Twisted Pseudodisk and Asymmetric Mass Accretion on the Circumstellar Disk

Abstract

We model gas inflow patterns onto circumstellar disks and the evolution of the pseudodisk using three-dimensional resistive MHD simulations. Starting from a prestellar core without turbulence and with a misalignment between the initial magnetic field and rotation axis, the simulations are performed for $\sim10^5$ yr after protostar formation. After disk formation, the magnetic field around the disk becomes significantly distorted due to the disk rotational motion. Consequently, the structure of the pseudodisk also evolves into a complex morphology. As a result, both accretion onto the disk and outflow become asymmetric and anisotropic. Accretion to the disk occurs primarily through narrow-channel flows or streams. The time evolution of the infalling envelope leads to non-steady accretion onto the disk, which in turn causes variability in the mass accretion onto the central protostar. This study demonstrates that complex infalling envelope structures and channelized accretion flows onto the disk naturally arise even without assuming turbulence or external asymmetric inflows.