Evaluating Systematic Dependencies of Type Ia Supernovae: The Influence of Central Density

TL;DR

This study uses numerical models to analyze how the central density of white dwarf progenitors affects the brightness of Type Ia supernovae, revealing that higher densities lead to dimmer explosions due to less Ni-56 production.

Contribution

It introduces a systematic analysis of progenitor central density effects on supernova brightness using 2D simulations, providing a new brightness-age relation for single-degenerate supernovae.

Findings

Higher central density correlates with less Ni-56 production.

Fe-group material production is independent of central density.

Higher density progenitors produce dimmer supernovae.

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 Ni-56, 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 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 Ni-56 at higher central densities. These results imply progenitors with higher central densities produce dimmer events. We provide details of the post-explosion distribution of Ni-56 in the models, including the lack of a consistent centrally-located deficit of Ni-56, 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.