ALMA化学演化（ACE）巡天：概览——将尘埃与气体推断拓展至宇宙正午的低金属丰度

中文摘要 AI 辅助

重子循环支配着星系与其环境之间气体、金属和尘埃的交换，但在红移z>1之外，对这些组分的同时约束仍然稀缺。ALMA化学演化（ACE）巡天是ALMA第11周期的一项大型计划，旨在通过研究宇宙正午（cosmic noon）时期亚太阳金属丰度星系的分子气体、尘埃和金属含量来解决这一问题。ACE包含对25个位于z=2.0-2.5、具有可靠气相金属丰度测量（覆盖太阳金属丰度的约35%至83%）星系的CO(3-2)和尘埃连续谱观测。该巡天使具有CO、尘埃连续谱和金属丰度测量的z>1非透镜主序星系数量大约翻倍，并将此类研究扩展到比以往巡天低近一个数量级的恒星质量和金属丰度范围。ACE观测获得了17个CO探测和17个Band 7连续谱（静止系约270微米）探测。CO可探测性与金属丰度和恒星质量的相关性最强，而尘埃连续谱可探测性与恒星形成率（SFR）和红外光度联系更紧密。利用ACE测量数据，我们推导出一个新的经验标度关系，将CO(3-2)光度与恒星质量、SFR和金属丰度联系起来，为估算低质量、低金属丰度星系的分子气体含量提供了实用基准。该巡天揭示了一些特别引人注目的系统，包括目前已知z>1处金属丰度最低的CO和尘埃探测之一、具有极端气体和尘埃比例的星系，以及恒星、尘埃和分子气体发射之间存在偏移的系统。ACE首次提供了宇宙正午时期亚太阳金属丰度星系中分子气体、尘埃、金属和恒星形成之间相互作用的全面视图，使得在星系组装高峰时期直接检验重子循环、化学增丰和尘埃演化模型成为可能。

英文摘要

The baryon cycle governs the exchange of gas, metals, and dust between galaxies and their environments, but simultaneous constraints on these constituents remain scarce beyond z~1. The ALMA Chemical Evolution (ACE) survey is a Cycle 11 ALMA Large Program designed to address this by studying the molecular gas, dust, and metal content of sub-solar metallicity at cosmic noon. ACE consists of CO(3-2) and dust continuum observations of 25 galaxies at z=2.0-2.5 with robust gas-phase metallicity measurements spanning ~35% to 83% of solar metallicity. The survey approximately doubles the number of unlensed main-sequence galaxies at z>1 with CO, dust-continuum and metallicity measurements and extends such studies to almost an order of magnitude lower stellar masses and metallicities than previous surveys. The ACE observations yield 17 CO detections and 17 Band 7 continuum (rest-frame ~270um) detections. CO detectability correlates most strongly with metallicity and stellar mass, while dust continuum detectability is more closely linked to star formation rate (SFR) and infrared luminosity. Using the ACE measurements, we derive a new empirical scaling relation linking CO(3-2) luminosity to stellar mass, SFR, and metallicity, providing a practical benchmark for estimating molecular gas content in low-mass, low-metallicity galaxies. The survey reveals several particularly intriguing systems, including some of the lowest-metallicity CO and dust detections currently known at z>1, galaxies with extreme gas and dust fractions, and systems exhibiting offsets between stellar, dust, and molecular gas emission. ACE provides the first comprehensive view of the interplay between molecular gas, dust, metals, and star formation in sub-solar metallicity galaxies at cosmic noon, enabling direct tests of models for baryon cycling, chemical enrichment, and dust evolution during the peak epoch of galaxy assembly.

发表机构

• Centro de Astrobiología (CAB), CSIC-INTA（西班牙太空生物研究中心）
• European Southern Observatory（欧洲南方天文台）
• Leiden Observatory, Leiden University（莱顿大学莱顿天文台）
• Department of Astronomy, University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校天文学系）
• Department of Physics, University of California, Santa Barbara（加州大学圣塔芭芭拉分校物理系）
• Cosmic Dawn Center at the Niels Bohr Institute, University of Copenhagen and DTU-Space, Technical University of Denmark（哥本哈根大学尼尔斯·玻尔学院宇宙黎明中心及丹麦技术大学DTU空间）
• Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM（巴黎萨克雷大学、巴黎西岱大学、法国原子能和替代能源委员会、法国国家科学研究中心）
• Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天体物理学研究学院）
• Department of Physics and Astronomy（物理与天文学系）

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备注

Submitted to A&A. Part of the ACE survey series. This paper is one of several companion papers submitted to arXiv simultaneously; see also Langan et al., Popping et al., Solimano et al., Geesink et al