Bulk flow and shear in the local Universe: 2MTF and cosmicflows-3
Bulk flow and shear in the local Universe: 2MTF and cosmicflows-3
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DOI：
10.1093/mnras/sty2826
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发表时间：
2018-10
影响因子：
4.8
通讯作者：
F. Qin;C. Howlett;L. Staveley-Smith;T. Hong
中科院分区：
文献类型：
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作者：
F. Qin;C. Howlett;L. Staveley-Smith;T. Hong
星系的低阶运动学矩，即体流和剪切，使我们能够测试理论模型是否能够准确地描述附近宇宙中质量密度场的演化。我们使用所谓的eta MLE最大似然估计在对数距离空间来衡量themoments从2 MASS塔利-费舍尔（2 MTF）调查和COSMICFLOWS-3（CF 3）汇编的组合样本。2 MTF和CF 3之间的Galerkin共同证明了-0.016 +/- 0.002 dex的小零点差。我们测试的eta MLE 16模拟2 MTF调查目录，以探讨如何以及eta MLE恢复的真实时刻，和样品各向异性的影响。在37 h（-1）Mpc的尺度下，我们发现局域宇宙的整体流为259 +/-15 km s（-1），方向为（l，B）=（300 +/-4度，23 +/-3.）（银河系坐标）。平均剪切振幅为1.7 +/- 0.4 h km s（-1）Mpc（-1）。我们使用一个可变的窗口函数来探索体积和剪切力矩作为深度的函数。在所有情况下，测量结果都与Lambda冷暗物质（Lambda CDM）模型的预测一致。
The low-order kinematic moments of galaxies, namely bulk flow and shear, enables us to test whether theoretical models can accurately describe the evolution of the mass density field in the nearby Universe. We use the so-called eta MLE maximum likelihood estimator in log-distance space to measure thesemoments from a combined sample of the 2MASS Tully-Fisher (2MTF) survey and the COSMICFLOWS-3 (CF3) compilation. Galaxies common between 2MTF and CF3 demonstrate a small zero-point difference of -0.016 +/- 0.002 dex. We test the eta MLE on 16 mock 2MTF survey catalogues in order to explore how well the eta MLE recovers the true moments, and the effect of sample anisotropy. On the scale size of 37 h(-1) Mpc, we find that the bulk flow of the local Universe is 259 +/- 15 km s(-1) in the direction is (l, b) = (300 +/- 4 degrees, 23 +/- 3.) (Galactic coordinates). The average shear amplitude is 1.7 +/- 0.4 h km s(-1) Mpc(-1). We use a variable window function to explore the bulk and shear moments as a function of depth. In all cases, the measurements are consistent with the predictions of the Lambda cold dark matter (Lambda CDM) model.