The shape of pulsar radio beams

All available data on the mean pulse profiles of pulsars and their polarization, including a large body of previously unpublished material, have been analysed in order to determine the two-dimensional form of the radio beams emitted by pulsars. The differing properties of core and conal emission discussed by a previous author are confirmed but it is suggested that the observations are best described by a gradual change in emission characteristics from the core or axial region to the outer edge of the emission beam rather than two distinct emission processes. The spectral index difference between the core and conal regions is shown to be a function of pulsar period and is greatest for short-period pulsars. (author)