发表机构
Purple Mountain Observatory and Key Laboratory of Radio Astronomy, Chinese Academy of Sciences; School of Astronomy and Space Science, University of Science and Technology of China（中国科学院紫金山天文台射电天文重点实验室; 中国科学技术大学天文与空间科学学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
基于第二银象限CO巡天数据，识别2912个分子云，发现4型标度关系受压缩性影响，结构复杂性由引力而非湍流主导，支持引力调控的层级动力学图像。
AI 中文摘要
我们基于银河系成像滚动绘画巡天的高灵敏度12CO和13CO J=1-0数据，对银河系银道面第二象限（139.75度≤l≤159.75度，-5.25度≤b≤8.25度）中分子云的层级结构进行了统计研究。利用DBSCAN和非二值树状图算法，我们识别出2,912个13CO云。2型（多云、单示踪剂）标度关系显示出随旋臂变化的趋势：线宽-尺度关系的幂律指数在本地臂约为0.32，在英仙臂和外臂约为0.42。经典的Keto-Heyer关系在本地臂较弱，但在英仙臂和外臂存在，斜率约为0.3。维里参数与云尺度、质量和面密度呈反相关，与之前的巡天结果一致。4型（单云、单示踪剂）标度关系表现出更强的内部相关性。线宽-尺度指数范围约为0.3-0.8，并与声速马赫数正相关，表明该关系并非普适，而是依赖于云的压缩性。虽然子结构不遵循基于面密度的传统Keto-Heyer关系，但体积密度公式恢复了清晰的维里标度，演化轨迹沿恒定维里参数的线排列。此外，分子云的结构复杂性（以子结构数量与min_delta参数之间的关系为特征）与面密度相关，而非声速马赫数，这与仅考虑湍流的磁流体动力学模拟结果相反。综合来看，这些结果更符合引力调控的层级动力学图像，而非纯湍流支撑的图景。
英文摘要
We present a statistical study of the hierarchical structure of molecular clouds in the second quadrant of the Galactic midplane (139.75 deg <= l <= 159.75 deg, -5.25 deg <= b <= 8.25 deg), based on high-sensitivity 12CO and 13CO J = 1-0 data from the Milky Way Imaging Scroll Painting survey. Using DBSCAN and a non-binary Dendrogram algorithm, we identify 2,912 13CO clouds. Type 2 (multicloud, single-tracer) scaling relations show arm-dependent trends: the power-law index of the linewidth-size relation is about 0.32 in the Local Arm and about 0.42 in the Perseus and Outer Arms. The classical Keto-Heyer relation is weak in the Local Arm but present in the Perseus and Outer Arms, with a slope of about 0.3. The virial parameter is anti-correlated with cloud size, mass, and surface density, consistent with previous surveys. Type 4 (single-cloud, single-tracer) scaling relations exhibit stronger internal correlations. The linewidth-size index spans about 0.3-0.8 and correlates positively with sonic Mach number, indicating that the relation is not universal but depends on cloud compressibility. While substructures do not follow the conventional surface-density-based Keto-Heyer relation, a volume-density formulation restores a clear virial scaling, with evolutionary tracks aligning along lines of constant virial parameter. Moreover, the structural complexity of molecular clouds, characterized by the relationship between the number of substructures and the min_delta parameter, correlates with surface density rather than sonic Mach number, contrary to results from turbulence-only magnetohydrodynamic simulations. Together, these results are more consistent with a gravity-regulated hierarchical dynamical picture than with a purely turbulence-supported scenario.
Comments27 pages, 18 figures, accepted by ApJ
