Testing the (generalized) Chaplygin gas model with the Lookback time-Redshift data

TL;DR

This study tests the generalized Chaplygin gas model using look-back time and baryonic acoustic oscillation data, finding it viable as a dark matter-energy candidate but ruling out the original Chaplygin gas at high confidence.

Contribution

It provides observational constraints on the generalized Chaplygin gas model using combined look-back time and BAO data, refining its viability as a dark energy candidate.

Findings

Both CG and GCG models are consistent with data as dark matter-energy unification candidates.

The original Chaplygin gas model ($=1$) is ruled out at 99.7% confidence level.

Combined data constrains model parameters within specific confidence intervals.

Abstract

The Chaplygin gas (CG) and the generalized Chaplygin gas (GCG) models, proposed as candidates of the unified dark matter-dark energy (UDME), are tested with the look-back time (LT) redshift data. We find that the LT data only give a very weak constraint on the model parameter. However, by combing the LT with the baryonic acoustic oscillation peak, we obtain, at the 95.4% confidence level, $0.68\leq A_c\leq0.82$ and $0.59\leq h\leq0.65$ for the CG model, and $0.67\leq A_s\leq0.89$ and $-0.29\leq \alpha\leq0.61$ for the GCG model. This shows that both the CG and the GCG are viable as a candidate of UDME. Within the GCG model, we also find that the Chaplygin gas model ($\alpha=1$) is ruled out by these data at the 99.7% confidence level.