2005ApJ...628..923G

The radiation by relativistic plasma particles is beamed in the direction of field-line tangents in the corotating frame, but in an inertial frame it is aberrated toward the direction of rotation. We have revised the relation of aberration phase shift by taking into account the magnetic colatitude and azimuth of the emission spot and the plasma rotation velocity. In the limit of the small-angle approximation, the aberration phase shift becomes independent of the inclination angle α and the sight line impact angle β. However, at larger altitudes or larger rotation phases, the shift does depend on α and β. We have given an expression for the phase shift in the intensity profile by taking into account aberration, retardation, and polar cap currents.