Competitive roles of turbulence and magnetic field on the formation of unipolar outflows in isolated molecular cloud cores

Abstract

We investigate the impact of turbulence and magnetic field on the formation of unipolar outflows in the gravitational collapse of isolated low-mass cloud cores using three-dimensional non-ideal magnetohydrodynamics simulations. In the models explored in this study, we find that unipolar outflows are formed in cloud cores with the super-Alfvénic turbulence of $M_{\rm{A}}>1$, where $M_{\rm{A}}$ is the Alfvén Mach number of the initial cloud core. In contrast, bipolar outflows are formed in cloud cores with $M_{\rm{A}}\lesssim1$. Our results suggest that the relative strength of the turbulence to the magnetic field in the initial cloud core plays a key role in the formation of unipolar outflows. We also find that no outflow is formed in cloud cores with the strong magnetic field of the dimensionless mass-to-flux ratio $μ=2$. The outflow morphologies can be used as tracers to indirectly estimate the relative strengths of the turbulence and magnetic field of the parent cloud cores.