2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/14264We investigate the possibility that gamma-ray bursts are powered by a central engine consisting of a black hole with an external magnetic field supported by a surrounding disk or torus. The rotational energy of the black hole can be extracted electromagnetically as a Poynting flux, a mechanism proposed by Blandford and Znajek(1977). Recently observed magnetars indicate that some compact objects have very high magnetic fields, up to $10^{15}$ G, which is required to extract the energy within the duration of a GRB, i.e., in 1000 s or less. We demonstrate also that the Poynting flux need not be substantially dominated by the disk.7 pages, no figure, paspconf.sty, to appear in Proceedings " Gamma Ray Bursts: The First Three Minutes", Gräftåvallen, Sweden, Feb. 6 - 11, 1999Astrophysicstext