Numerical simulations of winds driven by radiation force from the corona above a thin disk

TL;DR

This study uses two-dimensional hydrodynamical simulations to explore winds driven by radiation force from a hot corona above a thin accretion disk near a black hole, revealing how disk luminosity influences outflow strength and velocity.

Contribution

It provides the first detailed analysis of wind properties from a 10^9 K corona in the innermost disk regions using hydrodynamical simulations, highlighting the role of disk luminosity.

Findings

Outflows are stronger with higher disk luminosity.

Supersonic outflows reach speeds up to 10^4 km/s.

Outflows can escape the black hole's gravity and impact galactic scales.

Abstract

Observations show that winds can be driven from the innermost region (inside a 50 Schwarschild radius) of a thin disk. It is interesting to study the winds launched from the innermost region. A hot corona above the black hole (BH) thin disk is irradiated by the disk. We perform two-dimensional hydrodynamical simulations to study the winds driven by radiation force from the corona in the innermost regions. The hard X-ray spectrum from active galactic nuclei (AGNs) suggests that the corona temperature is about $10^9$ K, so that we mainly analyze the properties of winds (or outflows) from the $10^9$ K corona. The disk luminosity plays an important role in driving the outflows. The more luminous the disk, the stronger the outflows. Mass outflow rate ($\dot{M}_{\rm out}$) at a 90 Schwarschild radius depends on disk luminosity, which can be described as $\dot{M}_{\rm out}\propto 10^{3.3 \Gamma}$ ($\Gamma$ is the ratio of the disk luminosity to the Eddington luminosity). In the case of high luminosity (e.g. $\Gamma=0.75$), the supersonic outflows with maximum speed $1.0 \times 10^4$ Km s$^{-1}$ are launched at $\sim17^{o}$ --$30^{o}$ and $\sim50^{o}$ --$80^{o}$ away from the pole axis. The Bernoulli parameter keeps increasing with the outward propagation of outflows. The radiation force keeps accelerating the outflows when outflows move outward. Therefore, we can expect the outflows to escape from the BH gravity and go to the galactic scale. The interaction between outflows and interstellar medium may be an important AGN feedback process.