Volume 416, Number 2, March III 2004
|Page(s)||699 - 702|
|Section||Stellar structure and evolution|
|Published online||27 February 2004|
Two spectral states of the transient X-ray burster SAX J1747.0–2853
CNR-Istituto di Astrofisica Spaziale e Fisica Cosmica, Area Ricerca Roma 2/Tor Vergata, via del Fosso del Cavaliere 100, 00133 Roma, Italy
2 SRON National Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
3 Astronomical Institute, Utrecht University, PO Box 80000, 3508 TA Utrecht, The Netherlands
4 Dept. of Physics and Astronomy, University of Southampton, Hampshire SO17 1BJ, UK
Corresponding author: L. Natalucci, email@example.com
Accepted: 4 December 2003
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.
Key words: stars: binaries: close / stars: individual: SAX J1747.0–2853 / X-rays: bursts
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.