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Session 74 - Pulsars.
Display session, Wednesday, January 15
Metropolitan Ballroom,

[74.02] The Distribution of Pulsar Velocities

B. M. S. Hansen (CITA), E. S. Phinney (Caltech)

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 \sim 250-300 \, km \, s^-1, rather than the 450 km s^-1 found by Lyne amp; Lorimer (1995). The resultant distribution is consistent with a maxwellian of dispersion \sigma_v = 190 \, km \, s^-1. Despite the large birth velocities, we find that the pulsars with long spin-down 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.

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