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The geometry of the accretion flow in black-hole X-ray binaries in the hardstate, in particular the position of the disc inner edge, has been a subject ofintense debate in recent years. We address this issue by performing a spectralstudy of simultaneous observations of Cyg X-1 in the hard state by NuSTAR andSuzaku. The same data were analysed before, and modelled by a lamppostcontaining hybrid electrons and located very close to the horizon, whichemission was incident on a surrounding disc extending almost to the innermoststable circular orbit. We re-analyse the incident continuum model and show thatit suffers from the lack of physical self-consistency. Still, the good fit tothe data provided by this model indicates that the real continuum has a similarshape. We find it features a strong soft X-ray excess below a few keV, which wemodel as a soft thermal-Comptonization component, in addition to the main hardthermal-Compton component. This continuum model with reflection of bothcomponents yields the overall lowest $\chi^2$ and has a geometry with a hotinner accretion flow and a disc truncated at $\simeq$13--20 gravitationalradii. On the other hand, we have also found spectral solution with a lamppostat a large height and a disc that can extend to the innnermost stable circularorbit, though somewhat statistically worse. Overall, we find the fittedtruncation radius depends on the assumed continuum and geometry.

Analysis of NuSTAR and Suzaku observations of Cyg X-1 in the hard state: evidence for a truncated disc geometry