Oral Presentation

Millimeter-wave polarization of protoplanetary disks: alignment or scattering?

Author(s): Akimasa Kataoka (National Astronomical Observatory of Japan)

Presenter: Akimasa Kataoka (National Astronomical Observatory of Japan)

The interpretation of polarization of protoplanetary disks at millimeter wavelengths has been dramatically evolving. We propose that the self-scattering of thermal dust emission can produce millimeter-wave polarization in protoplanetary disks. We show that the self-scattering produces polarization with a fraction of ~2.5 %. Furthermore, by performing multi-wave polarization observations, we can constrain the grain size because the polarization is the most efficient when the grain size is comparable to the wavelengths. We also report two ALMA polarization observations of protoplanetary disks toward HD142527 and HL Tau. We detect the polarized emissions in both cases. In the case of HD 142527, we confirm that the self-scattering is working by morphological discussions. In the case of HL Tau, the polarization pattern at 3.1 mm is completely different from that at 1.3 mm. We interpret that the strong wavelength dependence is due to the self-scattering. By modeling the polarized emission, we constrain the grain size to be 70 micron.