The emission geometry of pulsars with interpulses

We present polarization profiles of 23 pulsars exhibiting interpulse (IP) emissions using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). By applying the rotating vector model (RVM), we measured the inclination and impact angles for 16 pulsars, allowing us to investigate their beam geometries. Our analysis indicates that for 5 pulsars, the IP emissions likely originate from the same magnetic pole as the main pulse (MP), whereas for the remaining 11 pulsars, the IP and MP emissions originate from opposite magnetic poles. For the 7 pulsars that do not conform to the RVM, we are unable to determine whether the IP emissions originate from the same or opposite magnetic pole as the MPs. By analyzing the beam configurations of pulsars, we found that the emission within the beam is not fully active across both longitude and latitude. Filling factors ranging from 0.27 to 0.99 were obtained for pulsars with opposite pole IP emissions, suggesting an underestimation of emission height when applying the geometrical method. The emissions for MPs and IPs occur at different heights in the pulsar magnetosphere, with the difference in emission height ranging from tens to thousands of kilometers. We also found that some pulsars have wide emission beams, indicating that radio emissions may occur in regions of high altitude within the pulsar magnetosphere.