Gamma Ray Bursts from delayed collapse of neutron stars to quark matter stars

摘要

We propose a model to explain how a Gamma Rays Burst can take place days oryears after a supernova explosion. Our model is based on the conversion of apure hadronic star (neutron star) into a star made at least in part ofdeconfined quark matter. The conversion process can be delayed if the surfacetension at the interface between hadronic and deconfined-quark-matter phases istaken into account. The nucleation time (i.e. the time to form a critical-sizedrop of quark matter) can be extremely long if the mass of the star is small.Via mass accretion the nucleation time can be dramaticaly reduced and the staris finally converted into the stable configuration. A huge amount of energy, ofthe order of 10$^{52}$--10$^{53}$ erg, is released during the conversionprocess and can produce a powerful Gamma Ray Burst. The delay between thesupernova explosion generating the metastable neutron star and the new collapsecan explain the delay proposed in GRB990705 and in GRB011211.