The nature of the low-luminosity globular cluster X-ray sources.

An X-ray survey of 134 galactic globular clusters was performed with the Large-Area Sky Survey Experiment aboard HEAO 1. No new globular cluster X-ray sources were discovered, confirming the gap in the luminosity function discussed, obtaining upper limits on X-ray emission from 67 globular clusters. Statistical analyses reveal that the presence of both high-luminosity and low-luminosity globular cluster X-ray sources is correlated with the time scale for binary formation via the tidal capture mechanism within globular clusters. Among other predictions, a turnover in the luminosity function below 10 to the 32nd erg/s is expected. Finally, the implications of the model presented on the evolution of globular cluster X-ray sources and on low-mass X-ray binaries and cataclysmic variables in the galactic plane.