EDP Sciences
Free access
Volume 480, Number 3, March IV 2008
Page(s) 807 - 810
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20079027
Published online 25 January 2008

A&A 480, 807-810 (2008)
DOI: 10.1051/0004-6361:20079027

XMMU J134736.6+173403: an eclipsing LMXB in quiescence or a peculiar AGN?

S. Carpano1, B. Altieri2, A. R. King3, A. Nucita1, and P. Leisy4

1  XMM-Newton Science Operations Centre, ESAC, ESA, PO Box 50727, 28080 Madrid, Spain
    e-mail: scarpano@sciops.esa.int
2  Herschel Science Centre, ESAC, ESA, PO Box 50727, 28080 Madrid, Spain
3  Department of Physics and Astronomy, University of Leicester, Leicester LE1 7 RH, UK
4  Isaac Newton Group of Telescopes, Apartado de Correos 321, 38700 Sta. Cruz de La Palma, Spain; Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain

(Received 8 November 2007 / Accepted 8 January 2008)

Aims.We report the discovery of a peculiar object observed serendipitously with XMM-Newton. We present its timing and spectral properties and investigate its optical counterpart.
Methods.The light curve of the X-ray source, its spectrum, and the spectrum of the best optical counterpart are presented and analyzed.
Results.The X-ray flux decreases by a factor of 6.5 within 1 h and stays in a low state for at least 10 h, thereby suggesting the presence of an eclipse. The spectrum is very soft, a power law with a slope of $\Gamma\sim2.8$, and does not change significantly before and after the flux drop. The source is spatially coincident within few arc-seconds with a Seyfert 2 galaxy belonging to a galaxy pair.
Conclusions.Although the background AGN seems the best counterpart, neither the temporal nor the spectral properties of the X-ray source are compatible with it. We investigate the possibility of having a foreground low-mass X-ray binary in quiescence, where the companion is not detected in the optical wavelength.

Key words: X-rays: general -- X-rays: binaries -- galaxies: Seyfert

© ESO 2008