0740026

Even though the spectrum of canonical hard state of Galactic black hole transients (GBHT) is often described by a power law with a cut-off analysis of the RXTE and the INTEGRAL data show that this description may not be entirely correct. Some sources show a break in the power-law spectrum during the transition to the hard state but once a compact jet forms the break disappears at the HEXTE band (15 -- 200 keV). Therefore the shape of the hard X-ray spectrum in the low hard state is still one of the most important open questions of the black hole science. The disappearance of cut-offs may point out yet another relation between the jets and high energy emission. We propose one TOO observation of a GBHT with INTEGRAL at the hard state after the jet turns on (determined by radio or optical/infrared OIR observations) to search for breaks beyond 200 keV. By characterizing the gamma-ray domain at the hard state we will constrain the X- and gamma-ray emission mechanisms and also investigate the relation between the X-ray emission and jet formation. We will achieve multiwavelength coverage using ATCA in radio and SMARTS in optical/infrared. The current archival data are not enough to carry out this research. We request a single observation of 300 ks for one source. [truncated! Please see actual data for full text]