Discovery and Follow-up of a Quasiperiodically Nulling and Subpulse Drifting Pulsar with the Murchison Widefield Array

Abstract

The phenomenon of pulsar nulling, where pulsars temporarily and stochastically cease their radio emission, is thought to be indicative of a “dying” pulsar, where radio emission ceases entirely. Here we report the discovery of a long-period pulsar, PSR J0452−3418, from the ongoing Southern-sky MWA Rapid Two-meter pulsar survey. The pulsar has a rotation period of ∼1.67 s and a dispersion measure of 19.8 pc cm ^−3 , and it exhibits both quasiperiodic nulling and subpulse drifting. Periodic nulling is uncommon, reported in only <1% of the pulsar population, with even a smaller fraction showing periodic nulling and subpulse drifting. We describe the discovery and follow-up of the pulsar, including a positional determination using high-resolution imaging with the upgraded Giant Metrewave Radio Telescope (uGMRT), initial timing analysis using the combination of Murchison Widefield Array (MWA) and uGMRT data, and detailed characterization of the nulling and drifting properties in the MWA’s frequency band (140–170 MHz). Our analysis suggests a nulling fraction of 34% ± 6% and a nulling periodicity of ${42}_{-1.3}^{+1.5}$ pulses. We measure the phase ( P _2 ) and time modulation ( P _3 ) caused by the subpulse drifting, with an average P _2 of 7.1 ${}_{-3.1}^{+26.3}$ degrees and a P _3 of 4.8 ${}_{-0.9}^{+1.5}$ pulses. We compare and contrast the observed properties with those of other pulsars that exhibit subpulse drifting and quasiperiodic nulling phenomena, and find that the majority of these objects tend to be in the “death valley” in the period–period derivative ( P – $\dot{P}$ ) diagram. We also discuss some broader implications for pulsar emission physics and the detectability of similar objects using next-generation pulsar surveys.

Keywords

• Pulsars
• Radio pulsars
• Time domain astronomy
• High energy astrophysics