ON THE OBSERVABILITY OF MICROSECOND TEMPORAL STRUCTURE IN THE EMISSION FROM X-RAY BINARY PULSARS

We discuss the possibility of detecting the microsecond granularity expected in the flux from wind-fed X-ray binary pulsars. This microsecond structure is predicted by the noisy accretion scenario; we derive the physical characteristics of such burst structure in the framework of this model. We investigate the temporal dispersion induced by the scattering of burst photons in their passage through the neutron star magnetosphere and conclude that microsecond structure could indeed be observable for energies less than the cyclotron energy. We show that the coincidence timing mode for the Proportional Counter Array on-board XTE can be used very effectively to statistically discriminate these microsecond bursts from accidental spurious detections.