Abstract
Type Ia supernovae are theorized to originate from the thermonuclear explosion of carbon-oxygen-white dwarfs (C/O WDs), which gives rise to one of the most energetic and luminous optical transients. However, the stellar progenitors of Type Ia supernovae are a subject of active investigation. Theoretical models have predicted the generation of Type Ia supernovae in binary systems - either accreting hydrogen-rich material from another main-sequence or red-giant companion through the single-degenerate channel, or from another degenerate white dwarf trough the double-degenerate channel. Moreover, recent observations of certain ultra-faint events, referred to as Type Iax supernovae, are not readily accommodated by either channel. In particular, stellar evolutionary calculations demonstrate that while sun-like stars will produce carbon-oxygen white dwarfs at the end of the lifespans, more massive intermediate-mass progenitor stars, evolving as late-stage super-AGB stars, will instead produce oxygen-neon (O/Ne) core WDs. Investigations into hydrodynamical explosions of systems harboring O/Ne core WDs have been a subject of interest due to their lesser susceptibility to nuclear combustion, and their possibility of producing lower kinetic energy and less ejected ⁵⁶Ni in comparison to deflagrating C/O WDs. Hence the O/Ne core WDs represent a possible stellar progenitor for subluminous Type Iax-like events, or fainter. Correspondingly, in my thesis, I explore the nature of progenitor of Type Iax supernovae in the context of the double-degenerate channel model of merging white dwarfs. I have carried out fully three-dimensional simulations of the merger of a 1.1 M C/W WD with a 1.2 M O/Ne WD. I demonstrate the result of this merger is a failed detonation, resulting in the ejection of a small amount of mass, and leaving behind a kicked O/Ne WD remnant, enriched by the fallback of the products of nuclear burning. The resulting outburst is a rapidly-fading optical transient with a small amount of radioactive ⁵⁶Ne powering the bolometric light curve. The model produces a very faint and rapidly-fading transient, even fainter than the faintest Type Iax event to date, SN 2008ha.