Global accretion disk simulations of magneto-rotational instability

Abstract

We perform global three-dimensional simulations of accretion disks integrating the compressible, non-viscous, but diffusive MHD equations. The disk is supposed to be isothermal. We make use of the ZEUS-3D code integrating the MHD equations and added magnetic diffusivity. We measure the efficiency of the angular-momentum transport. Various model simulations delivered transport parameters of alpha_SS=0.01 to 0.05 which are consistent with several local numerical investigations. Two of the models reach a highly turbulent state at which alpha_SS is of the order of 0.1. After a certain stage of saturating of the turbulence, Reynolds stress is found to be negative (inward transport) in many of the models, whereas Maxwell stresses dominate and deliver a positive (outward) total transport. Several of the models yield strongly fluctuating Reynolds stresses, while Maxwell stresses are smooth and always transport outwards. Dynamo action is found in the accretion disk simulations. A positive dynamo-alpha is indicated in the northern hemisphere of the most prominent run, coming along with negative kinetic and current helicities (all having the opposite sign on the southern side). The dipolar structure of the magnetic field is maintained throughout the simulations, although indication for a decay of antisymmetry is found. The simulations covered relatively thick disks, and results of thin-disk dynamo models showing quadrupolar fields may not be compatible with the results presented here.

13 pages, LaTeX, submitted to A&A

Cited by in corpus (28)

• Zonal Flows and Long-Lived Axisymmetric Pressure Bumps in Magnetorotational Turbulence
• Dust diffusion in protoplanetary discs by magnetorotational turbulence
• Trapping Solids at the Inner Edge of the Dead Zone: 3-D Global MHD Simulations
• Turbulence and Steady Flows in 3D Global Stratified MHD Simulations of Accretion Disks
• The variability of accretion onto Schwarzschild black holes from turbulent magnetized discs
• Polarized NIR and X-ray Flares from SgrA*
• Turbulence and its parameterization in accretion discs
• Characterization of GX 339-4 outburst of 2010-11: analysis by xspec using two component advective flow model
• Large Scale Azimuthal Structures Of Turbulence In Accretion Disks - Dynamo triggered variability of accretion
• Modelling MHD accretion-ejection - episodic ejections of jets triggered by a mean-field disk dynamo
• Papaloizou-Pringle instability suppression by the magnetorotational instability in relativistic accretion discs
• Is Compton cooling sufficient to explain evolution of observed quasi-periodic oscillations in Outburst sources?
• Axisymmetric Magnetorotational Instability in Viscous Accretion Disks
• Global simulations of magnetorotational turbulence I: convergence and the quasi-steady state
• Dynamo generated magnetic configurations in accretion discs and the nature of quasi-periodic oscillations in accreting binary systems
• Characterising the Dynamo in a Radiatively Inefficient Accretion Flow
• Segregation of a Keplerian disc and sub-Keplerian halo from a Transonic flow around a Black Hole by Viscosity and Cooling processes
• Differential rotation decay in the radiative envelopes of CP stars
• General Relativistic Numerical Simulation of sub-Keplerian Transonic Accretion Flows onto Black Holes: Schwarzschild Spacetime
• Multifluid simulations of the Magnetorotational Instability in protostellar disks
• Search for non-helical disc dynamos in simulations
• 3D global simulations of RIAFs: convergence, effects of azimuthal extent and dynamo
• An evolving hot spot orbiting around Sgr A*
• Compressibility and local instabilities of differentially rotating magnetized gas
• Global simulations of magnetorotational turbulence II: turbulent energetics
• Magnetic shear-driven instability and turbulent mixing in magnetized protostellar disks
• Thermomagnetic instability in hot discs
• Current-driven instabilities in weakly ionized disks