A catalog of X-ray point sources from two megaseconds of Chandra observations of the Galactic center

M. P. Muno, F. E. Bauer, F. K. Baganoff, R. M. Bandyopadhyay, G. C. Bower, W. N. Brandt, P. S. Broos, A. Cotera, S. S. Eikenberry, G. P. Garmire, S. D. Hyman, N. E. Kassim, C. C. Lang, T. J.W. Lazio, C. Law, J. C. Mauerhan, M. R. Morris, T. Nagata, S. Nishiyama, S. ParkS. V. Ramìrez, S. R. Stolovy, R. Wijnands, Q. D. Wang, Z. Wang, F. Yusef-Zadeh

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122 Scopus citations

Abstract

We present a catalog of 9017 X-ray sources identified in Chandra observations of a 2°x 0°.8 field around the Galactic center. This enlarges the number of known X-ray sources in the region by a factor of 2.5. The catalog incorporates all of the ACIS-I observations as of 2007 August, which total 2.25 Ms of exposure. At the distance to the Galactic center (8 kpc), we are sensitive to sources with luminosities of 4 x 1032 erg s -1 (0.5-8.0 keV; 90% confidence) over an area of 1 deg2, and up to an order of magnitude more sensitive in the deepest exposure (1.0 Ms) around Sgr A*. The positions of 60% of our sources are accurate to < 1 " (95% confidence), and 20% have positions accurate to < 0".5. We search for variable sources, and find that 3% exhibit flux variations within an observation, and 10% exhibit variations from observation-to-observation. We also find one source, CXOUGC J174622.7-285218, with a periodic 1745 s signal (1.4% chance probability), which is probably a magnetically accreting cataclysmic variable. We compare the spatial distribution of X-ray sources to a model for the stellar distribution, and find 2.8σ evidence for excesses in the numbers of X-ray sources in the region of recent star formation encompassed by the Arches, Quintuplet, and Galactic center star clusters. These excess sources are also seen in the luminosity distribution of the X-ray sources, which is flatter near the Arches and Quintuplet than elsewhere in the field. These excess point sources, along with a similar longitudinal asymmetry in the distribution of diffuse iron emission that has been reported by other authors, probably have their origin in the young stars that are prominent at l ∼ 0°.1.

Original languageEnglish (US)
Pages (from-to)110-128
Number of pages19
JournalAstrophysical Journal, Supplement Series
Volume181
Issue number1
DOIs
StatePublished - Sep 8 2009

Keywords

  • Galaxy: center
  • X-rays: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Muno, M. P., Bauer, F. E., Baganoff, F. K., Bandyopadhyay, R. M., Bower, G. C., Brandt, W. N., Broos, P. S., Cotera, A., Eikenberry, S. S., Garmire, G. P., Hyman, S. D., Kassim, N. E., Lang, C. C., Lazio, T. J. W., Law, C., Mauerhan, J. C., Morris, M. R., Nagata, T., Nishiyama, S., ... Yusef-Zadeh, F. (2009). A catalog of X-ray point sources from two megaseconds of Chandra observations of the Galactic center. Astrophysical Journal, Supplement Series, 181(1), 110-128. https://doi.org/10.1088/0067-0049/181/1/110