Extended Acceleration in Slot Gaps and Pulsar High‐Energy Emission

We revise the physics of primary electron acceleration in the "slot gap" (SG)above the pulsar polar caps (PCs), a regime originally proposed by Arons andScharlemann (1979) in their electrodynamic model of pulsar PCs. We employ thestandard definition of the SG as a pair-free space between the last open fieldlines and the boundary of the pair plasma column which is expected to developabove the bulk of the PC. The rationale for our revision is that the propertreatment of primary acceleration within the pulsar SGs should take intoaccount the effect of the narrow geometry of the gap on the electrodynamicswithin the gap and also to include the effect of inertial frame dragging on theparticle acceleration. The combination of the effects of frame dragging andgeometrical screening in the gap region naturally gives rise to a regime ofextended acceleration, that is not limited to "favorably curved" field lines asin earlier models, and the possibility of multiple-pair production by curvaturephotons at very high altitudes, up to several stellar radii. The estimatedtheoretical high-energy luminosities of the SG cascade radiation are in goodagreement with the corresponding empirical relationships for gamma-ray pulsars.We illustrate the results of our modeling of the pair cascades and gamma-rayemission from the high altitudes in the SG for the Crab pulsar. The combinationof the frame-dragging field and high-altitude SG emission enables bothacceleration at the smaller inclination angles and a larger emission beam, bothnecessary to produce widely-spaced double-peaked profiles.Comment: 24 pages, accepted for publication in Astrophysical Journal, Version 2 has corrected expressions for high-B cas