On the aberration-retardation effects in pulsars

TL;DR

This study investigates aberration-retardation effects in pulsars by analyzing multi-frequency profiles, finding that these effects are likely common and imply the core emission originates below the conal region.

Contribution

The paper provides observational evidence for aberration-retardation effects in a sample of 23 pulsars, supporting models of emission height differences.

Findings

7 pulsars show clear A/R effects

12 pulsars show tendencies towards A/R effects

4 pulsars are counterexamples

Abstract

The magnetospheric locations of pulsar radio emission region are not well known. The actual form of the so--called radius--to--frequency mapping should be reflected in the aberration--retardation (A/R) effects that shift and/or delay the photons depending on the emission height in the magnetosphere. Recent studies suggest that in a handful of pulsars the A/R effect can be discerned w.r.t the peak of the central core emission region. To verify these effects in an ensemble of pulsars we launched a project analysing multi--frequency total intensity pulsar profiles obtained from the new observations from the Giant Meterwave Radio Telescope (GMRT), Arecibo Observatory (AO) and archival European Pulsar Network (EPN) data. For all these profiles we measure the shift of the outer cone components with respect to the core component which is necessary for establishing the A/R effect. Within our sample of 23 pulsars 7 show the A/R effects, 12 of them (doubtful cases) show a tendency towards this effect, while the remaining 4 are obvious counter examples. The counter--examples and doubtful cases may arise from uncertainties in determination of the location of the meridional plane and/or the core emission component. It hence appears that the A/R effects are likely to operate in most pulsars from our sample. We conclude that in cases where those effects are present the core emission has to originate below the conal emission region.