Supernovae from direct collisions of white dwarfs and the role of helium shell ignition

Abstract

Models for supernovae (SNe) arising from thermonuclear explosions of white dwarfs (WDs) have been extensively studied over the last few decades, mostly focusing on the single degenerate (accretion of material of a WD) and double degenerate (WD-WD merger) scenarios. In recent years it was suggested that WD-WD direct collisions provide an additional channel for such explosions. Here we extend the studies of such explosions, and explore the role of Helium-shells in affecting the thermonuclear explosions. We study both the impact of low-mass helium ($\sim 0.01$ M${}_{\odot })$ shells, as well as high mass shells ($\ge 0.1$ M${}_{\odot }$). We find that detonation of the massive helium layers precede the detonation of the WD Carbon-Oxygen (CO) bulk during the collision and can change the explosive evolution and outcomes for the cases of high mass He-shells. In particular, the He-shell detonation propagates on the WD surface and inefficiently burns material prior to the CO detonation that later follows in the central parts of the WD. Such evolution leads to larger production of intermediate elements, producing large yields of ${}^{44}\mathrm{Ti}$ and ${}^{48}\mathrm{Cr}$ relative to the pure CO-CO WD collisions. Collisions of WDs with a low-mass He-shell do not give rise to helium detonation, but helium burning does precede the CO bulk detonation. Such collisions produce a high velocity, low-mass of ejected burned material enriched with intermediate elements, with smaller changes to the overall explosion outcomes. The various effects arising from the contribution of low/high mass He layers change the kinematics and the morphological structure of collision-induced SNe and may thereby provide unique observational signatures for such SNe, and play a role in the chemical enrichment of galaxies and the production of intermediate elements and positrons from their longer-term decay.

Final version. Accepted for publication in ApJ

References in corpus (9)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• Faint Thermonuclear Supernovae from AM Canum Venaticorum Binaries
• A survey of the high order multiplicity of nearby solar-type binary stars with Robo-AO
• Unstable Helium Shell Burning on Accreting White Dwarfs
• Fe emission and ionized excess absorption in the luminous quasar 3C109 with XMM-Newton
• A Spatially Resolved Study of the Synchrotron Emission and Titanium in Tycho's Supernova Remnant with NuSTAR
• Tidal capture formation of Low Mass X-Ray Binaries from wide binaries in the field
• Swift/BAT detection of hard X-rays from Tycho's Supernova Remnant: Evidence for Titanium-44

Cited by in corpus (20)

• Type Ia Supernova Explosions in Binary Systems: A Review
• A Unified Mechanism for Unconfined Deflagration-to-Detonation Transition in Terrestrial Chemical Systems and Type Ia Supernovae
• Evidence for sub-Chandrasekhar-mass progenitors of Type Ia supernovae at the faint end of the width-luminosity relation
• The rate of WD-WD head-on collisions in isolated triples is too low to explain standard type Ia supernovae
• Formation and evolution of hybrid He-CO white dwarfs and their properties
• Nucleosynthesis in thermonuclear supernovae
• Neutron star - white dwarf mergers: Early evolution, physical properties, and outcomes
• The detonation of a sub-Chandrasekhar-mass white dwarf at the origin of the low-luminosity Type Ia supernova 1999by
• Stable nickel production in Type Ia supernovae: A smoking gun for the progenitor mass?
• Return of the TEDI: revisiting the Triple Evolution Dynamical Instability channel in triple stars
• A statistical view on stable and unstable Roche lobe overflow of a tertiary star onto the inner binary in triple systems
• The Most Metal-poor Stars in the Inner Bulge
• The Whisper of a Whimper of a Bang: 2400 Days of the Type Ia SN 2011fe Reveals the Decay of ${}^{55}$Fe
• The Late-Time Light Curves of Type Ia Supernovae: Confronting Models with Observations
• Limits on a population of collisional-triples as progenitors of Type-Ia supernovae
• Numerical Stability of Detonations in White Dwarf Simulations
• White dwarf dynamical interactions and fast optical transients
• Merging White Dwarf Binaries Produce Type Ia Supernovae in Elliptical Galaxies
• Thermonuclear explosion criteria for direct and indirect collisions of CO white dwarfs: a study of the impact-parameter threshold for detonation
• Ranking Theoretical Supernovae Explosion Models from Observations of the Intracluster Gas