New analysis of SNeIa Pantheon Catalog: Variable speed of light as an alternative to dark energy

Abstract

In A&A 412, 35 (2003) Blanchard, Douspis, Rowan-Robinson, and Sarkar (BDRS) slightly modified the primordial fluctuation spectrum and produced an excellent fit to WMAP's CMB power spectrum for an Einstein-de Sitter (EdS) universe, bypassing dark energy. Curiously, they obtained a Hubble value of $H_0\approx 46$, in sharp conflict with the canonical range $H_0\sim 67-73$. However, we will demonstrate that the reduced value of $H_0\approx 46$ achieved by BDRS is fully compatible with the use of variable speed of light in analyzing the late-time cosmic acceleration observed in Type Ia supernovae (SNeIa). In Phys. Lett. B 862, 139357 (2025) we uncovered a hidden aspect in a generic class of scale-invariant actions: the dynamics of the dilaton can induce a variation in the speed of light as $c\propto {\chi }^{1/2}$, causing $c$ to vary alongside $\chi$ across spacetime. For an EdS universe with varying $c$, besides the effects of cosmic expansion, light waves emitted from distant SNeIa are further subject to a refraction effect, which alters the Lemaitre redshift relation to $1+z=a^{-3/2}$. Based on this new formula, we achieve a fit to the SNeIa Pantheon Catalog exceeding the quality of the $\Lambda$CDM model. Crucially, our approach does not require dark energy and produces $H_0=47.2$ in strong alignment with the BDRS finding of $H_0\approx 46$. Hence, BDRS's analysis of the (early-time) CMB power spectrum and our variable-$c$ analysis of the (late-time) Hubble diagram of SNeIa fully agree on two counts: (i) the dark energy hypothesis is avoided, and (ii) $H_0$ is reduced to $\sim 47$, which also yields an age $t_0=2/(3H_0)=13.8$ Gy for an EdS universe, without requiring dark energy. Most importantly, we will demonstrate that the late-time acceleration can be attributed to the declining speed of light in an expanding EdS universe, rather than to a dark energy component.

Final version. Published in JCAP

References in corpus (37)

• Cosmology and the Fate of Dilatation Symmetry
• In the Realm of the Hubble tension $-$ a Review of Solutions
• Challenges for $\Lambda$CDM: An update
• On the Hubble constant tension in the SNe Ia Pantheon sample
• Running Hubble Tension and a H0 Diagnostic
• The status of varying constants: a review of the physics, searches and implications
• EPOCHS VI: The Size and Shape Evolution of Galaxies since z ~ 8 with JWST Observations
• Light speed variation from gamma-ray bursts
• Light speed variation from gamma ray burst GRB 160509A
• No fifth force in a scale invariant universe
• Note on Varying Speed of Light Cosmologies
• Model-Independent Constraints on Lorentz Invariance Violation via the Cosmographic Approach
• The minimally extended Varying Speed of Light (meVSL)
• Model-independent constraints on Lorentz invariance violation: implication from updated Gamma-ray burst observations
• Measuring the speed of light with Baryon Acoustic Oscillations
• Pre-burst events of gamma-ray bursts with light speed variation
• Cosmology with relativistically varying physical constants
• Observational constraint on the varying speed of light theory
• Comments on "Note on varying speed of light theories"
• A search for the variation of speed of light using galaxy cluster gas mass fraction measurements
• Search for Lorentz Invariance Violation from stacked Gamma-Ray Burst spectral lag data
• Consistency testing for invariance of the speed of light at different redshifts: the newest results from strong lensing and type Ia supernovae observations
• Variation of the speed of light and a minimum speed in the scenario of an inflationary universe with accelerated expansion
• Constraining minimally extended varying speed of light by cosmological chronometers
• Testing a varying-$\Lambda$ model for dark energy within Co-varying Physical Couplings framework
• Constraint on the minimally extended varying speed of light using time dilations in type Ia supernovae
• Varying physical constants and the lithium problem
• Measuring the speed of light with updated Hubble diagram of high-redshift standard candles
• Constraining a possible time-variation of the speed of light along with the fine-structure constant using strong gravitational lensing and Type Ia supernovae observations
• SNe Data Analysis in Variable Speed of Light Cosmologies without Cosmological Constant
• Shadows of black holes at cosmological distances in the co-varying physical couplings framework
• On the time variation of c, G, and h and the dynamics of the cosmic expansion
• Examining the validity of the minimal varying speed of light model through cosmological observations: relaxing the null curvature constraint
• Measuring the speed of light with cosmological observations: current constraints and forecasts
• Constraints on the time variation of the speed of light using Strong lensing
• Dilaton-induced variations in Planck constant and speed of light: An alternative to Dark Energy
• Strong size evolution of disc galaxies since z = 1: Readdressing galaxy growth using a physically motivated size indicator

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