Ejecta Mass Ratios in Kepler’s SNR & Fitting Highly Complex Global SNR Spectra

The exact origins of many Type Ia supernovae—progenitor scenarios and explosive mechanisms—remain uncertain. In this talk, I present analysis of the global spectrum of Kepler’s SNR to compare observed ejecta mass ratios to the predictions of simulations. However, fits to the complex spectral emission from the entirety of Kepler’s SNR have large residuals that negatively impact maximum likelihood fitting statistics. Here, I present an approach for treating uncertainties by performing multiple fittings to the data and using the resultant spread in locally minimized parameters to estimate true best-fit parameter uncertainties. Additionally, we characterize the systematic uncertainties from the unknown filling factors of each fit plasma component. Our resultant mass ratio estimates strongly favor an 90% attenuation of the ¹²C+¹⁶O reaction rate and are potentially consistent with range of both near- and sub-Chandrasekhar mass progenitors with various properties. More modeling—multi-dimensional, using this attenuated reaction rate and covering a wider range of progenitor and explosion property combinations—is required to put stricter constraints on Kepler’s progenitor.