Probing Magnetic Fields in Protoplanetary Disk Atmospheres through Polarized Near-IR Light Scattered by Aligned Grains

Magnetic fields play essential roles in protoplanetary disks. the disk atmosphere are of particular interest, as they connected to wind-launching mechanism. In this work, we study polarization light scattered off magnetically aligned grains atmosphere, focusing on deviation orientation from canonical azimuthal direction, which may be detectable near-IR polarimetry with instruments such VLT/SPHERE. We show a simple model that can even oriented along radial (rather than azimuthal) especially highly inclined disks toroidally dominated magnetic fields. This reversal is caused by anisotropy polarizibility and thus telltale sign grains. mostly $\mu$m-sized or smaller at $\tau=1$ surface if contain superparamagnetic inclusions. For comparison observations, generate synthetic maps ratios $U_\phi/I$ $Q_\phi/I$, used infer existence (magnetically) through negative $Q_\phi$ (polarization reversal) and/or significant level $U_\phi/I$. two features observed existing data, an asymmetric distribution $U_\phi$ respect minor axis spatial predominantly positive negative, incompatible scattering spherical axisymmetric disk. They provide indirect evidences for non-spherical