A model on transition between steady states of sub-Keplerian accretion discs: implication for spectral states and hot corona above the disc

Abstract

We present here a simple hydrodynamic model based on a sequence of steady states of the inner sub-Keplerian accretion disc to understand its different spectral states. Correlations between different hydrodynamic steady states are studied with a goal to understand the origin of, e.g., the aperiodic variabilities. The plausible source of corona/outflow close to the central compact object is shown to be a consequence of steady state transition in the underlying accretion flow. We envisage that this phenomenological model can give insight on the influence of viscosity, efficiency of energy advection, nature of the background flow and environment on the evolution of the inner sub-Keplerian accretion disc.