Subpulse modulation, moding and nulling of the five-component pulsar B1737+13

Recent Arecibo polarimetric observations of the bright five-component pulsar B1737+13 have facilitated a comprehensive new analysis of its pulse-sequence modulation phenomena. The bright leading component in the star’s profile, as well as its other conal components, exhibit a roughly periodic, longitude-stationary modulation with an effective P3 of about nine rotation periods. We also find that they show a much slower periodicity at ∼92 rotation periods. Correlation analyses reiterate these regularities and suggest a modulation pattern moving through the profile negatively. These various properties are largely compatible with a rotating subbeam-carousel model having typically 10 ‘beamlets’. Polar maps are given showing typical subbeam structures that are compatible with the pulsar’s somewhat unstable modulation. Geometric analysis finds the central component lagging the centre of the traverse of the polarization position angle, suggesting possible effects of retardation and aberration. There remains little overt evidence for the two modes identified previously. Unlike B1237+25, this pulsar exhibits few if any true nulls, and its core emission is relatively steady.