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arXiv · astro-ph/0312259

Two spectral states of the transient X-ray burster SAX J1747.0-2853

L. Natalucci·A. Bazzano·M. Cocchi·P. Ubertini·R. Cornelisse·J. Heise·J. J. M. in 't Zand
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Abstract

The neutron star binary SAX J1747.0-2853, located in the Galactic Center region at about 0.5 deg from Sgr A* and at a distance of 9 kpc, has been observed in outburst four times (1998, 1999, 2000 and 2001) by BeppoSAX and RossiXTE. At the time of its discovery in 1998 the source was observed in a low/hard state, showing a hard tail with a high energy cutoff of 70 keV. About two years later the source reappeared about one order of magnitude brighter in the X-rays (0.5-10 keV) and with a significantly steeper spectrum. As was the case for the low state, the data could be fitted by an input model based on two continuum primary components: a) a soft thermal excess, which is ~4 times more luminous than the one found in hard state; b) a non-thermal component which is compatible with either a power-law or a comptonization spectrum. The soft component is equally well described by pure blackbody or multi-color disk emission, with significantly higher temperature than observed in low state (~1.3 vs. the ~0.5 keV assuming pure blackbody). For this model, the flux of the non-thermal component below ~10 keV is a significant fraction of the total X-ray flux, i.e. greater than ~50% in the 2-10 keV band.

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L. Natalucci, A. Bazzano, M. Cocchi, P. Ubertini, R. Cornelisse, J. Heise, J. J. M. in 't Zand. 2003-12-10. Two spectral states of the transient X-ray burster SAX J1747.0-2853. https://doi.org/10.1051/0004-6361%3A20035680

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