Magnetically Driven Obliquity in Circumplanetary Disks and Twisted Bipolar-jet Formation

RESUMO

Circumplanetary disks (CPDs) regulate gas accretion onto forming giant planets and provide the environment in which their satellites may form. We use high-resolution, global three-dimensional simulations to investigate the early formation, orientation, and outflows of a CPD around a Jupiter-mass planet embedded in a turbulent magnetized protoplanetary disk. Within a locally isothermal, ideal-MHD framework, we evolve disks threaded by net vertical magnetic fields, corresponding to initial plasma parameters $875\leq\beta\leq3500$, until magnetorotational-instability-driven turbulence is established before inserting the planet. We also perform a hydrodynamic control simulation. In the most strongly magnetized model, with $\beta=875$, the CPD forms already highly inclined and reaches a maximum tilt of approximately $87^\circ$. By contrast, the hydrodynamic CPD and the MHD models with $\beta\gtrsim1000$ remain nearly coplanar. A control simulation in which the planet is inserted before global MRI turbulence develops also remains coplanar, despite producing local turbulence and bipolar outflows. The large tilt is therefore associated with the pre-existing global turbulent state and its evolved velocity and toroidal magnetic-field structure, although our current diagnostics do not distinguish between a direct magnetic torque and the accretion of misaligned angular momentum. All MHD models launch bipolar outflows; in the highly tilted case, these develop a curved, helical morphology that persists until the end of our short-term simulations. These results identify pre-existing global magnetized turbulence as a viable route to generating strongly inclined CPDs and twisted planetary outflows.