Subpulse Drifting and Periodic Nulling in single pulse emission of PSR B2000+40

TL;DR

This study analyzes single pulse emissions from pulsar B2000+40, revealing distinct periodicities linked to subpulse drifting and nulling, with their behaviors varying over time and differing in physical origin.

Contribution

It provides the first detailed analysis of subpulse drifting and nulling coexistence in a pulsar with core emission, highlighting their distinct physical mechanisms.

Findings

Detected two main periodicities at 2.5$P$ and 40$P$.

Subpulse drifting absent in the core component.

Nulling associated with longer periodicity.

Abstract

We have carried out a detailed study of single pulse emission from the pulsar B2000+40 (J2002+4050), observed at 1.6 GHz frequencies using the Effelsberg radio telescope. The pulsar has three components which are not well separated, with the central component resembling core emission. We have investigated modulations in single pulse behaviour using the fluctuation spectral analysis which showed presence of two prominent periodicities, around 2.5$P$ and 40$P$, respectively. The shorter periodicity was associated with the phenomenon of subpulse drifting and was seen to be absent in central core component. Drifting showed large phase variations in conal components. Additionally, the periodic modulations had significant evolution with time, varying between very sharp and highly diffuse features. In addition to drifting the pulsar also had presence of nulling in the single pulse sequence. The longer periodic feature in the fluctuation spectra was associated with nulling behaviour. The pulsar joins a select group which shows the presence of phase modulated drifting as well as periodic nulling in the presence of core emission. This provides further evidence for the two phenomena to be distinct from each other with different physical origin.