星系中的重子振荡与物质功率谱协方差矩阵
Baryon oscillations in galaxy and matter power-spectrum covariance matrices
摘要：
本文研究了宇宙学功率谱协方差矩阵非对角项中的大振幅重子声学振荡（BAO）。这些协方差矩阵BAO的描述的功率谱BAO的大规模功率的向上波动所造成的衰减增加。我们推导出一个解析近似的协方差矩阵条目在BAO制度，并检查使用N体模拟的分析预测。这些BAO在功率谱上看起来比BAO强得多，但在千兆秒差距尺度的星系巡天中，似乎只能在大约一西格玛的水平上探测到。在利用物质或星系功率谱估计宇宙学参数时，包括协方差矩阵BAO对一些与BAO直接相关的参数（如重子分数）的误差条宽度有百分之几的影响。此外，我们发现，在调查中，包括在小晕的众多星系可以减少这些宇宙学参数的误差条比简单的减少散粒噪声可能会建议。
英文摘要：
We investigate large-amplitude baryon acoustic oscillations (BAO's) in off-diagonal entries of cosmological power-spectrum covariance matrices. These covariance-matrix BAO's describe the increased attenuation of power-spectrum BAO's caused by upward fluctuations in large-scale power. We derive an analytic approximation to covariance-matrix entries in the BAO regime, and check the analytical predictions using N-body simulations. These BAO's look much stronger than the BAO's in the power spectrum, but seem detectable only at about a one-sigma level in gigaparsec-scale galaxy surveys. In estimating cosmological parameters using matter or galaxy power spectra, including the covariance-matrix BAO's can have a several-percent effect on error-bar widths for some parameters directly related to the BAO's, such as the baryon fraction. Also, we find that including the numerous galaxies in small haloes in a survey can reduce error bars in these cosmological parameters more than the simple reduction in shot noise might suggest.
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