The X-ray spectrum of the black hole candidate Swift J1753.5−0127

We present a spectral analysis of the black hole candidate and X-ray transient source Swift J1753.5−0127 making use of simultaneous observations of XMM-Newton and Rossi X-ray Timing Explorer in 2006, when the source was in outburst. The aim of this paper is to test whether a thermal component due to the accretion disc is present in the X-ray spectrum. We fit the data with a range of spectral models, and we find that for all of these models, the fits to the X-ray energy spectra significantly require the addition of the disc blackbody component. We also find a broad iron emission line at around 6.5 keV, most likely due to iron in the accretion disc. Our results confirm the existence of a cool inner disc extending near or close to the innermost circular orbit. We further discovered broad emission lines of N vii and O viii at ∼0.52 and 0.65 keV, respectively, in the RGS spectrum of Swift J1753.5−0127.