Radio pulsars and the scale height of ionized hydrogen

Abstract

Some recently advanced models for the decay of the magnetic fields of neutron stars imply that functioning radio pulsars should be present at distances z in excess of 1 kpc from the galactic plane, contrary to the apparent z-distribution of known pulsars. The present upper bound of the apparent z-distribution may well be an artifact of the use of the dispersion measures to determine distances to pulsars. Dispersion measures of pulsars in globular clusters imply that the ionized gas responsible for the dispersion of pulsar signals has a scale height of about 500-1000 pc. This would lead to an underestimation of the distances of pulsars far away from the galactic plane. Pulsars currently thought to be located at z of less than about 1 kpc may in fact be at higher z.