Unveiling the nature of the highly absorbed X-ray source SAX J1748.2-2808 with XMM-Newton

We report on the results of an EPIC XMM-Newton observation of the faint source SAX J1748.2-2808 and the surrounding field. This source was discovered during the BeppoSAX Galactic center survey performed in 1997–1998. A spatial analysis resulted in the detection of 31 sources within the EPIC field of view. SAX J1748.2-2808 is clearly resolved into 2 sources in EPIC images with the brighter contributing almost 80% of the 2–10 keV flux. Spectral fits to this main source are consistent with an absorbed power-law with a photon index of $1.4\pm 0.5$ and absorption equivalent to $14 ^{+6} _{-4}\times 10^{22}$ cm-2 together with an iron line at $6.6 ^{+0.2} _{-0.2}$ keV with an equivalent width of $780 ^{+620}_{-380}$ eV. The significantly better statistics of the XMM-Newton observation, compared with BeppoSAX, allows to exclude a thermal nature for the X-ray emission. A comparison with other observations of SAXJ1748.2-2808 does not reveal any evidence for spectral or intensity long-term variability. Based on these properties we propose that the source is a low-luminosity high-mass X-ray binary located in the Galactic center region