Revisiting the carousel and non-radial oscillation models for pulsar B0809+74

Recent interest in pulsar B0809+74, well known for its highly accurate drifting subpulses and ‘memory across nulls’ has raised questions about the adequacy of the rotating subbeam-carousel or/and non-radial oscillation models to describe this phenomenon. The success of the subbeam-carousel model in explaining the drift modes and periodic nulls in B1918+19 has encouraged us to revisit the application of this model to B0809+74. Pulsar B0809+74 is a complicated object, as are many pulsars where our sightline grazes the conal beam edge obliquely. Its subpulses also exhibit complex modal polarization, and only analysing the total power paints an incomplete picture of emission from the star. This remarkable pulsar has, however, been studied in great detail for over three decades, and many of the earlier controversies about its characteristics have largely been resolved. In this paper, we demonstrate that the carousel model is highly successful in reproducing the behaviour of B0809+74 in every heuristic and geometric manner. In addition, Rosen and Demorest have quantitatively fitted a non-radial oscillation model to B0809+74 at a single frequency, and we discuss how this model can reproduce the behaviour of B0809+74 across a much larger band.