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arXiv 0901.2930astro-ph.GAastro-ph.CO
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高红移成星星系团的千秒尺度动力学

The Kiloparsec-Scale Kinematics of High-Redshift Star-Forming Galaxies

David R. Law, Charles C. Steidel, Dawn K. Erb, James E. Larkin, Max Pettini, Alice E. Shapley, Shelley A. Wright

摘要:

本文介绍了用Keck/OSIRIS积分场光谱法对红移z ~ 2 - 3的恒星形成星系的运动学结构进行的光谱测量结果。我们的样本是由12个星系之间的红移z ~ 2.0和2.5和一个星系在z ~ 3.3,这是很好地检测到无论是HAlpha或[O III]发射。这些观测是结合凯克激光导星自适应光学系统获得的,空间平滑后的典型角分辨率约为0.15”(在目标样品的红移处约为1 kpc)。在这13个星系中,最多有5个具有与旋转一致的空间分辨速度梯度,而其余的星系具有相对无特征或不规则的速度场。我们所有的星系都显示出约60 - 100 km/s的局部速度色散,这表明(特别是对于那些没有特征的速度场的星系)围绕优选轴的旋转可能不是物理支持的主要机制。虽然一些星系显示出重大合并的证据,但这些证据与单个组件的运动学无关(我们最强的合并候选者之一也表现出明确的旋转结构),驳斥了简单的双峰盘/合并分类方案。我们根据补充巡天和现存的紫外-红外光谱学和光度学对这些数据进行了讨论,得出结论:冷气体的动力学重要性可能是控制z ~ 2星系观测到的运动学的主要因素。最后,我们推测吸积低角动量气体和准球状系统在年轻宇宙的早期形成的机制的重要性。(节略)

英文摘要:

We present the results of a spectroscopic survey of the kinematic structure of star-forming galaxies at redshift z ~ 2 - 3 using Keck/OSIRIS integral field spectroscopy. Our sample is comprised of 12 galaxies between redshifts z ~ 2.0 and 2.5 and one galaxy at z ~ 3.3 which are well detected in either HAlpha or [O III] emission. These observations were obtained in conjunction with the Keck laser guide star adaptive optics system, with a typical angular resolution after spatial smoothing ~ 0.15" (approximately 1 kpc at the redshift of the target sample). At most five of these 13 galaxies have spatially resolved velocity gradients consistent with rotation while the remaining galaxies have relatively featureless or irregular velocity fields. All of our galaxies show local velocity dispersions ~ 60 - 100 km/s, suggesting that (particularly for those galaxies with featureless velocity fields) rotation about a preferred axis may not be the dominant mechanism of physical support. While some galaxies show evidence for major mergers such evidence is unrelated to the kinematics of individual components (one of our strongest merger candidates also exhibits unambiguous rotational structure), refuting a simple bimodal disk/merger classification scheme. We discuss these data in light of complementary surveys and extant UV-IR spectroscopy and photometry, concluding that the dynamical importance of cold gas may be the primary factor governing the observed kinematics of z ~ 2 galaxies. We conclude by speculating on the importance of mechanisms for accreting low angular-momentum gas and the early formation of quasi-spheroidal systems in the young universe.(abridged)

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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