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arXiv 1203.1002astro-ph.CO
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具有成团各向异性的宇宙学:星系红移巡天中动力学和几何扭曲的解开

Cosmology with clustering anisotropies: disentangling dynamic and geometric distortions in galaxy redshift surveys

Federico Marulli, Davide Bianchi, Enzo Branchini, Luigi Guzzo, Lauro Moscardini, Raul E. Angulo

摘要:

我们调查的影响,不同的观测效果影响的波动的增长率的精确和准确的测量星系红移调查的各向异性集群的影响。我们专注于红移测量误差,重建的基础上的实空间集群和存在的明显的简并与宇宙学相关的红移转换成距离引起的几何失真。我们使用一套模拟目录提取的大型N体模拟,侧重于分析中间,轻度非线性尺度和应用标准的线性色散模型,以适应所观察到的关联函数的各向异性。我们验证了高达~0.2%的红移误差对可以测量特定生长率β的精度的影响可以忽略不计。较大的红移误差引入正的系统误差,这可以通过采用成对速度的高斯分布函数来减轻。这是,在任何情况下,小于系统误差高达10%,由于线性色散模型的限制,这是在一个单独的文件中研究。然后,我们表明,50%的统计误差预算β依赖于解投影程序,通过该程序获得的实空间关联函数。最后,我们证明了与几何失真的退化,其实可以规避。这是通过在红移空间中的Alcock-Paczynski检验的修改版本获得的,它通过搜索优化动力学红移失真描述的解决方案成功地恢复了正确的宇宙学。对于一个平坦的宇宙学,我们得到了很大程度上独立的,强大的约束β和欧米茄。在体积为2.4(Gpc/h)^[3]的情况下,只要正确地重建实空间关联函数,就可以得到正确的Ω M,误差约为12%,偏差可以忽略不计。

英文摘要:

We investigate the impact of different observational effects affecting a precise and accurate measurement of the growth rate of fluctuations from the anisotropy of clustering in galaxy redshift surveys. We focus on redshift measurement errors, on the reconstruction of the underlying real-space clustering and on the apparent degeneracy existing with the geometrical distortions induced by the cosmology-dependent conversion of redshifts into distances. We use a suite of mock catalogues extracted from large N-body simulations, focusing on the analysis of intermediate, mildly non-linear scales and apply the standard linear dispersion model to fit the anisotropy of the observed correlation function. We verify that redshift errors up to ~0.2% have a negligible impact on the precision with which the specific growth rate beta can be measured. Larger redshift errors introduce a positive systematic error, which can be alleviated by adopting a Gaussian distribution function of pairwise velocities. This is, in any case, smaller than the systematic error of up to 10% due to the limitations of the linear dispersion model, which is studied in a separate paper. We then show that 50% of the statistical error budget on beta depends on the deprojection procedure through which the real-space correlation function is obtained. Finally, we demonstrate that the degeneracy with geometric distortions can in fact be circumvented. This is obtained through a modified version of the Alcock-Paczynski test in redshift-space, which successfully recovers the correct cosmology by searching for the solution that optimizes the description of dynamical redshift distortions. For a flat cosmology, we obtain largely independent, robust constraints on beta and OmegaM. In a volume of 2.4(Gpc/h)^3, the correct OmegaM is obtained with ~12% error and negligible bias, once the real-space correlation function is properly reconstructed.

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