The pulsar kick velocity distribution

Abstract

We analyse the sample of pulsar proper motions, taking detailed account of the selection effects of the original surveys. We treat censored data using survival statistics. From a comparison of our results with Monte Carlo simulations, we find that the mean birth speed of a pulsar is ~250-300 km s^(-1), rather than the 450 km s^(+1) found by Lyne & Lorimer. The resultant distribution is consistent with a Maxwellian with dispersion σ_v = 190 km s^(-1) . Despite the large birth velocities, we find that the pulsars with long characteristic ages show the asymmetric drift, indicating that they are dynamically old. These pulsars may result from the low-velocity tail of the younger population, although modified by their origin in binaries and by evolution in the galactic potential.