SOFIA/HAWC+ Far-Infrared Polarimetric Large Area CMZ Exploration Survey. V. The Magnetic Field Strength and Morphology in the Sagittarius C Complex

TL;DR

This study uses far-infrared polarimetry data from SOFIA/HAWC+ to analyze the magnetic field strength and structure in the Sagittarius C complex of the Galactic Center, revealing variations linked to turbulence, star formation, and cloud interactions.

Contribution

It provides the first detailed magnetic field strength and morphology measurements in Sgr C using HAWC+ polarimetry, applying a modified DCF method to individual clouds.

Findings

Magnetic field strength varies from ~30 μG to ~300 μG across regions.

Polarization fraction increases toward cloud peripheries.

Magnetic fields are influenced by star formation outflows and HII region dynamics.

Abstract

We present an analysis of the magnetic field strength and morphology in the Sagittarius C complex (Sgr C; G359.43-0.09) in the Milky Way Galaxy's Central Molecular Zone (CMZ), using the 214 $\mu$m polarimetry data acquired with the High-resolution Airborne Wide-band Camera (HAWC+) instrument aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). We conduct a modified Davis-Chandrasekhar-Fermi (DCF) analysis of individual clouds and find that the sky-plane magnetic field strength varies from highly turbulent regions having inferred strengths of $\sim30~\mu{\rm G}$ to regions of relatively uniform field orientation having strengths of $\sim 300~\mu{\rm G}$. Several hundred magnetic field pseudovectors in the Sgr C region were measured to trace the projected magnetic field orientation within cold molecular clouds, and as is the trend throughout the CMZ, they show a higher polarization fraction toward the periphery of the clouds. The magnetic field orientations suggest that outflows from active star-forming regions, such as the G359.43-0.10 extended green object (EGO) and the protostellar source FIR-4 (G359.43+0.02), cause high turbulence in their vicinity. The magnetic field direction is found to be tangential to the surface of the Sgr C HII region, which displays spatial correspondence with two [CII] emission cavities reported in the HII region, signifying a compression front between the HII region and the surrounding dense clouds. Several other features in the vicinity of Sgr C, especially numerous non-thermal radio filaments (NTFs) and a diffuse source of X-ray emission to the immediate southwest of the HII region, are discussed with regard to the magnetic field measurements.