Estimation of the magnetic field strength from ALMA dust polarization in the protocluster G327.29

TL;DR

This study uses high-resolution ALMA dust polarization data to analyze magnetic field strength and morphology in the high-mass star-forming region G327.29, revealing the magnetic field's significant role over turbulence in core dynamics.

Contribution

First high-resolution measurement of magnetic field strength and morphology in G327.29 using ALMA dust polarization, providing insights into magnetic influence on star formation.

Findings

Magnetic field strength in dense cores is around 1.4 to 2.0 mG.

Magnetic energy dominates over turbulence in core dynamics.

Regions may be gravitationally bound or unbound depending on parameters.

Abstract

Magnetic fields and turbulence may play a crucial role in the evolution of molecular clouds and ultimately in the formation of dense cores and stars. Despite being studied in many molecular clouds, the exact role of magnetic fields and turbulence in star formation is still poorly understood. Here, we report the high resolution plane of sky magnetic field (B_pos) morphology toward the high mass star forming region G327.29, obtained with the 12-meter of the Atacama Large Millimeter/sub-millimeter Array (ALMA) telescope. From our analysis, we obtain a complex B_pos morphology where the magnetic field orientation is uniformly distributed across the entire range from -90 to +90 deg. The observed area is composed of one filament and one dense central clump, which harbor multiple dense cores. The total magnetic field strengths (B_tot) in these regions are 1.4 \pm 0.7 mG and 2.0 \pm 0.8 mG at a number density (n) of 6.8 \pm 1.5 x 10^5 and 1.1 \pm 0.3 x 10^6 cm^-3 , derived from the angular dispersion function (ADF) method. The virial parameters ({\alpha} vir )in these regions are 7.7 \pm 7.1 and 0.7 \pm 0.6, suggesting that the regions may be gravitationally bound or unbound after accounting for the errors. Moreover, the ratio of turbulent to magnetic energy (~ 0.25) indicates that the magnetic field is dynamically more important than turbulence. The relative influence of turbulence and magnetic fields on core dynamics appears to depend on how the B_tot scales with gas density (\r{ho}) in the densest regions. In summary, this work presents a comprehensive analysis of the relative roles of magnetic fields, turbulence, and gravity in regulating high-mass star formation in G327.29, enabled by high-resolution ALMA observations.