Constraints on the unified dark energy–dark matter model from latest observational data

Abstract

The generalized Chaplygin gas (GCG), is studied in this paper by using the latest observational data including 182 gold sample type Ia supernovae (Sne Ia) data, the ESSENCE Sne Ia data and the distance ratio from z = 0.35 to z = 1089 (the redshift of decoupling). Our results rule out the In addition, we find that the phase transition from deceleration to acceleration occurs at redshift z q=0 ∼ 0.89 − 1.0 at a 1σ confidence level for the GCG model.

Constraints on the generalized Chaplygin gas model including gamma-ray bursts via a Markov Chain Monte Carlo approach

“…1-3 and Table 1, it is shown that the cosmological constant (α = 0) is allowed at the 1-σ confidence level, and the original Chaplygin gas model (α = 1) is ruled out at 95.4% confidence level, which are both consistent with that obtained in Yu (2007c), andLi et al (2009). We can find that GRBs can provide strong constraints when combined with CMB and BAO data without SNe Ia, which has also been noted by Liang, Wu & Zhu (2010), Zhu (2010a), andGao et al (2010).…”

“…In additoin, the constraining results in this work with the joint observational data including GRBs are more stringent than previous results for constraining GCG model parameters with GRBs and/or other combined observations (e.g. Wang et al 2009a,b;Freitasa et al 2010;Davis et al 2007;Wu & Yu 2007c;Li et al 2009;Li et al 2010;Xu & Lu 2010).…”

“…Therefore, the GCG model can be regarded as a derivative of the unified dark matter/energy (UDME) scenario (Bento et al 2004). Until now, the GCG model has been constrained using many different types of observational data, such as Type Ia supernovae (SNe Ia) (Fabris et al 2002;Makler et al 2003a;Colistete et al 2003;Silva & Bertolami 2003;Cunha et al 2004;Bertolami et al 2004;Bento et al 2006;Wu & Yu 2007a), cosmic microwave background (CMB) anisotropy (Bento et al 2003a,b;Bean & Dore 2003;Amendola et al 2003), the angular size of the compact radio sources (Zhu 2004), the X-ray gas mass fraction of clusters (Cunha et al 2004;Makler et al 2003b), the Hubble parameter versus redshift data (Wu & Yu 2007b), largescale structure (Bilić et al 2002;Multamäki et al 2004), gravitational lensing surveys (Dev et al , 2004Chen 2003a,b), age measurements of high-z objects ) and lookback time of galaxy clusters (Li et al 2009); as well as various combinations of data (Wu & Yu 2007c;Davis et al 2007;Li et al 2010;Xu & Lu 2010).…”

On the concordance of cosmological data in the case of the generalized Chaplygin gas

“…This generated again a large interest in the Chaplygin cosmologies and its variants, see e. g. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Most papers assume a flat universe when the allowed parameter space is estimated according to various cosmological data.…”

“…Most papers assume a flat universe when the allowed parameter space is estimated according to various cosmological data. Assuming a flat universe, the 2σ estimation α = −0.14 +0.30 −0.19 is stated in [20] from a joint analysis of supernovae, BAO, and CMB data. A recent analysis, which also assumes a flat universe, finds the 1σ estimation α = −0.03…”