Two-dimensional simulations of disks in close binaries. Simulating outburst cycles in cataclysmic variables

Abstract

Previous simulations of cataclysmic variables studied either the quiescence, or the outburst state in multiple dimensions or they simulated complete outburst cycles in one dimension using simplified models for the gravitational torques. We self-consistently simulate complete outburst cycles of normal and superoutbursts in cataclysmic variable systems in two dimensions. We study the effect of different alpha viscosity parameters, mass transfer rates, and binary mass ratios on the disk luminosities, outburst occurrence rates, and superhumps. We simulate non-isothermal, viscous accretion disks in cataclysmic variable systems using a modified version of the Fargo code with an updated equation of state and a cooling function designed to reproduce s-curve behavior. Our simulations can model complete outburst cycles using the thermal tidal instability model. We find higher superhump amplitudes and stronger gravitational torques than previous studies, resulting in better agreement with observations.