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Stringent constraint on the CCC+TL cosmology with $H(z)$ Measurements

Lei Lei, Ze-Fan Wang, Tong-Lin Wang, Yi-Ying Wang, Guan-Wen Yuan, Wei-Long Lin, Yi-Zhong Fan

Abstract

Recently, the Covarying Coupling Constants and Tired Light (CCC+TL) hybrid model was proposed to explain the unexpectedly small angular diameters of high-redshift galaxies observed by the James Webb Space Telescope (JWST) that are challenging to reconcile with the $Λ$CDM model. In this work, we test the CCC+TL model against model-independent Hubble parameter [$H(z)$] measurements obtained from cosmic chronometers. It turns out that the parameter set optimized for the type-Ia supernova (SN Ia) dataset within the CCC+TL model fails to reproduce the $H(z)$ data, but the $Λ$CDM model works well. Statistical comparison using the $Δχ^2$ strongly favors $Λ$CDM over CCC+TL for the $H(z)$ data, with $Δχ^2 = 61.52$. Crucially, the CCC+TL framework exhibits a severe internal tension, where the SN Ia-optimized speed-of-light variation index $α$ is rejected by the $H(z)$ dataset with a likelihood ratio of $\mathcal{R} \approx 1.7 \times 10^{-14}$. Our result suggests that the tension posed by JWST observations of compact high-$z$ galaxies may originate from the intrinsic properties and evolution of galaxies in the early universe.

Stringent constraint on the CCC+TL cosmology with $H(z)$ Measurements

Abstract

Recently, the Covarying Coupling Constants and Tired Light (CCC+TL) hybrid model was proposed to explain the unexpectedly small angular diameters of high-redshift galaxies observed by the James Webb Space Telescope (JWST) that are challenging to reconcile with the CDM model. In this work, we test the CCC+TL model against model-independent Hubble parameter [] measurements obtained from cosmic chronometers. It turns out that the parameter set optimized for the type-Ia supernova (SN Ia) dataset within the CCC+TL model fails to reproduce the data, but the CDM model works well. Statistical comparison using the strongly favors CDM over CCC+TL for the data, with . Crucially, the CCC+TL framework exhibits a severe internal tension, where the SN Ia-optimized speed-of-light variation index is rejected by the dataset with a likelihood ratio of . Our result suggests that the tension posed by JWST observations of compact high- galaxies may originate from the intrinsic properties and evolution of galaxies in the early universe.

Paper Structure

This paper contains 5 sections, 9 equations, 4 figures, 2 tables.

Table of Contents

  1. Introduction
  2. CCC+TL Hybrid Model
  3. Data and Analysis
  4. Results
  5. Conclusion and Discussion

Figures (4)

  • Figure 1: The red and blue solid lines show the best fits of the CCC+TL and $\Lambda$CDM models, respectively, to the $H(z)$ data. The color regions represent the $1\sigma$ uncertainties. The red dash-dotted line is the "predicted $H(z)$" with the CCC+TL best-fit parameters of 2023MNRAS.524.3385G, which significantly deviates from the observation data (the black error bar points).
  • Figure 2: Redshift contributions of the CCC and TL components within the CCC+TL model, calculated using the best-fit SNe Ia parameters. Left Panel: Ratio of the TL redshift contribution to the CCC contribution (red) and to the total redshift $z_{\rm{CCC+TL}}$ (black). Right Panel: Proportion of the total redshift $z_{\rm{CCC+TL}}$ attributed to the CCC (red) and TL (blue) components.
  • Figure 3: Posterior distributions of parameters for the CCC+TL (Left Panel) and $\Lambda$CDM (Right Panel) models obtained from fitting the $H(z)$ dataset.
  • Figure 4: The variation function of the speed of light ($f(z)=c/c_0$) within the CCC+TL model. The red dash-dotted and solid lines correspond to the best-fit results for the SNe Ia 2023MNRAS.524.3385G and $H(z)$ datasets, respectively. The orange region is the 68% range fitted with $H(z)$ dataset.