Ambipolar diffusion and far-infrared polarization from the galactic circumnuclear disk

We describe an implicit prediction of the accretion disk models constructed by Wardle & Konigl for the circumnuclear disk (CND) of gas and dust near the Galactic center: supersonic ambipolar diffusion, an essential dynamical ingredient of the Wardle-Konigl disks, will cause the alignment of dust grains because of a process described by Roberge, Hanany, & Messinger. We calculate synthetic maps of the polarized thermal emission which would be caused by ambipolar alignment in the preferred Wardle-Konigl model. Our maps are in reasonable agreement with 100 mu m polarimetry of the CND if we assume that the grains have shapes similar to those of grains in nearby molecular clouds and that the CND contains a disordered magnetic field in energy equipartition with its ordered field.