Millisecond Pulsar Formation and Evolution

Abstract

The evolutionary history of binary radio pulsars, including the two millisecond binary pulsars, is reviewed. There are two groups of binary pulsars, the PSR 1913+16-group, which descended from massive X-ray binaries, and the PSR 1953+29-group, which descended from fairly wide low-mass X-ray binaries. The neutron stars in the second group probably formed by the accretion-induced collapse of a massive white dwarf. The companion stars in both groups of systems are expected to be dead stars, i.e. white dwarfs or neutron stars. The large total number of millisecond binary pulsars in the galaxy (∼ 10 4 ), indicates that magnetic fields of neutron stars do not decay below a value of order 10 9 G. Possible explanations for this phenomenon are discussed. Coalescence with a close degenerate companion provides a viable model for the formation of the single millisecond pulsar.