KERR PARAMETERS FOR STELLAR MASS BLACK HOLES AND THEIR CONSEQUENCES FOR GRBS AND HYPERNOVAE

Recent measurements of the Kerr parameters a⋆ for two black-hole binaries in our Galaxy (Shafee et al. 2006), GRO J1655−40 and 4U 1543−47 of a⋆ = 0.65 − 0.75 and a⋆ = 0.75 − 0.85, respectively, fitted well the predictions of Lee et al. (2002), of a⋆ ∼ 0.8. In this report we also note that Lee et al. (2002) predicted a⋆ > 0.5 for 80% of the Soft X-ray Transient Sources. The maximum available energy in the Blandford-Znajek formalism for a⋆ > 0.5 gives E > 3 × 10 53 ergs, orders of magnitude larger than the energy needed for the GRB and hypernova explosion. We interpret the Soft X-ray Transients to be relics of GRBs and Hypernovae, but most of them were subluminous ones which could use only a small part of the available rotational energy. Subject headings: binaries: close — gamma rays: bursts — black hole physics — supernovae: general — X-rays: binaries