Large‐scale non‐Gaussianities in the 21‐cm background anisotropies from the era of reionization
Large‐scale non‐Gaussianities in the 21‐cm background anisotropies from the era of reionization
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再电离时代的 21 厘米背景各向异性中的大尺度非高斯性
DOI：
10.1111/j.1365-2966.2005.09506.x
复制
发表时间：
2004
影响因子：
4.8
通讯作者：
A. Cooray
中科院分区：
文献类型：
--
作者：
A. Cooray
在21厘米背景的亮度温度波动有关的中性氢分布提供了一个探针的物理再电离的时代，当星系际介质从完全中性的部分电离的变化。我们制定的统计21厘米的亮度温度各向异性的角功率谱，双谱，和三谱。使用三谱，我们估计的协方差相关的功率谱测量和显示，非高斯性导致的相关性低于百分之一，最多。虽然可以用角分尺度分辨率的21厘米背景的全天观测来测量累积信噪比为几十的双谱，但在存在前景和与第一代干涉仪有关的仪器噪声的情况下，这种测量不太可能可行。在大多数情况下，21厘米波动的非高斯性可以忽略，分布可以用高斯统计来描述。由于21厘米的波动受到前景的严重污染，如银河同步加速器或低频无线电点源，信号中缺乏显著的非高斯性表明任何显著的非高斯性检测都可能是前景的结果。类似地，除了现在提出的用于将21厘米波动与前景分开的频率信息之外，如果先验已知前景的非高斯结构，则这些附加信息可能会用于进一步减少混乱。
The brightness temperature fluctuations in the 21-cm background related to the neutral hydrogen distribution provide a probe of the physics related to the era of reionization, when the intergalactic medium changed from being completely neutral to partially ionized. We formulate statistics of 21-cm brightness temperature anisotropies in terms of the angular power spectrum, the bispectrum, and the trispectrum. Using the trispectrum, we estimate the covariance related to the power spectrum measurements and show that correlations resulting from non-Gaussianities are below a per cent, at most. While all-sky observations of the 21-cm background at arcminute-scale resolution can be used to measure the bispectrum with a cumulative signal-to-noise ratio of the order of a few tens, in the presence of foregrounds and instrumental noise related to first-generation interferometers, the measurement is unlikely to be feasible. For most purposes, non-Gaussianities in 21-cm fluctuations can be ignored and the distribution can be described with Gaussian statistics. Because 21-cm fluctuations are significantly contaminated by foregrounds, such as galactic synchrotron or low-frequency radio point sources, the lack of significant non-Gaussianity in the signal suggests that any significant detection of non-Gaussianity could be the result of foregrounds. Similarly, in addition to the frequency information that is now proposed to separate 21-cm fluctuations from foregrounds, if the non-Gaussian structure of foregrounds is known a priori, this additional information could potentially be used to reduce the confusion further.
DOI：
10.1111/j.1365-2966.2003.07316.x
发表时间：
2003-09
影响因子：
4.8
作者：
Xuelei Chen;A. Cooray;N. Yoshida;N. Sugiyama
通讯作者：
Xuelei Chen;A. Cooray;N. Yoshida;N. Sugiyama
影响因子：
8.7
作者：
Bennett, CL;Halpern, M;Weiland, JL
通讯作者：
Weiland, JL