Hard X-ray spectra of black hole binaries in the low/hard state are well modeled by thermal Comptonization of soft seed photons by a corona-type region with kT \sim 50 keV and optical depth around 1 .
Previous spectral studies of 1E 1740.7 - 2942 , including both the soft and the hard X-ray bands , were always limited by gaps in the spectra or by a combination of observations with imaging and non-imaging instruments .
In this study , we have used three rare nearly-simultaneous observations of 1E 1740.7 - 1942 by both XMM-Newton and INTEGRAL satellites to combine spectra from four different imaging instruments with no data gaps , and we successfully applied the Comptonization scenario to explain the broadband X-ray spectra of this source in the low/hard state .
For two of the three observations , our analysis also shows that , models including Compton reflection can adequately fit the data , in agreement with previous reports .
We show that the observations can also be modeled by a more detailed Comptonization scheme .
Furthermore , we find the presence of an iron K-edge absorption feature in one occasion , which confirms what had been previously observed by Suzaku .
Our broadband analysis of this limited sample shows a rich spectral variability in 1E 1740.7 - 2942 at the low/hard state , and we address the possible causes of these variations .
More simultaneous soft/hard X-ray observations of this system and other black-hole binaries would be very helpful in constraining the Comptonization scenario and shedding more light on the physics of these systems .