Abstract We carried out systematic spectral analysis for 10 black hole candidates (BHCs) in the low/hard states, using archival RXTE and Beppo-SAX data which cover a broad energy range of 2–250 keV. For in total 156 observations, the simple analytic model, a power law with an exponentiall cutoff modified with a smeared edge model, were adopted. Consequently, we found that the photon index was distributed over 1.2–1.8 and the cutoff energy was more than 40 keV.We also found that there is the different behaviour between the photon index/cutoff energy and the luminosity at lower ahd higher luminosities with its value of 2×1037 erg s-1. For example, a clear anti-correlation is found between the cutoff energy and the luminosity when its value is more than 2×1037 erg s-1. In addition, we performed the same analysis for 1 neutron star (NS) and 1 active galactic nuclei (AGN) for comparison. No clear differences between BHCs, NS and AGN were found, which might suggest that the accretion mechanisms in the low/hard states are independent of the mass of the central object.
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