Chandra Observations of the Faintest Low-Mass X-Ray Binaries

Colleen. A. Wilson, Sandeep K. Patel, Chryssa Kouveliotou, Peter G. Jonker, Michiel van der Klis, Walter H. G. Lewin, Tomaso Belloni, Mariano Méndez

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A group of persistently faint Galactic X-ray sources exist that, based on their location in the Galaxy, high LX/Lopt, association with X-ray bursts, and absence of low-frequency X-ray pulsations, are thought to be low-mass X-ray binaries (LMXBs). We present results from Chandra observations for eight of these systems: 4U 1708-408, 2S 1711-339, KS 1739-304, SLX 1735-269, GRS 1736-297, SLX 1746-331, 1E 1746.7-3224, and 4U 1812-12. Locations for all these sources, excluding GRS 1736-297, SLX 1746-331, and KS 1739-304 (which were not detected), were improved to 0.6" error circles (90% confidence). Our observations support earlier findings of transient behavior of GRS 1736-297, KS 1739-304, SLX 1746-331, and 2S 1711-339 (which we detect in one of two observations). Energy spectra for 4U 1708-408, 2S 1711-339, SLX 1735-269, 1E 1746.7-3224, and 4U 1812-12 are hard, with power-law indices typically 1.4-2.1, which is consistent with typical faint LMXB spectra.
Original languageEnglish
Pages (from-to)1220-1228
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 1-Oct-2003


  • Accretion
  • Accretion Disks
  • Stars: Binaries: Close
  • X-Rays: Binaries
  • X-Rays: Stars

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