2003/08/19 by M. P. Muno, M. P. Muno, F. K. Baganoff +10
Physics and Astronomy · #Amplitude #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Bremsstrahlung #Flux (metallurgy) #Galactic Center #Neutron star #Power law #Spectral line #Stars #Telescope #astro-ph
paper · pdf · doi:10.1086/379244
published as Astrophys.J.599:465-474,2003; Erratum-ibid.621:1117,2005 · 11 pages including 6 figures. Submitted to ApJ
arxiv created 2003/08/19 · openalex publication_date 2003/12/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
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) × 10 32 ergs s -1 (2-8 keV at 8 kpc). The spectra of seven of the eight sources are consistent with Γ ≈ 0 power laws absorbed by gas and dust with a column density equal to or higher than that toward the Galactic center (6 × 10 22 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 × 10 21 cm -2 that places it in the foreground. Its spectrum is consistent with either a Γ = 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.