Phase Transition of Newborn Neutron Stars as a Link of Supernova/Gamma-Ray Burst Connection

We here present a natural explanation of the puzzling connection between supernova and gamma-ray burst. An asymmetric supernova explosion produces a mildly relativistic jet and leaves a preferred baryon-free funnel for the fireball formed few days later by the conversion of the newborn neutron star to a strange star, or/and from the differentially rotating strange star. The fireball can be accelerated to ultra-relativistic velocity (Γ0 > 100) due to the very low baryon contamination of the strange star and subsequently produce the γ-ray burst. Most of the conversion energy will finally turn into the kinetic energy of the supernova ejecta, leading to a very luminous supernova similar to SN1998bw. We also show that the late rise in the radio light curve of GRB980425/SN1998bw can be attributed to the energy input from the resultant strange star. subject headings: gamma-ray: bursts — supernova: general — stars: neutron — elementary particles