Princeton University SFIR: Star Formation/ISM Rendezvous

While recent observations of young protostellar disks have revealed much about their structure, the formation process from molecular cloud cores and subsequent evolution remains relatively poorly understood, with the role of the magnetic field in regulating the angular momentum budget of the system via magnetic braking and outflows being a central issue. In this talk, the first non-ideal magnetohydrodynamics (MHD) simulations of the formation of protostellar disks with the moving-mesh code AREPO are presented. This includes both a large parameter study of isolated cores (with several chemical models and initial geometries) as well as zoom-in simulations from the interstellar medium to protostars, with a spatial range spanning more than 10 orders of magnitude. Extraction of angular momentum is generally substantially reduced via the inclusion of  non-ideal MHD effects, although the Hall effect is seen to have a more complex impact and can actually enhance magnetic braking, in line with previous results. The structure of the resulting disks, some of which are rotationally supported (enabled by non-ideal MHD) and outflows is presented. Non-ideal MHD effects remain crucial in the disk formation process even when fully self-consistent turbulent initial conditions are used, and their importance is therefore not limited to idealized collapse scenarios.