... Titarchuk Lev, Seifina Elena, Frontera Filippova "Spectral state evolution of 4U 1820-30: the stability of the spectral index of the Comptonization tail", 2013, Astrophysical J., 767, 160 PDF . ...
... Note, X-ray nonthermal power-law tails are also observed in soft states of BHs (see, for example, a review by ST09; see also McConnell et al. 2002 and Wardzi'nski et al. 2002 on the detection of the extended hard tails in the hard states of BHs, Cyg X-1 ...
... in order to explain the high-energy tail observed in HSS of BH sources, one should ... difficulties given that the hard power-law tails of these spectra are too steep to ...
... in the accretion disk, along with a steep power-law tail whose photon index ( = 23) monotonically increases with the mass ... by a specific " "-shaped track in a colorcolor diagram. a harder power-law tail (the photon index of which is around 1.7 ...
... et al. (2001) successfully described this emission feature with the Gaussian line model and used a model consisting of a thermal component (dominating energy release around 1 keV) and a thermal Comptonization tail to describe the 0.150 keV continuum ...