On the Pulse Intensity Modulation of PSR B0823+26

TL;DR

This study analyzes the complex nulling and emission behaviors of pulsar PSR B0823+26 over 153 days, revealing diverse nulling timescales, potential pre-ignition flickering, and minimal impact on spin-down rate, suggesting many pulsars may share similar properties.

Contribution

It provides the first detailed long-term analysis of PSR B0823+26's nulling behavior, linking short and long nulls, and constrains the impact of emission states on spin-down rate.

Findings

The pulsar exhibits both short and long nulls, indicating a range of nulling timescales.

No significant change in spin-down rate between emission modes, with an upper limit of 6%.

Evidence suggests possible pre-ignition flickering before steady emission.

Abstract

We investigate the radio emission behaviour of PSR B0823+26, a pulsar which is known to undergo pulse nulling, using an 153-d intensive sequence of observations. The pulsar is found to exhibit both short (~min) and unusually long-term (~hours or more) nulls, which not only suggest that the source possesses a distribution of nulling timescales, but that it may also provide a link between conventional nulling pulsars and longer-term intermittent pulsars. Despite seeing evidence for periodicities in the pulsar radio emission, we are uncertain whether they are intrinsic to the source, due to the influence of observation sampling on the periodicity analysis performed. Remarkably, we find evidence to suggest that the pulsar may undergo pre-ignition periods of 'emission flickering', that is rapid changes between radio-on (active) and -off (null) emission states, before transitioning to a steady radio-emitting phase. We find no direct evidence to indicate that the object exhibits any change in spin-down rate between its radio-on and -off emission modes. We do, however, place an upper limit on this variation to be <= 6 % from simulations. This indicates that emission cessation in pulsars does not necessarily lead to large changes in spin-down rate. Moreover, we show that such changes in spin-down rate will not be discernible in the majority of objects which exhibit short-term (<= 1 d) emission cessation. In light of this, we predict that many pulsars could exhibit similar magnetospheric and emission properties to PSR B0823+26, but which have not yet been observed.