Smoothed Particle Hydrodynamics simulations of merging white dwarfs

Abstract

We present the results of three-dimensional Smoothed Particle Hydrodynamics (SPH) calculations of the process of coalescence of white dwarfs. We follow in detail the initial phase of the merging for several masses of the primary and the secondary of the binary system. Special attention has been paid to the issue of whether or not thermonuclear runaway occurs during the process of merging. We find that although relatively high temperatures are attained during the most violent phase of the merging process, the thermonuclear flash is rapidly quenched. The total mass lost by the system is also relatively small (of the order of 0.5% at most) except for the most massive primaries for which it is still small (-2.2%). Consequently, a heavy accretion disk around the primary is formed. We also discuss the subsequent evolution of the resulting system and the possible astrophysical scenarios of interest.