On the wind production from hot accretion flows with different accretion rates

TL;DR

This study uses two-dimensional simulations to explore how wind strength in hot accretion flows varies with accretion rate, revealing strong winds at low rates and weak winds when radiative cooling becomes significant.

Contribution

It provides new insights into the dependence of wind strength on accretion rate and cooling processes in hot accretion flows, with implications for AGN feedback models.

Findings

Wind flux can be about 50% of inflow at low accretion rates.

Wind weakens significantly when radiative cooling forms cold clumps.

Radiative cooling influences wind strength and flow structure.

Abstract

We perform two-dimensional simulations to study how the wind strength changes with accretion rate. We take into account bremsstrahlung, synchrotron radiation and the Comptonization. We find that when the accretion rate is low, radiative cooling is not important, the accretion flow is hot accretion flow. For the hot accretion flow, wind is very strong. The mass flux of wind can be $\sim 50\%$ of the mass inflow rate. When the accretion rate increases to a value at which radiative cooling rate is roughly equal to or slightly larger than viscous heating rate, cold clumps can form around the equatorial plane. In this case, the gas pressure gradient force is small and wind is very weak. Our results may be useful for the sub-grid model of active galactic nuclear feedback study.