Re-examining the XMM–Newton spectrum of the black hole candidate XTE J1652−453




The XMM–Newton spectrum of the black hole candidate XTE J1652−453 shows a broad and strong Fe Kα emission line, generally believed to originate from reflection of the inner accretion disc. These data have been analysed by Hiemstra et al. using a variety of phenomenological models. We re-examine the spectrum with a self-consistent relativistic reflection model. A narrow absorption line near 7.2 keV may be present, which if real is likely the Fe xxvi absorption line arising from highly ionized, rapidly outflowing disc wind. The blueshift of this feature corresponds to a velocity of about 11 100 km s−1, which is much larger than the typical values seen in stellar mass black holes. Given that we also find the source to have a low inclination (i ≲ 32°; close to face-on), we would therefore be seeing through the very base of outflow. This could be a possible explanation for the unusually high velocity. We use a reflection model combined with a relativistic convolution kernel which allows for both prograde and retrograde black hole spin, and treat the potential absorption feature with a physical model for a photoionized plasma. In this manner, assuming the disc is not truncated, we could only constrain the spin of the black hole in XTE J1652−453 to be less than ∼0.5 Jc/GM2 at the 90 per cent confidence limit.