AREPO White Dwarf merger simulations resulting in edge-lit detonation and run-away hypervelocity companion

Abstract

We present a series of high-resolution simulations generated with the moving-mesh code AREPO to model the merger of a $1.1{\mathrm{M}}_{\odot }$ carbon-oxygen primary white dwarf with an outer helium layer and a $0.35{\mathrm{M}}_{\odot }$ secondary helium white dwarf. Our simulations lead to detonations that are consistent with the edge-lit scenario, where a helium detonation is ignited at the base of the helium layer of the primary WD, which triggers an off-centre carbon detonation. This produces an asymmetric ejecta pattern and differences in line-of-sight observables (e.g. mean atomic weight). The ejecta that are flung into space are dominated by ${}^{56}\mathrm{Ni}$, ${}^4\mathrm{He}$, ${}^{28}\mathrm{Si}$, and ${}^{32}\mathrm{S}$. Our simulations result in a surviving degenerate companion of mass $0.22-0.25$ ${\mathrm{M}}_{\odot }$ moving at $>1700$ $\mathrm{km}{\mathrm{s}}^{-1}$, consistent with the observational findings of hypervelocity WDs. The secondary's surface layers are enriched by heavy metals, with ${}^{56}\mathrm{Ni}$ making up approximately $0.8\%$ of the remaining mass. We also analyse the sensitivity of the outcome on simulation parameters, including the "inspiral time", which defines a period of accelerated angular momentum loss. We find that the choice of "inspiral time" qualitatively influences the simulation result, including the survival of the secondary. We argue that the shorter inspiral cases result in qualitatively and quantitatively similar outcomes. We also investigate the sensitivity of our results on the primary's chemical profile by comparing simulations using isothermal, constant composition models with the same mass and central composition and characterised by either a bare carbon-oxygen core (no helium) or a carbon-oxygen core enveloped by a thick helium layer.

arXiv commentThe submission has been accepted for publication in the Monthly Notices of the Royal Astronomical Society (MNRAS). 20 pages, 12 figures

References in corpus (53)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• The chemical composition of the Sun
• On the variation of the Initial Mass Function
• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• E pur si muove: Galiliean-invariant cosmological hydrodynamical simulations on a moving mesh
• Evolution of binary stars and the effect of tides on binary populations
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Observational clues to the progenitors of Type-Ia supernovae
• Three-dimensional delayed-detonation models with nucleosynthesis for Type Ia supernovae
• The Arepo public code release
• The single degenerate channel for the progenitors of type Ia supernovae
• Improving the convergence properties of the moving-mesh code AREPO
• Rates and Delay Times of Type Ia Supernovae
• Helium-ignited violent mergers as a unified model for normal and rapidly declining Type Ia Supernovae
• Magnetohydrodynamics on an unstructured moving grid
• Mass Transfer between Double White Dwarfs
• Head-on collisions of white dwarfs in triple systems could explain type Ia supernova
• Low-Metallicity Inhibition of Type Ia Supernovae and Galactic and Cosmic Chemical Evolution
• Three Hypervelocity White Dwarfs in Gaia DR2: Evidence for Dynamically Driven Double-Degenerate Double-Detonation Type Ia Supernovae
• Double-detonation supernovae of sub-Chandrasekhar mass white dwarfs
• Observational Predictions for Sub-Chandrasekhar Mass Explosions: Further Evidence for Multiple Progenitor Systems for Type Ia Supernovae
• The structure and fate of white dwarf merger remnants
• Supernovae Rates: A Cosmic History
• Nuclear fusion in dense matter: Reaction rate and carbon burning
• Delay Times and Rates for Type Ia Supernovae and Thermonuclear Explosions from Double-detonation Sub-Chandrasekhar Mass Models
• The Ignition of Carbon Detonations via Converging Shock Waves in White Dwarfs
• On the brightness distribution of Type Ia supernovae from violent white dwarf mergers
• Stellar GADGET: A smooth particle hydrodynamics code for stellar astrophysics and its application to Type Ia supernovae from white dwarf mergers
• Magnetic fields in isolated and interacting white dwarfs
• Spontaneous Initiation of Detonations in White Dwarf Environments: Determination of Critical Sizes
• Every interacting double white dwarf binary may merge
• The Most Magnetic Stars
• How the merger of two white dwarfs depends on their mass ratio: orbital stability and detonations at contact
• Double detonations of sub-Chandrasekhar mass CO white dwarfs: Can different core and He shell masses explain variations of Type Ia supernovae?
• On the formation of neutron stars via accretion-induced collapse in binaries
• On the fate of the secondary white dwarf in double-degenerate double-detonation Type Ia supernovae
• Non-Local Thermodynamic Equilibrium Radiative Transfer Simulations of Sub-Chandrasekhar-Mass White Dwarf Detonations
• Most Double Degenerate Low Mass White Dwarf Binaries Merge
• Magnetic Field Generation in Stars
• 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
• Double-Detonation Models for Type Ia Supernovae: Trigger of Detonation in Companion White Dwarfs and Signatures of Companions' Stripped-off Materials
• Wait for it: Post-supernova winds driven by delayed radioactive decays
• Nucleosynthesis imprints from different Type Ia Supernova explosion scenarios and implications for galactic chemical evolution
• Type Ia Supernova Sub-classes and Progenitor Origin
• Observational constraints on the origin of the elements. III. Evidence for the dominant role of sub-Chandrasekhar SN Ia in the chemical evolution of Mn and Fe in the Galaxy
• Constraints on the pairing properties of main sequence stars from observations of white dwarfs in binary systems
• WDEC - A code for modeling white dwarf structure and pulsations
• Initiation of the detonation in the gravitationally confined detonation model of Type Ia supernovae
• The circumstellar matter of supernova 2014J and the core-degenerate scenario
• Pre-Explosive Observational Properties of Type Ia Supernovae
• Limits on a population of collisional-triples as progenitors of Type-Ia supernovae

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