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arXiv 0706.2656astro-ph
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z~2星形成星系团的动力学性质和一个普遍的恒星形成关系

Dynamical Properties of z~2 Star Forming Galaxies and a Universal Star Formation Relation

N. Bouche, G. Cresci, R. Davies, F. Eisenhauer, N. M. Forster Schreiber, R. Genzel, S. Gillessen, M. Lehnert, D. Lutz, N. Nesvadba, K. L. Shapiro, A. Sternberg,… 展开作者

N. Bouche, G. Cresci, R. Davies, F. Eisenhauer, N. M. Forster Schreiber, R. Genzel, S. Gillessen, M. Lehnert, D. Lutz, N. Nesvadba, K. L. Shapiro, A. Sternberg, L. J. Tacconi, A. Verma, A. Cimatti, E. Daddi, A. Renzini, D. K. Erb, A. Shapley, C. C. Steidel

摘要:

首次比较了来自SINFONI/VLT积分场光谱和IRAM CO毫米波干涉的空间分辨成像光谱对z~1.4-3.4恒星形成星系不同样本的动力学性质的影响。我们的样本包括16个静止帧紫外选择,16个静止帧光学选择和13个亚毫米星系(SMG)。我们发现,restframe紫外和光学亮(K<20)z~2恒星形成星系的动力学相似,并遵循相同的速度-尺寸关系的盘星系在z~0。在暗物质晕中耗散坍缩形成的旋转盘的理论框架中,这两个样品需要的自旋参数范围为0.06至0.2。相比之下,明亮的SMG具有更大的速度宽度,并且更加紧凑。因此,SMG具有较低的角动量和较高的物质密度比任何紫外线或光学选择的人口。这表明耗散的主要合并可能主导SMG人口,导致早期的球状体,并且大多数UV/光学明亮的星系演化不那么激烈[.]。这些早期的盘可能后来通过盘的不稳定性或合并演化成球状体。由于它们的小尺寸和大密度,SMG位于气体表面密度和恒星形成率表面密度之间的普遍(z=2.5)“施密特-肯尼库特”关系的高表面密度端,斜率约为1.7。

英文摘要:

We present the first comparison of the dynamical properties of different samples of z~1.4-3.4 star forming galaxies from spatially resolved imaging spectroscopy from SINFONI/VLT integral field spectroscopy and IRAM CO millimeter interferometry. Our samples include 16 rest-frame UV-selected, 16 rest-frame optically-selected and 13 submillimeter galaxies (SMGs). We find that restframe UV- and optically bright (K<20) z~2 star forming galaxies are dynamically similar, and follow the same velocity-size relation as disk galaxies at z~0. In the theoretical framework of rotating disks forming from dissipative collapse in dark matter halos, the two samples require a spin parameter ranging from 0.06 to 0.2. In contrast bright SMGs have larger velocity widths and are much more compact. Hence, SMGs have lower angular momenta and higher matter densities than either of the UV- or optically selected populations. This indicates that dissipative major mergers may dominate the SMGs population, resulting in early spheroids, and that the majority of UV/optically bright galaxies have evolved less violently [...]. These early disks may later evolve into spheroids via disk instabilities or mergers. Because of their small sizes and large densities, SMGs lie at the high surface density end of a universal (out to z=2.5) "Schmidt-Kennicutt" relation between gas surface density and star formation rate surface density with a slope of ~1.7.

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