| Abstract
| - Strong magnetic fields modify particle motion in the curved space-time of spinning black holes and change the stability conditions of circular orbits. We study conditions for magnetocentrifugal jet launching from accretion discs around black holes, whereby large-scale black hole lines anchored in the disc may fling tenuous coronal gas outwards. For a Schwarzschild black hole, magnetocentrifugal launching requires that the poloidal component of magnetic fields makes an angle less than 60° to the outward direction at the disc surface, similar to the Newtonian case. For prograde rotating discs around Kerr black holes, this angle increases and becomes 90° for footpoints anchored to the disc near the horizon of a critically spinning a=M black hole. Thus, a disc around a critically spinning black hole may centrifugally launch a jet even along the rotation axis.
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