Magnetic Spirals in Accretion Flows Originated from Misaligned Magnetic Field

TL;DR

This study investigates how misaligned magnetic fields influence accretion flows and disk formation in protostellar systems, revealing the roles of magnetic and gravitational torques and the formation of magnetized spiral structures.

Contribution

It provides a detailed analysis of the physics behind magnetic spirals in accretion flows, highlighting the roles of various torques and the impact of ambipolar diffusion.

Findings

Magnetic and gravitational torques significantly influence angular momentum transfer.

Magnetized inflow spirals form aligned with magnetic fields.

Ambipolar diffusion has limited impact on large-scale morphology.

Abstract

Misalignment between rotation and magnetic field has been suggested to be one type of physical mechanisms which can easen the effects of magnetic braking during collapse of cloud cores leading to formation of protostellar disks. However, its essential factors are poorly understood. Therefore, we perform a more detailed analysis of the physics involved. We analyze existing simulation data to measure the system torques, mass accretion rates and Toomre Q parameters. We also examine the presence of shocks in the system. While advective torques are generally the strongest, we find that magnetic and gravitational torques can play substantial roles in how angular momentum is transferred during the disk formation process. Magnetic torques can shape the accretion flows, creating two-armed magnetized inflow spirals aligned with the magnetic field. We find evidence of an accretion shock that is aligned according to the spiral structure of the system. Inclusion of ambipolar diffusion as explored in this work has shown a slight influence in the small scale structures but not in the main morphology. We discuss potential candidate systems where some of these phenomena could be present.