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arXiv 0801.0290astro-ph
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宇宙微波背景对与热演化有关的衰减宇宙学项的约束

Cosmic microwave background constraints on a decaying cosmological term related to the thermal evolution

Riou Nakamura, Masa-aki Hashimoto, Kiyotomo Ichiki

摘要:

利用Wilkinson微波各向异性探测器(WMAP)观测数据的分析方法,用衰减的宇宙学项来约束宇宙的热演化。宇宙学项被假定为一个向早期宇宙方向增加的比例因子的函数,辐射能量密度比标准宇宙学“常数”(LCDM)模型中的低。辐射密度的降低会影响宇宙的热历史;例如,与标准LCDM模型的情况相比,光子去耦发生在更高的z处。因此,衰减的宇宙学项影响宇宙微波背景的各向异性。利用马尔可夫链蒙特卡罗方法,我们比较了衰减LCDM模型的角功率谱和CMB数据,得到了对模型参数的严格约束。

英文摘要:

We constrain the thermal evolution of the universe with a decaying cosmological term by using the method of the analysis for the Wilkinson Microwave Anisotropy Probe (WMAP) observation data. The cosmological term is assumed to be a function of the scale factor that increases toward the early universe, and the radiation energy density is lower compared to that in the model with the standard cosmological "constant" (LCDM). The decrease in the radiation density affects the thermal history of the universe; e.g. the photon decoupling occurs at higher-z compared to the case of the standard LCDM model. As a consequence, a decaying cosmological term affects the cosmic microwave background anisotropy. Thanks to the Markov-chain Monte Carlo method, we compare the angular power spectrum in the decaying LCDM model with the CMB data, and we get severe constraints on parameters of the model.

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