Simultaneous X-ray and 7-ray observations of Cyg X-1 in the hard state by Ginga and OSSE

摘要: We present four X-ray/gamma-ray spectra of Cyg X-1 observed in the hard ('low') state simultaneously by Ginga and GRO/OSSE on 1991 July 6. The 3-30 keV are well represented power laws with an energy spectral index alpha~0.6 a Compton reflection component including fluorescent Fe K-alpha corresponding to solid angle reflector ~0.3 times 2 Pi. overall Ginga/OSSE can be modelled repeated scattering mildly-relativistic, tau ~1, plasma. However, high-energy cutoff is steeper than that due single-temperature thermal Comptonisation. It described superposition dominant optically-thin, emission at kT~140 Wien-like from optically-thick plasma kT~50 keV. X-ray do not show presence anisotropy break required if takes place corona above cold disc. Also, flat shows soft-photon starved, i.e., luminosity incident soft seed photons very much less X-rays. Furthermore, significantly pi. These facts taken together strongly rule out disc-corona geometry. Rather, consistent geometry which accretion disc (which both supplies X-rays reflects X-rays) only exists large radii, while Comptonising hot located inner region no This consists either pure electron-positron pairs source size ~5 Schwarzschild radii or it contains also protons larger.