A Review of Galactic Millisecond Pulsar Searches

Abstract

Since the discovery of the first millisecond pulsar in 1982, the main discoveries of more of these exotic objects have come in two bursts. The first followed the realization late in the decade that they might be formed readily in globular clusters and resulted in the discovery of about two dozen objects in these clusters between 1987 and 1990. The second burst started shortly after this as improved computer technology permitted widespread searches of the Galaxy with high sensitivity and is continuing at the present time. This paper describes the main successful surveys for these galactic millisecond pulsars of which 29 are now known. 21 of these are in circular orbits with low-mass companion stars. The large number of objects now available allows a number of firm statistical trends to be seen which all point to an evolutionary phase of these systems involving the spin-up of old neutron stars during the accretion of matter from less evolved companions during their giant phase. Surveys of the present generation are still very insensitive to short period pulsars or highly accelerated pulsars in close or massive binary systems, limitations which should be removed in future years.