Radiation hydrodynamics simulations of wide-angle outflows from super-critical accretion disks around black holes

TL;DR

This study uses radiation hydrodynamics simulations to explore wide-angle outflows from super-critical black hole accretion disks, revealing their structure, velocity, and energetic properties, and linking them to observed ultra-luminous X-ray sources.

Contribution

The paper presents the first detailed 2D radiation hydrodynamics simulations of wide-angle outflows from super-critical accretion disks around black holes, demonstrating their properties and observational relevance.

Findings

Outflows are launched via radiation force and have wide angular extent.

Mass outflow rate exceeds the accretion rate onto the black hole.

Kinetic power of outflows is comparable to or exceeds the photon luminosity.

Abstract

By performing two-dimensional radiation hydrodynamics simulations with large computational domain of 5000 Schwarzschild radius, we revealed that wide-angle outflow is launched via the radiation force from the super-critical accretion flows around black holes. The angular size of the outflow, of which the radial velocity (v_r) is over the escape velocity (v_esc), increases with an increase of the distance from the black hole. As a result, the mass is blown away with speed of v_r > v_esc in all direction except for the very vicinity of the equatorial plane, theta=0-85^circ, where theta is the polar angle. The mass ejected from the outer boundary per unit time by the outflow is larger than the mass accretion rate onto the black hole, ~150L_Edd/c^2, where L_Edd and c are the Eddington luminosity and the speed of light. Kinetic power of such wide-angle high-velocity outflow is comparable to the photon luminosity and is a few times larger than the Eddington luminosity. This corresponds to ~10^39-10^40 erg/s for the stellar mass black holes. Our model consistent with the observations of shock excited bubbles observed in some ultra-luminous X-ray sources (ULXs), supporting a hypothesis that ULXs are powered by the super-critical accretion onto stellar mass black holes.