Meterwavelength Single-Pulse Polarimetric Emission Survey. Ii. The Phenomenon of Drifting Subpulses

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 which revealed periodic features in 46% pulsars including 22 pulsars where drifting characteristics were reported for the first time. The pulsar population can be categorized into three distinct groups, pulsars which show systematic drift motion within the pulse window, the 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 (Ė), with the three categories occupying distinctly different regions along theĖ 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 withĖ which favoured the Partially Screened Gap model of Inner Acceleration Region in pulsars.

On Nulling, Drifting, and Their Interactions in PSRs J1741–0840 and J1840–0840

“…Further observations at 300 MHz by Weltevrede et al (2007) revealed two P 3 values of 4.8±0.1 and 4.7±0.1 periods which were not possible to separate between the two components due to the sensitivity of their observations. Moreover, Basu et al (2016) have confirmed the 4.7±0.6 periods feature at 325 MHz and the 4.8±0.6 periods feature at 610 MHz. Here, we report its detailed behavior at 625 MHz with longer observations in contrast to Basu et al (2016).…”

“…Moreover, Basu et al (2016) have confirmed the 4.7±0.6 periods feature at 325 MHz and the 4.8±0.6 periods feature at 610 MHz. Here, we report its detailed behavior at 625 MHz with longer observations in contrast to Basu et al (2016). PSR J1840−0840 was discovered during the recent searches conducted from the Parkes telescope (Lorimer et al 2006).…”

“…In other words, the apparent P 3 differences could simply be due to rapidly changing driftband slopes. Furthermore, Basu et al (2016) have also suggested that in a few instances P 3 measurements could cause ambiguity due to aliasing, which eventually hinders our understanding in connecting the observed behavior with the actual physical phenomena. Recently, McSweeney et al (2017) also indicated that different P 3 modes seen in PSR B0031−07 were actually gradual changes in the driftband slopes.…”

“…Weltevrede et al (2007) have also reported a low frequency excess in their fluctuation spectra for PSR J1741−0840, however, no measurements was reported with possible quasi- periodicity of burst bunching. In more recent study, Basu et al (2016) conducted observations of PSR J1741−0840 and reported drifting periodicities at 325 MHz and 610 MHz. Among the reported drifting features, low frequency periodic components were also reported with 0.033±0.006 cycles/P 1 and 0.033±0.009 cycles/P 1 at 325 MHz and 610 MHz, respectively.…”

“…Here, we report results for these pulsars from relatively longer observations, whose basic parameters are listed in Table 1. PSR J1741−0840 (PSR B1738−08) was discovered during the earlier searches (Manchester et al 1978) from the Molonglo telescope in Australia. It is a known drifting pulsar with a few studies (Weltevrede et al 2006(Weltevrede et al , 2007Basu et al 2016) reporting its abnormal drifting behavior. It displays two distinct profile components at 325 MHz.…”