A Local One-Zone Model of MHD Turbulence in Dwarf Nova Disks

Abstract

The evolution of the magnetorotational instability (MRI) during the transition from outburst to quiescence in a dwarf nova disk is investigated using three-dimensional MHD simulations. The shearing box approximation is adopted for the analysis, so that the efficiency of angular momentum transport is studied in a small local patch of the disk: this is usually referred as to a one-zone model. To take account of the low ionization fraction of the disk, the induction equation includes both ohmic dissipation and the Hall effect. We induce a transition from outburst to quiescence by an instantaneous decrease of the temperature. The evolution of the MRI during the transition is found to be very sensitive to the temperature of the quiescent disk. As long as the temperature is higher than a critical value of about 2000 K, MHD turbulence and angular momentum transport is sustained by the MRI. However, MHD turbulence dies away within an orbital time if the temperature falls below this critical value. In this case, the stress drops off by more than 2 orders of magnitude, and is dominated by the Reynolds stress associated with the remnant motions from the outburst. The critical temperature depends slightly on the distance from the central star and the local density of the disk.

arXiv comment20 pages, 2 tables, 6 figures, accepted for publication in ApJ

References in corpus (12)

• Linear Analysis of the Hall Effect in Protostellar Disks
• The Balbus-Hawley instability in weakly ionised discs
• The Effect of Resistivity on the Nonlinear Stage of the Magnetorotational Instability in Accretion Disks
• Magnetohydrodynamical Non-radiative Accretion Flows in Two-Dimensions
• The Effect of the Hall Term on the Nonlinear Evolution of the Magnetorotational Instability: II. Saturation Level and Critical Magnetic Reynolds Number
• The Effect of the Hall Term on the Nonlinear Evolution of the Magnetorotational Instability: I. Local Axisymmetric Simulations
• A Magnetohydrodynamic Nonradiative Accretion Flow in Three Dimensions
• On the origin of episodic accretion in Dwarf Novae
• Saturation and Thermalization of the Magnetorotational Instability: Recurrent Channel Flows and Reconnections
• Nonlinear Evolution of the Magnetorotational Instability in Ion-Neutral Disks
• Viscosity Mechanisms in Accretion Disks
• Hot white dwarfs and the UV delay in dwarf novae

Cited by in corpus (8)

• On the Linear Stability of Weakly-Ionized, Magnetized Planar Shear Flows
• Magnetorotational instability in protoplanetary discs
• Convection Causes Enhanced Magnetic Turbulence in Accretion Disks in Outburst
• Vortices in Thin, Compressible, Unmagnetized Disks
• Magnetorotational instability in stratified, weakly ionised accretion discs
• Magnetic Turbulence and Thermodynamics in the Inner Region of Protoplanetary Discs
• Self-similar structure of resistive ADAFs with outflow and large-scale magnetic field
• FUSE Observations of the Dwarf Nova SW UMa During Quiescence