Evidence of .Ia Supernova Detonations in 3D Hydrodynamical Simulations of Double Degenerate Mergers

Abstract

We report detailed 3D simulations of 1.1 ${\mathrm{M}}_{\odot }$ Oxygen-Neon (ONe) white dwarfs (WDs) merging with a 0.35 ${\mathrm{M}}_{\odot }$ helium WD, conducted with the moving-mesh hydrodynamic code AREPO. The simulations utilise self-consistent chemical profiles for the primary WD which were generated by a stellar evolution code incorporating the effects of semi-degenerate carbon burning. We find that a helium detonation is ignited at the base of the helium layer, starting a thermonuclear runaway which encircles the WD and ejects material as a sub-luminous supernovae. Our canonical simulation, (C-120), ejects 0.103 ${\mathrm{M}}_{\odot }$ of primarily ${}^4\mathrm{He}$, ${}^{28}\mathrm{Si}$, and ${}^{32}\mathrm{S}$, after which the primary begins accreting again from the surviving secondary. Our results depend qualitatively on the "inspiral time" simulation parameter, which describes the length of a period of accelerated angular momentum loss. For example, the binary does not survive when inspiral time is too long. We compare the results using our self-consistent chemical profiles to a constant-composition WD structure and find the same explosion pattern when the inspiral time is short. However, we are able to obtain a typical Type Ia supernova (SN Ia) which destroys the primary by using the constant-composition structure and long inspiral. The shock-convergence in this simulation follows the "x-scissor mechanism" described by Gronow et al. in 2020, and causes a secondary detonation due to higher temperatures and higher number density of ${}^{12}\mathrm{C}$ at the convergence site. These results highlight the potential for unrealistic outcomes when conducting simulations that incorporate unrealistically large enhancements in angular momentum losses and (or) non-realistic chemical structures for the primary WD.

15 pages, 9 figures (excluding appendix). Accepted for publication in MNRAS

References in corpus (15)

• Array Programming with NumPy
• A bright millisecond radio burst of extragalactic origin
• Faint Thermonuclear Supernovae from AM Canum Venaticorum Binaries
• Unstable Helium Shell Burning on Accreting White Dwarfs
• Type Ia Supernova Explosions in Binary Systems: A Review
• An unusual white dwarf star may be a surviving remnant of a subluminous Type Ia supernova
• Remnants and ejecta of thermonuclear electron-capture supernovae: Constraining oxygen-neon deflagrations in high-density white dwarfs
• On the fate of the secondary white dwarf in double-degenerate double-detonation Type Ia supernovae
• Thermonuclear explosion of a massive hybrid HeCO white-dwarf triggered by a He-detonation on a companion
• Constructing stable 3D hydrodynamical models of giant stars
• Initiation of the detonation in the gravitationally confined detonation model of Type Ia supernovae
• The fastest stars in the Galaxy
• The non-explosive stellar merging origin of the ultra-massive carbon-rich white dwarfs
• AREPO White Dwarf merger simulations resulting in edge-lit detonation and run-away hypervelocity companion
• Do not forget the electrons: Extending moderately-sized nuclear networks for multidimensional hydrodynamic codes