Relative Alignments Between Magnetic Fields, Velocity Gradients, and Dust Emission Gradients in NGC 1333

TL;DR

This study investigates the relative orientations of magnetic fields, dust emission, and velocity gradients in NGC 1333, revealing mostly parallel alignments with dust emission and complex interactions influenced by physical processes like MHD waves.

Contribution

It provides one of the first detailed analyses of magnetic field and gradient alignments at core scales in a star-forming region, using the Project Rayleigh Statistic.

Findings

Global parallel alignment between magnetic fields and dust emission gradients.

No significant global alignment between magnetic fields and velocity gradients.

Correlation of magnetic field alignments with dust temperature and their anticorrelation with column density and velocity dispersion.

Abstract

Magnetic fields play an important role in shaping and regulating star formation in molecular clouds. Here, we present one of the first studies examining the relative orientations between magnetic ($B$) fields and the dust emission, gas column density, and velocity centroid gradients on the 0.02 pc (core) scales, using the BISTRO and VLA+GBT observations of the NGC 1333 star-forming clump. We quantified these relative orientations using the Project Rayleigh Statistic (PRS) and found preferential global parallel alignment between the $B$ field and dust emission gradients, consistent with large-scale studies with Planck. No preferential global alignments, however, are found between the $B$ field and velocity gradients. Local PRS calculated for subregions defined by either dust emission or velocity coherence further revealed that the $B$ field does not preferentially align with dust emission gradients in most emission-defined subregions, except in the warmest ones. The velocity-coherent structures, on the other hand, also showed no preferred $B$ field alignments with velocity gradients, except for one potentially bubble-compressed region. Interestingly, the velocity gradient magnitude in NGC 1333 ubiquitously features prominent ripple-like structures that are indicative of magnetohydrodynamic (MHD) waves. Finally, we found $B$ field alignments with the emission gradients to correlate with dust temperature and anticorrelate with column density, velocity dispersion, and velocity gradient magnitude. The latter two anticorrelations suggest that alignments between gas structures and $B$ fields can be perturbed by physical processes that elevate velocity dispersion and velocity gradients, such as infall, accretions, and MHD waves.