Pulsars and neutron stars/History of the theoretical understanding of pulsars

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Introduction[edit | edit source]

In this section we first describe advances in the understanding of the interior of neutron stars, then the magnetosphere and emission and finally the pulsar population.

Glitches and the neutron star interior[edit | edit source]

Even before the discovery of the first pulsar, the existence of neutron stars had been predicted (Baade & Zwicky 1934). It was therefore clear that neutron stars are "made up of neutrons", but it wasn't until the discovery of the first glitch in the vela pulsar that it became possible to directly probe the interior of a neutron star. Baym, Pethick & Pines (1969) showed that matter in the interior of a typical neutron star is a mixture of three degenerate interacting quantum liquids — neutrons, protons and electrons with the neutrons dominating. They suggested that this mixture would be bounded on the inside by a superdense core and on the outside by a solid mantle. They suggested that there would be superfluid states in the interior. They (Baym et al. 1969) then noted that if the glitch in the Vela pulsar was caused by a "star quake" then the event demonstrates that the interior of the pulsar is a superfluid. Their model was able to explain the sudden change in spin-frequency and also the characteristic relaxation of a glitch after the event.

Pines & Alpar (1984) provided a review related to superfluidity in the Vela, Crab and PSR B0525+21 and discussed the possibility of superfluidity in the millisecond pulsar population.

Pines (1974) showed how observations of pulsars wobbling (free-precession) can be used to study the structure and properties of the associated neutron star.

The pulsar emission and geometry[edit | edit source]

The population of neutron stars and pulsars[edit | edit source]