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arXiv 1107.4367astro-ph.CO
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z~2-3成星星系中Ly-alpha发射的多峰动力学

The Kinematics of Multiple-Peaked Ly-alpha Emission in Star-Forming Galaxies at z~2-3

Kristin R. Kulas, Alice E. Shapley, Juna A. Kollmeier, Zheng Zheng, Charles C. Steidel, Kevin N. Hainline

摘要:

本文给出了18个具有多峰Ly-alpha轮廓的z~2-3恒星形成星系的Ly-alpha发射线运动学的新结果。我们的大型光谱数据库的紫外线选择的恒星形成星系在这些红移,我们已经确定,约30%的这样的对象与可检测的Ly-alpha发射显示多峰的发射轮廓。这些配置文件提供了额外的限制逃逸的Ly-alpha光子,由于丰富的速度结构的出射线。尽管最近在模拟Ly-alpha从恒星形成星系中逃逸的高红移方面取得了进展,但模型和数据之间的比较往往缺少关键的观测信息。使用H-alpha(z~2)和[OIII] 5007(z~3)的Keck II NIRSPEC光谱,我们测量了样本中物体的准确系统红移、静止框架光学星云速度色散和发射线通量。精确的系统红移使我们能够将多峰Ly-alpha分布转化为速度空间,揭示了大多数(11/18)显示双峰发射跨越速度场零点,具有更强的红边发射。我们将我们的数据与高红移星系周围流出和下落气体分布的简单模型的预测进行比较。虽然流行的“壳”模型提供了一个定性的匹配与许多观测的Ly-alpha发射,我们发现,在细节上有重要的差异之间的模型和数据,以及问题的应用框架的膨胀薄壳的气体来解释高红移星系光谱。我们的数据突出了这些不一致性,以及在未来的高红移星系外流和流入模型中成功的关键因素。[摘要]

英文摘要:

We present new results on the Ly-alpha emission-line kinematics of 18 z~2-3 star-forming galaxies with multiple-peaked Ly-alpha profiles. With our large spectroscopic database of UV-selected star-forming galaxies at these redshifts, we have determined that ~30% of such objects with detectable Ly-alpha emission display multiple-peaked emission profiles. These profiles provide additional constraints on the escape of Ly-alpha photons due to the rich velocity structure in the emergent line. Despite recent advances in modeling the escape of Ly-alpha from star-forming galaxies at high redshifts, comparisons between models and data are often missing crucial observational information. Using Keck II NIRSPEC spectra of H-alpha (z~2) and [OIII] 5007 (z~3), we have measured accurate systemic redshifts, rest-frame optical nebular velocity dispersions and emission-line fluxes for the objects in the sample. Accurate systemic redshifts allow us to translate the multiple-peaked Ly-alpha profiles into velocity space, revealing that the majority (11/18) display double-peaked emission straddling the velocity-field zeropoint with stronger red-side emission. We compare our data with the predictions of simple models for outflowing and infalling gas distributions around high-redshift galaxies. While popular "shell" models provide a qualitative match with many of the observations of Ly-alpha emission, we find that in detail there are important discrepancies between the models and data, as well as problems with applying the framework of an expanding thin shell of gas to explain high-redshift galaxy spectra. Our data highlight these inconsistencies, as well as illuminating critical elements for success in future models of outflow and infall in high-redshift galaxies. [Abridged]

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