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利用闵可夫斯基泛函和使用代理标度指数来探测CMB中的非Gaussianities指标
Probing non-Gaussianities in the CMB with Minkowski Functionals and Scaling Indices using surrogates |
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| 课程网址: |
http://videolectures.net/nipsworkshops2011_modest_scaling/
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| 主讲教师: |
Heike Modest
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| 开课单位: |
马克斯普朗克研究所
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| 开课时间: |
2012-01-23
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| 课程语种: |
英语
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| 中文简介: |
我们正在分析宇宙微波背景（CMB）与可能的高阶相关（HOC），这将是宇宙原始密度场中非高斯岩石的指标。在这里，对CMB傅立叶相位的分析是一种有前途的宇宙学模型无关的方法。为了生成所谓的替代图，对傅立叶空间中的图应用一种变换格式，可能会破坏原始数据的傅立叶相位的相位相关性（这里是来自WMAP实验的CMB图）。对原始地图和替代地图进行比较之后，可以测试原始地图中是否存在hocs，尤其是在定义良好的比例上。利用Minkowski函数和标度指数作为测试统计，我们发现了在最大尺度上，即在傅里叶模式L从0到20范围内，与高斯CMB假设的偏差，其显著性高达10 Sigma。我们计算了原始数据的测试统计与天空中不同半球的替代数据之间的显著性，发现了半球不对称性以及南北天空中高斯性的偏差。计算天空中较小部分的重要性使我们能够定位南部天空中的某些区域，这些区域显示出与高斯现象的偏差，而在北部发现的信号却消失了。
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| 课程简介: |
We are analysing the cosmic microwave background (CMB) in respect to possible higher order correlations (HOCs) which would be indicators for non-Gaussianities in the primordial density field of the universe. Here, the analysis of the CMB Fourier phases is a promising and cosmological-model independent method. For generating so-called surrogate maps possible phase correlations of the Fourier phases of the original data (here the CMB map from the WMAP experiment) are destroyed applying a shuffling scheme to the maps in Fourier space. A comparison of the original maps and the surrogate maps then allows to test for the presence of HOCs in the original maps, also and especially on well-defined scales. Using Minkowski Functionals and Scaling Indices as test statistics for the HOCs in the maps we find deviations from the hypothesis of a Gaussian CMB with a significance of up to 10 sigma on largest scales, namely within the Fourier modes l from 0 to 20. We calculate the significance between the test statistics of the original data and the surrogates for different hemispheres in the sky and find hemispherical asymmetries as well as deviations from Gaussianity in the northern and southern sky. Calculating the significance for smaller parts of the sky enables us to locate certain regions in the southern sky that show deviations from Gaussianity while the signal found in the north vanishes.
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| 关 键 词: |
宇宙微波背景辐射; 傅里叶相位; 闵可夫斯基函数; 标度指数
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| 课程来源: |
视频讲座网
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| 最后编审: |
2020-07-29：yumf
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| 阅读次数: |
65
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