1997A&A...324..981V

A major uncertainty in our understanding of pulsar emission physics is the location of the radio emission region in pulsar magnetospheres. The narrowing of the intensity profile width with increasing frequency has traditionally been taken as observational evidence supporting a radius-to-frequency mapping in pulsar magnetospheres. Here, 64 high-quality polarimetric profiles at cm-wavelengths have been analyzed to probe for the first time the emission radius at presumably deeper layers of pulsar magnetospheres. Interpreting polarization measurements in the context of the modified relativistic rotating-vector model (Blaskiewicz et al. 1991ApJ...370..643B), we derive emission altitudes and compare our results with the geometrical predictions of a rotating dipolar configuration. We conclude that for slow pulsars the emission is consistent with heights ranging between 1 and 2% of the light-cylinder radius. Only a slight radius-to-frequency mapping is evident at cm-wavelengths which saturates progressively with frequency. The consistency between the results of the two methods further supports the persistence of an undisturbed dipole field throughout the magnetospheres of slow pulsars.