Abstract:
We present a study exploring a systematic effect on the brightness of Type Ia supernovae using numerical models that
assume the single-degenerate paradigm. Our investigation varied the central density of the progenitor white dwarf
at flame ignition, and considered its impact on the explosion yield, particularly the production and distribution
of radioactive 56Ni, which powers the light curve. We performed a suite of two-dimensional simulations with
randomized initial conditions, allowing us to characterize the statistical trends that we present. The simulations
indicate that the production of Fe-group material is statistically independent of progenitor central density, but the
mass of stable Fe-group isotopes is tightly correlated with central density, with a decrease in the production of
56Ni at higher central densities. These results imply that progenitors with higher central densities produce dimmer
events. We provide details of the post-explosion distribution of 56Ni in the models, including the lack of a consistent
centrally located deficit of 56Ni, which may be compared to observed remnants. By performing a self-consistent
extrapolation of our model yields and considering the main-sequence lifetime of the progenitor star and the elapsed
time between the formation of the white dwarf and the onset of accretion, we develop a brightness–age relation that
improves our prediction of the expected trend for single degenerates and we compare this relation with observations.
