Accretion induced collapse of white dwarfs in binary systems and their observational properties

Neutron stars can form through core collapse (CC) following a supernova explosion of a massive star, or from a white dwarf that first forms in a binary system and then collapses into a neutron star via accretion induced collapse (AIC). So far, there have been no unambiguous identifications of AIC neutron stars in our Galaxy, although it has been suspected that they may exist among the population of binary millisecond pulsars (BMSPs). We summarise results of new calculations on the expected birth rates of binary systems with AIC neutron stars and discuss the predicted orbital period of systems with He, CO and O-Ne-Mg white dwarfs and main sequence companions. We argue that AIC systems may make an important contribution to the observed population of BMSPs.