Magnetic Fields in Massive Star-Forming Regions (MagMaR) II. Tomography
  Through Dust and Molecular Line Polarization in NGC 6334I(N)
  Here, we report ALMA detections of polarized emission from dust, CS($J=5
\rightarrow 4$), and C$^{33}$S($J=5 \rightarrow 4$) toward the high-mass
star-forming region NGC6334I(N). A clear ``hourglass'' magnetic field
morphology was inferred from the polarized dust emission which is also directly
seen from the polarized CS emission across velocity, where the polarization
appears to be parallel to the field. By considering previous findings, the
field retains a pinched shape which can be traced to clump length-scales from
the envelope scales traced by ALMA, suggesting that the field is dynamically
important across multiple length-scales in this region. The CS total intensity
emission is found to be optically thick ($\tau_{\mathrm{CS}} = 32 \pm 12$)
while the C$^{33}$S emission appears to be optically thin
($\tau_{\mathrm{C^{33}S}} = 0.1 \pm 0.01$). This suggests that sources of
anisotropy other than large velocity gradients, i.e. anisotropies in the
radiation field are required to explain the polarized emission from CS seen by
ALMA. By using four variants of the Davis-Chandrasekhar-Fermi technique and the
angle dispersion function methods (ADF), we obtain an average of estimates for
the magnetic field strength onto the plane of the sky of $\left<
\mathrm{B}_{\mathrm{pos}} \right> = 16$ mG from the dust and $\left<
\mathrm{B}_{\mathrm{pos}} \right> \sim 2$ mG from the CS emission, where each
emission traces different molecular hydrogen number densities. This effectively
enables a tomographic view of the magnetic field within a single ALMA
observation.
