A Modified Generalized Chaplygin Gas as the Unified Dark Matter-Dark Energy Revisited

作者：Deng, Xue-Mei^*

来源：Brazilian Journal of Physics, 2011, 41(4-6): 333-348.

DOI：10.1007/s13538-011-0044-z

• Dark energy
• Dark matter

A modified generalized Chaplygin gas (MGCG) is considered as the unified dark matter-dark energy revisited. The character of MGCG is endued with the dual role, which behaves as matter at early times and as a quiessence dark energy at late times. The equation of state for MGCG is p = -alpha rho/(1 + alpha) - nu(z)rho(-alpha)/(1 + alpha), where nu(z) = -[rho(0c)(1 + z)(3)]((1 + alpha))(1 - Omega(0B))(alpha) {alpha Omega(0DM) + Omega(0DE)[omega(DE) + alpha(1 + omega(DE))](1 + z)3(omega DE(1+alpha))}. Some cosmological quantities, such as the densities of different components of the universe Omega(i) (i, respectively, denotes baryons, dark matter, and dark energy) and the deceleration parameter q, are obtained. The present deceleration parameter q(0), the transition redshift z(T), and the redshift z(eq), which describes the epoch when the densities in dark matter and dark energy are equal, are also calculated. To distinguish MGCG from others, we then apply the Statefinder diagnostic. Later on, the parameters (alpha and omega(DE)) of MGCG are constrained by combination of the sound speed c(s)(2), the age of the universe t(0), the growth factor m, and the bias parameter b. It yields alpha = -3.07(-4.98)(+5.66) x 10(-2) and omega(DE) = -1.05(-0.11)(+0.06). Through the analysis of the growth of density perturbations for MGCG, it is found that the energy will transfer from dark matter to dark energy which reach equal at z(eq) similar to 0.48 and the density fluctuations start deviating from the linear behavior at z similar to 0.25 caused by the dominance of dark energy.

• 出版日期2011-12
• 单位中国科学院紫金山天文台