Global Simulations of Accretion Disks I: Convergence and Comparisons with Local Models

Understand

Grid-based magnetohydrodynamic (MHD) simulations have proven invaluable for the study of astrophysical accretion disks.

• However, the fact that angular momentum transport in disks is mediated by MHD turbulence (with structure down to very small scales) raises the concern that the properties of the modeled accretion disks are affected by the finite numerical resolution of the simulation.
• By implementing an orbital advection algorithm into the Athena code in cylindrical geometry, we have performed a set of global (but unstratified) Newtonian disk simulations extending up to resolutions previously unattained.
• We study the convergence of these models as a function of spatial resolution and initial magnetic field geometry.