A proposal to improve the accuracy of cosmological observables and address the Hubble tension problem

Abstract

(abridged)Cosmological observational programs often compare their data not only with $\Lambda$CDM, but also with extensions applying dynamical models of dark energy (DDE), with a time-dependent equation of state (EoS) parameter $w$. We found a degeneracy in the customary computational procedure for the expansion history, once DDE models are applied. This degeneracy provides an infinite number of cosmological models reproducing the Planck-measured CMB spectrum. Moreover, this degeneracy biases the comparison of $\Lambda$CDM with DDE extensions. We present a complementary computational approach, which breaks this degeneracy: the ``fixed early densities (EDs) approach'' evolves cosmological models from the early Universe to the present, in contrast to the customary ``fixed $H_0$ approach'' which evolves cosmological models in reverse order. We find the EDs are accurately approximated by the $\Lambda$CDM model. We implement a refined procedure, appyling both approaches, in an amended version of the code CLASS, where we focus on representative DDE models using the CPL parametrization. Our results reveal that the CPL model $w(a)=-0.9+0.1(1-a)$ could provide a resolution to the Hubble tension problem. Moreover, we find that combining both approaches, while requesting to yield consistent results and being in agreement with observations across cosmic time, can serve as a kind of consistency check for cosmological models. Moreover, our proposed consistency check applied within current data analysis methods will increase the accuracy of inferred cosmological parameters significantly, in particular for $\Lambda$CDM extensions. We find characteristic signatures in the late expansion histories of cosmological models, allowing a phenomenological discrimination of DE candidates and a possible resolution of the Hubble tension, by ongoing and future observational programs.

submitted to A&A, 21 pages, 12 figures, published online 12 June 2024

References in corpus (21)

• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team
• In the Realm of the Hubble tension $-$ a Review of Solutions
• Dark Energy Survey Year 3 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing
• Supernova Constraints and Systematic Uncertainties from the First 3 Years of the Supernova Legacy Survey
• The trouble with $H_0$
• SNLS3: Constraints on Dark Energy Combining the Supernova Legacy Survey Three Year Data with Other Probes
• On the Hubble constant tension in the SNe Ia Pantheon sample
• Seven hints that early-time new physics alone is not sufficient to solve the Hubble tension
• On the evolution of the Hubble constant with the SNe Ia Pantheon Sample and Baryon Acoustic Oscillations: a feasibility study for GRB-cosmology in 2030
• The Local Perspective on the Hubble Tension: Local Structure Does Not Impact Measurement of the Hubble Constant
• The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) Survey Design, Reductions, and Detections
• Dark Energy Survey Year 3 Results: A 2.7% measurement of Baryon Acoustic Oscillation distance scale at redshift 0.835
• Can dark energy be dynamical?
• The Gamma-ray Bursts fundamental plane correlation as a cosmological tool
• Gamma-Ray Bursts, Quasars, Baryonic Acoustic Oscillations, and Supernovae Ia: new statistical insights and cosmological constraints
• Reducing the uncertainty on the Hubble constant up to 35\% with an improved statistical analysis: different best-fit likelihoods for Supernovae Ia, Baryon Acoustic Oscillations, Quasars, and Gamma-Ray Bursts
• Constraining the dark energy models using Baryon Acoustic Oscillations: An approach independent of $H_0\cdot r_d$
• Cosmic expansion parametrization: Implication for curvature and ${\text{H}}_0$ tension
• Tensions with the flat $\mathbf{\Lambda }$CDM model from high-redshift cosmography
• Early dark energy constraints with late-time expansion marginalization
• Solving the Hubble tension à la Ellis & Stoeger 1987

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• On the True Significance of the Hubble Tension: A Bayesian Error Decomposition Accounting for Information Loss