# Discovering AGN-driven winds through their infrared emission: II. Mass outflow rate and energetics

## TL;DR

This study analyzes a large sample of AGN-driven outflows using infrared and emission line data to accurately determine their mass and energy, revealing higher densities and lower outflow rates than previously thought.

## Contribution

It introduces a new method to estimate electron density in outflows, leading to revised, lower outflow mass rates and energetics, and highlights the presence of significant neutral atomic gas.

## Key findings

- Electron densities are about 10^4.5 cm^-3, much higher than previous estimates.
- Mass outflow rates are around 10^-2 solar masses per year, lower than earlier estimates.
- Neutral atomic gas mass exceeds ionized gas mass, affecting outflow energetics.

## Abstract

The global influence of AGN-driven outflows remains uncertain, due to a lack of large samples with accurately-determined outflow properties. In the second paper of this series, we determine the mass and energetics of ionized outflows is 234 type II AGN, the largest such sample to date, by combining the infrared emission of the dust in the wind (paper I) with the emission line properties. We provide new general expressions for the properties of the outflowing gas, which depend on the ionization state of the gas. We also present a novel method to estimate the electron density in the outflow, based on optical line ratios and on the known location of the wind. The inferred electron densities, $n_{\mathrm{e}} \sim 10^{4.5}\,\mathrm{(cm^{-3})}$, are two orders of magnitude larger than typically found in most other cases of ionized outflows. We argue that the discrepancy is due to the fact that the commonly-used [SII]-based method underestimates the true density by a large factor. As a result, the inferred mass outflow rates and kinetic coupling efficiencies are $\dot{M}_{\mathrm{out}} \sim 10^{-2}\, \mathrm{(M_{\odot}/yr)}$ and $\epsilon = \dot{E}_{\mathrm{kin}}/L_{\mathrm{bol}} \sim 10^{-5}$ respectively, 1--2 orders of magnitude lower than previous estimates. Our analysis suggests the existence of a significant amount of neutral atomic gas at the back of the outflowing ionized gas clouds, with mass that is a factor of a few larger than the observed ionized gas mass. This has significant implications for the estimated mass and energetics of such flows.