delay time distribution

The term delay time distribution (DTD) is used regarding supernovae and other observable events in the life of stars, for a characterization (e.g., a probability density function) of the likely times between a star formation episode and some particular type of event. The term is commonly used for types of supernovae, perhaps especially core collapse supernovae but also Type Ia supernovae and can be used for other types of events late in the life of a star such as neutron star mergers. Deriving such a distribution from observation and comparing it to those produced by theories is a method of evaluating theories, and a well-established distribution is useful in modelling the history of galaxies and their star formation.