Continuum Observations of Recycled Pulsars

Abstract

Continuum observations are used to investigate the nature of the eclipse of PSR 1957+20 and the distribution of pulsars in globular clusters. The frequency dependence of continuum and pulsed ellipse are found to differ dramatically. While a substantial loss of continuum power occurs during pulsed eclipse at an observing frequency of 90 cm, the continuum flux density of PSR 1957+20 is largely undiminished at 20 cm, with the possible exception of a short asymmetric ellipse. This observation severely limits the density of the companion’s wind and implies that the 20 cm pulsed eclipse is largely due to the loss of coherent pulsations. Continuum studies are also shown to be useful for examining the pulsar population of globular clusters. From observations of a sample of clusters it is found that the number of pulsars in a cluster scales approximately as the square root of the stellar collision rate. Deep continuum observations of the rich globular cluster Terzan 5 reveal steep spectrum sources distributed throughout the cluster core, implying the presence of a large population of pulsars.