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arXiv 1104.1635astro-ph.CO
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星系成团的宇宙学约束和星系团的质数比

Cosmological Constraints from Galaxy Clustering and the Mass-to-Number Ratio of Galaxy Clusters

Jeremy L. Tinker, Erin S. Sheldon, Risa H. Wechsler, Matthew R. Becker, Eduardo Rozo, Ying Zu, David H. Weinberg, Idit Zehavi, Michael Blanton, Michael Busha, Benjamin P. Koester

摘要:

我们把约束的平均密度(Ω_m)和集群的振幅(sigma_8)的物质使用的组合的两个测量从斯隆数字巡天:星系两点关联函数,w_p,和质量星系团内的数量比星系团,M/N,类似于集群M/L比。我们的w_p测量是从DR 7得到的,而星系团的样本是maxBCG样本,星系团的质量来自弱引力透镜。我们利用Halo Occupation Distribution(HOD)构造了非线性的星系偏置模型,以拟合不同宇宙学参数下的w_p和M/N。当Omega_m或sigma_8变化时,匹配相同两点聚类的HOD模型预测了不同数量的星系在大质量晕中,从而打破了宇宙学和偏差之间的简并性。我们证明,这种技术产生的限制,是一致的和竞争力的集群丰度研究的当前结果,即使这种技术不使用丰度信息。单独使用w_p和M/N,我们发现Omega_m^0.5*sigma_8=0.465+/-0.026,其中单个约束条件为Omega_m=0.29+/-0.03和sigma_8=0.85+/-0.06。结合当前CMB数据,这些约束条件为Omega_m=0.290+/-0.016和sigma_8=0.826+/-0.020。所有误差均为1-sigma。系统的不确定性,M/N技术是最敏感的暗物质晕的偏置函数的振幅和红移之间的SDSS主样本和maxBCG样本的演化的可能性。我们推导出的约束是不敏感的晕质量函数和质量丰富的关系集群和其分散的不确定性,使M/N技术的补充集群丰度作为一种方法,用于约束宇宙学与未来的星系调查。

英文摘要:

We place constraints on the average density (Omega_m) and clustering amplitude (sigma_8) of matter using a combination of two measurements from the Sloan Digital Sky Survey: the galaxy two-point correlation function, w_p, and the mass-to-galaxy-number ratio within galaxy clusters, M/N, analogous to cluster M/L ratios. Our w_p measurements are obtained from DR7 while the sample of clusters is the maxBCG sample, with cluster masses derived from weak gravitational lensing. We construct non-linear galaxy bias models using the Halo Occupation Distribution (HOD) to fit both w_p and M/N for different cosmological parameters. HOD models that match the same two-point clustering predict different numbers of galaxies in massive halos when Omega_m or sigma_8 is varied, thereby breaking the degeneracy between cosmology and bias. We demonstrate that this technique yields constraints that are consistent and competitive with current results from cluster abundance studies, even though this technique does not use abundance information. Using w_p and M/N alone, we find Omega_m^0.5*sigma_8=0.465+/-0.026, with individual constraints of Omega_m=0.29+/-0.03 and sigma_8=0.85+/-0.06. Combined with current CMB data, these constraints are Omega_m=0.290+/-0.016 and sigma_8=0.826+/-0.020. All errors are 1-sigma. The systematic uncertainties that the M/N technique are most sensitive to are the amplitude of the bias function of dark matter halos and the possibility of redshift evolution between the SDSS Main sample and the maxBCG sample. Our derived constraints are insensitive to the current level of uncertainties in the halo mass function and in the mass-richness relation of clusters and its scatter, making the M/N technique complementary to cluster abundances as a method for constraining cosmology with future galaxy surveys.

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