What role of gravity, turbulence and magnetic fields in high-mass star formation clouds?

Abstract

To explore the potential role of gravity, turbulence and magnetic fields in high-mass star formation in molecular clouds, this study revisits the velocity dispersion--size ($\sigma$--$L$) and density--size ($\rho$--$L$) scalings and the associated turbulent energy spectrum using an extensive data sample. The sample includes various hierarchical density structures in high-mass star formation clouds, across scales of 0.01 to 100 pc. We observe $\sigma \propto L^{0.26}$ and $\rho \propto L^{-1.54}$ scalings, converging toward a virial equilibrium state. A nearly flat virial parameter--mass ($\alpha_{\rm vir}-M$) distribution is seen across all density scales, with $\alpha_{\rm vir}$ values centered around unity, suggesting a global equilibrium maintained by the interplay between gravity and turbulence across multiple scales. Our turbulent energy spectrum ($E(k)$) analysis, based on the $\sigma$--$L$ and $\rho$--$L$ scalings, yields a characteristic $E(k) \propto k^{-1.52}$. These findings indicate the potential significance of gravity, turbulence, and possibly magnetic fields all in regulating dynamics of molecular clouds and high-mass star formation therein.