Joint analysis of cluster number counts and weak lensing power spectrum to correct for the super-sample covariance
Joint analysis of cluster number counts and weak lensing power spectrum to correct for the super-sample covariance
复制标题
DOI：
10.1093/mnras/stu759
复制
发表时间：
2013-07
影响因子：
4.8
通讯作者：
M. Takada;D. Spergel;D. Spergel
中科院分区：
文献类型：
--
作者：
M. Takada;D. Spergel;D. Spergel
在有限的测量体积上，一个相干的过密度或欠密度对比会导致观测到的晕数向上或向下波动。晕圈数的这种波动在非线性、小尺度上的弱透镜功率谱的观测振幅中增加了一个显着的协变散射，即所谓的超样本方差或晕圈样本方差。在本文中，我们表明，通过测量集群的数量计数和功率谱在同一个调查区域，我们可以减轻这种信息的损失，并显着提高科学回报，从即将到来的调查。首先，使用晕模型的方法，我们推导出晕数计数和弱透镜功率谱之间的互相关，考虑到超样本协方差效应，这很好地匹配从1000个实现的Lambda主导的冷暗物质模型测量的分布。然后，我们表明，增加观测到的M> 10^14 Ms/h的质量晕的计数可以显着提高弱透镜功率谱的信息含量，几乎恢复高斯信息高达lmax~1000，如果已知的质量晕的平均质量分布，这可以从堆叠透镜估计。当与M > 3或1 x 10^14 Ms/h的晕圈数计数相结合时，在lmax~1000 - 2000范围内，改进可达1.4或2倍，与单独的功率谱测量相比，相当于大2或4倍的调查体积。
A coherent over- or under-density contrast across a finite survey volume causes an upward- or downward-fluctuation in the observed number of halos. This fluctuation in halo number adds a significant co-variant scatter in the observed amplitudes of weak lensing power spectrum at nonlinear, small scales -- the so-called super-sample variance or the halo sample variance. In this paper, we show that by measuring both the number counts of clusters and the power spectrum in the same survey region, we can mitigate this loss of information and significantly enhance the scientific return from the upcoming surveys. First, using the halo model approach, we derive the cross-correlation between the halo number counts and the weak lensing power spectrum, taking into account the super-sample covariance effect, which well matches the distributions measured from 1000 realizations for a Lambda-dominated cold dark matter model. Then we show that adding the observed number counts of massive halos with M> 10^14 Ms/h can significantly improve the information content of weak lensing power spectrum, almost recovering the Gaussian information up to lmax~1000, if the average mass profiles of the massive halos are known, which can be estimated from stacked lensing. When combined with the halo number counts for M > 3 or 1 x 10^14 Ms/h, the improvement is up to a factor of 1.4 or 2 at lmax~1000 --2000, equivalent to a factor 2 or 4 times larger survey volume, compared to the power spectrum measurement alone.