Title: Reionization and CMB non-Gaussianity Show Chinese title

Title: 再电离和CMB非高斯性

Abstract: We show how cross-correlating a high redshift external tracer field, such as the 21cm neutral hydrogen distribution and product maps involving Cosmic Microwave Background (CMB) temperature and polarisation fields, that probe mixed bispectrum involving these fields, can help to determine the reionization history of the Universe, beyond what can be achieved from cross-spectrum analysis. Taking clues from recent studies for the detection of primordial non-Gaussianity (Munshi & Heavens 2010), we develop a set of estimators that can study reionization using a power spectrum associated with the bispectrum (or skew-spectrum). We use the matched filtering inherent in this method to investigate different reionization histories. We check to what extent they can be used to rule out various models of reionization and study cross contamination from different sources such as the lensing of the CMB. The estimators can be fine-tuned to optimize study of a specific reionization history. We consider three different types of tracers in our study, namely: proto-galaxies; 21cm maps of neutral hydrogen; quasars. We also consider four alternative models of reionization. We find that the cumulative signal-to-noise (S/N) for detection at $\ell_{max}=2000$ can reach $\mathcal{O}(70)$ for cosmic variance limited all-sky experiments. Combining 100GHz, 143GHz and 217GHz channels of the Planck experiment, we find that the (S/N) lies in the range $\mathcal{O}(5)-\mathcal{O}(35)$. The (S/N) depends on the specific choice of a tracer field, and multiple tracers can be effectively used to map out the entire reionization history with reasonable S/N. Contamination from weak lensing is investigated and found to be negligible, and the effects of Thomson scattering from patchy reionizationare also considered. Show Chinese abstract

Abstract: 我们展示如何通过交叉相关高红移外部示踪场，如21cm中性氢分布和涉及宇宙微波背景(CMB)温度和极化场的产品图，来探测这些场的混合双谱，从而确定宇宙再电离历史，这超越了从交叉谱分析中可以实现的范围。 借鉴最近关于原初非高斯性的检测研究（Munshi & Heavens 2010），我们开发了一组估计量，可以利用与双谱（或偏度谱）相关的功率谱来研究再电离过程。 我们使用该方法中的匹配滤波来研究不同的再电离历史。 我们检查它们在多大程度上可用于排除各种再电离模型，并研究来自不同源的交叉污染，例如CMB的弱透镜效应。 这些估计量可以微调以优化对特定再电离历史的研究。 在我们的研究中，我们考虑了三种不同类型的示踪场，即：原星系；中性氢的21cm图；类星体。 我们还考虑了四种替代的再电离模型。 我们发现，在$\ell_{max}=2000$处的累积信噪比(S/N)对于宇宙方差受限的全天空实验可以达到$\mathcal{O}(70)$。 结合普朗克实验的100GHz、143GHz和217GHz通道，我们发现(S/N)位于$\mathcal{O}(5)-\mathcal{O}(35)$范围内。 (S/N)取决于示踪场的具体选择，多个示踪场可以有效地用于以合理的S/N绘制整个再电离历史。 研究了弱透镜的污染，发现其可以忽略不计，并且也考虑了不均匀再电离的汤姆孙散射的影响。