首页>
外文期刊>The Astrophysical journal
>COSMIC FLOW FROM TWO MICRON ALL-SKY REDSHIFT SURVEY: THE ORIGIN OF COSMIC MICROWAVE BACKGROUND DIPOLE AND IMPLICATIONS FOR ΛCDM COSMOLOGY
【24h】
COSMIC FLOW FROM TWO MICRON ALL-SKY REDSHIFT SURVEY: THE ORIGIN OF COSMIC MICROWAVE BACKGROUND DIPOLE AND IMPLICATIONS FOR ΛCDM COSMOLOGY
We generate the peculiar velocity field for the Two Micron All-Sky 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 3000?km?s–1. We estimate the mean matter density to be Ωm = 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 3000?km?s–1 agrees with the observed motion and is generated by fluctuations within this volume, in agreement with observations. Having tested our method against observed distances, we reconstruct the velocity field of 2MRS in successively larger radii, to study the problem of convergence toward the cosmic microwave background (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 h –1 Mpc. Although most of the amplitude of the CMB dipole seems to be recovered by 120 h –1 Mpc, the direction does not agree and hence we observe no convergence up to this scale. Due to dominant superclusters such as Shapley or Horologium-Reticulum in the southern hemisphere at scales above 120 h –1 Mpc, one might need to go well beyond 200 h –1 Mpc to fully recover the dipole vector. We develop a statistical model which allows us to estimate cosmological parameters from the reconstructed growth of convergence of the velocity of the Local Group toward the CMB dipole motion. For scales up to 60 h –1 Mpc, assuming a Local Group velocity of 627 km s–1, we estimate Ωm h 2 = 0.11 ± 0.06 and σ8 = 0.9 ± 0.4, in agreement with WMAP5 measurements at the 1σ level. However, for scales up to 100 h –1?Mpc, we obtain Ωm h 2 = 0.08 ± 0.03 and σ8 = 1.0 ± 0.4, which agrees at the 1σ to 2σ level with WMAP5 results.
展开▼
机译：我们使用轨道重建算法为“两微米全天红移测量”（2MRS）目录生成了特殊的速度场。 2MRS中单个物体的重建速度与从3000？km？s–1内的高精度观测距离获得的特殊速度密切相关。通过比较观察到的体积中的重建速度，我们估计平均物质密度为Ωm= 0.31±0.05。通过在3000？km？s–1之内的距离建立的静止帧中的本地组的重构运动与观察到的运动一致，并由该体积内的波动生成，与观察一致。在针对观测距离测试了我们的方法之后，我们在连续更大的半径中重建了2MRS的速度场，以研究向宇宙微波背景（CMB）偶极子收敛的问题。我们发现，在大约40 h –1 Mpc的封闭Hydra-Centaurus-Norma超团簇的体积内，只有不到CMB偶极子振幅的一半。尽管CMB偶极子的大部分振幅似乎可以在120 h –1 Mpc的范围内恢复，但方向却不一致，因此我们观察到在此范围内都没有收敛。由于南半球的Shapley或Horologium-Reticulum等主要的超级团簇的规模超过120 h –1 Mpc，人们可能需要远远超过200 h –1 Mpc才能完全恢复偶极子矢量。我们开发了一个统计模型，该模型使我们能够从本地组向CMB偶极子运动速度收敛的重构增长量估计宇宙学参数。对于高达60 h – 1 Mpc的尺度，假设局部群速度为627 km s–1，我们估计Ωmh 2 = 0.11±0.06和σ8= 0.9±0.4，与WMAP5在1σ水平的测量结果一致。但是，对于不超过100 h –1？Mpc的标度，我们获得Ωmh 2 = 0.08±0.03和σ8= 1.0±0.4，这与WMAP5结果在1σ至2σ水平上一致。
展开▼
