The Branching Ratio of Type Ib/c Supernovae to Gamma-Ray Burst Supernovae

We study centered and decentered nucleation of black holes in core-collapseof massive stars in binaries. By Bekenstein's gravitational-radiation recoilmechanism, a newly nucleated black hole typically leaves the central coreprematurely. With low probability, the black hole remains centered and maturesto a high-mass black hole which spins rapidly if the binary is compact.GRB030329/SN2003dh demonstrates that Type Ib/c supernovae are the parentpopulation of long GRBs, whose branching ratio is ${\cal R}=(2-4)\times10^{-3}$. We identify ${\cal R}$ with the low probability of centerednucleation in compact binaries. Decentered events are predicted to produce asingle short burst in gravitational radiation. Centered events are predicted toproduce a second, long-burst in gravitational radiation powered by a luminousblack hole. These signatures are of interest to LIGO, VIRGO and TAMA.Comment: to appear in ApJ Let