Gamma-ray emission from millisecond pulsars in globular clusters

Abstract

RECENT observations indicate that a typical globular cluster may contain hundreds of millisecond pulsars^1,2. Because millisecond pulsars have some similarities to the Vela pulsar, which is known to be a source of γ-rays, they could also be gamma emitters of modest power. Here I estimate the γ-ray luminosity of globular clusters, assuming that they indeed harbour large numbers of millisecond pulsars. An upper limit obtained by the Cos-B satellite on the γ-ray emission from 47 Tucanae, which contains at least 10 millisecond pulsars¹, is too large to constrain the model presented here, but the estimated luminosities are high enough to be detectable by the recently launched Gamma Ray Observatory. In the near future, γ-ray observations will thus be able to test this model, and the theory of γ-ray emission by millisecond pulsars.