Long-term Observations of Three Nulling Pulsars

TL;DR

This study analyzes 14.7 years of pulsar observations revealing long-term nulling, emission variability, and spin-down rate changes, providing insights into pulsar emission states and nulling behavior.

Contribution

It presents the first long-term observational analysis of nulling pulsars, identifying weak emission states and variability in nulling fractions over years.

Findings

All pulsars exhibit long-term nulls and emission phases.

PSR J1717-4054 shows short nulls and burst phases modulating detection.

PSR J1853+0505 has a weak emission state below detection thresholds.

Abstract

We present an analysis of approximately 200 hours of observations of the pulsars J1634$-$5107, J1717$-$4054 and J1853$+$0505, taken over the course of 14.7 yr. We show that all of these objects exhibit long term nulls and radio-emitting phases (i.e. minutes to many hours), as well as considerable nulling fractions (NFs) in the range $\sim67\,\% - 90\,\%$. PSR J1717$-$4054 is also found to exhibit short timescale nulls ($1 - 40~P$) and burst phases ($\lesssim 200~P$) during its radio-emitting phases. This behaviour acts to modulate the NF, and therefore the detection rate of the source, over timescales of minutes. Furthermore, PSR J1853$+$0505 is shown to exhibit a weak emission state, in addition to its strong and null states, after sufficient pulse integration. This further indicates that nulls may often only represent transitions to weaker emission states which are below the sensitivity thresholds of particular observing systems. In addition, we detected a peak-to-peak variation of $33\pm1\,\%$ in the spin-down rate of PSR J1717$-$4054, over timescales of hundreds of days. However, no long-term correlation with emission variation was found.