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arXiv 0705.0063astro-ph
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银河系热介质与宇宙微波背景

The Hot Inter-Galactic Medium and the Cosmic Microwave Background

Michael Fisher

摘要:

的莱曼α森林云系统的物理特性相结合的观测宇宙的重子质量密度和约束从原始核合成设置边界条件的星系际介质(IGM)在时代的z=2.5。宇宙被认为是一个封闭的系统,并允许从类星体第一次电离IGM(5 <= z_on <= 20)的时代开始膨胀。气体的平均动能是在气体从相对论行为转变为非相对论行为的区域中计算的。所有的测量结果被用来确定IGM在红移范围2.5 <= z <= z_on的热历史。热IGM被假定为逆康普顿散射光子从宇宙微波背景(CMBR),从而扭曲的CMBR在目前的时间看到的。在上面定义的约束内,调整z=2.5处的IGM的温度和时期z_on,以给出与关于IGM的温度的公开数据的最佳总体一致性。我们发现,这里提出的IGM模型并没有严重扭曲的CMBR,事实上同意相当接近的初步结果从宇宙背景探测器(COBE)卫星。然而,我们的IGM模型不能解释观测到的宇宙X射线背景。这篇论文最初写于1990年。它从未提交出版。

英文摘要:

The physical characteristics of the Lyman-alpha forest cloud systems are combined with observations on the baryonic mass density of the Universe and constraints from primordial nucleosynthesis to set boundary conditions on the Intergalactic Medium (IGM) at the epoch of z=2.5. The Universe is considered a closed system and allowed to expand adiabatically from the epoch when QSOs first ionized the IGM (5 <= z_on <= 20). The average kinetic energy of a gas is calculated in the region where the gas transitions from relativistic to non-relativistic behavior. All of the above measurements are then used to determine the thermal history of the IGM in the redshift range 2.5 <= z <= z_on. The hot IGM is assumed to inverse Compton scatter photons from the Cosmic Microwave Background (CMBR) and consequently distort the CMBR as seen at the present epoch. The temperature of the IGM at z=2.5 and the epoch z_on are adjusted, within the constraints defined above, to give the best overall agreement with published data on the temperature of the IGM. We find that the model of the IGM proposed here does not grossly distort the CMBR, and in fact agrees quite closely with the preliminary results from the Cosmic Background Explorer (COBE) satellite. However, our model of the IGM cannot explain the observed cosmic x ray background. This paper was originally written in 1990. It was never submitted for publication.

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