2010ApJ...724..111R

We present a comprehensive study of white dwarf collisions as an avenue for creating type Ia supernovae. Using a smooth particle hydrodynamics code with a 13-isotope, α-chain nuclear network, we examine the resulting ⁵⁶Ni yield as a function of total mass, mass ratio, and impact parameter. We show that several combinations of white dwarf masses and impact parameters are able to produce sufficient quantities of ⁵⁶Ni to be observable at cosmological distances. We find that the ⁵⁶Ni production in double-degenerate white dwarf collisions ranges from sub-luminous to the super-luminous, depending on the parameters of the collision. For all mass pairs, collisions with small impact parameters have the highest likelihood of detonating, but ⁵⁶Ni production is insensitive to this parameter in high-mass combinations, which significantly increases their likelihood of detection. We also find that the ⁵⁶Ni dependence on total mass and mass ratio is not linear, with larger-mass primaries producing disproportionately more ⁵⁶Ni than their lower-mass secondary counterparts, and symmetric pairs of masses producing more ⁵⁶Ni than asymmetric pairs.