The Discovery Outburst of the X-Ray Transient IGR J17497-2821 Observed withRXTEand ATCA

We report the results of a series of RXTE and ATCA observations of therecently-discovered X-ray transient IGR J17497-2821. Our 3-200 keV PCA+HEXTEspectral analysis shows very little variations over a period of ~10 days aroundthe maximum of the outburst. IGR J17497-2821 is found in a typical Low HardState (LHS) of X-ray binaries (XRB), well represented by an absorbedComptonized spectrum with an iron edge at about 7 keV. The high value of theabsorption (~4 e22 cm-2) suggests that the source is located at a largedistance, either close to the Galactic center or beyond. The timing analysisshows no particular features, while the shape of the power density spectra isalso typical of LHS of XRBs, with ~36% RMS variability. No radio counterpart isfound down to a limit of 0.21 mJy at 4.80 GHz and 8.64 GHz. Although theposition of IGR J17497-2821 in the radio to X-ray flux diagram is well belowthe correlation usually observed in the LHS of black holes, the comparison ofits X-ray properties with those of other sources leads us to suggest that it isa black hole candidate.Comment: 6 pages, 4 figures accepted for publication in the Astrophysical Journal Letter