METERWAVELENGTH SINGLE-PULSE POLARIMETRIC EMISSION SURVEY. II. THE PHENOMENON OF DRIFTING SUBPULSES

Abstract

ABSTRACT A large sample of pulsars was observed as part of the Meterwavelength Single-pulse Polarimetric Emission Survey. We carried out a detailed fluctuation spectral analysis that revealed periodic features in 46% of pulsars, including 22 pulsars where drifting characteristics were reported for the first time. The pulsar population can be categorized into three distinct groups: pulsars that show systematic drift motion within the pulse window, pulsars showing no systematic drift but periodic amplitude fluctuation, and pulsars with no periodic variations. We discovered the dependence of the drifting phenomenon on the spin-down energy loss ( E ˙ ), with the three categories occupying distinctly different regions along the E ˙ axis. The estimation of the drift periodicity (P 3) from the peak frequency in the fluctuation spectra is ambiguous due to the aliasing effect. However, using basic physical arguments we were able to determine P 3 in pulsars showing systematic drift motion. The estimated P 3 values in these pulsars were anti-correlated with E ˙ , which favored the partially screened gap model of the inner acceleration region in pulsars.