Generalized Chaplygin gas model: Cosmological consequences and statefinder diagnosis

TL;DR

This paper investigates the generalized Chaplygin gas (GCG) model's cosmological implications, including its evolution, statefinder diagnostics, and comparison with observational data, showing it behaves as a unified dark energy and dark matter model.

Contribution

The paper provides a detailed analysis of the GCG model's cosmological behavior, deriving statefinder parameters and comparing its evolution with observational data, highlighting its similarities and differences with other models.

Findings

GCG behaves as quintessence, pressureless matter, and cosmological constant at different epochs.

The transition from deceleration to acceleration depends on GCG parameters.

GCG's statefinder trajectory is closer to $\\Lambda$CDM than standard Chaplygin gas.

Abstract

The generalized Chaplygin gas (GCG) model in spatially flat universe is investigated. The cosmological consequences led by GCG model including the evolution of EoS parameter, deceleration parameter and dimensionless Hubble parameter are calculated. We show that the GCG model behaves as a general quintessence model. The GCG model can also represent the pressureless CDM model at the early time and cosmological constant model at the late time. The dependency of transition from decelerated expansion to accelerated expansion on the parameters of model is investigated. The statefinder parameters $r$ and $s$ in this model are derived and the evolutionary trajectories in $s-r$ plane are plotted. Finally, based on current observational data, we plot the evolutionary trajectories in $s-r$ and $q-r$ planes for best fit values of the parameters of GCG model. It has been shown that although, there are similarities between GCG model and other forms of chaplygin gas in statefinder plane, but the distance of this model from the $\Lambda$CDM fixed point in $s-r$ diagram is shorter compare with standard chaplygin gas model.