Non-Commutative fluid: an alternative source of cosmic acceleration

TL;DR

This work introduces a non-commutative (NC) Newtonian fluid cosmology in which a deformation parameter $σ$ from the NC Poisson algebra modifies the background continuity equation and yields a new Hubble function $H^2 = H_0^2 [ Ω_0/(1-σ) (1+z)^{3+σ} + (1- Ω_0/(1-σ)) (1+z)^{2σ+2} ]$, enabling late-time cosmic acceleration without dark energy. The framework predicts $ ho_0 ∝ a^{-(3+σ)}$ and constrains energy conditions such that NEC and WEC hold while SEC is violated for negative $σ$, consistent with acceleration. Observational constraints from OHD, SNeIa (Pantheon+, Union3), DESI, and DESY5 favor $σ<0$, with DESI tightening the allowed region, though the NC model generally underperforms ΛCDM in χ^2 comparisons due to added complexity and shifted density parameters. The study demonstrates a viable geometric mechanism for acceleration within NC geometry, while highlighting limitations of the Newtonian approach and suggesting future growth-structure analyses and dynamical-systems investigations.

Abstract

We present a novel formulation for the Hubble parameter derived from Newtonian cosmology, incorporating non-commutative fluid dynamics through a deformed Poisson bracket structure. This approach introduces a new cosmological parameter, denoted by $σ$, which emerges naturally from the underlying non-commutative framework. It gives rise to a source term in the background fluid continuity equation, thereby leading to an apparent type of matter creation picture through the resulting non-conservation. Remarkably, the resulting Hubble function accounts for the observed accelerated expansion of the universe without invoking any external dark energy component or cosmological constant. Instead, the parameter $σ$ effectively serves as the driver of acceleration. We further examine the observational constraints on $σ$ using current cosmological data, including the recent Dark Energy Spectroscopic Instrument(DESI) dataset, demonstrating its viability as an alternative explanation for late-time cosmic acceleration within a non-commutative cosmological model.

Figures (8)

• Figure 1: The evolution of deceleration parameter $q(z)$ for different choice of $\sigma$ .
• Figure 2: The evolution of overall equation of state parameter for different choice of $\sigma$
• Figure 3: 2D contour plots with 1D posterior distributions for different combinations of OHD, DESI, and supernova datasets.
• Figure 4: Whisker presentation based on observational constraints on $\sigma$
• Figure 5: The evolution of $q(z)$ on the basis of observational constraints of OHD + SNeIa and OHD + DESI + SNeIa datasets with comparison to $\Lambda$CDM observations