Work

Examining Turbulence in Galactic Molecular Clouds. II. Turbulence Cascade Beyond the Scale of Giant Molecular Clouds

Year: 2026

Type: article

Abstract: We use 12 CO ( J = 1–0) data from the MWISP survey to investigate turbulence in a ∼kiloparsec-scale segment of the Local Arm. By slicing the position–position–velocity cube into narrow layers that follow the Galactic-rotation trend in the L – V diagram, we find that the structure functions (SFs) and spatial power spectra (SPS) of the 12 CO ( J = 1–0) line velocity and intensity exhibit consistent scaling behaviors across all layers, demonstrating that the molecular gas forms a single, coherent turbulent field with energy cascading from ∼200 pc down to parsec scales. The SPS power-law slopes of both the intensity and velocity fields approach the values expected from turbulence models. Cloud-to-cloud velocity SFs based on the molecular clouds located in the region follow the same extended self-similarity scaling (ESS) as the pixel-based statistics, indicating that intercloud motions are part of the same large-scale turbulent cascade. Together, these results provide direct observational evidence that molecular clouds are not dynamically isolated entities but are embedded within a larger-scale turbulent flow that links galactic dynamics to star formation on cloud scales.

Source: The Astrophysical Journal

DOI: 10.3847/1538-4357/aea610