The state of pulsar theory

Abstract

I summarize the status of pulsar theory, now 35 years after their discovery. Although progress has been made in understanding the relevant processes involved, there are several widely held misconceptions that are inhibiting further advances. These include the idea that plasma “must” be accelerated from the magnetic polar caps (the basis for the “Hollow Cone Model”) and the idea that winds would be driven away by centrifugal forces, with large amplitude electromagnetic waves playing no role whatsoever. However, recent theoretical work is converging on a picture that closely resembles the latest HST and Chandra images, providing hope for the future. No less than three groups have recently confirmed the early Krause-Polstorff–Michel simulations showing that the fundamental plasma distribution around a rotating neutron star consists of two polar domes and an equatorial torus of trapped nonneutral plasma of opposite sign charges. Unless a lot of new physics can be added, this distribution renders the Goldreich–Julian model irrelevant (i.e., along with most of the theoretical publications over the last 33 years).