Observational Constraints on Modified Chaplygin Gas from Cosmic Growth

TL;DR

This paper constrains the parameters of the modified Chaplygin gas model as dark energy using observational data on cosmic growth, Hubble parameter, and mass fluctuations, showing it can explain an accelerating universe.

Contribution

It provides the first comprehensive numerical analysis of MCG parameters using multiple observational datasets and growth index models.

Findings

MCG models fit observational data well

MCG predicts an accelerating universe

Best-fit parameters support MCG as viable dark energy

Abstract

We investigate the linear growth function for the large scale structures of the universe considering modified Chaplygin gas as dark energy. Taking into account observational growth data for a given range of redshift from the Wiggle-Z measurements and rms mass fluctuations from Ly-$\alpha$ measurements we numerically analyze cosmological models to constrain the parameters of the MCG. The observational data of Hubble parameter with redshift ($Z$) is also considered. The Wang-Steinhardt ansatz for growth index $\gamma$ and growth function $f$ (defined as $f=\Omega_{m}^{\gamma} (a)$) are considered for the numerical analysis. The best-fit values of the equation of state parameters obtained here is employed to study the growth function $(f)$, growth index ($\gamma$) and state parameter ($\omega$) with redshift $z$. We note that MCG satisfactorily accommodates an accelerating phase followed by a matter dominated universe.