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J.E. Grindlay, C.O. Heinke, P.D. Edmonds, S.S. Murray (CfA), F. Camilo (Columbia Univ.)
With Chandra, we obtained a deep (74ksec) ACIS-I observation of the well-studied globular cluster 47Tuc in March, 2000. The image is quite spectacular, with over 100 sources detected within a 1.5 arcmin (radius) region of the cluster center (i.e. within ~4 core radii), as reported by Grindlay et al (2000). This may be the most crowded field imaged by Chandra and is a testimony to the superb resolution and performance. Here we provide additional details of this first truly ``x-ray globular" cluster: the x-ray hardness ratios and/or spectra, long-term variability and searches for pulsations (>10sec) of the brighter sources. Sources are grouped into possible x-ray spectral types, and the luminosity and spatial distributions examined for each. A significant fraction (nearly 1/3) of the total Chandra source population may be already optically identified in our ongoing studies of deep HST images (see companion paper by Edmonds et al), and thus x-ray vs. optical classification is possible. We also report analysis of the x-ray properties vs. radio properties of the significant population of millisecond pulsars (MSPs) detected: 12 of the 15 MSPs in 47Tuc with precise positions (Camilo et al 2000) are detected by Chandra. With the precise x-ray (Chandra) vs. radio (Parkes) astrometry enabled by the MSPs, and the Chandra vs. HST astrometry enabled by identifications of other cluster sources with optical variables and CVs, we have conducted a search for MSP optical counterparts and optical variability at the known MSP binary periods. This rich dataset will test models for the formation and evolution of compact binaries and compact objects (particularly neutron stars vs. massive white dwarfs) in dense cluster cores. This work is supported in part by NASA.