Revisiting Generalized Chaplygin Gas as a Unified Dark Matter and Dark Energy Model

TL;DR

This study re-evaluates the generalized Chaplygin gas model as a unified explanation for dark matter and dark energy, constraining its parameters using multiple cosmological datasets and Markov Chain Monte Carlo analysis.

Contribution

It provides new constraints on the GCG model parameters without separating dark matter and dark energy components, using comprehensive observational data.

Findings

Best-fit parameters: α ≈ 0.00126, Bs ≈ 0.775

Constraints derived from supernova, BAO, and WMAP data

Model remains consistent with observational data

Abstract

In this paper, we revisit generalized Chaplygin gas (GCG) model as a unified dark matter and dark energy model. The energy density of GCG model is given as $\rho_{GCG}/\rho_{GCG0}=[B_{s}+(1-B_{s})a^{-3(1+\alpha)}]^{1/(1+\alpha)}$, where $\alpha$ and $B_s$ are two model parameters which will be constrained by type Ia supernova as standard candles, baryon acoustic oscillation as standard rulers and the seventh year full WMAP data points. In this paper, we will not separate GCG into dark matter and dark energy parts any more as adopted in the literatures. By using Markov Chain Monte Carlo method, we find the result: $\alpha=0.00126_{- 0.00126- 0.00126}^{+ 0.000970+ 0.00268}$ and $B_s= 0.775_{- 0.0161- 0.0338}^{+ 0.0161+ 0.0307}$.