Pulsar Single Pulse Intensity Measurements and Pulse Nulling

Abstract

The intensity fluctuations of individual pulses from 32 pulsars have been examined. Previous studies have shown that the emission from some pulsars occasionally decreases dramatically for a few periods before returning to normal. This effect is known as pulse nulling. An estimate is made of the fraction of time spent by each of the observed pulsars in the nulled state, and it is found that pulse nulling is a characteristic of pulsar old age. There is no evidence for any pulsar emission during a null. An autocorrelation analysis performed on the data indicates that the radiation from pulsars is generated in bursts of typically 50 pulses. It is suggested that pulse nulls correspond to the time intervals between these bursts and that the bursts occur less frequently as a pulsar grows older. A pulsar will then effectively die when the separation of the bursts becomes much larger than their duration.