The X-ray spectrum from a cool accretion disk heated by virialized protons is computed .
The cool disk is either embedded in a magnetically heated accretion disk corona or partly extends into an ion supported torus ( or ADAF ) .
We calculate the stationary equilibrium between proton heating , electron thermal conduction and the radiative losses by bremsstrahlung and Compton scattering .
A heated surface layer on top of the accretion disk is produced with temperatures between 60–90 keV above a cool layer with temperatures of 0.01 keV ( AGN ) and 1keV ( galactic black hole candidates ) .
The spectra produced by the surface layer are reminiscent of hard state spectra , but a bit too steep , especially for AGN ’ s .
Near the inner edge of the disk , where the optical depth of the disk \tau \lesssim 1 , we find that the cool component of the disk disappears .
Instead , the hot protons from the corona/ADAF heat the disk , on a dynamical time-scale , to temperatures of several 100 keV , limited by pair production .
This region , here called a ‘ warm disk ’ , could contribute significantly to the hard X-ray spectra and could be important for feeding material into an ADAF .