We obtained steady solutions of magnetized black hole accretion disks taking into the azimuthal mean magnetic fields. We present the results for (1) a single-temperature disk and (2) optically thin, two-temperature disks. In the single-temperature model, we took into account the gas pressure, magnetic pressure, and radiation pressure, and assumed the bremsstrahlung cooling in the optically thin limit and the black body cooling in the optically thick limit. On the other hand, in the optically thin, two-temperature model, we assumed the bremsstrahlung cooling, synchrotron cooing, and inverse-Compton effects. Based on the results of 3D MHD and Radiation-MHD simulations of accretion disks, we assumed that magnetic fields inside the disk are turbulent and dominated by the azimuthal component, and that the azimuthally averaged Maxwell stress is proportional to the total pressure. We found that when accretion rate exceeds the threshold for the onset of the thermal instability in opt
ically thin disks, a magnetic pressure dominated, cool branch (we call "low-beta branch") appears in the thermal equilibrium curve. The low-beta branch extends to an optically thick regime. This disk may correspond to the "Bright/Hard" state in black hole candidates observed during the transition from a Low/Hard state to a High/Soft state. We also obtained transonic global solutions and the spectrum for optically thin, two-temperature disks. We found that when the mass accretion rate is high, the bremsstrahlung-Compton effect is dominant as the cooling mechanism inside the disk. |