Thursday, March 7, 2013

1303.1180 (Doron Kushnir et al.)

The Progenitors of Type Ia Supernova Explosions are Head-On Collisions of White Dwarfs in Triple Systems    [PDF]

Doron Kushnir, Boaz Katz, Subo Dong, Eli Livne, Rodrigo Fernández
We argue that type Ia supernovae (SNe Ia) are the result of head-on collisions of White Dwarfs (WDs) in triple systems. The thermonuclear explosions resulting from the zero-impact-parameter collisions of WDs are calculated from first principles by using 2D hydrodynamical simulations. Collisions of typical WDs with masses 0.5-0.9 M_Sun result in explosions that synthesize Ni56 masses in the range of 0.15-0.8 M_Sun, spanning the wide distribution of yields observed for the majority of SNe Ia. The robustness of the shock ignition process is verified with a detailed study using a one-dimensional toy model and analytic tools. The late-time (~50 days after peak) bolometric light curve is equal to the instantaneous energy deposition and is calculated exactly, by solving the transport of gamma-rays emitted by the decay of Ni56 using a Monte-Carlo code. All collisions are found to have the same late-time light curves, when normalized to the amount of synthesized Ni56. This universal light curve is shown to agree with the majority of the supernovae in the compilation made by M. Stritzinger to an accuracy of better than 30% in the range 40View original:

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