HOT ACCRETION DISKS WITH PAIRS - EFFECTS OF MAGNETIC-FIELD AND THERMAL CYCLOSYNCHROTRON RADIATION

We show the effects of thermal cyclosynchrotron radiation and magnetic viscosity on the structure of hot, two-temperature accretion disks. M agnetic field, B, is assumed to be randomly oriented and the ratio of magnetic pressure to either gas pressure, alpha = P(mag)/P(gas), or th e sum of the gas and radiation pressures, alpha = P(mag)/(P(gas) + P(r ad)), is fixed. We find those effects do not change the qualitative pr operties of the disks, i.e., there are still two critical accretion ra tes related to production of e+/- pairs, M(cr)U and M(cr)L, that affec t the number of local and global disk solutions, as recently found by Bjornsson and Svensson for the case with B = 0. However, a critical va lue of the alpha-viscosity parameter above which those critical accret ion rates disappear becomes smaller than alpha(cr) = 1 found in the ca se of B = 0, for P(mag) = alpha(P(gas) + P(rad)). If P(mag) = alphaP(g as), on the other hand, alpha(cr) is still about unity. Moreover, when Comptonized cyclosynchrotron radiation dominates Comptonized bremsstr ahlung, radiation from the disk obeys a power law with the energy spec tral index of approximately 0.5, in a qualitative agreement with X-ray observations of AGNs and Galactic black hole candidates. We also exte nd the hot disk solutions for P(mag) = alpha(P(gas) + P(rad)) to the e ffectively optically thick region, where they merge with the standard cold disk solutions. We find that the mapping method by Bjornsson and Svensson gives a good-approximation to the disk structure in the hot r egion and show where it breaks in the transition region. Finally, we f ind a region in the disk parameter space with no solutions due to the inability of Coulomb heating to supply enough energy to electrons.