Beyond Larson’s Law: Unveiling the Universal Structure of Molecular Clouds using Dendrogram Analysis

Abstract

We present observations of the emission of C18O(1–0) and 13CO(1–0) rotational lines in the southern region of the Infrared Dark Cloud G14.225–0.506. Using the dendrograms analysis, we investigate whether the substructures within the cloud obey the first Larson Law: σ ∝ R0.5. Identifying 1061 and 2564 structures for C18O and 13CO respectively, we observe a well-defined correlation between velocity dispersion and size. The obtained power law indices are β = 0.71 and β = 0.65, far from the expected value of 0.5. The smallest structures present a weak relation between the magnitudes, with a lower β power law index. Comparing the results with other works from the literature covering a wide range of spatial scales we conclude that the first Larson Law seems to break at 0.01 - 0.1 pc scales