Cosmological constraints on alternative model to Chaplygin fluid revisited

TL;DR

This paper revisits an alternative to Chaplygin gas as a unified dark matter and dark energy model, constraining it with recent cosmological data and finding it consistent with observations, thus supporting its viability.

Contribution

It introduces and constrains a modified perfect fluid model with a single parameter, demonstrating its consistency with current cosmological observations as an alternative to Chaplygin gas.

Findings

Estimated model parameter μ around 0.84 for flat universe

Derived current deceleration parameter q₀ ≈ -0.67

Estimated universe age approximately 13.1 Gyr

Abstract

In this work we explore an alternative phenomenological model to Chaplygin gas proposed by H. Hova et. al., consisting on a modification of a perfect fluid, to explain the dynamics of dark matter and dark energy at cosmological scales immerse in a flat or curved universe. Adopting properties similar to a Chaplygin gas, the proposed model is a mixture of dark matter and dark energy components parameterized by only one free parameter denoted as $\mu$. We focus on contrasting this model with the most recent cosmological observations of Type Ia Supernovae and Hubble parameter measurements. Our joint analysis yields a value $\mu = 0.843^{+0.014}_{-0.015}\,$ ($0.822^{+0.022}_{-0.024}$) for a flat (curved) universe. Furthermore, with these constraints we also estimate the deceleration parameter today $q_0=-0.67 \pm 0.02\,(-0.51\pm 0.07)$, the acceleration-deceleration transition redshift $z_t=0.57\pm 0.04\, (0.50 \pm 0.06)$, and the universe age $t_A = 13.108^{+0.270}_{-0.260}\,\times (12.314^{+0.590}_{-0.430})\,$Gyrs. We also report a best value of $\Omega_k = 0.183^{+0.073}_{-0.079}$ consistent at $3\sigma$ with the one reported by Planck Collaboration. Our analysis confirm the results by Hova et al, this Chaplygin gas-like is a plausible alternative to explain the nature of the dark sector of the universe.