Pulsar velocities and their origins

Abstract

The review covers the history of the measurements of pulsar velocities and the attempts to interpret them. Various correlations observed or claimed between the velocities and other pulsar properties are discussed and their relevance assessed. The picture one seems to be converging towards is that most pulsars come from binaries, roughly half of them when released have "orbital" velocities, and the others - the new born ones - have velocities that are a combination of orbital plus "kick" velocities. The physical origin of the kicks is obscure, but their existence seems well founded on observational grounds. An important offshoot of the attempts to understand pulsar velocities is the hypothesis, also made on other grounds, that the evolution of neutron star magnetic fields is intimately related to their rotational histories.