  The emission from galactic black holes and Seyfert galaxies is generally
understood in term of two-phase models (Haardt and Maraschi 1991, 1993). Such
models postulate that a hot plasma coexists with relatively colder material in
the inner part of the accretion flow. We present the first simulated broad-band
spectra produced by such a system and accounting simultaneously for energy
balance and Comptonisation in the hot phase, together with reflection,
reprocessing, ionization and thermal balance in the cold phase. This was made
possible by coupling three radiative transfer codes: a non-linear Monte-Carlo
code (NLMC), a photo-ionization code TITAN and a linear Monte-Carlo code NOAR.
The equilibrium comptonisation spectrum appears to be sensitive to the shape of
the reprocessed spectrum that, in turn, depends on the ionization parameter,
but also on the structure of the irradiated cold material. This is illustrated
by a comparison of simulations assuming constant density or a constant pressure
in the cold phase. We also compare our results with simplified models where
reprocessing is approximated by a blackbody spectrum. Our detailed treatment
leads to noticeably different spectral energy distributions (SEDs)
characterised by harder X-ray spectra. Even at low ionization parameters the
commonly used blackbody approximation is poor, leading to X-ray spectra that
are too soft. The effect, however, seems not to be strong enough to reconcile
the slab corona model with the hardest observed spectra, unless the reflector
has a constant density and the ionization parameter is large.
