Observational constraints on a unified dark matter and dark energy model based on generalized Chaplygin gas

TL;DR

This paper tests a generalized Chaplygin gas model as a unified dark matter and dark energy candidate against various cosmological observations, finding it closely resembles the standard Lambda-CDM model within current constraints.

Contribution

It provides observational constraints on a two-parameter generalized Chaplygin gas model, evaluating its viability as a unified dark matter and dark energy framework.

Findings

Model is tightly constrained by current data.

Allowed parameter space is very close to Lambda-CDM.

The model can mimic standard cosmology within observational limits.

Abstract

We study a generalized version of Chaplygin gas as unified model of dark matter and dark energy. Using realistic theoretical models and the currently available observational data from the age of the universe, the expansion history based on the type Ia supernovae, the matter power spectrum, the cosmic microwave background radiation anisotropy power spectra, and the perturbation growth factor we put the unified model under observational test. As the model has only two free parameters in the flat Friedmann background [$\Lambda$CDM (cold dark matter) model has only one free parameter] we show that the model is already tightly constrained by currently available observations. The only parameter space extremely close to the $\Lambda$CDM model is allowed in this unified model.