2023ApJ...945..160L

We present ALMA dust polarization and molecular line observations toward four clumps (I(N), I, IV, and V) in the massive star-forming region NGC 6334. In conjunction with large-scale dust polarization and molecular line data from JCMT, Planck, and NANTEN2, we make a synergistic analysis of relative orientations between magnetic fields (θ_B), column density gradients (θ_NG), local gravity (θ_LG), and velocity gradients (θ_VG) to investigate the multi-scale (from ∼30 to 0.003 pc) physical properties in NGC 6334. We find that the relative orientation between θ_B and θ_NG changes from statistically more perpendicular to parallel as column density (${N}_{{{\rm{H}}}_{2}}$) increases, which is a signature of trans-to-sub-Alfvénic turbulence at complex/cloud scales as revealed by previous numerical studies. Because θ_NG and θ_LG are preferentially aligned within the NGC 6334 cloud, we suggest that the more parallel alignment between θ_B and θ_NG at higher ${N}_{{{\rm{H}}}_{2}}$ is because the magnetic field line is dragged by gravity. At even higher ${N}_{{{\rm{H}}}_{2}}$, the angle between θ_B and θ_NG or θ_LG transits back to having no preferred orientation, or statistically slightly more perpendicular, suggesting that the magnetic field structure is impacted by star formation activities. A statistically more perpendicular alignment is found between θ_B and θ_VG throughout our studied ${N}_{{{\rm{H}}}_{2}}$ range, which indicates a trans-to-sub-Alfvénic state at small scales as well, and this signifies that magnetic field has an important role in the star formation process in NGC 6334. The normalized mass-to-flux ratio derived from the polarization-intensity gradient (KTH) method increases with ${N}_{{{\rm{H}}}_{2}}$, but the KTH method may fail at high ${N}_{{{\rm{H}}}_{2}}$ due to the impact of star formation feedback.