量化PHANGS-HST星团周围CO(2-1)强度的下降：对分子气体消散、恒星反馈和星团形成效率的约束
Quantifying the decline in CO(2-1) intensity around PHANGS-HST star clusters: Constraints on molecular gas dispersal, stellar feedback, and cluster formation efficiency
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中文总结 AI 辅助
本研究结合PHANGS-HST和PHANGS-ALMA数据，分析29,233个星团，发现CO强度随星团年龄和质量下降，早期恒星反馈是星团与分子气体分离的主要驱动因素，星团形成效率约1.2%。
中文摘要 AI 辅助
我们将迄今最大的近邻星系星团巡天PHANGS-HST与来自PHANGS-ALMA的分子气体图谱相结合，以约束星团形成的效率以及星团与其诞生分子气体分离的典型时标。我们利用150 pc分辨率的CO图谱分析了36个星系中的29,233个星团。对于每个恒星质量≥10^3.5 M_sun的星团，我们测量了CO(2-1)积分强度的径向轮廓，并获得了星团中心处经局部背景扣除的CO强度I_CO^bkgsub。我们按年龄和质量对星团进行分组，以量化I_CO^bkgsub和相应的分子气体质量M_mol对这些星团性质的依赖。为了考虑星团质量M_SC的依赖性，我们还计算了归一化的质量比(M_mol/M_SC)。我们发现CO强度随星团年龄和质量系统性变化。与Hα发射空间关联的星团表现出最高的I_CO^bkgsub，为7.4 K km s^-1，对应的M_mol/M_SC比为82，这意味着星团形成效率ε_obs约为1.2%。没有关联Hα发射的年轻星团表现出较低且依赖于年龄的I_CO^bkgsub和M_mol/M_SC，从年龄1-3 Myr星团的1.3 K km s^-1和15，下降到年龄大于9-10 Myr星团的约0水平。年龄大于10 Myr的星团没有表现出统计上显著的CO强度超出。我们使用与Hα关联的星团作为初始条件来模拟星团漂移的影响，并证明这不太可能在4-6 Myr的短时标内驱动观测到的星团-气体空间分离。相反，早期恒星反馈似乎是主要驱动因素。
英文摘要
We combine the largest survey of star clusters in nearby galaxies to-date, PHANGS-HST, with maps of molecular gas maps from PHANGS-ALMA to constrain the efficiency of cluster formation and the typical timescales over which clusters become dis-associated from their natal molecular gas. We analyse 29,233 clusters in 36 galaxies using CO maps at 150 pc resolution. For each star cluster with stellar mass $\geq 10^{3.5}$ M$_\odot$, we measure the radial profiles of CO(2-1) integrated intensity and obtain local background-subtracted CO intensity, $I_{\rm CO}^{\rm bkgsub}$, at cluster centre. We group the clusters by age and mass to quantify the dependence of $I_{\rm CO}^{\rm bkgsub}$ and corresponding molecular gas mass, $M_{\rm mol}$, on these cluster properties. To account for the cluster mass ($M_{\rm SC}$) dependence, we also calculate the normalised mass ratio of $(M_{\rm mol}/M_{\rm SC})$. We find that CO intensity varies systematically with cluster age and mass. Clusters that are spatially associated with H$α$ emission exhibit the highest $I_{\rm CO}^{\rm bkgsub}$ of 7.4 K km s$^{-1}$, corresponding to a $M_{\rm mol}/M_{\rm SC}$ ratio of 82 and implying a cluster formation efficiency ($ε_{\rm obs}$) of $\sim 1.2\%$. Young clusters without associated H$α$ emission show lower and age-dependent $I_{\rm CO}^{\rm bkgsub}$ and $M_{\rm mol}/M_{\rm SC}$, decreasing from 1.3 K km s$^{-1}$ and 15 for clusters with age 1-3 Myr, to a level $\approx$ 0 for clusters older than 9--10 Myr. Clusters older than 10 Myr show no statistical excess of CO intensity. We use the clusters with H$α$ association as initial conditions to model the impact of cluster drift and demonstrate that this is unlikely to drive the observed cluster-gas spatial disassociation on short timescales of 4-6 Myr. Instead, early stellar feedback seems likely to be the main driver.
发表机构
- Universität Bonn（波恩大学）
- University of Cologne（科隆大学）
- The Ohio State University（俄亥俄州立大学）
- University of Alberta（阿尔伯塔大学）
- Space Telescope Science Institute（太空望远镜科学研究所）
- The Johns Hopkins University（约翰斯·霍普金斯大学）
- University of Wyoming（怀俄明大学）
- Université de Toulouse（图卢兹大学）
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