Mass transfer dynamics in double degenerate binary systems

Abstract

We present a numerical study of the mass transfer dynamics prior to the gravitational wave-driven merger of a double white dwarf system. Recently, there has been some discussion about the dynamics of these last stages, different methods seemed to provide qualitatively different results. While earlier SPH simulations indicated a very quick disruption of the binary on roughly the orbital time scale, more recent grid-based calculations find long-lived mass transfer for many orbital periods. Here we demonstrate how sensitive the dynamics of this last stage is to the exact initial conditions. We show that, after a careful preparation of the initial conditions, the reportedly short-lived systems undergo mass transfer for many dozens of orbits. The reported numbers of orbits are resolution-biased and therefore represent only lower limits to what is realized in nature. Nevertheless, the study shows convincingly the convergence of different methods to very similar results.

5 pages, 3 figures, for associated movie files, see http://pandora.jacobs-university.de/~mdan/WD_coalescences.htm, to appear in Journal of Physics Conference Proceedings for the 16th European White Dwarf Workshop

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• Violent mergers of nearly equal-mass white dwarf as progenitors of subluminous Type Ia supernovae
• Astrophysical Smooth Particle Hydrodynamics
• The ESO supernovae type Ia progenitor survey (SPY)
• The merger of binary white dwarf-neutron stars: Simulations in full general relativity
• Head-on collisions of binary white dwarf--neutron stars: Simulations in full general relativity
• Twin Binaries: Studies of Stability, Mass Transfer, and Coalescence
• Constructing Synchronously Rotating Double White Dwarf Binaries
• Mass Transfer in Binary Stars using SPH. I. Numerical Method
• Angular Momentum Exchange in White Dwarf Binaries Accreting Through Direct Impact
• A Numerical Method for Studying Super-Eddington Mass Transfer in Double White Dwarf Binaries
• Halted-Pendulum Relaxation: Application to White Dwarf Binary Initial Data