Fraction of Type Ia supernovae from double white dwarf progenitors

Determine the fraction of Type Ia supernovae that originate from double white dwarf (double-degenerate) progenitor systems, using constraints implied by the population of hypervelocity white dwarf remnants identified with Gaia.

Background

Gaia has enabled the discovery of hypervelocity white dwarfs that are plausibly remnants ejected from thermonuclear supernovae in close white dwarf binaries. These objects provide direct evidence that at least some Type Ia supernovae arise from double-degenerate progenitors.

Quantifying the proportion of Type Ia events that follow this channel remains an outstanding problem, requiring synthesis of Gaia discoveries, supernova demographics, and models of binary evolution and supernova mechanisms.