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No double detonations but core carbon ignitions in high-resolution, grid-based simulations of binary white dwarf mergers

Title: No Double Detonations But Core Carbon Ignitions In High-resolution, Grid-based Simulations Of Binary White Dwarf Mergers.
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Name(s): Fenn, D., author
Plewa, T., author
Gawryszczak, A., author
Type of Resource: text
Genre: Text
Date Issued: 2016-11-01
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: We study the violent phase of the merger of massive binary white dwarf systems. Our aim is to characterize the conditions for explosive burning to occur, and identify a possible explosion mechanism of Type Ia supernovae. The primary components of our model systems are carbon-oxygen (C/O) white dwarfs, while the secondaries are made either of C/O or of pure helium. We account for tidal effects in the initial conditions in a self-consistent way, and consider initially well-separated systems with slow inspiral rates. We study the merger evolution using an adaptive mesh refinement, reactive, Eulerian code in three dimensions, assuming symmetry across the orbital plane. We use a corotating reference frame to minimize the effects of numerical diffusion, and solve for self-gravity using a multigrid approach. We find a novel detonation mechanism in C/O mergers with massive primaries. Here, the detonation occurs in the primary's core and relies on the combined action of tidal heating, accretion heating, and self-heating due to nuclear burning. The exploding structure is compositionally stratified, with a reverse shock formed at the surface of the dense ejecta. The existence of such a shock has not been reported elsewhere. The explosion energy (1.6 x 10(51) erg) and Ni-56 mass (0.86 M-circle dot) are consistent with an SN Ia at the bright end of the luminosity distribution, with an approximated decline rate of Delta m(15)(B) approximate to 0.99. Our study does not support double-detonation scenarios in the case of a system with a 0.6 M-circle dot helium secondary and a 0.9 M-circle dot primary. Although the accreted helium detonates, it fails to ignite carbon at the base of the boundary layer or in the primary's core.
Identifier: FSU_libsubv1_wos_000384676000015 (IID), 10.1093/mnras/stw1831 (DOI)
Keywords: adaptive mesh refinement, binaries: close, failed deflagration model, helium detonations, hydrodynamics, ia supernovae, nuclear reactions, nucleosynthesis, abundances, off-center detonation, shock waves, smoothed particle hydrodynamics, stellar astrophysics, supernovae: general, supernova sn 2011fe, surface detonations, thermonuclear supernovae, white dwarfs
Publication Note: The publisher’s version of record is available at https://doi.org/10.1093/mnras/stw1831
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000384676000015
Owner Institution: FSU
Is Part Of: Monthly Notices of the Royal Astronomical Society.
0035-8711
Issue: iss. 3, vol. 462

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Fenn, D., Plewa, T., & Gawryszczak, A. (2016). No Double Detonations But Core Carbon Ignitions In High-resolution, Grid-based Simulations Of Binary White Dwarf Mergers. Monthly Notices Of The Royal Astronomical Society. Retrieved from http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000384676000015