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Observational Constraints on the Structure-Induced Dark Energy Model

A. Kazım Çamlıbel

Abstract

A new phenomenological dark energy model, originally associated to the large-scale structure formation and considered as a solution to the fine-tuning and coincidence problems related to the cosmological constant, was analyzed within the framework of General Relativity in a Friedman-Robertson-Walker spacetime and its model parameters were estimated using cosmic chronometers and recent DESI data. It turns out that the proposed model can serve as an alternative evolving dark energy model with a novel equation of state function, apart from other popular propositions in the literature. Due to the form of this phenomenological energy density ansatz, which starts to rise with the nonlinear structure growth in the universe and falls with the domination of cosmic voids, we prefer to call it structure-induced dark energy. Observational constraints show that it is not only a suitable solution for the fundamental problems such as coincidence or fine-tuning problems, it gives flexibility, when considering the cosmic tensions and presents a new perspective on the evolving dark energy models.

Observational Constraints on the Structure-Induced Dark Energy Model

Abstract

A new phenomenological dark energy model, originally associated to the large-scale structure formation and considered as a solution to the fine-tuning and coincidence problems related to the cosmological constant, was analyzed within the framework of General Relativity in a Friedman-Robertson-Walker spacetime and its model parameters were estimated using cosmic chronometers and recent DESI data. It turns out that the proposed model can serve as an alternative evolving dark energy model with a novel equation of state function, apart from other popular propositions in the literature. Due to the form of this phenomenological energy density ansatz, which starts to rise with the nonlinear structure growth in the universe and falls with the domination of cosmic voids, we prefer to call it structure-induced dark energy. Observational constraints show that it is not only a suitable solution for the fundamental problems such as coincidence or fine-tuning problems, it gives flexibility, when considering the cosmic tensions and presents a new perspective on the evolving dark energy models.
Paper Structure (4 sections, 6 equations, 6 figures, 1 table)

This paper contains 4 sections, 6 equations, 6 figures, 1 table.

Table of Contents

  1. Introduction
  2. Characteristics of the SIDE Model
  3. Data and Analysis
  4. Conclusion

Figures (6)

  • Figure 1: Plots showing the evolution of the SIDE density, $\rho$, for varying each three model parameters, consecutively, where the other two were kept constant, such that, (a) $z_* =$ 5 (blue), 10 (black), 20 (red) (b) $\alpha =$ 1.5 (red), 1 (black), 0.5 (blue) (c) $\beta =$ 1.5 (red), 1 (black), 0.5 (blue).
  • Figure 2: Evolution of the equation of state parameter, $w$, for (a) $\alpha =$ 1.5 (red), 1 (black), 0.5 (blue) (b) $\beta =$ 1.5 (red), 1 (black), 0.5 (blue), together with $w=-1$ line (dashed). For each panel, the other parameter and $z_*$ were kept constant
  • Figure 3: $H(z)$ data derived from cosmic chronometers (blue) moresco2022unveiling and from DESI DR1 distance data (gold) adame2025desi.
  • Figure 4: Best fits for $\Lambda$CDM (blue) and SIDE$_{10}$ (red), with 1-$\sigma$ confidence intervals (dashed), together with DESI DR1 $H(z)$ datapoints.
  • Figure 5: Evolution of the energy density, $\rho$, for the best fitting SIDE$_{10}$, when the cosmic chronometers and DESI DR1 considered together.
  • ...and 1 more figures