A possible model for the supernova/gamma-ray burst connection

Conversion from neutron stars to strange stars as a possible mechanism of c osmological gamma-ray bursts (GRB s) has been discussed in previous works, although the existence of strange stars is still an open question. On the b asis of this mechanism, we here outline an explanation of the connection be tween supernovae (SNe) and GRBs, which has got increasing evidence recently . An asymmetric but normal SN explosion leaves a massive (greater than or e qual to 1.8M(circle dot)) and rapidly rotating neutron star, which then con verts to a strange star few days later, due to its rapid spin down. The acc ompanied fireball, which can be accelerated to ultra-relativistic velocity (To similar to 100) due to the very low baryon contamination of the strange star, flows out along the direction of the high-velocity SN jet and subseq uently produces a GRB and the following low energy afterglows by interactin g with the surrounding stellar wind. We will also expect a very luminous su pernova like SN1998bw, if a large fraction of the conversion energy finally turns into the kinetic energy of the supernova ejecta.