A mathematical analysis of the evolution of perturbations in a modified Chaplygin gas model

Abstract

One approach in modern cosmology consists in supposing that dark matter and dark energy are different manifestations of a single "quartessential" fluid. Following such idea, this work presents a study of the evolution of perturbations of density in a flat cosmological model with a modified Chaplygin gas acting as a single component. Our goal is to obtain properties of the model which can be used to distinguish it from another cosmological models which have the same solutions for the general evolution of the scale factor of the universe, without the construction of the power spectrum. Our analytical results, which alone can be used to uniquely characterize the specific model studied in our work, show that the evolution of the density contrast can be seen, at least in one particular case, as composed by a spheroidal wave function. We also present a numerical analysis which clearly indicates as one interesting feature of the model the appearance of peaks in the evolution of the density contrast.

A study of Universal thermodynamics in Lanczos–Lovelock gravity

“…The dynamics of the MCG model was studied by Wu et al [60] whereas Bedran et al [61] studied the evolution of the temperature function in the presence of a MCG. It is also consistent with perturbative studies [62] and the spherical collapse problem [63]. The equation of state for MCG is given by [40,64] p = γρ − B ρ n1 (38) where γ (≤ 1) , B, n 1 are positive constant.…”

Warm modified Chaplygin gas shaft inflation

“…where ω is a constant parameter, with 0 ≤ σ ≤ 1, is suitable to describe the evolution of the universe [71,72] which is also consistent with perturbative study [73]. The energy conservation equation for the MCG model turns out to be…”

Combined constraints on modified Chaplygin gas model from cosmological observed data: Markov Chain Monte Carlo approach

“…The correspondences between the MCG and the ordinary scalar field [25,26], the tachyon theory [25][26][27][28][29], and the holographic dark energy density [30,31] of the universe have been studied. In principle, MCG represents the evolution of the universe starting from the radiation era to the era dominated by the cosmological constant [32][33][34][35]. In addition, MCG is also applied to inflation theory [36][37][38][39].…”