Pulsar Birthrates from the Parkes Multibeam Survey

Abstract

We investigate the pulsar birthrate from a sample of 815 nonrecycled pulsars detected by the Parkes multibeam survey, accounting as accurately as possible for all known selection effects. We find that pulsars with magnetic fields greater than G account for more than half of the total birthrate in spite of comprising only 12 2.5 # 10 about 5%–10% of the total Galactic population. While we do not find evidence for a significant population of pulsars “injected” into the population with spin periods of ∼0.5 s, we do find that many, perhaps 40%, are born with periods in the range 0.1–0.5 s. The absolute number and birthrate of Galactic pulsars is strongly dependent on the assumed models for pulsar beaming and Galactic electron distribution. Adopting the most recent models, we find the total pulsar birthrate to be between 0.9 and 1.9 pulsars per century for 1400 MHz luminosities greater than 1 mJy kpc 2 , and the total Galactic population of active radio pulsars above this luminosity limit to be between 70,000 and 120,000. Subject headings: pulsars: general — stars: evolution