University Of Tasmania

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Emerging spatial curvature can resolve the tension between high-redshift CMB and low-redshift distance ladder measurements of the Hubble constant

journal contribution
posted on 2023-05-21, 07:11 authored by Krzysztof BolejkoKrzysztof Bolejko
The measurements of the Hubble constant reveal a tension between high-redshift (CMB) and low-redshift (distance ladder) constraints. So far neither observational systematics nor new physics has been successfully implemented to explain away this tension. This paper presents a new solution to the Hubble constant problem. The solution is based on the Simsilun simulation (relativistic simulation of the large scale structure of the Universe) with the ray-tracing algorithm implemented. The initial conditions for the Simsilun simulation were set up as perturbations around the ΛCDM model. However, unlike in the standard cosmological model (i.e., ΛCDM model+perturbations), within the Simsilun simulation relativistic and nonlinear evolution of cosmic structures lead to the phenomenon of emerging spatial curvature, where the mean spatial curvature evolves from the spatial flatness of the early Universe towards the slightly curved present-day Universe. Consequently, the present-day expansion rate is slightly faster compared to the spatially flat ΛCDM model. The results of the ray-tracing analysis show that the Universe which starts with initial conditions consistent with the Planck constraints should have the Hubble constant H0=72.5±2.1 km s-1 Mpc-1. When the Simsilun simulation was rerun with no inhomogeneities imposed, the Hubble constant inferred within such a homogeneous simulation was H0=68.1±2.0 km s-1 Mpc-1. Thus, the inclusion of nonlinear relativistic evolution that leads to the emergence of the spatial curvature can explain why the low-redshift measurements favor higher values compared to the high-redshift constraints and alleviate the tension between the CMB and distance ladder measurements of the Hubble constant.


Australian Research Council


Publication title

Physical Review D



Article number









School of Natural Sciences


American Physical Society

Place of publication

United States

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Copyright 2018 American Physical Society

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