Cosmological gamma-ray bursts (GRBs) appear as the brightest transient phenomena in the Universe. The nature of their central engine is a missing link in the theory of fireballs to stellar mass progenitors, and may be associated with low mass black holes. In contact with an external magnetic field $B$, black hole spin produces a gravitational potential on the wave function of charged particles. We show that a rapidly rotating black hole of mass $M$ produces outflow from initially electrostatic equilibrium with normalized isotropic emission $\sim {10}^{48}\left(B/B_c{)}^2\right(M/{7M}_{\odot }{)}^2{sin}^2\theta \mathrm{erg}/\mathrm{s}$, where $B_c=4.4\mathrm{}\times {10}^{13}\mathrm{G}$. The half-opening angle satisfies $\theta \ge \sqrt{B_c/3B}$. The outflow proposed as input to GRB fireball models.

• Received 26 August 1999

DOI:https://doi.org/10.1103/PhysRevLett.84.3752