从ALMA观测中提取的跨M100（NGC 4321）棒、螺旋臂、臂间和核周区域的GMC缔合特性的变化
Variation in GMC Association Properties Across Bars, Spiral Arms, Inter-Arms, and Circumnuclear Region of M100 (NGC 4321) Extracted from ALMA Observations
摘要：
利用12 CO（1-0）的ALMA科学验证羽流（12-m+ACA）数据，研究了M100（NGC 4321）中巨分子云星协的物理性质.为了研究GMA性质的环境依赖性，GMA根据它们在各种环境中的位置进行分类，如环核环（CNR），酒吧，螺旋形和臂间GMA。CNR GMAs大而致密，而臂间GMAs弥散分布，表面密度低。正如Larson（1981）所指出的，GMA的质量和大小密切相关。然而，不同的幂律指数的关系意味着GMA属性是不均匀的环境之间。与其他环境相比，CNR和条形GMAs表现出更高的速度频散。我们发现几乎没有证据表明GMA速度色散和尺寸之间的相关性，这表明GMAs是在不同的动力学状态。实际上，GMA的维里参数跨越了近两个数量级。一般来说，只有螺旋形GM是自引力的。GMAs的恒星形成活动依次为CNR型、螺旋型、棒型和臂间GMAs。不同的GMA和恒星形成的性质在不同的环境中导致变化的肯尼库特-施密特关系。多种机制或气相变化的组合是必要的，以解释所观察到的斜率。还提出了与使用的12米阵列的观测与那些从羽状数据获得的GMA属性的比较。结果表明，在研究大气环境依赖性时，漏通量和扩展排放是不可忽略的。
英文摘要：
We study the physical properties of giant molecular cloud associations (GMAs) in M100 (NGC 4321) using the ALMA Science Verification feathered (12-m+ACA) data in 12CO (1-0). To examine the environmental dependence of GMA properties, GMAs are classified based on their locations in the various environments as circumnuclear ring (CNR), bar, spiral, and inter-arm GMAs. The CNR GMAs are massive and compact, while the inter-arm GMAs are diffuse with low surface density. GMA mass and size are strongly correlated, as suggested by Larson (1981). However, the diverse power-law index of the relation implies that the GMA properties are not uniform among the environments. The CNR and bar GMAs show higher velocity dispersion than those in other environments. We find little evidence for a correlation between GMA velocity dispersion and size, which indicates that the GMAs are in diverse dynamical states. Indeed, the virial parameter of GMAs spans nearly two orders of magnitude. Only the spiral GMAs are in general self-gravitating. Star formation activity of the GMAs decreases in order over the CNR, spiral, bar, and the inter-arm GMAs. The diverse GMA and star formation properties in different environments lead to variations in the Kennicutt-Schmidt relation. A combination of multiple mechanisms or gas phase change is necessary to explain the observed slopes. Comparisons of GMA properties acquired with the use of the 12-m-array observations with those from the feathered data are also presented. The results show that the missing flux and extended emission cannot be neglected for the study of environmental dependence.
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