Polarimetric Observations of PSR J0614+2229 and PSR J1938+2213 Using FAST

Abstract

We presented observations of PSRs J0614+2229 and J1938+2213 using the Five-hundred-meter Aperture Spherical radio Telescope. PSR J0614+2229 shows two distinct emission states, in which the emission of state A occurs earlier than that of state B in longitude. The phase offset between the average pulse profile peaks of the two states is about 1.°05. The polarization properties of the average pulse profile of the two states are different with different linear position angle swings. We found that the emission becomes brighter during the transition between the two states, which has never been seen in other mode-changing pulsars before. PSR J1938+2213 appears to consist of a weak emission state superposed by brighter burst emissions. The weak state is always present and the energy of the strongest pulse in the burst state is about 57 times larger than that of the average pulse energy. The polarization properties of the two states are also different, and orthogonal polarization modes can be seen only in the burst state, rather than both states. Our results suggest that, for the two pulsars, the emissions of the two states may be generated in different regions in the pulsar magnetosphere.