WMAP five-year data constraints on the unified model of dark energy and dark matter

We investigate observational constraints on the generalized Chaplygin gas (GCG) model as the unification of dark matter and dark energy from the latest observational data: the Union SNe Ia data, the observational Hubble data, the SDSS baryon acoustic peak and the fiveyear WMAP shift parameter. The result is obtained that the best-fit values of the GCG model parameters with their confidence level are A s = 0.73 (2σ ). Furthermore, in this model, we can see that the evolution of equation of state (EOS) for dark energy is similar to quiessence, and its current best-fit value is w 0de = −0.96 with the 1σ confidence level −0.91 ≥ w 0de ≥ −1.00.

Section: Introductionmentioning

confidence: 99%

Observational constraint on generalized Chaplygin gas model

Gui

2009

“…In these unified dark fluid models, the Chaplygin gas (CG) and its generalized model have been widely studied for interpreting the accelerating universe [13,14,15,16]. The most interesting property for this scenario is that, two unknown dark sections in universe-dark energy and dark matter can be unified by using an exotic equation of state.…”

Section: Introductionmentioning

confidence: 99%

Revisiting generalized Chaplygin gas as a unified dark matter and dark energy model

Wang

2012

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 ρGCG/ρGCG0, where α and Bs 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: α = 0.00126 +0.000970+0.00268 −0.00126−0.00126 and Bs = 0.775

“…As a competitive model to explain the lately accelerated expansion of universe, a unified dark fluid (UDF) model [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] was investigated extensively in the recent years. The striking features of the UDF model are that it combines cold dark matter and dark energy and that it behaves like the cold dark matter and the dark energy at an early epoch and a late time, respectively.…”

Section: Introductionmentioning

confidence: 99%

Spherical top-hat collapse of a viscous unified dark fluid

Wei

2014

In this paper, we test the spherical collapse of a viscous unified dark fluid (VUDF) which has constant adiabatic sound speed and show the nonlinear collapse for VUDF, baryons, and dark matter, which are important in forming the large-scale structure of our Universe. By varying the values of the model parameters α and ζ 0 , we discuss their effects on the nonlinear collapse of the VUDF model, and we compare its result to the CDM model. The results of the analysis show that, within the spherical top-hat collapse framework, larger values of α and smaller values of ζ 0 make the structure formation earlier and faster, and the other collapse curves are almost distinguished with the curve of CDM model if the bulk viscosity coefficient ζ 0 is less than 10 −3 .