2025MNRAS.541.2216B -
Mon. Not. R. Astron. Soc., 541, 2216-2230 (2025/August-2)
Evidence of .Ia supernova detonations in 3D hydrodynamical simulations of double degenerate mergers.
BURMESTER U.P., FERRARIO L., PAKMOR R. and SEITENZAHL I.R.
Abstract (from CDS):
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 utilize 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.
Abstract Copyright:
© The Author(s) 2025. Published by Oxford University Press on behalf of Royal Astronomical Society.
Journal keyword(s):
accretion, accretion discs - methods: numerical - binaries: general - supernovae: general - white dwarfs - transients: supernovae
Simbad objects:
7
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