Nonlinear outcome of gravitational instability in an irradiated protoplanetary disc

Abstract

Using local three dimensional radiation hydrodynamics simulations, the nonlinear outcome of gravitational instability in an irradiated protoplanetary disc is investigated in a parameter space of the surface density $\Sigma$ and the radius $r$. Starting from laminar flow, axisymmetric self-gravitating density waves grow first. Their self-gravitating degree becomes larger when $\Sigma$ is larger or the cooling time is shorter at larger radii. The density waves eventually collapse owing to non-axisymmetric instability, which results in either fragmentation or gravito-turbulence after a transient phase. The boundaries between the two are found at $r\sim 75$ AU as well as at the $\Sigma$ that corresponds to the initial Toomre's parameter of $\sim 0.2$. The former boundary corresponds to the radius where the cooling time becomes short, approximating unity. Even when gravito-turbulence is established around the boundary radius, such a short cooling time inevitably makes the fluctuation of $\Sigma$ large enough to trigger fragmentation. On the other hand, when $\Sigma$ is beyond the latter boundary (i.e. the initial Toomre's parameter is less than $\sim 0.2$), the initial laminar flow is so unstable against self-gravity that it evolves into fragmentation regardless of the radius or, equivalently, the cooling time. Runaway collapse follows fragmentation when the mass concentration at the centre of a bound object is high enough that the temperature exceeds the H${}_2$ dissociation temperature.

accepted for publication in MNRAS

References in corpus (7)

• Spiral Density Waves in a Young Protoplanetary Disk
• Characterising the Gravitational Instability in Cooling Accretion Discs
• The Mass Budget of Planet Forming Discs: Isolating the Epoch of Planetesimal Formation
• Effects of radiation transfer on the structure of self-gravitating disks, their fragmentation and evolution of the fragments
• Gravito-Turbulent Disks in 3D: Turbulent Velocities vs. Depth
• Magnetic Turbulence and Thermodynamics in the Inner Region of Protoplanetary Discs
• The Effect of Protoplanetary Disk Cooling Times on the Formation of Gas Giant Planets by Gravitational Instability

Cited by in corpus (6)

• 3D Radiation Hydrodynamic Simulations of Gravitational Instability in AGN Accretion Disks: Effects of Radiation Pressure
• Spiral structures in gravito-turbulent gaseous disks
• Optab: Public code for generating gas opacity tables for radiation hydrodynamics simulations
• Gravito-turbulence in local disk simulations with an adaptive moving mesh
• Standing solitary waves as transitions to spiral structures in gravitationally unstable accretion disks
• Nonlinear analysis of gravitational instability in a 3D gaseous disc