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arXiv 1202.0090astro-ph.CO
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通过重建重子声学振荡获得z=0.35的2%距离-- I:方法及其在Sloan数字巡天中的应用

A 2% Distance to z=0.35 by Reconstructing Baryon Acoustic Oscillations - I : Methods and Application to the Sloan Digital Sky Survey

Nikhil Padmanabhan, Xiaoying Xu, Daniel J. Eisenstein, Richard Scalzo, Antonio J. Cuesta, Kushal T. Mehta, Eyal Kazin

摘要:

我们将重建技术应用于SDSS DR 7 LRG样本的星系聚类,锐化了重子声学振荡(BAO)特征,并实现了1.9%的距离测量z=0.35。这是第一次应用重建的BAO功能的星系红移调查。我们更新了Eisenstein等人,2007年的重建算法,占调查的几何形状以及红移空间失真的影响,并验证了160 LasDamas模拟。我们证明,重建锐化角平均星系关联函数中的BAO特征,将非线性平滑尺度从8.1 Mpc/h减小到4.4 Mpc/h。重建也显着减少了红移空间失真的影响,在BAO尺度,各向同性的关联函数。这种锐化的BAO特征产生无偏距离估计(< 0.2%),并将分散度从3.3%降低到2.1%。我们证明了这些结果的鲁棒性的各种重建参数,包括平滑尺度,星系的偏见和线性增长率。将该重建算法应用于SDSS LRG DR 7样本,将这些数据中的BAO特征的显著性从未重建的关联函数的3.3 σ提高到重建后的4.2 σ。我们估计相对距离尺度D_V/r_s到z=0.35为8.88+/-0.17,其中r_s是声音地平线,D_V =(D_A^2/H)^{1/3}是角直径距离D_A和哈勃参数H的组合。假设声音水平线为154.25 Mpc,这转化为距离测量D_V(z=0.35)= 1.356+/-0.025 Gpc。我们发现,重建减少了DR 7样本的距离误差从3.5%到1.9%,相当于三倍的SDSS体积的调查。

英文摘要:

We apply the reconstruction technique to the clustering of galaxies from the SDSS DR7 LRG sample, sharpening the baryon acoustic oscillation (BAO) feature and achieving a 1.9% measurement of the distance to z=0.35. This is the first application of reconstruction of the BAO feature in a galaxy redshift survey. We update the reconstruction algorithm of Eisenstein et al, 2007 to account for the effects of survey geometry as well as redshift-space distortions and validate it on 160 LasDamas simulations. We demonstrate that reconstruction sharpens the BAO feature in the angle averaged galaxy correlation function, reducing the nonlinear smoothing scale Σ_nl from 8.1 Mpc/h to 4.4 Mpc/h. Reconstruction also significantly reduces the effects of redshift-space distortions at the BAO scale, isotropizing the correlation function. This sharpened BAO feature yields an unbiased distance estimate (< 0.2%) and reduces the scatter from 3.3% to 2.1%. We demonstrate the robustness of these results to the various reconstruction parameters, including the smoothing scale, the galaxy bias and the linear growth rate. Applying this reconstruction algorithm to the SDSS LRG DR7 sample improves the significance of the BAO feature in these data from 3.3 sigma for the unreconstructed correlation function, to 4.2 sigma after reconstruction. We estimate a relative distance scale D_V/r_s to z=0.35 of 8.88+/-0.17, where r_s is the sound horizon and D_V = (D_A^2/H)^{1/3} is a combination of the angular diameter distance D_A and Hubble parameter H. Assuming a sound horizon of 154.25 Mpc, this translates into a distance measurement D_V (z=0.35) = 1.356+/-0.025 Gpc. We find that reconstruction reduces the distance error in the DR7 sample from 3.5% to 1.9%, equivalent to a survey with three times the volume of SDSS.

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