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arXiv 0810.3658astro-ph
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2 MASS红移观测的宇宙流:CMB偶极的起源及其对LCDM宇宙学的影响

Cosmic flow from 2MASS redshift survey: The origin of CMB dipole and implications for LCDM cosmology

G. Lavaux, R. Brent Tully, R. Mohayaee, S. Colombi

摘要:

我们使用轨道重建算法生成2 MASS红移巡天(2 MRS)星表的特殊速度场。在2 MRS中重建的单个物体的速度与从3,000 km/s以内的高精度观测距离获得的特殊速度具有良好的相关性。我们估计平均物质密度为0.31 +/- 0.05,通过比较观察到的重建速度在这个体积。本星系群在静止坐标系中的重建运动与观测到的运动一致,由3,000 km/s以内的距离建立,并且是由该体积内的波动产生的,与观测一致。然后,我们重建的速度场的2 MRS在连续更大的半径,研究的问题,收敛到CMB偶极子。我们发现,不到一半的振幅的CMB偶极子内的体积包围的Hydra-Centaurus-Norma超星系团在40 Mpc/h左右产生。虽然大部分的振幅的CMB偶极子似乎是由120兆秒差距/小时恢复,方向不同意,因此我们没有观察到收敛到这个规模。我们开发了一个统计模型,使我们能够估计宇宙学参数的重建增长的收敛速度的本地集团对CMB偶极运动。对于高达60 Mpc/h的尺度,假设局域群速度为627 km/s,我们估计Omega_m h^2 = 0.11 +/- 0.06和sigma_8=0.9 +/- 0.4,与WMAP 5在1-sigma水平上的测量结果一致。然而,对于高达100 Mpc/h的尺度,我们得到Omega_m h^2 = 0.08 +/- 0.03和sigma_8=1.0 +/- 0.4,这与WMAP 5结果在1到2-sigma水平上一致。(节略)

英文摘要:

We generate the peculiar velocity field for the 2MASS Redshift Survey (2MRS) catalog using an orbit-reconstruction algorithm. The reconstructed velocities of individual objects in 2MRS are well-correlated with the peculiar velocities obtained from high-precision observed distances within 3,000 km/s. We estimate the mean matter density to be 0.31 +/- 0.05 by comparing observed to reconstructed velocities in this volume. The reconstructed motion of the Local Group in the rest frame established by distances within 3,000 km/s agrees with the observed motion and is generated by fluctuations within this volume, in agreement with observations. Then, we reconstruct the velocity field of 2MRS in successively larger radii, to study the problem of convergence towards the CMB dipole. We find that less than half of the amplitude of the CMB dipole is generated within a volume enclosing the Hydra-Centaurus-Norma supercluster at around 40 Mpc/h. Although most of the amplitude of the CMB dipole seems to be recovered by 120 Mpc/h, the direction does not agree and hence we observe no convergence up to this scale. We develop a statistical model which allows us to estimate cosmological para meters from the reconstructed growth of convergence of the velocity of the Local Group towards the CMB dipole motion. For scales up to 60 Mpc/h, assuming a Local Group velocity of 627 km/s, we estimate Omega_m h^2 = 0.11 +/- 0.06 and sigma_8=0.9 +/- 0.4, in agreement with WMAP5 measurements at the 1-sigma level. However, for scales up to 100 Mpc/h, we obtain Omega_m h^2 = 0.08 +/- 0.03 and sigma_8=1.0 +/- 0.4, which agrees at the 1 to 2-sigma level with WMAP5 results. (abridged)

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