The impact of turbulence and magnetic field orientation on star forming filaments

TL;DR

This study uses simulations to explore how turbulence and magnetic field orientation affect the evolution, stability, and fragmentation of star-forming filaments, revealing conditions that influence their width and collapse modes.

Contribution

It provides new insights into the effects of magnetic field orientation and turbulence on filament stability and fragmentation, aligning simulation results with recent observations.

Findings

Magnetic fields parallel to the filament stabilize against radial collapse.

Filament widths vary with magnetic field orientation and turbulence.

Fragmentation modes depend on mass, magnetic field, and perturbations.

Abstract

We present simulations of collapsing filaments studying the impact of turbulence and magnetic field morphologies on their evolution and star formation properties. We vary the mass per unit length of the filaments as well as the orientation of the magnetic field with respect to the major axis. We find that the filaments, which have no or a perpendicular magnetic field, typically reveal a smaller width than the universal width of 0.1 pc proposed by e.g. Arzoumanian et al. 2011. We show that this also holds in the presence of supersonic turbulence and that accretion driven turbulence is too weak to stabilize the filaments along their radial direction. On the other hand, we find that a magnetic field that is parallel to the major axis can stabilize the filament against radial collapse resulting in widths of 0.1 pc. Furthermore, depending on the filament mass and magnetic field configuration, gravitational collapse and fragmentation in filaments occurs either in an edge-on way, uniformly distributed across the entire length, or in a mixed way. In the presence of initially moderate density perturbations, a centralized collapse towards a common gravitational centre occurs. Our simulations can thus reproduce different modes of fragmentation observed recently in star forming filaments. Moreover, we find that turbulent motions influence the distance between individual fragments along the filament, which does not always match the results of a Jeans analysis.