Two-dimensional simulations of disks in close binaries

Simulating outburst cycles in cataclysmic variables

¹ Institute of Astronomy and Astrophysics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
² Faculty of Physics, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany

Received: 24 November 2023
Accepted: 11 July 2024

Abstract

Context. 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.

Aims. We self-consistently simulate complete outburst cycles of normal and superoutbursts in cataclysmic variable systems in two dimensions. We study the effect of different α viscosity parameters, mass transfer rates, and binary mass ratios on the disk luminosities, outburst occurrence rates, and superhumps.

Methods. 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.

Results. 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.