A study of periodic nulling in PSR B0751+32 with FAST

TL;DR

This study investigates the periodic nulling behavior of pulsar PSR B0751+32 using FAST, revealing variable nulling periodicity, stable pulse components post-burst onset, and challenging existing geometric nulling models.

Contribution

The paper provides new measurements of nulling fraction and periodicity, demonstrating temporal evolution and stability of pulse components, and refutes previous subpulse drifting reports.

Findings

Nulling fraction is approximately 35.1%.

Nulling periodicity varies over time and sessions.

No evidence of subpulse drifting was found.

Abstract

We report new results from a nulling study of PSR~B0751+32 (PSR J0754+3231), observed at 1250~MHz with the Five hundred meter Aperture Spherical radio Telescope (FAST). Our analysis confirms the presence of periodic nulling in this pulsar. Using the recently developed mixture model method, we obtained a nulling fraction (NF) of $35.1\% \pm 0.6\%$. Three independent approaches were employed to estimate the nulling periodicity, and the results reveal significant temporal evolution of the modulation both within individual observations and across different \textbf{observing} essions. The pulsar exhibits an asymmetric two-component mean pulse profile, with the leading component brighter and narrower than the trailing one. Pulse energy analysis shows that both components remain stable immediately after the onset of the burst state, but subsequently undergo a progressive decline, with the trailing component most severely affected prior to burst termination. Notably, no evidence of the previously reported subpulse drifting was detected in our data. Our results challenge previous models that ascribed periodic nulling to purely geometric effects.