DYNAMICAL CENTERS AND NONCIRCULAR MOTIONS IN THINGS GALAXIES: IMPLICATIONS FOR DARK MATTER HALOS
DYNAMICAL CENTERS AND NONCIRCULAR MOTIONS IN THINGS GALAXIES: IMPLICATIONS FOR DARK MATTER HALOS
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DOI：
10.1088/0004-6256/136/6/2720
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发表时间：
2008-10
期刊：
影响因子：
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通讯作者：
C. Trachternach;W. D. Blok;F. Walter;E. Brinks;R. Kennicutt
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作者：
C. Trachternach;W. D. Blok;F. Walter;E. Brinks;R. Kennicutt
我们提出了谐波分解的速度场的19个星系的H i附近星系巡天（THINGS），量化的幅度在这些星系的非圆运动，并产生观测估计的暗物质晕电位的伸长率。此外，我们提出了准确的动力学中心的位置，这些星系。我们表明，在我们的样本中的绝大多数星系的运动学和光度中心的位置是在很好的协议。在我们的样本中，非圆运动的平均绝对振幅为6.7 km s-1，其中90%的星系的非圆运动的平均振幅小于9.9 km s-1。作为总旋转速度的一部分，这平均转化为4.5%。在对未知视角进行统计校正后，引力势的平均伸长为0.017 ± 0.020，这与圆势一致。我们推导出的非圆运动和伸长小于使冷暗物质（CDM）模拟与观测一致所需的。特别是，振幅的非圆运动是不够高，以隐藏陡峭的中心质量密度分布预测CDM模拟。我们发现，非圆运动的振幅减少朝向较低的光度和以后的哈勃类型。
We present harmonic decompositions of the velocity fields of 19 galaxies from The H i Nearby Galaxy Survey (THINGS) which quantify the magnitude of the noncircular motions in these galaxies and yield observational estimates of the elongations of the dark matter halo potentials. Additionally, we present accurate dynamical center positions for these galaxies. We show that the positions of the kinematic and photometric centers of the large majority of the galaxies in our sample are in good agreement. The median absolute amplitude of the noncircular motions, averaged over our sample, is 6.7 km s−1, with ∼90% of the galaxies having median noncircular motions of less than ∼9 km s−1. As a fraction of the total rotation velocity, this translates into 4.5% on average. The mean elongation of the gravitational potential, after a statistical correction for an unknown viewing angle, is 0.017 ± 0.020, which is consistent with a round potential. Our derived noncircular motions and elongations are smaller than what is needed to bring cold dark matter (CDM) simulations in agreement with the observations. In particular, the amplitudes of the noncircular motions are not high enough to hide the steep central mass–density profiles predicted by CDM simulations. We show that the amplitudes of the noncircular motions decrease toward lower luminosities and later Hubble types.