Unveiling the origins of white-dwarf explosions

The explosive deaths of white dwarfs are essential in heavy element nucleosynthesis, galaxy feedback, and for understanding the evolution of binary systems.

Type Ia supernovae (SNe Ia) are famous for their key role as cosmological-distance indicators and in the discovery of the accelerating Universe.

Recent high-cadence surveys, and theoretical advances, have hinted that SNe Ia may not be the dominant way in which white dwarfs explode, with the potential existence of large populations of faint and rapidly evolving white-dwarf explosions.

These unexplored classes of exotic transients may come from white dwarfs being torn apart by intermediate-mass black holes, mergers with neutron stars, or collisions in triple systems, but the mapping between explosions and observed transients is undetermined.

This project aims at providing the first complete census of the multiple ways that white dwarfs explode by mapping their observations to their explosion physics and constraining their diversity.

This sample will be crucial for defining optimal samples of SNe Ia for cosmology, as well as determining the rates and contributions of white-dwarf explosions to the origin of the elements.

We will achieve this by i) obtaining the largest ever, rapidly discovered and spectroscopically confirmed sample, of white-dwarf transients with detailed follow-up observations, ii) the application of machine-learning techniques (e.g., neural-network emulators) for rapid comparison to sophisticated explosion models, and iii) the determination of the rates and diversity of their explosions in different galaxy environments.

The confirmation and exploration of the multiple explosion channels for producing normal SNe Ia and exotic white-dwarf transients will have major implications for their nucleosynthetic yields, their use in cosmology, as well as predicting rates of double white dwarfs that will be detected in huge numbers in the Milky Way by the gravitational-wave detector, LISA.