2010ApJ...711L..66B

The recognition that the metallicity of Type Ia supernova (SNIa) progenitors might bias their use for cosmological applications has led to an increasing interest in its role in shaping SNIa light curves. We explore the sensitivity of the synthesized mass of ⁵⁶Ni, M(⁵⁶Ni), to the progenitor metallicity starting from pre-main-sequence models with masses M₀= 2-7 M_☉ and metallicities Z = 10^–5-0.10. The interplay between convective mixing and carbon burning during the simmering phase eventually raises the neutron excess, η, and leads to a smaller ⁵⁶Ni yield, but does not change substantially the dependence of M(⁵⁶Ni) on Z. Uncertain attributes of the progenitor white dwarf, like the central density, have a minor effect on M(⁵⁶Ni). Our main results are: (1) a sizeable amount of ⁵⁶Ni is synthesized during incomplete Si-burning, which leads to a stronger dependence of M(⁵⁶Ni) on Z than obtained by assuming that ⁵⁶Ni is produced in material that burns fully to nuclear statistical equilibrium; (2) in one-dimensional delayed detonation simulations a composition dependence of the deflagration-to-detonation transition (DDT) density gives a nonlinear relationship between M(⁵⁶Ni) and Z and predicts a luminosity larger than previously thought at low metallicities (however, the progenitor metallicity alone cannot explain the whole observational scatter of SNIa luminosities); and (3) an accurate measurement of the slope of the Hubble residuals versus metallicity for a large enough data set of SNIa might give clues to the physics of DDT in thermonuclear explosions.