X-ray sources with periodic variability in a deep Chandra image of the Galactic center

M. P. Muno, F. K. Baganoff, M. W. Bautz, W. N. Brandt, G. P. Garmire, G. R. Ricker

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20 Scopus citations

Abstract

We report the discovery of eight X-ray sources with periodic variability in 487 ks of observations of the Galactic center with Chandra. The sources are identified from a sample of 285 objects detected with 100-4200 net counts. Their periods range from 300 s to 4.5 hr, with amplitudes between 40% and 70% rms. They have luminosities of (1-5) × 1032 ergs s -1 (2-8 keV at 8 kpc). The spectra of seven of the eight sources are consistent with τ ≈ 0 power laws absorbed by gas and dust with a column density equal to or higher than that toward the Galactic center (6 × 1022 cm-2). Four of these sources also exhibit emission lines near 6.7 keV from He-like Fe, with equivalent widths of 600-1000 eV. These properties are consistent with both magnetically accreting cataclysmic variables and wind-accreting neutron stars in high-mass X-ray binaries. The eighth source has an absorbing column of 5 × 1021 cm -2 that places it in the foreground. Its spectrum is consistent with either a τ = 1.4 power law or kT = 25 keV bremsstrahlung emission. Its period-folded flux profile clearly identifies it as an eclipsing polar. We place an approximate upper limit of i′ > 23 mag on the optical counterpart to this source using a 5 minute exposure obtained with the Magellan Instant Camera on the Clay telescope (Magellan II) at Las Campanas.

Original languageEnglish (US)
Pages (from-to)465-474
Number of pages10
JournalAstrophysical Journal
Volume599
Issue number1 I
DOIs
StatePublished - Dec 10 2003

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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