偏离$Λ$ CDM：压力参数化
Deviation from $Λ$CDM: Pressure Parametrization
摘要：
大多数暗能量的参数化都涉及到暗能量的状态方程$w$。在这项工作中，我们选择的暗能量的压力参数化。由于$p = constant$本质上给出了一个宇宙学常数，我们使用围绕这个行为的泰勒展开$p = -p_{0} + (1-a)p_{1} + ....$来研究与宇宙学常数的微小偏差。在我们的模型中，偏离宇宙学常数的行为已经被建模的额外的K-本质领域的存在，而保持宇宙学常数项不变。该模型类似于辅助暴胀场景，在某种意义上，对于泰勒级数展开的任何高阶偏差，都需要多个K本质场。我们还测试了我们的模型与最近的观测数据来自Ia型超新星的测量，重子振荡峰（BAO）和气体的质量分数的星系团从X射线观测推断，并获得我们的模型参数的约束。
英文摘要：
Most parametrizations for dark energy involve the equation of state $w$ of the dark energy. In this work, we choose the pressure of the dark energy to parametrize. As $p = constant$ essentially gives a cosmological constant, we use the Taylor expansion around this behavior $p = -p_{0} + (1-a)p_{1} + ....$ to study the small deviations from the cosmological constant. In our model, the departure from the cosmological constant behavior has been modeled by the presence of extra K-essence fields while keeping the cosmological constant term untouched. The model is similar to assisted inflation scenario in a sense that for any higher order deviation in terms of Taylor series expansion, one needs multiple K-essence fields. We have also tested our model with the recent observational data coming from Supernova type Ia measurements, the baryon oscillations peak (BAO) and the gas mass fraction of the galaxy clusters inferred from X-ray observations and obtain constraints for our model parameters.
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