Meterwavelength Single-pulse Polarimetric Emission Survey III: The Phenomenon of Nulling in Pulsars

TL;DR

This study analyzes nulling behavior in 36 pulsars, revealing short and long nulls, periodicities, and possible links to plasma processes, providing new insights into pulsar emission mechanisms.

Contribution

First comprehensive analysis of nulling in a large pulsar sample, identifying periodicities and their potential origins, advancing understanding of pulsar magnetospheric processes.

Findings

Nulls last less than five periods mostly, but some extend to hundreds of periods.

Periodicities in null-burst transitions found in 11 pulsars, linked to nulling behavior.

Nulling periodicities align with amplitude modulation, suggesting a common origin.

Abstract

A detailed analysis of nulling was conducted for the pulsars studied in the Meterwavelength Single-pulse Polarimetric Emission Survey. We characterized nulling in 36 pulsars including 17 pulsars where the phenomena were reported for the first time. The most dominant nulls lasted for short durations, less than five periods. The longer duration nulls extending to hundreds of periods were also seen in some cases. A careful analysis showed the presence of periodicities in the transition from the null to the burst states in 11 pulsars. In our earlier work fluctuation spectrum analysis showed multiple periodicities in 6 of these 11 pulsars. We demonstrate that the longer periodicity in each case was associated with nulling. The shorter periodicities usually originate due to subpulse drifting. The nulling periodicities were more aligned with the periodic amplitude modulation indicating a possible common origin for both. Most prevalent nulling lasts for a single period and can be potentially explained using random variations affecting the plasma processes in the pulsar magnetosphere. On the other hand, the longer duration nulls require changes in the pair production processes that need an external triggering mechanism for the change. The presence of periodic nulling puts an added constrain on the triggering mechanism which also needs to be periodic.