Bipolar Outflow Momentum Depending on Misalignment of Outflow Axes and Magnetic Field Orientations

ABSTRACT :
Bipolar outflows are most energetic phenomena in protostellar systems and are thought to be launched magneto-centrifugally. However, it is little known whether and how bipolar outflow strengths depend on magnetic fields observationally. We present a relationship between bipolar outflow momenta and magnetic field orientations with respect to the outflow directions using ALMA and JCMT data of protostellar systems located in the Orion molecular cloud. We calculated the outflow momenta for 48 out of 56 protostellar systems using ALMA CO 3-2 data and inferred the magnetic field orientations using ALMA continuum polarimetric data in Band 7. Despite difficulties in determining the directions of magnetic fields due to distortion and self-scattering on small scales and the small number of targets, we found that outflow momenta are greater when the offset between outflow axes and magnetic fields is intermediate, compared to when they are perpendicular or parallel. In addition to the relatively small scales (~1000 AU), we obtained large scale (~10000 AU) magnetic field orientations using JCMT POL2-SCUBA data and found the consistent result.