A derived evolution of dark energy from cosmic inhomogeneity confronted with baryon acoustic oscillations and type Ia supernovae
Year: 2026
Type: preprint
Abstract: The volume dynamics of space is a framework in which the possibility that matter can be unevenly distributed enters the expansion dynamics directly. It yields a redshift-dependent effective Hubble constant and dark-energy density parameter from the Planck parameters alone. We derive the expansion history $H(z)$ of the framework and show that it is flat $Λ$CDM with the cosmological constant replaced by a dark-energy density that grows by 31 percent toward the present, with an effective equation of state $w(0) = -1.21$ approaching $-1$ at high redshift and a present-day age of 13.52 Gyr, 0.3 Gyr younger than in the homogeneous limit. We confront it with the DESI DR2 baryon acoustic oscillations and the Pantheon+ type Ia supernovae, with the Hubble constant, the sound horizon and the supernova absolute magnitude free, so that only the shape of $H(z)$ is tested. Relative to $Λ$CDM the prediction is disfavored by $Δχ^2 = 65$ with one parameter fewer. A free matter density reduces this to $Δχ^2 = 42$, because each probe alone accommodates the model only with incompatible matter densities (0.35 from the oscillations, 0.54 from the supernovae). Their combination bounds the heterogeneity amplitude to $σ_8 < 0.14$ at 95 percent confidence, against the Planck input 0.81; the best fit of the heterogeneous model is its homogeneous limit, flat $Λ$CDM. At the leading order currently evaluated, the heterogeneous contribution cannot account for the Hubble tension, and it acts opposite to the evolution of dark energy that current distance data favor.
Source: arXiv (Cornell University)
Authors: Yang, Jacky David, Carmesin, Hans-Otto
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214596750