Radio Pulsar Death Line Revisited: Is PSR J2144-3933 Anomalous?

Abstract

We reinvestigate the radio pulsar ``death lines'' within the framework of two different types of polar cap acceleration models, i.e., the vacuum gap model and the space-charge-limited flow model, with either curvature radiation or inverse Compton scattering photons as the source of pairs. General relativistic frame-dragging is taken into account in both models. We find that the inverse Compton scattering induced space-charge-limited flow model can sustain strong pair production in some long-period pulsars, which allows the newly detected 8.5s pulsar PSR J2144-3933 to be radio loud, without assuming a special neutron star equation-of-state or ad hoc magnetic field configurations.Comment: replaced to meet the final version published in ApJ, 531, L135. The main revision is the discussion about the pulsar polar cap surface magnetic field, which reads $6.4\times 10^{19} \sqrt{P \dot P}$ regardless of the internal field structure (point dipole or uniformly magnetized interior). Therefore different assumptions of the internal magnetic fields have no infuence on the location of the deathline