ATLASGAL：银河系的HCN-红外恒星形成关系
ATLASGAL: The HCN-IR Star Formation Relation for the Milky Way
- University of Kent（肯特大学）
- Max-Planck-Institut für Radioastronomie (MPIfR)（马克斯·普朗克射电天文研究所）
- Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS（波尔多天体物理实验室，波尔多大学，法国国家科学研究中心）
- Institute of Advanced Studies, Nicolaus Copernicus University in Toruń（尼古拉·哥白尼大学托伦高等研究院）
- INAF - Istituto di Radioastronomia（意大利国家天体物理研究所射电天文分部）
- Argelander-Institut für Astronomie, University of Bonn（波恩大学阿尔兰德天文学研究所）
- Department of Physics, University of Bath（巴斯大学物理系）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用343个银河系团块样本，发现HCN-红外关系斜率比河外星系更陡，且致密团块仅贡献少量光度，表明近邻星系的线性关系源于平均恒星形成效率，而非SFR与致密气体的直接关联。
AI中文摘要：
我们利用HCN(1-0)谱线示踪的致密气体，研究了恒星形成与致密气体之间的关系。样本包含343个银河系团块，涵盖了代表高质量恒星和星团形成的完整演化阶段，包括静默、原恒星、年轻恒星天体（YSO）和HII区。早期的银河系研究主要基于明亮HII区，报道了红外（IR）与HCN光度之间的线性相关性，这与河外星系巡天一致，并被解释为普遍的恒星形成规律。我们更大的演化样本给出了显著更陡的斜率$1.80\pm0.08$，与河外星系趋势不一致。然而，我们发现每个恒星形成演化阶段单独来看，其斜率（$\sim$1.2）都比全样本更平缓，而静默团块则没有相关性。我们通过积分Hi-GAL源的辐射光度和团块质量，估算了银河系致密团块的总红外和HCN光度。两者都显著低于河外星系的值，表明仅团块无法解释IR-HCN关系。银河系HCN光度中只有约5-25%来自致密团块，这意味着大多数河外星系HCN示踪的气体并未参与恒星形成。此外，致密团块仅贡献银河系红外光度的约2-3%，而红外光度主要由延伸的HII区和PDR主导，它们示踪了更长的恒星形成时标。因此，在近邻星系中观测到的线性关系反映的是在大面积和长时间尺度上平均的近恒定恒星形成效率，而不是SFR与致密气体质量之间的直接联系。
英文摘要：
We examine the relation between star formation and dense gas, traced by HCN(1-0), using a sample of 343 Galactic clumps spanning the full range of evolutionary stages representative of high-mass and cluster formation, including quiescent, protostellar, young stellar object (YSO), and HII regions. Earlier Galactic studies, based primarily on luminous HII regions, reported a linear correlation between infrared (IR) and HCN luminosities, consistent with extragalactic surveys, and interpreted it as a universal star formation law. Our larger evolutionary sample yields a significantly steeper slope of $1.80\pm0.08$, inconsistent with extragalactic trends. However, we find that each of the star-forming evolutionary stages individually has a shallower slope ($\sim$1.2) than that of the full sample, with quiescent clumps showing no correlation. We estimate the Milky Way's total IR and HCN luminosities from dense clumps by integrating the bolometric luminosities and clump masses of Hi-GAL sources. Both fall significantly below extragalactic values, demonstrating that clumps alone cannot account for the IR-HCN relation. Only $\sim$5-25 per cent of Galactic HCN luminosity arises from dense clumps, implying that most extragalactic HCN traces gas that is not involved in star formation. Additionally, dense clumps contribute only $\sim$2-3 per cent of the Milky Way's IR luminosity, which is dominated instead by extended HII regions and PDRs tracing longer star formation timescales. As a result, the observed linear relation in nearby galaxies reflects a nearly constant star formation efficiency averaged over large areas and long timescales, rather than a direct link between SFR and dense gas mass.
