A Magnetic Ribbon Model for Star-Forming Filaments

TL;DR

This paper introduces a magnetic ribbon model for star-forming filaments in molecular clouds, emphasizing the roles of turbulence, magnetic fields, and ambipolar diffusion in filament formation, and matches observed filament width relations.

Contribution

The paper presents a novel magnetic ribbon model derived from simulations, explaining filament widths and their relation to column density beyond traditional Jeans length assumptions.

Findings

The model predicts a relatively flat relation between apparent width and column density.

Synthetic observations from the model align with actual filament width observations.

Magnetic effects and turbulence are key to filament structure, not just gravity.

Abstract

We develop a magnetic ribbon model for molecular cloud filaments. These result from turbulent compression in a molecular cloud in which the background magnetic field sets a preferred direction. We argue that this is a natural model for filaments and is based on the interplay between turbulence, strong magnetic fields, and gravitationally-driven ambipolar diffusion, rather than pure gravity and thermal pressure. An analytic model for the formation of magnetic ribbons that is based on numerical simulations is used to derive a lateral width of a magnetic ribbon. This differs from the thickness along the magnetic field direction, which is essentially the Jeans scale. We use our model to calculate a synthetic observed relation between apparent width in projection versus observed column density. The relationship is relatively flat, similar to observations, and unlike the simple expectation based on a Jeans length argument.