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arXiv 0911.4973astro-ph.CO
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从弱透镜和星系团直接重建暗物质关联函数的算法

An algorithm for the direct reconstruction of the dark matter correlation function from weak lensing and galaxy clustering

Tobias Baldauf, Robert E. Smith, Uros Seljak, Rachel Mandelbaum

摘要:

在宇宙学尺度上的物质成团是研究宇宙的物理起源和组成的一个必要的探针。迄今为止,大多数的直接研究集中在剪切弱透镜相关,但也有可能提取的暗物质集群相结合的星系集群和星系-星系-透镜测量。在这项研究中,我们开发了一种方法,可以限制暗物质的关联函数从星系集群和星系-星系-透镜测量,通过专注于星系和物质的密度场之间的相关系数。为了生成用于测试目的的模拟星系目录,我们使用Halo Occupation Distribution方法应用于N体模拟的大型集合,以模拟预先存在的SDSS亮红星系样本观测。使用这个模拟目录,我们表明,直接比较透镜测量的多余表面质量密度和其相应的星系集群数量是不理想的。我们开发了一个新的统计,抑制小规模的贡献,这些观察,并表明,这个新的统计导致的互相关系数,是在百分之几的团结下降到5兆秒差距/小时。此外,星系和物质场之间的残余不相干性可以使用尺度依赖偏差的理论模型来解释,给我们一个最终的估计值,它的无偏性在1%以内。我们还对其他可能影响分析的物理效应进行了全面的研究,例如红移空间扭曲和星系聚类和弱透镜观测之间的径向窗口差异。我们将该方法应用于一系列宇宙学模型,并展示了我们的新统计量的可行性,以区分宇宙学模型。

英文摘要:

The clustering of matter on cosmological scales is an essential probe for studying the physical origin and composition of our Universe. To date, most of the direct studies have focused on shear-shear weak lensing correlations, but it is also possible to extract the dark matter clustering by combining galaxy-clustering and galaxy-galaxy-lensing measurements. In this study we develop a method that can constrain the dark matter correlation function from galaxy clustering and galaxy-galaxy-lensing measurements, by focusing on the correlation coefficient between the galaxy and matter overdensity fields. To generate a mock galaxy catalogue for testing purposes, we use the Halo Occupation Distribution approach applied to a large ensemble of N-body simulations to model pre-existing SDSS Luminous Red Galaxy sample observations. Using this mock catalogue, we show that a direct comparison between the excess surface mass density measured by lensing and its corresponding galaxy clustering quantity is not optimal. We develop a new statistic that suppresses the small-scale contributions to these observations and show that this new statistic leads to a cross-correlation coefficient that is within a few percent of unity down to 5 Mpc/h. Furthermore, the residual incoherence between the galaxy and matter fields can be explained using a theoretical model for scale-dependent bias, giving us a final estimator that is unbiased to within 1%. We also perform a comprehensive study of other physical effects that can affect the analysis, such as redshift space distortions and differences in radial windows between galaxy clustering and weak lensing observations. We apply the method to a range of cosmological models and show the viability of our new statistic to distinguish between cosmological models.

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