Pulsar Radio Emission Geometry
Pulsar radio emission is belived to come from relativistic plasma accelerated along the dipolar magnetic field lines in pulsar magnetosphere. The beamed emission by relativistic sources occur in the direction of tangents to the field lines in the corotating frame, but in an inertial (lab) frame it is aberrated toward the direction of rotation. To receive such a beamed emission line-of-sight must align with the source velocity within the beaming angle 1/γ, where γ is the Lorentz factor of the source. By solving the viewing geometry, in an inclined and rotating dipole magnetic field, we find the coordinates of the emission region in corotating frame. Next, give a general expression for the phase shift in the intensity profile in lab frame by taking into account of aberration, retardation and polar cap currents.
By considering uniform and modulated emissions, we have simulated a few typical pulse profiles. The circular polarization of antisymmetric type is an intrinsic property of curvature radiation, and it survives only when there is modulation or discrete distribution in the emitting sources. Our model predicts a correlation between the polarization angle swing and antisymmetric circular polarization.
Key wordspulsars: general radiation mechanisms: nonthermal stars: magnetic fields geometry
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