发表机构
School of Astronomy and Space Science, Nanjing University; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education; South-Western Institute for Astronomy Research, Yunnan University（南京大学天文与空间科学学院; 现代天文学和天体物理学教育部重点实验室（南京大学）; 云南大学西南天文研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过密度指数分析猎户座A整体形状纤维，发现其密度结构呈多重分形标度，斜率从静止区到恒星形成区逐渐变陡，揭示重力驱动的差异坍缩过程。
AI 中文摘要
分子云常被描述为自相似结构，尽管空间平均测量无法保留密度标度中的局部变化。我们使用密度指数 $\kappa_\rho$（$\rho \propto r^{\kappa_\rho}$）来表征猎户座A中整体形状纤维（ISF）的密度结构。将多尺度分解重建方法应用于赫歇尔柱密度图，我们发现相连纤维中存在不同的密度-尺度关系。其斜率从静止的OMC-4/5区域中的 $\kappa_\rho \approx -1.7$ 到 $-1.9$，经过恒星形成区OMC-2/3中的 $\approx -2.1$，再到拥有大质量恒星形成的OMC-1中的 $\approx -2.3$，逐渐变陡。因此，ISF并不遵循单一的局部密度标度指数，而是表现出多重分形密度标度。像素级分布显示出同样的趋势，即向更高体积密度和更负的 $\kappa_\rho$ 发展。由于 $\kappa_\rho$ 衡量气体向更小尺度的集中程度，我们将这一序列解释为重力驱动的差异坍缩：较致密区域具有更短的自自由落体时间，并形成更陡的密度轮廓。朝向OMC-1的纵向气体运动可能限制了外部子区域大规模增长的质量供应，并有助于维持观测到的局部指数范围。这些结果将局部密度标度与单个相连纤维系统内的引力集中联系起来。
英文摘要
Molecular clouds are often described as self-similar structures, although spatially averaged measures do not retain local variations in density scaling. We use the density exponent $κ_ρ$ ($ρ\propto r^{κ_ρ}$) to characterize the density structure of the Integral Shaped Filament (ISF) in Orion\,A. Applying the Multiscale Decomposition Reconstruction method to the Herschel column-density map, we find distinct density--scale relations across the connected filament. Their slopes steepen from $κ_ρ\approx -1.7$ to $-1.9$ in the quiescent OMC-4/5 regions, through $\approx -2.1$ in the star-forming OMC-2/3, to $\approx -2.3$ in OMC-1, which hosts massive star formation. The ISF therefore does not follow a single local density-scaling exponent but exhibits multi-fractal density scaling. The pixel-level distributions show the same progression toward higher volume density and more negative $κ_ρ$. Since $κ_ρ$ measures the concentration of gas toward smaller scales, we interpret this sequence as gravity-driven differential collapse: denser regions have shorter free-fall times and develop steeper density profiles. Longitudinal gas motions toward OMC-1 may limit the mass supply available for large-scale growth in the outer sub-regions and help maintain the observed range of local exponents. These results link local density scaling to gravitational concentration within a single connected filamentary system.
Comments10 pages, 4 figures. Submitted to ApJ
