Numerical simulation of hot accretion flows (IV): effects of black hole spin and magnetic field strength on the wind and the comparison between wind and jet properties

TL;DR

This study uses advanced simulations to analyze how black hole spin and magnetic fields influence winds and jets from hot accretion flows, revealing wind's significant role in AGN feedback.

Contribution

It extends previous work by including rapidly spinning black holes and MAD states, providing new formulae for wind and jet properties.

Findings

Stronger spin and magnetic fields enhance winds and jets.

Jet momentum flux remains smaller than wind's even at high spin.

Wind may be more influential than jet in AGN feedback.

Abstract

This is the fourth paper of our series of works studying winds from hot accretion flows around black holes. In the first two papers, we have shown the existence of strong winds in hot accretion flows using hydrodynamical and magnetohydrodynamical (MHD) simulations. In the third paper, by using three dimensional general relativity MHD numerical simulation data of hot accretion flows and adopting a "virtual particle trajectory" data analysis approach, we have calculated the properties of wind, such as its mass flux and velocity. However, that paper focuses only on a non-spinning black hole and SANE (standard and normal accretion). In the present paper, we extend the third paper by including cases of a rapidly rotating black hole and MAD (magnetically arrested disk). We focus on investigating the effect of spin and magnetic field on the properties of wind and jet. It is found that a larger spin and stronger magnetic field usually enhance the wind and jet. The formulae describing the mass flux, poloidal velocity, and fluxes of momentum, kinetic energy, and total energy of wind and jet are presented. One interesting finding, among others, is that even in the case of very rapidly spinning black hole where the jet is supposed to be the strongest, the momentum flux of jet is smaller than that of wind, while the total energy flux of jet is larger than that of wind by at most a factor of 10. This result suggests that wind potentially plays a more important role than jet at least for some problems in active galactic nuclei feedback.