PSR B0943+10: Mode Switch, Polar Cap Geometry, and Orthogonally Polarized Radiation

Abstract

As one of the paradigm examples to probe into pulsar magnetospheric dynamics, PSR B0943+10 (J0946+0951) manifests representatively, showing a mode switch, orthogonal polarization, and subpulse drifting, frequently studied below 600 MHz. Here, both integrated and single pulses are studied at a high frequency (1.25 GHz) with FAST. The mode switch is studied using a profile decomposition method. A phase space evolution for the pulsar’s mode switch shows a strange-attractor-like pattern. The radiative geometry is proposed by fitting polarization position angles with the rotating vector model. The pulsar pulse profile is then mapped to the sparking locations on the pulsar surface, and the differences between the main pulse’s and the precursor component’s radiative processes may explain the X-ray’s synchronization with radio mode switch. Detailed single pulse studies on B0943+10's orthogonally polarized radiation are presented, which may support certain models of radiative transfer of polarized emission. In particular, the difference in orthogonal polarization modes’ circular polarization might reflect the cyclotron absorption in pulsar magnetospheres. B0943+10's B and Q modes evolve differently with frequency and have different proportions of orthogonal modes, which indicates possible magnetospheric changes during mode switch. For Q mode pulse profile, the precursor and the main pulse components are orthogonally polarized, and are probably originated from different depths in the magnetosphere. The findings could impact significantly on the pulsar electrodynamics and the radiative mechanism related.