AAS 201st Meeting, January, 2003
Session 31. The Galactic Center and Its Environs
Oral, Monday, January 6, 2003, 2:00-3:30pm, 6AB

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[31.06] Two Thousand X-ray Stars in the Central 20 pc of the Galaxy

M. P. Muno, F. K. Baganoff, M. W. Bautz (MIT CSR), E. D. Feigelson, W. N. Brandt (PSU), M. Morris (UCLA), G. P. Garmire (PSU), G. R. Ricker (MIT CSR), L. K. Townsely, P. S. Broos (PSU)

We present a catalog of 2287 point sources detected during 600 ks of Chandra observations of the 17 by 17 arcminute field around Sgr A*. This field encompasses a physical area of 40 by 40 parsec at 8 kpc. The completeness limit of the sample at the galactic center is 1031 erg s-1 (2--8 keV), while the detection limit is a order of magnitude lower. We estimate that fewer than 60 of the observed sources are background AGN. The surface density of X-ray sources falls off as 1/R away from Sgr A*, which is very similar to the distribution of stars observed in the infrared. The \log(N)-\log(L) distribution of the galactic center sources is extremely steep, such that point sources can account for all of the previously reported diffuse X-ray emission if it extends down to 1029 erg s-1 with the same slope. However, there are numerous filamentary structures in the field that also contribute to the total X-ray flux, which implies that the luminosity distribution between 2--8 keV must turn over below our completeness limit. The spectra of the majority of the galactic center sources are very hard, and are best described by a power law (E-\Gamma) with photon index \Gamma < 1. Such hard spectra are only seen from magnetically accreting white dwarfs (polars and intermediate polars) and neutron stars (pulsars). Several interesting individual sources are also present in the field, including three low-mass X-ray binaries in quiescence, and five sources that vary with periodicities between 90 minutes and 5.4 hours.

The author(s) of this abstract have provided an email address for comments about the abstract: muno@space.mit.edu

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.