Super-resolution Imaging of ALMA images with Sparse Modeling:
Application to Protoplanetary Disks in the Taurus Star-forming region.

Speaker: Masayuki Yamaguchi (University of Tokyo, *Student talk)


In the recent observations with ALMA, multiple gap structures have been found in giant protoplanetary disks (radius of 50 -100 au), suggesting that the masses of planets that can exist within those gaps are comparable to the mass of Saturn-Jupiter (Andrews. et al. 2018, Zhang et al. 2018). On the other hand, ALMA snapshot surveys show that many disks (~70 % of the abundance) in the low-mass star-forming regions are small disks with a disk radius of less than 30 – 40 au. However, most of them are not spatially resolved by ALMA and the detailed structure of those disks remains unexplored (Ansdell et al. 2016, 2017, 2018, Barenfeld et al. 2016, Cieza et al. 2018, Long et al. 2019). To overcome this limitation of spatial resolution, we have promoted the development of a new super-resolution imaging based on sparse modeling; validation using ALMA observing data has demonstrated that sparse modeling achieves approximately three times higher spatial resolution than conventional methods (Yamaguchi et al. 2020). In line with the success of this validation, new super-resolution imaging software for ALMA (named “PRIISM”) was developed (Nakazato & Ikeda. 2020). Based on our analyzing method so far, we applied the PRIISM to the ALMA continuum data (Band6, 0″.1 resolution) of 34 protoplanetary disks in the Taurus star-forming region, unveiling that a large proportion of giant and small disks have a gap structure in the radius of 10-20 au on the super-resolution domain (Yamaguchi et al. In prep). In this talk, my presentation is organized into three parts: (1) the principle of image reconstruction in radio interferometry, (2) the application to ALMA data with sparse modeling, and (3) the contribution to science (i.e., protoplanetary disks).