Giant planets and brown dwarfs on wide orbits: a code comparison project

Abstract

Gas clumps formed within massive gravitationally unstable circumstellar discs are potential seeds of gas giant planets, brown dwarfs and companion stars. Simulations show that competition between three processes -- migration, gas accretion and tidal disruption -- establishes what grows from a given seed. Here we investigate the robustness of numerical modelling of clump migration and accretion with the codes PHANTOM, GADGET, SPHINX, SEREN, GIZMO-MFM, SPHNG and FARGO. The test problem comprises a clump embedded in a massive disc at an initial separation of 120 AU. There is a general qualitative agreement between the codes, but the quantitative agreement in the planet migration rate ranges from $\sim 10$% to $\sim 50$%, depending on the numerical setup. We find that the artificial viscosity treatment and the sink particle prescription may account for much of the differences between the codes. In order to understand the wider implications of our work, we also attempt to reproduce the planet evolution tracks from our hydrodynamical simulations with prescriptions from three previous population synthesis studies. We find that the disagreement amongst the population synthesis models is far greater than that between our hydrodynamical simulations. The results of our code comparison project are therefore encouraging in that uncertainties in the given problem are probably dominated by the physics not yet included in the codes rather than by how hydrodynamics is modelled in them.

submitted to MNRAS. This is version 2 of the paper after considering referees comments and changes

References in corpus (18)

• Smoothed Particle Hydrodynamics and Magnetohydrodynamics
• The Burst Mode of Protostellar Accretion
• On the diversity and statistical properties of protostellar discs
• Inviscid SPH
• A Triple Protostar System Formed via Fragmentation of a Gravitationally Unstable Disk
• Galactic Centre stellar winds and Sgr A* accretion
• Type I planetary migration in a self-gravitating disk
• Can giant planets form by gravitational fragmentation of discs?
• Treating gravity in thin disk simulations
• The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs at wide orbits: II- Survey description, results and performances
• Saturated torque formula for planetary migration in viscous disks with thermal diffusion: recipe for protoplanet population synthesis
• Observational evidence for two distinct giant planet populations
• Towards a population synthesis model of self-gravitating disc fragmentation and tidal downsizing II: The effect of fragment-fragment interactions
• On the gap-opening criterion of migrating planets in protoplanetary disks
• Convergence of the critical cooling rate for protoplanetary disk fragmentation achieved; the key role of numerical dissipation of angular momentum
• Dawes Review. The tidal downsizing hypothesis of planet formation
• Identifying and Analysing Protostellar Disc Fragments in Smoothed Particle Hydrodynamics Simulations
• The effect of radiative feedback on disc fragmentation