Inward-then-outward migration of Jupiter and Saturn and its implications for Uranus and Neptune

Jupiter and Saturn formed in the gaseous Solar Nebula and were subject to gas-driven migration. The "Grand Tack" model of Walsh et al. (2011) proposes that Jupiter and Saturn underwent a two phase, inwardthen- outward migration that sculpted the inner Solar System. We use hydrodynamical simulations to investigate how Jupiter and Saturn's orbital history depends on both the giant planets' accretion history and the disk properties (viscosity, density, radiative properties). We show that a two phase migration of Jupiter and Saturn is a robust outcome that is independent of the growth history of these planets, and fits coherently within the framework of an evolving Solar Nebula. We then test the impact on the growth of Uranus and Neptune. For some system parameters the ice giants undergo a rapid burst of accretion during the short outward migration phase of Jupiter and Saturn. We also find that co-orbital configurations are common between the ice giants (or sometimes between an ice giant and a gas giant).