Presentation #328.03 in the session Dust.
For a proper analysis of the Cosmic Microwave Background (CMB) radiation data from sub-mm missions, it is crucial to be able to confidently establish the emission polarization of the Galaxy’s dust foreground.
This foreground dust also polarizes optical starlight. We use this fact to obtain optical linear polarization measurements of a few thousand stars scattered across the field of the BICEP2 CMB experiment to a polarimetric S/N better than 5. We were able to map the polarization level and magnetic field structure. This is a first step towards estimating the foreground polarization at sub-mm wavelengths.
Our data show two main polarization components, one of them relatively ordered and another of a random character. We combine our data with those from GAIA EDR3 and attempt at a preliminary 3-D model for the Galactic dust distribution and magnetic field structure.