George C. Jordan IV, Hagai B. Perets, Robert T. Fisher, Daniel R. van Rossum
Type Ia supernovae (SNe Ia) are thought to originate from the thermonuclear explosions of carbon-oxygen (C-O) white dwarfs (WDs). The gravitationally-confined detonation (GCD) model is a well-explored explosion model where unstable thermonuclear burning initiates in an accreting, Chandrasekhar-mass WD and forms an advancing flame. Rising, burning material breaks out of the WD surface, engulfs the WD, and leads to a gradient-induced detonation in the collision region, which subsequently unbinds the WD. We show that when the flame consumes enough fuel, the conditions for detonation are not met, and the WD does not detonate. We show through 2D and 3D simulations, such failed-detonation SNe expel a few 0.1 Msolar of burned and partially-burned material, but do not unbind the WD. A fraction of the material falls back onto the WD, polluting the remnant WD with intermediate-mass and iron-group elements, that likely segregate to the core forming an iron-core C-O WD. The remaining material is asymmetrically ejected at velocities comparable to the escape velocity from the WD, and in response, the WD is kicked to velocities of a few hundred km/s. Such kicks may unbind the binary and eject a runaway/hyper-velocity WD. Although the energy and ejected mass of the failed-detonation SN are a fraction of typical thermonuclear SNe, they are likely to appear as sub-luminous low-velocity SNe Ia. Such failed-GCDs might therefore explain or are related to the observed branch of peculiar SNe Ia, such as the family of low-velocity sub-luminous SNe (SN 2002cx/SN 2008ha-like SNe).
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http://arxiv.org/abs/1208.5069
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