Delivery of Dust Particles from Protoplanetary Disks onto Circumplanetary Disks of Giant Planets

Abstract

Principal regular satellites of gas giants are thought to be formed by the accumulation of solid materials in circumplanetary disks (CPDs). While there has been significant progress in the study of satellite formation in CPDs, details of the supply of satellite building blocks to CPDs remain unclear. We performed orbital integration of solid particles in the protoplanetary disk (PPD) approaching a planet, considering the gas drag force using the results of three-dimensional hydrodynamical simulations of a local region around the planet. We investigated planetary-mass dependence of the capture positions and capture rates of dust particles accreting onto the CPD. We also examined the degree of dust retention in accreting gas onto the CPD, which is important for determining the ratio of dust-to-gas inflow rates, a key parameter in satellite formation. We found that the degree of dust retention increases with increasing planetary mass for a given dust scale height in the PPD. In the case of a small planet ($M_{\rm p}=0.2M_{\rm Jup}$), most particles with insufficient initial altitudes in the PPD are isolated from the gas in the accreting region. On the other hand, in the case of a massive planet ($M_{\rm p}=1M_{\rm Jup}$), dust particles can be coupled to the vertically accreting gas, even when the dust scale height is about $10-30$\% of the gas scale height. The results of this study can be used for models of dust delivery and satellite formation in the CPDs of gas giants of various masses, including exoplanets.