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[25.04] The Relation Between Low Mass X-Ray Binaries and Globular Clusters: Chandra and HST Observations of M87

A. Jordan (Rutgers University), ACS Virgo Cluster Survey Team

The ACIS instrument on board Chandra has been used to carry out the first study of low mass X-ray binaries (LMXBs) in M87, the giant elliptical galaxy near the dynamical center of the Virgo Cluster. The LMXB catalog is combined with a globular cluster catalog obtained from F475W and F850LP images taken with ACS on HST as part of the Virgo Cluster Survey. In agreement with previous findings for other galaxies we find the efficiency of LMXB formation in globular clusters to scale with cluster metallicity, Z, and luminosity, in the sense that brighter, more metal-rich clusters are more likely to contain LMXBs. For the first time, however, we are able to demonstrate that the probability, p_X, that a given cluster will contain a LMXB depends sensitively on the dynamic properties of the host cluster by using the HST images to measure half-light radii, concentration indices and central densities for each globular. We obtain an explicit form for p_X and argue that the observed metallicity dependence is a consequence of an increased number of high mass stars forming in metal-rich environments. Finally, we find no compelling evidence for a break in the luminosity distribution of resolved X-ray point sources.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.