Radio Pulsars in an Electromagnetic Universe

Abstract

The vacuum and plasma magnetosphere of neutron stars (NSs) in an electromagnetic universe (EU) were studied. First, we found vacuum solutions of the Maxwell equation for the electromagnetic field of rotating magnetized NSs in the slow-rotation approximation and analyzed the effects of the EU parameter on magnetic field components. It has been shown that in the presence of the EU field, the magnetic field lines near the star become denser and stronger compared with the case of GR. The Goldreich–Julian (GJ) charge density as a source of induced electric field was calculated. Our analyses showed that the GJ charge density increases with the increase in the EU parameter, while the size of the polar cap of NSs decreases. The solutions of Poisson equation for the scalar electric field have also been obtained at near and far zones. It has been shown that the parallel accelerating electric field increases in presence of the EU. We have also analyzed the effects of the EU on the death line for radio pulsars and shown that the position of the death line in the P−P˙ diagram shifts up. Finally, we investigated the energy losses of rotating NSs due to electromagnetic radiation. It was obtained that at a critical value of the EU parameter, which depends on the compactness parameter, the luminosity of electromagnetic radiations of magnetospheric radiation increases about 106 times.