The polarisation of the drifting sub-pulses from PSR B1919+21

Aims. We aim to expand our understanding of radio wave emission and propagation in the pulsar magnetosphere by studying polarisation drifting sub-pulses highly sensitive observations PSR B1919+21 recorded at Arecibo Observatory. Methods. apply compare several methods analysis visualisation, including eigenvalue longitude-resolved covariances between Stokes parameters; scatter plots normalised vectors Poincaré sphere; auto- cross-correlations parameters as a function offset pulse longitude lag number; mean drift bands state, formed averaging quantities derived from them synchronously with sub-pulse modulation period. Results. observe regions where superposition orthogonally polarised modes is best described incoherent appears be least partially coherent. Within region coherent superposition, over range longitudes spanning ∼2°, distribution forms torus centered near origin sphere. Furthermore, rotate about axis revolution total intensity. Conclusions. The nearly uniform circular clearly evident both toroidal parameters, not predicted current theoretical models emission. propose different scenarios explain generation torus, based on either or phase-coherent modes.