Profile morphology and polarization of young pulsars

We present polarization profiles at 1.4 and 3.1 GHz for 14 young pulsars with characteristic ages less than 75 kyr. Careful calibration ensures that the absolute position angle of the linearly polarized radiation at the pulsar is obtained. In combination with previously published data, we draw three main conclusions about the pulse profiles of young pulsars. (i) Pulse profiles are simple and consist of either one or two prominent components. (ii) The linearly polarized fraction is nearly always in excess of 70 per cent. (iii) In profiles with two components, the trailing component nearly always dominates, only the trailing component shows circular polarization and the position angle swing is generally flat across the leading component and steep across the trailing component. Based on these results, we can make the following generalizations about the emission beams of young pulsars. (i) There is a single, relatively wide cone of emission from near the last open field lines. (ii) Core emission is absent or rather weak. (iii) The height of the emission is between 1 and 10 per cent of the light cylinder radius.