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arXiv 1105.4099astro-ph.CO
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利用高红移大质量星系团作为宇宙学探针的新方法

On a novel approach using massive clusters at high redshifts as cosmological probe

J. -C. Waizmann, S. Ettori, L. Moscardini

摘要:

在这项工作中,我们提出了一种新的方法来测试的有效性的基准LCDM宇宙学的测量最大质量的晕在一个样本中的子体积相同的大小平铺在天空中的一个固定的红移的累积分布函数。事实上,最大质量的集群探测的质量函数,LCDM和替代宇宙学模型之间的差异是最强的高质量的尾巴,使我们的方法特别有趣的宇宙学探测。我们利用一般极值统计(GEV),以获得在给定的体积中最大质量的对象的累积分布函数。我们抽样这个分布函数,根据所覆盖的调查区域的一系列不同的“测试宇宙学”和不同的准确质量估计的晕补丁的数量。通过用GEV分布函数拟合这个样本,我们可以研究哪些参数对测试宇宙学最敏感。我们发现,一旦我们能够在红移大于z=1(z=1.5)时建立一个足够完整的大面积观测,M_lim=10^14.5 M_sun/h(M_lim=10^14 M_sun/h),最大质量晕的概率分布函数的峰值非常适合检验基准LCDM模型的有效性。作为累积性的,所提出的措施是强大的,在集群质量的20-30%的准确度将足以测试替代模型。由于只需要在每个角补丁中最大的系统,这种方法将非常适合作为第一个快速一致性检查,然后再进入一个更复杂的统计分析观察到的晕样本。

英文摘要:

In this work we propose a novel method for testing the validity of the fiducial LCDM cosmology by measuring the cumulative distribution function of the most massive haloes in a sample of subvolumes of identical size tiled on the sky at a fixed redshift. The fact that the most massive clusters probe the high-mass tail of the mass function, where the difference between LCDM and alternative cosmological models is strongest, makes our method particularly interesting as a cosmological probe. We utilise general extreme value statistics (GEV) to obtain a cumulative distribution function of the most massive objects in a given volume. We sample this distribution function according to the number of patches covered by the survey area for a range of different "test cosmologies" and for differently accurate mass estimations of the haloes. By fitting this sample with the GEV distribution function, we can study which parameters are the most sensitive with respect to the test cosmologies. We find that the peak of the probability distribution function of the most massive halo is well suited to test the validity of the fiducial LCDM model, once we are able to establish a sufficiently complete large-area survey with M_lim=10^14.5 M_sun/h (M_lim=10^14 M_sun/h) at redshifts above z=1 (z=1.5). Being of cumulative nature the proposed measure is robust and an accuracy of 20-30% in the cluster masses would be sufficient to test for alternative models. Since one only needs the most massive system in each angular patch, this method would be ideally suited as a first fast consistency check before going into a more complex statistical analysis of the observed halo sample.

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