ACCEPTED BY THE Astrophysical Journal Preprint typeset using L ATEX style emulateapj v. 14/09/00 CHANDRA OBSERVATION OF THE GLOBULAR CLUSTER NGC 6440 AND THE NATURE OF CLUSTER X-RAY LUMINOSITY FUNCTIONS

As part of our campaign to determine the nature of the various source populations of the low-luminosity globular cluster X-ray sources, we have obtained a Chandra X-Ray Observatory ACIS-S3 image of the globular cluster NGC 6440. We detect 24 sources to a limiting luminosity of ~2 × 1031 ergs s-1 (0.5-2.5 keV) inside the cluster's half-mass radius, all of which lie within ~2 core radii of the cluster center. We also find excess emission in and around the core that could be due to unresolved point sources. Based on X-ray luminosities and colors, we conclude that there are 4-5 likely quiescent low-mass X-ray binaries and that most of the other sources are cataclysmic variables. We compare these results to Chandra results from other globular clusters and find the X-ray luminosity functions differ among the clusters.

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