Volume 430, Number 1, January IV 2005
|Page(s)||L9 - L12|
|Published online||12 January 2005|
Letter to the Editor
Discovery of a bright X-ray transient in the Galactic Center with XMM-Newton
Max-Planck-Institut für extraterrestrische Physik, PO Box 1312, Garching bei München 85741, Germany e-mail: firstname.lastname@example.org
2 Laboratoire d'Astrophysique de Grenoble, Université Joseph-Fourier, BP 53, 38041 Grenoble Cedex 9, France
3 Department of Astronomy, Odessa National University, T. G. Shevchenko park, 65014 Odessa, Ukraine
4 Crimean Astrophysical Observatory, 98409 Nauchny, Ukraine
5 Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
Accepted: 2 December 2004
We report the discovery of a bright X-ray transient object, XMMU J174554.4–285456, observed in outburst with XMM-Newton on October 3, 2002, and located at 6.3′ from Sgr A*, the supermassive black hole at the Galactic center. This object exhibits a very large X-ray luminosity variability of a factor of about 1300 between two X-ray observations separated by four months. The X-ray spectrum is best fitted by a power-law with a photon index of and absorption column density of cm-2. This large absorption suggests this source is located at the distance of the Galactic center, i.e., 8 kpc. The 2–10 keV luminosity is about erg s-1. A pulsation period of about 172 s is hinted by the timing analysis. The X-ray properties strongly suggest a binary system with either a black hole or a neutron star for the compact object.
Key words: Galaxy: center / X-rays: binaries / X-rays: individuals: XMMU J174554.4–285456
© ESO, 2005
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