Time Evolution of 3D Disk Formation with Misaligned Magnetic Field and Rotation Axes

Abstract

Distinguishing diagnostic observational signatures produced by MHD models is essential in understanding the physics for the formation of protostellar disks in the Atacama Large Millimeter/submillimeter Array era. Developing suitable tools along with time evolution will facilitate better identification of diagnostic features. With the ray-tracing-based radiative transfer code P erspective we explore the time evolution of MHD models carried out in Li et al.—most of which have 90° misalignment between the rotational axis and the magnetic field. Four visible object types can be characterized, origins of which are dependent on the initial conditions. Our results show complex spiraling density, velocity, and polarization structures. The systems are under constant change, but many of those distinctive features are present already early on, and they grow more visible in time, but most could not be identified from the data without examining their change in time. The results suggest that spiraling pseudo-disk structures could function as an effective observation signature of the formation process, and we witness accretion in the disk with eccentric orbits that appear as spiral-like perturbation from simple circular Keplerian orbits. Magnetically aligned polarization appears purely azimuthal in the disk, and the magnetic field can lead to precession of the disk.