The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333

TL;DR

This study uses high-resolution polarization observations to analyze the complex magnetic field structures in the filamentary network of NGC 1333, revealing scale-dependent magnetic alignments and modeling their orientations.

Contribution

It provides the first detailed polarization mapping of individual filaments in NGC 1333 at 0.02 pc resolution, and introduces a simple model explaining the observed magnetic field orientations.

Findings

Magnetic field structure varies significantly below 1 pc scale.

Filaments are generally aligned perpendicular to the magnetic field.

Projection effects can account for the apparent complexity of the magnetic field.

Abstract

We present new observations of the active star-formation region NGC 1333 in the Perseus molecular cloud complex from the James Clerk Maxwell Telescope B-Fields In Star-forming Region Observations (BISTRO) survey with the POL-2 instrument. The BISTRO data cover the entire NGC 1333 complex (~1.5 pc x 2 pc) at 0.02 pc resolution and spatially resolve the polarized emission from individual filamentary structures for the first time. The inferred magnetic field structure is complex as a whole, with each individual filament aligned at different position angles relative to the local field orientation. We combine the BISTRO data with low- and high- resolution data derived from Planck and interferometers to study the multiscale magnetic field structure in this region. The magnetic field morphology drastically changes below a scale of ~1 pc and remains continuous from the scales of filaments (~0.1 pc) to that of protostellar envelopes (~0.005 pc or ~1000 au). Finally, we construct simple models in which we assume that the magnetic field is always perpendicular to the long axis of the filaments. We demonstrate that the observed variation of the relative orientation between the filament axes and the magnetic field angles are well reproduced by this model, taking into account the projection effects of the magnetic field and filaments relative to the plane of the sky. These projection effects may explain the apparent complexity of the magnetic field structure observed at the resolution of BISTRO data toward the filament network.