High-resolution Smoothed Particle Hydrodynamics simulations of the merger of binary white dwarfs

TL;DR

This paper presents high-resolution Smoothed Particle Hydrodynamics simulations of binary white dwarf mergers, exploring detailed physics, various compositions, and potential observational signatures like gravitational waves and X-ray flares.

Contribution

It introduces an advanced SPH simulation approach with detailed physics and extensive particle resolution to study white dwarf mergers across different masses and compositions.

Findings

Detailed merger dynamics and final configurations

Potential gravitational wave signatures identified

Predicted fallback X-ray flares as observational signatures

Abstract

We present the results of a set of high-resolution simulations of the merging process of two white dwarfs. In order to do so, we use an up-to-date Smoothed Particle Hydrodynamics code which incorporates very detailed input physics and an improved treatment of the artificial viscosity. Our simulations have been done using a large number of particles (4x10^5) and cover the full range of masses and chemical compositions of the coalescing white dwarfs. We also compare the time evolution of the system during the first phases of the coalescence with that obtained using a simplified treatment of mass transfer, we discuss in detail the characteristics of the final configuration, we assess the possible observational signatures of the merger, like the associated gravitational waveforms and the fallback X-ray flares, and we study the long-term evolution of the coalescence.