Bimodal behavior of accretion disks: Theory and application to Cygnus X-1 transitions

摘要: We develop a theory of Newtonian accretion disks based on an explicit formulation viscous stresses arising from turbulent magnetic fields which are generated by Keplerian differential rotation plasmas. It is particularly pointed out that two physically distinct states exist in the middle part disk surrounding black hole; transition one state to other takes place when physical conditions accreting gas near outer boundary cross over critical separating states. Thermal stability those examined. also found within certain inner radius develops into single, high-temperature state, irrespective conditions; copious emission hard X-rays arises this domain. then apply results construct definite numerical model Cyg X-1 accounting for observed features its transitions, such as magnitudes and spectral distributions X-ray luminosity, times, variabilities. Possibility transient sources associated with holes predicted.