Type Ia supernovae (SNe Ia) are the thermonuclear explosions of carbon-oxygen white dwarfs (WDs) in binary stellar systems. After many decades of research, the nature of their progenitors is still unclear. There are two main proposed channels: the single-degenerate scenario, where the WD companion is a non-degenerate star (e.g. a main-sequence star, a sub-giant, a red giant or a helium star), and the double-degenerate scenario, where the WD companion is another WD. Some observational probes, such as the neutron excess in the supernova ejecta and the amount and shape of the circumstellar material left behind in the post-explosion supernova remnant (SNR), are sensitive to the properties of the progenitor before, during and after the thermonuclear runaway. Here, we compare the predictions from models of pre-explosion single-degenerate scenarios, explosive nucleosynthesis, and expanding SNRs with real X-ray spectra of SNRs in order to elucidate the properties of their progenitors. We find that a) there is observational evidence for high neutronization in several Type Ia SNRs, b) this neutron-rich content in the supernova ejecta cannot be explained by current chemical evolution models, as it is in tension with the metallicity distribution functions of the Milky Way and the Large Magellanic Cloud, pointing to a different source for the neutron excess, and c) simple one-dimensional hydrodynamical models with uniform ambient media for expanding SNRs are able to reproduce the bulk properties (Fe Kα centroid energy and luminosity, radius and expansion age) of most known Ia SNRs, with a few exceptions.
|Commitee:||Hillier, John, Wood-Vasey, Michael, Boudreau, Joseph, Walker, Matthew|
|School:||University of Pittsburgh|
|Department:||Dietrich School Arts and Sciences|
|School Location:||United States -- Pennsylvania|
|Source:||DAI-B 81/2(E), Dissertation Abstracts International|
|Subjects:||Physics, Astronomy, Astrophysics|
|Keywords:||Atomic data–nuclear reactions, Nucleosynthesis, Abundance, Hydrodynamics, ISM: supernova remnants, Supernovae: general, White dwarfs, X-rays: ISM|
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