Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS3D and SINS/zC-SINF
Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS3D and SINS/zC-SINF
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DOI：
10.3847/1538-4357/aa6d82
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
P. Lang;N. F. Schreiber;R. Genzel;R. Genzel;S. Wuyts;E. Wisnioski;A. Beifiori;S. Belli;R. Be
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文献类型：
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作者：
P. Lang;N. F. Schreiber;R. Genzel;R. Genzel;S. Wuyts;E. Wisnioski;A. Beifiori;S. Belli;R. Be
我们利用来自KMOS3D和SINS/zC-SINF调查的深度，分辨率，Hα运动学数据来检查大部分未被探索的恒星形成星系（SFGs）的外盘运动学，直到宇宙恒星形成的高峰期。我们的样本包含101个sfg，代表了0.6≤z≤2.6的更大的（）主序列群体。通过一种新颖的叠加方法，我们能够约束延伸到~ 4有效半径的代表性旋转曲线。这条平均旋转曲线显示出旋转速度在翻转之后的显著下降，斜率为0，以标准化坐标V/Vmax和R/Rturn为单位。这一结果证实了在个别星系中看到的衰减是我们的高z盘样本的共同特征。外层的下降明显偏离了具有相似质量的本地螺旋星系的平坦或温和上升的旋转曲线。通过与包含重子和暗物质的模型的比较，我们证明了下降的堆叠旋转曲线与重子的高质量分数相一致，相对于总暗物质晕（md≥0.05），结合外盘相当大的压力支持。这些发现与最近的研究结果一致，这些研究表明，高z恒星形成盘在盘尺度内强烈以重子为主，并且进一步表明，由大的湍流气体运动引起的压力梯度甚至在它们的外盘中也存在。这些结果在很大程度上与我们的模型假设无关，比如恒星凸起的存在、绝热收缩的影响以及光晕浓度的变化。
We exploit the deep, resolved, Hα kinematic data from the KMOS3D and SINS/zC-SINF surveys to examine the largely unexplored outer-disk kinematics of star-forming galaxies (SFGs), out to the peak of cosmic star formation. Our sample contains 101 SFGs, representative of the more massive ( ) main sequence population at 0.6 ≤ z ≤ 2.6. Through a novel stacking approach, we are able to constrain a representative rotation curve extending out to ∼4 effective radii. This average rotation curve exhibits a significant drop in rotation velocity beyond the turnover, with a slope of in units of normalized coordinates V/Vmax and R/Rturn. This result confirms that the fall-off seen in some individual galaxies is a common feature of our sample of high-z disks. The outer fall-off strikingly deviates from the flat or mildly rising rotation curves of local spiral galaxies that have similar masses. Through a comparison with models that include baryons and dark matter, we demonstrate that the falling stacked rotation curve is consistent with a high mass fraction of baryons, relative to the total dark matter halo (md ≳ 0.05), in combination with a sizeable level of pressure support in the outer disk. These findings agree with recent studies demonstrating that high-z star-forming disks are strongly baryon-dominated within the disk scale, and furthermore suggest that pressure gradients caused by large, turbulent gas motions are present even in their outer disks. These results are largely independent of our model assumptions, such as the presence of stellar bulges, the effect of adiabatic contraction, and variations in halo concentration.