Radiatively-driven black hole winds revisited

ABSTRACT We examine general relativistic radiatively-driven spherical winds, using the basic equations for radiation hydrodynamics under moment formalism. Moment are often closed, equilibrium diffusion approximation, which has an acausal problem, and furthermore, gives nodal-type critical points. Instead, we use non-equilibrium approximation with a closure relation of variable Eddington factor, f(τ, β), where τ is optical depth β flow speed normalized by light. then analyse properties in detail several parameters, found that there appear saddle-type points as well nodal type spiral one. The most suitable saddle one appears region close to black hole. also calculate transonic solutions typical show luminosity almost comparable luminosity, gas quickly accelerated vicinity hole, wind terminal speeds on order 0.1–0.3 c. These results hole winds can be applied e.g. ultra-fast outflows, supposed fast outflows from supermassive holes.