Radio pulsar death line revisited: Is PSR J2144-3933 anomalous?

We reinvestigate the radio pulsar death lines within the framework of two different types of the 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 8.5 s pulsar PSR J2144-3933 to be radio loud without assuming special neutron star equations of state or ad hoc magnetic field configurations.