The binary origin of pulsar velocities

Abstract

Analysis of a sample of pulsar proper-motions leads to the conclusion that most pulsars were born in and released from binary systems. A minority of pulsars belong to a class characterized by low velocities and low magnetic fields. These were significantly spun-up by accretion and released from the binary through a nonexplosive disruption of the companion. The rest belong to the high-velocity, high-magnetic field class. Using relations between the speeds at present and those in the binary orbit prior to its disruption, it is shown that such binaries must have undergone a common envelope phase of stellar evolution. The limits obtained on the masses and separations of these binary systems conform closely with those from stellar-evolution theory.