Pair creation above pulsar polar caps - Geometrical structure and energetics of slot gaps

Abstract

For the case of steady, space charge-limited flow occurring in a narrow polar flux tube that is bounded by high conductivity regions and negligible flow, a theory of pair creation over the polar caps of isolated, magnetized, rotating neutron stars whose magnetic axis is oblique to the rotation axis is developed. In short period objects with simple magnetic structure near the star, the particle acceleration power generated is found to be on the order of a few tenths of a per cent of the total spindown energy loss. This explains all the photon emission from the Crab and Vela pulsars, most of whose energy is generated in the slot gap. In long period objects with complex surface fields, the power generated in particle acceleration is comparable to the total spindown energy loss rate and is mostly created in the low altitude gap region between the star and the pair plasma.