Faint X-Ray Sources in the Globular Cluster Terzan 5

We report our analysis of a Chandra X-ray observation of the rich globular cluster Terzan 5, in which we detect 50 sources to a limiting 1.0-6 keV X-ray luminosity of 3 × 10³¹ ergs s^-1 within the half-mass radius of the cluster. Thirty-three of these have L_X > 10³² ergs s^-1, the largest number yet seen in any globular cluster. In addition to the quiescent low-mass X-ray binary (LMXB; identified by Wijnands et al.), another 12 relatively soft sources may be quiescent LMXBs. We compare the X-ray colors of the harder sources in Terzan 5 to the Galactic center sources studied by Muno and collaborators and find the Galactic center sources to have harder X-ray colors, indicating a possible difference in the populations. We cannot clearly identify a metallicity dependence in the production of low-luminosity X-ray binaries in Galactic globular clusters, but a metallicity dependence of the form suggested by Jordán et al. for extragalactic LMXBs is consistent with our data.