Possible evolutionary transition from rapidly rotating neutron stars to strange stars due to spin-down

We present a scenario for the formation of strange stars due to spin-down of rapidly rotating neutron stars left after supernova explosions. In this scenario the rapid rotation plays a crucial role. We assume that the total baryon mass is conserved but that both total energy and angular momentum are lost due to emission of gravitational waves and/or magnetic braking. Under this assumption, we calculate the transition from rapidly rotating neutron stars to slowly rotating strange stars. As a result, we find that a large amount of energy, ∼ 10⁵³, ergs is released. The liberated energy might become a new energy source for the delayed explosion of a supernova. Furthermore, our scenario suggests that supernovas associated with gamma-ray bursts are feasible sources of observable gravitational waves.