ALMA化学演化（ACE）巡天：宇宙正午亚太阳金属丰度星系中的尘埃与气体比
ALMA Chemical Evolution (ACE) survey: dust-to-gas ratios in sub-solar metallicity galaxies at cosmic noon
- European Southern Observatory（欧洲南方天文台）
- Leiden Observatory, Leiden University（莱顿大学莱顿天文台）
- Centre for Astrobiology, Madrid（马德里天体生物学中心）
- Department of Astronomy, University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校天文学系）
- Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文学与天体物理学研究学院）
- Department of Physics and Astronomy, University of California, Riverside（加州大学河滨分校物理与天文学系）
- Department of Astronomy, University of Florida（佛罗里达大学天文学系）
- 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·玻尔研究所宇宙黎明中心及丹麦技术大学DTU空间部）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
基于ALMA化学演化巡天，测量宇宙正午亚太阳金属丰度星系的尘埃与分子气体比，发现其随金属丰度增加而增加，为尘埃增丰模型提供新约束。
AI中文摘要：
尘埃是星际介质的基本组成部分，也是调节星系演化的重子循环的关键示踪剂。尘埃与气体之比将气相中的金属与锁定在尘埃颗粒中的金属联系起来，使其成为尘埃产生、颗粒增长和破坏的敏感诊断指标。我们基于ALMA化学演化（ACE）巡天，在红移z≃2-2.5处，对亚太阳金属丰度、典型恒星形成星系（log M⋆ ≈ 10）呈现了尘埃与分子气体之比（DGR_mol）的测量结果。通过将ALMA CO和尘埃连续谱观测与稳健的气相金属丰度测量相结合，ACE将直接尘埃和分子气体测量扩展到该时代先前可用的更低恒星质量和更低金属丰度，最低可达0.4 Z⊙。这首次为宇宙正午典型未透镜星系提供了DGR_mol-金属丰度关系的约束。我们发现DGR_mol随金属丰度增加而增加，对数空间斜率为1.2 ± 0.7，表明贫金属星系的DGR_mol系统性地低于其金属丰度更高的对应星系。对于探测到的ACE星系，我们测得平均log10(M_dust/M_mol) = -2.37 ± 0.05，对应平均金属丰度12+log(O/H) = 8.45 ± 0.02。我们发现与局部宇宙在固定金属丰度下的DGR_mol一致，表明在宇宙正午，金属丰度8.3 ≤ 12+log(O/H) ≤ 8.7范围内，相同的尘埃增长物理机制（很可能是星际介质中的颗粒增长）占主导地位。这些测量为宇宙恒星形成峰值时期尘埃增丰和星系演化模型提供了新颖的经验约束。此外，ACE为将尘埃连续谱作为分子气体示踪剂的校准提供了亚太阳金属丰度参考，这对于研究贫金属、高红移系统至关重要。
英文摘要：
Dust is a fundamental component of the interstellar medium and provides a key tracer of the baryon cycle that regulates galaxy evolution. The dust-to-gas ratio links metals in the gas phase to those locked into dust grains, making it a sensitive diagnostic of dust production, grain growth, and destruction. We present measurements of the dust-to-molecular-gas ratio ($\rm DGR_{mol}$), for typical star-forming galaxies ($\log M_\star \approx 10$) at sub-solar metallicites, at $z\simeq2-2.5$ from the ALMA Chemical Evolution (ACE) survey. By combining ALMA CO and dust-continuum observations with robust gas-phase metallicity measurements, ACE extends direct dust and molecular-gas measurements to lower stellar masses and lower metallicities than previously available at this epoch, reaching down to $0.4\,Z_{\odot}$. This enables the first constraints on the $\rm DGR_{mol}$--metallicity relation for typical unlensed galaxies at cosmic noon. We find that $\rm DGR_{mol}$ increases with metallicity, with a log-space slope of $1.2 \pm 0.7$, indicating that metal-poor galaxies have systematically lower $\rm DGR_{mol}$ than their more metal-rich counterparts. For the detected ACE galaxies, we measure a mean value of $\log_{10}(M_{\rm dust}/M_{\rm mol})=-2.37\pm0.05$ for a mean metallicity of 12+$\log (\rm O/H) = 8.45 \pm 0.02$. We find agreement with $\rm DGR_{mol}$ in the local Universe at fixed metallicities, indicating that the same dust-growth physics, likely grain growth in the ISM, dominates at metallicities of $8.3 \leq 12+\log(\rm O/H) \leq 8.7$ at cosmic noon. These measurements provide novel empirical constraints for models of dust enrichment and galaxy evolution during the peak epoch of cosmic star formation. Additionally, ACE provides a sub-solar metallicity reference for the calibration of dust continuum as tracer of molecular gas, essential for studying metal-poor, high-redshift systems.
