双指数势Cardassian宇宙模型

对存在通常物质与双指数势标量场的Cardassian宇宙模型进行了研究，并分析了它的动力学性质．Cardassian模型对Friedmann方程引入修正项以符合目前观测的宇宙加速膨胀现象．对修正后的Friedmann方程选取适当的无量纲化，使得两项不同性质的能量密度在不同能量标度的极限下，分别现显出前者主要影响支配宇宙的高能时期，而后者影响支配宇宙的低能时期．计算结果表明，双指数势将影响宇宙演化，最终由其中一个优势项决定演化方式．

Cardassian cosmological models with double exponential

In this paper, we study the Cardassian cosmological models filled with a barotropic fluid and a scalar field with double exponential potentials and analyze their dynamical characters. Cardassian models require the Friedmann equation modified with a term to correspond to the cosmological accelerated expansion. We choose appropriately normalized variables for modified Friedmann equation to adapte the different energy density in respective energy limits. The former is best adapted for high energy period and the latter is well for low energy period. The results of our calculation show that the double exponential potentials affect the final evolution of universe which will tend to one of them.