发表机构
Centro de Astrobiología (CAB), CSIC-INTA; European Southern Observatory; Leiden Observatory, Leiden University; Department of Astronomy, University of Massachusetts, Amherst; Departamento de Física de la Tierra y Astrofísica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid; Department of Physics and Astronomy, University of California, Riverside; Department of Astronomy, University of Florida（天体生物学中心; 欧洲南方天文台; 莱顿大学天文台; 马萨诸塞大学阿默斯特分校天文学系; 马德里康普顿斯大学物理科学学院地球与天体物理学系; 加州大学河滨分校物理与天文学系; 佛罗里达大学天文学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究利用 ALMA 观测 25 个 z~2.3 的亚太阳金属丰度星系，发现其尘埃质量比同金属丰度、同恒星质量的近邻星系高 3-9 倍，且 DtS 比值与 sSFR 正相关，表明分子气体比例驱动了尘埃过量。
AI 中文摘要
尘埃通过影响恒星形成和塑造星系的观测光谱，在星系演化中扮演着关键角色。然而，在 z~2（宇宙正午）时期，我们对尘埃质量预算的认识目前仅限于质量最大、金属丰度最高的系统，这些系统并不能代表星系群体的主体。在此，我们通过测量来自 ALMA 化学演化（ACE）大型巡天项目中 z~2.3 的 25 个星系的尘埃质量，来探索较低质量、亚太阳金属丰度的星系。该样本包含 COSMOS 场中的恒星形成星系，其强线金属丰度测量可靠，低至约 0.3 个太阳金属丰度（$Z_\odot$）。利用在 873 微米或 1.3 毫米处探测到的尘埃连续谱辐射，我们假设光学薄、单温度修正黑体模型来约束尘埃质量。得到的尘埃质量平均为 $10^{8}\\,\mathrm{M}_\odot$，比在匹配金属丰度和恒星质量条件下 z=0 的星系大三到九倍。我们还发现尘埃质量与恒星质量、金属丰度和恒星形成率（SFR）之间存在正相关。相反，我们发现 $M_\mathrm{dust}/M_\mathrm{stars}$（DtS）比值在 $10^{-2.2}$ 附近弥散，但未显示与金属丰度相关的证据。这一结果与尘埃演化模型一致，该模型预测一旦星际介质达到临界金属丰度，DtS 将保持恒定，此时金属在尘埃颗粒上的吸积成为尘埃增长的主要方式。$M_\mathrm{dust}/\mathrm{SFR}$ 与金属丰度之间的相关性也表明 ACE 星系已经超过了临界金属丰度。最后，我们发现 DtS 比值与比恒星形成率（sSFR）相关。由于 sSFR 较高（$> 10^{-8}\\,\mathrm{yr}^{-1}$），这解释了相对于 z~0 星系的 DtS 超出。反过来，sSFR 和 DtS 很可能都由分子气体比例驱动，这一点得到了作为 ACE 一部分进行的 CO(3-2) 测量的支持。
英文摘要
Dust plays a key role in galaxy evolution by influencing star formation and shaping the observed spectrum of galaxies. However, at z~2 (cosmic noon) our knowledge of the dust mass budget is currently limited to the most massive, metal-rich systems, which are not representative of the bulk galaxy population. Here, we probe the lower mass, subsolar metallicity regime by measuring the dust mass of 25 galaxies at z~2.3 from the ALMA Chemical Evolution (ACE) Large Program. The sample contains star-forming galaxies in the COSMOS field with robust strong-line metallicities down to ~0.3 $Z_\odot$. Using the dust continuum emission detected at 873micron or 1.3mm we constrain the dust mass by assuming an optically thin single-temperature modified blackbody. The resulting dust masses average $10^{8}\,\mathrm{M}_\odot$, and they are three to nine times larger than those of z=0 galaxies at a matched metallicity and stellar mass. We also find positive correlations between dust mass and stellar mass, metallicity, and star formation rate (SFR). In contrast, we find that the $M_\mathrm{dust}/M_\mathrm{stars}$ (DtS) ratio scatters around $10^{-2.2}$ but shows no evidence of correlation with metallicity. This result is consistent with dust evolution models that predict a constant DtS once the ISM reaches the critical metallicity, at which metal accretion onto grains becomes the main mode of dust buildup. The correlation between $M_\mathrm{dust}/\mathrm{SFR}$ and metallicity also suggest that ACE galaxies have already surpassed the critical metallicity. Finally, we find that the DtS ratio is correlated to the specific SFR (sSFR). Since the sSFR are high ($> 10^{-8}\,\mathrm{yr}^{-1}$) this explains the DtS excess over z~0 galaxies. In turn, both sSFR and DtS are likely driven by the molecular gas fraction, as supported by CO(3-2) measurements taken as part of ACE.
CommentsSubmitted to A&A. Part of the ACE survey series. This paper is one of several companion papers submitted to arXiv simultaneously; see also Geesink et al., Langan et al., Popping et al., and Shivaei et al
