Περίληψη :
Linear polarization occurs when starlight passes through elongated dust grains aligned by interstellar magnetic fields. The observed polarization can originate from various dust structures along the line of sight (LOS). By combining polarization measurements with stellar distances, we can study the Galactic magnetic field (GMF) in the plane of the sky between the observer and the star and separate the contributions of clouds with different GMF properties. We used optical and near-infrared (NIR) polarization data from three regions in the Galactic plane to perform a polarization decomposition across the Galactic arms. We applied Bayesian Inference of Starlight Polarization in one dimension and Gaussian Mixture Model methods to decompose the polarization in these three regions. Optical and NIR observations complemented each other, consistently identifying nearby (d ≲ 143 pc), intermediate (0.47 kpc < d < 1.2 kpc), and distant (1.5 kpc < d < 2.5 kpc) polarizing clouds. These findings are consistent with previous observations of dust structures in the Local Bubble wall, the Local arm, and the Sagittarius arm. Both polarization decomposition methods largely agreed and provided complementary results. Polarization tomography revealed significant LOS variations in the plane-of-sky magnetic field orientation in two of the three regions. The relative alignment between magnetic fields traced by starlight polarization and Planck’s polarized thermal dust emission at 353 GHz reaffirmed these variations.
