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具有非高斯初始条件的宇宙学中的宇宙剪切统计

Cosmic shear statistics in cosmologies with non-Gaussian initial conditions

C. Fedeli, L. Moscardini

备注：
15 pages, 10 figures. Accepted by MNRAS
发表信息：
Mon.Not.Roy.Astron.Soc.405:681-694,2010
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摘要：

我们计算了具有非高斯原始密度涨落的模型中弱宇宙剪切的功率谱。偏离高斯性的宇宙学初始条件最近在文献中引起了很大的关注，特别是关于它们对非线性结构形成的影响，以及它们可以对暴胀时代施加的限制。完全非线性的物质功率谱进行了评估与使用的物理动机，半解析晕模型，其中的质量函数和线性晕偏差进行了适当的校正，为非高斯宇宙学。与以前的工作一致，我们发现，与CMB界限兼容的非高斯性水平和正偏度在中间尺度上产生几个百分点的功率增加。然后，我们使用的物质功率谱，连同观测动机的背景源红移分布，以计算宇宙学弱透镜功率谱。我们发现，从参考高斯模型的功率谱的偏差程度是小的统计误差相比，甚至从未来的弱透镜调查。然而，在一个大范围的多极子上对信号求和可以降低噪声，当所有其他宇宙学参数保持固定时，在$|f_\mathrm{NL}| \simeq $几十的水平上显著检测到非高斯性。最后，我们已经表明，非高斯水平上的约束可以改善$\sim 20%$与使用弱透镜层析成像。

英文摘要：

We computed the power spectrum of weak cosmic shear in models with non-Gaussian primordial density fluctuations. Cosmological initial conditions deviating from Gaussianity have recently attracted much attention in the literature, especially with respect to their effect on the formation of non-linear structures and because of the bounds that they can put on the inflationary epoch. The fully non-linear matter power spectrum was evaluated with the use of the physically motivated, semi-analytic halo model, where the mass function and linear halo bias were suitably corrected for non-Gaussian cosmologies. In agreement with previous work, we found that a level of non-Gaussianity compatible with CMB bounds and with positive skewness produces an increase in power of the order of a few percent at intermediate scales. We then used the matter power spectrum, together with observationally motivated background source redshift distributions in order to compute the cosmological weak lensing power spectrum. We found that the degree of deviation from the power spectrum of the reference Gaussian model is small compared to the statistical error expected from even future weak lensing surveys. However, summing the signal over a large range of multipoles can beat down the noise, bringing to a significant detection of non-Gaussianity at the level of $|f_\mathrm{NL}| \simeq $ few tens, when all other cosmological parameters are held fixed. Finally, we have shown that the constraints on the level of non-Gaussianity can be improved by $\sim 20%$ with the use of weak lensing tomography.

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