Lecturer: Dan Maoz
Abstract:
Supernovae are Nature's almost-exclusive way of producing the elements from oxygen to iron. Roughly half of the world's iron was formed in so-called Type Ia supernovae (SNe Ia), the thermonuclear explosions of some white dwarf stars. SNe Ia have gained fame as distance indicators that first revealed the dark-energy-driven accelerating universal expansion. However, the precise identity of the exploding systems in SNe Ia, and their explosion mechanism, are major unsolved puzzles. Valuable clues are provided by the delay-time distribution (DTD): the spread of times between the formation of a stellar population and the explosion of some of its members as SNe Ia. I will show how recent attempts to measure the DTD, combined with other evidence, suggests that SNe Ia result from double white-dwarf systems that lose orbital energy to gravitational waves, merge, and explode. In parallel, I will show ongoing work to take the census of the Milky Way's double-white-dwarf systems, before they merge. The observed DTD permits attempting a reconstruction of the history of element creation in our Galaxy and in the Universe as a whole.