On the pulsar velocity–magnetic field correlation

Abstract

From a sample of 98 radio pulsarswith reliable kinematic measurements, we re-examine the evidencefor a correlation between the transverse speed V_t and the inferreddipole magnetic field strength B. We find the correlation to be onlymarginally significant and, most importantly, find no evidence for acorrelation amongst the pulsars younger than 3Myr. Since such pulsarsare relatively unaffected by spatial selection effects, we concludethat there is no causal V-B correlation. The trend seen by previousauthors amongst a smaller sample of predominantly older pulsars, and inthe old pulsars of the new sample, can largely be explained by therelatively short time-scales on which pulsars of high magnetic field loserotational kinetic energy, and hence radio luminosity, compared tothose with weaker magnetic fields. It is also possible that someweak magnetic field, low-velocity pulsars in the sample have had adifferent evolutionary history from the bulk of the population.