Modeling of the ALMA HL Tau Polarization by Mixture of Grain Alignment and Self-scattering

Dust polarization at (sub)millimeter wavelengths has been observed for many protoplanetary disks. Theoretically, multiple origins potentially contribute to the polarized emission but it is still uncertain what mechanism dominant in disk millimeter polarization. To quantitatively address origin, we perform radiative transfer calculations of mixture alignment and self-scattering-induced reproduce 3.1 mm HL Tau disk, which shows azimuthal pattern vectors. We find that a grain self-scattering essential properties. Our model can be decomposed combination parallel minor axis alignment-induced major axis, with orders ∼ 0.5% fraction each component. This slightly eases tight constraints on size 70 μm 130 previous studies further modeling needed. In addition, requires effectively prolate grains physics disks mystery.