The cosmological information of shear peaks: beyond the abundance
The cosmological information of shear peaks: beyond the abundance
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DOI：
10.1093/mnras/stt552
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发表时间：
2013-01
影响因子：
4.8
通讯作者：
L. Marian;Robert E. Smith;Stefan Hilbert;Peter Schneider
中科院分区：
文献类型：
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作者：
L. Marian;Robert E. Smith;Stefan Hilbert;Peter Schneider
我们研究了弱透镜峰的宇宙学信息，除了它们的丰度外，还关注了另外两个统计量：堆叠的切向剪切轮廓和峰-峰相关函数。我们使用一个大的合奏模拟WL地图与调查规格相关的未来的任务，如欧几里得和lsst，测量和检查的三个峰值探头。我们发现，从大小为144 deg 2的场测量的具有高信噪比（S（N））的峰的自相关函数在角标度#n 10 arcmin处具有最大值n 0.3。对于具有较小S{N}的峰，相关函数的幅度减小，并且其最大值出现在较小的角度尺度上。峰的堆叠切向剪切轮廓也随着它们的S{N}而增加。我们比较了在具有和不具有形状噪声的情况下测量的峰值可观测量，并且发现对于S{Nn 3}，只有5%的峰值是由于大尺度结构，其余的由形状噪声产生。因此，与从无噪声图测量的小峰相比，这些小峰的相关函数非常弱，并且它们的平均切向剪切轮廓比无噪声的小几倍。探针的协方差矩阵进行了检查：相关函数仅在尺度#30 arcmin上弱协变，并且在较大尺度上略多;剪切剖面对于#2 arcmin非常相关，相关系数高达0.7。三种探针的交叉协方差相对较弱：峰丰度和谱图具有最大的相关系数n 0.3。使用费舍尔矩阵形式主义，我们计算宇宙学约束的tm，β 8，w，nsu考虑每个探针单独，以及组合。我们发现，峰-峰相关和剪切剖面产生的边缘化误差比单独由峰丰度产生的误差大2 '4倍，而tw，nsu的误差是相似的。通过组合三个探针，与单独的峰丰度相比，边缘化的约束被收紧因子n2，对误差减少的贡献最小的是相关函数。因此，这项工作建议未来的WL调查使用剪切峰超出其丰度，以限制宇宙学模型。
We study the cosmological information of weak lensing (WL) peaks, focusing on two other statistics besides their abundance: the stacked tangential-shear profiles and the peak-peak correlation function. We use a large ensemble of simulated WL maps with survey specifications relevant to future missions like Euclid and lsst, to measure and examine the three peak probes. We find that the auto-correlation function of peaks with high signal-to-noise (S{N) ratio measured from fields of size 144 deg 2 has a maximum of „ 0.3 at an angular scale # „ 10 arcmin. For peaks with smaller S{N, the amplitude of the correlation function decreases, and its maximum occurs on smaller angular scales. The stacked tangential-shear profiles of the peaks also increase with their S{N. We compare the peak observables measured with and without shape noise and find that for S{N „ 3 only „ 5% of the peaks are due to large-scale structures, the rest being generated by shape noise. The correlation function of these small peaks is therefore very weak compared to that of small peaks measured from noise-free maps, and also their mean tangential-shear profile is a factor of a few smaller than the noise-free one. The covariance matrix of the probes is examined: the correlation function is only weakly covariant on scales # ă 30 arcmin, and slightly more on larger scales; the shear profiles are very correlated for # ą 2 arcmin, with a correlation coefficient as high as 0.7. The cross-covarianceof the three probes is relatively weak: the peak abundance and profiles have the largest correlation coefficient „ 0.3. Using the Fisher-matrix formalism, we compute the cosmological constraints for tm, �8, w, nsu considering each probe separately, as well as in combination. We find that the peakpeak correlation and shear profiles yield marginalized errors which are larger by a factor of 2´4 for tm, �8u than the errors yielded by the peak abundance alone, while the errors for tw, nsu are similar. By combining the three probes, the marginalized constraints are tightened by a factor of „ 2 compared to the peak abundance alone, the least contributor to the error reduction being the correlation function. This work therefore recommends that future WL surveys use shear peaks beyond their abundance in order to constrain the cosmological model.