Properties of Close Double White Dwarfs

Double white dwarfs are today the leading candidates to be the hosts of Type Ia supernovae which are amongst the optically brightest stellar explosions and of importance to cosmology. The aim of this project is to exploit the Gaia survey for its selectivity in identifying such systems, and in particular systems in which both components are visible allowing the determination of mass ratios. These are crucial for unravelling the evolutionary history of these systems and thus for calibrating the theoretical models that underly predictions of Type Ia supernova evolution. The research involves identification of suitable targets within the Gaia survey and spectroscopic follow up. It will also involve high-speed photometric measurement of known close double white dwarf pairs in order to measure period changes to measure gravitational wave emission and the effect of tides, both of which are important in how the white dwarfs eventually merge. The same data will be used to measure the fundamental parameters of the two stars which are needed to test binary population synthesis models.