Constraints on modified Chaplygin gas from large scale structure

Abstract

We study cosmological models with modified Chaplygin gas (MCG) to determine observational constraints on its EoS parameters using the background and the growth tests data. The background test data consists of \(H(z)-z\) data, Baryonic Acoustic Oscillations peak parameter, CMB shift parameter, SN Ia data and the growth test data consists of the linear growth function for the large scale structures of the universe are considered to study MCG in favor of dark energy. For a given range of redshift, the Wiggle-Z measurements and rms mass fluctuations from Ly-\(\alpha \) data, employed for analyzing cosmological models numerically to constrain the MCG parameters. The Wang-Steinhardt ansatz for the growth index (\(\gamma \)) and growth function (\(f\)) are also considered for numerical analysis. The best-fit values of EoS parameters determined here are used to study the variation of \(f\), growth index (\(\gamma \)), EoS parameter, squared sound speed and deceleration parameter with redshift. The constraints on the MCG parameters found here are compared with that of GCG (generalized Chaplygin gas) model for viable cosmology. Cosmologies with MCG satisfactorily describe late acceleration followed by a matter dominated phase. The range of values of EoS parameters, the associated parameters (\(f\), \(\gamma \), \(\omega \), \(\varOmega \), \(c^{2}_{s}\), \(q\)) are also determined from observational data in order to understand the suitability of the MCG model.