Baryon-poor outflows from rotating black holes

Cosmological gamma-ray bursts are probably powered by systems harboring a rotating black hole. We show that frame-dragging creates baryon-poor outflows in a differentially rotating gap along an open magnetic flux-tube with dissipation $P=\Omega_T(\Omega_H-2\Omega_T)A_\phi^2$, where $2\pi A_\phi$ denotes the flux in the open tube, for angular velocities $\Omega_H$ and $\Omega_T$ of the black hole and the torus, respectively. The output in photon-pair outflow will be reprocessed in an intervening hypernova progenitor wind or the ISM.