Volume 407, Number 1, August III 2003
|Page(s)||L17 - L20|
|Published online||17 November 2003|
Letter to the Editor
XMM-Newton observation of the brightest X-ray flare detected so far from Sgr A*
Max-Planck-Institut für extraterrestrische Physik, PO Box 1312, Garching bei München 85741, Germany
2 Laboratoire d'Astrophysique de Grenoble, Université Joseph-Fourier, BP 53, 38041 Grenoble Cedex 9, France
3 CEA, DSM, DAPNIA, Service d'Astrophysique, C.E. Saclay, 91191 Gif-Sur-Yvette Cedex, France
4 Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
Corresponding author: D. Porquet, firstname.lastname@example.org
Accepted: 26 June 2003
We report the high S/N observation on October 3, 2002 with XMM-Newton of the brightest X-ray flare detected so far from Sgr A* with a duration shorter than one hour (~2.7 ks). The light curve is almost symmetrical with respect to the peak flare, and no significant difference between the soft and hard X-ray range is detected. The overall flare spectrum is well represented by an absorbed power-law with a soft photon spectral index of , and a peak 2–10 keV luminosity of 3.6 erg s-1, i.e. a factor 160 higher than the Sgr A* quiescent value. No significant spectral change during the flare is observed. This X-ray flare is very different from other bright flares reported so far: it is much brighter and softer. The present accurate determination of the flare characteristics challenge the current interpretation of the physical processes occuring inside the very close environment of Sgr A* by bringing very strong constraints for the theoretical flare models.
Key words: Galaxy: center / X-rays: individuals: Sgr A* / X-rays: general / radiation mechanisms: general
© ESO, 2003
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