Coherent Inverse Compton Scattering Responsible for Pulsar Polarized and Unpolarized Emission

A coherent inverse Compton scattering (ICS) mechanism is used to get polarization properties of radio emission of pulsars. It is found that particles moving along a ring with radius θ' = l/(√3γ)simultaneously contribute via coherent ICS. The circular polarization can be easily gotten as well as linear polarization at the same time. Our theory releases the upper limit of Lorentz factor γ≤20 put by curvature radiation, and γ may take several thousands in ICS. firtherrnore, subpulse position angles do take diverse values, while mean position angle is associated with the projection of magnetic field lines. So it is natural to get commonly-seen S-shaped swing of mean position angles. Finally we present a simulation for position angle rotation, linear polarization, circular polarization of PSR1508+55, which means that the coherent ICS may be responsible for radio emission.