Observability of Forming Planets and their Circumplanetary Disks III. -- Polarized Scattered Light

Abstract

There are growing amount of very high-resolution polarized scattered light images of circumstellar disks. Nascent giant planets planets are surrounded by their own circumplanetary disks which may scatter and polarize both the planetary and stellar light. Here we investigate whether we could detect circumplanetary disks with the same technique and what can we learn from such detections. Here we created scattered light mock observations at 1.245 microns (J band) for instruments like SPHERE and GPI, for various planetary masses (0.3, 1.0, 5.0, 10.0 $\rm{M_{Jup}}$), disk inclinations (90, 60, 30, 0 degrees) and planet position angles (0, 45, 90 degrees). We found that the detection of a circumplanetary disk at 50AU from the star is significantly favored if the planet is massive ($\geq 5 \rm{M_{Jup}}$) and the system is nearly face-on ($\leq 30^\circ$). In these cases the accretion shock front on the surface of the circumplanetary disks are strong and bright enough to help the visibility of this subdisk. Its detection is hindered by the neighboring circumstellar disk that also provides a strong polarized flux. However, the comparison between the $PI$ and the $Q_\phi$ maps is a viable tool to pinpoint the presence of the circumplanetary disk within the circumstellar disk, as the two disks are behaving differently on those images.