56Ni Production in Double Degenerate White Dwarf Collisions

TL;DR

This study investigates white dwarf collisions as a pathway to type Ia supernovae, analyzing how different collision parameters influence the production of radioactive nickel-56, which affects supernova brightness.

Contribution

It provides detailed simulations of white dwarf collisions, revealing how mass, impact parameter, and mass ratio affect 56Ni yield and supernova observability, highlighting non-linear dependencies.

Findings

56Ni production varies from sub-luminous to super-luminous supernovae.

Small impact parameters increase the likelihood of detonation.

Larger primary masses produce disproportionately more 56Ni.

Abstract

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, {\alpha}-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 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.