Thesis Research

My thesis title is "Recurrent Novae and Type Ia Supernova Progenitors" and it is freely available on the LSU Electronic Theses and Dissertations website. (Some of the chapters have already been published, but others are still in prep. I ask that you wait to use any specific numbers until after they have been published in a refereed journal.) My thesis brings together four projects I worked on as a graduate student and combines them with other new research to take a fresh look at the Type Ia supernova progenitor problem. Although we've empirically calibrated SN Ia lightcurves, turning them into the most useful standard(izable) candles and using them to discover the acceleration of the expansion of our universe, we still don't know exactly where they come from. There must be at least one carbon-oxygen white dwarf, and it must be near the Chandrasekhar mass limit, but the identity of the companion star that donates the material needed to push the WD over the limit, causing the Ia explosion, has been a mystery for decades.

Recurrent novae have been promising progenitor candidates for many years, but our current research shows that they can account for at most ~50% of the observed Ia explosions. Our recent result, published in Nature, shows that a Ia explosion that occurred in the Large Magellanic Cloud ~400 years ago must have had a double-WD progenitor.

At this point, we know that at least one system had a double-WD (double-degenerate) progenitor, but we cannot at this point extend that to all SNe Ia. What is looking to be ever more likely is that there are two types of systems that provide the SNe Ia (the dual-channel hypothesis): half coming from single-degenerate systems (such as RNe) and half from double-degenerate systems.