction of Baryon Acoustic Oscillations for DESI 2024
• Exploring non-cold dark matter in a scenario of dynamical dark energy with DESI DR2 data
• Supernovae evidence for foundational change to cosmological models
• Evolving Dark Energy or Evolving Dark Matter?
• Covariant cosmography: the observer-dependence of the Hubble parameter
• Cosmological foundations revisited with Pantheon+
• Improved null tests of $\Lambda$CDM and FLRW in light of DESI DR2
• Constraints on an Anisotropic Universe
• Spatial and temporal tuning in void models for acceleration
• Bayesian analysis of a Unified Dark Matter model with transition: can it alleviate the $H_0$ tension?
• Growth of power spectrum due to decrease of sound speed during inflation
• Towards Cosmography of the Local Universe
• A novel approach to cosmological non-linearities as an effective fluid
• Alleviating the Hubble Tension with a Local Void and Transitions of the Absolute Magnitude

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