  The phenomenology of accretion disc, coronnae and jets in X-ray binaries is
rather well established. However the structure of the accretion flow in the
various spectral states is still debated and the connection between the hot
flow and compact jet is far from being understood. Simbol-X should address
these two important questions in several ways. First, it will provide us with
the capability of producing high sensivity, broad band spectra and therefore
constrain simultaneously the shape and luminosity of all spectral components
(iron line, reflection bump, thermal disc and comptonised emission) which in
turn provides information on the geometry of the accretion flow. It will also
determine the exact contribution of jets to the X-ray band both in bright and
quiescent states. Finally it will shed new lights on the underlying mechanisms
triggering spectral state transitions by allowing us to follow in exquisite
details the rapid spectral evolution and its correlation with the radio jet
emission during those transitions.

Astrophysics