Some constraints on the evolutionary history of the binary pulsar PSR 1913+16

Abstract

It is argued that the combination of 0.059 s pulse period and weak surface dipole magnetic field strength of PSR 1913 + 16 is excluded for a newly born pulsar. This yields support to the suggestion that PSR 1913 + 16 obtained its short pulse period during a spiral-in history, in which it underwent heavy accretion of matter with angular momentum from its companion. The shortest possible pulse period compatible with its magnetic field in such a case is approximately 0.04 s. As this spiral-in will have completely circularized the orbit, its presently large orbital eccentricity indicates that a second supernova explosion must have taken place in the system and, consequently, that its companion is also a neutron star (or a black hole). It is argued that the progenitor system was a binary with component masses of at least 8 solar masses. The various possible types of radio pulsars resulting from the evolution of close binaries are discussed.