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Probing the Deep Universe by Cosmic Microwave Background Temperature Anisotropies

利用宇宙微波背景温度各向异性探测宇宙深处

基本信息

批准号：
14540290
负责人：
SUGIYAMA Naoshi
金额：
$ 1.98万
依托单位：
National A.stronomical Observatory
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540290/
关键词：
Cosmology Cosmic Microwave Background Radiation Structure Formation Early Stellar Formation

项目摘要

We utilize temperature anisotropies of cosmic microwave background (CMB) to probe the early universe.(1) We investigate the accuracy of the numerical calculations for time evolution of temperature anisotropies. Making a comparison with three independent codes, we achieve the level of less than 0.2% numerical errors. With the use of this newly build code, we can make a precise determination of various cosmological parameters.(2) We set a tight constraint on the gravitational constant from the latest WMAP observations since the physical size of the universe at 400,000 years old, which relates to the observed size of temperature patters, is a function of the gravitational constant. We found that the difference of the gravitational constant at 400,000 years and the present epoch has to be less than 5%.(3) We propose three models for early reionization of the universe which is suggested by WMAP observations. It is known that the standard cold dark matter model can hardly have such early reionization. First one is to introduce a non-Gaussian statistical feature in density fluctuations. The non-Gaussian tail of high density fluctuations can induce early enough structure formation. Secondly, we consider unknown massive particles which emit UV lights during the decay process. This UV lights ionized the intergalactic medium. Finally, we introduce the isocurvature mode in density fluctuations together with the ordinary adiabatic mode. This isocurvature mode solely induces early structure formation.(4) We expect to have a polarization component in CMB, which is produced by the scattering off photons by electrons. If we look at the direction of a cluster of galaxies, we always can detect CMB through this cluster. However, the polarization changes its direction due to Fraday rotation. From the precise measurements of CMB polarization toward the cluster direction, we found that we can reconstruct cluster magnetic fields.

我们利用宇宙微波背景辐射的温度各向异性来探测早期宇宙。(1)我们调查的准确性的数值计算的时间演变的温度各向异性。与三个独立的代码进行比较，我们实现了小于0.2%的数值误差的水平。使用这个新构建的代码，我们可以精确地确定各种宇宙学参数。(2)我们从最新的WMAP观测中对引力常数设置了严格的约束，因为宇宙在40万年前的物理大小与观测到的温度模式大小有关，是引力常数的函数。我们发现，40万年前的引力常数与现在的引力常数之差必须小于5%。(3)我们提出了WMAP观测所建议的宇宙早期再电离的三种模型。据了解，标准的冷暗物质模型几乎不可能有这样的早期再电离。第一个是在密度涨落中引入非高斯统计特征。高密度涨落的非高斯尾可以诱导足够早的结构形成。其次，我们考虑在衰变过程中发射紫外光的未知大质量粒子。这种紫外线使星系际介质电离。最后，我们介绍了密度涨落中的等曲率模和普通绝热模。这种等曲率模式仅诱导早期结构形成。(4)我们希望在CMB中有一个极化分量，它是由电子散射光子产生的。如果我们看一个星系团的方向，我们总是可以通过这个星系团探测到CMB。然而，偏振由于Fraday旋转而改变其方向。通过对团簇方向CMB极化的精确测量，我们发现可以重建团簇磁场。

项目成果

期刊论文数量（31）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Probing Intracluster Magnetic Fields with Cosmic Microwave Background Polarization

用宇宙微波背景偏振探测簇内磁场

DOI：
发表时间：
2003
期刊：
Astrophysical Journal 584
影响因子：
0
作者：
Hiroshi Ohno;Masahiro Takada;Klaus Dolag;Matthias Bartelmann;Naoshi Sugiyama
通讯作者：
Naoshi Sugiyama

S.Kasuya, M.Kawasaki, Naoshi Sugiyama: "Partially ionizing the universe by decaying particles"Physical Review. D69. 023512 (2004)

S.Kasuya、M.Kawasaki、Naoshi Sugiyama：“通过衰变粒子部分电离宇宙”物理评论。