Radiatively-driven black-hole winds revisited

Abstract

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

arXiv comment12 pages, 15 figures, published in MNRAS, some typos in equation (10) of the published article have been corrected

References in corpus (20)

• Evidence for ultra-fast outflows in radio-quiet AGNs: I - detection and statistical incidence of Fe K-shell absorption lines
• A Catalog of Broad Absorption Line Quasars in Sloan Digital Sky Survey Data Release 5
• Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers
• Evidence for ultra-fast outflows in radio-quiet AGNs: II - detailed photo-ionization modeling of Fe K-shell absorption lines
• A strong redshift dependence of the broad absorption line quasar fraction
• Evidence for ultra-fast outflows in radio-quiet AGNs: III - location and energetics
• Ultra Fast Outflows: Galaxy-Scale Active Galactic Nucleus Feedback
• Effects of Fluid Composition on Spherical Flows around Black Holes
• Black Hole Winds II: Hyper-Eddington Winds and Feedback
• Winds from Neutron Stars and Strong Type I X--Ray Bursts
• Simulations of momentum feedback by black hole winds
• Relativistic Radiative Flow in a Luminous Disk
• Equations of General Relativistic Radiation Hydrodynamics from Tensor Formalism
• Radiatively driven relativistic jets with variable adiabatic index equation of state
• Bulk motion Comptonization in black-hole accretion flows
• Equations of general relativistic radiation hydrodynamics in Kerr space-time
• Spherical Relativistic Radiation Flows with Variable Eddington Factor
• General relativistic study of astrophysical jets with internal shocks
• On the Mathematical Character of the Relativistic Transfer Moment Equations
• On the presence of ultra-fast outflows in the WAX sample of Seyfert galaxies

Cited by in corpus (3)

• Magnetic white dwarfs in post-common-envelope binaries
• Supermassive black hole formation via collisions in black hole clusters
• Radiatively driven, time dependent bipolar outflows