densities than the lighter neutron stars. As these massive neutron stars spin down through dipole electromagnetic and quadruple gravitational radiations, the centrifugal force gets smaller and the central density could be increased high enough for a QCD phase transition, and the neutron stars will also inevitably be converted to strange stars[^2].

To sum up, the energy budget problem of the core-collapse supernova paradigm seems to require extra neutrino sources, and the phase transition from neutron matter to SQM is a natural mechanism to cure the imperfection of the paradigm. For the progenitors with negligible effect of rotation, additional neutrino emission of phase transition could sufficiently enhance the power of neutrino energy deposition behind the stalled shock to retain a successful explosion and its enough energy, with a strange star directly formed after the explosion. For the progenitors with rapidly rotating inner core, neutron stars might be formed as semi-products after the explosions, but such neutron stars will be finally phase-converted to strange stars when they spin down enough. Thus, it is plausible that at least some known radio pulsars may be in fact strange stars rather than neutron stars. Firm conclusions could not be drawn at present stage due to 