NIR polarimetry as a probe of the large-scale structure of the Galactic Magnetic Field

Pavel Michael, pavelmi@bu.edu, Boston University, United States

Abstract
Near-infrared (1.6 micron) starlight polarimetry was used to test predictions of the large-scale symmetry properties of the Galactic magnetic field and to measure the Galactic magnetic pitch angle. Polarimetry was obtained with the Mimir instrument on the 1.8m Perkins Telescope outside of Flagstaff, AZ USA along a line of constant Galactic longitude (L=150 deg) for a range of Galactic latitudes (-75 < b <10 deg). Comparison with all-sky predictions of starlight polarimetry allow significant rejection of disk anti-symmetric Galactic magnetic field geometries and favored disk symmetric geometries. The Galactic magnetic field pitch angle was also constrained to be p=-6(2) degrees towards this direction.