Modelling the diversity of spectra and light curves of thermonuclear supernovae

Type Ia supernovae are bright astrophysical transients that are understood to be caused by thermonuclear explosions of white dwarf stars in binaries. White dwarfs are remnants left behind when low-mass stars reach the end of their lives, and so these explosions are a key aspect of stellar evolution. The extreme conditions in thermonuclear explosions means that nucleosynthesis occurs and produces heavy elements up to, and including, the iron-peak. This makes thermonuclear supernovae critical for understanding the build-up of heavy elements in galaxies. Furthermore, they are sufficiently bright to see at extremely large distances and most of them fade at a rate that follows a well-established pattern that can be used to calibrate their true luminosities. This makes Type Ia supernovae powerful cosmological probes that have been widely used to study the expansion rate of the Universe and test models of dark energy. Thus, thermonuclear supernovae are important to a broad range of research in astronomy and remain a topic of active international research. However, we still lack a clear understanding of their nature: how do white dwarf systems evolve to the point at which thermonuclear ignition occurs, and what is the mechanism that causes the explosion to disrupt the star? Our project aims to address such questions by using theory to identify the observable signatures of different explosion scenarios. Specifically, we use numerical radiative transfer calculations to predict time series of spectra for models of thermonuclear supernovae. These can be compared to observations to test the underlying explosion theory and distinguish between models. We also make our predictions publicly available so they can be used by the community to help interpret new data or compare with alternative models.
It is well established that thermonuclear supernovae are a diverse population. Aside from the “normal” Type Ia events, there are multiple distinct sub-classes that differ in their...