Can a large‐scale structure probe cosmic microwave background‐constrained non‐Gaussianity?
Can a large‐scale structure probe cosmic microwave background‐constrained non‐Gaussianity?
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大型结构能否探测宇宙微波背景约束的非高斯性？
DOI：
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发表时间：
2007
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影响因子：
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通讯作者：
J. Silk
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作者：
X. Kang;P. Norberg;J. Silk
第一年的威尔金森微波各向异性探测器（WMAP）对任何原始非高斯性的振幅设置了定量约束。我们在WMAP约束下运行了一系列纯暗物质（DM-only） n体模拟，以研究原始非高斯性对大尺度结构的影响。假设星系速度偏差可以正确建模，模型参数可以通过高红移（2≤z≤4）与Lyα发射体相关的原星系团的观测来约束。与宇宙微波背景相比，高红移结构的形成可能提供了一个更有力的原始非高斯性测试，尽管是在更小的尺度上。另一个约束是由2dF星系红移巡天（2dFGRS）绘制的局部星系密度概率分布函数（PDF）给出的。2dFGRS星系的PDF大大高于标准模型预测，并且需要星系和DM之间在~ 12 h−1 Mpc尺度上的不可忽略的偏差，以及比WMAP第一年数据所允许的更强的非高斯性。后一种解释是首选的，因为二阶偏差修正是负的。由于功率谱波动归一化程度较低，σ8= 0.74，与WMAP三年数据一致，高斯模型与数据的差异更大。
The first-year Wilkinson Microwave Anisotropy Probe (WMAP) set quantitative constraints on the amplitude of any primordial non-Gaussianity. We run a series of dark matter-only (DM-only) N-body simulations with the WMAP constraints to investigate the effect of the presence of primordial non-Gaussianity on large-scale structures. The model parameters can be constrained using the observations of protoclusters associated with Lyα emitters at high redshift (2 ≤z≤ 4), assuming that the galaxy velocity bias can be modelled properly. High-redshift structure formation potentially provides a more powerful test of possible primordial non-Gaussianity than does the cosmic microwave background, albeit on smaller scales. Another constraint is given by the local galaxy density probability distribution function (PDF), as mapped by the 2dF Galaxy Redshift Survey (2dFGRS). The PDF of 2dFGRS galaxies is substantially higher than the standard model predictions and requires either a non-negligible bias between galaxy and DM on ∼12 h−1 Mpc scales and a stronger non-Gaussianity than that allowed by the WMAP first-year data. The latter interpretation is preferred since second-order bias corrections are negative. With a lower normalization of the power spectrum fluctuations, σ8= 0.74, as favoured by the WMAP three-year data, the discrepancy between the Gaussian model and the data is even larger.