We present a scenario ( SupraNova ) for the formation of GRBs occurring when a supramassive neutron star ( SMNS ) loses so much angular momentum that centrifugal support against self–gravity becomes impossible , and the star implodes to a black hole .
This may be the baryon–cleanest environment proposed so far , because the SN explosion in which the SMNS formed swept the medium surrounding the remnant , and the quickly spinning remnant loses energy through magnetic dipole radiation at a rate exceeding its Eddington luminosity by some four orders of magnitude .
The implosion is adiabatic because neutrinos have short mean free paths , and silent , given the prompt collapse of the polar caps .
However , a mass M _ { l } \approx 0.1 M _ { \odot } in the equatorial belt can easily reach centrifugal equilibrium .
The mechanism of energy extraction is via the conversion of the Poynting flux ( due to the large–scale magnetic field locked into the minitorus ) into a magnetized relativistic wind .
Occasionally this model will produce quickly decaying , or non–detectable afterglows .