Characterizing gravito-turbulence in 3D: turbulent properties and stability against fragmentation

Abstract

We have investigated the properties of gravito-turbulent discs in 3D using high-resolution shearing-box simulations. For large enough domain sizes, $L_y\gtrsim 60H$, the disc settles down into a quasi-steady state, showing no long term trends in properties or variation with box size. For smaller boxes, we find that the azimuthal wavelength of the dominant spiral modes are limited to the domain size. This is associated with a bursty behaviour that differs from the quasi-steady dynamics at larger sizes. We point out that a similar transition may be expected in global simulations at the point where the range of azimuthal wavelengths is limited by the finite disc size. This condition (i.e. when $60H\sim 2\pi R$, i.e. $H/R\sim 0.1$) correctly predicts the transition to bursty behaviour previously found in global simulations for disc-to-star mass ratios in excess of 0.25. We recover a transition in the dynamics from two- to three-dimensional behaviour, characterized by a turbulence that becomes more isotropic on small scales. This turbulence likely plays an important role in the evolution of dust in self-gravitating discs, potentially dominating the collision velocity for particles with Stokes number $<1$. Finally, we consider the stability of gravito-turbulence against fragmentation, finding that discs which cool faster than a few dynamical times fragment immediately, supporting previous results. We also find hints of stochastic fragmentation at marginally longer cooling times, in which a fragment forms from a quasi-equilibrium state. However, this makes little practical difference to region where planet formation via gravitational instability may occur.

14 pages, 10 figures. Accepted for publication in MNRAS

References in corpus (16)

• Athena: A New Code for Astrophysical MHD
• The Statistics of Supersonic Isothermal Turbulence
• Closed-form expressions for particle relative velocities induced by turbulence
• The properties of brown dwarfs and low-mass hydrogen-burning stars formed by disc fragmentation
• Characterising the Gravitational Instability in Cooling Accretion Discs
• The Thermal Regulation of Gravitational Instabilities in Protoplanetary Disks III. Simulations with Radiative Cooling and Realistic Opacities
• Properties of gravitoturbulent accretion disks
• Planetesimal formation via fragmentation in self-gravitating protoplanetary discs
• Convergence of the critical cooling rate for protoplanetary disk fragmentation achieved; the key role of numerical dissipation of angular momentum
• Dust Transport in MRI Turbulent Disks: Ideal and Non-ideal MHD with Ambipolar Diffusion
• The response of self-graviting protostellar discs to slow reduction in cooling timescale: the fragmentation boundary revisited
• The fragmentation criteria in local vertically stratified self-gravitating disk simulations
• Gravito-Turbulent Disks in 3D: Turbulent Velocities vs. Depth
• Gravito-turbulence and the excitation of small-scale parametric instability in astrophysical discs
• Planetesimal formation in self-gravitating discs: the effects of particle self-gravity and back-reaction
• Vortices in self-gravitating gaseous discs

Cited by in corpus (20)

• Global simulations of self-gravitating magnetized protoplanetary disks
• 3D Radiation Hydrodynamic Simulations of Gravitational Instability in AGN Accretion Disks: Effects of Radiation Pressure
• Spiral structures in gravito-turbulent gaseous disks
• Chaotic Gas Accretion by Black Holes Embedded in AGN Discs as Cause of Low-spin Signatures in Gravitational Wave Events
• Direct Formation of Planetary Embryos in Self-Gravitating Disks
• Primordial Obliquities of Brown Dwarfs and Super-Jupiters from Fragmenting Gravito-Turbulent Discs
• Particle Dynamics in 3D Self-gravitating Disks II: Strong Gas Accretion and Thin Dust Disks
• Particle Dynamics in 3D Self-gravitating Disks I: Spirals
• Testing Disk Identification Methods Through Numerical Simulations of Protostellar Evolution
• Formation of pebbles in (gravito-)viscous protoplanetary disks with various turbulent strengths
• An Extension of the Athena++ Framework for Fully Conservative Self-Gravitating Hydrodynamics
• Regulation of star formation by large scale gravito-turbulence
• Self-gravitating planetary envelopes and the core-nucleated instability
• Gravito-turbulence in local disk simulations with an adaptive moving mesh
• Gravito-turbulence and dynamo in poorly ionised protostellar discs. I. Zero-net-flux case
• Turbulence and its connection to episodic accretion in binary YSOs
• Resolving numerical star formation: A cautionary tale
• Dust growth and planet formation by disc fragmentation
• Gravitoturbulent dynamo in global simulations of gaseous disks
• Gravitational instability in planet-forming discs