[论文解读] High-redshift star formation in the ALMA era

Jacqueline Hodge, Elisabete da Cunha|arXiv (Cornell University)|Apr 2, 2020

Galaxies: Formation, Evolution, Phenomena参考文献 636被引用 33

一句话总结

ALMA 通过提供前所未有的分辨率、灵敏度和光谱能力，显著推进了高红移尘埃遮蔽的恒星形成研究，能够实现精确定位、分辨的 ISM 研究，并探测超越经典 SMG 的更暗淡星系群体。

ABSTRACT

The Atacama Large Millimetre/submillimetre Array (ALMA) is currently in the process of transforming our view of star-forming galaxies in the distant ($z\gtrsim1$) universe. Before ALMA, most of what we knew about dust-obscured star formation in distant galaxies was limited to the brightest submillimetre sources$-$the so-called submillimetre galaxies (SMGs)$-$and even the information on those sources was sparse, with resolved (i.e., sub-galactic) observations of the obscured star formation and gas reservoirs typically restricted to the most extreme and/or strongly lensed sources. Starting with the beginning of early science operations in 2011, the last nine years of ALMA observations have ushered in a new era for studies of high-redshift star formation. With its long baselines, ALMA has allowed observations of distant dust-obscured star formation with angular resolutions comparable to$-$or even far surpassing$-$the best current optical telescopes. With its bandwidth and frequency coverage, it has provided an unprecedented look at the associated molecular and atomic gas in these distant galaxies through targeted follow-up and serendipitous detections/blind line scans. Finally, with its leap in sensitivity compared to previous (sub-)millimetre arrays, it has enabled the detection of these powerful dust/gas tracers much further down the luminosity function through both statistical studies of color/mass-selected galaxy populations and dedicated deep fields. We review the main advances ALMA has helped bring about in our understanding of the dust and gas properties of high-redshift ($z\gtrsim1$) star-forming galaxies during these first nine years of its science operations, and we highlight the interesting questions that may be answered by ALMA in the years to come.

研究动机与目标

• 评估 ALMA 的能力如何改变对高红移星系（z > 1）中尘埃遮蔽恒星形成的观测。
• 综述 ALMA 在亚毫米选星的星系（SMGs）和强透镜系统方面的进展。
• 总结遥远恒星形成星系的统计与分辨的 ISM 属性。
• 讨论 ALMA 调查与后续观测如何扩展光度函数和红移覆盖范围。

提出的方法

• 描述 ALMA 的关键能力：角分辨率、频率覆盖、带宽和灵敏度。
• 解释 ALMA 如何实现对 SMGs 的精确定位和对应体识别。
• 概述解决高-z 来源多重性和透镜效应的方法。
• 概述 ALMA 调查（盲检与靶向）如何约束遥远星系中的气体含量和尘埃性质。

实验结果

研究问题

• RQ1 ALMA 如何改变定位和识别在亚毫米观测中发现的远距离尘埃遮蔽恒星形成星系的对应体的能力？
• RQ2 ALMA 观测揭示了高 redshift 银河中的 ISM 属性、气体分数和恒星形成规律。
• RQ3 强透镜系统和 ALMA 的盲检调查在多大程度上改变了我们对高-z 尘埃星系群体和宇宙气体密度的理解？
• RQ4 什么界定了 ALMA 时代的 SMG 群体，以及它如何与颜色与质量选取的高-z 银河相联系？

主要发现

• ALMA 提供对 SMGs 的亚秒级定位，使得对应体识别和红移估计精确。
• ALMA 解决单口径 SMG 来源中的多重性，揭示在先前波束内的多个亚毫米星系。
• ALMA 的调查与后续观测能力揭示高-z 银河的尘埃/气体性质，包括分辨的 ISM 与动力学。
• 深度 ALMA 观测使探测更暗淡的星系成为可能，将研究扩展到超出经典 SMG 的光度函数下方。
• ALMA 的光谱能力通过多条分子和原子线实现红移确认和详细的 ISM 研究。
• 使用 ALMA 的透镜效应与源重建技术提高对高-z ISM 物理和本征源属性的测量。