The eclipsing bursting X-ray binary EXO 0748-676 revisited by XMM-Newton

Abstract

The bright eclipsing and bursting low-mass X-ray binary EXO 0748-676 has been observed at several occasions by XMM-Newton during the initial calibration and performance verification (CAL/PV) phase. We present here the results obtained from observations with the EPIC cameras. Apart from several type-I X-ray bursts, the source shows a high degree of variability with the presence of soft flares. The wide energy coverage and high sensitivity of XMM-Newton allows for the first time a detailed description of the spectral variability. The source is found to be the superposition of a central (~2 10^8 cm) Comptonized emission, most probably a corona surrounding the inner edge of an accretion disk, associated with a more extended (~3 10^10 cm) thermal halo at a typical temperature of ~0.6 keV with an indication of non-solar abundances. Most of the variations of the source can be accounted for by a variable absorption affecting only the central comptonized component and reaching up to NH ~1.3 10^23 cm^{-2}. The characteristics of the surrounding halo are found compatible with an irradiated atmosphere of an accretion disc which intercepts the central emission due to the system high inclination.

arXiv comment6 pages, 4 figures, accepted for publication in A&A Letters, XMM special issue

References in corpus (4)

• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• High-Resolution spectroscopy of the low-mass X-ray binary EXO 0748-67
• A variable 0.58--2.44 Hz quasi-periodic oscillation in the eclipsing and dipping low-mass X-ray binary EXO 0748-676
• A 695-Hz quasi-periodic oscillation in the low-mass X-ray binary EXO 0748-676

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• Multiwavelength Observations of EXO 0748--676 -- II. Emission Line Behavior
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• Optical spectroscopy of the quiescent counterpart to EXO 0748-676
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