2014ApJ...780L...5C

We explore the analogy between a rotating magnetized black hole and an axisymmetric pulsar and derive the black hole's electromagnetic spindown after its formation in the core collapse of a supermassive star. The spindown shows two characteristic phases: an early Blandford-Znajek phase that lasts a few hundred seconds and a late pulsar-like afterglow phase that lasts much longer. During the first phase, the spindown luminosity decreases almost exponentially, whereas during the afterglow phase it decreases as t ^–a with 1 ≲ a ≲ 1.5. We associate our findings with long duration gamma-ray bursts and compare them with observations.