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arXiv 1506.02192astro-ph.CO
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剪切峰统计约束宇宙学:层析分析

Constraining cosmology with shear peak statistics: tomographic analysis

Nicolas Martinet, James G. Bartlett, Alina Kiessling, Barbara Sartoris

摘要:

在弱引力透镜图中丰富的峰值是一个潜在的强大的宇宙学工具,补充剪切功率谱的测量。我们研究直接在剪切图中检测到的峰值,而不是收敛图,这种方法具有直接与可观测量,星系椭圆率目录工作的优势。使用大量的数值模拟来准确预测峰的丰度及其协方差,我们量化了通过类似于欧几里得任务的大面积调查所能达到的宇宙学约束,重点是密度参数Ωm和功率谱归一化σ8。我们提出了一种层析成像峰值计数方法,该方法将条件(边际)约束比来自二维(即,非层析成像)峰计数分析。我们发现,峰值统计提供的约束一个数量级的准确性比那些从集群样本在理想的情况下,一个完美的已知的可观测的质量关系;然而,当缩放关系是不知道的先验,剪切峰约束的两倍强,正交的集群约束,突出使用集群和剪切峰统计的价值。

英文摘要:

The abundance of peaks in weak gravitational lensing maps is a potentially powerful cosmological tool, complementary to measurements of the shear power spectrum. We study peaks detected directly in shear maps, rather than convergence maps, an approach that has the advantage of working directly with the observable quantity, the galaxy ellipticity catalog. Using large numbers of numerical simulations to accurately predict the abundance of peaks and their covariance, we quantify the cosmological constraints attainable by a large-area survey similar to that expected from the Euclid mission, focussing on the density parameter, Ωm, and on the power spectrum normalization, σ8, for illustration. We present a tomographic peak counting method that improves the conditional (marginal) constraints by a factor 1.2 (2) over those from a two-dimensional (i.e., non-tomographic) peak-count analysis. We find that peak statistics provide constraints an order of magnitude less accurate than those from the cluster sample in the ideal situation of a perfectly known observable-mass relation; however, when the scaling relation is not known a priori, the shear-peak constraints are twice as strong and orthogonal to the cluster constraints, highlighting the value of using both clusters and shear-peak statistics.

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